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Abstract:
This study investigated the functional damage associated with
diffuse brain injury. Thirteen patients were selected on the basis
of mild to severe difficulties in concentration, task set and
memory. High-density EEG recording was performed while patients and
16 control subjects were engaged in five tasks involving various
forms of attention and working memory. Functional impairments of
the three major attention networks-vigilance, sensory orienting,
and executive control- were investigated using the Continuous
Performance Task (CPT), the covert orienting task, and the Stroop
task. Sternberg's memory task was used to investigate verbal and
spatial working memory. Patients showed a general slowing in
response latencies and a reduced amplitude of endogenous Event
Related Potentials (ERPs). Sensory orienting functions appeared
intact in ABI patients. The CPT results revealed impaired vigilance
in patients and a specific deficit in using prior information to
select the target. In the Stroop task, patients showed larger
interference from the irrelevant color-words and abnormal
electrical activity in midline electrodes that in normals has been
associated with cingulate gyrus' activation. Patients were highly
impaired in the working memory tasks and showed almost no effect of
memory load in the ERP waveforms. In conclusion, ABI patients
showed specific deficits in executive control and working memory,
suggesting that the most remarkable effect of diffuse brain injury
is functional impairment of frontal areas.
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