ワーキングメモリ・実行機能 Working Memory and Executive Function
O1-9-2-1 言語性のボトムアップ的注意を支える左側頭頂皮質：経頭蓋直流電流刺激法による検討 The left posterior parietal cortex subserves verbal bottom-up attention: A tDCS study ○源健宏1, 東美由紀2, 矢追健2, 苧阪満里子1, 美馬達哉3, 福山秀直3, 苧阪直行2 ○Takehiro Minamoto1, Miyuki Azuma2, Ken Yaoi2, Mariko Osaka1, Tatsuya Mima3, Hidenao Fukuyama3, Naoyuki Osaka2 大阪大院・人科1, 京大大院・文・心理2, 京大大院・医3 Grad Sch of Human Sciences, Osaka Univ, Osaka1, Grad Sch of Letters, Kyoto Univ, Kyoto2, Grad Sch of Medicine, Kyoto Univ, Kyoto3 The posterior parietal cortex (PPC) has been shown to be involved in attentional processing. Using a reading span test (RST), we showed activation of the left PPC when participants focused on a target word embedded in a sentence to be read. In the present study, using the transcranial direct current stimulation (tDCS), we investigated a causal role of the left PPC in attentional processing. Participants performed two kinds of RST: focused RST and non-focused RST. In the focused RST, a target word corresponds to the word with core meaning in a sentence (focused word). In the non-focused RST, a word other than the focused word is designated to the target word. In both tasks, participants were required to read four sentences while memorizing target words for a subsequent recall. Participants were divided into two groups, and one group received anodal tDCS and sham, while the other group received cathodal tDCS and sham. As the result, a significant interaction was obtained in the anodal tDCS group, where recall performance was better in the focused RST condition than the non-focused RST in response to the tDCS but not to sham. Such interaction was not observed in the cathodal tDCS group. The result in the anodal tDCS condition can be explained by the bottom-up attentional processing, where attention captures salient information in a context. Specifically, enhancement of the attentional processing by the anodal tDCS on the left PPC helped participants detect the target words in the focused RST, while it distracted their attention from non-focused target to focused distractor in the non-focused RST. The lack of inhibitory cathodal effect is repeatedly reported in the cognitive domain, accounting for the non-significant effect of the cathodal tDCS in the present study.	O1-9-2-2 サル前頭前野における手がかり―標的連合課題時の手がかり刺激のコーディング Coding of cue stimuli in the monkey prefrontal cortex in a cue-target association task ○楠真琴1,2, 門久美紀子1,2 ○Makoto Kusunoki1,2, Mikiko Kadohisa1,2, Mark Stokes1,3, John Duncan1,2 Dept Exp Psych, Univ of Oxford, Oxford, United Kingdom1, Cognition and Brain Sci Unit, MRC, Cambridge, United Kingdom2, Oxford Centre for Human Brain Activity, Univ. of Oxford, United Kingdom3 Prefrontal cortex has long been associated with flexible cognitive function which is fundamental to adaptive behaviour. However the neural mechanism that enable prefrontal cells to adapt their response properties according to context-dependent rules remain poorly understood. To study the neural mechanism underlying context-dependent flexible behaviour, we recorded single unit activities in the dorsolateral prefrontal cortex (DLPFC) of the monkey in a cued-target detection task. On each trial, a cue indicated the target picture to be sought in a forthcoming choice display. When the target was present in the choice display, the monkey was rewarded for a delayed saccade to its location. When a nontarget was present, the monkey was required to maintain fixation. Nontargets could be target pictures associated with a different cue, or pictures never serving as targets on any trial. As this task requires the monkeys to choose proper behaviour to a choice stimulus depending on the cue, we analyzed single unit activities, as well as local field potentials during and after the cue presentation to test if there is a change of functional connectivity in the DLPFC. A group of cells showed phasic cue type selective responses to the cue presentation with short latency, while another showed tonic selectivity developing in 200-300 ms after the cue onset and lasting until the delay period after the cue offset. Population analysis of single unit activities also showed that an instruction cue triggers a rapid series of state-transitions before settling into a stable state which continues to the delay period. To test whether the change of functional connectivity is involved in the network status change, we also analyzed the spike triggered LFP and cross correlation of spike activities in different cue conditions. The results suggest that some of local connectivity changes as the task condition changes.
O1-9-2-3 二重課題におけるサル前頭連合野神経活動 Prefrontal neuronal activity during simultaneous performance of a spatial attention and a spatial working memory tasks ○渡邉慶1,2, 船橋新太郎3 ○Kei Watanabe1,2, Shintaro Funahashi3 Dept. of Experimental Psychology, Oxford University1, 日本学術振興会2, 京都大学こころの未来研究センター3 Dept. of Experimental Psychology, Oxford University, UK1, Japan Society for the Promotion of Science (JSPS), Tokyo, Japan2, Kokoro Res. Centr., Kyoto Univ., Kyoto, Japan3 The need to perform two tasks at once is common in everyday life. However, the difficulty in maintaining perfect performance in both tasks is apparent from our daily experience and societal concerns (e.g., driving and cell phone talking). In many dual-tasks, behavioral signs of capacity overflow, such as decrease in percent correct rates and prolonged response times relative to single-tasks, become evident. This effect, dual-task interference, is thought to be a direct evidence of cognitive capacity limitation, and the involvement of the lateral prefrontal cortex (LPFC) has long been implicated. However, due to the lack of neurophysiological studies, the underlying mechanisms remain largely unknown. Here, using two monkeys trained to perform a dual-task requiring simultaneous performance of a spatial attention task and a spatial memory task, we show that the signatures of dual-task interference were manifest not only at behavioral performance of the monkeys but also at activities of single LPFC neurons. In dual-tasks, the monkeys exhibited a classic pattern of dual-task interference; the component task performances were deteriorated to a degree proportional to the difficulty level of the concurrent counterpart task. Correspondingly, LPFC neuron activities exhibited remarkable attenuation of selectivity for task content (i.e., spatial location) even in correct trials, to a degree proportional to the increased demand of the concurrent task. These results indicate that information processing capacity of LPFC neuron is (1) limited to a fixed level, below that fully accommodates information of two concurrent tasks, (2) adaptively allocated between tasks in graded quantity, suggesting that this functional limitation of LPFC neuron activity underlies behavioral dual-task interference. The present findings suggest that the neural mechanisms of capacity limitation can be elucidated at single-neuron level using nonhuman primate models of dual-task interference effect.	O1-9-2-4 fMRI based-estimation of memory recovery for NPC patients treated by ionizing radiation therapy ○Sharon Chen1, Yoshifumi Abe2, Yi-ting Wan3, Tatsuhiro Hisatsune2, Gin-Chung Liu4, Yu-Ting Kuo4, Chih-Jen Huang5, Shi-Long Lian5 Kaohsiung Medical University, Kaohsiung, Taiwan1, Department of Integrated Biosciences, The University of Tokyo, Japan2, Department of Occupational Therapy, Kaohsiung Medical University, Taiwan3, Department of Medical Imaging, Kaohsiung Medical University Chung-Ho Memorial Hospital, Taiwan4, Department of Radiotherapy, Kaohsiung Medical University Chung-Ho Memorial Hospital, Taiwan5 NasoPharyngeal Carcinoma (NPC), functional Magnetic Radiation therapy is the most common treatment for NasoPharyngeal Carcinoma (NPC). If hippocampus got overdose during the treatment, the memory would be damaged. In this study, a functional estimation will be applied to explore the recovery in the cognitive function including memory after radiotherapy. NPC patients are recruited to undergo a routine radiotherapy, whose protocol sets target dosage 70Gy in 35 fractions within 7 weeks. In this condition, hippocampal area accepts about 20Gy dosage. Patients have to receive three time assessments of functional Magnetic Resonance Imaging (fMRI) scan, including before radiation treatment, one month after treatment and three months after treatment. fMRI scans include twoparts: (1) N-back working memory task and (2) resting state functional connectivity (FC) analysis. The fMRI are acquired based on the BOLD-EPI protocol: 22x22 cm2 field-of-view (FOV), 64x64 matrix (3.4x3.4 mm2 in-plane resolution), 35 ms echo time (TE), 80o flip angle (FA), 4mm slice thickness and 2000 ms repetition time (TR). Data analysis is utilized Statistical Parametric Mapping (SPM) method. For FC analysis, we set seed-ROI at the both side of the hippocampus before the statistical inference. fMRI result from two NPC patients (2 males, average age is 52 years old) shows that patients got degraded memory after radiation exposure but it got recovered after 3 months at the areas of hippocampus, dosolateral prefrontal cortex and premotor cortex especially in the two-back test. Furthermore, the resting-state fMRI result presented that the functional connectivity of the hippocampus to the related cortical areas recovered after 3 months. From current finding, memory recovery is possible and the deficit caused by radiation exposure is impermanent. However, the extent of recovering back to the original state before treatment is still worthy of further study.

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