BRAIN REGIONS INVOLVED IN SHIFTING ATTENTION BETWEEN GLOBAL AND LOCAL FEATURES OF VISUAL PATTERNS: A PET STUDY IN MACAQUE MONKEYS

Hide-Ki, Tanaka, Hirotaka, Onoe, Hideo, Tsukada and Ichiro, Fujita.
Department of Cognitive Neuroscience, Osaka University Medical School, Graduate School of Engineering Science, Osaka University, Core Research from Evolutionary Science and Technology (CREST), Japan Science and Technology Corporation (JST), Osaka, Department of Psychology, Tokyo Metropolitan Institute for Neuroscience, Tokyo, Central Research Laboratory, Hamamatsu Photonics, Shizuoka, Japan.

@@To identify brain areas involved in maintenance of attention and shifting of attention between global and local features of visual patterns, we applied positron emission tomography (PET) techniques to measure the regional cerebral blood flow (rCBF) in monkeys during a visual discrimination task. Visual stimuli were large letters (2.7 x 2.7 deg) made of a string of small letters (0.4 x 0.4 deg). Two monkeys (Macaca fuscata) were trained to detect a target (N or Z) which appeared pseudorandomly at either the global or the local level of the visual stimulus. The monkeys were supposed to shift their attention between the global and local features of the stimulus patterns when a sequence of trials changed between global and local trials. The number of target switches between the global and local levels (SW) was varied from 1 to 9 in the first 24-sec epoch of each PET scan. We identified brain areas whose rCBF changed with the SW using the SPM 95 software, and obtained the areas with the significant correlation in a consistent manner in the two monkeys. An increase in the rCBF in the posterior part of the lateral intraparietal (LIP) area was positively correlated with the SW. On the other hand, an increase in the rCBF in the medial frontal cortex (areas 14, 24 and 32) and the ventral part of cerebellar cortex were negatively correlated with the SW. The results suggest that area LIP is involved in shifting of attention between global and local levels of visual patterns, whereas the medial frontal areas and the ventral part of cerebellar cortex are involved in the maintenance of attention at one level. (supported by CREST)


Back