Neural assemblies coordinated by cortical waves are associated with waking and hallucinatory brain states.
Cell reports – April 23, 2024
Source: PubMed
Summary
Brain waves that sweep across the cortex like waves on a beach play a crucial role in how we perceive reality. During wakefulness, visual stimuli trigger organized waves that coordinate neural activity across brain regions. Under anesthesia with isoflurane, these waves stop responding to visual input. Intriguingly, ketamine creates a unique state where similar wave patterns occur spontaneously, possibly explaining its hallucinatory effects.
Abstract
The relationship between sensory stimuli and perceptions is brain-state dependent: in wakefulness, suprathreshold stimuli evoke perceptions; under anesthesia, perceptions are abolished; and during dreaming and in dissociated states, percepts are internally generated. Here, we exploit this state dependence to identify brain activity associated with internally generated or stimulus-evoked perceptions. In awake mice, visual stimuli phase reset spontaneous cortical waves to elicit 3-6 Hz feedback traveling waves. These stimulus-evoked waves traverse the cortex and entrain visual and parietal neurons. Under anesthesia as well as during ketamine-induced dissociation, visual stimuli do not disrupt spontaneous waves. Uniquely, in the dissociated state, spontaneous waves traverse the cortex caudally and entrain visual and parietal neurons, akin to stimulus-evoked waves in wakefulness. Thus, coordinated neuronal assemblies orchestrated by traveling cortical waves emerge in states in which perception can manifest. The awake state is privileged in that this coordination is reliably elicited by external visual stimuli.