Visualization of a fibrillar organization in the synaptic cleft at cerebellar excitatory synapses by rapid-freeze, freeze-substitution and deep-etching electron microscopy

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OF MORPHINE DORSAL ROOT

TOSHIO SUZUKI and Chiba University, The

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ON THE SPINO-BULBO-SPINAL IN D E C E R E B R A T E CATS.

SATOSHI MURAYAMA, Department of 1-8-1 Inohana, Chiba 280, Japan with

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THE LOCUS CAERULEUS NEURON AND MOTOR SET

KEN-ICHI YAMAMOTO AND NOBUYUKI OZAWA* PSYCHIATRIC RESEARCH INSTITUTE OF TOKYO, 2-I-8 KAMIKITAZAWA, SETAGAYA-KU, TOKYO, 156 The locus caeruleus noradrenergic neuron ( LC-neuron ) was found to increase its firing rate reliably with an operantly conditioned task performance. Three Fischer strain rats were trained on a reaction-time task with warning, e.g. they were required to press a lever as soon as possible in response to an ~mperative stimulus ( $2, 2KHz tone ) preceded By 1.5sec by a warning stimulus ( SI, IKNz tone 0.]sec ). The unit activity of the LC-neuron was recorded during the task performance. Identification of the LC-neuron depended upon the presence of antidromic response to the electrical stimulation of the dorsal pathway chronically implanted electrode. Every unit activity of about 60 LC-neurons thus identified showed marked increases in association with the warning stimulus and stopped abruptly with the response of lever pressing. Neither mere tone stimulation ( SI, $2 ) without lever pressing response nor lever pressing during an intertrial interval was accompanied by the change of the LC-neural activity. The increase of LC firing rate was more intense when the reaction time was short ( 50-200msec ) than when ~t was long ( more than 400msec ). This finding is consistent with the view that the LC-neuron is re]ated to viRilance.