| Co-Investigator(Kenkyū-buntansha) |
EIFUKU Satoshi Toyama Medical and Parmaceutical University, Department of Physiology, Assistant, 医学部, 助手 (70262508)
TAMURA Ryoi Toyama Medical and Parmaceutical University, Department of Physiology, Assistant, 医学部, 助手 (60227296)
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| Research Abstract |
1. To investigate the role of the amygdala (AM), mediodorsal thalamic nucleus (MD), and anterior cingulate cortex (AC) in learning of emotional stimuli, neuronal activity in the AM,MD,and AC was recorded from the rats trained to discriminate conditioned sensory stimuli associated with and without reinforcements.
2. In the AM,neurons in the lateral and basolateral nuclei had unimodal and multimodal responsiveness, respectively, and neurons in the both nuclei responded differentially to conditioned stimuli based on reward contingency (differential conditioned stimulusrelated neurons). Furthermore, comparison of responsiveness to gustatory stimuli between neurons in the AM and pontine taste area indicated that the AM was involved in affective evaluation of gustatory stimuli.
3. In the MD,most neurons had multimodal responsiveness, and were differential conditioned stimulus-related neurons. These MD neurons were located mainly in the rostro-medial portion of the MD,which receives afferents f
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rom the basolateral nucleus of the AM,where various sensory information converges. The present results, along with previous anatomical studies, suggest the existence of limbic emotional circuits ; AM-medial MD-orbital prefrontal cortex (emotional memory).
4. In the AC,differential conditioned stimulus-related neurons were located mainly in the rostral and ventral part of the anterior cingulate cortex. The other type of neurons responded mainly during ICSS and/or ingestion of sucrose (ingestion/ICSS-related neurons). Activity of the ingestion/ICSS-related neurons was correlated to the 1st lick to obtain rewards during the task, suggesting that the activity reflected some aspects of motor functions for learned instrumental behaviors. These ingestion/ICSS-related neurons were located sparsely in the caudal and dorsal part of the anterior cingulate cortex. The results suggest that the anterior cingulate cortex is topographically organized ; stimulus attributes predicting reward or no reward are represented in a rostral and ventral part of the anterior cingulate cortex, while a caudal and dorsal part of the anterior cingulate cortex is related to execution of learned instrumental behaviors. Less
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