eNeuro
March 1, 2016
Victoria Phoumthipphavong, Florent Barthas, Samantha Hassett et al.
142 citations
A single low dose of ketamine, an NMDA receptor antagonist, produces fast-acting antidepressant effects. In mice, a single injection of ketamine increased dendritic spine density in the medial frontal cortex for up to two weeks compared to saline-injected controls. This prolonged increase was driven by a higher rate of new spine formation, not by changes in spine elimination. Some new spines persisted, indicating functional synapses. In a few cases, distal apical tuft branches retracted the day after ketamine administration. These findings suggest that ketamine causes immediate removal of some dendritic inputs and gradual addition of others, consistent with a rebalancing of synaptic inputs onto frontal cortical neurons.
eNeuro
August 1, 2024
Sana Khan, Yixiang Huang, Derin Timuçin et al.
23 citations
Volatile anesthetics like isoflurane may cause unconsciousness by binding to microtubules (MTs) inside neurons and dampening their quantum optical effects. In male rats injected with the MT-stabilizing drug epothilone B (epoB), loss of righting reflex under 4% isoflurane took an average of 69 seconds longer than in rats given a placebo. The difference was statistically significant with a large effect size (Cohen's d = 1.9) and could not be explained by tolerance from repeated anesthetic exposure. This supports the idea that consciousness arises from quantum physical states in neural microtubules, as proposed in the orchestrated objective reduction (Orch OR) theory.
eNeuro
October 1, 2025
Tanner L. Anderson, Artin Asadipooya, Pavel I. Ortinski
3 citations
Psychedelic drugs like DOI can reverse the direction of synaptic plasticity in the claustrum, a brain region rich in serotonin 2 receptors and heavily connected to the anterior cingulate cortex. In male rats, pairing presynaptic stimuli with postsynaptic action potentials in claustrum neurons projecting to the ACC caused DOI to flip the plasticity from long-term depression to long-term potentiation, an effect specific to locally activated synapses. DOI also altered several action potential dynamics in these neurons. The findings support the idea that psychedelics induce rapid and lasting neuroplasticity and that claustrocortical circuits are especially sensitive to these drugs, offering a potential mechanism for their therapeutic effects.
eNeuro
March 1, 2025
Sarah D Jennings, Devin P Hagarty, Jordan Logue et al.
1 citation
Repeated ketamine infusions for depression may be riskier in people with a history of alcohol use, and effects differ by sex. In rats, females self-administered more ketamine than males. A history of alcohol increased ketamine intake in females, while a history of either isolation or alcohol independently increased ketamine intake in males. All groups showed similar extinction and cue-induced reinstatement. In the nucleus accumbens, isolation increased immature dendritic spines in males, an effect reduced by alcohol; alcohol increased immature spines in females. The findings suggest that prior social isolation and alcohol exposure alter ketamine's reinforcing properties in a sex-dependent manner, highlighting the need to consider sex and alcohol history when using ketamine to treat depression.
eNeuro
July 7, 2025
Andy Jeesu Kim, Keran Chen, Ying Tian et al.
Thirty days of guided mindfulness meditation using a mobile app improved the speed of saccadic eye movements (overt orienting of attention) in adults, but did not reduce distractibility or enhance goal-directed attentional control beyond repeated task practice. The benefits were similar across young, middle-aged, and older adults, and no changes appeared in self-report mindfulness questionnaires. The findings suggest that short-term mindfulness practice can modulate cognition in ways detectable by eye tracking but not by self-report, and that age does not moderate these effects.
eNeuro
October 1, 2024
Michael S A Graziano
Illusionism offers a philosophical framework for theories of consciousness that avoids invoking a magical mind essence. The brain's internal models are never fully accurate, so some element of illusionism is necessary for any working theory of consciousness accessed through introspection. The article describes the illusionist framework and proposes six specific theories, demonstrating the range of possibilities in an underexplored domain. It argues that existing theories like integrated information theory or global workspace theory can be strengthened by adding an illusionist layer, and that illusionist logic allows disparate theories to converge onto a deeper, unified understanding.
eNeuro
September 1, 2024
Simone Ciceri, Matthijs N Oude Lohuis, Vivi Rottschäfer et al.
Conscious report of visual input correlates with two distinct neural responses in the primary visual cortex (V1): an early response tied to stimulus features and a late response linked to report or detection. This late wave, central to theories of consciousness, was thought to be driven by the prefrontal cortex (PFC). Analyzing two electrophysiological studies in mice performing detection tasks, researchers characterized activity in V1, posterior parietal cortex (PPC), and PFC. A minimal network model constrained by known connectivity showed that while PFC is necessary to generate report-related activity in V1, it only does so through PPC mediation. PPC, not PFC, ultimately enables the late wave of V1 activity.
eNeuro
January 1, 2021
Matthew S Willsey, Chrono S Nu, Samuel R Nason et al.
Inhaling 70% nitrous oxide (N2O) increases spiking rates and beta- and gamma-band power in the primary motor cortex of macaques while degrading the representation of somatosensory information. The proportion of correctly classified finger touches dropped from 0.50 to 0.34 during N2O inhalation, indicating impaired information transfer. The increased firing rate was not correlated with changes in neuronal tuning, suggesting a dissociation between overall activity and sensory processing.
eNeuro
January 1, 2021
Ana Y Martínez, Athena Demertzi, Clemens C C Bauer et al.
Focused attention on spontaneous body sensations requires interoceptive abilities and is impaired in disorders like illness-anxiety disorder. Fifteen experienced meditators performed a 20-minute attentional task to spontaneous sensations during fMRI scanning, with resting-state scans before and after the task. Dynamic functional connectivity and k-means clustering identified five recurring connectivity patterns across the dorsal attention, default mode, and frontoparietal networks. Subjects spent more time in a low-connectivity pattern during rest and more time in complex patterns during the task. A carry-over effect in connectivity after the task suggests an active role in learning from cognitive training. Focused attention to interoception involves a distinct dynamic brain organization compared to rest.
eNeuro
November 1, 2019
Repeated meditation practice can reconfigure brain networks, shifting transient meditative states into lasting trait changes. The study examines how central executive and default mode networks reorganize with meditation, suggesting that regular practice strengthens cognitive control and reduces self-referential thought. This neural reconfiguration may underlie the long-term benefits of meditation on attention and emotional regulation.
eNeuro
January 1, 2017
Andrew M. Haun, Masafumi Oizumi, Christopher K Kovach et al.
A pattern of integrated information—a measure inspired by integrated information theory—corresponds to what a person consciously sees, whereas broader information measures such as mutual information and entropy do not. Intracranial recordings from six neurosurgical patients showed that, in object-sensitive brain areas, the hierarchical causal structure of neural interactions matched the subjects' conscious percepts when they viewed faces or objects under conditions that dissociate perception from the physical stimulus (continuous flash suppression and backward masking). Unsupervised classification confirmed that integrated information patterns, but not other information measures, clustered according to the subjects' visual experiences. The findings suggest that locally integrated information plays a key role in the neural basis of conscious object perception.