Effects of cortical polarization on mental arithmetic

Area of Science:

• Cognitive Neuroscience
• Neuropsychology
• Human Learning and Memory

Background:

• Understanding the neural mechanisms underlying cognitive processes like mental arithmetic is crucial.
• Slow cortical potentials (SCPs) are slow voltage changes in the brain's electrical activity, reflecting cortical excitability.
• Biofeedback offers a method to voluntarily control physiological states, including brain activity.

Purpose of the Study:

• To investigate the causal relationship between pre-stimulus cortical polarity and mental calculation performance.
• To determine if biofeedback-induced changes in cortical polarity affect response initiation and error rates in arithmetic tasks.

Main Methods:

• Participants underwent biofeedback training to modulate their slow cortical potential (SCP) polarity (positive or negative) before solving multiplication problems.
• A limited set of practiced single-digit multiplication problems was used to ensure reliance on direct memory retrieval.
• Response initiation time (mental calculation) and response execution time (motor speed) were measured, along with accuracy.

Main Results:

• Cortical positivity before problem presentation was linked to faster response initiation times for correct answers.
• Cortical positivity also correlated with a higher number of multiplication errors compared to cortical negativity.
• Motor response execution time remained unaffected by the induced cortical polarity.

Conclusions:

• Pre-task cortical positivity appears to facilitate direct retrieval of arithmetic facts, possibly by reducing inhibition of incorrect responses.
• This reduced inhibition, induced by positivity, leads to faster but less accurate performance.
• Cortical negativity may promote greater accuracy through enhanced inhibition, though potentially at the cost of speed.