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1
Pesavento, Michael J., Cynthia D. Rittenhouse, and David J. Pinto. "Response Sensitivity of Barrel Neuron Subpopulations to Simulated Thalamic Input." Journal of Neurophysiology 103, no. 6 (June 2010): 3001–16. http://dx.doi.org/10.1152/jn.01053.2009.
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Our goal is to examine the relationship between neuron- and network-level processing in the context of a well-studied cortical function, the processing of thalamic input by whisker-barrel circuits in rodent neocortex. Here we focus on neuron-level processing and investigate the responses of excitatory and inhibitory barrel neurons to simulated thalamic inputs applied using the dynamic clamp method in brain slices. Simulated inputs are modeled after real thalamic inputs recorded in vivo in response to brief whisker deflections. Our results suggest that inhibitory neurons require more input to reach firing threshold, but then fire earlier, with less variability, and respond to a broader range of inputs than do excitatory neurons. Differences in the responses of barrel neuron subtypes depend on their intrinsic membrane properties. Neurons with a low input resistance require more input to reach threshold but then fire earlier than neurons with a higher input resistance, regardless of the neuron's classification. Our results also suggest that the response properties of excitatory versus inhibitory barrel neurons are consistent with the response sensitivities of the ensemble barrel network. The short response latency of inhibitory neurons may serve to suppress ensemble barrel responses to asynchronous thalamic input. Correspondingly, whereas neurons acting as part of the barrel circuit in vivo are highly selective for temporally correlated thalamic input, excitatory barrel neurons acting alone in vitro are less so. These data suggest that network-level processing of thalamic input in barrel cortex depends on neuron-level processing of the same input by excitatory and inhibitory barrel neurons.
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Weissenberger, Felix, Marcelo Matheus Gauy, Xun Zou, and Angelika Steger. "Mutual Inhibition with Few Inhibitory Cells via Nonlinear Inhibitory Synaptic Interaction." Neural Computation 31, no. 11 (November 2019): 2252–65. http://dx.doi.org/10.1162/neco_a_01230.
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In computational neural network models, neurons are usually allowed to excite some and inhibit other neurons, depending on the weight of their synaptic connections. The traditional way to transform such networks into networks that obey Dale's law (i.e., a neuron can either excite or inhibit) is to accompany each excitatory neuron with an inhibitory one through which inhibitory signals are mediated. However, this requires an equal number of excitatory and inhibitory neurons, whereas a realistic number of inhibitory neurons is much smaller. In this letter, we propose a model of nonlinear interaction of inhibitory synapses on dendritic compartments of excitatory neurons that allows the excitatory neurons to mediate inhibitory signals through a subset of the inhibitory population. With this construction, the number of required inhibitory neurons can be reduced tremendously.
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Nykamp, Duane Q., and Daniel Tranchina. "A Population Density Approach That Facilitates Large-Scale Modeling of Neural Networks: Extension to Slow Inhibitory Synapses." Neural Computation 13, no. 3 (March 1, 2001): 511–46. http://dx.doi.org/10.1162/089976601300014448.
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A previously developed method for efficiently simulating complex networks of integrate-and-fire neurons was specialized to the case in which the neurons have fast unitary postsynaptic conductances. However, inhibitory synaptic conductances are often slower than excitatory ones for cortical neurons, and this difference can have a profound effect on network dynamics that cannot be captured with neurons that have only fast synapses. We thus extend the model to include slow inhibitory synapses. In this model, neurons are grouped into large populations of similar neurons. For each population, we calculate the evolution of a probability density function (PDF), which describes the distribution of neurons over state-space. The population firing rate is given by the flux of probability across the threshold voltage for firing an action potential. In the case of fast synaptic conductances, the PDF was one-dimensional, as the state of a neuron was completely determined by its transmembrane voltage. An exact extension to slow inhibitory synapses increases the dimension of the PDF to two or three, as the state of a neuron now includes the state of its inhibitory synaptic conductance. However, by assuming that the expected value of a neuron's inhibitory conductance is independent of its voltage, we derive a reduction to a one-dimensional PDF and avoid increasing the computational complexity of the problem. We demonstrate that although this assumption is not strictly valid, the results of the reduced model are surprisingly accurate.
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Hu, Xiaolin, and Zhigang Zeng. "Bridging the Functional and Wiring Properties of V1 Neurons Through Sparse Coding." Neural Computation 34, no. 1 (January 1, 2022): 104–37. http://dx.doi.org/10.1162/neco_a_01453.
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Abstract The functional properties of neurons in the primary visual cortex (V1) are thought to be closely related to the structural properties of this network, but the specific relationships remain unclear. Previous theoretical studies have suggested that sparse coding, an energy-efficient coding method, might underlie the orientation selectivity of V1 neurons. We thus aimed to delineate how the neurons are wired to produce this feature. We constructed a model and endowed it with a simple Hebbian learning rule to encode images of natural scenes. The excitatory neurons fired sparsely in response to images and developed strong orientation selectivity. After learning, the connectivity between excitatory neuron pairs, inhibitory neuron pairs, and excitatory-inhibitory neuron pairs depended on firing pattern and receptive field similarity between the neurons. The receptive fields (RFs) of excitatory neurons and inhibitory neurons were well predicted by the RFs of presynaptic excitatory neurons and inhibitory neurons, respectively. The excitatory neurons formed a small-world network, in which certain local connection patterns were significantly overrepresented. Bidirectionally manipulating the firing rates of inhibitory neurons caused linear transformations of the firing rates of excitatory neurons, and vice versa. These wiring properties and modulatory effects were congruent with a wide variety of data measured in V1, suggesting that the sparse coding principle might underlie both the functional and wiring properties of V1 neurons.
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Liu, Ming-Zhe, Xiao-Jun Chen, Tong-Yu Liang, Qing Li, Meng Wang, Xin-Yan Zhang, Yu-Zhuo Li, Qiang Sun, and Yan-Gang Sun. "Synaptic control of spinal GRPR+neurons by local and long-range inhibitory inputs." Proceedings of the National Academy of Sciences 116, no. 52 (December 5, 2019): 27011–17. http://dx.doi.org/10.1073/pnas.1905658116.
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Spinal gastrin-releasing peptide receptor-expressing (GRPR+) neurons play an essential role in itch signal processing. However, the circuit mechanisms underlying the modulation of spinal GRPR+neurons by direct local and long-range inhibitory inputs remain elusive. Using viral tracing and electrophysiological approaches, we dissected the neural circuits underlying the inhibitory control of spinal GRPR+neurons. We found that spinal galanin+GABAergic neurons form inhibitory synapses with GRPR+neurons in the spinal cord and play an important role in gating the GRPR+neuron-dependent itch signaling pathway. Spinal GRPR+neurons also receive inhibitory inputs from local neurons expressing neuronal nitric oxide synthase (nNOS). Moreover, spinal GRPR+neurons are gated by strong inhibitory inputs from the rostral ventromedial medulla. Thus, both local and long-range inhibitory inputs could play important roles in gating itch processing in the spinal cord by directly modulating the activity of spinal GRPR+neurons.
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Tamura, Hiroshi, Hidekazu Kaneko, Keisuke Kawasaki, and Ichiro Fujita. "Presumed Inhibitory Neurons in the Macaque Inferior Temporal Cortex: Visual Response Properties and Functional Interactions With Adjacent Neurons." Journal of Neurophysiology 91, no. 6 (June 2004): 2782–96. http://dx.doi.org/10.1152/jn.01267.2003.
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Neurons in area TE of the monkey inferior temporal cortex respond selectively to images of particular objects or their characteristic visual features. The mechanism of generation of the stimulus selectivity, however, is largely unknown. This study addresses the role of inhibitory TE neurons in this process by examining their visual response properties and interactions with adjacent target neurons. We applied cross-correlation analysis to spike trains simultaneously recorded from pairs of adjacent neurons in anesthetized macaques. Neurons whose activity preceded a decrease in activity from their partner were presumed to be inhibitory neurons. Excitatory neurons were also identified as the source neuron of excitatory linkage as evidenced by a sharp peak displaced from the 0-ms bin in cross-correlograms. Most inhibitory neurons responded to a variety of visual stimuli in our stimulus set, which consisted of several dozen geometrical figures and photographs of objects, with a clear stimulus preference. On average, 10% of the stimuli increased firing rates of the inhibitory neurons. Both excitatory and inhibitory neurons exhibited a similar degree of stimulus selectivity. Although inhibitory neurons occasionally shared the most preferred stimuli with their target neurons, overall stimulus preferences were less similar between adjacent neurons with inhibitory linkages than adjacent neurons with common inputs and/or excitatory linkages. These results suggest that inhibitory neurons in area TE are activated selectively and exert stimulus-specific inhibition on adjacent neurons, contributing to shaping of stimulus selectivity of TE neurons.
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Shosaku, A. "Cross-correlation analysis of a recurrent inhibitory circuit in the rat thalamus." Journal of Neurophysiology 55, no. 5 (May 1, 1986): 1030–43. http://dx.doi.org/10.1152/jn.1986.55.5.1030.
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Spontaneous activities of vibrissa-responding neurons in the rat ventrobasal complex (VB) and somatosensory part of the thalamic reticular nucleus (S-TR) were simultaneously recorded and subjected to cross-correlation analysis to investigate the functional organization of recurrent inhibitory action of the S-TR on VB neurons. Excitatory and/or inhibitory interactions were found between approximately 75% (25/34) of the pairs of S-TR and VB neurons with receptive fields (RFs) on the same vibrissa. In contrast, there was no significant interaction between 54 pairs of neurons having RFs on different vibrissae. Among the pairs of neurons with RFs on the same vibrissa, there were four types of correlations, which indicate the following connections: monosynaptic excitation from a VB to an S-TR neuron (7 pairs), monosynaptic inhibition from an S-TR to a VB neuron (10 pairs), reciprocal connection combining the above two types (7 pairs), and common excitation in addition to inhibition from an S-TR to a VB neuron (1 pair). Examples of divergence and convergence of connections between S-TR and VB neurons were demonstrated by testing one S-TR (VB) neuron with more than one VB (S-TR) neuron. Vibrissa-suppressed VB cells, which had exclusively inhibitory RFs, were included in eight pairs of the above samples. These VB cells were more likely to receive inhibitory inputs from S-TR neurons than other VB neurons. Cells with RFs on multiple vibrissae were included in the other 10 pairs. These multiple-vibrissa cells had no interaction with single-vibrissa cells but did with multiple-vibrissa cells. From the incidence of four types of correlation between S-TR and VB neurons with RFs on the same vibrissa, the following connection pattern is suggested: One S-TR neuron receives excitatory inputs from approximately 40% of the VB neurons with RFs on the same vibrissa and sends inhibitory outputs to approximately 55%. Since these two groups of VB neurons were overlapping, the S-TR neuron has reciprocal connections with approximately 20% of the VB neurons with RFs on the same vibrissa. The same estimate was applied to connectivity of one VB neuron. These results indicate that both inputs and outputs of S-TR neurons are precisely and topographically organized, although there is convergence to and divergence from a substantial number of VB neurons with RFs on the same vibrissa. It is proposed that the recurrent inhibitory circuit through the S-TR plays a role in improving discrimination of sensory information transmitted through the VB.
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Lu, Yun-Fei, Yykio Hattori, Akiyoshi Moriwaki, Yasushi Hayashi, and Yasuo Hori. "Inhibition of neurons in the rat medial amygdaloid nucleus in vitro by somatostatin." Canadian Journal of Physiology and Pharmacology 73, no. 5 (May 1, 1995): 670–74. http://dx.doi.org/10.1139/y95-086.
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Effects of somatostatin (SRIF) on neurons in the medial amygdaloid nucleus were investigated in rat brain slice preparations, using extracellular recordings. Following bath application of SRIF at 10−7–10−6 M, 63 of 81 (78%) medial amygdala neurons showed an inhibitory response. The inhibitory effect of SRIF was dose dependent, and the threshold concentration was approximately 10−9 M. The inhibitory response to SRIF persisted during synaptic blockade in two-thirds of neurons tested. The inhibitory effect of SRIF was reduced by picrotoxin, a GABAA receptor antagonist, in one-third of neurons. These results suggest that SRIF exerts an inhibitory effect on medial amygdala neurons through either a direct action on SRIF receptors or a GABAergic synaptic involvement.Key words: somatostatin, amygdala, brain slice, neuron activity, picrotoxin.
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Unda, Brianna K., Vickie Kwan, and Karun K. Singh. "Neuregulin-1 Regulates Cortical Inhibitory Neuron Dendrite and Synapse Growth through DISC1." Neural Plasticity 2016 (2016): 1–15. http://dx.doi.org/10.1155/2016/7694385.
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Cortical inhibitory neurons play crucial roles in regulating excitatory synaptic networks and cognitive function and aberrant development of these cells have been linked to neurodevelopmental disorders. The secreted neurotrophic factor Neuregulin-1 (NRG1) and its receptor ErbB4 are established regulators of inhibitory neuron connectivity, but the developmental signalling mechanisms regulating this process remain poorly understood. Here, we provide evidence that NRG1-ErbB4 signalling functions through the multifunctional scaffold protein, Disrupted in Schizophrenia 1 (DISC1), to regulate the development of cortical inhibitory interneuron dendrite and synaptic growth. We found that NRG1 increases inhibitory neuron dendrite complexity and glutamatergic synapse formation onto inhibitory neurons and that this effect is blocked by expression of a dominant negative DISC1 mutant, or DISC1 knockdown. We also discovered that NRG1 treatment increases DISC1 expression and its localization to glutamatergic synapses being made onto cortical inhibitory neurons. Mechanistically, we determined that DISC1 binds ErbB4 within cortical inhibitory neurons. Collectively, these data suggest that a NRG1-ErbB4-DISC1 signalling pathway regulates the development of cortical inhibitory neuron dendrite and synaptic growth. Given that NRG1, ErbB4, and DISC1 are schizophrenia-linked genes, these findings shed light on how independent risk factors may signal in a common developmental pathway that contributes to neural connectivity defects and disease pathogenesis.
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Christensen, Thomas A., and John G. Hildebrand. "Coincident Stimulation With Pheromone Components Improves Temporal Pattern Resolution in Central Olfactory Neurons." Journal of Neurophysiology 77, no. 2 (February 1, 1997): 775–81. http://dx.doi.org/10.1152/jn.1997.77.2.775.
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Christensen, Thomas A. and John G. Hildebrand. Coincident stimulation with pheromone components improves temporal pattern resolution in central olfactory neurons. J. Neurophysiol. 77: 775–781, 1997. Male moths must detect and resolve temporal discontinuities in the sex pheromonal odor signal emitted by a conspecific female moth to orient to and locate the odor source. We asked how sensory information about two key components of the pheromone influences the ability of certain sexually dimorphic projection (output) neurons in the primary olfactory center of the male moth's brain to encode the frequency and duration of discrete pulses of pheromone blends. Most of the male-specific projection neurons examined gave mixed postsynaptic responses, consisting of an early suppressive phase followed by activation of firing, to stimulation of the ipsilateral antenna with a blend of the two behaviorally essential pheromone components. Of 39 neurons tested, 33 were excited by the principal (most abundant) pheromone component but inhibited by another, less abundant but nevertheless essential component of the blend. We tested the ability of each neuron to encode intermittent pheromonal stimuli by delivering trains of 50-ms pulses of the two-component blend at progressively higher rates from 1 to 10 per second. There was a strong correlation between 1) the amplitude of the early inhibitory postsynaptic potential evoked by the second pheromone component and 2) the maximal rate of odor pulses that neuron could resolve ( r = 0.92). Projection neurons receiving stronger inhibitory input encoded the temporal pattern of the stimulus with higher fidelity. With the principal, excitatory component of the pheromone alone as the stimulus, the dynamic range for encoding stimulus intermittency was reduced in nearly 60% of the neurons tested. The greatest reductions were observed in those neurons that could be shown to receive the strongest inhibitory input from the second behaviorally essential component of the blend. We also tested the ability of these neurons to encode stimulus duration. Again there was a strong correlation between the strength of the inhibitory input to a neuron mediated by the second pheromone component and that neuron's ability to encode stimulus duration. Neurons that were strongly inhibited by the second component could accurately encode pulses of the blend from 50 to 500 ms in duration ( r = 0.94), but that ability was reduced in neurons receiving little or no inhibitory input ( r = 0.23). This study confirms that certain olfactory projection neurons respond optimally to a particular odor blend rather than to the individual components of the blend. The key components activate opposing synaptic inputs that enable this subset of central neurons to copy the duration and frequency of intermittent odor pulses that are a fundamental feature of airborne olfactory stimuli.
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Mruczek, Ryan E. B., and David L. Sheinberg. "Stimulus selectivity and response latency in putative inhibitory and excitatory neurons of the primate inferior temporal cortex." Journal of Neurophysiology 108, no. 10 (November 15, 2012): 2725–36. http://dx.doi.org/10.1152/jn.00618.2012.
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The cerebral cortex is composed of many distinct classes of neurons. Numerous studies have demonstrated corresponding differences in neuronal properties across cell types, but these comparisons have largely been limited to conditions outside of awake, behaving animals. Thus the functional role of the various cell types is not well understood. Here, we investigate differences in the functional properties of two widespread and broad classes of cells in inferior temporal cortex of macaque monkeys: inhibitory interneurons and excitatory projection cells. Cells were classified as putative inhibitory or putative excitatory neurons on the basis of their extracellular waveform characteristics (e.g., spike duration). Consistent with previous intracellular recordings in cortical slices, putative inhibitory neurons had higher spontaneous firing rates and higher stimulus-evoked firing rates than putative excitatory neurons. Additionally, putative excitatory neurons were more susceptible to spike waveform adaptation following very short interspike intervals. Finally, we compared two functional properties of each neuron's stimulus-evoked response: stimulus selectivity and response latency. First, putative excitatory neurons showed stronger stimulus selectivity compared with putative inhibitory neurons. Second, putative inhibitory neurons had shorter response latencies compared with putative excitatory neurons. Selectivity differences were maintained and latency differences were enhanced during a visual search task emulating more natural viewing conditions. Our results suggest that short-latency inhibitory responses are likely to sculpt visual processing in excitatory neurons, yielding a sparser visual representation.
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Armstrong, Eve, and Henry D. I. Abarbanel. "Model of the songbird nucleus HVC as a network of central pattern generators." Journal of Neurophysiology 116, no. 5 (November 1, 2016): 2405–19. http://dx.doi.org/10.1152/jn.00438.2016.
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We propose a functional architecture of the adult songbird nucleus HVC in which the core element is a “functional syllable unit” (FSU). In this model, HVC is organized into FSUs, each of which provides the basis for the production of one syllable in vocalization. Within each FSU, the inhibitory neuron population takes one of two operational states: 1) simultaneous firing wherein all inhibitory neurons fire simultaneously, and 2) competitive firing of the inhibitory neurons. Switching between these basic modes of activity is accomplished via changes in the synaptic strengths among the inhibitory neurons. The inhibitory neurons connect to excitatory projection neurons such that during state 1 the activity of projection neurons is suppressed, while during state 2 patterns of sequential firing of projection neurons can occur. The latter state is stabilized by feedback from the projection to the inhibitory neurons. Song composition for specific species is distinguished by the manner in which different FSUs are functionally connected to each other. Ours is a computational model built with biophysically based neurons. We illustrate that many observations of HVC activity are explained by the dynamics of the proposed population of FSUs, and we identify aspects of the model that are currently testable experimentally. In addition, and standing apart from the core features of an FSU, we propose that the transition between modes may be governed by the biophysical mechanism of neuromodulation.
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Segal, M. M. "Epileptiform activity in microcultures containing one excitatory hippocampal neuron." Journal of Neurophysiology 65, no. 4 (April 1, 1991): 761–70. http://dx.doi.org/10.1152/jn.1991.65.4.761.
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1. Paroxysmal depolarizing shifts (PDSs) occur during interictal epileptiform activity. Sustained depolarizations are characteristic of ictal activity, and events resembling PDSs also occur during the sustained depolarizations. To study these elements of epileptiform activity in a simpler context, I used the in vitro chronic-excitatory-block model of epilepsy of Furshpan and Potter and the microculture technique of Segal and Furshpan. 2. Intracellular recordings were made from 93 single-neuron microcultures. Forty of these solitary neurons were excitatory, their action potentials were replaced by PDS-like events or sustained depolarizations as kynurenate was removed from the perfusion solution. PDS-like events were similar to PDSs in intact cortex, mass cultures, and microcultures with more than one neuron. Small voltage fluctuations were also seen in solitary excitatory neurons in the absence of recorded action potentials. Sustained depolarizations developed in 5 of the 40 excitatory neurons. Forty-eight of the 93 solitary neurons were inhibitory, with bicuculline-sensitive hyperpolarizations after the action potential (ascribable to gamma-aminobutyric acid-A autapses). None of the solitary inhibitory neurons displayed sustained depolarizations. Five of the 93 neurons were insensitive to both kynurenate and bicuculline and were not placed in either the excitatory or the inhibitory category. 3. Both N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptors contributed to the PDS-like events and sustained depolarizations. Only a non-NMDA glutamate receptor component was evident for the small voltage fluctuations. 4. Intracellular recordings were also made from two-neuron microcultures, each containing one excitatory neuron and one inhibitory neuron. Sustained depolarizations developed in five microcultures, in each case only in the excitatory neuron.
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Zhang, Danke, Yuanqing Li, and Si Wu. "Concentration-Invariant Odor Representation in the Olfactory System by Presynaptic Inhibition." Computational and Mathematical Methods in Medicine 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/507143.
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The present study investigates a network model for implementing concentration-invariant representation for odors in the olfactory system. The network consists of olfactory receptor neurons, projection neurons, and inhibitory local neurons. Receptor neurons send excitatory inputs to projection neurons, which are modulated by the inhibitory inputs from local neurons. The modulation occurs at the presynaptic site from a receptor neuron to a projection one, leading to the operation of divisive normalization. The responses of local interneurons are determined by the total activities of olfactory receptor neurons. We find that with a proper parameter condition, the responses of projection neurons become effectively independent of the odor concentration. Simulation results confirm our theoretical analysis.
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Swensen, A. M., J. Golowasch, A. E. Christie, M. J. Coleman, M. P. Nusbaum, and E. Marder. "GABA and responses to GABA in the stomatogastric ganglion of the crab Cancer borealis." Journal of Experimental Biology 203, no. 14 (July 15, 2000): 2075–92. http://dx.doi.org/10.1242/jeb.203.14.2075.
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The multifunctional neural circuits in the crustacean stomatogastric ganglion (STG) are influenced by many small-molecule transmitters and neuropeptides that are co-localized in identified projection neurons to the STG. We describe the pattern of gamma-aminobutyric acid (GABA) immunoreactivity in the stomatogastric nervous system of the crab Cancer borealis and demonstrate biochemically the presence of authentic GABA in C. borealis. No STG somata show GABA immunoreactivity but, within the stomatogastric nervous system, GABA immunoreactivity co-localizes with several neuropeptides in two identified projection neurons, the modulatory proctolin neuron (MPN) and modulatory commissural neuron 1 (MCN1). To determine which actions of these neurons are evoked by GABA, it is necessary to determine the physiological actions of GABA on STG neurons. We therefore characterized the response of each type of STG neuron to focally applied GABA. All STG neurons responded to GABA. In some neurons, GABA evoked a picrotoxin-sensitive depolarizing, excitatory response with a reversal potential of approximately −40 mV. This response was also activated by muscimol. In many STG neurons, GABA evoked inhibitory responses with both K(+)- and Cl(−)-dependent components. Muscimol and beta-guanidinopropionic acid weakly activated the inhibitory responses, but many other drugs, including bicuculline and phaclofen, that act on vertebrate GABA receptors were not effective. In summary, GABA is found in projection neurons to the crab STG and can evoke both excitatory and inhibitory actions on STG neurons.
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Jo, Young-Hwan. "Endogenous BDNF regulates inhibitory synaptic transmission in the ventromedial nucleus of the hypothalamus." Journal of Neurophysiology 107, no. 1 (January 2012): 42–49. http://dx.doi.org/10.1152/jn.00353.2011.
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Output from steroidogenic factor-1 (SF-1) neurons in the ventromedial nucleus of the hypothalamus (VMH) is anorexigenic. SF-1 neurons express brain-derived neurotrophic factor (BDNF) that contributes to the regulation of food intake and body weight. Here I show that regulation of GABAergic inputs onto SF-1 neurons by endogenous BDNF determines the anorexigenic outcome from the VMH. Single-cell RT-PCR analysis reveals that one-third of SF-1 neurons express BDNF and that only a subset of BDNF-expressing SF-1 neurons coexpresses the melanocortin receptor type 4. Whole cell patch-clamp analysis of SF-1 neurons in the VMH shows that exogenous BDNF significantly increases the frequency of spontaneous GABAergic inhibitory postsynaptic currents (sIPSCs). This enhancement of GABA drive readily decreases the excitability of SF-1 neurons. However, treatment with BDNF has no significant effect on the frequency of TTX-independent GABAergic IPSCs. Moreover, TrkB receptors are not localized at the postsynaptic sites of GABAergic synapses on SF-1 neurons as there is no change in the amplitude of miniature IPSCs in the presence of BDNF. Dual patch-clamp recordings in mouse hypothalamic slices reveal that stimulation of one SF-1 neuron induces an increase in sIPSC frequency onto the neighboring SF-1 neuron. More importantly, this effect is blocked by a tyrosine kinase inhibitor. Hence, this increased GABA drive onto SF-1 neurons may, in part, explain the cellular mechanisms that mediate the anorexigenic effects of BDNF.
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Kanamaru, Takashi, and Kazuyuki Aihara. "Stochastic Synchrony of Chaos in a Pulse-Coupled Neural Network with Both Chemical and Electrical Synapses Among Inhibitory Neurons." Neural Computation 20, no. 8 (August 2008): 1951–72. http://dx.doi.org/10.1162/neco.2008.05-07-516.
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The synchronous firing of neurons in a pulse-coupled neural network composed of excitatory and inhibitory neurons is analyzed. The neurons are connected by both chemical synapses and electrical synapses among the inhibitory neurons. When electrical synapses are introduced, periodically synchronized firing as well as chaotically synchronized firing is widely observed. Moreover, we find stochastic synchrony where the ensemble-averaged dynamics shows synchronization in the network but each neuron has a low firing rate and the firing of the neurons seems to be stochastic. Stochastic synchrony of chaos corresponding to a chaotic attractor is also found.
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Shu, Yousheng, and David A. McCormick. "Inhibitory Interactions Between Ferret Thalamic Reticular Neurons." Journal of Neurophysiology 87, no. 5 (May 1, 2002): 2571–76. http://dx.doi.org/10.1152/jn.00850.2001.
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The thalamic reticular nucleus (nRt) provides an important inhibitory input to thalamic relay nuclei and is central in the generation of both normal and abnormal thalamocortical activities. Although local inhibitory interactions between these neurons may play an important role in controlling thalamocortical activities, the physiological features of this interaction have not been fully investigated. Here we sought to establish the nature of inhibitory interaction between nRt neurons with intracellular and extracellular recordings in slices of ferret nRt maintained in vitro. In many nRt neurons, intracellular recordings revealed spontaneous inhibitory postsynaptic potentials (IPSPs). In addition, the local excitation of nRt cells with glutamate led to the generation of IPSPs in the intracellularly recorded nRt neuron. These evoked IPSPs exhibited an average reversal potential of −72 mV and could be blocked by picrotoxin, a GABAA-receptor antagonist. These results indicate that nRt neurons interact locally through the activation of GABAA receptor-mediated inhibitory postsynaptic potentials. This lateral inhibition may play an important role in controlling the responsiveness of these cells to cortical and thalamic excitatory inputs in both normal and abnormal thalamocortical function.
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Murray, Peter D., and Asaf Keller. "Somatosensory response properties of excitatory and inhibitory neurons in rat motor cortex." Journal of Neurophysiology 106, no. 3 (September 2011): 1355–62. http://dx.doi.org/10.1152/jn.01089.2010.
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In sensory cortical networks, peripheral inputs differentially activate excitatory and inhibitory neurons. Inhibitory neurons typically have larger responses and broader receptive field tuning compared with excitatory neurons. These differences are thought to underlie the powerful feedforward inhibition that occurs in response to sensory input. In the motor cortex, as in the somatosensory cortex, cutaneous and proprioceptive somatosensory inputs, generated before and during movement, strongly and dynamically modulate the activity of motor neurons involved in a movement and ultimately shape cortical command. Human studies suggest that somatosensory inputs modulate motor cortical activity in a center excitation, surround inhibition manner such that input from the activated muscle excites motor cortical neurons that project to it, whereas somatosensory input from nearby, nonactivated muscles inhibit these neurons. A key prediction of this hypothesis is that inhibitory and excitatory motor cortical neurons respond differently to somatosensory inputs. We tested this prediction with the use of multisite extracellular recordings in anesthetized rats. We found that fast-spiking (presumably inhibitory) neurons respond to tactile and proprioceptive inputs at shorter latencies and larger response magnitudes compared with regular-spiking (presumably excitatory) neurons. In contrast, we found no differences in the receptive field size of these neuronal populations. Strikingly, all fast-spiking neuron pairs analyzed with cross-correlation analysis displayed common excitation, which was significantly more prevalent than common excitation for regular-spiking neuron pairs. These findings suggest that somatosensory inputs preferentially evoke feedforward inhibition in the motor cortex. We suggest that this provides a mechanism for dynamic selection of motor cortical modules during voluntary movements.
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Lalley, Peter M., Olivier Pierrefiche, Anne M. Bischoff, and Diethelm W. Richter. "cAMP-Dependent Protein Kinase Modulates Expiratory Neurons In Vivo." Journal of Neurophysiology 77, no. 3 (March 1, 1997): 1119–31. http://dx.doi.org/10.1152/jn.1997.77.3.1119.
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Lalley, Peter M., Olivier Pierrefiche, Anne M. Bischoff, and Diethelm W. Richter. cAMP-dependent protein kinase modulates expiratory neurons in vivo. J. Neurophysiol. 77: 1119–1131, 1997. The adenosine 3′,5′-cyclic monophosphate (cAMP)-dependent protein kinase (PKA) second-messenger system influences neuronal excitability by modulating voltage-regulated and transmitter-activated channels. In this study we investigated the influence of the cAMP-PKA system on the excitability of expiratory (E) neurons in the caudal medulla of anesthetized, paralyzed, and artificially ventilated adult cats. We intracellularly injected the PKA inhibitors cAMP-dependent PKA inhibitor 5-22 amide (Walsh inhibitory peptide) and Rp-adenosine 3′,5′-cyclic monophosphothioate triethylamine (Rp-cAMPS), the PKA activator Sp-adenosine 3′,5′-cyclic monophosphothioate triethylamine (Sp-cAMPS), and the adenylyl cyclase activator forskolin and measured membrane potential, neuronal input resistance, and synaptic membrane currents. Inhibition of cAMP-PKA activity by Walsh inhibitory peptide or Rp-cAMPS injections hyperpolarized neurons, decreased input resistance, and depressed spontaneous bursts of action potentials. Action potential duration was shortened and afterhyperpolarizations were increased. Inhibitory synaptic currents increased significantly. Stimulation of cAMP-PKA activity by Sp-cAMPS or forskolin depolarized neurons and increased input resistance. Spontaneous inhibitory synaptic currents were reduced and excitatory synaptic currents were increased. Rp-cAMPS depressed stimulus-evoked excitatory postsynaptic potentials and currents, whereas Sp-cAMPS increased them. Sp-cAMPS also blocked postsynaptic inhibition of E neurons by 8-hydroxy-dipropylaminotetralin, a serotonin-1A (5-HT-1A) receptor agonist that depresses neuronal cAMP-PKA activity. To determine the predominant effect of G protein-mediated neuromodulation of E neurons, we injected guanosine-5′-O-(3-thiotriphosphate) tetralithium salt (GTP-γ-S), an activator of both stimulatory and inhibitory G proteins. GTP-γ-S hyperpolarized E neurons, reduced input resistance, and increased action potential afterhyperpolarization. We conclude that the intracellular cAMP-PKA messenger system plays an important role in the activity-dependent modulation of excitability in E neurons of the caudal medulla. In addition, the cAMP-PKA pathway itself is downregulated during activation of 5-HT-1A receptors.
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Rutishauser, Ueli, Jean-Jacques Slotine, and Rodney J. Douglas. "Competition Through Selective Inhibitory Synchrony." Neural Computation 24, no. 8 (August 2012): 2033–52. http://dx.doi.org/10.1162/neco_a_00304.
Full textAbstract:
Models of cortical neuronal circuits commonly depend on inhibitory feedback to control gain, provide signal normalization, and selectively amplify signals using winner-take-all (WTA) dynamics. Such models generally assume that excitatory and inhibitory neurons are able to interact easily because their axons and dendrites are colocalized in the same small volume. However, quantitative neuroanatomical studies of the dimensions of axonal and dendritic trees of neurons in the neocortex show that this colocalization assumption is not valid. In this letter, we describe a simple modification to the WTA circuit design that permits the effects of distributed inhibitory neurons to be coupled through synchronization, and so allows a single WTA to be distributed widely in cortical space, well beyond the arborization of any single inhibitory neuron and even across different cortical areas. We prove by nonlinear contraction analysis and demonstrate by simulation that distributed WTA subsystems combined by such inhibitory synchrony are inherently stable. We show analytically that synchronization is substantially faster than winner selection. This circuit mechanism allows networks of independent WTAs to fully or partially compete with other.
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Geisler, Caroline, Nicolas Brunel, and Xiao-Jing Wang. "Contributions of Intrinsic Membrane Dynamics to Fast Network Oscillations With Irregular Neuronal Discharges." Journal of Neurophysiology 94, no. 6 (December 2005): 4344–61. http://dx.doi.org/10.1152/jn.00510.2004.
Full textAbstract:
During fast oscillations in the local field potential (40–100 Hz gamma, 100–200 Hz sharp-wave ripples) single cortical neurons typically fire irregularly at rates that are much lower than the oscillation frequency. Recent computational studies have provided a mathematical description of such fast oscillations, using the leaky integrate-and-fire (LIF) neuron model. Here, we extend this theoretical framework to populations of more realistic Hodgkin–Huxley-type conductance-based neurons. In a noisy network of GABAergic neurons that are connected randomly and sparsely by chemical synapses, coherent oscillations emerge with a frequency that depends sensitively on the single cell's membrane dynamics. The population frequency can be predicted analytically from the synaptic time constants and the preferred phase of discharge during the oscillatory cycle of a single cell subjected to noisy sinusoidal input. The latter depends significantly on the single cell's membrane properties and can be understood in the context of the simplified exponential integrate-and-fire (EIF) neuron. We find that 200-Hz oscillations can be generated, provided the effective input conductance of single cells is large, so that the single neuron's phase shift is sufficiently small. In a two-population network of excitatory pyramidal cells and inhibitory neurons, recurrent excitation can either decrease or increase the population rhythmic frequency, depending on whether in a neuron the excitatory synaptic current follows or precedes the inhibitory synaptic current in an oscillatory cycle. Detailed single-cell properties have a substantial impact on population oscillations, even though rhythmicity does not originate from pacemaker neurons and is an emergent network phenomenon.
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Norekian, T. P., and R. A. Satterlie. "Whole body withdrawal circuit and its involvement in the behavioral hierarchy of the mollusk Clione limacina." Journal of Neurophysiology 75, no. 2 (February 1, 1996): 529–37. http://dx.doi.org/10.1152/jn.1996.75.2.529.
Full textAbstract:
1. The behavioral repertoire of the holoplanktonic pteropod mollusk Clione limacina includes a few well-defined behaviors organized in a priority sequence. Whole body withdrawal takes precedence over slow swimming behavior, whereas feeding behavior is dominant over withdrawal. In this study a group of neurons is described in the pleural ganglia, which controls whole body withdrawal behavior in Clione. Each pleural withdrawal (Pl-W) neuron has a high threshold for spike generation and is capable of inducing whole body withdrawal in a semi-intact preparation: retraction of the body-tail, wings, and head. Each Pl-W neuron projects axons into the main central nerves and innervates all major regions of the body. 2. Stimulation of Pl-W neurons produces inhibitory inputs to swim motor neurons that terminate swimming activity in the preparation. In turn, Pl-W neurons receive inhibitory inputs from the cerebral neurons involved in the control of feeding behavior in Clione, neurons underlying extrusion of specialized prey capture appendages. Thus it appears that specific inhibitory connections between motor centers can explain the dominance of withdrawal behavior over slow swimming and feeding over withdrawal in Clione.
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Holmstrom, Lars, Patrick D. Roberts, and Christine V. Portfors. "Responses to Social Vocalizations in the Inferior Colliculus of the Mustached Bat Are Influenced by Secondary Tuning Curves." Journal of Neurophysiology 98, no. 6 (December 2007): 3461–72. http://dx.doi.org/10.1152/jn.00638.2007.
Full textAbstract:
Neurons in the inferior colliculus (IC) of the mustached bat integrate input from multiple frequency bands in a complex fashion. These neurons are important for encoding the bat's echolocation and social vocalizations. The purpose of this study was to quantify the contribution of complex frequency interactions on the responses of IC neurons to social vocalizations. Neural responses to single tones, two-tone pairs, and social vocalizations were recorded in the IC of the mustached bat. Three types of data driven stimulus-response models were designed for each neuron from single tone and tone pair stimuli to predict the responses of individual neurons to social vocalizations. The first model was generated only using the neuron's primary frequency tuning curve, whereas the second model incorporated the entire hearing range of the animal. The extended model often predicted responses to many social vocalizations more accurately for multiply tuned neurons. One class of multiply tuned neuron that likely encodes echolocation information also responded to many of the social vocalizations, suggesting that some neurons in the mustached bat IC have dual functions. The third model included two-tone frequency tunings of the neurons. The responses to vocalizations were better predicted by the two-tone models when the neuron had inhibitory frequency tuning curves that were not near the neuron's primary tuning curve. Our results suggest that complex frequency interactions in the IC determine neural responses to social vocalizations and some neurons in IC have dual functions that encode both echolocation and social vocalization signals.
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Naumov, Victor, Julia Heyd, Fauve de Arnal, and Ursula Koch. "Analysis of excitatory and inhibitory neuron types in the inferior colliculus based on Ih properties." Journal of Neurophysiology 121, no. 6 (June 1, 2019): 2126–39. http://dx.doi.org/10.1152/jn.00594.2018.
Full textAbstract:
The inferior colliculus (IC) is a large midbrain nucleus that integrates inputs from many auditory brainstem and cortical structures. Despite its prominent role in auditory processing, the various cell types and their connections within the IC are not well characterized. To further separate GABAergic and non-GABAergic neuron types according to their physiological properties, we used a mouse model that expresses channelrhodopsin and enhanced yellow fluorescent protein in all GABAergic neurons and allows identification of GABAergic cells by light stimulation. Neuron types were classified upon electrophysiological measurements of the hyperpolarizing-activated current ( Ih) in acute brain slices of young adult mice. All GABAergic neurons from our sample displayed slow-activating Ih with moderate amplitudes, whereas a subset of excitatory neurons showed fast-activating Ih with large amplitudes. This is in agreement with our finding that immunoreactivity against the fast-gating hyperpolarization-activated and cyclic-nucleotide-gated 1 (HCN1) channel was present around excitatory neurons, whereas the slow-gating HCN4 channel was found perisomatically around most inhibitory neurons. Ih properties and neurotransmitter types were correlated with firing patterns to depolarizing current pulses. All GABAergic neurons displayed adapting firing patterns very similar to the majority of glutamatergic neurons. About 15% of the glutamatergic neurons showed an onset spiking pattern, always in combination with large and fast Ih. We conclude that HCN channel subtypes are differentially distributed in IC neuron types and correlate with neurotransmitter type and firing pattern. In contrast to many other brain regions, membrane properties and firing patterns were similar in GABAergic neurons and about one-third of the excitatory neurons. NEW & NOTEWORTHY Neuron types in the central nucleus of the auditory midbrain are not well characterized regarding their transmitter type, ion channel composition, and firing pattern. The present study shows that GABAergic neurons have slowly activating hyperpolarizing-activated current ( Ih) and an adaptive firing pattern whereas at least four types of glutamatergic neurons exist regarding their Ih properties and firing patterns. Many of the glutamatergic neurons were almost indistinguishable from the GABAergic neurons regarding Ih properties and firing pattern.
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Zhou, Fu-Wen, Jian-Jun Xu, Yu Zhao, Mark S. LeDoux, and Fu-Ming Zhou. "Opposite Functions of Histamine H1 and H2 Receptors and H3 Receptor in Substantia Nigra Pars Reticulata." Journal of Neurophysiology 96, no. 3 (September 2006): 1581–91. http://dx.doi.org/10.1152/jn.00148.2006.
Full textAbstract:
The substantia nigra pars reticulata (SNr) is a key basal ganglia output nucleus. Inhibitory outputs from SNr are encoded in spike frequency and pattern of the inhibitory SNr projection neurons. SNr output intensity and pattern are often abnormal in movement disorders of basal ganglia origin. In Parkinson’s disease, histamine innervation and histamine H3 receptor expression in SNr may be increased. However, the functional consequences of these alterations are not known. In this study, whole cell patch-clamp recordings were used to elucidate the function of different histamine receptors in SNr. Histamine increased SNr inhibitory projection neuron firing frequency and thus inhibitory output. This effect was mediated by activation of histamine H1 and H2 receptors that induced inward currents and depolarization. In contrast, histamine H3 receptor activation hyperpolarized and inhibited SNr inhibitory projection neurons, thus decreasing the intensity of basal ganglia output. By the hyperpolarization, H3 receptor activation also increased the irregularity of the interspike intervals or changed the pattern of SNr inhibitory neuron firing. H3 receptor–mediated effects were normally dominated by those mediated by H1 and H2 receptors. Furthermore, endogenously released histamine provided a tonic, H1 and H2 receptor–mediated excitation that helped keep SNr inhibitory projection neurons sufficiently depolarized and spiking regularly. These results suggest that H1 and H2 receptors and H3 receptor exert opposite effects on SNr inhibitory projection neurons. Functional balance of these different histamine receptors may contribute to the proper intensity and pattern of basal ganglia output and, as a consequence, exert important effects on motor control.
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Tanibuchi, Ikuo, Hiroyuki Kitano, and Kohnosuke Jinnai. "Substantia Nigra Output to Prefrontal Cortex Via Thalamus in Monkeys. I. Electrophysiological Identification of Thalamic Relay Neurons." Journal of Neurophysiology 102, no. 5 (November 2009): 2933–45. http://dx.doi.org/10.1152/jn.91287.2008.
Full textAbstract:
A few studies have been performed in primate basal ganglia–thalamo–prefrontal pathways. Nevertheless, their electrophysiological properties and anatomical arrangements remain obscure. This study examined them in nigro-thalamo-cortical pathways from the substantia nigra pars reticulata (SNr) to the frontal cortex (FRC) via the mediodorsal (MD) and ventral anterior (VA) thalamus in monkeys. First, single thalamocortical neurons with SNr input were identified by antidromic responses to FRC stimulation and by inhibitory orthodromic responses with short latencies (<5 ms) to SNr stimulation. Second, single nigrothalamic neurons were found by antidromic responses to stimulation of the portions of the MD and VA where the thalamocortical neurons were recorded. The inhibitory orthodromic responses in the thalamocortical neurons were considered to be monosynaptically induced by nigral stimulation because the latency distribution of the orthodromic responses in the thalamocortical neurons was similar to that of the antidromic responses in the nigrothalamic neurons. Almost all relay neurons in the rostrolateral MD received inhibitory afferents from the caudolateral SNr and projected to the prefrontal area ventral to the principal sulcus, which constituted the densest nigro-thalamo-cortical projections. Meanwhile, neurons in the VA received inhibitory signals from the whole rostrocaudal extent of the SNr and projected to wide regions of the FRC; neurons in its pars magnocellularis mostly projected to different prefrontal areas, while those in its pars parvocellularis projected to motor areas. This report substantiated the topography of thalamocortical neurons monosynaptically receiving inhibitory SNr input and projecting to the FRC in the primate MD and VA at the single-neuron level.
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Camp, Aaron J., Robert J. Callister, and Alan M. Brichta. "Inhibitory Synaptic Transmission Differs in Mouse Type A and B Medial Vestibular Nucleus Neurons In Vitro." Journal of Neurophysiology 95, no. 5 (May 2006): 3208–18. http://dx.doi.org/10.1152/jn.01001.2005.
Full textAbstract:
Fast inhibitory synaptic transmission in the medial vestibular nucleus (MVN) is mediated by GABAA receptors (GABAARs) and glycine receptors (GlyRs). To assess their relative contribution to inhibition in the MVN, we recorded miniature inhibitory postsynaptic currents (mIPSCs) in physiologically characterized type A and type B MVN neurons. Transverse brain stem slices were prepared from mice (3–8 wk old), and whole cell patch-clamp recordings were obtained from visualized MVN neurons (CsCl internal; Vm = –70 mV; 23°C). In 81 MVN neurons, 69% received exclusively GABAAergic inputs, 6% exclusively glycinergic inputs, and 25% received both types of mIPSCs. The mean amplitude of GABAAR-mediated mIPSCs was smaller than those mediated by GlyRs (22.6 ± 1.8 vs. 35.3 ± 5.3 pA). The rise time and decay time constants of GABAAR- versus GlyR-mediated mIPSCs were slower (1.3 ± 0.1 vs. 0.9 ± 0.1 ms and 10.5 ± 0.3 vs. 4.7 ± 0.3 ms, respectively). Comparison of type A ( n = 20) and type B ( n = 32) neurons showed that type A neurons received almost exclusively GABAAergic inhibitory inputs, whereas type B neurons received GABAAergic inputs, glycinergic inputs, or both. Intracellular labeling in a subset of MVN neurons showed that morphology was not related to a MVN neuron's inhibitory profile ( n = 15), or whether it was classified as type A or B ( n = 29). Together, these findings indicate that both GABA and glycine contribute to inhibitory synaptic processing in MVN neurons, although GABA dominates and there is a difference in the distribution of GABAA and Gly receptors between type A and type B MVN neurons.
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Obrietan, Karl, and Anthony van den Pol. "GABAB Receptor-Mediated Regulation of Glutamate-Activated Calcium Transients in Hypothalamic and Cortical Neuron Development." Journal of Neurophysiology 82, no. 1 (July 1, 1999): 94–102. http://dx.doi.org/10.1152/jn.1999.82.1.94.
Full textAbstract:
In the mature nervous system excitatory neurotransmission mediated by glutamate is balanced by the inhibitory actions of GABA. However, during early development, GABA acting at the ligand-gated GABAA Cl− channel also exerts excitatory actions. This raises a question as to whether GABA can exert inhibitory activity during early development, possibly by a mechanism that involves activation of the G protein-coupled GABABreceptor. To address this question we used Ca2+ digital imaging to assess the modulatory role of GABAB receptor signaling in relation to the excitatory effects of glutamate during hypothalamic and cortical neuron development. Ca2+transients mediated by synaptic glutamate release in neurons cultured from embryonic rat were dramatically depressed by the administration of the GABAB receptor agonist baclofen in a dose-dependent manner. The inhibitory effects of GABAB receptor activation persisted for the duration of baclofen administration (>10 min). Preincubation with the Gi protein inhibitor pertussis toxin resulted in a substantial decrease in the inhibitory actions of baclofen, confirming that a Gi-dependent mechanism mediated the effects of the GABAB receptor. Co-administration of the GABABreceptor antagonist 2-hydroxy-saclofen eliminated the inhibitory action of baclofen. Alone, GABAB antagonist application elicited a marked potentiation of Ca2+ transients mediated by glutamatergic neurotransmission, suggesting that tonic synaptic GABA release exerts an inhibitory tone on glutamate receptor-mediated Ca2+ transients via GABAB receptor activation. In the presence of TTX to block action potential-mediated neurotransmitter release, stimulation with exogenously applied glutamate triggered a robust postsynaptic Ca2+ rise that was dramatically depressed (>70% in cortical neurons, >40% in hypothalamic neurons) by baclofen. Together these data suggest both a pre- and postsynaptic component for the modulatory actions of the GABAB receptor. These results indicate a potentially important role for the GABAB receptor as a modulator of the excitatory actions of glutamate in developing neurons.
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Yang, Sunggu, and Charles L. Cox. "Modulation of Inhibitory Activity by Nitric Oxide in the Thalamus." Journal of Neurophysiology 97, no. 5 (May 2007): 3386–95. http://dx.doi.org/10.1152/jn.01270.2006.
Full textAbstract:
The dorsal lateral geniculate nucleus (dLGN) is essential for the transfer of visual information from the retina to visual cortex, and inhibitory mechanisms can play a critical in regulating such information transfer. Nitric oxide (NO) is an atypical neuromodulator that is released in gaseous form and can alter neural activity without direct synaptic connections. Nitric oxide synthase (NOS), an essential enzyme for NO production, is localized in thalamic inhibitory neurons and cholinergic brain stem neurons that innervate the thalamus, although NO-mediated effects on thalamic inhibitory activity remain unknown. We investigated NO effects on inhibitory activity in dLGN using an in vitro slice preparation. The NO donor, SNAP, selectively potentiated the frequency, but not amplitude, of spontaneous inhibitory postsynaptic currents (sIPSCs) in thalamocortical relay neurons. This increase also persisted in tetrodotoxin (TTX), consistent with an increase in GABA release from presynaptic terminals. The SNAP-mediated actions were attenuated not only by the NO scavenger carboxy-PTIO but also by the guanylyl cyclase inhibitor ODQ. The endogenous NO precursor l-arginine produced actions similar to those of SNAP on sIPSC activity and these l-arginine–mediated actions were attenuated by the NOS inhibitor L-NMMA acetate. The SNAP-mediated increase in sIPSC activity was observed in both dLGN and ventrobasal thalamic nucleus (VB) neurons. Considering the lack of interneurons in rodent VB, the NO-mediated actions likely involve an increase in the output of axon terminals of thalamic reticular nucleus neurons. Our results indicate that NO upregulates thalamic inhibitory activity and thus these actions likely influence sensory information transfer through thalamocortical circuits.
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Lee, Seong-Eun, and Gum Hwa Lee. "Reelin Affects Signaling Pathways of a Group of Inhibitory Neurons and the Development of Inhibitory Synapses in Primary Neurons." International Journal of Molecular Sciences 22, no. 14 (July 13, 2021): 7510. http://dx.doi.org/10.3390/ijms22147510.
Full textAbstract:
Reelin is a secretory protein involved in a variety of processes in forebrain development and function, including neuronal migration, dendrite growth, spine formation, and synaptic plasticity. Most of the function of Reelin is focused on excitatory neurons; however, little is known about its effects on inhibitory neurons and inhibitory synapses. In this study, we investigated the phosphatidylinositol 3-kinase/Akt pathway of Reelin in primary cortical and hippocampal neurons. Individual neurons were visualized using immunofluorescence to distinguish inhibitory neurons from excitatory neurons. Reelin-rich protein supplementation significantly induced the phosphorylation of Akt and ribosomal S6 protein in excitatory neurons, but not in most inhibitory neurons. In somatostatin-expressing inhibitory neurons, one of major subtypes of inhibitory neurons, Reelin-rich protein supplementation induced the phosphorylation of S6. Subsequently, we investigated whether or not Reelin-rich protein supplementation affected dendrite development in cultured inhibitory neurons. Reelin-rich protein supplementation did not change the total length of dendrites in inhibitory neurons in vitro. Finally, we examined the development of inhibitory synapses in primary hippocampal neurons and found that Reelin-rich protein supplementation significantly reduced the density of gephyrin–VGAT-positive clusters in the dendritic regions without changing the expression levels of several inhibitory synapse-related proteins. These findings indicate a new role for Reelin in specific groups of inhibitory neurons and the development of inhibitory synapses, which may contribute to the underlying cellular mechanisms of RELN-associated neurological disorders.
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Pesavento, Michael J., and David J. Pinto. "Network and neuronal membrane properties in hybrid networks reciprocally regulate selectivity to rapid thalamocortical inputs." Journal of Neurophysiology 108, no. 9 (November 1, 2012): 2452–72. http://dx.doi.org/10.1152/jn.00914.2011.
Full textAbstract:
Rapidly changing environments require rapid processing from sensory inputs. Varying deflection velocities of a rodent's primary facial vibrissa cause varying temporal neuronal activity profiles within the ventral posteromedial thalamic nucleus. Local neuron populations in a single somatosensory layer 4 barrel transform sparsely coded input into a spike count based on the input's temporal profile. We investigate this transformation by creating a barrel-like hybrid network with whole cell recordings of in vitro neurons from a cortical slice preparation, embedding the biological neuron in the simulated network by presenting virtual synaptic conductances via a conductance clamp. Utilizing the hybrid network, we examine the reciprocal network properties (local excitatory and inhibitory synaptic convergence) and neuronal membrane properties (input resistance) by altering the barrel population response to diverse thalamic input. In the presence of local network input, neurons are more selective to thalamic input timing; this arises from strong feedforward inhibition. Strongly inhibitory (damping) network regimes are more selective to timing and less selective to the magnitude of input but require stronger initial input. Input selectivity relies heavily on the different membrane properties of excitatory and inhibitory neurons. When inhibitory and excitatory neurons had identical membrane properties, the sensitivity of in vitro neurons to temporal vs. magnitude features of input was substantially reduced. Increasing the mean leak conductance of the inhibitory cells decreased the network's temporal sensitivity, whereas increasing excitatory leak conductance enhanced magnitude sensitivity. Local network synapses are essential in shaping thalamic input, and differing membrane properties of functional classes reciprocally modulate this effect.
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Cardi, P., and F. Nagy. "A rhythmic modulatory gating system in the stomatogastric nervous system of Homarus gammarus. III. Rhythmic control of the pyloric CPG." Journal of Neurophysiology 71, no. 6 (June 1, 1994): 2503–16. http://dx.doi.org/10.1152/jn.1994.71.6.2503.
Full textAbstract:
1. Two modulatory neurons, P and commissural pyloric (CP), known to be involved in the long-term maintenance of pyloric central pattern generator operation in the rock lobster Homarus gammarus, are members of the commissural pyloric oscillator (CPO), a higher-order oscillator influencing the pyloric network. 2. The CP neuron was endogenously oscillating in approximately 30% of the preparations in which its cell body was impaled. Rhythmic inhibitory feedback from the pyloric pacemaker anterior burster (AB) neuron stabilized the CP neuron's endogenous rhythm. 3. The organization of the CPO is described. Follower commissural neurons, the F cells, and the CP neuron receive a common excitatory postsynaptic potential from another commissural neuron, the large exciter (LE). When in oscillatory state, CP in turn excites the LE neuron. This positive feedback may maintain long episodes of CP oscillations. 4. The pyloric pacemaker neurons follow the CPO rhythm with variable coordination modes (i.e., 1:1, 1:2) and switch among these modes when their membrane potential is modified. The CPO inputs strongly constrain the pyloric period, which as a result may adopt only a few discrete values. This effect is based on mechanisms of entrainment between the CPO and the pyloric oscillator. 5. Pyloric constrictor neurons show differential sensitivity from the pyloric pacemaker neurons with respect to the CPO inputs. Consequently, their bursting period can be a shorter harmonic of the bursting period of the pyloric pacemakers neurons. 6. The CPO neurons seem to be the first example of modulatory gating neurons that also give timing cues to a rhythmic pattern generating network.
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YAMAZAKI, TADASHI, and SHIGERU TANAKA. "A NEURAL NETWORK MODEL FOR TRACE CONDITIONING." International Journal of Neural Systems 15, no. 01n02 (February 2005): 23–30. http://dx.doi.org/10.1142/s0129065705000037.
Full textAbstract:
We studied the dynamics of a neural network that has both recurrent excitatory and random inhibitory connections. Neurons started to become active when a relatively weak transient excitatory signal was presented and the activity was sustained due to the recurrent excitatory connections. The sustained activity stopped when a strong transient signal was presented or when neurons were disinhibited. The random inhibitory connections modulated the activity patterns of neurons so that the patterns evolved without recurrence with time. Hence, a time passage between the onsets of the two transient signals was represented by the sequence of activity patterns. We then applied this model to represent the trace eyeblink conditioning, which is mediated by the hippocampus. We assumed this model as CA3 of the hippocampus and considered an output neuron corresponding to a neuron in CA1. The activity pattern of the output neuron was similar to that of CA1 neurons during trace eyeblink conditioning, which was experimentally observed.
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Keerthana B, Yuvaraj Babu K, and Gayathri R. "Rosehip Neuron - A Review." International Journal of Research in Pharmaceutical Sciences 11, SPL3 (September 8, 2020): 53–59. http://dx.doi.org/10.26452/ijrps.v11ispl3.2890.
Full textAbstract:
Rosehip neuron is a special type of neuron present only in humans. It has inhibitory actions over other cells. It is present in the first layer of the human cerebral cortex. These neurons have an inhibitory action over other neuronal cells. This research is seen as a scoping literature review. In seeking to identify the relevant literature from the past twenty years, we used common databases such as Pubmed, Google scholar online websites. Nearly 30 reference articles are collected related to the topic. The obtained articles were later read thoroughly and understood. Rosehip neurons are unique neurons and can treat neuronal disorders. It can also maintain the activities of other neuronal cells. It is concluded that more research has to be done on the actions of rosehip neurons and about its functions. This review is an attempt to understand the various functions of Rosehip neurons in humans. Further research is needed to know about its full use of humanity.
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Norekian, T. P., and R. A. Satterlie. "Cerebral serotonergic neurons reciprocally modulate swim and withdrawal neural networks in the mollusk Clione limacina." Journal of Neurophysiology 75, no. 2 (February 1, 1996): 538–46. http://dx.doi.org/10.1152/jn.1996.75.2.538.
Full textAbstract:
1. A pair of serotonin-immunoreactive neurons has been identified in the cerebral ganglia of the pteropod mollusk Clione limacina, which produce coordinated, excitatory/inhibitory effects on neurons controlling two incompatible behaviors, swimming and whole body withdrawal. These cells were designated cerebral serotonergic ventral (Cr-SV) neurons. 2. Activation of Cr-SV neurons produces a prominent inhibition of the pleural withdrawal neurons, which have been previously shown to induce whole body withdrawal in Clione. In addition, the cerebral neurons produce weak excitatory inputs to swim motor neurons, pedal serotonergic neurons involved in the peripheral modulation of swimming, and to the serotonergic heart excitor neuron. 3. Inhibitory and excitatory effects appear to be produced by serotonin because they are mimicked by exogenous serotonin and are blocked by the serotonin antagonist mianserin. 4. All serotonergic neurons identified thus far in the CNS of Clione appear to function in a coordinated manner, altering a variety of neural centers all directed toward the activation of swimming behavior.
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Buhler, A. V., and T. V. Dunwiddie. "α7 Nicotinic Acetylcholine Receptors on GABAergic Interneurons Evoke Dendritic and Somatic Inhibition of Hippocampal Neurons." Journal of Neurophysiology 87, no. 1 (January 1, 2002): 548–57. http://dx.doi.org/10.1152/jn.00316.2001.
Full textAbstract:
GABAergic interneurons in the hippocampus express high levels of α7 nicotinic acetylcholine receptors, but because of the diverse roles played by hippocampal interneurons, the impact of activation of these receptors on hippocampal output neurons (i.e., CA1 pyramidal cells) is unclear. Activation of hippocampal interneurons could directly inhibit pyramidal neuron activity but could also produce inhibition of other GABAergic cells leading to disinhibition of pyramidal cells. To characterize the inhibitory circuits activated by these receptors, exogenous acetylcholine was applied directly to CA1 interneurons in hippocampal slices, and the resulting postsynaptic responses were recorded from pyramidal neurons or interneurons. Inhibitory currents mediated by GABAA receptors were observed in 27/131 interneuron/pyramidal cell pairs, but no instances of disinhibition of spontaneous inhibitory events or GABAB receptor-mediated responses were observed. Two populations of bicuculline-sensitive GABAAreceptor-mediated currents could be distinguished based on their kinetics and amplitude. Anatomical reconstructions of the interneurons in a subset of connected pairs support the hypothesis that these two populations correspond to inhibitory synapses located either on the somata or dendrites of pyramidal cells. In 11 interneuron/interneuron cell pairs, one presynaptic neuron was observed that produced strong inhibitory currents in several nearby interneurons, suggesting that disinhibition of pyramidal neurons may also occur. All three types of inhibitory responses (somatic-pyramidal, dendritic-pyramidal, and interneuronal) were blocked by the α7 receptor-selective antagonist methyllycaconitine. These data suggest activation of these functionally distinct circuits by α7 receptors results in significant inhibition of both hippocampal pyramidal neurons as well as interneurons.
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Robertson, R. M. "Delayed excitatory connections in the flight system of the locust." Journal of Neurophysiology 65, no. 5 (May 1, 1991): 1150–57. http://dx.doi.org/10.1152/jn.1991.65.5.1150.
Full textAbstract:
1. Synaptic interactions between identified neurons in the flight system of the locust were investigated by the use of standard intracellular recording and staining techniques. The intent was to determine the distribution and functional significance of delayed excitatory connections, which have been previously described. 2. For one inhibitory connection it was demonstrated that subthreshold depolarization of the presynaptic neuron was sufficient to cause release of transmitter at the synapse. This established the existence of graded interactions between spiking flight neurons. 3. Three inhibitory interneurons were found to cause delayed excitatory responses in several other neurons. Often these were coupled with direct inhibitory connections between the same pre- and postsynaptic neurons, resulting in an inhibitory/excitatory (I/E) postsynaptic potential (PSP). The two phases of this PSP were variable. 4. Delayed excitatory connections appeared powerful while the flight system was inactive. However, these connections were disabled during flight rhythms at the phase when the presynaptic neuron was depolarized and firing action potentials. This was likely to be due to the nature of the disynaptic disinhibitory interaction being via (an) intervening neuron(s) with oscillating membrane potentials and thresholds for release of transmitter. 5. Thus connections demonstrated when flight rhythms were not expressed changed their character during flight rhythms. The delayed excitatory connections in this system probably reflect complex circuits of inhibition mediated by graded interactions and have little functional significance as phenomena in their own right.
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Tiesinga, Paul H. E. "Stimulus Competition by Inhibitory Interference." Neural Computation 17, no. 11 (November 1, 2005): 2421–53. http://dx.doi.org/10.1162/0899766054796905.
Full textAbstract:
When two stimuli are present in the receptive field of a V4 neuron, the firing rate response is between the weakest and strongest response elicited by each of the stimuli when presented alone (Reynolds, Chelazzi, & Desimone, 1999). When attention is directed toward the stimulus eliciting the strongest response (the preferred stimulus), the response to the pair is increased, whereas the response decreases when attention is directed to the other stimulus (the poor stimulus). When attention is directed to either of the two stimuli presented alone, the firing rate remains the same or increases slightly, but the coherence between the neuron's spike train and the local field potential can increase (Fries, Reynolds, Rorie, & Desimone, 2001). These experimental results were reproduced in a model of a V4 neuron under the assumption that attention modulates the activity of local interneuron networks. The V4 model neuron received stimulus-specific excitation from V2 and synchronous inhibitory inputs from two local interneuron networks in V4. Each interneuron network was driven by stimulus-specific excitatory inputs from V2 and was modulated by the activity of the frontal eye fields. Stimulus competition was present because of a delay in arrival time of synchronous volleys from each interneuron network. For small delays, the firing rate was close to the rate elicited by the preferred stimulus alone, whereas for larger delays, it approached the firing rate of the poor stimulus. When either stimulus was presented alone, the neuron's response was not altered by the change in delay, but could change due to modulation of the degree of synchrony of the corresponding interneuron network. The model suggests that top-down attention biases the competition between V2 columns for control of V4 neurons primarily by changing the relative timing of inhibition, whereas changes in the degree of synchrony of interneuron networks modulate the response to a single stimulus. The new mechanism proposed here for attentional modulation of firing rate, gain modulation by inhibitory interference, is likely to have more general applicability to cortical information processing.
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Lindsey, B. G., L. S. Segers, and R. Shannon. "Functional associations among simultaneously monitored lateral medullary respiratory neurons in the cat. II. Evidence for inhibitory actions of expiratory neurons." Journal of Neurophysiology 57, no. 4 (April 1, 1987): 1101–17. http://dx.doi.org/10.1152/jn.1987.57.4.1101.
Full textAbstract:
Arrays of extracellular electrodes were used to monitor simultaneously several (2-8) respiratory neurons in the lateral medulla of anesthetized, paralyzed, bilaterally vagotomized, artificially ventilated cats. Efferent phrenic nerve activity was also recorded. The average discharge rate as a function of time in the respiratory cycle was determined for each neuron. Most cells were tested for spinal or vagal axonal projections using antidromic stimulation methods. Cross-correlational methods were used to analyze spike trains of 480 cell pairs. Each pair included at least one neuron most active during the expiratory phase. All simultaneously recorded neurons were located in the same side of the brain stem. Twenty-six percent (33/129) of the expiratory (E) neuron pairs exhibited short time scale correlations indicative of paucisynaptic interactions or shared inputs, whereas 8% (27/351) of the pairs consisting of an E neuron and an inspiratory (I) cell were similarly correlated. Evidence for several inhibitory actions of E neurons was found: 1) inhibition of I neurons by E neurons with both decrementing (DEC) and augmenting (AUG) firing patterns; 2) inhibition of E-DEC and E-AUG neurons by E-DEC cells; 3) inhibition of E-DEC and E-AUG neurons by E-AUG neurons; and 4) inhibition of E-DEC neurons by tonic I-E phase-spanning cells. Because several cells were recorded simultaneously, direct evidence for concurrent parallel and serial inhibitory processes was also obtained. The results suggest and support several hypotheses for mechanisms that may help to generate and control the pattern and coordination of respiratory motoneuron activities.
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Tunstall, Mark J., Dorothy E. Oorschot, Annabel Kean, and Jeffery R. Wickens. "Inhibitory Interactions Between Spiny Projection Neurons in the Rat Striatum." Journal of Neurophysiology 88, no. 3 (September 1, 2002): 1263–69. http://dx.doi.org/10.1152/jn.2002.88.3.1263.
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The spiny projection neurons are by far the most numerous type of striatal neuron. In addition to being the principal projection neurons of the striatum, the spiny projection neurons also have an extensive network of local axon collaterals by which they make synaptic connections with other striatal projection neurons. However, up to now there has been no direct physiological evidence for functional inhibitory interactions between spiny projection neurons. Here we present new evidence that striatal projection neurons are interconnected by functional inhibitory synapses. To examine the physiological properties of unitary inhibitory postsynaptic potentials (IPSPs), dual intracellular recordings were made from pairs of spiny projection neurons in brain slices of adult rat striatum. Synaptic interactions were found in 9 of 45 pairs of neurons using averages of 200 traces that were triggered by a single presynaptic action potential. In all cases, synaptic interactions were unidirectional, and no bidirectional interactions were detected. Unitary IPSPs evoked by a single presynaptic action potential had a peak amplitude ranging from 157 to 319 μV in different connections (mean: 277 ± 46 μV, n = 9). The percentage of failures of single action potentials to evoke a unitary IPSP was estimated and ranged from 9 to 63% (mean: 38 ± 14%, n = 9). Unitary IPSPs were reversibly blocked by bicuculline ( n = 4) and had a reversal potential of −62.4 ± 0.7 mV ( n = 5), consistent with GABA-mediated inhibition. The findings of the present study correlate very well with anatomical evidence for local synaptic connectivity between spiny projection neurons and suggest that lateral inhibition plays a significant role in the information processing operations of the striatum.
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Lewis, David A., Takanori Hashimoto, and David W. Volk. "Cortical inhibitory neurons and schizophrenia." Nature Reviews Neuroscience 6, no. 4 (April 2005): 312–24. http://dx.doi.org/10.1038/nrn1648.
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Li, Guangnan, and Samuel J. Pleasure. "Exciting Information for Inhibitory Neurons." Neuron 69, no. 4 (February 2011): 585–87. http://dx.doi.org/10.1016/j.neuron.2011.02.011.
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Müller, Thomas H., D. Swandulla, and H. U. Zeilhofer. "Synaptic Connectivity in Cultured Hypothalamic Neuronal Networks." Journal of Neurophysiology 77, no. 6 (June 1, 1997): 3218–25. http://dx.doi.org/10.1152/jn.1997.77.6.3218.
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Müller, Thomas H., D. Swandulla, and H. U. Zeilhofer. Synaptic connectivity in cultured hypothalamic neuronal networks. J. Neurophysiol. 77: 3218–3225, 1997. We have developed a novel approach to analyze the synaptic connectivity of spontaneously active networks of hypothalamic neurons in culture. Synaptic connections were identified by recording simultaneously from pairs of neurons using the whole cell configuration of the patch-clamp technique and testing for evoked postsynaptic current responses to electrical stimulation of one of the neurons. Excitatory and inhibitory responses were distinguished on the basis of their voltage and time dependence. The distribution of latencies between presynaptic stimulation and postsynaptic response showed multiple peaks at regular intervals, suggesting that responses via both monosynaptic and polysynaptic paths were recorded. The probability that an excitatory event is transmitted to another excitatory neuron and results in an above-threshold stimulation was found to be only one in three to four. This low value indicates that in addition to evoked synaptic responses other sources of excitatory drive must contribute to the spontaneous activity observed in these networks. The various types of synaptic connections (excitatory and inhibitory, monosynaptic, and polysynaptic) were counted, and the observations analyzed using a probabilistic model of the network structure. This analysis provides estimates for the ratio of inhibitory to excitatory neurons in the network (1:1.5) and for the ratio of postsynaptic cells receiving input from a single GABAergic or glutamatergic neuron (3:1). The total number of inhibitory synaptic connections was twice that of excitatory connections. Cell pairs mutually connected by an excitatory and an inhibitory synapse occurred significantly more often than predicted by a random process. These results suggests that the formation of neuronal networks in vitro is controlled by cellular mechanisms that favor inhibitory connections in general and specifically enhance the formation of reciprocal connections between pairs of excitatory and inhibitory neurons. These mechanisms may contribute to network formation and function in vivo.
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Kwegyir-Afful, E. E., H. T. Kyriazi, and D. J. Simons. "Weaker feedforward inhibition accounts for less pronounced thalamocortical response transformation in mouse vs. rat barrels." Journal of Neurophysiology 110, no. 10 (November 15, 2013): 2378–92. http://dx.doi.org/10.1152/jn.00574.2012.
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Feedforward inhibition is a common motif of thalamocortical circuits. Strong engagement of inhibitory neurons by thalamic inputs enhances response differentials between preferred and nonpreferred stimuli. In rat whisker-barrel cortex, robustly driven inhibitory barrel neurons establish a brief epoch during which synchronous or near-synchronous thalamic firing produces larger responses to preferred stimuli, such as high-velocity deflections of the principal whisker in a preferred direction. Present experiments in mice show that barrel neuron responses to preferred vs. nonpreferred stimuli differ less than in rats. In addition, fast-spike units, thought to be inhibitory barrel neurons, fire less robustly to whisker stimuli in mice than in rats. Analyses of real and simulated data indicate that mouse barrel circuitry integrates thalamic inputs over a broad temporal window, and that, as a consequence, responses of barrel neurons are largely similar to those of thalamic neurons. Results are consistent with weaker feedforward inhibition in mouse barrels. Differences in thalamocortical circuitry between mice and rats may reflect mechanical properties of the whiskers themselves.
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Zhou, Fu-Ming, and John J. Hablitz. "Dopamine Modulation of Membrane and Synaptic Properties of Interneurons in Rat Cerebral Cortex." Journal of Neurophysiology 81, no. 3 (March 1, 1999): 967–76. http://dx.doi.org/10.1152/jn.1999.81.3.967.
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Dopamine modulation of membrane and synaptic properties of interneurons in rat cerebral cortex. Dopamine (DA) is an endogenous neuromodulator in the mammalian brain. However, it is still controversial how DA modulates excitability and input–output relations in cortical neurons. It was suggested that DA innervation of dendritic spines regulates glutamatergic inputs to pyramidal neurons, but no experiments were done to test this idea. By recording individual neurons under direct visualization we found that DA enhances inhibitory neuron excitability but decreases pyramidal cell excitability, through depolarization and hyperpolarization, respectively. Accordingly, DA also increased the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs). In the presence of TTX, DA did not affect the frequency, amplitude, or kinetics of miniature IPSCs and excitatory postsynaptic currents in inhibitory interneurons or pyramidal cells. Our results suggest that DA can directly excite cortical interneurons, but there is no detectable DA gate to regulate spontaneous GABA and glutamate release or the properties of postsynaptic GABA and glutamate receptors in neocortical neurons.
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Suwabe, Takeshi, Hideyuki Fukami, and Robert M. Bradley. "Synaptic Responses of Neurons Controlling the Parotid and von Ebner Salivary Glands in Rats to Stimulation of the Solitary Nucleus and Tract." Journal of Neurophysiology 99, no. 3 (March 2008): 1267–73. http://dx.doi.org/10.1152/jn.01115.2007.
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Salivary secretion results from reflex stimulation of autonomic neurons via afferent sensory information relayed to neurons in the rostral nucleus of the solitary tract (rNST), which synapse with autonomic neurons of the salivatory nuclei. We investigated the synaptic properties of the afferent sensory connection to neurons in the inferior salivatory nucleus (ISN) controlling the parotid and von Ebner salivary glands. Mean synaptic latency recorded from parotid gland neurons was significantly shorter than von Ebner gland neurons. Superfusion of GABA and glycine resulted in a concentration-dependent membrane hyperpolarization. Use of glutamate receptor antagonists indicated that both AMPA and N-methyl-d-aspartate (NMDA) receptors are involved in the evoked excitatory postsynaptic potentials (EPSPs). Inhibitory postsynaptic potential (IPSP) amplitude increased with higher intensity ST stimulation. Addition of the glycine antagonist strychnine did not affect the amplitude of the IPSPs significantly. The GABAA receptor antagonist, bicuculline (BMI) or mixture of strychnine and BMI abolished the IPSPs in all neurons. IPSP latency was longer than EPSP latency, suggesting that more than one synapse is involved in the inhibitory pathway. Results show that ISN neurons receive both excitatory and inhibitory afferent input mediated by glutamate and GABA respectively. The ISN neuron response to glycine probably derives from descending connections. Difference in the synaptic characteristics of ISN neurons controlling the parotid and von Ebner glands may relate to the different function of these two glands.
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Segers, L. S., R. Shannon, S. Saporta, and B. G. Lindsey. "Functional associations among simultaneously monitored lateral medullary respiratory neurons in the cat. I. Evidence for excitatory and inhibitory actions of inspiratory neurons." Journal of Neurophysiology 57, no. 4 (April 1, 1987): 1078–100. http://dx.doi.org/10.1152/jn.1987.57.4.1078.
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Data were obtained from 45 anesthetized (Dial), paralyzed, artificially ventilated, bilaterally vagotomized cats. Arrays of extracellular electrodes were used to monitor simultaneously the activities of lateral medullary respiratory neurons located in the rostral and caudal regions of the ventral respiratory group. The average discharge rate as a function of time in the respiratory cycle was determined for each neuron and concurrent phrenic nerve activity. Most cells were tested for axonal projections to the spinal cord or the ipsilateral vagus nerve using antidromic stimulation techniques. Seven hundred and sixty-one pairs of ipsilateral respiratory neurons that contained at least one neuron whose maximum discharge rate occurred during the inspiratory phase were analyzed by cross-correlation of the simultaneously recorded spike trains. Twenty-three percent of the 410 pairs of inspiratory (I) neurons showed short time scale correlations indicative of functional association due to paucisynaptic connections or shared inputs. Eight per cent of the 351 pairs composed of an I cell and and expiratory (E) neuron were correlated. We found evidence for excitation of both bulbospinal I neurons and I cells that were not antidromically activated by stimulation of the spinal cord and vagus nerve (NAA neurons) by NAA I cells. We also obtained data suggesting inhibitory actions of cells whose maximum discharge rate occurred in the first half of the I phase (I-DEC neurons). These actions included inhibition of other I-DEC neurons, inhibition of cells whose greatest firing rate occurred in the last half of the I phase (I-AUG neurons), inhibition of E-DEC neurons, and inhibition of E-AUG cells. Sixty-two percent (31/50) of the correlations that could be interpreted as evidence for an excitatory or inhibitory paucisynaptic connection were detected in pairs composed of a caudal and a rostral ventral respiratory group neuron. Eighty-eight percent (14/16) of proposed intergroup excitatory connections involved a projection from the rostral neuron of the pair to the caudal cell, whereas 73% (11/15) of proposed inhibitory connections involved a caudal-to-rostral projection. These results support and suggest several hypotheses for mechanisms that may help to control the development of augmenting activity in and the timing of each phase of the respiratory cycle.
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Wang, Jun, Jie Li, Qian Yang, Ya-Kai Xie, Ya-Lan Wen, Zhen-Zhong Xu, Yulong Li, et al. "Basal forebrain mediates prosocial behavior via disinhibition of midbrain dopamine neurons." Proceedings of the National Academy of Sciences 118, no. 7 (February 9, 2021): e2019295118. http://dx.doi.org/10.1073/pnas.2019295118.
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Sociability is fundamental for our daily life and is compromised in major neuropsychiatric disorders. However, the neuronal circuit mechanisms underlying prosocial behavior are still elusive. Here we identify a causal role of the basal forebrain (BF) in the control of prosocial behavior via inhibitory projections that disinhibit the midbrain ventral tegmental area (VTA) dopamine (DA) neurons. Specifically, BF somatostatin-positive (SST) inhibitory neurons were robustly activated during social interaction. Optogenetic inhibition of these neurons in BF or their axon terminals in the VTA largely abolished social preference. Electrophysiological examinations further revealed that SST neurons predominantly targeted VTA GABA neurons rather than DA neurons. Consistently, optical inhibition of SST neuron axon terminals in the VTA decreased DA release in the nucleus accumbens during social interaction, confirming a disinhibitory action. These data reveal a previously unappreciated function of the BF in prosocial behavior through a disinhibitory circuitry connected to the brain’s reward system.
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Sutter, M. L., and C. E. Schreiner. "Physiology and topography of neurons with multipeaked tuning curves in cat primary auditory cortex." Journal of Neurophysiology 65, no. 5 (May 1, 1991): 1207–26. http://dx.doi.org/10.1152/jn.1991.65.5.1207.
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1. The physiology and topography of single neuron responses along the isofrequency domain of the middle- and high-frequency portions [characteristic frequencies (CFs) greater than 4 kHz] of the primary auditory cortex (AI) were investigated in the barbiturate-anesthetized cat. Single neurons were recorded at several locations along the extent of isofrequency contours, defined from initial multiple-unit mapping. For each neuron a high-resolution excitatory tuning curve was determined, and for some neurons high-resolution two-tone tuning curves were recorded to measure inhibitory/suppressive areas. 2. A physiologically distinct population of neurons was found in the dorsal part of cat AI. These neurons exhibited two or three distinct excitatory frequency ranges, whereas most neurons in AI responded with excitation to a single narrow frequency range. These were called multipeaked neurons because of the shape of their tuning curves. At frequencies between the excitatory regions, the multipeaked neurons were inhibited or unresponsive. 3. Multipeaked neurons exhibited several distinct threshold minima in their frequency tuning curves. Most of the multipeaked neurons (88%) displayed two frequency minima, whereas the rest exhibited three minima. 4. The frequency separation between threshold minima was less than 1 octave in 71% of the double-peaked neurons recorded. Occasionally, the frequency peaks of these neurons closely corresponded to a response to second and third harmonics without a response to the fundamental frequency. 5. Multipeaked neurons exhibited a wide range of total bandwidths (highest excitatory frequency minus lowest excitatory frequency expressed in octaves). Bandwidths of the isolated peaks within the same neuron were also quite variable. 6. Response latencies to tones with frequencies within each peak of a multipeaked neuron could vary considerably. In 71% (17) of the neurons, tones corresponding to the high-frequency peak (CFh) elicited a longer response latency (greater than 4 ms) than those corresponding to the low-frequency peak (CF1). 7. Inhibitory/suppressive bands, as demonstrated with a two-tone paradigm, were often present between the peaks. Typically, neurons with excitatory peaks of similar response latencies showed an inhibitory band located between the peaks. 8. Ninety percent of the topographically localized multipeaked neurons were in the dorsal part of AI (greater than 1 mm dorsal to the maximum in the sharpness-of-tuning map). Although these neurons were restricted to dorsal AI, only 35% of neurons in this region were multipeaked. 9. Multipeaked neurons could show decreased response latencies and thresholds to two-tone combinations.(ABSTRACT TRUNCATED AT 400 WORDS)