BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Memento EPFL// BEGIN:VEVENT SUMMARY:From systematic interneuron perturbations to connectome-constraine d dynamics DTSTART:20260609T113000 DTEND:20260609T123000 DTSTAMP:20260603T050527Z UID:566323f0cda2f32f662887fc917028414866e3631e01cfddc08c1905 CATEGORIES:Conferences - Seminars DESCRIPTION:Alisa Gross \nQuantitative understanding of neural control over behavior requires characterizing computations perfo rmed along information-processing pathways. In principle\, Caenorhabditis elegans is ideally suited for this goal since it generates non-trivial\, c ontext-dependent behavior with a relatively small nervous system. Existing anatomical and functional connectomes represent major advances but also m iss important synaptic details and critical connectivities\, respectively. Whole-brain functional imaging\, another important approach\, by itself o nly reveals correlations. A perturbation-based\, causal atlas is needed to pin down neuronal computations in the context of behavior\, including red undancies\, synergies\, and time constants. We sought to satisfy this need through systematic chemogenetic perturbation\, combined with connectome-c onstrained generative modeling. Using reversible chemogenetic silencing co mbined with whole-brain calcium imaging\, we silenced seven head interneur ons individually and in pairs: two act as opposing controllers of forward- reverse states\, interneuron activity predicts behavior at lags of 15-25 s econds\, and pairwise silencing reveals structured non-additivity. In para llel\, we developed a connectome-constrained recurrent dynamical system tr ained on freely-behaving whole-brain recordings\, with three current layer s (gap-junction\, fast-synaptic\, extrasynaptic) and multi-timescale kinet ics. On a 40-animal cohort\, our architecture beats unconstrained baseline s\, ties anatomy-masked models on neural prediction\, and transfers across animals by relabeling parameters alone\, while anatomy-masked baselines c ollapse to negative R^2. Three independent analyses recover the canonical locomotor circuit without being built in. The two approaches converge on t he same interneuron\, identified by silencing as a key modulator of revers al behavior. Our work demonstrates advantages of integrating cell-specific perturbation with connectome-constrained modeling\, and motivates extendi ng this approach to larger nervous systems. LOCATION:GA 3 21 https://plan.epfl.ch/?room==GA%203%2021 STATUS:CONFIRMED END:VEVENT END:VCALENDAR