Striatum

We are interested in studying the dynamics and information processing in the striatum, the main input structure in the basal ganglia. Several cortical regions project to the striatum where they target a class of inhibitory neurons, called the medium spiny neurons, which make up nearly 90% of all neurons. These neurons display a characteristic pattern of electrical activity: their membrane potential irregularly alternates between a depolarized "up-state" and a hyperpolarized "down-state" in response to cortical input. These neurons are organized in a densely-connected recurrent neural network and they also project to deeper structures in the basal ganglia to generate and control motivated actions. How this recurrent inhibition shapes the electrical activity in the striatum and influences the processing of cortical input is not understood. We have developed a biophysical model of the medium spiny neuron which we are using to understand network computations. The striatum also controls and receives input from midbrain dopaminergic neurons which release dopamine, a powerful and versatile modulator neuronal function. Aberrant dopaminergic signalling is a key contributor to several clinical disorders such as Parkinson's disease and schizophrenia. We are also interested in modeling the signal transduction events that underlie dopaminergic modulation of striatal activity and how it affects the computations performed by the striatum.

Figure 1: Schematic of potential recurrent connectivity in the striatum (Plenz, Trends Neurosci. (2003))

Figure 2: Striatal medium spiny neuroni (C.J. Wilson).

Figure 3: Model traces (top) and in vivo intracellular recordings (bottom) from a striatal medium spiny neuron (Wilson and Kawaguchi (1996) J. Neurosci. 16:2397).