Neural control of brain state

• Forebrain activity is characterized by rapid transitions between multiple states.
• Brain state is controlled on multiple spatial and temporal scales.
• Brain state strongly influences sensory responses and behavioral decisions.
• Glutamatergic feedback and feedforward pathways rapidly control local network state.
• Brain state can change the gain, reliability, precision, or synchronization of neural responses.

How the brain takes in information, makes a decision, and acts on this decision is strongly influenced by the ongoing and constant fluctuations of state. Understanding the nature of these brain states and how they are controlled is critical to making sense of how the nervous system operates, both normally and abnormally. While broadly projecting neuromodulatory systems acting through metabotropic pathways have long been appreciated to be critical for determining brain state, more recent investigations have revealed a prominent role for fast acting neurotransmitter pathways for temporally and spatially precise control of neural processing. Corticocortical and thalamocortical glutamatergic projections can rapidly and precisely control brain state by changing both the nature of ongoing activity and by controlling the gain and precision of neural responses.