The Effects of Drugs on the Field Potential in the Caudate Nucleus Following Nigra Stimulation
The reciprocal connections of the caudate (Cd) and nigra (Ni) nuclei have been extensively studied using anatomical 2, 17, 26, 27, 28, 35, 36, 37, histochemical 1, 13, 30, 8 and electrophysiological 3, 6, 9, 12, 14, 15, 22, 23, 24. 38 methods but in some respects the situation is even less satisfactory than a few years ago. The present communication is aimed at examining the characteristics of field potentials in the Cd evoked from stimulation of the Ni before and after systemic application of drugs. The cats were anaesthetized with sodium pentobarbital (30–40 mg/kg), immobilized by flaxedil and artifically ventilated. The overlying cortical structures were removed by suction to expose the dorsal surface of the Cd. The nigro-caudate pathway was electrically stimulated using bipolar electrodes placed in the Ni proper. Similar electrodes in the cerebral peduncle (CP) allowed antidromic activation of the Cd. Field potentials were recorded in the medial two thirds of the ipsilateral Cd with glass microelectrodes filled with either 2 M sodium chloride or 3 M potassium chloride (DC resistance: 3–5 MΩ). A Nicollete 1074 was used for averaging the signals. The recording and stimulating electrode tracts were identified histologically.
KeywordsSubstantia Nigra Field Potential Caudate Nucleus Corpus Striatum Positive Wave
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