Tracking progress toward a goal in corticostriatal ensembles.

Area of Science:

• Neuroscience
• Cognitive Science
• Computational Neuroscience

Background:

• Maintaining an internal representation of progress through action sequences is crucial for goal-directed behavior.
• Corticostriatal circuits are implicated in motor control, learning, and decision-making, making them key areas to investigate sequence representation.

Purpose of the Study:

• To investigate how neural ensembles in the anterior cingulate cortex (ACC) and dorsal striatum (DS) represent progression through action sequences.
• To differentiate between neural signals encoding overall sequence progress versus individual action execution within corticostriatal circuits.

Main Methods:

• Simultaneous electrophysiological recordings from ACC and DS neurons in rats performing lever-press sequences.
• Analysis of neuronal firing rates based on the serial position (first, second, third) within action sequences.
• Principal component analysis (PCA) to identify dominant patterns of neural activity variance.

Main Results:

• ACC neuronal ensembles exhibited a smooth, ramp-like increase in firing rate as a function of sequence progression toward the goal.
• DS neuronal ensembles showed firing patterns tightly linked to individual lever presses, irrespective of their serial position.
• ACC ramping activity was specific to correct action sequences, whereas DS activity reflected all actions, correct or incorrect.

Conclusions:

• The ACC encodes abstract representations of sequence progress, signaling advancement toward a goal.
• The DS encodes a more detailed representation, tracking each individual action within a sequence.
• Distinct neural mechanisms within corticostriatal circuits contribute to the representation of sequential actions and progress toward goals.