Activation of dorsolateral prefrontal cortex in a dual neuropsychological screening test: An fMRI approach

doi:10.1186/1744-9081-8-26

Behav Brain Funct. 2012; 8: 26.

Published online 2012 May 28. doi: 10.1186/1744-9081-8-26

PMCID: PMC3464709

Activation of dorsolateral prefrontal cortex in a dual neuropsychological screening test: An fMRI approach

Atsumichi Tachibana,^1,^2,^3,⁷ J Adam Noah,³ Shaw Bronner,³ Yumie Ono,^1,^2,⁴ Yoshiyuki Hirano,^2,⁵ Masami Niwa,^2,⁶ Kazuko Watanabe,^2,⁷ and Minoru Onozuka^1,²

¹Departments of Physiology & Neuroscience, Kanagawa Dental College, Yokosuka, Kanagawa, Japan

²Research Center of Brain & Oral Sciences, Kanagawa Dental College, Yokosuka, Kanagawa, Japan

³ADAM Center, Long Island University, Brooklyn, NY, USA

⁴Department of Electronics and Bioinformatics, School of Science and Technology, Meiji University, Kawasaki, Kanagawa, Japan

⁵Research Center for Child Mental Development, Chiba University Graduate School of Medicine, Chiba, Chiba, Japan

⁶Department of Radiology, Tohno Welfare Hospital, Mizunami, Japan

⁷Faculty of Care and Rehabilitation (Physiology), Seijoh University, Tohkai, Aichi, Japan

Corresponding author.

Atsumichi Tachibana: waits_11r/at/yahoo.co.jp; J Adam Noah: adam/at/adamnoah.com; Shaw Bronner: sbronner/at/liu.edu; Yumie Ono: yumie/at/meiji.ac.jp; Yoshiyuki Hirano: hirano/at/chiba-u.jp; Masami Niwa: m7niwa/at/poem.ocn.ne.jp; Kazuko Watanabe: watanabe/at/seijoh-u.ac.jp; Minoru Onozuka: onozuka/at/kdcnet.ac.jp

Received September 30, 2011; Accepted May 28, 2012.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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.

Keywords: Executive function, Neuropsychological test, Working memory

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