Time-dependent changes in human corticospinal excitability reveal value-based competition for action during decision...

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Decision Science

Background:

• The neural basis linking decision-making and action selection is not fully understood.
• Current theories suggest action selection and decision processes may occur in parallel.
• Value computations are hypothesized to bias action selection in motor regions.

Purpose of the Study:

• To investigate the temporal relationship between value-based decision-making and action selection.
• To find physiological evidence for biases in motor cortex during decision formation.
• To test if motor system activity reflects choice value before decision completion.

Main Methods:

• Utilized transcranial magnetic stimulation (TMS) to measure corticospinal excitability.
• Recorded changes in motor cortex excitability during value-based decision tasks in humans.
• Analyzed reaction times and TMS measures in relation to subjective action values.

Main Results:

• Corticospinal excitability distinguished between chosen and unchosen actions before decision completion.
• Both excitability and reaction times correlated with the subjective value difference between options.
• This value-driven effect on motor cortex excitability was absent when no decision was required.

Conclusions:

• Provides direct physiological evidence that value-based decisions influence motor cortex competition before a choice is finalized.
• Supports models of parallel processing in decision-making and action selection.
• Challenges serial models where action selection follows complete stimulus evaluation and decision.