Annals of Rehabilitation Medicine

Neural Network for Visuospatial Attention in Patients with Traumatic Brain Injury.: Kim, Yun Hee , Park, Ji Won , Ko, Myoung Hwan , Lee, Peter K W; J Korean Acad Rehabil Med 2004;28(5):436-443.

Abstract
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Purpose
To investigate the brain areas related with the deficit in visuospatial attention in patients with traumatic brain injury (TBI) using functional MRI (fMRI). Method: Twenty TBI and fifteen normal subjects were enrolled. The endogenous visuospatial attention task was used as an activation paradigm during fMRI. FMRI was performed on a 3T ISOL Forte scanner. Thirty slices were acquired using a single-shot EPI sequences (TR/TE=3000/ 30 ms, Flip angle 70^o, FOV=220 mm, 64⁓64 matrix, slice thickness 4 mm). The accuracy and reaction time to the attention task were measured during fMRI. Imaging data were analyzed using SPM-99 software. Results: The ratio of accurate responses was lower (p＜0.01)and the average reaction time was slower (p＜0.01) in the TBI group than the normal group. The fMRI analysis showed more activation in the bilateral prefrontal cortices (the middle and inferior frontal gyri) and less activation in the cingulate gyrus, medial frontal lobe, bilateral temporo- occipital areas, and cerebellum in the TBI group compared with the normal group.Conclusion: In TBI patients, impaired visuospatial attention might be resulted from the decreased activity of the cingulate, medial frontal, and temporo-occipital regions accompanied with compensatory hyperactivation of the prefrontal cortex. (J Korean Acad Rehab Med 2004; 28: 436-443)

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Central Neural Networks of Verbal Working Memory and Visuospatial Attention: An Interference Approach Using Low-frequency Repetitive Transcranial Magnetic Stimulation.: Ko, Myoung Hwan , Seo, Jeong Hwan , Jang, Sung Ho , Yoo, Woo Kyoug , Kim, Yun Hee; J Korean Acad Rehabil Med 2004;28(4):301-305.

Abstract
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Objective
We evaluated a role of prefrontal and parietal cortex in verbal working memory and visuospatial attention using repetitive transcranial magnetic stimulation (rTMS). Method: In six healthy volunteers, bilateral prefrontal and parietal cortex was stimulated with rTMS (90% of motor threshold, 10 trains of 1 Hz rTMS) during performed cognitive tasks (two-back verbal working memory task and endogenous visuospatial attention task). rTMS was applied to 4 different sites over left prefrontal, right prefrontal, left parietal and right parietal areas at F3, F4, P3 and P4 location on the scalp, according to the 10/20 EEG system. The sham stimulation was applied with the coil placed perpendicular to the scalp. Results: Reaction time (RT) was significantly prolonged by left prefrontal TMS in verbal working memory. In addition, performance deterioration was also observed during rTMS over the right prefrontal and left parietal areas. In visuospatial attention task, RT was significantly prolonged by right parietal TMS.Conclusion: These results show that left prefrontal cortex play a major role in the network of working memory, and right parietal cortex is important area in the visuospatial attention. We suggest that an rTMS could be a useful method for evaluation of neural network in human brain. (J Korean Acad Rehab Med 2004; 28: 301-305)

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Effects of Methylphenidate on Cognitive Impairment Following Brain Injury: A double-blind placebo-controlled study.: Kim, Yun Hee , Na, Seung Yong , Shin, Yong Il , Seo, Jeong Hwan; J Korean Acad Rehabil Med 2000;24(4):611-627.

Abstract
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Objective: To evaluate the effect of methylphenidate on cognitive function especially on working memory and visuospatial attention in the patients with traumatic brain injury (TBI).

Method: Eighteen subjects, 16 males and 2 females, with TBI were enrolled. Their mean age was 34.2 years old. A double-blind placebo-controlled study was designed. The baseline cognitive assessment was performed before the administration of drug. Two days after the baseline study, 20 mg of methylphenidate or placebo was administered. The second cognitive assessment was performed 2 hours after the treatment. The follow-up assessment conducted two days after the second test. Cognitive assessments consisted of 'one-back working memory task' and 'endogenous visuospatial attention task', designed using SuperLab Pro 2.0^Ⱂ software.

Results: In one-back working memory test, there was significant improvement of response accuracy in methylphenidate group in comparison with placebo group (p＜0.01). Significant shortening of reaction time was also seen after the administration of drug in methylphenidate group (p＜0.05). In endogenous visuospatial attention test, significant improvement of response accuracy was noticed after the administration of drug in methylphenidate group (p＜0.05).

Conclusion: These results demonstrated that the administration of methylphenidate was beneficial in improving cognitive function following TBI. The effect was prominent in the accuracy of working memory.