Neurophysiological and behavioural changes during mental work in children with Down's syndrome.

Telemetered EEG and ECG were recorded from 18 Down's syndrome children (5;6--11 years) during rest, a visuomotor and a cognitive test, exploration and play. Simultaneously the behaviour was observed and recorded. In comparison with normal children (3;9--5;5 y. resp. 5;6--7;6 y.) the Down's syndrome children showed a low degree of motor activity, reduced attention and exploration and little variation of heart rate in relation to test difficulty. The main findings in the EEG (parieto-occipital recording) were a low amount and a small variability of alpha waves and a high amount of beta waves. This EEG phenomenon which is obviously not due to high activation is discussed with regard to possible connections with defective neurophysiological mechanisms of attention.