Activation of the primary motor cortex by somatosensory stimulation in adult rats is mediated mainly by associational connections from the somatosensory cortex

T. Farkas, Z. Kis, J. Toldi, J. R. Wolff

Research output: Contribution to journalArticle

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Abstract

In anaesthetized adult rats, facial nerve injury causes a disinhibition of the interhemispheric connections between homotopic representation fields in the primary motor cortex with a latency of 4 min (Toldi et al., 1996, Neurosci. Lett. 203, 179-182). One possible explanation for the induction of such rapid changes is an alteration of the somatosensory input to the motor cortex. To test this hypothesis, unit activity in primary motor cortex was recorded during electrical stimulation of trigeminal afferents in the contralateral whisker-pad. About one-third of all recorded primary motor cortex neurons responded with latencies shorter than in the ventrolateral and posterior nuclei of the thalamus. Responses failed at stimulation frequencies ≥10 Hz and after elimination or inactivation of the somatosensory cortex. Within primary motor cortex, the activatable neurons displayed a bilaminar distribution and were identified as pyramidal neurons by neurobiotin labelling. The results suggest that trigeminal afferents participate in modulation of the activity of primary motor cortex output neurons via primary somatosensory cortex-to-primary motor cortex associational connections, even under anaesthesia.

Original languageEnglish
Pages (from-to)353-361
Number of pages9
JournalNeuroscience
Volume90
Issue number2
DOIs
Publication statusPublished - Feb 22 1999

Fingerprint

Somatosensory Cortex
Motor Cortex
Posterior Thalamic Nuclei
Facial Nerve Injuries
Neurons
Vibrissae
Pyramidal Cells
Motor Neurons
Electric Stimulation
Anesthesia

Keywords

  • Associational connections
  • Motor cortex
  • Neurobiotin
  • Somatosensory cortex
  • Unit activity
  • Whisker-pad stimulation

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

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abstract = "In anaesthetized adult rats, facial nerve injury causes a disinhibition of the interhemispheric connections between homotopic representation fields in the primary motor cortex with a latency of 4 min (Toldi et al., 1996, Neurosci. Lett. 203, 179-182). One possible explanation for the induction of such rapid changes is an alteration of the somatosensory input to the motor cortex. To test this hypothesis, unit activity in primary motor cortex was recorded during electrical stimulation of trigeminal afferents in the contralateral whisker-pad. About one-third of all recorded primary motor cortex neurons responded with latencies shorter than in the ventrolateral and posterior nuclei of the thalamus. Responses failed at stimulation frequencies ≥10 Hz and after elimination or inactivation of the somatosensory cortex. Within primary motor cortex, the activatable neurons displayed a bilaminar distribution and were identified as pyramidal neurons by neurobiotin labelling. The results suggest that trigeminal afferents participate in modulation of the activity of primary motor cortex output neurons via primary somatosensory cortex-to-primary motor cortex associational connections, even under anaesthesia.",
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AU - Toldi, J.

AU - Wolff, J. R.

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