NEXT: January 19th, 2021, 1:30PM – virtual meeting
Speaker: Michele Nardin (IST AUSTRIA- Csicsvari Group)
Title: Coupling structure of prefrontal-hippocampal cell pairs underlying spatial abstraction
Hippocampal activity is strongly modulated by the position of the individual in space. The prefrontal cortex also holds spatial information, and is physically and functionally connected to the hippocampus; nonetheless, the nature of the information exchanged between the two areas is unclear. Here, with simultaneous recordings from the two areas of rats running on a plus maze, we show that there is a directional flow of spatial information from the hippocampus to the prefrontal cortex. We prove that cell pairs across areas are coupled, creating patterns that explain the symmetric firing fields of prefrontal cells. These results match the expectations of a simple normative model of spatial information transfer and generalization. Our observations offer a possible mechanism of spatial abstraction from hippocampus to prefrontal cortex
Speaker: Lisa Knaus (IST AUSTRIA- Novarino Group)
Title: Studying the amino acid transporter Slc7a5 and its role in modulating activity and survival of newborn neurons
The solute carrier transporter 7a5 (SLC7A5), a large neutral amino acid transporter, has a crucial role in maintaining branched chain amino acid (BCAA) levels in the brain. In patients, a loss of SLC7A5 is a rare cause of autism, motor defects and severe microcephaly. By employing a set of conditional and mosaic mouse models targeting radial glia progenitor cells, we aim to dissect the molecular mechanisms underlying the microcephalic phenotype of the patients.
Adult Slc7a5 cKO mice present with a severe reduction in cortical thickness, caused by increased apoptotic activity in the postnatal cortex. Interestingly, these elevated rates of cell death co-occur with an endogenous wave of neuronal apoptosis. This timely coordinated apoptotic program has been shown to be regulated by the activity levels of cortical pyramidal neurons and is crucial for the process of network refinement. To probe a potential link between the loss of Slc7a5 and decreased neuronal activity levels during this aforementioned time window, we performed current clamp recordings in Slc7a5 cKO and mosaic animals. We found that mutant pyramidal neurons indeed transiently reduce their firing rate in a cell-autonomous manner. These findings point towards a novel cell-type specific mechanism, whereby the expression of an amino-acid-transporter is temporally coordinated with neuronal activity to ensure survival of newborn neurons.