Sacha Albada

"Mean-field modeling of the basal ganglia-thalamocortical system"

The basal ganglia are a group of grey matter structures forming dense interconnections with the cortex and thalamus. They are involved in the selection and facilitation of motor programs, as well as procedural and reinforcement learning. Abnormalities in the basal ganglia are associated with disorders including Parkinson's disease, Huntington's disease, and schizophrenia. In Parkinson's disease, neurons in the substantia nigra pars compacta degenerate, leading to a loss of dopamine in the striatum. This causes changes in firing rates and patterns throughout the basal ganglia-thalamocortical system, including the vappearance of synchronized oscillations at 3-8 Hz and 10-25 Hz. These changes are thought to be responsible for parkinsonian motor symptoms, which include difficulty initiating movements, slowness of movement, and rest tremor. However, the mechanisms underlying changes in firing rates and patterns are not well understood.

We present a mean-field model of the basal ganglia-thalamocortical system that is based on an earlier model including only the thalamus and cortex. In this model, we can simulate the effects of dopamine loss by altering corticostriatal connection strengths. We show that an increase in the connection strength to a population of striatal neurons can lead not only to realistic changes in firing rates relative to the healthy state, but also to slow oscillations and enhanced synchronization in the basal ganglia.