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Dive into the research topics where Tomoki Haji is active.

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Featured researches published by Tomoki Haji.


Investigative Ophthalmology & Visual Science | 2014

White matter consequences of retinal receptor and ganglion cell damage.

Shumpei Ogawa; Hiromasa Takemura; Hiroshi Horiguchi; Masahiko Terao; Tomoki Haji; Franco Pestilli; Jason D. Yeatman; Hiroshi Tsuneoka; Brian A. Wandell; Yoichiro Masuda

PURPOSE Patients with Leber hereditary optic neuropathy (LHON) and cone-rod dystrophy (CRD) have central vision loss; but CRD damages the retinal photoreceptor layer, and LHON damages the retinal ganglion cell (RGC) layer. Using diffusion MRI, we measured how these two types of retinal damage affect the optic tract (ganglion cell axons) and optic radiation (geniculo-striate axons). METHODS Adult onset CRD (n = 5), LHON (n = 6), and healthy controls (n = 14) participated in the study. We used probabilistic fiber tractography to identify the optic tract and the optic radiation. We compared axial and radial diffusivity at many positions along the optic tract and the optic radiation. RESULTS In both types of patients, diffusion measures within the optic tract and the optic radiation differ from controls. The optic tract change is principally a decrease in axial diffusivity; the optic radiation change is principally an increase in radial diffusivity. CONCLUSIONS Both photoreceptor layer (CRD) and retinal ganglion cell (LHON) retinal disease causes substantial change in the visual white matter. These changes can be measured using diffusion MRI. The diffusion changes measured in the optic tract and the optic radiation differ, suggesting that they are caused by different biological mechanisms.


Cerebral Cortex | 2014

Inter- and Intrahemispheric Connectivity Differences When Reading Japanese Kanji and Hiragana

Keith J. Kawabata Duncan; Tae Twomey; Ōiwi Parker Jones; Mohamed L. Seghier; Tomoki Haji; Katsuyuki Sakai; Cathy J. Price; Joseph T. Devlin

Unlike most languages that are written using a single script, Japanese uses multiple scripts including morphographic Kanji and syllabographic Hiragana and Katakana. Here, we used functional magnetic resonance imaging with dynamic causal modeling to investigate competing theories regarding the neural processing of Kanji and Hiragana during a visual lexical decision task. First, a bilateral model investigated interhemispheric connectivity between ventral occipito–temporal (vOT) cortex and Brocas area (“pars opercularis”). We found that Kanji significantly increased the connection strength from right-to-left vOT. This is interpreted in terms of increased right vOT activity for visually complex Kanji being integrated into the left (i.e. language dominant) hemisphere. Secondly, we used a unilateral left hemisphere model to test whether Kanji and Hiragana rely preferentially on ventral and dorsal paths, respectively, that is, they have different intrahemispheric functional connectivity profiles. Consistent with this hypothesis, we found that Kanji increased connectivity within the ventral path (V1 ↔ vOT ↔ Brocas area), and that Hiragana increased connectivity within the dorsal path (V1 ↔ supramarginal gyrus ↔ Brocas area). Overall, the results illustrate how the differential processing demands of Kanji and Hiragana influence both inter- and intrahemispheric interactions.


Journal of Neurophysiology | 2012

Human neural responses involved in spatial pooling of locally ambiguous motion signals

Kaoru Amano; Tsunehiro Takeda; Tomoki Haji; Masahiko Terao; Kazushi Maruya; Kenji Matsumoto; Ikuya Murakami; Shin'ya Nishida

Early visual motion signals are local and one-dimensional (1-D). For specification of global two-dimensional (2-D) motion vectors, the visual system should appropriately integrate these signals across orientation and space. Previous neurophysiological studies have suggested that this integration process consists of two computational steps (estimation of local 2-D motion vectors, followed by their spatial pooling), both being identified in the area MT. Psychophysical findings, however, suggest that under certain stimulus conditions, the human visual system can also compute mathematically correct global motion vectors from direct pooling of spatially distributed 1-D motion signals. To study the neural mechanisms responsible for this novel 1-D motion pooling, we conducted human magnetoencephalography (MEG) and functional MRI experiments using a global motion stimulus comprising multiple moving Gabors (global-Gabor motion). In the first experiment, we measured MEG and blood oxygen level-dependent responses while changing motion coherence of global-Gabor motion. In the second experiment, we investigated cortical responses correlated with direction-selective adaptation to the global 2-D motion, not to local 1-D motions. We found that human MT complex (hMT+) responses show both coherence dependency and direction selectivity to global motion based on 1-D pooling. The results provide the first evidence that hMT+ is the locus of 1-D motion pooling, as well as that of conventional 2-D motion pooling.


Neuroreport | 2016

Regional gray matter volume in the posterior precuneus is associated with general self-efficacy.

Ayaka Sugiura; Ryuta Aoki; Kou Murayama; Yoshihiko Yomogida; Tomoki Haji; Atsuko Saito; Toshikazu Hasegawa; Kenji Matsumoto

Motivation in doing a task is influenced not only by the expected outcome of the task but also by the belief that one has in successfully executing the task. Over time, individuals accumulate experiences that contribute toward a general belief in one’s overall ability to successfully perform tasks, which is called general self-efficacy (GSE). We investigated the relationship between regional gray matter volume and individual differences in GSE. Brain anatomy was analyzed using magnetic resonance images obtained from 64 healthy right-handed participants who had completed Sherer’s GSE scale. After controlling for other factors related to motivation, age, sex, and total gray matter volume of each participant, results showed that regional gray matter volume in the posterior part of the precuneus significantly and positively correlated with the GSE score. These results suggest that one’s accumulated experiences of success and failure, which contribute toward GSE, also influence the anatomical characteristics of the precuneus.


NeuroImage | 2014

Prefrontal mechanisms in preference and non-preference-based judgments

Jerome Clifford Foo; Tomoki Haji; Katsuyuki Sakai

When we decide between two options, we can make our decision based on what we prefer, (preference-based choice), or we can also choose based on which option we want to avoid more (non-preference-based choice). Most decision making research has examined preference-based choice but has not differentiated it from non-preference-based choice. The decision making process can be decomposed into multiple value-based computational processes, which are shown to be subserved by different regions in the prefrontal cortex (PFC). Here we show that the same decision circuits within the PFC are configured differently depending on whether decisions are made based on preference or non-preference criteria (decision rule). Activation in the dorsolateral PFC changed depending on both the values of the two choice options and decision rule. We also found that activation in the medial and lateral PFC was modulated linearly according to the difference in value between the two items and according to the value of the chosen item, respectively. In the medial and lateral PFC, there were distinct patterns of activation between dorsal and ventral regions: in dorsal regions value-related changes in activation were modulated by the decision rule, whereas in ventral regions activation patterns were not modulated. We propose that preference and non-preference decision rules represented in the dorsal PFC differently configure decision processes, resulting in context-specific significance being attached to the choice values represented in the ventral PFC.


Cortex | 2014

Different impressions of other agents obtained through social interaction uniquely modulate dorsal and ventral pathway activities in the social human brain

Hideyuki Takahashi; Kazunori Terada; Tomoyo Morita; Shinsuke Suzuki; Tomoki Haji; Hideki Kozima; Masahiro Yoshikawa; Yoshio Matsumoto; Takashi Omori; Minoru Asada; Eiichi Naito


Archive | 2015

Electroencephalographic and Magnetoencephalographic Recordings Spatiotemporal Dynamics of Feature-Based Attention Spread: Evidence from Combined

H. J. Aronen; R. J. Ilmoniemi; G. V. Simpson; Anders M. Dale; J. W. Belliveau; A. Korvenoja; Therese Lennert; Roberto Cipriani; Pierre Jolicoeur; Douglas Cheyne; C Julio; Ikuya Murakami; Tsunehiro Takeda; Tomoki Haji; Masahiko Terao; Kazushi Maruya; Hans-Jochen Heinze; Jens-Max Hopf; Mircea Ariel; Michael Stoppel; Hendrik Strumpf; Ruth M. Krebs


Archive | 2015

MotionManual Following Responses to Visual Tunings of Human Cortical Responses and Close Similarity Between Spatiotemporal Frequency

Kaoru Amano; Toshitaka Kimura; Tsunehiro Takeda; Ikuya Murakami; Tomoki Haji; Masahiko Terao; Kazushi Maruya; Hiromasa Takemura; Hiroshi Ashida; Akiyoshi Kitaoka


Investigative Ophthalmology & Visual Science | 2014

Disease in the photoreceptors (JMD) or retinal ganglion cells (LHON) affects optic tract and radiation tissue properties

Shumpei Ogawa; Hiromasa Takemura; Hiroshi Horiguchi; Masahiko Terao; Tomoki Haji; Franco Pestilli; Jason D. Yeatman; Hiroshi Tsuneoka; Brian A. Wandell; Yoichiro Masuda


Investigative Ophthalmology & Visual Science | 2013

Population receptive field estimates in V1 lesion projection zone of patients with macular degeneration onset at different ages

Yoichiro Masuda; Masahiko Terao; Tomoki Haji; Kaoru Amano; Hiroshi Horiguchi; Shumpei Ogawa; Ikuya Murakami; Kenji Matsumoto; Hiroshi Tsuneoka; Brian A. Wandell

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Hiromasa Takemura

National Institute of Information and Communications Technology

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Hiroshi Horiguchi

Jikei University School of Medicine

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Hiroshi Tsuneoka

Jikei University School of Medicine

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Yoichiro Masuda

Jikei University School of Medicine

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