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1
Allison, T., C. C. Wood, G. McCarthy, and D. D. Spencer. "Cortical somatosensory evoked potentials. II. Effects of excision of somatosensory or motor cortex in humans and monkeys." Journal of Neurophysiology 66, no. 1 (July 1, 1991): 64–82. http://dx.doi.org/10.1152/jn.1991.66.1.64.
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1. To clarify the generators of human short-latency somatosensory evoked potentials (SEPs) thought to arise in sensorimotor cortex, we studied the effects on SEPs of surgical excision of somatosensory or motor cortex in humans and monkeys. 2. Normal median nerve SEPs (P20-N30, N20-P30, and P25-N35) were recorded from the cortical surface of a patient (G13) undergoing a cortical excision for relief of focal seizures. All SEPs were abolished both acutely and chronically after excision of the hand area of somatosensory cortex. Similarly, excision of the hand area of somatosensory cortex abolished corresponding SEPs (P10-N20, N10-P20, and P12-N25) in monkeys. Excision of the crown of monkey somatosensory cortex abolished P12-N25 while leaving P10-N20 and N10-P20 relatively unaffected. 3. After excision of the hand area of motor cortex, all SEPs were present when recorded from the cortical surface of a patient (W1) undergoing a cortical excision for relief of focal seizures. Similarly, all SEPs were present in monkeys after excision of the hand area of motor cortex. 4. Although all SEPs were present after excision of motor cortex in monkeys, variable changes were observed in SEPs after the excisions. However, these changes were not larger than the changes observed after excision of parietal cortex posterior to somatosensory cortex. We concluded that the changes were not specific to motor cortex excision. 5. These results support two major conclusions. 1) Median nerve SEPs recorded from sensorimotor cortex are produced by generators in two adjacent regions of somatosensory cortex: a tangentially oriented generator in area 3b, which produces P20-N30 (human) and P10-N20 (monkey) [recorded anterior to the central sulcus (CS)] and N20-P30 (human) and N10-P20 (monkey) posterior to the CS; and a radially oriented generator in area 1, which produces P25-N35 (human) and P12-N25 (monkey) recorded from the postcentral gyrus near the CS. 2) Motor cortex makes little or no contribution to these potentials.
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Lawrence, Donald G. "Central Neural Mechanisms of Prehension." Canadian Journal of Physiology and Pharmacology 72, no. 5 (May 1, 1994): 580–82. http://dx.doi.org/10.1139/y94-082.
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The digital dexterity seen in man and macaque monkeys but not present in other primates, such as the squirrel monkey, occurs without anatomical specialization of the hand. The central nervous system apparatus essential to such dexterity resides in the motor cortex and its outflow to lower centres. Areas other than the motor cortex are involved in the initiation and execution of complex sequential movements, including those of the fingers and hand. These include the supplementary motor and premotor areas of the cerebral cortex and the lateral parts of the cortex and the deep nuclei of the cerebellum.Key words: motor cortex, corticomotoneuronal projections, supplementary motor area, premotor area, cerebellum.
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Murray, G. M., L. D. Lin, E. M. Moustafa, and B. J. Sessle. "Effects of reversible inactivation by cooling of the primate face motor cortex on the performance of a trained tongue-protrusion task and a trained biting task." Journal of Neurophysiology 65, no. 3 (March 1, 1991): 511–30. http://dx.doi.org/10.1152/jn.1991.65.3.511.
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1. Intracortical microstimulation (ICMS) and surface stimulation studies of primate face motor cortex have shown an extensive representation within face motor cortex devoted to movements of the tongue and face; only a very small representation for jaw-closing movements has ever been demonstrated. These data suggest that face motor cortex plays a critical role in the generation of tongue and facial movements but is less important in the generation of jaw-closing movements. Our aim was to determine whether disruption of primate face motor cortical function would indeed interfere with the generation of tongue movements but would not interfere with the generation of jaw-closing movements. 2. The face motor cortex was reversibly inactivated with the use of cooling in two monkeys that were trained to perform both a tongue-protrusion task and a biting task. Recording of single neuronal activity in the cortex beneath the thermode confirmed the reversible inactivation of the cortex. Each task involved a series of trials in which the monkey was required to produce a preset force level for a 0.5-s force holding period; the monkey received a fruit-juice reward if it successfully completed a task trial. Cooling of the ICMS-defined face motor cortex was achieved bilaterally or, in one experiment, unilaterally by circulating coolant through thermodes placed either on intact dura overlying face motor cortex in both monkeys or directly on the exposed pia in one of the monkeys;thermode temperature was lowered to 3-5 degrees C during cooling. Electromyographic (EMG) recordings were also made from masseter, genioglossus, and digastric muscles. 3. During bilateral cooling of the thermodes on the dura overlying the face motor cortex, there was a significant reduction in the success rates for the performance of the tongue-protrusion task in comparison with control series of trials (i.e., precool and postcool) in which the thermodes were kept at 37 degrees C. Quantitative analyses of force and EMG activity showed that the principal deficit was an inability of each monkey to exert sufficient force with its tongue for a sufficient length of time onto the tongue-protrusion task transducer; this deficit was paralleled by a reduction in the level of genioglossus and digastric EMG activity. At 4 min after commencement of rewarming, task performance had returned to control, precool levels.(ABSTRACT TRUNCATED AT 400 WORDS)
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Qi, Hui-Xin, Iwona Stepniewska, and Jon H. Kaas. "Reorganization of Primary Motor Cortex in Adult Macaque Monkeys With Long-Standing Amputations." Journal of Neurophysiology 84, no. 4 (October 1, 2000): 2133–47. http://dx.doi.org/10.1152/jn.2000.84.4.2133.
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The organization of primary motor cortex (M1) of adult macaque monkeys was examined years after therapeutic amputation of part of a limb or digits. For each case, a large number of sites in M1 were electrically stimulated with a penetrating microelectrode, and the evoked movements and levels of current needed to evoke the movements were recorded. Results from four monkeys with the loss of a forelimb near or above the elbow show that extensive regions of cortex formerly devoted to the missing hand evoked movements of the stump and the adjoining shoulder. Threshold current levels for stump movements were comparable to those for normal arm movements. Few or no sites in the estimated former territory of the hand evoked face movements. Similar patterns of reorganization were observed in all four cases, which included two monkeys injured as adults, one as a juvenile, and one as an infant. In a single monkey with a hindlimb amputation at the knee as an infant, stimulation of cortex in the region normally devoted to the foot moved the leg stump, again at thresholds in the range for normal movements. Finally, in a monkey that had lost digit 5 and the distal phalanges of digits 2–4 at 2 yr of age, much of the hand portion of M1 was devoted to movements of the digit stumps.
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Widener, Gail L., and Paul D. Cheney. "Effects on Muscle Activity From Microstimuli Applied to Somatosensory and Motor Cortex During Voluntary Movement in the Monkey." Journal of Neurophysiology 77, no. 5 (May 1, 1997): 2446–65. http://dx.doi.org/10.1152/jn.1997.77.5.2446.
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Widener, Gail L. and Paul D. Cheney. Effects on muscle activity from microstimuli applied to somatosensory and motor cortex during voluntary movement in the monkey. J. Neurophysiol. 77: 2446–2465, 1997. It is well known that electrical stimulation of primary somatosensory cortex (SI) evokes movements that resemble those evoked from primary motor cortex. These findings have led to the concept that SI may possess motor capabilities paralleling those of motor cortex and speculation that SI could function as a robust relay mediating motor responses from central and peripheral inputs. The purpose of this study was to rigorously examine the motor output capabilities of SI areas with the use of the techniques of spike- and stimulus-triggered averaging of electromyographic (EMG) activity in awake monkeys. Unit recordings were obtained from primary motor cortex and SI areas 3a, 3b, 1, and 2 in three rhesus monkeys. Spike-triggered averaging was used to assess the output linkage between individual cells and motoneurons of the recorded muscles. Cells in motor cortex producing postspike facilitation (PSpF) in spike-triggered averages of rectified EMG activity were designated corticomotoneuronal (CM) cells. Motor output efficacy was also assessed by applying stimuli through the microelectrode and computing stimulus-triggered averages of rectified EMG activity. One hundred seventy-one sites in motor cortex and 68 sites in SI were characterized functionally and tested for motor output effects on muscle activity. The incidence, character, and magnitude of motor output effects from SI areas were in sharp contrast to effects from CM cell sites in primary motor cortex. Of 68 SI cells tested with spike-triggered averaging, only one area 3a cell produced significant PSpF in spike-triggered averages of EMG activity. In comparison, 20 of 171 (12%) motor cortex cells tested produced significant postspike effects. Single-pulse intracortical microstimulation produced effects at all CM cell sites in motor cortex but at only 14% of SI sites. The large fraction of SI effects that was inhibitory represented yet another marked difference between CM cell sites in motor cortex and SI sites (25% vs 93%). The fact that motor output effects from SI were frequently absent or very weak and predominantly inhibitory emphasizes the differing motor capabilities of SI compared with primary motor cortex.
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Moore, T., H. R. Rodman, A. B. Repp, C. G. Gross, and R. S. Mezrich. "Greater residual vision in monkeys after striate cortex damage in infancy." Journal of Neurophysiology 76, no. 6 (December 1, 1996): 3928–33. http://dx.doi.org/10.1152/jn.1996.76.6.3928.
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1. Monkeys with large unilateral surgical ablations of striate cortex, sustained either in adulthood or at 5–6 wk of age, were trained on an oculomotor detection and localization task and tested with visual stimuli in the hemifields ipsilateral and contralateral to the lesion 2–5 yr after surgery. 2. Monkeys with lesions sustained in adulthood were largely unable to detect stimuli in the hemifield contralateral to the lesion, with only one monkey showing recovery toward the end of testing. Monkeys with lesions of striate cortex made in infancy, however, each showed residual detection capacity at the beginning of testing and improved to near normal by the end of testing. 3. Each of the monkeys showing a residual ability to detect within the contralateral hemifield was also able to localize visual targets with eye movements. 4. These findings demonstrate that the vision surviving striate cortex damage in primates is more robust after early damage as has been shown to be the case for primary somatosensory, motor, and association cortex.
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Simon, Stéphane R., Martine Meunier, Loÿs Piettre, Anna M. Berardi, Christoph M. Segebarth, and Driss Boussaoud. "Spatial Attention and Memory Versus Motor Preparation: Premotor Cortex Involvement as Revealed by fMRI." Journal of Neurophysiology 88, no. 4 (October 1, 2002): 2047–57. http://dx.doi.org/10.1152/jn.2002.88.4.2047.
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Recent studies in both monkeys and humans indicate that the dorsal premotor cortex participates in spatial attention and working memory, in addition to its well known role in movement planning and execution. One important question is whether these functions overlap or are segregated within this frontal area. Single-cell recordings in monkeys suggest a relative specialization of the rostral portion of dorsal premotor cortex for attention and/or memory and of the caudal region for motor preparation. To test whether this possibility also holds true in humans, we used functional magnetic resonance imaging (fMRI) to compare, in the same set of subjects, brain activation related to strong spatial attention and memory demands to that elicited by long motor preparatory periods. The behavioral protocol was based on a task that had proved effective for dissociating neuronal properties related to these two functions in the monkey brain. The principle of the monkey task was that a first cue guided the focus of spatial attention and memory, whereas a second one instructed an arm movement. Based on this principle, two tasks were developed. One maximized spatial attention and memory demands by presenting long series of stimuli (4, 8, or 12) before the motor instructional cue, whereas the other extended the motor preparation phase by imposing long and variable delays (1–5.5 s) between the onset of the instructional cue and movement execution. The two tasks and their respective control conditions were arranged in two blocked-design sequences. The results indicate that the brain networks underlying the two functional domains overlap in the caudate nucleus and presupplementary motor area, and possibly in lateral prefrontal cortex as well, but involve different dorsal premotor fields. Motor preparation primarily recruited a dorsal premotor area located caudally, within the precentral gyrus (together with the supplementary motor area), whereas spatial attention and memory preferentially activated a more rostral site, in and anterior to the precentral sulcus (in addition to the posterior parietal cortex). These findings strengthen the idea that the primate dorsal premotor cortex contributes to both motor and nonmotor processes. Moreover, they corroborate emerging evidence from monkey physiology suggesting a relative functional segregation within this cortex, with attention to short-term storage of visuospatial information engaging a more rostral region than motor preparation.
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Bracewell, R. M., P. Mazzoni, S. Barash, and R. A. Andersen. "Motor intention activity in the macaque's lateral intraparietal area. II. Changes of motor plan." Journal of Neurophysiology 76, no. 3 (September 1, 1996): 1457–64. http://dx.doi.org/10.1152/jn.1996.76.3.1457.
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1. In the companion paper we reported that the predominant signal of the population of neurons in the lateral intraparietal area (area LIP) of the monkey's posterior parietal cortex (PPC) encode the next intended saccadic eye movement during the delay period of a memory-saccade task. This result predicts that, should be monkey change his intention of what the next saccade will be, LIP activity should change accordingly to reflect the new plan. We tested this prediction by training monkeys to change their saccadic plan on command and recording the activity of LIP neurons across plan changes. 2. We trained rhesus monkeys (Macaca mulatta) to maintain fixation on a light spot as long as this spot remained on. During this period we briefly presented one, two, or three peripheral visual stimuli in sequence, each followed by a delay (memory period, M). After the final delay the fixation spot was extinguished, and the monkey had to quickly make a saccade to the location of the last target to have appeared. The monkey could not predict which stimuli, nor how many, would appear on each trial. He thus had to plan a saccade to each stimulus as it appeared and change his saccade plan whenever a stimulus appeared at a different location. 3. We recorded the M period activity of 81 area LIP neurons (from 3 hemispheres of 2 monkeys) in this task. We predicted that, if a neuron's activity reflected the monkey's planned saccade, its activity should be high while the monkey planned a saccade in the neuron's motor field (MF), and low while the planned saccade was in the opposite direction. The activity of most of the neurons in our sample changed in accordance with our hypothesis as the monkey's planned saccade changed. 4. In one condition the monkey was instructed by visual stimuli to change his plan from a saccade in the neuron's preferred direction to a saccade planned in the opposite direction. In this condition activity decreased significantly (P < 0.05) in 65 (80%) of 81 neurons tested. These neurons' activity changed to reflect the new saccade plan even though the cue for this change was not presented in their RF. 5. As a control we randomly interleaved, among trials requiring a plan change, trials in which the monkey had to formulate two consecutive plans to make a saccade in the neuron's preferred direction. The activity remained unchanged (P < 0.05) in 22 of 31 neurons tested (79%), indicating that the neurons continued to encode the same saccade plan. 6. In a variant of the task, the cue to the location of the required saccade was either a light spot or a noise burst from a loudspeaker. Of 22 neurons tested in this task, 16 (73%) showed activity changes consistent with plan changes cued by visual or auditory stimuli. 7. Alterations in the monkey's intentions, even in the absence of overt behavior, are manifested in altered LIP activity. These activity changes could be induced whether visual or auditory cues were used to indicate the required plan changes. Most LIP neurons thus do not encode only the locations of visual stimuli, but also the intention to direct gaze to specific locations, independently of whether a gaze shift actually occurs.
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Kurata, Kiyoshi, and Eiji Hoshi. "Reacquisition Deficits in Prism Adaptation After Muscimol Microinjection Into the Ventral Premotor Cortex of Monkeys." Journal of Neurophysiology 81, no. 4 (April 1, 1999): 1927–38. http://dx.doi.org/10.1152/jn.1999.81.4.1927.
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Reacquisition deficits in prism adaptation after muscimol microinjection into the ventral premotor cortex of monkeys. A small amount of muscimol (1 μl; concentration, 5 μg/μl) was injected into the ventral and dorsal premotor cortex areas (PMv and PMd, respectively) of monkeys, which then were required to perform a visually guided reaching task. For the task, the monkeys were required to reach for a target soon after it was presented on a screen. While performing the task, the monkeys’ eyes were covered with left 10°, right 10°, or no wedge prisms, for a block of 50–100 trials. Without the prisms, the monkeys reached the targets accurately. When the prisms were placed, the monkeys initially misreached the targets because the prisms displaced the visual field. Before the muscimol injection, the monkeys adapted to the prisms in 10–20 trials, judging from the horizontal distance between the target location and the point where the monkey touched the screen. After muscimol injection into the PMv, the monkeys lost the ability to readapt and touched the screen closer to the location of the targets as seen through the prisms. This deficit was observed at selective target locations, only when the targets were shifted contralaterally to the injected hemisphere. When muscimol was injected into the PMd, no such deficits were observed. There were no changes in the reaction and movement times induced by muscimol injections in either area. The results suggest that the PMv plays an important role in motor learning, specifically in recalibrating visual and motor coordinates.
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Pavlides, C., E. Miyashita, and H. Asanuma. "Projection from the sensory to the motor cortex is important in learning motor skills in the monkey." Journal of Neurophysiology 70, no. 2 (August 1, 1993): 733–41. http://dx.doi.org/10.1152/jn.1993.70.2.733.
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1. The projection from the somatosensory cortex to the primary motor cortex has been proposed to play an important role in learning novel motor skills. This hypothesis was examined by studying the effects of lesions to the sensory cortex on learning of new motor skills. 2. We used two experimental paradigms to reveal the effects of lesions on learning of new motor skills. One task was to catch a food pellet falling at various velocities. The other task was to catch a food pellet from a rotating level. Both tasks required acquisition of novel motor skills. 3. The training was started after a lesion of the hand area in the somatosensory cortex of one hemisphere. In both tasks, monkeys had severe difficulty in learning the new skills with the hand contralateral to the ablated somatosensory cortex, compared with the hand contralateral to the intact hemisphere. 4. After acquisition of the motor skill in the hand contralateral to intact hemisphere, lesion of the somatosensory cortex hand area did not abolish the learned motor skill. 5. In control experiments, monkeys were trained to pick up a food pellet from a rotating board. This task did not necessitate acquisition of new motor skills, but could be performed by utilizing existing motor skills. Lesion in the somatosensory cortex before or after the training did not affect the execution of this task by either hand. 6. It is concluded that the corticocortical projection from the somatosensory to the motor cortex plays an important role in learning new motor skills, but not in the execution of existing motor skills.
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Cléry, Justine, Céline Amiez, Olivier Guipponi, Claire Wardak, Emmanuel Procyk, and Suliann Ben Hamed. "Reward activations and face fields in monkey cingulate motor areas." Journal of Neurophysiology 119, no. 3 (March 1, 2018): 1037–44. http://dx.doi.org/10.1152/jn.00749.2017.
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Several premotor areas have been identified within primate cingulate cortex; however their function is yet to be uncovered. Recent brain imaging work in humans revealed a topographic anatomofunctional overlap between feedback processing during exploratory behaviors and the corresponding body fields in the rostral cingulate motor area (RCZa), suggesting an embodied representation of feedback. In particular, a face field in RCZa processes juice feedback. Here we tested an extension of the embodied principle in which unexpected or relevant information obtained through the eye or the face would be processed by face fields in cingulate motor areas, and whether this applied to monkey cingulate cortex. We show that activations for juice reward, eye movement, eye blink, and tactile stimulation on the face overlap over two subfields within the cingulate sulcus likely corresponding to the rostral and caudal cingulate motor areas. This suggests that in monkeys as is the case in humans, behaviorally relevant information is processed through multiple cingulate body/effector maps. NEW & NOTEWORTHY What is the role of cingulate motor areas? In this study we observed in monkeys that, as in humans, neural responses to face-related events, juice reward, eye movement, eye blink, and tactile stimulations, clustered redundantly in two separate cingulate subfields. This suggests that behaviorally relevant information is processed by multiple cingulate effector maps. Importantly, this overlap supports the principle that the cingulate cortex processes feedback based on where it is experienced on the body.
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Elsworth, John D., Csaba Leranth, D. Eugene Redmond, and Robert H. Roth. "Loss of asymmetric spine synapses in prefrontal cortex of motor-asymptomatic, dopamine-depleted, cognitively impaired MPTP-treated monkeys." International Journal of Neuropsychopharmacology 16, no. 4 (May 1, 2013): 905–12. http://dx.doi.org/10.1017/s1461145712000892.
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Abstract Parkinson's disease is usually characterized as a movement disorder; however, cognitive abilities that are dependent on the prefrontal cortex decline at an early stage of the disease in most patients. The changes that underlie cognitive deficits in Parkinson's disease are not well understood. We hypothesize that reduced dopamine signalling in the prefrontal cortex in Parkinson's disease is a harbinger of detrimental synaptic changes in pyramidal neurons in the prefrontal cortex, whose function is necessary for normal cognition. Our previous data showed that monkeys exposed to the neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), but not exhibiting overt motor deficits (motor-asymptomatic), displayed cognitive deficits in prefrontal cortex-dependent tasks. The present results demonstrate that motor-asymptomatic MPTP-treated monkeys have a reduced dopamine concentration and a substantially lower number (50%) of asymmetric (excitatory) spine synapses in layer II/III, but not layer V, of the dorsolateral prefrontal cortex, compared to controls. In contrast, neither dopamine concentration nor asymmetric synapse number was altered in the entorhinal cortex of MPTP-treated monkeys. Together, these findings suggest that the number of asymmetric spine synapses on dendrites in the prefrontal cortex is dopamine-dependent and that the loss of synapses may be a morphological substrate of the cognitive deficits induced by a reduction in dopamine neurotransmission in this region.
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Roesch, Matthew R., and Carl R. Olson. "Impact of Expected Reward on Neuronal Activity in Prefrontal Cortex, Frontal and Supplementary Eye Fields and Premotor Cortex." Journal of Neurophysiology 90, no. 3 (September 2003): 1766–89. http://dx.doi.org/10.1152/jn.00019.2003.
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In several regions of the macaque brain, neurons fire during delayed response tasks at a rate determined by the value of the reward expected at the end of the trial. The activity of these neurons might be related either to the internal representation of the appetitive value of the expected reward or to motivation-dependent variations in the monkey's level of motor preparation or motor output. According to the first interpretation, reward-related activity should be most prominent in areas affiliated with the limbic system. According to the second interpretation, it should be most prominent in areas affiliated with the motor system. To distinguish between these alternatives, we carried out single-neuron recording while monkeys performed a memory-guided saccade task in which a visual cue presented early in each trial indicated whether the reward would be large or small. Neuronal activity accompanying task performance was monitored in the dorsolateral prefrontal cortex (PFC), the frontal eye field (FEF), a transitional zone caudal to the frontal eye field (FEF/PM), premotor cortex (PM), the supplementary eye field (SEF), and the rostral part of the supplementary motor area (SMAr). The tendency for neuronal activity to increase after cues that predicted a large reward became progressively stronger in progressively more posterior areas both in the lateral sector of the frontal lobe (PFC < FEF < FEF/PM < PM) and in the medial sector (SEF < SMAr). The very strong reward-related activity of premotor neurons was presumably attributable to the monkey's motivation-dependent level of motor preparation or motor output. This finding points to the need to determine whether reward-related activity in other nonlimbic brain areas, including dorsolateral prefrontal cortex and the dorsal striatum, genuinely represents the value of the expected reward or, alternatively, is related to motivational modulation of motor signals.
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Kurata, Kiyoshi, and Eiji Hoshi. "Movement-Related Neuronal Activity Reflecting the Transformation of Coordinates in the Ventral Premotor Cortex of Monkeys." Journal of Neurophysiology 88, no. 6 (December 1, 2002): 3118–32. http://dx.doi.org/10.1152/jn.00070.2002.
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We examined how the transformation of coordinates from visual to motor space is reflected by neuronal activity in the ventral premotor cortex (PMv) of monkeys. Three monkeys were trained to reach with their right hand for a target that appeared on a screen. While performing the task, the monkeys wore prisms that shifted the image of the target 10°, left or right, or wore no prisms, for a block of 200 trials. The nine targets were located in the same positions in visual space regardless of whether the prisms were present. Wearing the prisms required the monkeys to initiate a movement in a direction that was different from the apparent target location. Thus using the prisms, we could dissociate visual space from motor space. While the monkey performed the behavioral task, we recorded neuronal activity in the left PMv and primary motor cortex (MI), and various kinds of task-related neuronal activity were found in the motor areas. These included neurons that changed their activity during a reaction time (RT) period (the period between target presentation and movement onset), which were called “movement-related neurons” and selected for analysis. In these neurons, activity during a movement time (MT) period was also compared. Using general linear models for our statistical analysis, the neurons were then classified into four types: those whose activity was consistently dependent on location of targets in the visual coordinates regardless of whether the prisms were present or absent (V type); those that were consistently dependent on target location in the motor coordinates only; those that had different activity for both of the motor and visual coordinates; and those that had nondifferential activity for the two types of coordinates. The proportion of the four types of the neurons differed significantly between the PMv and MI. Most remarkably, neurons with V-type activity were almost exclusively recorded in the PMv and were almost exclusively found during the RT period. Such activity was never observed in an electromyogram of the working forelimb. Based on these observations, we postulate that the V and other types may represent the various intermediate stages of the transformation of coordinates and that the PMv plays a crucial role in transforming coordinates from visual to motor space.
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NAKAO, Kazuko, Ryuichi MATSUZAKI, Yusaku AMAYA, Shin-ichi KYUHOU, and Hisae GEMBA. "Motor Functions of the Posterior Parietal Cortex in Monkeys." Journal of Kansai Medical University 58, no. 2-4 (2006): 153–62. http://dx.doi.org/10.5361/jkmu1956.58.2-4_153.
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Dum, Richard P., David J. Levinthal, and Peter L. Strick. "The mind–body problem: Circuits that link the cerebral cortex to the adrenal medulla." Proceedings of the National Academy of Sciences 116, no. 52 (December 23, 2019): 26321–28. http://dx.doi.org/10.1073/pnas.1902297116.
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Which regions of the cerebral cortex are the origin of descending commands that influence internal organs? We used transneuronal transport of rabies virus in monkeys and rats to identify regions of cerebral cortex that have multisynaptic connections with a major sympathetic effector, the adrenal medulla. In rats, we also examined multisynaptic connections with the kidney. In monkeys, the cortical influence over the adrenal medulla originates from 3 distinct networks that are involved in movement, cognition, and affect. Each of these networks has a human equivalent. The largest influence originates from a motor network that includes all 7 motor areas in the frontal lobe. These motor areas are involved in all aspects of skeletomotor control, from response selection to motor preparation and movement execution. The motor areas provide a link between body movement and the modulation of stress. The cognitive and affective networks are located in regions of cingulate cortex. They provide a link between how we think and feel and the function of the adrenal medulla. Together, the 3 networks can mediate the effects of stress and depression on organ function and provide a concrete neural substrate for some psychosomatic illnesses. In rats, cortical influences over the adrenal medulla and the kidney originate mainly from 2 motor areas and adjacent somatosensory cortex. The cognitive and affective networks, present in monkeys, are largely absent in rats. Thus, nonhuman primate research is essential to understand the neural substrate that links cognition and affect to the function of internal organs.
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Murata, Yumi, Noriyuki Higo, Takao Oishi, Akiko Yamashita, Keiji Matsuda, Motoharu Hayashi, and Shigeru Yamane. "Effects of Motor Training on the Recovery of Manual Dexterity After Primary Motor Cortex Lesion in Macaque Monkeys." Journal of Neurophysiology 99, no. 2 (February 2008): 773–86. http://dx.doi.org/10.1152/jn.01001.2007.
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To investigate the effects of postlesion training on motor recovery, we compared the motor recovery of macaque monkeys that had received intensive motor training with those that received no training after a lesion of the primary motor cortex (M1). An ibotenic acid lesion in the M1 digit area resulted in impairment of hand function, with complete loss of digit movement. In the monkeys that had undergone intensive daily training (1 h/day, 5 days/wk) after the lesion, behavioral indexes used to evaluate manual dexterity recovered to the same level as in the prelesion period after 1 or 2 mo of postlesion training period. Relatively independent digit movements, including precision grip (prehension of a small object with finger-to-thumb opposition), were restored in the trained monkeys. Although the behavioral indexes of manual dexterity recovered to some extent in the monkeys without the postlesion training, they remained lower than those in the prelesion period until several months after M1 lesion. The untrained monkeys frequently used alternate grip strategies to grasp a small object with the affected hand, holding food pellets between the tip of the index finger and the dorsum of the thumb. These results suggest that the recovery after M1 lesion includes both use-dependent and use-independent processes and that the recovery of precision grip can be promoted by intensive use of the affected hand in postlesion training.
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Fraser, George W., and Andrew B. Schwartz. "Recording from the same neurons chronically in motor cortex." Journal of Neurophysiology 107, no. 7 (April 1, 2012): 1970–78. http://dx.doi.org/10.1152/jn.01012.2010.
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Two rhesus monkeys were implanted with silicon arrays of 96 microelectrodes. Neural activity was recorded periodically over a period of weeks to months. We have developed a method to determine whether single units in two separate recording sessions represent the same neuron. Pairwise cross-correlograms, the autocorrelogram, waveform shape, and mean firing rate were used together as identifying features of a neuron. When two units recorded on separate days were compared using these features, their similarity scores tended to be either high, indicating two recordings from the same neuron, or low, indicating different neurons. Although these metrics are individually weak, together they produce a strong classifier. Some neurons were recorded for >100 days. These monkeys performed a center-out reaching task, and we found that the firing properties of chronically recorded neurons were stable over time.
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Kurata, Kiyoshi. "Laterality of Movement-Related Activity Reflects Transformation of Coordinates in Ventral Premotor Cortex and Primary Motor Cortex of Monkeys." Journal of Neurophysiology 98, no. 4 (October 2007): 2008–21. http://dx.doi.org/10.1152/jn.00149.2007.
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The ventral premotor cortex (PMv) and the primary motor cortex (MI) of monkeys participate in various sensorimotor integrations, such as the transformation of coordinates from visual to motor space, because the areas contain movement-related neuronal activity reflecting either visual or motor space. In addition to relationship to visual and motor space, laterality of the activity could indicate stages in the visuomotor transformation. Thus we examined laterality and relationship to visual and motor space of movement-related neuronal activity in the PMv and MI of monkeys performing a fast-reaching task with the left or right arm, toward targets with visual and motor coordinates that had been dissociated by shift prisms. We determined laterality of each activity quantitatively and classified it into four types: activity that consistently depended on target locations in either head-centered visual coordinates (V-type) or motor coordinates (M-type) and those that had either differential or nondifferential activity for both coordinates (B- and N-types). A majority of M-type neurons in the areas had preferences for reaching movements with the arm contralateral to the hemisphere where neuronal activity was recorded. In contrast, most of the V-type neurons were recorded in the PMv and exhibited less laterality than the M-type. The B- and N-types were recorded in the PMv and MI and exhibited intermediate properties between the V- and M-types when laterality and correlations to visual and motor space of them were jointly examined. These results suggest that the cortical motor areas contribute to the transformation of coordinates to generate final motor commands.
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Messinger, Adam, Rossella Cirillo, Steven P. Wise, and Aldo Genovesio. "Separable neuronal contributions to covertly attended locations and movement goals in macaque frontal cortex." Science Advances 7, no. 14 (March 2021): eabe0716. http://dx.doi.org/10.1126/sciadv.abe0716.
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We investigated the spatial representation of covert attention and movement planning in monkeys performing a task that used symbolic cues to decouple the locus of covert attention from the motor target. In the three frontal areas studied, most spatially tuned neurons reflected either where attention was allocated or the planned saccade. Neurons modulated by both covert attention and the motor plan were in the minority. Such dual-purpose neurons were especially rare in premotor and prefrontal cortex but were more common just rostral to the arcuate sulcus. The existence of neurons that indicate where the monkey was attending but not its movement goal runs counter to the idea that the control of spatial attention is entirely reliant on the neuronal circuits underlying motor planning. Rather, the presence of separate neuronal populations for each cognitive process suggests that endogenous attention is under flexible control and can be dissociated from motor intention.
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Milliken, Garrett W., Erik J. Plautz, and Randolph J. Nudo. "Distal forelimb representations in primary motor cortex are redistributed after forelimb restriction: a longitudinal study in adult squirrel monkeys." Journal of Neurophysiology 109, no. 5 (March 1, 2013): 1268–82. http://dx.doi.org/10.1152/jn.00044.2012.
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Primary motor cortex (M1) movement representations reflect acquired motor skills. Representations of muscles and joints used in a skilled task expand. However, it is unknown whether motor restriction in healthy individuals results in complementary reductions in M1 representations. With the use of intracortical microstimulation techniques in squirrel monkeys, detailed maps of movement representations in M1 were derived before and up to 35 wk after restriction of the preferred distal forelimb (DFL) by use of a soft cast. Although total DFL area and movement threshold remained constant, casting resulted in a redistribution of digit and wrist/forearm representations. Digit representations progressively decreased, whereas wrist/forearm representations progressively increased in areal extent. In three of four monkeys, hand preference returned to normal by the end of the postcast recovery period, and postrecovery maps demonstrated reversal of restriction-induced changes. However, in one monkey, a chronic motor impairment occurred in the casted limb. Rehabilitation via a forced-use paradigm resulted in recovery in use and skill of the impaired limb, as well as restoration of normal motor maps. These results demonstrate that plasticity in motor representations can be induced by training or restricting movements of the limb. Physiological changes induced by restriction appear to be reversible, even in the case of adverse motor outcomes. The respective contributions of both disuse and lost motor skills are discussed. These results have relevance for clinical conditions requiring forelimb casting as well as interpreting the differential effects of injury and disuse that are necessarily intertwined after cortical injury, as occurs in stroke.
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Matsuzaka, Y., and J. Tanji. "Changing directions of forthcoming arm movements: neuronal activity in the presupplementary and supplementary motor area of monkey cerebral cortex." Journal of Neurophysiology 76, no. 4 (October 1, 1996): 2327–42. http://dx.doi.org/10.1152/jn.1996.76.4.2327.
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1. To understand roles played by two cortical motor areas, the presupplementary motor area (pre-SMA) and supplementary motor area (SMA), in changing planned movements voluntarily, cellular activity was examined in two monkeys (Macaca fuscata) trained to perform an arm-reaching task in which they were asked to press one of two target buttons (right or left) in three different task modes. 2. In the first mode (visual), monkeys were visually instructed to result and press either a right or left key in response to a forth coming trigger signal. In the second mode (stay), monkeys were required to wait for the trigger signal and press the same target key as pressed in preceding trials. In the third mode (shift), a 50 Hz auditory cue instructed the monkey to shift the target of the future reach from the previous target to the previous nontarget. 3. While the monkeys were performing this task, we recorded 399 task-related cellular activities from the SMA and the pre-SMA. Among them, we found a group of neurons that exhibited activity changes related specifically to shift trials (shift-related cells). The following properties characterized these 112 neurons. First, they exhibited activity changes after the onset of the 50-Hz auditory cue and before the movement execution when the monkeys were required to change the direction of forthcoming movement. Second, they were not active when the monkeys pressed the same key without changing the direction of the movements. Third, they were not active when the monkeys received the 50-Hz auditory cue but failed to change the direction of the movements by mistake. These observations indicate that the activity of shift-related cells is related to the redirection of the forthcoming movements, but not to the auditory instruction itself or to the location of the target key or the direction of the forthcoming movements. 4. Although infrequently, monkeys made errors in the stay trials and changed directions of the reach voluntarily. In that case, a considerably high proportion of shift-related neurons (12 of 19) exhibited significant activity changes long before initiation of the reach movement. These long-lasting activities were not observed during the preparatory period in correct stay trials, but resembled the shift-related activity observed when the target shift was made toward the same direction. Thus these activity changes were considered to be also related to the process of changing the intended movements voluntarily. 5. We found another population of neurons that showed activity modulation when the target shift was induced by the visual instruction in visual trials (visually guided shift-related neurons). These neurons were active when the light-emitting diode (LED) guided the forthcoming reach to the previous nontarget but not to the previous target. Therefore their activity was not a simple visual response to the LED per se. A majority of them also showed shift-related activity in shift trials (19 of 22 in monkey 2). 6. Neurons exhibiting the shift-related activity were distributed differentially among the two areas. In the pre-SMA, 31% of the neurons recorded showed the shift-related activity, whereas in the SMA, only 7% showed such an activity. These results suggest that pre-SMA and SMA play differential roles in updating the motor plans in accordance with current requirements.
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Hu, Dingyin, Shirong Wang, Bo Li, Honghao Liu, and Jiping He. "Spinal Cord Injury-Induced Changes in Encoding and Decoding of Bipedal Walking by Motor Cortical Ensembles." Brain Sciences 11, no. 9 (September 10, 2021): 1193. http://dx.doi.org/10.3390/brainsci11091193.
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Recent studies have shown that motor recovery following spinal cord injury (SCI) is task-specific. However, most consequential conclusions about locomotor functional recovery from SCI have been derived from quadrupedal locomotion paradigms. In this study, two monkeys were trained to perform a bipedal walking task, mimicking human walking, before and after T8 spinal cord hemisection. Importantly, there is no pharmacological therapy with nerve growth factor for monkeys after SCI; thus, in this study, the changes that occurred in the brain were spontaneous. The impairment of locomotion on the ipsilateral side was more severe than that on the contralateral side. We used information theory to analyze single-cell activity from the left primary motor cortex (M1), and results show that neuronal populations in the unilateral primary motor cortex gradually conveyed more information about the bilateral hindlimb muscle activities during the training of bipedal walking after SCI. We further demonstrated that, after SCI, progressively expanded information from the neuronal population reconstructed more accurate control of muscle activity. These results suggest that, after SCI, the unilateral primary motor cortex could gradually regain control of bilateral coordination and motor recovery and in turn enhance the performance of brain–machine interfaces.
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Friel, Kathleen M., Scott Barbay, Shawn B. Frost, Erik J. Plautz, Douglas M. Hutchinson, Ann M. Stowe, Numa Dancause, Elena V. Zoubina, Barbara M. Quaney, and Randolph J. Nudo. "Dissociation of Sensorimotor Deficits After Rostral Versus Caudal Lesions in the Primary Motor Cortex Hand Representation." Journal of Neurophysiology 94, no. 2 (August 2005): 1312–24. http://dx.doi.org/10.1152/jn.01251.2004.
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Primary motor cortex (M1) has traditionally been considered a motor structure. Although neurophysiologic studies have demonstrated that M1 is also influenced by somatosensory inputs (cutaneous and proprioceptive), the behavioral significance of these inputs has yet to be fully defined in primates. The present study describes differential sensory-related deficits after small ischemic lesions in either the rostral or caudal subregion of the M1 hand area in a nonhuman primate. Squirrel monkeys retrieved food pellets out of different sized wells drilled into a Plexiglas board. Before the lesion, monkeys retrieved pellets by directing the hand to the well, inserting fingers directly into it, and extracting the pellet. After a lesion to the rostral portion of M1, monkeys frequently failed to direct the hand accurately to the well. Instead, fingers contacted the surface of the board outside the well before entering the well. These aiming errors are consistent with both the large amount of proximal motor outputs and the predominant proprioceptive inputs of rostral M1. Overall, these aiming errors are suggestive of dysfunctional processing of proprioceptive information or the failure to integrate proprioceptive information with motor commands. In contrast, after a lesion to the caudal portion of M1, monkeys frequently examined their palm visually for the presence of the pellet after an attempted retrieval. These errors are consistent with both the large amount of distal motor outputs and the predominant cutaneous inputs of caudal M1. Thus these errors are suggestive of a deficit in processing of cutaneous information or the failure to integrate cutaneous information with motor commands. Rostral and caudal M1 lesions result in different deficits in sensory-dependent motor control that appear to correlate with broad segregation of motor outputs and previously described sensory inputs of M1.
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Archakov, Denis, Iain DeWitt, Paweł Kuśmierek, Michael Ortiz-Rios, Daniel Cameron, Ding Cui, Elyse L. Morin, et al. "Auditory representation of learned sound sequences in motor regions of the macaque brain." Proceedings of the National Academy of Sciences 117, no. 26 (June 15, 2020): 15242–52. http://dx.doi.org/10.1073/pnas.1915610117.
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Human speech production requires the ability to couple motor actions with their auditory consequences. Nonhuman primates might not have speech because they lack this ability. To address this question, we trained macaques to perform an auditory–motor task producing sound sequences via hand presses on a newly designed device (“monkey piano”). Catch trials were interspersed to ascertain the monkeys were listening to the sounds they produced. Functional MRI was then used to map brain activity while the animals listened attentively to the sound sequences they had learned to produce and to two control sequences, which were either completely unfamiliar or familiar through passive exposure only. All sounds activated auditory midbrain and cortex, but listening to the sequences that were learned by self-production additionally activated the putamen and the hand and arm regions of motor cortex. These results indicate that, in principle, monkeys are capable of forming internal models linking sound perception and production in motor regions of the brain, so this ability is not special to speech in humans. However, the coupling of sounds and actions in nonhuman primates (and the availability of an internal model supporting it) seems not to extend to the upper vocal tract, that is, the supralaryngeal articulators, which are key for the production of speech sounds in humans. The origin of speech may have required the evolution of a “command apparatus” similar to the control of the hand, which was crucial for the evolution of tool use.
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Courtemanche, Richard, Jean-Pierre Pellerin, and Yves Lamarre. "Local Field Potential Oscillations in Primate Cerebellar Cortex: Modulation During Active and Passive Expectancy." Journal of Neurophysiology 88, no. 2 (August 1, 2002): 771–82. http://dx.doi.org/10.1152/jn.2002.88.2.771.
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Cerebellar local field potential (LFP) oscillations were recorded in the paramedian lobule of one hemisphere, while monkeys were in two behavioral conditions: actively performing an elbow flexion-extension or a lever-press task in response to an auditory or visual stimulus to get reward (active condition), or waiting quietly for the reward to come in the same time window after the appearance of the stimulus (passive condition). The oscillations in the paramedian lobule were first characterized in four monkeys, and they showed an idiosyncratic frequency for each monkey, between 13 and 25 Hz. The granule cell layer multi-unit activity was phase-locked with the negative phase of the LFP oscillations, while Purkinje cell simple spikes were also sometimes phase-locked with the LFP. Three monkeys were trained to perform the motor tasks: the LFP oscillations were modulated, in the active condition, in a systematic manner in relation to the lever-press or elbow flexion-extension tasks. During periods when the monkey was waiting to initiate movement, LFP oscillations appeared and then stopped with movement initiation. This modulation was valid for the task being executed with either hand. Surprisingly, the LFP oscillations were also systematically modulated during the passive condition; as the monkey was waiting for the usual time to get a reward passively, oscillations appeared stronger and were stopped by the end of the usual delay, whether the monkey was rewarded or not. This type of modulation was not affected by the length of the stimulus, as long as the reward window was known to the monkey. If the monkey had not been previously trained to the active condition, the modulation appeared in the passive condition. These results show that cerebellar LFP oscillations in the paramedian lobule are reliably present when the monkey is involved in a waiting period, whether this period ends with an active or passive event. This study provides electrophysiological evidence for a specific pattern of activity in the cerebellum for the expectancy of events that are known to be bound to happen, either externally, or from voluntary action.
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Dudkin, K. N., I. V. Chueva, F. N. Makarov, and I. V. Orlov. "Visual Discrimination Learning in Monkeys with Bilateral Parietal Cortex Lesions." Perception 26, no. 1_suppl (August 1997): 131. http://dx.doi.org/10.1068/v970110.
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The characteristics of visual discrimination learning were tested on rhesus monkeys during elaboration of an instrumental reflex after bilateral extirpation of the parietal cortex area 7. The animals were trained to discriminate stimuli with different visual attributes (shape, colour, orientation, size, spatial relationships). Their decisions and motor reaction times were recorded. Bilateral extirpation of area 7 did not influence learning characteristics for shape and colour discrimination. The duration of the learning process and the motor reaction time were shortest with these visual attributes. When monkeys were required to discriminate geometrical figures of different orientations and size, these learning characteristics slightly increased. However, learning to discriminate spatial relationships was dramatically impaired. As a result, the duration of the learning process and motor reaction time significantly increased and the level of correct decisions after training significantly decreased. Visual stimuli associated with identical learning characteristics formed distinct groups in a cluster analysis. These results support the suggestion that area 7 is a structural and functional component of mechanisms involved in evaluation of spatial relationships. The impairment of the learning to discriminate spatial relationships can be explained by a change of learning strategy upon disturbance of this mechanism, associated with visual-vestibular interactions and synchronisation processes which bind distributed neurons across different cortical areas into synchronised assemblies.
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Nashef, Abdulraheem, Rea Mitelman, Ran Harel, Mati Joshua, and Yifat Prut. "Area-specific thalamocortical synchronization underlies the transition from motor planning to execution." Proceedings of the National Academy of Sciences 118, no. 6 (February 1, 2021): e2012658118. http://dx.doi.org/10.1073/pnas.2012658118.
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We studied correlated firing between motor thalamic and cortical cells in monkeys performing a delayed-response reaching task. Simultaneous recording of thalamocortical activity revealed that around movement onset, thalamic cells were positively correlated with cell activity in the primary motor cortex but negatively correlated with the activity of the premotor cortex. The differences in the correlation contrasted with the average neural responses, which were similar in all three areas. Neuronal correlations reveal functional cooperation and opposition between the motor thalamus and distinct motor cortical areas with specific roles in planning vs. performing movements. Thus, by enhancing and suppressing motor and premotor firing, the motor thalamus can facilitate the transition from a motor plan to execution.
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Villalba, Rosa M., Joseph A. Behnke, Jean-Francois Pare, and Yoland Smith. "Comparative Ultrastructural Analysis of Thalamocortical Innervation of the Primary Motor Cortex and Supplementary Motor Area in Control and MPTP-Treated Parkinsonian Monkeys." Cerebral Cortex 31, no. 7 (March 2, 2021): 3408–25. http://dx.doi.org/10.1093/cercor/bhab020.
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Abstract The synaptic organization of thalamic inputs to motor cortices remains poorly understood in primates. Thus, we compared the regional and synaptic connections of vGluT2-positive thalamocortical glutamatergic terminals in the supplementary motor area (SMA) and the primary motor cortex (M1) between control and MPTP-treated parkinsonian monkeys. In controls, vGluT2-containing fibers and terminal-like profiles invaded layer II–III and Vb of M1 and SMA. A significant reduction of vGluT2 labeling was found in layer Vb, but not in layer II–III, of parkinsonian animals, suggesting a potential thalamic denervation of deep cortical layers in parkinsonism. There was a significant difference in the pattern of synaptic connectivity in layers II–III, but not in layer Vb, between M1 and SMA of control monkeys. However, this difference was abolished in parkinsonian animals. No major difference was found in the proportion of perforated versus macular post-synaptic densities at thalamocortical synapses between control and parkinsonian monkeys in both cortical regions, except for a slight increase in the prevalence of perforated axo-dendritic synapses in the SMA of parkinsonian monkeys. Our findings suggest that disruption of the thalamic innervation of M1 and SMA may underlie pathophysiological changes of the motor thalamocortical loop in the state of parkinsonism.
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Kadmon Harpaz, Naama, David Ungarish, Nicholas G. Hatsopoulos, and Tamar Flash. "Movement Decomposition in the Primary Motor Cortex." Cerebral Cortex 29, no. 4 (April 13, 2018): 1619–33. http://dx.doi.org/10.1093/cercor/bhy060.
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Abstract A complex action can be described as the composition of a set of elementary movements. While both kinematic and dynamic elements have been proposed to compose complex actions, the structure of movement decomposition and its neural representation remain unknown. Here, we examined movement decomposition by modeling the temporal dynamics of neural populations in the primary motor cortex of macaque monkeys performing forelimb reaching movements. Using a hidden Markov model, we found that global transitions in the neural population activity are associated with a consistent segmentation of the behavioral output into acceleration and deceleration epochs with directional selectivity. Single cells exhibited modulation of firing rates between the kinematic epochs, with abrupt changes in spiking activity timed with the identified transitions. These results reveal distinct encoding of acceleration and deceleration phases at the level of M1, and point to a specific pattern of movement decomposition that arises from the underlying neural activity. A similar approach can be used to probe the structure of movement decomposition in different brain regions, possibly controlling different temporal scales, to reveal the hierarchical structure of movement composition.
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Mohn, Jennifer L., Joshua D. Downer, Kevin N. O’Connor, Jeffrey S. Johnson, and Mitchell L. Sutter. "Choice-related activity and neural encoding in primary auditory cortex and lateral belt during feature-selective attention." Journal of Neurophysiology 125, no. 5 (May 1, 2021): 1920–37. http://dx.doi.org/10.1152/jn.00406.2020.
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We recorded from primary and secondary auditory cortex while monkeys performed a nonspatial feature attention task. Both areas exhibited rate-based choice-related activity. The manifestation of choice-related activity was attention dependent, suggesting that choice-related activity in auditory cortex does not simply reflect arousal or motor influences but relates to the specific perceptual choice.
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Mountcastle, Vernon B., Pradeep P. Atluri, and Ranulfo Romo. "Selective Output-discriminative Signals in the Motor Cortex of Waking Monkeys." Cerebral Cortex 2, no. 4 (1992): 277–94. http://dx.doi.org/10.1093/cercor/2.4.277.
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Stepniewska, Iwona, Todd M. Preuss, and Jon H. Kaas. "Thalamic connections of the primary motor cortex (M1) of owl monkeys." Journal of Comparative Neurology 349, no. 4 (November 22, 1994): 558–82. http://dx.doi.org/10.1002/cne.903490405.
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McCarthy, G., C. C. Wood, and T. Allison. "Cortical somatosensory evoked potentials. I. Recordings in the monkey Macaca fascicularis." Journal of Neurophysiology 66, no. 1 (July 1, 1991): 53–63. http://dx.doi.org/10.1152/jn.1991.66.1.53.
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1. The anatomic generators of somatosensory evoked potentials (SEPs) to median nerve stimulation in the 10- to 30-ms latency range were investigated in monkeys (Macaca fascicularis) by means of cortical-surface and laminar recordings. 2. Three groups of SEPs evoked by stimulation of the contralateral median nerve were recorded from the hand representation area of sensorimotor cortex: P10-N20, recorded anterior to the central sulcus (CS); N10-P20, recorded posterior to the CS; and P12-N25, recorded near the CS. These potentials were similar in morphology and surface distribution whether the animal was awake or anesthetized. 3. P10-N20 exhibited a polarity inversion to N10-P20 across the CS, both in cortical-surface recordings and in laminar recordings within cortex and white matter of motor and somatosensory cortex. In contrast, P10-N20 and N10-P20 did not exhibit polarity inversion in recordings from the surface and white matter of the crowns of motor and somatosensory cortex, respectively. These results strongly suggest that these potentials are produced by a tangential generator located in the posterior wall of the CS, primarily in area 3b of somatosensory cortex. 4. P12-N25 was largest over the hand area of somatosensory cortex and showed polarity inversion across the crown of somatosensory cortex but not across the crown of motor cortex or across the walls of the CS, suggesting that P12-N25 is due to a radially oriented generator located in areas 1 and 2 of somatosensory cortex. 5. P10-N20 and P12-N25 are thought to be equivalent to the “primary evoked response” recorded from somatosensory cortex of other mammals. 6. These results are very similar to those obtained in human cortical-surface recordings and demonstrate that the monkey P10-N20, N10-P20, and P12-N25 potentials correspond to the human P20-N30, N20-P30, and P25-N35 potentials, respectively. The only appreciable difference in human and monkey SEPs is that the monkey P12-N25 appears to be generated in areas 1 and 2, whereas the human P25-N35 appears to be generated only in area 1. 7. There was no evidence of locally generated activity in areas 3a and 4.
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Port, Nicholas L., Wolfgang Kruse, Daeyeol Lee, and Apostolos P. Georgopoulos. "Motor Cortical Activity during Interception of Moving Targets." Journal of Cognitive Neuroscience 13, no. 3 (April 1, 2001): 306–18. http://dx.doi.org/10.1162/08989290151137368.
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The single-unit activity of 831 cells was recorded in the arm area of the motor cortex of tow monkeys while the monkeys intercepted a moving visual stimulus (interception task) or remained immobile during presentation of the same moving stimulus (no-go task). The moving target traveled on an oblique path from either lower corner of a screen toward the vertical meridian, and its movement time (0.5,1.0, or 1.5 sec) and velocity profile (accelerating, decelerating, or constant velocity) were pseudorandomly varied. The moving target had to be intercepted within 130 msec of target arrival at an interception point. By comparing motor cortical activity at the single-neuron tasks, we tested whether information about parameters of moving target is represented in the primary motor cortex to generate appropriate motor responses. A substantial number of neurons displayed modulation of their activity during the no-go task, and this activity was often affected by the stimulus parameters. These results suggest a role of motor cortex in specifying the timing of movement initiation based on information about target motion. In addition, there was a lack of systematic relation between the onset times of neural activity in the interception and no-go task, suggesting that processing of information concerning target motion and generation of hand movement occurs in parallel. Finally, the activity in the most motor cortical neurons was modulated according to an estimate of the time-to-target interception, raising the possibility that time-to-interception may be coded in the motor cortical activity.
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Baizer, Joan S., Ines Kralj-Hans, and Mitchell Glickstein. "Cerebellar Lesions and Prism Adaptation in Macaque Monkeys." Journal of Neurophysiology 81, no. 4 (April 1, 1999): 1960–65. http://dx.doi.org/10.1152/jn.1999.81.4.1960.
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Cerebellar lesions and prism adaptation in Macaque monkeys. If a laterally displacing prism is placed in front of one eye of a person or monkey with the other eye occluded, they initially will point to one side of a target that is located directly in front of them. Normally, people and monkeys adapt easily to the displaced vision and correct their aim after a few trials. If the prism then is removed, there is a postadaptation shift in which the subject misses the target and points in the opposite direction for a few trials. We tested five Macaque monkeys for their ability to adapt to a laterally displacing prism and to show the expected postadaptation shift. When tested as normals, all five animals showed the typical pattern of adaptation and postadaptation shift. Like human subjects, the monkeys also showed complete interocular transfer of the adaptation but no transfer of the adaptation between the two arms. When preoperative training and testing was complete, we made lesions of various target areas on the cerebellar cortex. A cerebellar lesion that included the dorsal paraflocculus and uvula abolished completely the normal prism adaptation for the arm ipsilateral to the lesion in one of the five monkeys. The other four animals retained the ability to prism-adapt normally and showed the expected postadaptation shift. In the one case in which the lesion abolished prism adaptation, the damage included Crus I and II, paramedian lobule and the dorsal paraflocculus of the cerebellar hemispheres as well as lobule IX, of the vermis. Thus in this case, the lesion included virtually all the cerebellar cortex that receives mossy-fiber visual information relayed via the pontine nuclei from the cerebral cortex. The other four animals had damage to lobule V, the classical anterior lobe arm area and/or vermian lobules VI/VII, the oculomotor region. When tested postoperatively, some of these animals showed a degree of ataxia equivalent to that of the case in which prism adaptation was affected, but prism adaptation and the postadaptation shift remained normal. We conclude that in addition to its role in long-term motor learning and reflex adaptation, the region of the cerebellum that was ablated also may be a critical site for a short-term motor memory. Prism adaptation seems to involve a region of the cerebellum that receives a mossy-fiber visual error signal and probably a corollary discharge of the movement.
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Ludvig, Nandor, Hai M. Tang, Shirn L. Baptiste, Geza Medveczky, Jonathan K. Vaynberg, Jacqueline Vazquez-DeRose, Dimitre G. Stefanov, et al. "Long-term behavioral, electrophysiological, and neurochemical monitoring of the safety of an experimental antiepileptic implant, the muscimol-delivering Subdural Pharmacotherapy Device in monkeys." Journal of Neurosurgery 117, no. 1 (July 2012): 162–75. http://dx.doi.org/10.3171/2012.4.jns111488.
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Object The authors evaluated the extent to which the Subdural Pharmacotherapy Device (SPD), chronically implanted over the frontal cortex to perform periodic, localized muscimol-delivery/CSF removal cycles, affects overall behavior, motor performance, electroencephalography (EEG) activity, and blood and CSF neurochemistry in macaque monkeys. Methods Two monkeys were used to adjust methodology and 4 monkeys were subjected to comprehensive testing. Prior to surgery, the animals' behavior in a large test chamber was monitored, and the motor skills required to remove food pellets from food ports located on the walls of the chamber were determined. The monkeys underwent implantation of the subdural and extracranial SPD units. The subdural unit, a silicone strip integrating EEG electrodes and fluid-exchange ports, was positioned over the right frontal cortex. The control unit included a battery-powered, microprocessor-regulated dual minipump and radiofrequency module secured to the cranium. After implantation, the SPD automatically performed periodic saline or muscimol (1.0 mM) deliveries at 12-hour intervals, alternating with local CSF removals at 6-hour intervals. The antiepileptic efficacy of this muscimol concentration was verified by demonstrating its ability to prevent focal acetylcholine-induced seizures. During SPD treatment, the monkeys' behavior and motor performance were again monitored, and the power spectrum of their radiofrequency-transmitted EEG recordings was analyzed. Serum and CSF muscimol levels were measured with high-performance liquid chromatography electrochemical detection, and CSF protein levels were measured with turbidimetry. Results The SPD was well tolerated in all monkeys for up to 11 months. The behavioral study revealed that during both saline and muscimol SPD treatment, the monkeys could achieve the maximum motor performance of 40 food-pellet removals per session, as before surgery. The EEG study showed that local EEG power spectra were not affected by muscimol treatment with SPD. The neurochemical study demonstrated that the administration of 1.0 mM muscimol into the neocortical subarachnoid space led to no detectable levels of this compound in the blood and cisternal CSF, as measured 1–125 minutes after delivery. Total protein levels were within the normal range in the cisternal CSF, but protein levels in the cortical-site CSF were significantly higher than normal: 361 ± 81.6 mg/dl. Abrupt discontinuation of 3-month, periodic, subdural muscimol treatments induced withdrawal seizures, which could be completely prevented by gradually tapering off the subdural muscimol concentration from 1.0 mM to 0.12–0.03 mM over a period of 2 weeks. The monkeys' general health and weight were maintained. Infection occurred only in one monkey 9 months after surgery. Conclusions Long-term, periodic, transmeningeal muscimol delivery with the SPD is essentially a safe procedure. If further improved and successfully adapted for use in humans, the SPD can be used for the treatment of intractable focal neocortical epilepsy affecting approximately 150,000 patients in the US.
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Tankus, Ariel, and Itzhak Fried. "Visuomotor Coordination and Motor Representation by Human Temporal Lobe Neurons." Journal of Cognitive Neuroscience 24, no. 3 (March 2012): 600–610. http://dx.doi.org/10.1162/jocn_a_00160.
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The division of cortical visual processing into distinct dorsal and ventral streams is a key concept in primate neuroscience [Goodale, M. A., & Milner, A. D. Separate visual pathways for perception and action. Trends in Neurosciences, 15, 20–25, 1992; Steele, G., Weller, R., & Cusick, C. Cortical connections of the caudal subdivision of the dorsolateral area (V4) in monkeys. Journal of Comparative Neurology, 306, 495–520, 1991]. The ventral stream is usually characterized as a “What” pathway, whereas the dorsal stream is implied in mediating spatial perception (“Where”) and visually guided actions (“How”). A subpathway emerging from the dorsal stream and projecting to the medial-temporal lobe has been identified [Kravitz, D. J., Saleem, K. S., Baker, C. I., & Mishkin, M. A new neural framework for visuospatial processing. Nature Reviews Neuroscience, 12, 217–230, 2011; Cavada, C., & Goldman-Raiuc, P. S. Posterior parietal cortex in rhesus monkey: I. Parcellation of areas based on distinctive limbic and sensory cortico-cortical connections. Journal of Comparative Neurology, 287, 393–421, 1989]. The current article studies the coordination of visual information typically associated with the dorsal stream (“Where”), with planned movements, focusing on the temporal lobe. We recorded extracellular activity from 565 cells in the human medial-temporal and frontal lobes while 13 patients performed cued hand movements with visual feedback (visuomotor task), without feedback (motor task), or observed visual feedback without motor movement (visual-only task). We discovered two different neural populations in the human medial-temporal lobe. One consists of motor-like neurons representing hand position, speed or acceleration during the motor task but not during the visuomotor or visual tasks. The other is specific to the parahippocampal gyrus (an area known to process visual motion [Gur, M., & Snodderly, D. M. Direction selectivity in V1 of alert monkeys: Evidence for parallel pathways for motion processing. Journal of Physiology, 585, 383–400, 2007; Sato, N., & Nakamura, K. Visual response properties of neurons in the parahippocampal cortex of monkeys. Journal of Neurophysiology, 90, 876–886, 2003]) and encodes speed, acceleration, or direction of hand movements, but only during the visuomotor task: neither during visual-only nor during motor tasks. These findings suggest a functional basis for the anatomical subpathway between the dorsal stream and the medial-temporal lobe. Similar to the recent expansion of the motor control process into the sensory cortex [Matyas, F., Sreenivasan, V., Marbach, F., Wacongne, C., Barsy, B., Mateo, C., et al. Motor control by sensory cortex. Science, 330, 1240–1243, 2010], our findings render the human medial-temporal lobe an important junction in the process of planning and execution of motor acts whether internally or externally (visually) driven. Thus, the medial-temporal lobe might serve as an integration node between the two processing streams. Our findings thus shed new light on the brain mechanisms underlying visuomotor coordination which is a crucial capacity for everyday survival, whether it is identifying and picking up food, sliding a key into a lock, driving a vehicle, or escaping a predator.
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Umeda, Tatsuya, Tadashi Isa, and Yukio Nishimura. "The somatosensory cortex receives information about motor output." Science Advances 5, no. 7 (July 2019): eaaw5388. http://dx.doi.org/10.1126/sciadv.aaw5388.
Full textAbstract:
During voluntary movement, the somatosensory system not only passively receives signals from the external world but also actively processes them via interactions with the motor system. However, it is still unclear how and what information the somatosensory system receives during movement. Using simultaneous recordings of activities of the primary somatosensory cortex (S1), the motor cortex (MCx), and an ensemble of afferent neurons in behaving monkeys combined with a decoding algorithm, we reveal the temporal profiles of signal integration in S1. While S1 activity before movement initiation is accounted for by MCx activity alone, activity during movement is accounted for by both MCx and afferent activities. Furthermore, premovement S1 activity encodes information about imminent activity of forelimb muscles slightly after MCx does. Thus, S1 receives information about motor output before the arrival of sensory feedback signals, suggesting that S1 executes online processing of somatosensory signals via interactions with the anticipatory information.
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Ishida, Hiroaki, Katsumi Nakajima, Masahiko Inase, and Akira Murata. "Shared Mapping of Own and Others' Bodies in Visuotactile Bimodal Area of Monkey Parietal Cortex." Journal of Cognitive Neuroscience 22, no. 1 (January 2010): 83–96. http://dx.doi.org/10.1162/jocn.2009.21185.
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Parietal cortex contributes to body representations by integrating visual and somatosensory inputs. Because mirror neurons in ventral premotor and parietal cortices represent visual images of others' actions on the intrinsic motor representation of the self, this matching system may play important roles in recognizing actions performed by others. However, where and how the brain represents others' bodies and correlates self and other body representations remain unclear. We expected that a population of visuotactile neurons in simian parietal cortex would represent not only own but others' body parts. We first searched for parietal visuotactile bimodal neurons in the ventral intraparietal area and area 7b of monkeys, and then examined the activity of these neurons while monkeys were observing visual or tactile stimuli placed on the experimenter's body parts. Some bimodal neurons with receptive fields (RFs) anchored on the monkey's body exhibited visual responses matched to corresponding body parts of the experimenter, and visual RFs near that body part existed in the peripersonal space within approximately 30 cm from the body surface. These findings suggest that the brain could use self representation as a reference for perception of others' body parts in parietal cortex. These neurons may contribute to spatial matching between the bodies of the self and others in both action recognition and imitation.
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Berdyyeva, Tamara K., and Carl R. Olson. "Rank Signals in Four Areas of Macaque Frontal Cortex During Selection of Actions and Objects in Serial Order." Journal of Neurophysiology 104, no. 1 (July 2010): 141–59. http://dx.doi.org/10.1152/jn.00639.2009.
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Neurons in several areas of monkey frontal cortex exhibit ordinal position (rank) selectivity during the performance of serial order tasks. It has been unclear whether rank selectivity or the dependence of rank selectivity on task context varies across the areas of frontal cortex. To resolve this issue, we recorded from neurons in the supplementary motor area (SMA), presupplementary motor area (pre-SMA), supplementary eye field (SEF), and dorsolateral prefrontal cortex (dlPFC) as monkeys performed two oculomotor tasks, one requiring the selection of three actions in sequence and the other requiring the selection of three objects in sequence. We found that neurons representing all ranks were present in all areas. Only to a moderate degree did the prevalence and nature of rank selectivity vary from area to area. The two most prominent inter-area differences involved a lower prevalence of rank selectivity in the dlPFC than in the other areas and a higher proportion of neurons preferring late ranks in the SMA and SEF than in the other areas. Neurons in all four areas are rank generalists in the sense of favoring the same rank in both the serial action task and the serial object task.
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Murphy, John T., Hon C. Kwan, and Yiu C. Wong. "Cross Correlation Studies in Primate Motor Cortex: Event Related Correlation." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 12, no. 1 (February 1985): 24–30. http://dx.doi.org/10.1017/s0317167100046539.
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ABSTRACT:Simultaneous extracellular unit recordings were made from each cell of 237 pairs in two awake monkeys, during a voluntary reaching movement of the forelimb. The cells were located in contralateral precentral cortex and functionally coupled to single forelimb joints, as indicated by intracortical microstimulation and passive sensory stimulation. Cross correlation analysis showed that 72 of these pairs exhibited significant event-related correlation over periods of up to 780 ms, comparable to and coincident with the forelimb movement. Spatial analysis showed that such correlation extended across contiguous portions of all four forelimb joint zones of precentral cortex, over distances up to 3.5 mm. No preferred direction of correlation was observed. The data confirm the previously described nested organization of the forelimb area of precentral cortex. Findings are discussed in terms of mechanisms by which columns of neurons in motor cortex participate in the reaching movement.
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Merten, Katharina, and Andreas Nieder. "Comparison of abstract decision encoding in the monkey prefrontal cortex, the presupplementary, and cingulate motor areas." Journal of Neurophysiology 110, no. 1 (July 1, 2013): 19–32. http://dx.doi.org/10.1152/jn.00686.2012.
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Deciding between alternatives is a critical element of flexible behavior. Perceptual decisions have been studied extensively in an action-based framework. Recently, we have shown that abstract perceptual decisions are encoded in prefrontal cortex (PFC) neurons ( Merten and Nieder 2012 ). However, the role of other frontal cortex areas remained elusive. Here, we trained monkeys to perform a rule-based visual detection task that disentangled abstract perceptual decisions from motor preparation. We recorded the single-neuron activity in the presupplementary (preSMA) and the rostral part of the cingulate motor area (CMAr) and compared it to the results previously found in the PFC. Neurons in both areas traditionally identified with motor planning process the abstract decision independently of any motor preparatory activity by similar mechanisms as the PFC. A larger proportion of decision neurons and a higher strength of decision encoding was found in the preSMA than in the PFC. Neurons in both areas reliably predicted the monkeys' decisions. The fraction of CMAr decision neurons and their strength of the decision encoding were comparable to the PFC. Our findings highlight the role of both preSMA and CMAr in abstract cognitive processing and emphasize that both frontal areas encode decisions prior to the preparation of a motor output.
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Rao, Naveen G., and John P. Donoghue. "Cue to action processing in motor cortex populations." Journal of Neurophysiology 111, no. 2 (January 15, 2014): 441–53. http://dx.doi.org/10.1152/jn.00274.2013.
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The primary motor cortex (MI) commands motor output after kinematics are planned from goals, thought to occur in a larger premotor network. However, there is a growing body of evidence that MI is involved in processes beyond action generation, and neuronal subpopulations may perform computations related to cue-to-action processing. From multielectrode array recordings in awake behaving Macaca mulatta monkeys, our results suggest that early MI ensemble activity during goal-directed reaches is driven by target information when cues are closely linked in time to action. Single-neuron activity spanned cue presentation to movement, with the earliest responses temporally aligned to cue and the later responses better aligned to arm movements. Population decoding revealed that MI's coding of cue direction evolved temporally, likely going from cue to action generation. We confirmed that a portion of MI activity is related to visual target processing by showing changes in MI activity related to the extinguishing of a continuously pursued visual target. These findings support a view that MI is an integral part of a cue-to-action network for immediate responses to environmental stimuli.
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Naselaris, Thomas, Hugo Merchant, Bagrat Amirikian, and Apostolos P. Georgopoulos. "Large-Scale Organization of Preferred Directions in the Motor Cortex. I. Motor Cortical Hyperacuity for Forward Reaching." Journal of Neurophysiology 96, no. 6 (December 2006): 3231–36. http://dx.doi.org/10.1152/jn.00487.2006.
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We used statistical methods for spherical density estimation to evaluate the distribution of preferred directions of motor cortical cells recorded from monkeys making reaching movements in 3D space. We found that this distribution, although broad enough to represent the entire 3D continuum of reaching directions, exhibited an enrichment for reaching forward from the body and, to a lesser degree, for reaching backward toward the body. The distribution of preferred directions of cells in the motor cortex may have important implications for motor cortical function and for the decoding of arm trajectories from population activity.
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Chao, Zenas C., Masahiro Sawada, Tadashi Isa, and Yukio Nishimura. "Dynamic Reorganization of Motor Networks During Recovery from Partial Spinal Cord Injury in Monkeys." Cerebral Cortex 29, no. 7 (July 27, 2018): 3059–73. http://dx.doi.org/10.1093/cercor/bhy172.
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Abstract After spinal cord injury (SCI), the motor-related cortical areas can be a potential substrate for functional recovery in addition to the spinal cord. However, a dynamic description of how motor cortical circuits reorganize after SCI is lacking. Here, we captured the comprehensive dynamics of motor networks across SCI in a nonhuman primate model. Using electrocorticography over the sensorimotor areas in monkeys, we collected broadband neuronal signals during a reaching-and-grasping task at different stages of recovery of dexterous finger movements after a partial SCI at the cervical levels. We identified two distinct network dynamics: grasping-related intrahemispheric interactions from the contralesional premotor cortex (PM) to the contralesional primary motor cortex (M1) in the high-γ band (>70 Hz), and motor-preparation-related interhemispheric interactions from the contralesional to ipsilesional PM in the α and low-β bands (10–15 Hz). The strengths of these networks correlated to the time course of behavioral recovery. The grasping-related network showed enhanced activation immediately after the injury, but gradually returned to normal while the strength of the motor-preparation-related network gradually increased. Our findings suggest a cortical compensatory mechanism after SCI, where two interdependent motor networks redirect activity from the contralesional hemisphere to the other hemisphere to facilitate functional recovery.
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Murray, G. M., and B. J. Sessle. "Functional properties of single neurons in the face primary motor cortex of the primate. II. Relations with trained orofacial motor behavior." Journal of Neurophysiology 67, no. 3 (March 1, 1992): 759–74. http://dx.doi.org/10.1152/jn.1992.67.3.759.
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1. The previous paper has described in detail the input and output features of single neurons located at sites within primate face motor cortex from which intracortical microstimulation (ICMS, less than or equal to 20 microA) evoked tongue movements at the lowest threshold ("tongue-MI" sites); for comparative purposes, we also reported on the input and output features of a smaller number of neurons recorded at sites from which ICMS could evoke jaw movements ("jaw-MI" sites), facial movements ("face-MI" sites), or, at a few sites, tongue movements and, at the same threshold intensity, either a jaw movement or a facial movement. 2. Our findings of an extensive and diverse representation of sites within face motor cortex of monkeys for the generation of elemental components of tongue movement, and the relatively few sites from which jaw-closing movements could be evoked, were consistent with our recent observations that reversible, cooling-induced inactivation of the face motor cortex severely impaired the performance by monkeys of a tongue-protrusion task but had only relatively minor effects on the performance of a biting task. In an attempt to establish a neuronal correlate for these different behavioral relations, the present study has documented the task-related activities of those single neurons that were characterized in the previous paper in terms of afferent input and ICMS-defined output features. 3. Each task required the development and maintenance by each monkey of a fixed force level for a minimum period of time to obtain a fruit-juice reward. During one or both of these tasks, we characterized the activities of 231 single face motor cortical neurons that were located at the above-mentioned ICMS-defined sites. Neurons were said to be related to a particular task if they showed statistically significant differences in firing rates during the task in comparison with a control pretrial period (PTP). 4. In tongue-MI, there was a significantly higher proportion of neurons (63% of 156 neurons tested) that were related to the tongue-protrusion task than to the biting task (15% of 65). However, in jaw-MI the proportion of neurons that were biting task-related (63% of 19) was significantly higher than the proportion related to the tongue-protrusion task (11% of 9); the proportion of biting task-related neurons at ICMS-defined jaw-closing sites was also higher than that at jaw-opening sites.(ABSTRACT TRUNCATED AT 400 WORDS)
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Andersen, Richard A., and David Zipser. "The role of the posterior parietal cortex in coordinate transformations for visual–motor integration." Canadian Journal of Physiology and Pharmacology 66, no. 4 (April 1, 1988): 488–501. http://dx.doi.org/10.1139/y88-078.
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Lesion to the posterior parietal cortex in monkeys and humans produces spatial deficits in movement and perception. In recording experiments from area 7a, a cortical subdivision in the posterior parietal cortex in monkeys, we have found neurons whose responses are a function of both the retinal location of visual stimuli and the position of the eyes in the orbits. By combining these signals area 7a neurons code the location of visual stimuli with respect to the head. However, these cells respond over only limited ranges of eye positions (eye-position-dependent coding). To code location in craniotopic space at all eye positions (eye-position-independent coding) an additional step in neural processing is required that uses information distributed across populations of area 7a neurons. We describe here a neural network model, based on back-propagation learning, that both demonstrates how spatial location could be derived from the population response of area 7a neurons and accurately accounts for the observed response properties of these neurons.
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Graziano, Michael S. A., Tyson N. S. Aflalo, and Dylan F. Cooke. "Arm Movements Evoked by Electrical Stimulation in the Motor Cortex of Monkeys." Journal of Neurophysiology 94, no. 6 (December 2005): 4209–23. http://dx.doi.org/10.1152/jn.01303.2004.
Full textAbstract:
Electrical stimulation of the motor cortex in monkeys can evoke complex, multijoint movements including movements of the arm and hand. In this study, we examined these movements in detail and tested whether they showed adaptability to differing circumstances such as to a weight added to the hand. Electrical microstimulation was applied to motor cortex using pulse trains of 500-ms duration (matching the approximate duration of a reach). Arm movement was measured using a high-resolution three-dimensional tracking system. Movement latencies averaged 80.2 ms. Speed profiles were typically smooth and bell-shaped, and the peak speed covaried with movement distance. Stimulation generally evoked a specific final hand position. The convergence of the hand from disparate starting positions to a narrow range of final positions was statistically significant for every site tested (91/91). When a weight was fixed to the hand, for some stimulation sites (74%), the evoked movement appeared to compensate for the weight in that the hand was lifted to a similar final location. For other stimulation sites (26%), the weight caused a significant reduction in final hand height. For about one-half of the sites (54%), the variation in movement of each joint appeared to compensate for the variation in the other joints in a manner that stabilized the hand in a restricted region of space. These findings suggest that at least some of the stimulation-evoked movements reflect relatively high-level, adaptable motor plans.
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Umilta, M. A., T. Brochier, R. L. Spinks, and R. N. Lemon. "Simultaneous Recording of Macaque Premotor and Primary Motor Cortex Neuronal Populations Reveals Different Functional Contributions to Visuomotor Grasp." Journal of Neurophysiology 98, no. 1 (July 2007): 488–501. http://dx.doi.org/10.1152/jn.01094.2006.
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To understand the relative contributions of primary motor cortex (M1) and area F5 of the ventral premotor cortex (PMv) to visually guided grasp, we made simultaneous multiple electrode recordings from the hand representations of these two areas in two adult macaque monkeys. The monkeys were trained to fixate, reach out and grasp one of six objects presented in a pseudorandom order. In M1 326 task-related neurons, 104 of which were identified as pyramidal tract neurons, and 138 F5 neurons were analyzed as separate populations. All three populations showed activity that distinguished the six objects grasped by the monkey. These three populations responded in a manner that generalized across different sets of objects. F5 neurons showed object/grasp related tuning earlier than M1 neurons in the visual presentation and premovement periods. Also F5 neurons generally showed a greater preference for particular objects/grasps than did M1 neurons. F5 neurons remained tuned to a particular grasp throughout both the premovement and reach-to-grasp phases of the task, whereas M1 neurons showed different selectivity during the different phases. We also found that different types of grasp appear to be represented by different overall levels of activity within the F5-M1 circuit. Altogether these properties are consistent with the notion that F5 grasping-related neurons play a role in translating visual information about the physical properties of an object into the motor commands that are appropriate for grasping, and which are elaborated within M1 for delivery to the appropriate spinal machinery controlling hand and digit muscles.