Somatosensory rhythms in the awake cat: a single unit exploration of their thalamic concomitant in nucleus ventralis posterior and vicinity.
A microelectrode study was performed in n. ventralis posterior (VP) of the fully alert cat, to study the correlation between thalamic unit activity and the cortical synchronized 14 c/sec rhythms that develop in the somatic area I for forepaw and wrist projections, when the animal is in a state of "quiet waking". (i) Only a small proportion of VP cells underwent changes during the studied cortical rhythms. (ii) None of these cells were typical thalamo-cortical relay cells carrying tactile messages to the cortex. (iii) Cells altering their discharge were of two types, rhythmic (R) cells, discharging at the frequency of the cortical rhythms, and tonic (T) cells, displaying an overall, sustained change during the whole sequence of cortical 14 c/sec. (iv) Among R cells, some were long axon thalamo-cortical cells and others, likely to be interneurones. (v) Some T cells increased their firing rate during rhythmic trains, others came into silence during the same period. (vi) The thalamic circuitry responsible for this particular set of "quiet waking rhythms" is discussed.
D000200:Action Potentials; D000818:Animals; D002415:Cats; D003243:Consciousness; D009474:Neurons / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology*; D013788:Thalamus / Q000166:cytology / Q000502:physiology*