Biology subjects

Sauer, J.-F.

Publications and source records attributed to Sauer, J.-F..

3 recordsLinked to original sources

bioRxiv2021

Disrupted-in-Schizophrenia-1 is required for proper pyramidal cell-interneuron communication and network dynamics in the prefrontal cortex.

We interrogated prefrontal circuit function in mice lacking Disrupted-in-schizophrenia-1 (Disc1-mutant mice), a risk factor for psychiatric disorders. Single-unit recordings in awake mice revealed reduced average firing rates of fast-spiking interneurons (INTs), including optogenetically identified parvalbumin-positive cells, and a lower proportion of INTs phase-coupled to ongoing gamma oscillations. Moreover, we observed decreased spike transmission efficacy at local pyramidal cell (PYR)-INT connections in vivo, suggesting a reduced excitatory effect of local glutamatergic inputs as a potential mechanism of lower INT rates. On the network level, impaired INT function resulted in altered activation of PYR assemblies: While assembly activations were observed equally often, the expression strength of individual assembly patterns was significantly higher in Disc1-mutant mice. Our data thus reveal a role of Disc1 in shaping the properties of prefrontal assembly patterns by setting prefrontal INT responsiveness to glutamatergic drive.

neuroscience↗

bioRxiv2021

Phase-specific pooling of sparse assembly activity by respiration-related brain oscillations

Nasal breathing affects cognitive functions, but it has remained largely unclear how respiration-driven inputs shape information processing in neuronal circuits. Current theories emphasize the role of neuronal assemblies, coalitions of transiently active pyramidal cells, as the core unit of cortical network computations. Here, we show that respiration-related oscillations (RROs) directly pace the activation of neuronal assemblies in the medial prefrontal cortex (mPFC) of mice. Neuronal assemblies are more efficiently entrained than single neurons and activate preferentially during the descending phase of RROs. At the same time, overlap between individual assemblies is minimized during descending RRO due to the efficient recruitment of GABAergic neurons by assemblies. Our results thus suggest the RROs support cortical operations by defining time windows of enhanced yet segregated assembly activity.

neuroscience↗

bioRxiv2021

Topographically organized representation of space and context in the medial prefrontal cortex

Spatial tuning of neocortical pyramidal cells has been observed in diverse cortical regions and is thought to rely primarily on input from the hippocampal formation. Despite the well-studied hippocampal place code, many properties of the neocortical spatial tuning system are still insufficiently understood. In particular, it has remained unclear how the topography of direct anatomical connections from hippocampus to neocortex affects spatial tuning depth, and whether the dynamics of spatial coding in the hippocampal output region CA1 such as remapping in novel environments is transmitted to the neocortex. Using mice navigating through virtual environments we addressed these questions in the mouse medial prefrontal cortex, which receives direct input from the hippocampus. We find a rapidly emerging prefrontal representation of space in the absence of task rules, which discriminates familiar from novel environments and is reinstated upon re-exposure to the same familiar environment. Topographical analysis revealed a dorso-ventral gradient in the representation of the own position, which runs opposite to the innervation density of hippocampal inputs. Jointly, these results reveal a dynamically emerging and topographically organized prefrontal place code during spontaneous locomotion. Significance StatementThe neocortex is composed of areas with specialized function (e.g. sensory vs. associational). Despite this functional diversity, emerging evidences suggest that the encoding of space might be a universal feature of cortical circuits. Here, we identified a gradient of spatial tuning depth along the dorso-ventral axis. A complex topography of spatial tuning properties might support a division of labor among medial prefrontal cortical subnetworks to support local circuit computation relevant for the execution of context-dependent behavioral outcomes.

neuroscience↗