Cortical processing of flexible and context-dependent sensorimotor sequences

Area of Science:

• Neuroscience
• Motor Control
• Computational Neuroscience

Background:

• The brain's ability to generate flexible and context-dependent movement sequences is crucial for behavior.
• Understanding the neural mechanisms underlying sequential movement generation, especially with real-time adjustments, remains a challenge.

Purpose of the Study:

• To investigate the neural basis of flexible, context-informed sequential movement generation in the mammalian brain.
• To elucidate the distinct roles of different cortical areas in controlling and encoding complex motor sequences.

Main Methods:

• Development of a 'sequence licking' task where mice navigate a moving target with their tongue.
• Utilized closed-loop optogenetics and electrophysiology to record and manipulate neural activity.
• Analysis of neural encoding of kinematic parameters and latent behavioral variables.

Main Results:

• Primary somatosensory (S1TJ) and motor (M1TJ) cortices precisely encode and control individual tongue lick kinematics.
• The anterolateral motor cortex (tongue premotor cortex) encodes abstract variables like intended lick angle and sequence progress.
• Movement-nonspecific branching signals were observed in both anterolateral motor cortex and M1TJ.

Conclusions:

• Distinct cortical areas play specialized roles in generating flexible motor sequences.
• S1TJ and M1TJ are critical for the execution of fine-grained tongue movements.
• The anterolateral motor cortex contributes to higher-level planning and contextual modulation of movement sequences.