Brain activation during picture-word association encoding — An fMRI study

S266

583

BRAIN ACTIVATION

DURING PICTURE-WORD

RUITING XIAOQ, TOSHIMIZU TAKAHASHIQ, KENJI KAWANOi and TOSHIO IIJIMA’ iElectrotechnica1 Laboratory, Tsukuba 3058568, School of Med., Sendai 980-8575 To investigate activation

the functional

during encoding

picture encoding

them. In the picture-word

association

words separately,

encoding

formation

and bilateral

tasks, but the activation

hippocampus

encoding

might participate

processes,

national ensigns

individually

between

slight stronger

3Tohoku Univ.

we measured

human

brain

In the individual

and were asked to remember

with national ensigns and national names in

Before this task, the subjects were presented

parahippocampal

appeared

memory

332-0012,

pairs to memory by a 3T-fMR1 system.

task, subjects were presented

their associations.

but they did not know relationships

right hippocampal

in association

with unfamiliar

- AN fMR1 STUDY

INASE’, TAKASHI TSUKIURA’s3,

pictures and picture-word

task, subjects were presented

ENCODING

ZJapan Science & Technology Co., Kawaguchi

role of hippocampus

individual

pairs and were asked to remember

MASAHIKO

ASSOCIATION

the national ensigns

gyrus were observed

with these pictures and

and names. Significant in both the individual

activation

in the latter case than in the former case. It indicates

in memory process of picture-word

associations

of

and associative that

as well as in memory process of individual

pictures, but with different degrees of contributions. NEUROANATOMICAL

584 TAKASHI

BASIS OF MANIPULATION

EVIDENCE FROM FUNCTIONAL TSUKIURA’.‘,

MASAHIKO

TOSHIMITSU

RUITING

XIAO2,3, JIRO OKUDA’, TOSHIKATSU

Tsukuba 305-8568; and CREST,

Aoba-ku, Sendai 980-8575, Japan; JST

The aim of the present study is to investigate neural correlates of processes verbal information, EPI sequence).

FLJJII’,

YAMADORI’

Tohoku Univ. Sch. of Med. 2-l Seiryo-machi,

ZElectrotechnical Lab., l-l-4 Umezono,

VERBAL INFORMATION;

MRI

TAKAHASHF.7,

INASE?.“, TOSHIO IIJIMA*,3, ATSUSHI

‘Dept. of Neuropsychology,

OF SHORT-TERM

concerned with manipulation of short-term

using functional magnetic resonance imaging (fMRI; GE signa 3T system with T2* weighted gradient echo

We prepared two tasks; digit span and lag 1 digit span. Stimuli were presented through visual modality. In

the digit span task, subjects were required to maintain four digits in mind for a short period. In the lag 1 digit span task. they were asked not only to maintain four digits but also to subtract one from each digit in a short period. Subtraction of the first condition from the second one was performed

for each subject on a voxel by voxel basis, and then t-map was constructed

using

statistical parametric mapping (SPM). From this analysis, we found that task-related brain areas were the left posterior superior temporal gyrus, inferior frontal gyrus, right supramarginal

gyrus, middle frontal gyrus, and the posterior region of the cingulate

gyrus. These results suggest that concurrent activation of the frontal lobe and posterior association cortices is necessary for manipulating

585

short-term verbal information.

ANFMRI

STUDY OF THE DORSOLATERAL PREFRONTAL SPATIAL VERBAL WORKING MEMORY TASKS.

TOSHIMITSU TAKAHAS HI”, RUITING XIAO”, KENJI KAWANO”, TOSHIO IrJIMALz.

MASAHIKO

INASE”,

CORTEX ACTIVATION

TAKASHI

TSUKIURA”,

DURING NON-

KENJI K&SAKULJ,

‘Electrotechnical Lab, Tsukuba 305-8568; CREST, JST, Kawaguchi 332-0012; 3Dept. of Neuropsychology, Tohoku Univ. Sch. of Med., Sendai 980~8575;‘Dept. of Neurological Surgery, Chtta Univ. Sch. of Med., 1-8-1 Inohana, Chuoh-ku, Chiia 260-8670, Japan. According to the two-level hypothesis about the prefrontal functions in working memory (WM), dorsolateral prefrontal cortex (DLPFC) is recruited when active manipulation and monitoring of information within WM is required (Petrides, M., 1996). WC examined whether larger demands of monitoring processes would induce more activation in this area. Subjects performed two kinds of non-spatial verbal WM tasks which requires different degree of monitoring processes. In task 1, a set of alphabets were presented to the subjects one after another. One of the letters was marked in every presentation and the subjects were required to remember the marked letters in the presented order. In task 2, a set of alphabets were similarly presented, but no letter was marked. The subjects were required to select a different letter in each presentation and to remember the letters in the selected order. The comparable region in the DLPFC was activated in both tasks and activation in the region during task 2 was greater than that during task]. These results suggest that larger demands of monitoring processes would induce more activation in the same region in the prefrontal cortex.