Biology subjects

Damo Kamda, J. L.

Publications and source records attributed to Damo Kamda, J. L..

3 recordsLinked to original sources

bioRxiv2026

Sensory experience and mTORC1 interplay orchestrates the maturation of cortical interneuron connectivity and tactile sensitivity

Sensory abnormalities are core features of neurodevelopmental disorders, including autism. Although interneuron dysfunction is hypothesized to contribute to these deficits, the underlying mechanisms remain unclear. Here, we demonstrate that mTORC1 dysregulation in parvalbumin-expressing (PV) interneurons drives heightened tactile exploration and defensiveness. These behavioral changes coincide with whisker-evoked cortical responses characterized by increased power but degraded temporal precision. Excitatory inputs to PV cells, their intrinsic excitability and in vivo firing rate during tactile exploration are reduced, suggesting that mutant PV cells are hypoactive. Whisker trimming restricted to the third postnatal week prevented mTORC1 hyperactivation, PV cell input and output connectivity deficits as well as abnormal tactile cortical responses and behavior in adult mutant mice. Further, this manipulation rescued sociability deficits. Altogether, these data suggest that the interplay between mTORC1 signaling and sensory experience in PV cells regulates their connectivity, and contributes to the proper development of tactile and social behavior.

neuroscience↗

bioRxiv2026

The Appetite for Freediving differs between Sprague-Dawley and Long Evans Rats.

Freediving in rats has emerged as a relevant model to study physiology and neural adaptation underlying submersion mechanisms. However, despite well-established strain-dependent differences in behaviour and physiological responses, most studies about freediving rely on Sprague Dawley rats. As the choice of strain could significantly shape experimental results depending on the field of research, we conducted a behavioural comparative study between Long Evans (LE) rats, genetically closer to the wild Norway rat, with the commonly used Sprague Dawley (SD) strain. We developed an 11-week progressive voluntary freediving protocol involving four distances (from 5 to 11 meters), and assessed the rats' natural willingness to dive and swim, and identified several parameters for evaluation of their confidence (waiting time before diving, speed), performance capacity (freediving time) and population variability. We found that Long Evans rats were naturally more willing to dive and more confident, compared to Sprague Dawley rats: they showed better performance with longer time underwater and slower diving speed. We also uncover differences in their variability, at trial-to-trial intra-individual and population inter-individual levels, which can guide the choice of one strain over the other, depending on the aim of the scientific inquiry.

animal behavior and cognition↗

bioRxiv2024

Syngap1 regulates the synaptic drive and membrane excitability of Parvalbumin-positive interneurons in mouse auditory cortex

SYNGAP1 haploinsufficiency-related intellectual disability (SYNGAP1-ID) is characterized by moderate to severe ID, generalized epilepsy, autism spectrum disorder, sensory processing dysfunction and other behavioral abnormalities. While numerous studies have highlighted a role of Syngap1 in cortical excitatory neurons development, recent studies suggest that Syngap1 plays a role in GABAergic inhibitory neuron development as well. However, the molecular pathways by which Syngap1 acts on GABAergic neurons, and whether they are similar or different from the mechanisms underlying its effects in excitatory neurons, is unknown. Here, we examined whether, and how, embryonic-onset Syngap1 haploinsufficiency restricted to GABAergic interneurons derived from the medial ganglionic eminence (MGE) impacts their synaptic and intrinsic properties in adult primary auditory cortex (A1). We found that Syngap1 haploinsufficiency significantly affected the intrinsic properties, overall leading to increased firing threshold, and decreased excitatory synaptic drive of Parvalbumin (PV)+ neurons in adult Layer IV A1. Further, the AMPA component of thalamocortical evoked-EPSC was decreased in PV+ cells from mutant mice. Mutant somatostatin (SST)+ interneurons exhibited decreased spontaneous excitatory input and impaired evoked firing without alterations in firing threshold. Finally, we found that the selective blocking of voltage-gated D-type K+ currents was sufficient to rescue PV+ mutant cell-intrinsic properties to wild-type levels. Together, these data suggest that Syngap1 plays a specific role in the maturation of PV+ cell intrinsic properties and synaptic drive, and its haploinsufficiency may lead to reduced PV cell recruitment in the adult A1, which could in turn contribute to the auditory processing alterations found in SYNGAP1-ID preclinical models and patients.

neuroscience↗