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Abstract:
Abstract: We applied Deep Brain Stimulation (DBS) to gain
insight into the causal role of subcortical brain structures in the
generation of sensorimotor acts. DBS, a newly developed
therapeutical method in Parkinson's disease (PD) treatment, allows
to switch on and off a focused structure within the basal ganglia
with high frequency electrical stimulation. The resulting
variations in subjects' behaviour demonstrate the causal role of
the manipulated brain structure on behaviour. Such information can
not be delivered with methods like functional Magnetic Resonance
Imagery and PET. PD patients performed four reaction time tasks,
which differed with respect to cognitive but not motor
requirements. Cognitive requirements were manipulated by inserting
additional cognitive processing stages (e.g., response selection,
dual-task coordination) into the basic information processing chain
of a simple reaction time task. DBS and levodopa-state of patients
were manipulated orthogonally (on versus off). The results show a
single substructure within the basal ganglia that is related to
motor and not cognitive or perceptual functions of the tasks. This
finding is in accordance with results of tracer and lesion studies
in monkeys that indicated the existence of separated substructures
within the basal ganglia, which are specialised for either motor,
cognitive or limbic functions.
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