Contribution of amygdalar and lateral hypothalamic neurons to visual information processing of food and nonfood in monkey.
Visual information processing was investigated in the inferotemporal cortical (ITCx)-amygdalar (AM)-lateral hypothalamic (LHA) axis which contributes to food-nonfood discrimination. Neuronal activity was recorded from monkey AM and LHA during discrimination of sensory stimuli including sight of food or nonfood. The task had four phases: control, visual, bar press, and ingestion. Of 710 AM neurons tested, 220 (31.0%) responded during visual phase: 48 to only visual stimulation, 13 (1.9%) to visual plus oral sensory stimulation, 142 (20.0%) to multimodal stimulation and 17 (2.4%) to one affectively significant item. Of 669 LHA neurons tested, 106 (15.8%) responded in the visual phase. Of 80 visual-related neurons tested systematically, 33 (41.2%) responded selectively to the sight of any object predicting the availability of reward, and 47 (58.8%) responded nondifferentially to both food and nonfood. Many of AM neuron responses were graded according to the degree of affective significance of sensory stimuli (sensory-affective association), but responses of LHA food responsive neurons did not depend on the kind of reward indicated by the sensory stimuli (stimulus-reinforcement association). Some AM and LHA food responses were modulated by extinction or reversal. Dynamic information processing in ITCx-AM-LHA axis was investigated by reversible deficits of bilateral ITCx or AM by cooling. ITCx cooling suppressed discrimination by vision responding AM neurons (8/17). AM cooling suppressed LHA responses to food (9/22). We suggest deep AM-LHA involvement in food-nonfood discrimination based on AM sensory-affective association and LHA stimulus-reinforcement association.
Department of Physiology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan.
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T
Ono
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R
Tamura
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H
Nishijo
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K
Nakamura
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E
Tabuchi
D000339:Affect; D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001931:Brain Mapping; D003080:Cold Temperature; D003216:Conditioning, Operant; D004192:Discrimination, Psychological / Q000502:physiology*; D005502:Food; D007026:Hypothalamic Area, Lateral / Q000502:physiology*; D008251:Macaca; D009474:Neurons / Q000145:classification / Q000502:physiology; D012201:Reward; D014796:Visual Perception / Q000502:physiology*