Encoding of tactile stimulus location by somatosensory thalamocortical ensembles

Asif A. Ghazanfar, Christopher R. Stambaugh, Miguel A.L. Nicolelis

Research output: Contribution to journalArticlepeer-review

103 Scopus citations


The exquisite modular anatomy of the rat somatosensory system makes it an excellent model to test the potential coding strategies used to discriminate the location of a tactile stimulus. Here, we investigated how ensembles of simultaneously recorded single neurons in layer V of primary somatosensory (SI) cortex and in the ventral posterior medial (VPM) nucleus of the thalamus of the anesthetized rat may encode the location of a single whisker stimulus on a single trial basis. An artificial neural network based on a learning vector quantization algorithm, was used to identify putative coding mechanisms. Our data suggest that these neural ensembles may rely on a distributed coding scheme to represent the location of single whisker stimuli. Within this scheme, the temporal modulation of neural ensemble firing rate, as well as the temporal interactions between neurons, contributed significantly to the representation of stimulus location. The relative contribution of these temporal codes increased with the number of whiskers that the ensembles must discriminate among. Our results also indicated that the SI cortex and the VPM nucleus may function as a single entity to encode stimulus location. Overall, our data suggest that the representation of somatosensory features in the rat trigeminal system may arise from the interactions of neurons within and between the SI cortex and VPM nucleus. Furthermore, multiple coding strategies may be used simultaneously to represent the location of tactile stimuli.

Original languageEnglish (US)
Pages (from-to)3761-3775
Number of pages15
JournalJournal of Neuroscience
Issue number10
StatePublished - May 15 2000
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Neuroscience


  • Barrel cortex
  • Multi-electrode
  • Population coding
  • Primary somatosensory cortex
  • Temporal code
  • Ventral posterior medial nucleus


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