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Spatiotemporal structure of somatosensory responses of many-neuron ensembles in the rat ventral posterior medial nucleus of the thalamus.

Publication ,  Journal Article
Nicolelis, MA; Chapin, JK
Published in: J Neurosci
June 1994

Classically, the rat ventral posterior medial (VPM) nucleus of the thalamus has been considered as a simple passive relay for single-whisker information to the primary somatosensory cortex (SI). However, recent reports have suggested that the VPM could contain a much more coarsely coded and spatiotemporally complex representation of the rat whisker pad. To address this possibility properly, we have carried out chronic simultaneous recordings of large numbers (up to 23) of single neurons, distributed across the entire VPM, in both awake and lightly anesthetized adult rats. Quantitative, computer-based reconstruction of receptive fields (RFs) revealed that single VPM neurons exhibit significant responses to discrete stimulation of as many as 20 single whiskers (mean +/- SD RF size, 13.7 +/- 4.8 whiskers). By defining multiple response magnitude (RM) thresholds it was possible to subdivide these large VPM RFs quantitatively into a prominent center (mean +/- SD, 1.41 +/- 0.70 whiskers, RM > 95%) and an excitatory surround (up to 18 whiskers, RM < 95%). VPM neurons exhibited both short-latency responses (SLRs, from 4 to 10 msec poststimulus) and/or long-latency responses (LLRs, 15-25 msec), each followed by inhibitory responses. Though LLRs were weaker (mean +/- SD, 47.19 +/- 33.34 Hz) than SLRs (119.63 +/- 50.12 Hz), they often defined RFs that differed considerably from those defined by the SLRs of the same cell. In particular, VPM cells with short-latency RFs centered in caudal whiskers (e.g., C1, D1, E1) showed a poststimulus time-dependent shift of these RF centers toward the rostral whiskers (e.g., C4, D4, E4). These caudal-to-rostral (C-->RF shifts occurred in neurons with the largest RFs of our sample (17.2 +/- 2.4 whiskers). On the other hand, VPM cells with short-latency RFs centered in rostral whiskers had the smallest RFs (13.1 +/- 4.1 whiskers) and usually did not exhibit time-dependent RF center shifts. Multivariate analysis revealed that these two groups of VPM neurons, C-->R shifting and rostral position (RP) cells, could be statistically distinguished according to a combination of three RF attributes (short-latency RF center location, RF size, and magnitude of RF center shift). Quantitative, computer-based reconstruction of "population response maps" demonstrated that the "place" coding for each single whisker in the VPM involved a distinct weighted contribution from a large proportion of the simultaneously recorded neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

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Published In

J Neurosci

DOI

ISSN

0270-6474

Publication Date

June 1994

Volume

14

Issue

6

Start / End Page

3511 / 3532

Location

United States

Related Subject Headings

  • Wakefulness
  • Vibrissae
  • Thalamic Nuclei
  • Reaction Time
  • Rats, Inbred Strains
  • Rats
  • Physical Stimulation
  • Neurons
  • Neurology & Neurosurgery
  • Evoked Potentials, Somatosensory
 

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Nicolelis, M. A., & Chapin, J. K. (1994). Spatiotemporal structure of somatosensory responses of many-neuron ensembles in the rat ventral posterior medial nucleus of the thalamus. J Neurosci, 14(6), 3511–3532. https://doi.org/10.1523/JNEUROSCI.14-06-03511.1994
Nicolelis, M. A., and J. K. Chapin. “Spatiotemporal structure of somatosensory responses of many-neuron ensembles in the rat ventral posterior medial nucleus of the thalamus.J Neurosci 14, no. 6 (June 1994): 3511–32. https://doi.org/10.1523/JNEUROSCI.14-06-03511.1994.
Nicolelis, M. A., and J. K. Chapin. “Spatiotemporal structure of somatosensory responses of many-neuron ensembles in the rat ventral posterior medial nucleus of the thalamus.J Neurosci, vol. 14, no. 6, June 1994, pp. 3511–32. Pubmed, doi:10.1523/JNEUROSCI.14-06-03511.1994.

Published In

J Neurosci

DOI

ISSN

0270-6474

Publication Date

June 1994

Volume

14

Issue

6

Start / End Page

3511 / 3532

Location

United States

Related Subject Headings

  • Wakefulness
  • Vibrissae
  • Thalamic Nuclei
  • Reaction Time
  • Rats, Inbred Strains
  • Rats
  • Physical Stimulation
  • Neurons
  • Neurology & Neurosurgery
  • Evoked Potentials, Somatosensory