Resource allocation and somatosensory P300 amplitude during dual task: effects of tracking speed and predictability of tracking direction.
OBJECTIVE
The amount of attentional resources allocated to a task is determined by the intrinsic demands, also denoted as task load or difficulty of the task. Effects of resource allocation on the somatosensory N140 and P300 were investigated in an inter-modal situation using a dual-task methodology.


METHODS
Under a dual-task condition, subjects concurrently performed a visuomotor tracking task and a somatosensory oddball task, while they performed just the oddball task under an oddball-only condition. In the tracking task, the subjects tracked the target line, which was presented on an oscilloscope and automatically moved, with the line which represented their own force generated by grip movement with the left hand. Tracking speed (experiment 1) and tracking predictability (experiment 2) were manipulated to vary task difficulty. N140, P300, and reaction time (RT) in the oddball task and tracking accuracy in the tracking task were measured.


RESULTS
The P300 and N140 amplitudes were reduced in the dual-task condition compared to those in the oddball-only condition. The fastest tracking speed produced lower tracking accuracy and later RT. However, the tracking speed did not affect the P300 or N140 amplitudes. In contrast, the P300 amplitude was smaller when the change in tracking direction was unpredictable than when it was predictable, without any differences in tracking accuracy or RT, N140.


CONCLUSIONS
The differences in behaviors among N140, P300, and RT following manipulation of task difficulty support the multiple-resource hypothesis, which defines functionally separate pools of resources.


CONCLUSIONS
The present study may show that the P300 amplitude reflects modality-unspecific resource at more central level, and that the N140 amplitude involves perceptual resource.
Doctoral Program in Health and Sports Sciences, Department of Physiology, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8574, Japan. nikita@seiri.taiiku.tsukuba.ac.jp
Tetsuo
T
Kida
Yoshiaki
Y
Nishihira
Arihiro
A
Hatta
Toshiaki
T
Wasaka
Toshiki
T
Tazoe
Yukie
Y
Sakajiri
Hiroki
H
Nakata
Takeshi
T
Kaneda
Kazuo
K
Kuroiwa
Sachiyo
S
Akiyama
Masanori
M
Sakamoto
Keita
K
Kamijo
Takuroh
T
Higashiura
D000328:Adult; D001288:Attention / Q000502:physiology*; D004558:Electric Stimulation; D018913:Event-Related Potentials, P300; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time; D012677:Sensation / Q000502:physiology*