Bypassing use-dependent plasticity in the primary motor cortex to preserve adaptive behavior.

Behavioral adaptation, a central feature of voluntary movement, is known to rely on top-down cognitive control. For example, the conflict-adaptation effect on tasks such as the Stroop task leads to better performance (e.g. shorter reaction time) for incongruent trials following an already incongruent one. The role of higher-order cortices in such between-trial adjustments is well documented, however, a specific involvement of the primary motor cortex (M1) has seldom been questioned. Here we studied changes in corticospinal excitability associated with the conflict-adaptation process. For this, we used single-pulse transcranial-magnetic stimulation (TMS) applied between two consecutive trials in an interference flanker task, while measuring motor-evoked potentials (MEPs) after agonistic and antagonistic voluntary movements. In agonist movement, MEP amplitude was modulated by recent movement history with an increase favoring movement repetition, but no significant change in MEP size was observed whether a previous trial was incongruent or congruent. Critically, for an antagonist movement, the relative size of MEPs following incongruent trials correlated positively with the strength of behavioral adaptation measured as the degree of RT shortening across subjects. This post-conflict increase in corticospinal excitability related to antagonist muscle recruitment could compensate for a potential deleterious bias due to recent movement history that favors the last executed action. Namely, it prepares the motor system to rapidly adapt to a changing and unpredictable context by equalizing the preparation for all possible motor responses.

The anterior midcingulate cortex might be a neuronal substrate for the ideomotor mechanism.

The way the brain controls voluntary movements for normal and pathological subject remains puzzling. In this selective review, we provide unreported harmonies between the anterior midcingulate cortex (aMCC) activities and the ideomotor mechanism postulating that voluntary movements are controlled by the anticipation of the expected perceptual consequences of an action, critically involving bidirectional interplay of a given motor activity and corresponding sensory feedback. Among other evidence, we found that the required asymmetry in the bidirectional interplay between a given motor command and its expected sensory effect could rely on the specific activity of aMCC neurons when observing errors and successes. We confirm this hypothesis by presenting a pathological perspective, studying obsessive-compulsive and other related disorders in which hyperactivated and uniform aMCC activities should lead to a circular-reflex process that results in persistent ideas and repeated actions. By evaluating normal and pathological data, we propose considering the aMCC at a central position within the cerebral network involved in the ideomotor mechanism.

[Do physicians know if their patients are satisfied? A study in general practice carried out by medical students]. / Vet legen om pasienten er tilfreds? En studentundersøkelse utført i allmennpraksis.

A doctor's ability to assess to what degree his patients are satisfied may indicate how well the patient and the doctor communicate. The main intention of this study was to evaluate the doctor's ability to register a patient's level of satisfaction after a consultation. 19 doctors from six medical centres in Eastern Norway participated. In 50% of the 216 consultations the doctors were able to state exactly how satisfied the patients were. In most of the cases with a mismatch between the doctor's and his patient's ratings the patients were more satisfied than the doctors realized. In some of these cases, however, the doctors failed to observe that the patients were dissatisfied. Male doctors were able to state the patients' level of satisfaction more accurately than female doctors were. Doctors with more experience were also more accurate in their assessments. The method of research used in this area can be problematic. A more reliable and valid questionnaire should be developed.