Scientific Reports
February 16, 2021
Catherine Duclos, Danielle Nadin, Yacine Mahdid et al.
28 citations
Three-node network motifs—recurring patterns of connections—reorganize in the brain during anesthetic-induced unconsciousness and recovery. In nine healthy volunteers undergoing a 3-hour anesthesia protocol, electroencephalography (EEG) recordings in the alpha band (8–13 Hz) showed that two specific motifs (motifs 1 and 5) changed their topology significantly between responsive and unresponsive states. Motif 1 consisted of long-range chain-like connections, while motif 5 comprised short-range loop-like connections. The topological reorganization of motif 5 preceded the return of responsiveness, and motif 1 accompanied it, suggesting these motifs may help reveal neural correlates of consciousness.
Cell Reports
April 23, 2024
Adeeti Aggarwal, Jennifer Luo, Helen Chung et al.
17 citations
Traveling cortical waves in the 3-6 Hz range coordinate neuronal activity across visual and parietal cortex only in brain states where perception is possible. In awake mice, visual stimuli reset spontaneous waves, producing stimulus-evoked feedback waves that entrain neurons. Under anesthesia, visual stimuli fail to disrupt spontaneous waves. During ketamine-induced dissociation, spontaneous waves themselves traverse the cortex caudally and entrain neurons, mimicking the stimulus-evoked pattern seen in wakefulness. Thus, coordinated neuronal assemblies orchestrated by traveling waves emerge in states that allow perception, but only the awake state reliably links this coordination to external visual input.
Frontiers in Psychiatry
May 14, 2018
Ben J Palanca, Hannah R. Maybrier, Angela M. Mickle et al.
16 citations
Electroconvulsive therapy (ECT) deliberately induces generalized seizures to treat severe psychiatric illness, offering a chance to study how consciousness, cognition, and brain activity recover after seizures. Fifteen patients with treatment-resistant major depressive disorder will receive right unilateral ECT under etomidate anesthesia. They will then undergo three treatments in randomized order: etomidate plus ECT, ketamine plus ECT, and ketamine plus sham ECT, repeated for six total sessions. Cognitive tests assess sensorimotor speed, working memory, and executive function before and after each treatment. The study will measure time to return of responsiveness, cognitive recovery trajectories, postictal delirium, and EEG changes. It aims to develop biomarkers for tailoring cognitive and emotional recovery in ECT patients.
The Journal of neuroscience : the official journal of the Society for Neuroscience
May 14, 2025
Diego G Dávila, Andrew McKinstry-Wu, Max B Kelz et al.
5 citations
During wakefulness, people respond to external stimuli, while in dreams or drug-induced dissociated states, vivid internal experiences occur with reduced perception of the outside world. The brain's activity near a critical point between damped and exploding oscillations is linked to conscious experience, and this signature appears in both normal wakefulness and dissociative states but not in dreamless sleep or anesthesia. Using high-density EEG in human male volunteers given escalating ketamine doses, activity became progressively more stable, especially at higher frequencies, as dissociative symptoms increased. This stabilization correlated with reduced ability to perceive external stimuli, not with conscious experience itself. Combining statistical and dynamical measures of criticality may help distinguish wakefulness, dissociation, and unconsciousness.
Nature Communications
April 3, 2025
Joseph Cichon, Thomas Joseph, Xinguo Lu et al.
A single dose of inhaled nitrous oxide (N2O) rapidly and durably activates a specific population of neurons in the cingulate cortex of rodents exposed to chronic stress. This activation rescues a stress-induced hypoactivity state in layer V (L5) pyramidal neurons and is necessary for N2O's antidepressant-like effects. Although N2O is believed to work primarily by blocking NMDA receptors, L5 neurons still activate when NMDA receptor function is inhibited. Instead, N2O inhibits calcium-sensitive potassium (SK2) channels, driving L5 neuron activity and antidepressant-like effects. These findings identify a novel molecular and circuit mechanism for N2O's fast antidepressant action.
Joseph Cichon, Thomas Joseph, Xinguo Lu et al.
A single dose of inhaled nitrous oxide (N2O) rapidly activates layer V (L5) pyramidal neurons in the cingulate cortex of rodents exposed to chronic stress, rescuing a stress-associated hypoactivity state. This activation persists after exposure and is necessary for N2O's antidepressant-like effects. Although N2O is believed to act primarily through NMDA-receptor antagonism, L5 neurons activate even when NMDA-receptor function is blocked. Instead, N2O-induced inhibition of calcium-sensitive potassium (SK2) channels drives specific L5 activity and the ensuing antidepressant-like effects. These results indicate that N2O's fast antidepressant action relies on novel molecular actions in distinct cortical cell types.
Joseph Cichon, Thomas Joseph, Andrzej Z Wasilczuk et al.
A single dose of inhaled nitrous oxide (N2O) rapidly and specifically activates layer V (L5) pyramidal neurons in the prefrontal cortex of rodents exposed to chronic stress. This activation reverses a stress-linked hypoactivity state, persists after N2O exposure, and is necessary for the antidepressant effect. The activation occurs independently of NMDA-receptor function and synaptic activity, contrary to N2O's purported mechanism. Instead, N2O inhibits calcium-sensitive potassium (SK2) channels, driving both rapid and sustained L5 activity and antidepressant-like effects. The findings suggest a novel molecular target for fast-acting antidepressants.