A Demonstration of Tonic Inhibitory and Facilitatory Striatal Actions on Substantia Nigra Neurons
The striatonigral pathway was first demonstrated from electrophysiological studies (Frigyesi and Purpura, 1967; Albe-Fessard et al., 1967) and it is now well accepted that neurons in this pathway contain GABA (Hattori et al., 1973) and have an inhibitory effect on substantia nigra neurons (Precht and Yoshida, 1971). Another component of the striatonigral pathway liberating substance P into the substantia nigra has been shown to exist from biochemical and anatomical studies, and seems to cause excitation of substantia nigra neurons (Davies and Dray, 1976; Kanazawa et al., 1977). In order to examine the functional effects of these two components of the striatonigral pathway the activity of substantia nigra neurons was studied during a brief excitation followed by a longer lasting blockade of striatal activity. This excitation/blockade was provoked by employing, in the striatum, the spreading depression technique first demonstrated in the cortex by Leao (1944).
KeywordsSubstantia Nigra Spreading Depression Striatal Cell Spontaneous Firing Rate Antidromic Activation
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