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Abstract:
Abstract: This study investigated whether word processing can
specifically be modified by learned changes of electrocortical
activity in aphasic patients and in healthy controls. Six aphasic
patients with mild to severe language impairment and 12 normal
controls received feedback of slow cortical potential (SCP) shifts
recorded above either the right or left hemisphere. Study
participants were reinforced for producing alterations of brain
potentials either towards "negativity" or "positivity" upon two
discriminative stimuli. Before and after SCP-training, verbal and
nonverbal tasks were applied. All patients successfully learned to
control their SCPs. After training, patients showed significantly
faster reactions in a lexical decision task only in the
"negativity" condition compared to "positivity" condition. Only six
normal controls achieved reliable control over SCPs (learners).
Learners, like aphasics, demonstrated significant speeding of
lexical decisions only in the "negativity" condition after
training. In aphasics and in normals, learned SCP changes did not
affect nonverbal processing. Non-learners did not show any
difference in verbal or nonverbal tasks after training. Learned
changes of SCPs can modulate word processing in aphasics and
normals. Only the condition in which brain potentials are more
negative-going and in which the brain is probably in a more
"active" state leads to speeding of verbal processing. We conclude
that SCP-training may serve as a useful tool in aphasia
therapy.
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