Biology

Dr. Arvind Kumar
KTH Royal Institute of Technology, Stockholm

Subcortical brain structure such as the basal ganglia and the amygdala are crucial for a variety of decision-making and emotional functions. Basal ganglia is organised as a network of three purely inhibitory sub-networks. Amygdala also has a similar network organization. Two interesting properties of the dynamics of inhibitory networks in the subcortical regions have recently become apparent:
(1) Almost all inhibitory sub-networks are organised as two population networks and both populations maintain comparable firing rates. This is particularly surprising because one population exerts more inhibition on the other.
(2) In behaving animals neighbouring neurons become co-active forming spatially compact transient neuronal assemblies, which may also form temporal sequences. How inhibitory network can generate such spatially compact transient neuronal assemblies is not well understood.

In my talk I will discuss these two properties of the inhibitory dynamics and propose the condition under which (1) two mutually inhibitory populations can maintain comparable firing rates and (2) show spatially compact neuronal assemblies. Specifically, I will argue that inhibitory networks can show spatially compact neuronal assemblies only when the recurrent connectivity changes non monotonically as a function of distance. Finally, I will discuss the implications of the inhibitory dynamics for brain function (decision-making) and dysfunction in particular Parkinson’s disease.