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Abstract:
Abstract: People engaging in novel physical or mental
activity often experience hallucinatory replay of the activities at
sleep onset. We studied this phenomenon in normal and densely
amnesic subjects using the computer game Tetris. During the nights
following three days of play, subjects were prompted for mentation
reports during the first hour of sleep. Seventeen of 22 normal
subjects (63%) reported a total of 30 intrusive hypnagogic Tetris
images (7.2% of all reports). The occurrence of imagery correlated
with poorer performance during the initial 2-hr training session.
Images were stereotyped, consisting of visual images of the Tetris
pieces. Two experts consistently reported images of their
previously played version of the game, not the version used in the
experiment. Surprisingly, 3 of 5 dense non-Koraskoff's amnesiacs,
with extensive bilateral hippocampal and medial temporal lobe
damage, reported a total of 8 hypnagogic Tetris images. The
percents of subjects (60%) and reports (7.4%) were very similar to
normals, but patients reported the images without recollection of
playing the game. We conclude that amnesiacs and normals alike
created these hypnagogic Tetris images using cortical memory
systems, without participation of the hippocampus or other medial
temporal lobe structures. These findings further suggest that
hypnagogic dream images arise in conjunction with a sleep-dependent
process of cortical memory consolidation and integration.
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