McGill University — QLS-CAMBAM Seminar Series

The brain adjusts its internal activity to direct visual and auditory attention and regulate responses to external stimuli. Appropriate endogenous activity may support normal cognition and behaviour, while its modulation can also produce dysfunction. Beginning with mathematical models of general anaesthesia, this talk examines how changes in noisy endogenous activity can fragment functional brain organization and account for loss of consciousness. Anaesthesia experiments in ferrets support the theoretical result. Further experimental examples are discussed to show how underlying internal noise may help explain observed transitions between brain states.

Why do dorsal raphe serotonin neurons respond to reward, surprise, salience and uncertainty in ways that resist a single explanation? This talk proposes that serotonin activity encodes prospective value: a prediction of cumulative future reward. The model is motivated by the unusually strong and persistent spike-frequency adaptation of these neurons, which may support efficient and accurate predictions. It reproduces important qualitative features of serotonergic responses that earlier models miss and predicts measured in vivo firing rates more accurately than competing accounts. By treating previously separate responses as manifestations of one prospective value code, the work connects serotonin physiology to its computational roles in learning and behaviour.

Reproducible research can turn scientific observations into reliable, reusable knowledge. This talk presents ReproNim and related community infrastructure for sharing data and computational workflows. It examines versioned, re-executable analysis at scale using OpenNeuro, together with harmonization and querying across dozens of research sites. ReproLakes and ReproPonds combine public and private metadata stores with FAIR and reproducible practices to improve discovery and reuse. The discussion addresses both technical obstacles and research-culture challenges, offering practical approaches for making shared scientific resources more useful and accelerating cumulative discovery.

How do humans stabilize an inverted pendulum, and why does a balanced pole eventually fall? Drawing on 25 years of fingertip pole-balancing research, this talk examines neural correction delays: longer poles move more slowly relative to the nervous system’s response time. Delay-differential models can stabilize the upright position, yet skilled people still experience falls. The proposed explanation is microchaos arising from interactions among delay, sensory dead zones and frequency-dependent force encoding. A region of transient falling solutions lies next to stable microchaotic dynamics. Such microchaos is absent in virtual frontal-plane balancing tasks, while models of standing postural sway lack the corresponding transient regime. The comparison suggests that human falls, unlike pole falls, are more plausibly associated with medical events or slips and trips.