dc.description.abstract | Inhibitory interneurons (INs) in the lateral geniculate nucleus (LGN) provide both axonal and dendritic GABA output to
thalamocortical relay cells (TCs). Distal parts of the IN dendrites often enter into complex arrangements known as triadic
synapses, where the IN dendrite plays a dual role as postsynaptic to retinal input and presynaptic to TC dendrites. Dendritic
GABA release can be triggered by retinal input, in a highly localized process that is functionally isolated from the soma, but
can also be triggered by somatically elicited Ca2+-spikes and possibly by backpropagating action potentials. Ca2+-spikes in
INs are predominantly mediated by T-type Ca2+-channels (T-channels). Due to the complex nature of the dendritic
signalling, the function of the IN is likely to depend critically on how T-channels are distributed over the somatodendritic
membrane (T-distribution). To study the relationship between the T-distribution and several IN response properties, we here
run a series of simulations where we vary the T-distribution in a multicompartmental IN model with a realistic morphology.
We find that the somatic response to somatic current injection is facilitated by a high T-channel density in the soma-region.
Conversely, a high T-channel density in the distal dendritic region is found to facilitate dendritic signalling in both the
outward direction (increases the response in distal dendrites to somatic input) and the inward direction (the soma responds
stronger to distal synaptic input). The real T-distribution is likely to reflect a compromise between several neural functions,
involving somatic response patterns and dendritic signalling. | nb_NO |