Activity-dependent modulation of inhibitory synaptic kinetics in the cochlear nucleus

What is it about?

Spherical bushy cells (SBCs) in a part of the brain that processes sound exhibit electrical activity with very precise timing. This precise timing is crucial for tasks like figuring out where a sound is coming from or understanding speech. To achieve this precision, SBCs rely on the interaction of activation (excitation) and suppression (inhibition). Given the need for temporal precision, the inhibition was initially thought to be very fast, but recent research shows that things are a bit more complicated. During development, inhibition shifts from using one type of neurotransmitter, glycine, to a mix of glycine and another one called GABA, depending on how active the nerve cells are. At the same time, this inhibition becomes gradually slower as the animal matures and transforms into a more continuous, almost constant signal. In this study, we wanted to understand why this inhibition behaves this way. We recorded the electrical activity of SBCs of young gerbils and looked at the inhibition at normal activity levels. What we found was that the inhibition's speed depends on how much of the chemicals are released with less release increasing the speed of inhibition. This suggests that the neurotransmitters remain in the area between cells (synaptic cleft) for longer, making the signal last longer. This longer-lasting signal then helps to regulate the electrical activity of SBCs, which is important for their precise timing.

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