Modeling the motor striatum under Deep Brain Stimulation in normal and MPTP conditions.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• The striatum (STR) is a key input nucleus of the basal ganglia (BG), integrating cortical, subthalamic nucleus (STN), and external globus pallidus (GPe) inputs.
• Parkinson's disease (PD) is characterized by dopamine (DA) depletion in the STR, significantly impacting motor control.
• The precise role of STR neuronal activity in PD and under Deep Brain Stimulation (DBS) remains incompletely understood.

Purpose of the Study:

• To develop computational models of STR neurons.
• To investigate the effects of dopamine depletion and STN DBS on STR neuronal activity and network dynamics.

Main Methods:

• Development of point-process models for STR neurons.
• Analysis of single-unit recordings from a non-human primate model.
• Experimental manipulation using 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine (MPTP) to induce PD-like symptoms.
• Application of STN DBS at varying frequencies.

Main Results:

• Normal STR neurons exhibit bursting activity, positive correlation with cortical input (3-10 ms delay), and negative correlation with GPe input (1-5 ms lag).
• Dopamine depletion induces 30-60 Hz oscillations and increases neuronal inhibition.
• STN DBS causes antidromic activation, masks intrinsic dynamics, strengthens inter-nuclear dependencies, and synchronizes activity to the stimulation frequency.

Conclusions:

• STR neuronal dynamics are significantly altered by dopamine depletion, leading to oscillatory activity and increased inhibition.
• STN DBS profoundly impacts STR function by disrupting normal processing, reinforcing network connections, and imposing stimulation-driven oscillations.
• These findings provide insights into the neural mechanisms underlying PD motor symptoms and the effects of DBS therapy.