Break-up and recovery of harmony between direct and indirect pathways in the basal ganglia: Huntington’s disease and treatment

Functions of Direct and Indirect Pathways for Action Selection Are Quantitatively Analyzed in A Spiking Neural Network of The Basal Ganglia

“…In the present work, we investigated action selection in the healthy state with harmony between DP and IP for the normal DA level ( ϕ = 0.3). But, through break-up of their harmony, pathological states such as Parkinson’s disease (PD) and Huntington’s disease (HD) occur [35, 36]. Due to deficiency in DA (i.e.…”

“…We consider an SNN with 3 laterally interconnected channels for action selection in the BG [7, 11]. Here, each single channel is the same as that considered in our prior works [35, 36]. The SNN with a single channel is founded on anatomical and physiological data obtained in rat-based works.…”

“…1(b). Here, we also consider a healthy state for a normal DA level ( ϕ = 0.3), and make quantitative analysis of functions of the DP and the two intra- and inter-channel IPs by employing the competition degree 𝒞 d (characterizing competitive harmony between DP and IP) [35, 36]. Through calculations of the DP and the intra- and inter-channel IP synaptic currents into the SNr in each channel, we get the competition degree 𝒞 d of each channel to determine a desired action.…”

“…In this paper, we pay attention to action selection performed by the BG in a spiking neural network (SNN) of the BG with 3 laterally interconnected channels; each channel represents an action. We employ the same SNN with the single channel as that considered in our prior works [35, 36]. Each single channel takes excitatory in-put from most areas of cortex through the input nuclei [striatum and subthalamic nucleus (STN)] and provide inhibitory output via the output nucleus [substantia nigra pars reticulata (SNr)] to the thalamus/brainstem [7, 10, 11].…”

“…But, to the best of our knowledge, no quantitative analysis for the functions of the DP and the two intra- and inter-channel IPs was made. In this paper, we make quantitative analysis of functions of DP and IP for action selection, based on the recently-introduced competition degree 𝒞 d (making characterization of competitive harmony between DP and IP) [35, 36]. Through computations of the DP and the intra- and inter-channel IP synaptic currents into the SNr in each channel, we obtain the competition degree 𝒞 d of each channel to determine a desired action.…”