Activation of dorsolateral prefrontal cortex in a dual neuropsychological screening test: an fMRI approach.
BACKGROUND
The Kana Pick-out Test (KPT), which uses Kana or Japanese symbols that represent syllables, requires parallel processing of discrete (pick-out) and continuous (reading) dual tasks. As a dual task, the KPT is thought to test working memory and executive function, particularly in the prefrontal cortex (PFC), and is widely used in Japan as a clinical screen for dementia. Nevertheless, there has been little neurological investigation into PFC activity during this test.


METHODS
We used functional magnetic resonance imaging (fMRI) to evaluate changes in the blood oxygenation level-dependent (BOLD) signal in young healthy adults during performance of a computerized KPT dual task (comprised of reading comprehension and picking out vowels) and compared it to its single task components (reading or vowel pick-out alone).


RESULTS
Behavioral performance of the KPT degraded compared to its single task components. Performance of the KPT markedly increased BOLD signal intensity in the PFC, and also activated sensorimotor, parietal association, and visual cortex areas. In conjunction analyses, bilateral BOLD signal in the dorsolateral PFC (Brodmann's areas 45, 46) was present only in the KPT.


CONCLUSIONS
Our results support the central bottleneck theory and suggest that the dorsolateral PFC is an important mediator of neural activity for both short-term storage and executive processes. Quantitative evaluation of the KPT with fMRI in healthy adults is the first step towards understanding the effects of aging or cognitive impairment on KPT performance.
Departments of Physiology & Neuroscience, Kanagawa Dental College, Yokosuka, Kanagawa, Japan. waits_11r@yahoo.co.jp
Atsumichi
A
Tachibana
J Adam
JA
Noah
Shaw
S
Bronner
Yumie
Y
Ono
Yoshiyuki
Y
Hirano
Masami
M
Niwa
Kazuko
K
Watanabe
Minoru
M
Onozuka
D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009483:Neuropsychological Tests; D010775:Photic Stimulation / Q000379:methods; D017397:Prefrontal Cortex / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D011932:Reading; D055815:Young Adult