Striatal network modeling in Huntington's Disease.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Medium spiny neurons (MSNs) are the primary cell type in the striatum, crucial for action sequence learning.
• In vivo, MSNs exhibit coordinated burst firing, yet lack intrinsic bursting, suggesting network-level mechanisms.
• This activity is impaired in Huntington's Disease (HD), but the underlying neural circuit alterations remain unclear.

Purpose of the Study:

• To investigate the network dynamics of medium spiny neurons (MSNs) in wild-type (WT) and Huntington's Disease (HD) models.
• To identify specific alterations in MSN network parameters that contribute to HD pathophysiology.
• To understand how these network changes lead to aberrant neural activity and HD symptoms.

Main Methods:

• Developed a physiologically detailed MSN network model.
• Estimated network parameters directly from single-unit spiking data in WT and HD mouse models (YAC128, Q175, R6/2).
• Analyzed network dynamics and sensitivity to cortical input.

Main Results:

• The WT MSN network operates near a critical transition, enabling coherent activity and sensitivity to external drive.
• HD models consistently show reduced feedforward excitation and altered recurrent inhibition compared to WT.
• These parameter changes shift the HD MSN network to a regime dominated by high-dimensional, incoherent, fluctuating activity.

Conclusions:

• HD-induced changes in MSN network parameters disrupt normal neural dynamics, leading to aberrant activity patterns.
• The findings provide a mechanistic link between MSN network dysfunction and HD's cognitive and motor symptoms.
• This research may guide the development of novel therapeutic strategies for Huntington's Disease.