Principal Components Analysis

Recurrent dynamics are thought to be central to computation in the cerebral cortex. Yet, how these dynamics differ across areas remains unknown. Here, we used two-photon microscopy to image Ca2+ activity from hundreds of neurons and while delivering brief, focal excitatory input with near-cellular- resolution optogenetics. Specifically, we compared how the primary visual (V1) and the secondary motor (M2) cortices distinctly sustain this input while mice ran spontaneously. Single-neuron responses to focal stimulation were much more prevalent in M2 than V1. Moreover, evoked network-level dynamic

Social interactions in primates are possible through the ability to extract relevant information from voices, for example their identity. The anterior Temporal Voice Area (aTVA) is a region in the anterior temporal lobe of humans, macaques and marmosets specialized in the processing of voices, but the exact voice information represented by individual neurons in the aTVA remains obscure.Here we asked how aTVA neurons encode voice identity information, separating different identities and grouping together calls from a same identity. We implanted two rhesus macaques with high-density multi-electr

The collective spiking activity of hippocampal principal cells supports information processing and integration for memory-guided behaviour. This population spiking is temporally structured and reflect behavioural states. That is, hippocampal principal cell spiking is sparsely paced by theta oscillations during active exploration but tightly synchronised by sharp-wave/ripples (SWRs) during sleep/rest. Notably, previous studies have related SWRs to a current sink in the stratum radiatum, reporting CA3 inputs that serve memory consolidation. Here, we explore whether individual SWRs deviate from t

…methods – standard techniques, like principal components analysis,

Sensory representations are typically thought as neuronal activity patterns that encode physical attributes of the outside world. However, increasing evidence is showing that as animals learned the association between a sensory stimulus and its behavioral relevance, stimulus representation in sensory cortical areas can change. In this seminar I will present recent experiments from our lab showing that the activity in the olfactory piriform cortex (PC) of mice encodes not only odor information, but also non-olfactory variables associated with the behavioral task. By developing an associative ol

Many networks in the brain are sparsely connected, and the brain eliminates synapses during development and learning. How could the brain decide which synapses to prune? In a recurrent network, determining the importance of a synapse between two neurons is a difficult computational problem, depending on the role that both neurons play and on all possible pathways of information flow between them. Noise is ubiquitous in neural systems, and often considered an irritant to be overcome. In the first part of this talk, I will suggest that noise could play a functional role in synaptic pruning, allo