Neuronal Dynamics of The Basal Ganglia and Related Systems

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Terman0103822 The investigator and his colleague develop geometric,dynamical systems tools for analyzing biophysical,conductance-based models for a broad class of neuronal networks.These systems arise in numerous applications including motoractivity, sensory processing and learning. They also developcomputational models for the generation of sleep rhythms,epilepsy and parkinsonian tremor. The investigators alsoconstruct and refine a mathematical and computational model forelectrical activity in the subthalamic nucleus and externalsegment of the globus pallidus. These are two nuclei in thebasal ganglia, a part of the brain involved in motor activity.Dysfunction of the basal ganglia is associated with movementdisorders such as Parkinson's disease and Huntington's disease.The model is used to test hypotheses on the role of the basalganglia in both normal and pathological movement. Numerousexperiments have demonstrated that neurons within the basalganglia display a rich variety of dynamic behavior; moreover,patterns of neuronal activity, both spatial and temporal, aredifferent between a normal and a pathological state. Theinvestigators characterize the possible patterns of neuronalactivity that arise in the model and determine how these patternschange with respect to modulations of network parameters andstructure. A long term goal is to develop a model realisticenough so that it can shed light upon the key parameters andmechanisms responsible for the generation and modulation ofobserved activity patterns. A mathematical theory for the analysis of neuronal dynamicshelps illuminate the role played by various components of a modelin generating a particular population rhythm. These componentsmay correspond to some intrinsic property of individual cells, orto some network property such as the strength and type ofsynaptic coupling or the probability that two cells communicatewith each other. Clarification of the mechanisms underlyingdifferent activity patterns may lead to a classification of allpossible rhythms that can emerge from a given network, and enableus to determine how complicated a model should be in order todisplay some observed behavior. It also helps predicttransitions of the network behavior as parameters in the modelare varied. The investigators develop models for neuronaldynamics, and in particular of electrical activity in thesubthalamic nucleus and external segment of the globus pallidus.These are two nuclei in the basal ganglia, a part of the braininvolved in motor activity. Dysfunction of the basal ganglia isassociated with movement disorders such as Parkinson's diseaseand Huntington's disease. The model is used to test hypotheseson the role of the basal ganglia in both normal and pathologicalmovement. Such models may help illuminate both fundamentalneuroscience questions and clinical issues about how the brainand central nervous system work.