Biology subjects

De Filippo, R.

Publications and source records attributed to De Filippo, R..

4 recordsLinked to original sources

bioRxiv2026

Psilocybin collapses visual change detection and drives cortical dynamics toward a state of surprise

Psilocybin profoundly alters visual perception, yet the neuronal mechanisms underlying these effects remain unclear. Here we combined large-scale Neuropixels recordings with cell-type specific optogenetics in head-fixed mice performing a visual change-detection task. Psilocybin severely impaired task performance without overt motor deficits. In cortex, the drug modestly suppressed activity of layer 5 neurons while preserving representations of image identity. By contrast, psilocybin imposed a 4-Hz oscillation on visually evoked activity that preferentially affected neurons encoding image change rather than image identity. Under psilocybin, expected image repetitions aberrantly recruited change-encoding ensembles and shifted cortical population dynamics towards trajectories normally evoked by genuine stimulus changes. These effects were strongest in somatostatin-expressing (SST) interneurons in visual cortex. The strength of this modulation depended on image structure and was greatest for images with clear, continuous contours, which preferentially recruited change-encoding ensembles. These findings demonstrate that psilocybin drives internally generated cortical surprise signals, providing a circuit mechanism for altered perception in the acute psychedelic state.

neuroscience↗

bioRxiv2026

Brain-wide reconfiguration of burst firing by psilocybin reveals 5-HT2A-dependent circuit dynamics

Psilocybin produces rapid and lasting therapeutic effects, yet how 5-HT2A receptor activation reshapes brain-wide circuit dynamics during acute drug administration remains poorly understood. Using simultaneous multi-region Neuropixels recordings of 46,360 single units from 35 mice, together with scalp electroencephalography (EEG), pupillometry, and locomotion monitoring, we provide a brain-wide, single-unit and field-potential characterization of psilocybin's acute effects, with pharmacological dissection using the 5-HT2A antagonist ketanserin. Psilocybin selectively reconfigured burst coding, rather than mean firing rate, across cortical, thalamic, and hippocampal circuits: burst firing decreased in hippocampal CA1-CA3 and was bidirectionally modulated in the thalamus, with the reticular nucleus bursting more and first-order geniculate nuclei bursting less. Critically, most of these burst effects were abolished by ketanserin, consistent with at least partial 5-HT2A receptor dependence. These data suggest that the psychedelic state is not simply a matter of how much neurons fire, but of how they fire, pointing to a region-specific, 5-HT2A-associated reconfiguration of burst coding that may underlie the acute phenomenology of the psilocybin experience.

neuroscience↗

bioRxiv2026

Local inhibitory topology dictates the spatial compartmentalization of hippocampal sharp-wave ripples

Hippocampal sharp-wave ripples (SWRs) are essential for memory consolidation and represent among the most synchronous oscillatory events in the brain. Yet, despite their capacity for widespread synchronization, SWRs frequently remain confined to discrete hippocampal domains, revealing a paradox between global coordination and local autonomy. Here, by analysing existing in vivo recordings with an experimentally constrained three-dimensional biophysical model, we show that inhibitory activity and inhibitory topology serve fundamentally distinct functions. Whereas perisomatic inhibition gates SWR generation and dendritic inhibition regulates the strength and spectral properties of ripple oscillations, the spatial organization of inhibitory connectivity establishes local computational domains that enable autonomous ripple generators to coexist. Together, our findings identify a spatial dimension of inhibition, in which inhibitory activity governs the emergence and dynamics of SWRs, while inhibitory topology determines their spatial organization and autonomy.

neuroscience↗

bioRxiv2022

Differential ripple propagation along the hippocampal longitudinal axis

Hippocampal ripples are highly synchronous neural events critical for memory consolidation and retrieval. A minority of strong ripples has been shown to be of particular importance in situations of increased memory demands. The propagation dynamics of strong ripples inside the hippocampal formation are, however, still opaque. We analyzed ripple propagation within the hippocampal formation in a large open access dataset comprising 267 Neuropixel recordings in 49 awake, head-fixed mice. Surprisingly, strong ripples (top 10% in ripple strength) propagate differentially depending on their generation point along the hippocampal longitudinal axis. The septal hippocampal pole is able to generate longer ripples that engage more neurons and elicit spiking activity for an extended time even at considerable distances. Accordingly, a substantial portion of the variance in strong ripple duration (R{superscript 2} = 0.463) is explained by the ripple generation location on the longitudinal axis. Our results are consistent with a possible distinctive role of the hippocampal septal pole in conditions of high memory demand.

neuroscience↗