The hypothalamus as a primary coordinator of memory updating

• Published in: Physiology & behavior Vol. 223; p. 112988
• Main Authors: Burdakov, Denis, Peleg-Raibstein, Daria
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.09.2020
• Subjects: amygdala; Anxiety; Arousal; Associative learning; cognition; cortex; cost benefit analysis; Fear; Food; hippocampus; Hypocretin; Hypothalamus; Learning; Melanin-concentrating hormone; Memory; motivation; Neuropeptides; Non-associative learning: Energy balance; Nutrients; Orexin; Punishment; Reinforcement; Reward; sleep; Punishment; Non-associative learning: Energy balance; Memory; Associative learning; Neuropeptides; Hypothalamus; Hypocretin; Learning; Fear; Melanin-concentrating hormone; Arousal; Reinforcement; Nutrients; Anxiety; Reward; Orexin; Food
• ISSN: 0031-9384; 1873-507X; 1873-507X
• DOI: 10.1016/j.physbeh.2020.112988

•Hypothalamic neurons are essential for diverse types of learning and memory•Neurotransmittters unique to hypothalamus modify synaptic strength in in vitro preprations, suggesting that hypothalamus can control memory without changing attention/motivation•The evolutionary advantages of hypothalamic influence on logic gates for memory updating need to be defined In the brain, long-term memories correspond to changes in synaptic weights after certain patterns of neural activity. Behaviourally, this corresponds to a change in action evoked by a repeating experience. Forming and updating memories (learning, remembering, forgetting) is fundamental for most aspects of cognitive and motor performance. The roles of the cortex, hippocampus, and amygdala have been studied extensively in this context. However, the lateral hypothalamus – a brain-wide projecting region traditionally known as a nutrient-sensor and controller of arousal and motivation – is also critical for updating many types of associative and non-associative memories. Does the hypothalamus play a primary role in learning, or are hypothalamic effects on learning secondary to changes in brain state such as attention/motivation? We argue that such primary and secondary effects are distinguishable under experimental conditions where attention/motivation states are constant or absent, e.g. during sleep or in reduced in vitro preparations. The documented control by hypothalamus-unique transmitters, such as orexin and MCH, of synaptic strength in isolated brain slice preparations implies a primary role for the hypothalamus in synaptic weight updating, rather than a secondary role due to changes in arousal/attention/motivation states (which are absent in brain slices). Such hypothalamic control of memory-related synaptic machinery may enable gating/thresholding/permissive/tagging operations within yet poorly defined logic gates for memory updating. Hypothalamic signals may thus facilitate cost-benefit analysis of learning and memory in real-world settings. Whether the hypothalamus controls only specific types of learning, or broadcasts a global signal for memory updating, remains to be elucidated.