[Electrophysiologic analysis of interaction between afferent inputs to the rat neostriatum]

The interaction of the efferent inputs of the caudate nucleus in the region of their maximal overlapping was studied by paired stimulation. The stimulation of the n. paracentralis and cortex resulted in an increased amplitude of the tested response. On the contrary, the tested responses to stimulation of substantia nigra (zona compacta) and n. raphe (dorsal region) were inhibited. The paired stimulation showed a particular hierarchy of different afferent inputs as to their mutual influence: frontal cortex--thalamic intralaminar nucleus--midbrain structures. The afferent inputs from higher levels, while molulating the activity of those from lower ones, do not reliably change their own activity under the action of the latter. Possible mechanisms of this modulation are discussed.