Article

Errors generate typical brain responses, characterized by two successive
event-related potentials (ERP) following incorrect action: the error-related
negativity (ERN) and the positivity error (Pe). However, it is unclear whether
these error-related responses are sensitive to the magnitude of the error, or
instead show all-or-none effects. We studied error-monitoring with ERPs while
healthy adult participants performed ballistic pointing movements towards a
visual target with or without optical prisms, in alternating runs. This allowed
us to record variable pointing errors, ranging from slight to large deviations
relative to the visual target. Behavioural results demonstrated a classic effect
of prisms on pointing (i.e. initial shifts away from targets, with rapidly
improving performance), as well as robust prismatic after-effects (i.e.
deviations in the opposite direction when removing the prisms after successful
adaptation). Critically, the amplitude of both ERN and Pe were strongly
influenced by the magnitude of errors. Error-related ERPs were observed for large
deviations, but their amplitudes decreased monotonically when pointing accuracy
increased, revealing a parametric modulation of monitoring systems as a function
of the severity of errors. These results indicate that early error detection
mechanisms do not represent failures in an all-or-none manner, but rather encode
the degree of mismatch between the actual and expected motor outcome, providing a
flexible cognitive control process that can discriminate between different
degrees of mismatch between intentions and outcomes.
CI - Copyright (c) 2011 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS