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1
Leopold, David A., Gillian Rhodes, Kai-Markus Müller e Linda Jeffery. "The dynamics of visual adaptation to faces". Proceedings of the Royal Society B: Biological Sciences 272, n. 1566 (5 maggio 2005): 897–904. http://dx.doi.org/10.1098/rspb.2004.3022.
Testo completoAbstract (sommario):
Several recent demonstrations using visual adaptation have revealed high-level aftereffects for complex patterns including faces. While traditional aftereffects involve perceptual distortion of simple attributes such as orientation or colour that are processed early in the visual cortical hierarchy, face adaptation affects perceived identity and expression, which are thought to be products of higher-order processing. And, unlike most simple aftereffects, those involving faces are robust to changes in scale, position and orientation between the adapting and test stimuli. These differences raise the question of how closely related face aftereffects are to traditional ones. Little is known about the build-up and decay of the face aftereffect, and the similarity of these dynamic processes to traditional aftereffects might provide insight into this relationship. We examined the effect of varying the duration of both the adapting and test stimuli on the magnitude of perceived distortions in face identity. We found that, just as with traditional aftereffects, the identity aftereffect grew logarithmically stronger as a function of adaptation time and exponentially weaker as a function of test duration. Even the subtle aspects of these dynamics, such as the power-law relationship between the adapting and test durations, closely resembled that of other aftereffects. These results were obtained with two different sets of face stimuli that differed greatly in their low-level properties. We postulate that the mechanisms governing these shared dynamics may be dissociable from the responses of feature-selective neurons in the early visual cortex.
2
Petersik, J. Timothy. "Buildup and Decay of a Three-Dimensional Rotational Aftereffect Obtained with a Three-Dimensional Figure". Perception 31, n. 7 (luglio 2002): 825–36. http://dx.doi.org/10.1068/p3358.
Testo completoAbstract (sommario):
Gaps in past literature have raised questions regarding the kinds of stimuli that can lead to three-dimensional (3-D) rotation aftereffects. Further, the characteristics of the buildup and decay of such aftereffects are not clear. In the present experiments, rotation aftereffects were generated by projections of cube-like stimuli whose dynamic perspective motions gave rise to the perception of rotation in unambiguous directions; test stimuli consisted of similar cubes whose rotation directions were ambiguous. In experiment 1, the duration of the adaptation stimulus was varied and it was found that the 3-D rotation aftereffect develops with a time constant of approximately 26 s. In experiment 2, the duration between adaptation and testing was varied. It was found that the 3-D rotation aftereffect has a decay constant of about 9 s, similar to that observed with 2-D motion aftereffects. Experiment 3 showed that the rotation aftereffects were not simple depth aftereffects. To account for these aftereffects and related data, a modification of an existing neural-network model is suggested.
3
Delorme, André. "Dichoptically Viewed Colour Aftereffects Produced by Monocular Adaptation". Perception 23, n. 8 (agosto 1994): 957–64. http://dx.doi.org/10.1068/p230957.
Testo completoAbstract (sommario):
Colour aftereffects were observed in dichoptically viewed achromatic striped patterns after a 25 s period of monocular adaptation to an homogeneous coloured field of red, green, or blue. Three test conditions of dichoptic viewing were used. In condition 1, black line patterns were viewed dichoptically on fused white backgrounds. Stimuli used in condition 2 were similar except that they were white line patterns on black backgrounds. Last, condition 3 was realised with the same stimulus patterns utilised in condition 1, except that the mode of dichoptic viewing produced a juxtaposition rather than a fusion of the two white backgrounds containing the line patterns. Some colour aftereffect was obtained for each colour-adaptation condition and in each test condition. It consisted in a negative colour aftereffect (NCA) in the adapted eye (the colour seen was roughly the complementary of the adaptation colour) and/or a positive colour aftereffect (PCA) in the unadapted eye (the colour seen tended rather to be similar in hue to the adaptation colour). In fact, the following four kinds of responses were obtained: (i) two colour aftereffects, one seen by each eye, ie a NCA involving the adapted eye and a PCA involving the unadapted eye; (ii) a NCA involving the adapted eye only; (iii) a PCA involving the unadapted eye only; (iv) no colour aftereffect at all. Results obtained in different test conditions permitted us to assert that both kinds of colour aftereffect could be produced with white patterns on dark backgrounds as well as with black patterns on white backgrounds and did not require binocular fusion of the white backgrounds. Hypothetical physiological explanations of these aftereffects are available.
4
Wade, Nicholas J., e Charles M. M. De Weert. "Aftereffects in Binocular Rivalry". Perception 15, n. 4 (agosto 1986): 419–34. http://dx.doi.org/10.1068/p150419.
Testo completoAbstract (sommario):
Five experiments are reported in which the aftereffect paradigm was applied to binocular rivalry. In the first three experiments rivalry was between a vertical grating presented to the left eye and a horizontal grating presented to the right eye. In the fourth experiment the rivalry stimuli consisted of a rotating sectored disc presented to the left eye and a static concentric circular pattern presented to the right. In experiment 5 rivalry was between static radiating and circular patterns. The predominance durations were systematically influenced by direct (same eye) and indirect (interocular) adaptation in a manner similar to that seen for spatial aftereffects. Binocular adaptation produced an aftereffect that was significantly smaller than the direct aftereffect, but not significantly different from the indirect one. A model is developed to account for the results; it involves two levels of binocular interaction in addition to monocular channels. It is suggested that the site of spatial aftereffects is the same as that for binocular rivalry, rather than sequentially prior.
5
Calzolari, Elena, Elena Azañón, Matthew Danvers, Giuseppe Vallar e Matthew R. Longo. "Adaptation aftereffects reveal that tactile distance is a basic somatosensory feature". Proceedings of the National Academy of Sciences 114, n. 17 (10 aprile 2017): 4555–60. http://dx.doi.org/10.1073/pnas.1614979114.
Testo completoAbstract (sommario):
The stage at which processing of tactile distance occurs is still debated. We addressed this issue by implementing an adaptation-aftereffect paradigm with passive touch. We demonstrated the presence of a strong aftereffect, induced by the simultaneous presentation of pairs of tactile stimuli. After adaptation to two different distances, one on each hand, participants systematically perceived a subsequent stimulus delivered to the hand adapted to the smaller distance as being larger. We further investigated the nature of the aftereffects, demonstrating that they are orientation- and skin-region–specific, occur even when just one hand is adapted, do not transfer either contralaterally or across the palm and dorsum, and are defined in a skin-centered, rather than an external, reference frame. These characteristics of tactile distance aftereffects are similar to those of low-level visual aftereffects, supporting the idea that distance perception arises at early stages of tactile processing.
6
SAUL, ALAN B. "Visual cortical simple cells: Who inhibits whom". Visual Neuroscience 16, n. 4 (luglio 1999): 667–73. http://dx.doi.org/10.1017/s095252389916406x.
Testo completoAbstract (sommario):
Simple cells display a specific adaptation aftereffect when tested with drifting gratings. The onset of the response to each cycle of the grating is delayed after adapting, but the offset is unaffected. Testing with stationary bars whose luminance was modulated in time revealed that aftereffects occur only at certain points in both space and time. The aftereffects seen with moving stimuli were predicted from those seen with stationary stimuli. These adaptation experiments suggest a model that consists of mutually inhibitory simple cells that are in spatiotemporal quadrature. The inhibition is appropriately localized in space and time to create the observed aftereffects. In this model, inhibition onto direction-selective simple cells arises from simple cells with the same preferred direction.
7
Burgering, Merel A., Thijs van Laarhoven, Martijn Baart e Jean Vroomen. "Fluidity in the perception of auditory speech: Cross-modal recalibration of voice gender and vowel identity by a talking face". Quarterly Journal of Experimental Psychology 73, n. 6 (30 gennaio 2020): 957–67. http://dx.doi.org/10.1177/1747021819900884.
Testo completoAbstract (sommario):
Humans quickly adapt to variations in the speech signal. Adaptation may surface as recalibration, a learning effect driven by error-minimisation between a visual face and an ambiguous auditory speech signal, or as selective adaptation, a contrastive aftereffect driven by the acoustic clarity of the sound. Here, we examined whether these aftereffects occur for vowel identity and voice gender. Participants were exposed to male, female, or androgynous tokens of speakers pronouncing /e/, /ø/, (embedded in words with a consonant-vowel-consonant structure), or an ambiguous vowel halfway between /e/ and /ø/ dubbed onto the video of a male or female speaker pronouncing /e/ or /ø/. For both voice gender and vowel identity, we found assimilative aftereffects after exposure to auditory ambiguous adapter sounds, and contrastive aftereffects after exposure to auditory clear adapter sounds. This demonstrates that similar principles for adaptation in these dimensions are at play.
8
Reinhardt-Rutland, Anthony H. "Increasing-Loudness Aftereffect following Decreasing-Intensity Adaptation: Spectral Dependence in Interotic and Monotic Testing". Perception 27, n. 4 (aprile 1998): 473–82. http://dx.doi.org/10.1068/p270473.
Testo completoAbstract (sommario):
Listening to decreasing intensity leads to illusory increasing loudness afterwards. Evidence suggests that this increasing-loudness aftereffect may have a sensory component concerned with dynamic localisation. This was tested by comparing the spectral dependence of monotic aftereffect (adapting and testing one ear) with the spectral dependence of interotic aftereffect (adapting one ear and testing the other ear). Existence of the proposed component implies that monotic aftereffect should be more spectrally dependent than interotic aftereffect. Three listeners were exposed to a 1 kHz adapting stimulus. From responses of “growing softer” or “growing louder” to test stimuli changing in intensity, nulls were calculated; test carrier frequencies ranged from 0.5 kHz to 2 kHz. Confirming the hypothesis, monotic aftereffect was about three times as strong as interotic aftereffect for the 1 kHz test carrier frequency, while monotic and interotic aftereffects were comparable in magnitude for test carrier frequencies below about 0.8 kHz and above about 1.2 kHz. The latter residual aftereffects are attributed to cognitive processing, perhaps concerning response bias. Sensitivity did not vary systematically across conditions; this is consistent with evidence that changing intensity entails mainly direct processing. The results cannot be attributed to the loudness adaptation elicited by steady stimuli.
9
Roach, Neil W., e Paul V. McGraw. "Dynamics of Spatial Distortions Reveal Multiple Time Scales of Motion Adaptation". Journal of Neurophysiology 102, n. 6 (dicembre 2009): 3619–26. http://dx.doi.org/10.1152/jn.00548.2009.
Testo completoAbstract (sommario):
Prolonged exposure to consistent visual motion can significantly alter the perceived direction and speed of subsequently viewed objects. These perceptual aftereffects have provided invaluable tools with which to study the mechanisms of motion adaptation and draw inferences about the properties of underlying neural populations. Behavioral studies of the time course of motion aftereffects typically reveal a gradual process of adaptation spanning a period of multiple seconds. In contrast, neurophysiological studies have documented multiple motion adaptation effects operating over similar, or substantially faster (i.e., sub-second) time scales. Here we investigated motion adaptation by measuring time-dependent changes in the ability of moving stimuli to distort the perceived position of briefly presented static objects. The temporal dynamics of these motion-induced spatial distortions reveal the operation of two dissociable mechanisms of motion adaptation with differing properties. The first is rapid (subsecond), acts to limit the distortions induced by continuing motion, but is not sufficient to produce an aftereffect once the motion signal disappears. The second gradually accumulates over a period of seconds, does not modulate the size of distortions produced by continuing motion, and produces repulsive aftereffects after motion offset. These results provide new psychophysical evidence for the operation of multiple mechanisms of motion adaptation operating over distinct time scales.
10
Ehrenstein, Walter H. "Auditory Aftereffects following Simulated Motion Produced by Varying Interaural Intensity or Time". Perception 23, n. 10 (ottobre 1994): 1249–55. http://dx.doi.org/10.1068/p231249.
Testo completoAbstract (sommario):
Simulated auditory motion, ie step-ramp modulated interaural intensity (Δ I) or time (Δ t) was presented via headphones as an adapting stimulus (narrow-band signal of 1 kHz mean frequency). After adaptation, settings of a stationary test stimulus were systematically shifted in the opposite direction when the experimental parameter was Δ I, but not when it was Δ t. Further studies with Δ t motion with the use of mean frequencies of 100 Hz or 6 kHz showed an aftereffect only at 6 kHz. Unlike visual motion aftereffects, no counter-motion was observed; rather the test stimulus appeared stationary, but settings of its interaural midline were displaced in a direction opposite to the direction of adaptation (on average by 1.2 dB or 30 μs for Δ I-simulated and Δ I-simulated motion, respectively). This displacement effect decayed with time after adaptation. The frequency dependence found for Δ t motion suggests that the low-frequency mechanism of directional hearing that uses interaural ongoing-time (phase) differences is not able to adapt. The observed auditory aftereffects may be analogous to visual motion aftereffects since they are direction specific; however, because they lack apparent motion they also resemble disparity-specific stereoscopic aftereffects.
11
Bunday, Karen L., e Adolfo M. Bronstein. "Locomotor Adaptation and Aftereffects in Patients With Reduced Somatosensory Input Due to Peripheral Neuropathy". Journal of Neurophysiology 102, n. 6 (dicembre 2009): 3119–28. http://dx.doi.org/10.1152/jn.00304.2009.
Testo completoAbstract (sommario):
We studied 12 peripheral neuropathy patients (PNP) and 13 age-matched controls with the “broken escalator” paradigm to see how somatosensory loss affects gait adaptation and the release and recovery (“braking”) of the forward trunk overshoot observed during this locomotor aftereffect. Trunk displacement, foot contact signals, and leg electromyograms (EMGs) were recorded while subjects walked onto a stationary sled (BEFORE trials), onto the moving sled (MOVING or adaptation trials), and again onto the stationary sled (AFTER trials). PNP were unsteady during the MOVING trials, but this progressively improved, indicating some adaptation. During the after trials, 77% of control subjects displayed a trunk overshoot aftereffect but over half of the PNP (58%) did not. The PNP without a trunk aftereffect adapted to the MOVING trials by increasing distance traveled; subsequently this was expressed as increased distance traveled during the aftereffect rather than as a trunk overshoot. This clear separation in consequent aftereffects was not seen in the normal controls suggesting that, as a result of somatosensory loss, some PNP use distinctive strategies to negotiate the moving sled, in turn resulting in a distinct aftereffects. In addition, PNP displayed earlier than normal anticipatory leg EMG activity during the first after trial. Although proprioceptive inputs are not critical for the emergence or termination of the aftereffect, somatosensory loss induces profound changes in motor adaptation and anticipation. Our study has found individual differences in adaptive motor performance, indicative that PNP adopt different feed-forward gait compensatory strategies in response to peripheral sensory loss.
12
Brooks, Kevin R., Colin W. G. Clifford, Richard J. Stevenson, Jonathan Mond e Ian D. Stephen. "The high-level basis of body adaptation". Royal Society Open Science 5, n. 6 (giugno 2018): 172103. http://dx.doi.org/10.1098/rsos.172103.
Testo completoAbstract (sommario):
Prolonged visual exposure, or ‘adaptation’, to thin (wide) bodies causes a perceptual aftereffect such that subsequently seen bodies appear wider (thinner) than they actually are. Here, we conducted two experiments investigating the effect of rotating the orientation of the test stimuli by 90° from that of the adaptor. Aftereffects were maximal when adapting and test bodies had the same orientation. When they differed, the axis of the perceived distortion changed with the orientation of the body. Experiment 1 demonstrated a 58% transfer of the aftereffect across orientations. Experiment 2 demonstrated an even greater degree of aftereffect transfer when the influence of low-level mechanisms was reduced further by using adaptation and test stimuli with different sizes. These results indicate that the body aftereffect is mediated primarily by high-level object-based processes, with low-level retinotopic mechanisms playing only a minor role. The influence of these low-level processes is further reduced when test stimuli differ in size from adaptation stimuli.
13
Groen, Joris, e Peter J. Werkhoven. "Visuomotor Adaptation to Virtual Hand Position in Interactive Virtual Environments". Presence: Teleoperators and Virtual Environments 7, n. 5 (ottobre 1998): 429–46. http://dx.doi.org/10.1162/105474698565839.
Testo completoAbstract (sommario):
In virtual environments the virtual hand may not always be exactly aligned with the real hand. Such misalignment may cause an adaptation of the users' eye-hand coordination. Further, misalignment may cause a decrease in manipulation performance compared to aligned conditions. This experimental study uses a prism-adaptation paradigm to explore visuomotor adaptation to misaligned virtual hand position. Participants were immersed in an interactive virtual environment with a deliberately misaligned virtual hand position (a lateral shift of 10 cm). We carried out pointing tests with a nonvisible hand in the real world before (pretest) and after (posttest) immersion in the virtual world. A comparison of preand post-tests revealed aftereffects of the adaptation of eye-hand coordination in the opposite direction of the lateral shift (negative aftereffects). The magnitude of the aftereffect was 20% under stereoscopic viewing conditions. However, decreased manipulation performance in VE (speed/accuracy) during the immersion with misaligned hand conditions was not found.
14
Barraclough, Nick E., Rebecca H. Keith, Dengke Xiao, Mike W. Oram e David I. Perrett. "Visual Adaptation to Goal-directed Hand Actions". Journal of Cognitive Neuroscience 21, n. 9 (settembre 2009): 1805–19. http://dx.doi.org/10.1162/jocn.2008.21145.
Testo completoAbstract (sommario):
Prolonged exposure to visual stimuli, or adaptation, often results in an adaptation “aftereffect” which can profoundly distort our perception of subsequent visual stimuli. This technique has been commonly used to investigate mechanisms underlying our perception of simple visual stimuli, and more recently, of static faces. We tested whether humans would adapt to movies of hands grasping and placing different weight objects. After adapting to hands grasping light or heavy objects, subsequently perceived objects appeared relatively heavier, or lighter, respectively. The aftereffects increased logarithmically with adaptation action repetition and decayed logarithmically with time. Adaptation aftereffects also indicated that perception of actions relies predominantly on view-dependent mechanisms. Adapting to one action significantly influenced the perception of the opposite action. These aftereffects can only be explained by adaptation of mechanisms that take into account the presence/absence of the object in the hand. We tested if evidence on action processing mechanisms obtained using visual adaptation techniques confirms underlying neural processing. We recorded monkey superior temporal sulcus (STS) single-cell responses to hand actions. Cells sensitive to grasping or placing typically responded well to the opposite action; cells also responded during different phases of the actions. Cell responses were sensitive to the view of the action and were dependent upon the presence of the object in the scene. We show here that action processing mechanisms established using visual adaptation parallel the neural mechanisms revealed during recording from monkey STS. Visual adaptation techniques can thus be usefully employed to investigate brain mechanisms underlying action perception.
15
GOEDERT, KELLY M., ANDREW LEBLANC, SEN-WEI TSAI e ANNA M. BARRETT. "Asymmetrical Effects of Adaptation to Left- and Right-Shifting Prisms Depends on Pre-existing Attentional Biases". Journal of the International Neuropsychological Society 16, n. 5 (5 luglio 2010): 795–804. http://dx.doi.org/10.1017/s1355617710000597.
Testo completoAbstract (sommario):
AbstractProposals that adaptation with left-shifting prisms induces neglect-like symptoms in normal individuals rely on a dissociation between the postadaptation performance of individuals trained with left- versus right-shifting prisms (e.g., Colent, Pisella, & Rossetti, 2000). A potential problem with this evidence is that normal young adults have an a priori leftward bias (e.g., Jewell & McCourt, 2000). In Experiment 1, we compared the line bisection performance of young adults to that of aged adults, who as a group may lack a leftward bias in line bisection. Participants trained with both left- and right-shifting prisms. Consistent with our hypothesis, while young adults demonstrated aftereffects for left, but not right prisms, aged adults demonstrated reliable aftereffects for both prisms. In Experiment 2, we recruited a larger sample of young adults, some of whom were right-biased at baseline. We observed an interaction between baseline bias and prism-shift, consistent with the results of Experiment 1: Left-biased individuals showed a reduced aftereffect when training with right-shifting prisms and right-biased individuals showed a reduced aftereffect when training with left-shifting prisms. These results suggest that previous failures to find generalizable aftereffects with right-shifting prisms may be driven by participants’ baseline biases rather than specific effects of the prism itself. (JINS, 2010, 16, 795–804.)
16
Bestelmeyer, Patricia E. G., Bethan Williams, Jennifer J. Lawton, Maria-Elena Stefanou, Kami Koldewyn, Christoph Klein e Monica Biscaldi. "Adaptation to Vocal Expressions and Phonemes Is Intact in Autism Spectrum Disorder". Clinical Psychological Science 6, n. 3 (23 marzo 2018): 372–81. http://dx.doi.org/10.1177/2167702617748401.
Testo completoAbstract (sommario):
Several recent studies have demonstrated reduced visual aftereffects, particularly to social stimuli, in autism spectrum disorder (ASD). This putative impairment of the adaptive mechanism in ASD has been put forward as a possible explanation for some of the core social problems experienced by children with ASD (e.g., facial emotion or identity recognition). We addressed this claim in children with ASD and typically developing children by using an established methodology and morphed auditory stimulus set for eliciting robust aftereffects to vocal expressions and phonemes. Although children with ASD were significantly worse at categorizing the vocal expressions compared with the control stimuli (phoneme categorization), aftereffect sizes in both tasks were identical in the two participant groups. Our finding suggests that the adaptation mechanism is not universally impaired in ASD and is therefore not an explanation for the social perception difficulties in ASD.
17
Wilcox, Laurie M., Brian Timney e Michele Girash. "On the Contribution of a Binocular ‘AND’ Channel at Contrast Threshold". Perception 23, n. 6 (giugno 1994): 659–69. http://dx.doi.org/10.1068/p230659.
Testo completoAbstract (sommario):
Three experiments are reported in which an attempt was made to isolate the contribution of an AND channel by measuring aftereffects following alternating monocular adaptation. The first two were designed to test Wolf and Held's proposal that the binocular AND channel does not respond at contrast threshold. In the first experiment the relative sizes of monocular and binocular contrast threshold elevation were compared with the pattern of aftereffects obtained in a study of the suprathreshold tilt aftereffect. Identical patterns of results were obtained under the two adaptation conditions. In the second experiment, the monocular and binocular contrast-reduction aftereffect reported by Blakemore et al was measured over a wide range of reference contrasts. As in the previous experiment, the monocular effect was greater than the binocular effect. This occurred at all reference contrasts. These data support the conclusion that the AND channel contributes to visual performance in the same manner, irrespective of stimulus contrast. In the final experiment an alternative explanation for existing evidence against the existence of an AND channel was assessed.
18
Verstraten, Frans A. J., Maarten J. van der Smagt e Wim A. van de Grind. "Aftereffect of High-Speed Motion". Perception 27, n. 9 (settembre 1998): 1055–66. http://dx.doi.org/10.1068/p271055.
Testo completoAbstract (sommario):
A visual illusion known as the motion aftereffect is considered to be the perceptual manifestation of motion sensors that are recovering from adaptation. This aftereffect can be obtained for a specific range of adaptation speeds with its magnitude generally peaking for speeds around 3 deg s−1. The classic motion aftereffect is usually measured with a static test pattern. Here, we measured the magnitude of the motion aftereffect for a large range of velocities covering also higher speeds, using both static and dynamic test patterns. The results suggest that at least two (sub)populations of motion-sensitive neurons underlie these motion aftereffects. One population shows itself under static test conditions and is dominant for low adaptation speeds, and the other is prevalent under dynamic test conditions after adaptation to high speeds. The dynamic motion aftereffect can be perceived for adaptation speeds up to three times as fast as the static motion aftereffect. We tested predictions that follow from the hypothesised division in neuronal substrates. We found that for exactly the same adaptation conditions (oppositely directed transparent motion with different speeds), the aftereffect direction differs by 180° depending on the test pattern. The motion aftereffect is opposite to the pattern moving at low speed when the test pattern is static, and opposite to the high-speed pattern for a dynamic test pattern. The determining factor is the combination of adaptation speed and type of test pattern.
19
Ryan, Colin, e Barbara Gillam. "A Proximity-Contingent Stereoscopic Depth Aftereffect: Evidence for Adaptation to Disparity Gradients". Perception 22, n. 4 (aprile 1993): 403–18. http://dx.doi.org/10.1068/p220403.
Testo completoAbstract (sommario):
Prolonged inspection of a surface slanted in the third dimension of visual space typically results in a negative aftereffect such that, after adaptation, a surface in the fronto-parallel plane will appear slanted in the opposite direction. Binocular disparity is not necessary to generate such effects, since they can be obtained monocularly, presumably via adaptation to texture gradient. Six experiments demonstrated durable stereoscopic depth aftereffects in the absence of a texture gradient—by using discrete disparate objects rather than slanted surfaces— and demonstrated that adaptation was to the interobject disparity gradient rather than to the relative disparity of the objects per se. The disparity required to null the obtained aftereffects was inversely proportional to the horizontal separation of elements, for a constant disparity, and directly proportional to the separation of subsequently presented probes. When elements differed in depth (disparity), but were not laterally separated, nulling disparity was significant but invariant with changes in the horizontal separation of probe elements. In that case, adaptation was (i) either to the disparity gradient generated by the vertical separation of probe elements (of which the relative disparity component was tapped); or (ii) to relative disparity per se.
20
DeSimone, Kevin, Minjung Kim e Richard F. Murray. "Number Adaptation Can Be Dissociated From Density Adaptation". Psychological Science 31, n. 11 (20 ottobre 2020): 1470–74. http://dx.doi.org/10.1177/0956797620956986.
Testo completoAbstract (sommario):
Rapidly judging the number of objects in a scene is an important perceptual ability. Recent debates have centered on whether number perception is accomplished by dedicated mechanisms and, in particular, on whether number-adaptation aftereffects reflect adaptation of number per se or adaptation of related stimulus properties, such as density. Here, we report an adaptation experiment ( N = 8) for which the predictions of number and density theories are diametrically opposed. We found that when a reference stimulus has higher density than an adaptation stimulus but contains fewer elements, adaptation reduces the perceived number of elements in the reference stimulus. This is consistent with number adaptation and inconsistent with density adaptation. Thus, number-adaptation aftereffects are more than a by-product of density adaptation: When density and number are dissociated, adaptation effects are in the direction predicted by adaptation to number, not density.
21
Sakaguchi, Yutaka, Yu-ichi Akashi e Mitsuo Takano. "Visuo-Motor Adaptation to Stepwise and Gradual Changes in the Environment: Relationship between Consciousness and Adaptation". Journal of Robotics and Mechatronics 13, n. 6 (20 dicembre 2001): 601–13. http://dx.doi.org/10.20965/jrm.2001.p0601.
Testo completoAbstract (sommario):
Visuo-motor transformation in the human brain continuously adapts to the external environment, regardless of whether we are aware of the environmental change. This study examines the features of visuo-motor adaptation with stepwise and gradual visual shifts to explore the relationship between consciousness and adaptation. First, we ran psychological experiments, in which the amount of aftereffect was compared between the two kinds of visual shift. For most participants, almost complete aftereffects were observed in the gradual condition, while a slight aftereffect was observed in the stepwise condition. Interestingly, however, the magnitude of the aftereffect depended more on whether the participant noticed the visual shift than on whether the visual shift was stepwise or gradual. This suggests that participant consciousness is an essential factor in visuo-motor adaptation. Next, we built a computational model to simulate the experimental results. Its fundamental concepts were ""reinforcement learning"", giving a basic strategy for r choosing an appropriate motor command; ""modular architecture"", providing different visuo-motor transformations for different environments; and ""reliability of the internal model"", realizing an adaptive command selection according to the progress in learning. The behavior of the proposed model was examined in numerical experiments. Some related problems are discussed in relation to the results of psychological and numerical experiments.
22
Saul, A. B., e M. S. Cynader. "Adaptation in single units in visual cortex: The tuning of aftereffects in the spatial domain". Visual Neuroscience 2, n. 6 (giugno 1989): 593–607. http://dx.doi.org/10.1017/s0952523800003527.
Testo completoAbstract (sommario):
AbstractCat striate cortical neurons were investigated using a new method of studying adaptation aftereffects. Stimuli were sinusoidal gratings of variable contrast, spatial frequency, and drift direction and rate. A series of alternating adapting and test trials was presented while recording from single units. Control trials were completely integrated with the adapted trials in these experiments.Every cortical cell tested showed selective adaptation aftereffects. Adapting at suprathreshold contrasts invariably reduced contrast sensitivity. Significant aftereffects could be observed even when adapting at low contrasts.The spatial-frequency tuning of aftereffects varied from cell to cell. Adapting at a given spatial frequency generally resulted in a broad response reduction at test frequencies above and below the adapting frequency. Many cells lost responses predominantly at frequencies lower than the adapting frequency.The tuning of aftereffects varied with the adapting frequency. In particular, the strongest aftereffects occurred near the adapting frequency. Adapting at frequencies just above the optimum for a cell often altered the spatial-frequency tuning by shifting the peak toward lower frequencies. The fact that the tuning of aftereffects did not simply match the tuning of the cell, but depended on the adapting stimulus, implies that extrinsic mechanisms are involved in adaptation effects.
23
Menghini, Federica, Nicola van Rijsbergen e Alessandro Treves. "Modelling adaptation aftereffects in associative memory". Neurocomputing 70, n. 10-12 (giugno 2007): 2000–2004. http://dx.doi.org/10.1016/j.neucom.2006.10.081.
Testo completo
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McKone, E., M. Edwards, R. Robbins e R. Anderson. "The stickiness of face adaptation aftereffects". Journal of Vision 5, n. 8 (1 settembre 2005): 822. http://dx.doi.org/10.1167/5.8.822.
Testo completo
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Vasudevan, Erin V. L., e Amy J. Bastian. "Split-Belt Treadmill Adaptation Shows Different Functional Networks for Fast and Slow Human Walking". Journal of Neurophysiology 103, n. 1 (gennaio 2010): 183–91. http://dx.doi.org/10.1152/jn.00501.2009.
Testo completoAbstract (sommario):
New walking patterns can be learned over short time scales (i.e., adapted in minutes) using a split-belt treadmill that controls the speed of each leg independently. This leads to storage of a modified motor pattern that is expressed as an aftereffect in regular walking conditions and must be de-adapted to return to normal. Here we asked whether the nervous system adapts a general walking pattern that is used across many speeds or a specific pattern affecting only the two speeds experienced during split-belt training. In experiment 1, we tested three groups of healthy adult subjects walking at different split-belt speed combinations and then assessed aftereffects at a range of speeds. We found that aftereffects were largest at the slower speed that was used in split-belt training in all three groups, and it decayed gradually for all other speeds. Thus adaptation appeared to be more strongly linked to the slow walking speed. This result suggests a separation in the functional networks used for fast and slow walking. We tested this in experiment 2 by adapting walking to split belts and then determining how much fast regular walking washed out the slow aftereffect and vice versa. We found that 23–38% of the aftereffect remained regardless of which speed was washed out first. This demonstrates that there is only partial overlap in the functional networks coordinating different walking speeds. Taken together, our results suggest that there are some neural networks for controlling locomotion that are recruited specifically for fast versus slow walking in humans, similar to recent findings in other vertebrates.
26
Wei, Wei, Teng Leng Ooi e Zijiang J. He. "Aftereffects of apparent motion adaptation depends on adaptation duration". Journal of Vision 19, n. 10 (6 settembre 2019): 286c. http://dx.doi.org/10.1167/19.10.286c.
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Saul, A. B., e M. S. Cynader. "Adaptation in single units in visual cortex: The tuning of aftereffects in the temporal domain". Visual Neuroscience 2, n. 6 (giugno 1989): 609–20. http://dx.doi.org/10.1017/s0952523800003539.
Testo completoAbstract (sommario):
AbstractAdaptation-induced changes in the temporal-frequency tuning and direction selectivity of cat visual cortical cells were studied. Aftereffects were induced largely independent of direction. Adapting in either direction reduced responses in both directions. Aftereffects in the direction opposite that adapted were only slightly weaker than were aftereffects in the adapted direction. No cell showed any enhancement of responses to drifting test stimuli after adapting with moving gratings. Adapting in a cell's null direction usually had no effect. Dramatic differences between the adaptation characteristics of moving and stationary stimuli were observed, however.Furthermore, aftereffects were temporal frequency specific. Temporal frequency-specific aftereffects were found in both directions: adapting in one direction induced frequency-specific effects in both directions. This bidirectionality of frequency-specific aftereffects applied to the spatial domain as well. Often, aftereffects in the direction opposite that adapted were more narrowly tuned.In general, adaptation could shift a cell's preferred temporal frequency. Aftereffects were most prominent at high temporal frequencies when testing in the adapted direction. Aftereffects seemed to be more closely linked to temporal frequency than to velocity matching.These results constrain models of cortical connectivity. In particular, we argue against schemes by which direction selectivity is generated by inhibiting a cell specifically when stimulated in the nonpreferred direction. Instead, we argue that cells receive bidirectional spatially and temporally tuned inputs, which could combine in spatiotemporal quadrature to produce direction selectivity.
28
Ehrenstein, Walter H., e Anthony H. Reinhardt-Rutland. "A Cross-Modal Aftereffect: Auditory Displacement following Adaptation to Visual Motion". Perceptual and Motor Skills 82, n. 1 (febbraio 1996): 23–26. http://dx.doi.org/10.2466/pms.1996.82.1.23.
Testo completoAbstract (sommario):
It has been shown earlier that the perceived location of static sound-sources can be displaced (a) during visual motion and (b) following auditory motion. Here we combine these phenomena. The subject adapted to the horizontal visual motion of a surrounding drum, then (with the lights off) localized static sound-sources by setting the direction of a pointer. Adapting motion was clockwise or counterclockwise: the difference between each subject's settings following the opposite directions of adaptation showed small but consistent auditory displacements opposite to the adapting directions. This visual-auditory aftereffect, which is consistent with sensorineural data, challenges a general, if implicit, belief that aftereffects do not cross modalities.
29
Thompson, Peter, e Justin Wright. "The Role of Intervening Patterns in the Storage of the Movement Aftereffect". Perception 23, n. 10 (ottobre 1994): 1233–40. http://dx.doi.org/10.1068/p231233.
Testo completoAbstract (sommario):
Wohlgemuth, having measured the duration of the motion aftereffect (MAE), instructed subjects to close their eyes immediately after adaptation for a period of time longer than the MAE. Upon opening their eyes the subjects reported a residual effect, albeit somewhat shorter than the original effect. Thus the decay of the aftereffect appeared to have been retarded by the period of darkness. This effect is known as ‘storage’ and poses a problem for any model of the MAE based on the fatiguing of direction-selective units in the visual pathway. A reexamination is made of storage of the MAE, again concentrating on the intervening stimulation between movement adaptation and aftereffect test. The results suggest that the nature of the intervening pattern between adaptation and test conditions is remarkably unimportant. A total of 11 different storage patterns were examined after adaptation to high-contrast drifting horizontal sinewave gratings. For 10 of these patterns large and robust storage effects were found. The exception occurred when the spatial pattern of the storage stimulus was identical to the adaptation and test stimuli. It is proposed that storage cannot be understood in terms of a simple fatigue model of the MAE and that one component of the effect may share similarities with contingent aftereffects.
30
Houldin, Adina, Romeo Chua, Mark G. Carpenter e Tania Lam. "Limited interlimb transfer of locomotor adaptations to a velocity-dependent force field during unipedal walking". Journal of Neurophysiology 108, n. 3 (1 agosto 2012): 943–52. http://dx.doi.org/10.1152/jn.00670.2011.
Testo completoAbstract (sommario):
Several studies have demonstrated that motor adaptations to a novel task environment can be transferred between limbs. Such interlimb transfer of motor commands is consistent with the notion of centrally driven strategies that can be generalized across different frames of reference. So far, studies of interlimb transfer of locomotor adaptations have yielded disparate results. Here we sought to determine whether locomotor adaptations in one (trained) leg show transfer to the other (test) leg during a unipedal walking task. We hypothesized that adaptation in the test leg to a velocity-dependent force field previously experienced by the trained leg will be faster, as revealed by faster recovery of kinematic errors and earlier onset of aftereffects. Twenty able-bodied adults walked unipedally in the Lokomat robotic gait orthosis, which applied velocity-dependent resistance to the legs. The amount of resistance was scaled to 10% of each individual's maximum voluntary contraction of the hip flexors. Electromyography and kinematics of the lower limb were recorded. All subjects were right-leg dominant and were tested for transfer of motor adaptations from the right leg to the left leg. Catch trials, consisting of unexpected removal of resistance, were presented after the first step with resistance and after a period of adaptation to test for aftereffects. We found no significant differences in the sizes of the aftereffects between the two legs, except for peak hip flexion during swing, or in the rate at which peak hip flexion adapted during steps against resistance between the two legs. Our results indicate that interlimb transfer of these types of locomotor adaptation is not a robust phenomenon. These findings add to our current understanding of motor adaptations and provide further evidence that generalization of adaptations may be dependent on the movement task.
31
Wade, N. J., V. Pardieu e M. T. Swanston. "Local and Global Properties of Motion Aftereffects". Perception 25, n. 1_suppl (agosto 1996): 170. http://dx.doi.org/10.1068/v96l0801.
Testo completoAbstract (sommario):
The local motion adaptation at the basis of the motion aftereffect (MAE) can be expressed in a variety of ways, depending upon the structure of the test display (N J Wade, L Spillmann, M T Swanston Vision Research in press). This has been demonstrated with MAEs from induced motion: if adaptation is to two moving (Surround) gratings, an MAE is seen in the central grating if two gratings surround it, but in the flanking gratings when they are themselves surrounded in the test stimulus. We report two experiments in which the characteristics of the test display and of the local adaptation process have been examined. In experiment 1, five vertical gratings were presented during adaptation; the outermost and central gratings remained stationary and those flanking the centre moved laterally. The test display always consisted of three stationary gratings: either the central three or the lower three equivalent to the locations of the adaptation display. MAEs were only recorded in the Centre and not in the Surround, irrespective of whether the Centre or Surround had been exposed to motion during adaptation. MAEs in the Centre were in opposite directions, reflecting the influence of Surround adaptation. The influence of adapting motion in different directions was examined in experiment 2. The upper grating always received the same direction of motion during adaptation, and the lower grating was absent, stationary, or moving in the same or in the opposite direction. The results indicate that an MAE is visible in the upper grating only after differential adaptation between the upper and lower gratings.
32
Cziraki, Csaba, Mark W. Greenlee e Gyula Kovács. "Neural Correlates of High-Level Adaptation-Related Aftereffects". Journal of Neurophysiology 103, n. 3 (marzo 2010): 1410–17. http://dx.doi.org/10.1152/jn.00582.2009.
Testo completoAbstract (sommario):
Prolonged exposure to complex stimuli, such as faces, biases perceptual decisions toward nonadapted, dissimilar stimuli, leading to contrastive aftereffects. Here we tested the neural correlates of this perceptual bias using a functional magnetic resonance imaging adaptation (fMRIa) paradigm. Adaptation to a face or hand stimulus led to aftereffects by biasing the categorization of subsequent ambiguous face/hand composite stimuli away from the adaptor category. The simultaneously observed fMRIa in the face-sensitive fusiform face area (FFA) and in the body-part–sensitive extrastriate body area (EBA) depended on the behavioral response of the subjects: adaptation to the preferred stimulus of the given area led to larger signal reduction during trials when it biased perception than during trials when it was less effective. Activity in two frontal areas correlated positively with the activity patterns in FFA and EBA. Based on our novel adaptation paradigm, the results suggest that the adaptation-induced aftereffects are mediated by the relative activity of category-sensitive areas of the human brain as demonstrated by fMRI.
33
Kaiser, Daniel, Christian Walther, Stefan R. Schweinberger e Gyula Kovács. "Dissociating the neural bases of repetition-priming and adaptation in the human brain for faces". Journal of Neurophysiology 110, n. 12 (15 dicembre 2013): 2727–38. http://dx.doi.org/10.1152/jn.00277.2013.
Testo completoAbstract (sommario):
The repetition of a given stimulus leads to the attenuation of the functional magnetic resonance imaging (fMRI) signal compared with unrepeated stimuli, a phenomenon called fMRI adaptation or repetition suppression (RS). Previous studies have related RS of the fMRI signal behaviorally both to improved performance for the repeated stimulus (priming) and to shifts of perception away from the first stimulus (adaptation-related aftereffects). Here we used identical task (sex discrimination), trial structure [ stimulus 1 (S1): 3,000 ms, interstimulus interval: 600 ms, stimulus 2 (S2): 300 ms], and S2 stimuli (androgynous faces) to test how RS of the face-specific areas of the occipito-temporal cortex relates to priming and aftereffects. By varying S1, we could induce priming (significantly faster reaction times when S1 and S2 were identical compared with different images) as well as sex-specific aftereffect [an increased ratio of male responses if S1 was a female face compared with ambiguous faces or to Fourier-randomized noise (FOU) images]. Presenting any face as S1 led to significant RS of the blood oxygen level-dependent signal in the fusiform and occipital face areas as well as in the lateral occipital cortex of both hemispheres compared with FOU, reflecting stimulus category-specific encoding. Additionally, while sex-specific adaptation effects were only observed in occipital face areas, primed trials led to a signal reduction in both face-selective regions. Altogether, these results suggest the differential neural mechanisms of adaptation and repetition priming.
34
ZHANG, Zhijun, Wei LIU, Yajun ZHAO, Jingshu ZHANG e Binxing WU. "Cortical Remapping Features of Numerosity Adaptation Aftereffects". Acta Psychologica Sinica 46, n. 1 (2014): 5. http://dx.doi.org/10.3724/sp.j.1041.2014.00005.
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35
Emery, Kara. "Inferring neural coding strategies from adaptation aftereffects". Journal of Vision 19, n. 10 (6 settembre 2019): 6d. http://dx.doi.org/10.1167/19.10.6d.
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36
Zimmer, Márta, e Gyula Kovács. "Position specificity of adaptation-related face aftereffects". Philosophical Transactions of the Royal Society B: Biological Sciences 366, n. 1564 (27 febbraio 2011): 586–95. http://dx.doi.org/10.1098/rstb.2010.0265.
Testo completoAbstract (sommario):
It has been shown that prolonged exposure to a human face leads to shape-selective visual aftereffects. It seems that these face-specific aftereffects (FAEs) have multiple components, related to the adaptation of earlier and higher level processing of visual stimuli. The largest magnitude of FAE, using long-term adaptation periods, is usually observed at the retinotopic position of the preceding adaptor stimulus. However, FAE is also detected, to a smaller degree, at other retinal positions in a spatially invariant way and this component depends less on the adaptation duration. Several lines of evidences suggest that while the position-specific FAE involves lower level areas of the ventral processing stream, the position-invariant FAE depends on the activation of higher level face-processing areas and the fusiform gyrus in particular. In the present paper, we summarize the available behavioural, electrophysiological and neuroimaging results regarding the spatial selectivity of FAE and discuss their implications for the visual stability of object representations across saccadic eye movements.
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Takahashi, Nozomi, Chang Hong Liu e Hiroshi Yamada. "Adaptation Aftereffects May Decipher Ophelia's Facial Expression". Perception 43, n. 12 (dicembre 2014): 1393–99. http://dx.doi.org/10.1068/p7838.
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Zäske, Romi, Stefan R. Schweinberger e Hideki Kawahara. "Voice aftereffects of adaptation to speaker identity". Hearing Research 268, n. 1-2 (settembre 2010): 38–45. http://dx.doi.org/10.1016/j.heares.2010.04.011.
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39
Kabbaligere, Rakshatha, e Charles S. Layne. "Adaptation in Gait to Body-Weight Unloading". Applied Sciences 9, n. 21 (23 ottobre 2019): 4494. http://dx.doi.org/10.3390/app9214494.
Testo completoAbstract (sommario):
Modifications in load-related sensory input during unloaded walking can lead to recalibration of the body schema and result in aftereffects. The main objective of this study was to identify the adaptive changes in gait and body-weight perception produced by unloaded walking. Gait performance during treadmill walking was assessed in 12 young participants before and after 30 min of unloaded walking (38% body weight) by measuring lower limb kinematics, temporal gait measures, and electromyography (EMG). A customized weight-perception scale was used to assess perception of body weight. Participants perceived their body weight to be significantly heavier than normal after unloading while walking. Angular displacement about ankle and knee was significantly reduced immediately after unloaded walking, while temporal gait parameters remained unchanged. The EMG activity in some muscles was significantly reduced after unloading. These findings indicate that walking at reduced body weight results in alterations in segmental kinematics, neuromuscular activity, and perception of body weight, which are the aftereffects of motor adaptation to altered load-related afferent information produced by unloading. Understanding the adaptive responses of gait to unloading and the time course of the aftereffects will be useful for practitioners who use body-weight unloading for rehabilitation.
40
Morton, Susanne M., e Amy J. Bastian. "Prism Adaptation During Walking Generalizes to Reaching and Requires the Cerebellum". Journal of Neurophysiology 92, n. 4 (ottobre 2004): 2497–509. http://dx.doi.org/10.1152/jn.00129.2004.
Testo completoAbstract (sommario):
Adaptation of arm movements to laterally displacing prism glasses is usually highly specific to body part and movement type and is known to require the cerebellum. Here, we show that prism adaptation of walking trajectory generalizes to reaching (a different behavior involving a different body part) and that this adaptation requires the cerebellum. In experiment 1, healthy control subjects adapted to prisms during either reaching or walking and were tested for generalization to the other movement type. We recorded lateral deviations in finger endpoint position and walking direction to measure negative aftereffects and generalization. Results showed that generalization of prism adaptation is asymmetric: walking generalizes extensively to reaching, but reaching does not generalize to walking. In experiment 2, we compared the performance of cerebellar subjects versus healthy controls during the prism walking adaptation. We measured rates of adaptation, aftereffects, and generalization. Cerebellar subjects had reduced adaptation magnitudes, slowed adaptation rates, decreased negative aftereffects, and poor generalization. Based on these experiments, we propose that prism adaptation during whole body movements through space invokes a more general system for visuomotor remapping, involving recalibration of higher-order, effector-independent brain regions. In contrast, prism adaptation during isolated movements of the limbs is probably recalibrated by effector-specific mechanisms. The cerebellum is an essential component in the network for both types of prism adaptation.
41
Kristjánsson, Árni. "The Functional Benefits of Tilt Adaptation". Seeing and Perceiving 24, n. 1 (2011): 37–51. http://dx.doi.org/10.1163/187847511x555283.
Testo completoAbstract (sommario):
AbstractMany have argued that effects of adaptation, such as aftereffects from motion or tilt, reflect that the visual system hones its responses in on the characteristics of the adapting stimulus. This view entails that on average, the discrimination of the characteristics of an adapting stimulus should become easier as viewing time increases since the variation in the response gradually adapts to the range and variation in the stimulus. Here this was tested for adaptation to tilt. Observers viewed a Gabor patch which varied in contrast from 0 to 74% at a rate of 0.6 Hz, for 4, 8, 16 or 32 s, after which the Gabor patch changed orientation (at the point when contrast was 0). The results show that the longer the observers adapt to the dynamic Gabor, the better they become at discriminating between clockwise (CW) or counterclockwise (CCW) changes in tilt (orientation) of the same patch. Experiment 2 confirms that both the direct and indirect tilt aftereffects are seen with this contrast varying Gabor patch and Experiment 3 shows that the aftereffects are only slightly smaller than in other studies with stimuli such as lines and sinusoidal gratings. These results show that adaptation to tilt leads to better discrimination around the orientation of the adapting stimulus itself, and that discrimination performance improves steadily with increased adaptation time. The results support proposals that the visual system adjusts its response characteristics to the properties of the visual input at a given time.
42
Mack, Arien, James Hill e Steven Kahn. "Motion Aftereffects and Retinal Motion". Perception 18, n. 5 (ottobre 1989): 649–55. http://dx.doi.org/10.1068/p180649.
Testo completoAbstract (sommario):
Two experiments are described in which it was investigated whether the adaptation on which motion aftereffects (MAEs) are based is a response to retinal image motion alone or to the motion signal derived from the process which combines the image motion signal with information about eye movement (corollary discharge). In both experiments observers either fixated a stationary point or tracked a vertically moving point while a pattern (in experiment 1, a grating; in experiment 2, a random-dot pattern) drifted horizontally across the field. In the tracking condition the adapting retinal motion was oblique. In the fixation condition it was horizontal. In every case in both conditions the MAE was horizontal, in the direction opposite to that of pattern motion. These results are consistent with the hypothesis that the adaptation is a response to the motion signal derived from the comparison of eye and image motion rather than to retinal motion per se. An alternative explanation is discussed.
43
Reisman, Darcy S., Robert Wityk, Kenneth Silver e Amy J. Bastian. "Split-Belt Treadmill Adaptation Transfers to Overground Walking in Persons Poststroke". Neurorehabilitation and Neural Repair 23, n. 7 (23 marzo 2009): 735–44. http://dx.doi.org/10.1177/1545968309332880.
Testo completoAbstract (sommario):
Background and Objective. Following stroke, subjects retain the ability to adapt interlimb symmetry on the split-belt treadmill. Critical to advancing our understanding of locomotor adaptation and its usefulness in rehabilitation is discerning whether adaptive effects observed on a treadmill transfer to walking over ground. We examined whether aftereffects following split-belt treadmill adaptation transfer to overground walking in healthy persons and those poststroke. Methods. Eleven poststroke and 11 age-matched and gender-matched healthy subjects walked over ground before and after walking on a split-belt treadmill. Adaptation and aftereffects in step length and double support time were calculated. Results. Both groups demonstrated partial transfer of the aftereffects observed on the treadmill ( P < .001) to overground walking ( P < .05), but the transfer was more robust in the subjects poststroke ( P < .05). The subjects with baseline asymmetry after stroke improved in asymmetry of step length and double limb support ( P = .06). Conclusions. The partial transfer of aftereffects to overground walking suggests that some shared neural circuits that control locomotion for different environmental contexts are adapted during split-belt treadmill walking. The larger adaptation transfer from the treadmill to overground walking in the stroke survivors may be due to difficulty adjusting their walking pattern to changing environmental demands. Such difficulties with context switching have been considered detrimental to function poststroke. However, we propose that the persistence of improved symmetry when changing context to overground walking could be used to advantage in poststroke rehabilitation.
44
Simani, M. C., L. M. M. McGuire e P. N. Sabes. "Visual-Shift Adaptation Is Composed of Separable Sensory and Task-Dependent Effects". Journal of Neurophysiology 98, n. 5 (novembre 2007): 2827–41. http://dx.doi.org/10.1152/jn.00290.2007.
Testo completoAbstract (sommario):
Visuomotor coordination requires both the accurate alignment of spatial information from different sensory streams and the ability to convert these sensory signals into accurate motor commands. Both of these processes are highly plastic, as illustrated by the rapid adaptation of goal-directed movements following exposure to shifted visual feedback. Although visual-shift adaptation is a widely used model of sensorimotor learning, the multifaceted adaptive response is typically poorly quantified. We present an approach to quantitatively characterizing both sensory and task-dependent components of adaptation. Sensory aftereffects are quantified with “alignment tests” that provide a localized, two-dimensional measure of sensory recalibration. These sensory effects obey a precise form of “additivity,” in which the shift in sensory alignment between vision and the right hand is equal to the vector sum of the shifts between vision and the left hand and between the right and left hands. This additivity holds at the exposure location and at a second generalization location. These results support a component transformation model of sensory coordination, in which eye–hand and hand–hand alignment relies on a sequence of shared sensory transformations. We also ask how these sensory effects compare with the aftereffects measured in target reaching and tracking tasks. We find that the aftereffect depends on both the task performed during feedback-shift exposure and on the testing task. The results suggest the presence of both a general sensory recalibration and task-dependent sensorimotor effect. The task-dependent effect is observed in highly stereotyped reaching movements, but not in the more variable tracking task.
45
Tao, Ran, Martin J. M. Lankheet, Wim A. van de Grind e Richard J. A. van Wezel. "Velocity Dependence of the Interocular Transfer of Dynamic Motion Aftereffects". Perception 32, n. 7 (luglio 2003): 855–66. http://dx.doi.org/10.1068/p3442.
Testo completoAbstract (sommario):
It is well established that motion aftereffects (MAEs) can show interocular transfer (IOT); that is, motion adaptation in one eye can give a MAE in the other eye. Different quantification methods and different test stimuli have been shown to give different IOT magnitudes, varying from no to almost full IOT. In this study, we examine to what extent IOT of the dynamic MAE (dMAE), that is the MAE seen with a dynamic noise test pattern, varies with velocity of the adaptation stimulus. We measured strength of dMAE by a nulling method. The aftereffect induced by adaptation to a moving random-pixel array was compensated (nulled), during a brief dynamic test period, by the same kind of motion stimulus of variable luminance signal-to-noise ratio (LSNR). The LSNR nulling value was determined in a Quest-staircase procedure. We found that velocity has a strong effect on the magnitude of IOT for the dMAE. For increasing speeds from 1.5 deg s−1 to 24 deg s−1 average IOT values increased about linearly from 18% to 63% or from 32% to 83%, depending on IOT definition. The finding that dMAEs transfer to an increasing extent as speed increases, suggests that binocular cells play a more dominant role at higher speeds.
46
Wade, Nicholas J., Michael T. Swanston e Charles M. M. de Weert. "On Interocular Transfer of Motion Aftereffects". Perception 22, n. 11 (novembre 1993): 1365–80. http://dx.doi.org/10.1068/p221365.
Testo completoAbstract (sommario):
A brief history of quantitative assessments of interocular transfer (IOT) of the motion aftereffect (MAE) is presented. Recent research indicates that the MAE occurs as a consequence of adapting detectors for relative rather than retinal motion. When gratings above and below a stationary, fixated grating are moved in an otherwise dark field the central, retinally stationary grating appears to move in the opposite direction; when tested with stationary gratings an MAE is almost entirely confined to the central grating. The IOT of such an MAE was measured in experiment 1: the display was presented to one eye with a black field in the other. The IOT was about 30% of the monocular MAE. Similar values were found in experiment 2, in which the contralateral eye received an equivalent central stationary grating during adaptation and test. The dichoptic interaction of the processes involved in the MAE was examined by presenting the central gratings to both eyes and a single flanking grating above in one eye and below in the other (experiment 3). The MAE was tested with either the same or the contralateral pairing. Oppositely directed MAEs were found for the central and flanking gratings, but they were confined mainly to the conditions in which the configurations presented during adaptation were present in the same eyes during test. In experiment 4, the surround MAEs were compared after adaptation with two moving gratings in one eye or with a similar dichoptic configuration, and they were of similar duration. In a final experiment the MAE was tested either monocularly or binocularly after alternating adaptation of the left and right eyes and was found to be of the same duration. It is concluded that the MAE is a consequence of adapting relational-motion detectors, which are either monocular or of the binocular OR class.
47
Wade, Nicholas J., e Véronique Salvano-Pardieu. "Visual motion aftereffects: Differential adaptation and test stimulation". Vision Research 38, n. 4 (febbraio 1998): 573–78. http://dx.doi.org/10.1016/s0042-6989(97)00196-x.
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Jeffery, L., S. Petrovski e G. Rhodes. "Adaptation to Dynamic Faces Produces Face Identity Aftereffects". Journal of Vision 14, n. 10 (22 agosto 2014): 554. http://dx.doi.org/10.1167/14.10.554.
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Swe, Derek C., Nichola S. Burton e Gillian Rhodes. "Are expression aftereffects fully explained by tilt adaptation?" Journal of Vision 19, n. 14 (23 dicembre 2019): 21. http://dx.doi.org/10.1167/19.14.21.
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Swe, Derek, Nichola Burton e Gillian Rhodes. "Can expression aftereffects be explained by tilt adaptation?" Journal of Vision 19, n. 8 (2 luglio 2019): 79. http://dx.doi.org/10.1167/19.8.79.
Testo completo