CORTEX conference by Mriganka Sur

The computational power of the cerebral cortex derives from its neuronal wiring. Neuronal circuits are the engine of the brain, for they transform simple inputs into complex outputs underlying behavior and cognition. Novel technologies are transforming our understanding of the development and function of cortical circuits. We have recently used high-resolution imaging of identified synapses on mouse visual cortex neurons in vivo to discover principles by which neighboring synapses co-operatively implement neuronal plasticity (El-Boustani et al., Science 2018). Such plasticity shapes cortical circuits for visual functions. Two-photon measurements of neuronal responses in the intact mouse brain combined with manipulations of activity have revealed unique functions of inhibitory circuits in response tuning and gain control (Wilson et al., Nature 2012; El-Boustani and Sur, Nature Communications 2014). Probing mechanisms of internal states, we have demonstrated a crucial role for cholinergic inputs to inhibitory-disinhibitory circuits in shaping the temporal dynamics of cortical activity during arousal and attention (Chen et al., Nature Neuroscience 2015). These discoveries demonstrate that cortical circuits contribute particular functions, and even ‘diffuse’ neurotransmitter systems act via cell-specific circuits to modulate cortical processing and brain states. Local and long-range circuits together mediate behavior: recent experiments in awake behaving mice, combining large scale imaging across multiple areas and optogenetic manipulation, have revealed principles of information flow from sensory through parietal to motor and prefrontal cortex in mice during goal-directed behavior (Goard et al., eLife 2016; Pho et al., Nature Communications 2018). The logic of these circuits reveals fundamental principles of information processing underlying sensorimotor transformations and lays the groundwork for rich experimental and computational analyses of normal and abnormal brain function (Banerjee et al., PNAS 2016).