Neural control of brain state

Abstract

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.

Reconstruction and Simulation of Neocortical Microcircuitry

“…While it is well known from previous theoretical findings that changing E-I balance changes the state of the network (Brunel, 2000;van Vreeswijk and Sompolinsky, 1996), the simulations further suggest that any mechanism that differentially changes the synaptic dynamics of different types of synapses (e.g., through neuromodulation; for reviews, see Lee and Dan, 2012;Zagha and McCormick, 2014) could alter the boundaries between activity regimes in complex ways. We speculate that other emergent properties, such as UP and DOWN states with two meta-stable fixed points, as observed in vivo (Steriade et al, 1993), which are not reproduced by the digital reconstruction, may require thalamocortical interactions (Hughes et al, 2002), cortico-cortical interactions (Timofeev et al, 2000), intrinsic oscillators (L} orincz et al, 2015;Sanchez-Vives and McCormick, 2000), or neuromodulation (Constantinople and Bruno, 2011;L} orincz et al, 2015;Sigalas et al, 2015).…”

Pupil fluctuations track rapid changes in adrenergic and cholinergic activity in cortex

“…Two of these are the LC, which provides the source of noradrenergic innervation, and the basal forebrain, which is the source of cholinergic innervation to the cortex49. These neurotransmitters can modulate the state of cortical activity through cell type-specific and subcellular mechanisms565051. Both cholinergic and noradrenergic neurons show graded and transient increases in firing in relation to increased attention to external stimuli, arousal and locomotion13485253.…”

Rapid Sensory Adaptation Redux: A Circuit Perspective

“…Brain state plays an important role in shaping spontaneous neural activity as well as sensory evoked responses (Anderson et al, 2000; Buonomano and Maass, 2009; McCormick et al, 2015; Petersen et al, 2003; Poulet and Petersen, 2008; Zagha and McCormick, 2014) and therefore will impact encoding properties in the sensory pathways. Given that the state of the synapse is a function of activity levels, it follows that reduced synaptic efficacy will be present in thalamocortical neurons during states of arousal or with ongoing neural activity (Boudreau and Ferster, 2005; Castro-Alamancos and Oldford, 2002).…”