Contribution of dendritic integration properties to circuit computations
Nonlinear summation of synaptic potentials in dendrites is thought to increase computational power of neurons and has been shown to contribute to feature selectivity of neurons, but how dendritic computations of interneurons shape information flow within microcircuits is less well known. In the cerebellum, interneuron dendritic trees sample a fraction of the GC activity pattern driving PC activity. However, understanding how BC and SCs process this information and thus influence PC activity is not known. The aim of this project is to examine how dendritic properties tune nonlinear operations of synaptic voltage in order to perform cerebellar neuronal and circuit computations.
Abrahamsson, T., Cathala, L., Matsui, K., Shigemoto, R., and Digregorio, D.A. (2012). Thin dendrites of cerebellar interneurons confer sublinear synaptic integration and a gradient of short-term plasticity. Neuron 73, 1159-1172.
Tran-Van-Minh, A., Abrahamsson, T., Cathala, L., and DiGregorio, D.A. (2016). Differential Dendritic Integration of Synaptic Potentials and Calcium in Cerebellar Interneurons. Neuron 91, 837-850.
Vlasits, A.L., Morrie, R.D., Tran-Van-Minh, A., Bleckert, A., Gainer, C.F., DiGregorio, D.A., and Feller, M.B. (2016). A Role for Synaptic Input Distribution in a Dendritic Computation of Motion Direction in the Retina. Neuron 89, 1317-1330.
Summary: Nonlinear mathematical operations performed in dendritic trees are thought to be important for tuning of neuronal firing to specific pattern of synaptic inputs. We described one of the first examples of a sublinear dendritic voltage operation, and how cerebellar interneurons might use it to detect distributed spatial patterns of synaptic inputs(Abrahamsson et al., 2012). We also found this nonlinearity to be associated with an opposing, supralinear summation of intracellular [Ca2+] transients, which in turn regulates of synaptic strength and the neuron’s computation(Tran-Van-Minh et al., 2016). Finally, in retinal starburst amacrine neurons we showed how specific synaptic placement in the dendritic tree was critical for the encoding direction of movement(Vlasits et al., 2016), a fine example of cellular mechanisms of neuronal computations.