Response of ventrobasal thalamic neurons activated by dorsal and dorsolateral funiculi: an intracellular study.

Intracellular responses to stimulation of the dorsal column (DC) and dorsolateral funiculus (DLF) were recorded in cells of the thalamic ventrobasal complex (VB) in anesthetized cats, with the dorsal funiculi either intact or isolated. The responsiveness of VB neurons was tested using graded stimulation, paired-shock, and interaction techniques. Of the 60 VB neurons thoroughly studied, 50 responded to stimulation of the DC with excitatory postsynaptic potentials (EPSPs) followed by inhibitory postsynaptic potentials (IPSPs); half of these 50 neurons responded to stimulation of the DLF with the same pattern, whereas no IPSPs could be elicited in the remaining neurons.

Intracellular study of presumed interneurons in the ventrobasal complex of cats with chronic cortical ablations.

In a ventrobasal neuronal population surviving chronic ablation of somatosensory and motor cortices, the input-output properties of cells activated by ML fibers and showing functional characteristics of interneurons (large peripheral receptive fields, convergence of different types of receptor afferents, repetitive discharge) were studied. Since intracellular recordings showed the presence of excitatory and inhibitory postsynaptic potentials, it is argued that inhibitory interneurons also receive inhibitory inputs, suggesting that data processing in VB is more complex than hitherto postulated.