Subregional Differences in Medium Spiny Neuron Intrinsic Excitability Properties between Nucleus Accumbens Core and...

Area of Science:

• Neuroscience
• Cellular Electrophysiology
• Reward System Research

Background:

• The nucleus accumbens (NAc) is crucial for reward and motivation.
• The NAc comprises distinct core and shell subregions, primarily composed of medium spiny neurons (MSNs).
• While morphological differences between core and shell MSNs are known, their intrinsic excitability differences are less understood.

Purpose of the Study:

• To investigate and compare the intrinsic excitability of MSNs in the NAc core versus the NAc shell.
• To determine if subregional differences in MSN excitability exist in naive and rewarded rats.

Main Methods:

• Whole-cell patch-clamp recordings were performed on NAc slices from male rats (naive and rewarded).
• Intrinsic properties of MSNs in the NAc core and shell were systematically measured and compared.

Main Results:

• MSNs in the NAc shell exhibited significantly higher excitability than those in the NAc core across both experimental groups.
• Shell MSNs displayed greater input resistance, lower cell capacitance, and increased sag compared to core MSNs.
• Shell MSNs had a lower action potential current threshold, generated more action potentials, and fired at a faster frequency than core MSNs.

Conclusions:

• Significant subregional differences in MSN intrinsic excitability exist between the NAc core and shell.
• These electrophysiological distinctions may underlie the differential roles of NAc subregions in reward learning.
• The findings provide a physiological basis for the known anatomical and functional divergence of NAc core and shell MSNs.