Biology subjects

Nicholas, C. R.

Publications and source records attributed to Nicholas, C. R..

3 recordsLinked to original sources

bioRxiv2025

Electrophysiological effects of psilocybin co-administered with midazolam

The serotonergic psychedelic psilocybin induces neural plasticity and profoundly alters consciousness. The benzodiazepine midazolam blunts neural plasticity and induces conscious sedation and amnesia at low doses. In our recent open label pilot study, we administered oral psilocybin (25 mg) along with intravenous midazolam at doses allowing a full psychedelic experience while blunting memory for the experience. We previously reported preliminary results from high density scalp electroencephalography (EEG) recorded during the dosing session. Here, we examined changes in EEG band power, normalized Lempel Ziv complexity (LZCn), and spectral exponent. We used linear mixed effects models that incorporated time and the subjective effects of midazolam and psilocybin, measured with the Observers Assessment of Arousal and Sedation (OAA/S) and selected items from the Altered States of Consciousness (ASC) questionnaire, respectively. At 15-30 mins, when midazolam (but likely not psilocybin) was at its targeted effect site concentration, we observed increased beta power and decreased spectral exponent. As the subjective effects of psilocybin commenced and over the next six hours, we observed increased LZCn and spectral exponent and decreased broadband power. OAA/S improved model fits for alpha power while ASC improved model fits for LZCn and spectral exponent. These data are further evidence that the effects of psilocybin are maintained in the presence of midazolam, supporting its utility in mechanistic studies of psilocybins therapeutic activity.

neuroscience↗

bioRxiv2024

Human stem cell-derived GABAergic interneuron development reveals early emergence of subtype diversity followed by gradual electrochemical maturation

Medial ganglionic eminence-derived inhibitory GABAergic pallial interneurons (MGE-pINs) are essential regulators of cortical circuits; their dysfunction is associated with numerous neurological disorders. We developed human (h) MGE-pINs from pluripotent stem cells for the treatment of drug-resistant epilepsy. Here, we analyzed xenografted hMGE-pINs over the lifespan of host mice using single nuclei RNA sequencing. Comparative transcriptomics against endogenous human brain datasets revealed that 97% of grafted cells developed into somatostatin (SST) and parvalbumin (PVALB) subtypes, including populations that exhibit selective vulnerability in Alzheimers disease. Transplanted hMGE-pINs demonstrated rapid emergence of subclass features, progressing through distinct transcriptional states sequentially involving neuronal migration, synapse organization, and membrane maturation. We present molecular, electrophysiological, and morphological data that collectively confirm the derivation of diverse bona-fide human SST and PVALB subtypes, providing a high-fidelity model to study human MGE-pIN development and functional maturation as well as a compositional atlas for regenerative cell therapy applications.

neuroscience↗

bioRxiv2024

Co-administration of midazolam and psilocybin: Differential effects on subjective quality versus memory of the psychedelic experience

Aspects of the acute experience induced by the serotonergic psychedelic psilocybin predict symptomatic relief in multiple psychiatric disorders and improved well-being in healthy participants, but whether these therapeutic effects are immediate or are based on memories of the experience is unclear. To examine this, we co-administered psilocybin (25 mg) with the amnestic benzodiazepine midazolam in 8 healthy participants and assayed the subjective quality of, and memory for, the dosing-day experience. We identified a midazolam dose that allowed a conscious psychedelic experience to occur while partially impairing memory for the experience. Furthermore, midazolam dose and memory impairment tended to associate inversely with salience, insight, and well-being induced by psilocybin. These data suggest a role for memory in therapeutically relevant behavioral effects occasioned by psilocybin. Because midazolam blocks memory by blocking cortical neural plasticity, it may also be useful for evaluating the contribution of the pro-neuroplastic properties of psychedelics to their therapeutic activity.

neuroscience↗