scholarly journals Ventral Posterior Medial Nucleus

2017 ◽  
pp. 1-1
Author(s):  
John E. Mendoza
Keyword(s):  
Medial Nucleus ◽  
Posterior Medial Nucleus

scholarly journals Responses of thalamic neurons to itch- and pain-producing stimuli in rats

2018 ◽  
Vol 120 (3) ◽  
pp. 1119-1134 ◽  
Author(s):  
Brett Lipshetz ◽  
Sergey G. Khasabov ◽  
Hai Truong ◽  
Theoden I. Netoff ◽  
Donald A. Simone ◽  
...  
Keyword(s):  
Single Unit ◽  
Electrophysiological Study ◽  
Receptive Fields ◽  
The Body ◽  
Cell Column ◽  
Thalamic Neurons ◽  
Medial Nucleus ◽  
Anesthetized Rats ◽  
Transmission Of Information ◽  
Posterior Medial Nucleus

Understanding of processing and transmission of information related to itch and pain in the thalamus is incomplete. In fact, no single unit studies of pruriceptive transmission in the thalamus have yet appeared. In urethane-anesthetized rats, we examined responses of 66 thalamic neurons to itch- and pain- inducing stimuli including chloroquine, serotonin, β-alanine, histamine, and capsaicin. Eighty percent of all cells were activated by intradermal injections of one or more pruritogens. Forty percent of tested neurons responded to injection of three, four, or even five agents. Almost half of the examined neurons had mechanically defined receptive fields that extended onto distant areas of the body. Pruriceptive neurons were located within what appeared to be a continuous cell column extending from the posterior triangular nucleus (PoT) caudally to the ventral posterior medial nucleus (VPM) rostrally. All neurons tested within PoT were found to be pruriceptive. In addition, neurons in this nucleus responded at higher frequencies than did those in VPM, an indication that PoT might prove to be a particularly interesting region for additional studies of itch transmission. NEW & NOTEWORTHY Processing of information related to itch within in the thalamus is not well understood, We show in this, the first single-unit electrophysiological study of responses of thalamic neurons to pruritogens, that itch-responsive neurons are concentrated in two nuclei within the rat thalamus, the posterior triangular, and the ventral posterior medial nuclei.

scholarly journals Encoding of Stimulus Frequency and Sensor Motion in the Posterior Medial Thalamic Nucleus

2008 ◽  
Vol 100 (2) ◽  
pp. 681-689 ◽  
Author(s):  
Radi Masri ◽  
Tatiana Bezdudnaya ◽  
Jason C. Trageser ◽  
Asaf Keller
Keyword(s):  
Barrel Cortex ◽  
Stimulus Frequency ◽  
Response Duration ◽  
Stimulation Frequency ◽  
Response Latencies ◽  
Medial Nucleus ◽  
Anesthetized Rats ◽  
Reticular Activating System ◽  
Parallel Streams ◽  
Posterior Medial Nucleus

In all sensory systems, information is processed along several parallel streams. In the vibrissa-to-barrel cortex system, these include the lemniscal system and the lesser-known paralemniscal system. The posterior medial nucleus (POm) is the thalamic structure associated with the latter pathway. Previous studies suggested that POm response latencies are positively correlated with stimulation frequency and negatively correlated with response duration, providing a basis for a phase locked loop-temporal decoding of stimulus frequency. We tested this hypothesis by analyzing response latencies of POm neurons, in both awake and anesthetized rats, to vibrissae deflections at frequencies between 0.3 and 11 Hz. We found no significant, systematic correlation between stimulation frequency and the latency or duration of POm responses. We obtained similar findings from recording in awake rats, in rats under different anesthetics, and in anesthetized rats in which the reticular activating system was stimulated. These findings suggest that stimulus frequency is not reliably reflected in response latency of POm neurons. We also tested the hypothesis that POm neurons respond preferentially to sensor motion, that is, they respond to whisking in air, without contacts. We recorded from awake, head-restrained rats while monitoring vibrissae movements. All POm neurons responded to passive whisker deflections, but none responded to noncontact whisking. Thus like their counterparts in the trigeminal ganglion, POm neurons may not reliably encode whisking kinematics. These observations suggest that POm neurons might not faithfully encode vibrissae inputs to provide reliable information on vibrissae movements or contacts.

scholarly journals Integration of signals from different cortical areas in higher order thalamic neurons

2021 ◽  
Vol 118 (30) ◽  
pp. e2104137118
Author(s):  
Vandana Sampathkumar ◽  
Andrew Miller-Hansen ◽  
S. Murray Sherman ◽  
Narayanan Kasthuri
Keyword(s):  
Higher Order ◽  
Cortical Layer ◽  
Thalamic Neurons ◽  
Cortical Areas ◽  
Medial Nucleus ◽  
Afferent Information ◽  
Posterior Medial Nucleus ◽  
Depth And Complexity ◽  
Genetic Labeling

Higher order thalamic neurons receive driving inputs from cortical layer 5 and project back to the cortex, reflecting a transthalamic route for corticocortical communication. To determine whether or not individual neurons integrate signals from different cortical populations, we combined electron microscopy “connectomics” in mice with genetic labeling to disambiguate layer 5 synapses from somatosensory and motor cortices to the higher order thalamic posterior medial nucleus. A significant convergence of these inputs was found on 19 of 33 reconstructed thalamic cells, and as a population, the layer 5 synapses were larger and located more proximally on dendrites than were unlabeled synapses. Thus, many or most of these thalamic neurons do not simply relay afferent information but instead integrate signals as disparate in this case as those emanating from sensory and motor cortices. These findings add further depth and complexity to the role of the higher order thalamus in overall cortical functioning.

scholarly journals Target-specific M1 inputs to infragranular S1 pyramidal neurons

2016 ◽  
Vol 116 (3) ◽  
pp. 1261-1274 ◽  
Author(s):  
Amanda K. Kinnischtzke ◽  
Erika E. Fanselow ◽  
Daniel J. Simons
Keyword(s):  
Primary Motor Cortex ◽  
Pyramidal Neurons ◽  
Projection Neurons ◽  
Cell Type ◽  
Intrinsic Properties ◽  
Subcortical Structures ◽  
Medial Nucleus ◽  
Cell Type Specific ◽  
Posterior Medial Nucleus

The functional role of input from the primary motor cortex (M1) to primary somatosensory cortex (S1) is unclear; one key to understanding this pathway may lie in elucidating the cell-type specific microcircuits that connect S1 and M1. Recently, we discovered that a subset of pyramidal neurons in the infragranular layers of S1 receive especially strong input from M1 (Kinnischtzke AK, Simons DJ, Fanselow EE. Cereb Cortex 24: 2237–2248, 2014), suggesting that M1 may affect specific classes of pyramidal neurons differently. Here, using combined optogenetic and retrograde labeling approaches in the mouse, we examined the strengths of M1 inputs to five classes of infragranular S1 neurons categorized by their projections to particular cortical and subcortical targets. We found that the magnitude of M1 synaptic input to S1 pyramidal neurons varies greatly depending on the projection target of the postsynaptic neuron. Of the populations examined, M1-projecting corticocortical neurons in L6 received the strongest M1 inputs, whereas ventral posterior medial nucleus-projecting corticothalamic neurons, also located in L6, received the weakest. Each population also possessed distinct intrinsic properties. The results suggest that M1 differentially engages specific classes of S1 projection neurons, thereby regulating the motor-related influence S1 exerts over subcortical structures.

scholarly journals High-order thalamic inputs to primary somatosensory cortex are stronger and longer lasting than cortical inputs

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Wanying Zhang ◽  
Randy M Bruno
Keyword(s):  
Somatosensory Cortex ◽  
Primary Motor Cortex ◽  
Pyramidal Neurons ◽  
Sensory Stimulation ◽  
Primary Somatosensory Cortex ◽  
Specific Substrate ◽  
Medial Nucleus ◽  
Posterior Medial Nucleus ◽  
Cortical Inputs

Layer (L) 2/3 pyramidal neurons in the primary somatosensory cortex (S1) are sparsely active, spontaneously and during sensory stimulation. Long-range inputs from higher areas may gate L2/3 activity. We investigated their in vivo impact by expressing channelrhodopsin in three main sources of feedback to rat S1: primary motor cortex, secondary somatosensory cortex, and secondary somatosensory thalamic nucleus (the posterior medial nucleus, POm). Inputs from cortical areas were relatively weak. POm, however, more robustly depolarized L2/3 cells and, when paired with peripheral stimulation, evoked action potentials. POm triggered not only a stronger fast-onset depolarization but also a delayed all-or-none persistent depolarization, lasting up to 1 s and exhibiting alpha/beta-range oscillations. Inactivating POm somata abolished persistent but not initial depolarization, indicating a recurrent circuit mechanism. We conclude that secondary thalamus can enhance L2/3 responsiveness over long periods. Such timescales could provide a potential modality-specific substrate for attention, working memory, and plasticity.

Active tactile exploration influences the functional maturation of the somatosensory system

1996 ◽  
Vol 75 (5) ◽  
pp. 2192-2196 ◽  
Author(s):  
M. A. Nicolelis ◽  
L. M. De Oliveira ◽  
R. C. Lin ◽  
J. K. Chapin
Keyword(s):  
Facial Nerve ◽  
Somatosensory System ◽  
Tactile Perception ◽  
Sensory Innervation ◽  
Medial Nucleus ◽  
Functional Maturation ◽  
Body Regions ◽  
The Face ◽  
Posterior Medial Nucleus ◽  
Active Exploration

1. The hypothesis that active exploration of objects is required for the functional maturation of neuronal circuits subserving tactile perception was tested by subjecting 8- to 11-day old rats to a complete unilateral section of the facial nerve. This procedure selectively abolished whisker protraction movements without affecting the sensory innervation of the facial vibrissae, the tactile organs used by rats to discriminate object texture and shape. 2. Six to 14 mo after the facial nerve section, simultaneous recordings of neuronal ensembles located in the ventral posterior medial nucleus (VPM) of the thalamus revealed a marked reduction in receptive field (RF) size (in terms of number of whiskers), and the formation of abnormal RF surrounds, spanning the face and contiguous body regions. In addition, the directional organization of VPM RFs, represented by caudal to rostral shifts in RF centers over 30 ms following whisker stimulation, was greatly reduced in these animals. 3. These results suggest that neonatal active tactile exploration is required to establish normal spatiotemporal patterning of neuronal RFs within the somatosensory system, and consequently, to develop normal tactile perception.

scholarly journals Synaptic Properties of Thalamic Input to Layers 2/3 and 4 of Primary Somatosensory and Auditory Cortices

2011 ◽  
Vol 105 (1) ◽  
pp. 279-292 ◽  
Author(s):  
Angela N. Viaene ◽  
Iraklis Petrof ◽  
S. Murray Sherman
Keyword(s):  
Medial Geniculate Body ◽  
Postsynaptic Neuron ◽  
Paired Pulse ◽  
Response Characteristics ◽  
Medial Nucleus ◽  
Thalamic Stimulation ◽  
Thalamocortical Projections ◽  
Class 1 ◽  
Medial Geniculate ◽  
Posterior Medial Nucleus

We studied the synaptic profile of thalamic inputs to cells in layers 2/3 and 4 of primary somatosensory (S1) and auditory (A1) cortices using thalamocortical slices from mice age postnatal days 10–18. Stimulation of the ventral posterior medial nucleus (VPM) or ventral division of the medial geniculate body (MGBv) resulted in two distinct classes of responses. The response of all layer 4 cells and a minority of layers 2/3 cells to thalamic stimulation was Class 1, including paired-pulse depression, all-or-none responses, and the absence of a metabotropic component. On the other hand, the majority of neurons in layers 2/3 showed a markedly different, Class 2 response to thalamic stimulation: paired-pulse facilitation, graded responses, and a metabotropic component. The Class 1 and Class 2 response characteristics have been previously seen in inputs to thalamus and have been described as drivers and modulators, respectively. Driver input constitutes a main information bearing pathway and determines the receptive field properties of the postsynaptic neuron, whereas modulator input influences the response properties of the postsynaptic neuron but is not a primary information bearing input. Because these thalamocortical projections have comparable properties to the drivers and modulators in thalamus, we suggest that a driver/modulator distinction may also apply to thalamocortical projections. In addition, our data suggest that thalamus is likely to be more than just a simple relay of information and may be directly modulating cortex.

Differences in Response to Muscarinic Activation Between First and Higher Order Thalamic Relays

2007 ◽  
Vol 98 (6) ◽  
pp. 3538-3547 ◽  
Author(s):  
C. Varela ◽  
S. Murray Sherman
Keyword(s):  
Brain Slices ◽  
Medial Geniculate Body ◽  
Input Resistance ◽  
Higher Order ◽  
First Order ◽  
Medial Nucleus ◽  
Dorsal Portion ◽  
Medial Geniculate ◽  
Lateral Posterior ◽  
Posterior Medial Nucleus

The mammalian thalamus is composed of two types of thalamocortical relay. First order relays receive information from subcortical sources and relay it to cortex, whereas higher order relays receive information from layer 5 of one cortical area and relay it to another. Recent reports suggest that modulatory inputs to first and higher order relays may differ. We used rat thalamic brain slices and whole cell recordings from relay cells in various first order (the lateral geniculate nucleus, the ventral posterior nucleus, and the ventral portion of the medial geniculate body) and higher order (the lateral posterior, the posterior medial nucleus, and the dorsal portion of the medial geniculate body) relays to explore their responses to activation of muscarinic receptors. We found that, whereas all first order relay cells show a depolarizing response to muscarinic activation, ∼20% of higher order relay cells respond with hyperpolarization. The depolarization is accompanied by an overall increase in input resistance, whereas the hyperpolarization correlates with a decrease in resistance. Because activation of cholinergic brain stem afferents to thalamus increases with increasing behavioral vigilance, the findings suggest that increased vigilance will depolarize all first order and most higher order relay cells but will hyperpolarize a significant subset of higher order relay cells. Such hyperpolarization is expected to bias these relay cells to the burst firing mode, and so these results are consistent with evidence of more bursting among higher order than first order relay cells.

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