Learning and self-regulation of slow cortical potentials in older adults

Two groups of subjects, aged 20-28 and 50-64, respectively, matched for hea lth status and vel bal abilities, learned to control their slow cortical po tentials (SCP) in a feedback paradigm by producing, on command, SCP shifts in either positive or negative direction. Both groups were able to differen tiate significantly between the positivity task and rite negativity task, w ith the differentiate score being only slightly (and not significantly) low er in older than in younger subjects. In all conditions, however, significa ntly more negative brain responses were obtained in older than in younger s ubjects. This effect was larger in the positivity task versus negativity ta sk, and larger in trials without continuous SCP feedback versus trials with feedback. Additionally foul learning tasks were carried out with all subje cts. The older group demonstrated substantial performance deficits in two t asks with explicit learning (verbal and visual). In contrast, implicit lear ning (perceptual learning and skill acquisition) was not impaired with age. The results are at odds with the idea of general age-related learning defi cit and concur with the hypothesis that only explicit, hilt not implicit, l earning processes are compromised in older subjects. The pattern of consist ently more negative SCP shifts produced by elderly subjects may indicate th eir impaired cortical inhibition. Another interpretation, which does not ex clude the inhibitory deficit hypothesis but seems to better agree,with othe r psychophysiological data, may he that older subjects hare disturbance in the system controlling arousal and effort.