Regular articleSpatiotemporal characteristics of hemodynamic changes in the human lateral prefrontal cortex during working memory tasks
Section snippets
Participants
Twelve right-handed paid volunteers (age range, 21–29, male 11, female 1) participated in this study. None had a history of neurological illness, head injury, or substance abuse. Prior to each study, written informed consent was obtained from all participants. All participants were given practice with the tasks.
Near-infrared spectroscopy instruments
A multichannel NIRS imaging system (OMM-2000, Shimadzu Co.) and a single-channel time-resolved spectroscopy instrument (TRS-10, Hamamatsu Photonics KK) were employed. Three wavelengths
Task performance
As is typical with simple cognitive tasks, the mean responses accuracy was high and the distribution of scores was negatively skewed. Accuracies for the 1-, 2-, and 3-back tasks were 98 ± 4.01 (mean ± SD), 93 ± 8, and 83 ± 24%, respectively, while two participants showed extremely poor task performance in the 3-back task (Table 2). Randomness was evaluated by counting bias (CA, the tendency to count in ascending or descending series in steps of 1), interval bias (IB, the tendency to produce
Spatial characteristics
It is thought that the n-back task requires manipulations and monitoring in addition to active maintenance, and it has been reported that both the VLPFC and the DLPFC are activated during performance of the verbal n-back task Braver et al., 1997, D'Esposito et al., 1998. However, the present study has demonstrated that the VLPFC mainly contributes to the n-back task. This might be explained by the fact that once participants find a strategy, they can automatically perform even the 3-back task,
Conclusion
Much theoretical and experimental work has combined to suggest specific loci and roles for working memory processes in the frontal cortex. Although our study supports some functional segregation, two different working memory tasks selectively activated different regions in the PFC, it also demonstrated that there are overlaps in brain activations across the tasks in each participant. However, our data on nonsustained activation and differences in commonly activated areas between participants
Acknowledgements
This study was partially funded by the Asian Office of Aerospace Research and Development, Tokyo, Japan.
References (33)
- et al.
A parametric study of prefrontal cortex involvement in human working memory
NeuroImage
(1997) - et al.
Regional brain activity during tasks devoted to the central executive of working memory
Cogn. Brain Res.
(1999) - et al.
Brain imaging of the central executive component of working memory
Neurosci. Biobehav. Rev.
(2002) - et al.
Functional MRI studies of spatial and nonspatial working memory
Cogn. Brain Res.
(1998) - et al.
Common regions of the human frontal lobe recruited by diverse cognitive demands
Trends Neurosci.
(2000) - et al.
Detection of dynamic changes in cerebral oxygenation coupled to neuronal function during mental work in man
Neurosci. Lett
(1993) - et al.
The role of the dorsolateral prefrontal cortex in random number generationa study with positron emission tomography
NeuroImage
(2000) - et al.
Near-infrared spectroscopy (NIRS)a new tool to study hemodynamic changes during activation of brain function in human adults
Neurosci. Lett.
(1993) Working memory
(1986)The central executivea concept and some misconceptions
J. Int. Neuropsychol. Soc.
(1998)
Working memory
Determionation of language dominance using functional MRIa comparison with the Wada test
Neurology
Temporal dynamics of brain activation during a working memory task
Nature
The role of prefrontal cortex in working memoryexamining the contents of consciousness
Philos. Trans. R. Soc. London Ser. B
Cortical areas and the selection of movementa study with positron emission tomography
Exp. Brain Res.
Estimation of optical pathlength through tissue from direct time of flight measurement
Phys. Med. Biol.
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