Neuron
May 15, 2024
Johan F Storm, P Christiaan Klink, Jaan Aru et al.
108 citations
Consciousness may be explained by multiple, partly compatible theories rather than a single winner. A group of scientists representing different theories argue that various accounts often address different aspects or mechanistic levels of conscious experience, so they do not necessarily contradict each other. Instead, several theories may converge on fundamental neuronal mechanisms and be complementary, allowing multiple perspectives to simultaneously advance understanding. The authors advocate for unifying, integration-oriented approaches that combine valuable elements from diverse theories, an approach that has so far been largely neglected.
Neuroscience of consciousness
January 1, 2024
André Sevenius Nilsen, Alessandro Arena, Johan F Storm
10 citations
In rats under propofol, sevoflurane, and ketamine anesthesia, the perturbational complexity index (PCI) and two spontaneous EEG measures—Lempel-Ziv complexity (LZ) and geometric integrated information (ΦG)—best distinguished awake from anesthetized states for propofol and sevoflurane. However, PCI was anti-correlated with spontaneous measures of integrated information, which increased during propofol and sevoflurane anesthesia, contrary to expectations. The divergence suggests anesthesia disrupts global cortico-cortical information transfer, while spontaneous activity suggests the opposite, possibly due to suppressed encoding specificity or driving subcortical projections. Perturbation-based and spontaneous measures may be complementary for studying altered consciousness.
PloS one
January 1, 2024
Nicholas Hagger-Vaughan, Daniel Kolnier, Johan F Storm
2 citations
A newly described type of depolarising plateau potential (PP) in layer 2/3 pyramidal cells of rat prefrontal cortex slices generates sustained spiking that outlasts the triggering stimulus. Unlike previously known plateau potentials that rely on the apical dendrite, these PPs persist even when the apical dendrite is severed, and are sustained by calcium application only to the soma and basal dendrites. They depend on metabotropic cholinergic or glutamatergic modulation and on TRPC4 and TRPC5 cation channels, requiring external calcium and internal calcium stores but not voltage-gated calcium channels. These PPs may underlie sustained activity important for working memory, access consciousness, and executive functions.
PloS one
January 1, 2025
Anne S Fleiner, Daniel Kolnier, Nicholas Hagger-Vaughan et al.
1 citation
Propofol and ketamine, two common general anesthetics, affect consciousness differently—propofol produces a deeply unconscious state with few dreams, while ketamine often leads to vivid dreaming. In rat brain slices of the medial prefrontal cortex, an area linked to conscious access and working memory, researchers added muscarine to mimic an aroused state and recorded electrical activity in layer 2/3 pyramidal cells. Muscarine triggered long-lasting depolarizing plateau potentials and spiking. Pre-incubation with a low dose of propofol reduced these plateau potentials and significantly reduced spiking, whereas a low dose of ketamine appeared to enhance them, though not significantly. A high dose of ketamine suppressed both. The contrasting effects on plateau potentials may relate to the different clinical experiences of dreaming under these drugs.