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Abstract:
We investigated the mechanism of abnormal time experience and
its neural correlates by studying the recovery process in a patient
who suffered from functional amnesia. A 24-year old female who
showed decelerated time experience and anterograde amnesia was
examined during and after her episode. She experienced external
events as seeming to occur at a much slower rate and reported loss
of temporal tag of past events. FDG-PET showed hypomatabolism in
the left thalamus during her episode. Neuropsychological
examinations revealed severe delayed memory deficit, with in tact
intellectual and frontal functions. She also showed the superior
perfor mances on digit span tasks (forward 8, backward 7),
indicating her increased attentional capacity. Prospective time
estimation tasks demonstrated overes timation for duration, while
time production tasks showed shortened time production, which
correspond to decelerated time experience. These impairments
improved after a year. PET study demonstrated improvements in
glucose metabolism in the bilateral thalamic and frontal regions.
Most possible explanat ion for her decelerated time experience is
increased attentional resources allocated to time, which allows
more pulses generated by a pacemaker to pass through to a
accumulator. Thalamofrontal system may be involved in the
allocation of attentional resources to time.
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