| Co-Investigator(Kenkyū-buntansha) |
EIFUKU Satoshi Toyama Medical and Pharmaceutical University, Faculty of Medicine, Assistant Professor, 医学部, 助手 (70262508)
TAMURA Ryoi Toyama Medical and Pharmaceutical University, Faculty of Medicine, Associate Professor, 医学部, 助教授 (60227296)
NISHIJO Hisao Toyama Medical and Pharmaceutical University, Faculty of Medicine, Professor, 医学部, 教授 (00189284)
UWANO Teruko Toyama Medical and Pharmaceutical University, Faculty of Medicine, Assistant Professor, 医学部, 助手 (80242486)
AIBA Atsushi Tokyo University, Faculty of Medicine, Associate Professor, 医科学研究所, 助教授 (20271116)
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| Research Abstract |
1.Neural mechanisms of emotion in the limbic system
Neuronal activity in the anterior cingulate cortex (AC), amygdala (AM), and posterior thalamus (PT) of rats was recorded during discrimination of conditioned sensory stimuli associated with and without reward aiid aversion. In the AC, differential conditioned stimulus-related neurons were located mainly in the rostral and ventral part of the AC. The other AC neurons responded mainly during ICSS and/or ingestion of sucrose (ingestion/ICSS-related neurons), and were located in a more posterior part of the AC. In the AM, most neurons had multimodal responsiveness, and were differential to the conditioned stimuli. These AM neurons were located mainly in the basolateral nucleus of the AM. The PT (nonprimary thalamic) neurons displayed 2 types of responses; the early phasic responses dependent on the sensory modality, and the late responses that gradually increased, and peaked just prior to reward delivery. The results suggest that single th
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alamic neurons can code for the acquired significance of sensory stimuli in the early responses (retrospective coding) and predict upcoming reward value in the late responses (prospective coding).
2. Neural mechanisms of spatial navigation
Nneuronal activity was recorded from the lateral septal nuclei, hippocampal formation (HP), and nucleus of accumbens (NAC) of monkeys, rats, and mice while animals freely navigated in the experimental field to acquire reward. The results suggest that; 1) the lateral septal nuclei are involved in integration of space, inertial sensation and reward, 2) although activity in both the HF and NAC was correlated with spatial parameters, the NAC neurons were more likely to respond to reward, while the firing of the HF neurons was more closely tied to spatial parameters, 3) some pairs of HF neurons displayed task-dependent place fields where activity increased in specific area in the experimental field, and task-dependent cross-correlation.
3. Neural mechanisms of recognition of a face
More than 80 faces-responsive neurons were recorded from the anterior part of the monkey superior temporal sulcus (STS). The results show that; 1) many face-responsive neurons were tuned to 45-degree (or 3/4) views not only to frontal views and profiles, 2) some of the 45-degree-optimal neurons showed mirror-image response to the opposite 45-degree view, 3) 45-degree-optimal response were often synergistically enhanced by eye-contact gaze. The results suggest interactions of face and gaze directions in the neuronal responses of the anterior STS.
4. Molecular and genetic bases of the limbic system
1) D2 receptor knockout (D2R-KO) mice displayed increased anxiety and blunted circadian rhythms as well as reduced locomotor activity and slower acquisition of a place learning task. 2) D2R-KO eliminated the pre-reward anticipatory responses, and increased number of place-related activity of the NAC neurons, suggesting that the NAC D2R participates in coding for a specific type of neuronal response to incentive contingencies and partly in spatial learning. 3) ACh and vasopressin analogs ameliorated learning deficits of rats with hippocampal lesions. Less
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