Key result
The TS2 mutation in mice led to widened action potentials, increased PV+ cell density, and altered neuronal responses to visual stimuli compared to wild-type mice.
Why the study?
Timothy syndrome causes serious cardiac and neurological symptoms, but the effects of Timothy syndrome mutations on neuronal function in vivo are not fully understood.
Does the TS2-neo mutation alter primary visual cortex physiology and function in a mouse model of Timothy Syndrome?
Does the TS2-neo mutation alter primary visual cortex physiology and function in a mouse model of Timothy Syndrome?
The TS2-neo mutation in a mouse model of Timothy Syndrome leads to prolonged action potentials and altered visual contrast sensitivity, pointing to basic sensory processing abnormalities in the visual cortex.
Hypothesis-generating for visual cortex dysfunction in Timothy syndrome; leaves open human translation and therapeutic relevance.
Timothy syndrome (TS) is a rare genetic disorder caused by mutations in the CACNA1C gene which encodes the L-type calcium channel α-1 CaV1.2 subunit. While it is expressed throughout the body the most serious symptoms are cardiac and neurological. Classical TS1 and TS2 mutations cause prolonged action potentials (APs) in cardiomyocytes and in induced neurons derived from pluripotent stem cells taken from TS patients, but effects of TS mutations on neuronal function in vivo are not fully understood. TS is frequently associated with autistic traits, which in turn have been linked to altered sensory processing. Using the TS2-neo mouse model we analysed effects of the TS2 mutation on the visual system. We observed a widening of APs of pyramidal cells in ex vivo patch-clamp recordings and an increase in the density of parvalbumin positive (PV+) cells in the primary visual cortex. Neurons recorded extracellularly in vivo were less likely to respond to visual stimuli of low spatial frequency, but more likely to respond to visual stimuli of mid-to-high spatial frequency, compared to WT mice. These results point to a basic processing abnormality in the visual cortex of TS2-neo mice.
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Craddock et al. (2024) studied Timothy syndrome. TS2 mutation vs. Wild-type (WT) mice was evaluated on Action potential duration, PV+ cell density, and neuronal response to visual stimuli. The TS2 mutation in mice led to widened action potentials, increased PV+ cell density, and altered neuronal responses to visual stimuli compared to wild-type mice.
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