Brigitte Rockstroh Boeken

Abstract Two studies served to examine behavioural effects of slow cortical potentials (SPs). SPs were manipulated by means of a biofeedback procedure. The ability of human subjects to alter SPs differentially between the two hemispheres - specifically over the lateral aspects of teh central sulcus - was tested by providing feedback ofthe SP difference betwrrn C3 and C4. In Expt. I, 21 of the 45 subjects produced hemispheric asymmetries of more than 2 μV between C3 and C4 on an average after 80 trials of analogue, continuous and immediate feedback. In Expt. II, SP changes were fed back digitally at the end of each trial. Within 120 trials, 20 of the 48 subjects reached the criterion of a minimum 2-μV difference in SPs between C3 and C4 on the average. Average differentiation remained significantly below the SP differentiations achieved for continuous feedback. Trials with feedback were followed by ‘task’ trials without feedback, during which subjects were still requested to produce SP changes but also had to complete a Either sensorimotor tasks (Expt. I) or forced choice handedness tasks (Expt. II) were presented to evaluate behavioural consequences of hemispheric SP differences. In subjects achieving the required SP differentiation it affected the behavioural output in agreement with the known functions of the respective cortical area.

Entgegen der bis ins letzte Jahrzehnt dominierenden Auffassung, dass die Verbindungen zwischen den Nervenzellen des Gehirns nach Ende der Gehirnreifung unveränderbar seien, wächst die Erkenntnis, dass sich das Gehirn in Abhängigkeit von Erfahrung kontinuierlich selbst organisiert und reorganisiert. Evidenz für diese These plastischer Repräsentationen in der Großhirnrinde des erwachsenen Menschen wird anhand von Studien mit nicht-invasiven bildgebenden Verfahren beispielhaft vermittelt.