Brain meeting: Dr Chen Song

Structure shapes function. Understanding what kinds of brain structure are optimal for cognitive function is fundamental to neuroscience research as well as to the design of artificial intelligence. Traditionally, large brain volumes, large number of neurons and strong neural connections are considered beneficial. In this talk, I will present our experimental and theoretical work that challenges the conventional wisdom. We show that a functionally optimal visual cortex is constituted of a large cortical surface area, but a small cortical thickness and weak lateral connections. This architecture enables neurons in visual cortex to have high selectivity, short latency, and human participants to excel in visual tasks. To achieve the optimal brain structure, we show that sleep plays an essential role. Sleep facilitates the overnight improvement in cognitive function through homeostatic weakening of neural connections and thinning of cortex, at both a cellular and a system level. The overnight brain structural changes in turn enhance the cost-efficacy of brain activity. I will conclude by discussing how a balanced view of brain structure and function requires the consideration of sleep-wake cycle, and how the contrast between awake and sleeping brain activity may be key to our intelligence.