Awake Dynamics of Thalamocortical Processing

Hosted by Jérémie and Greg

External speaker

Quentin Perrenoud, Ph.D.

Position: Postdoc, Cardin Lab, Yale University School of Medicine

Title: Flexible perceptual encoding by discrete gamma events in mouse V1

Cognitive processes underlying behavior are linked to specific spatiotemporal patterns of neural activity in the neocortex. These patterns arise from synchronous synaptic activity and are generally analyzed as local oscillations. However, they also display aperiodic dynamics which this approach may not capture. Here, we develop a method decomposing patterned activity into discrete network events which we apply to track γ activity (30-80Hz) in mouse visual cortex (V1). We find that γ events often cluster in oscillatory bouts but also occur in isolation and that their rate is correlated with arousal and locomotion. Individual events synchronize neural firing across layers and promote visual encoding. V1 γ events are suppressed by optogenetic modulation of the dorsal lateral geniculate nucleus (dLGN) and evoked by patterned activation of dLGN terminals suggesting that they are linked to thalamocortical integration of visual information. In behaving mice, γ event rate increases prior to visually cued behavioral responses predicting trial-by-trial performance and, suppressing γ events impairs visual detection while evoking them elicits response. This relationship is sensory modality-specific and rapidly modulated by changes in task objectives. γ events thus support a selective and flexible encoding of visual information according to behavioral context.

Local Berlin speaker

Jérémie Sibille, Ph.D.

Position: Postdoc, Schmitzlab, Charité-Universitätsmedizin Berlin

Title: Awake dynamics of thalamocortical processing

Behavioral modulation of cortical activity is believed to support different types of cognitive computation, yet its origins remain poorly understood. In particular, it is unclear whether elevated cortical firing during behavior arises from enhanced thalamic inputs or from other cortical inputs. Here, we used tangential insertions of high-density electrodes to capture thalamocortical and intracortical connectivity across distinct behavioral states, including running and whisking bouts. Our results show that thalamic inputs increase in parallel with cortical activity across all behavioral conditions, indicating a tight synchronization between interconnected thalamic and cortical visual areas. Strikingly, generalized linear models revealed that behavioral context strongly predicted neuronal firing in both thalamic and cortical populations within primary visual areas, content which is preferentially transmitted within excitatory synapses. Despite robust firing changes in both pathways, synaptic transmission from thalamic inputs exhibited greater stability across behavioral states compared to intracortical inputs. These findings suggest that while thalamic connections reliably convey information, intracortical synapses may support more dynamic and behaviorally flexible computations within cortical circuits.

 

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This event is part of the PostDoc Network Speaker Series.

Guests are welcome!