Publications by authors named "Yoshimi Ohgami"

The present study examined the effects of unilateral stimulus presentation on the right hemisphere preponderance of the stimulus-preceding negativity (SPN) in the event-related potential (ERP) experiment, and aimed to elucidate whether unilateral stimulus presentation affected activations in the bilateral anterior insula in the functional magnetic resonance imaging (fMRI) experiment. Separate fMRI and ERP experiments were conducted using visual and auditory stimuli by manipulating the position of stimulus presentation (left side or right side) with the time estimation task. The ERP experiment revealed a significant right hemisphere preponderance during left stimulation and no laterality during the right stimulation.

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Recent functional studies have reported that amygdala and anterior cingulate cortex (ACC) dysfunction is a reproducible and good biomarker of major depressive disorder. When we use the activation of these regions as biomarkers of major depressive disorder, a short and simple stimulation paradigm could be preferable to reduce the burden on patients. However, negativity bias, which is the phenomenon by which negative stimuli are processed noticeably faster than positive stimuli, might affect the activation of these regions in the short and simple stimulation paradigm.

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The present study investigated whether auditory stimuli with different contents affect right laterality and the components of stimulus-preceding negativity (SPN). A time-estimation task was performed under voice, rhythm, beep, and control conditions. The SPN interval during which participants anticipated the stimulus was divided into quarters to define early and late SPNs.

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The stimulus-preceding negativity (SPN) is an event-related potential (ERP) reflecting anticipation. The anterior insular cortex is assumed to be one of the physiological sources of the SPN. However, the precise neural substrates of the SPN have yet to be confirmed.

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The present study investigated whether the right hemisphere preponderance of stimulus-preceding negativity (SPN) was affected by different categories of visual feedback stimulus. A time estimation task was performed with facial, verbal, symbolic, and no-feedback conditions. A principal component analysis identified an early component of SPN in addition to a late component that was morphologically similar to the original SPN.

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Neurobiological accounts of the dopaminergic reward system and psychophysiological explanations of the error-related negativity (ERN) both emphasize the comparison of expected versus actual outcome for voluntary actions. The stimulus-preceding negativity (SPN) constitutes a valuable index of that expectation, in that it has high temporal resolution and its anatomical, cognitive and affective correlates have been reasonably well characterized. This review links established findings regarding the SPN to current research on the dorsal and ventral attention systems, somatic marker hypothesis, ERN, the reward system and relevant neurological and psychiatric findings.

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The stimulus-preceding negativity (SPN) is an event-related potential that reflects emotional and perceptual anticipation. The SPN is characterized by a right hemisphere preponderance in amplitude, and previous studies suggest that activity in the insular cortex might contribute to the amplitude of the SPN. Although the insula might contribute to the SPN's occurrence, the exact role of the insula in the pattern of SPN right hemisphere dominance remains unclear.

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This study examined the effects of emotional valence on stimulus-preceding negativity (SPN) using reward and fine. A time estimation task under reward, punishment, combined, and control conditions was performed. Participants were rewarded for accurate responses in the reward condition, and were fined for incorrect estimations in the punishment condition.

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We used functional magnetic resonance imaging to investigate brain activity related to motivational function of informative feedback stimuli in a time estimation task. In that task, subjects pressed a button as a response 3 s after a cue stimulus; a visual feedback stimulus was presented 2 s after the response. In a true feedback condition, subjects received true information (informative feedback) about their time-estimation performance.

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We report a case of breast cancer with spinal and vertebral lesions. A 49-year-old premenopausal woman with a left breast tumor was admitted to our hospital for acute weakness of the lower limbs and dysuria. She could neither stand nor walk.

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Twenty-one subjects underwent event-related fMRI while carrying out a simple visuomotor task in which they responded to stimuli flashed either onto the right visual field, onto the left visual field, or onto both visual fields at once. The aim of this study was to clarify areas of brain activity associated with crossed-uncrossed differences (CUD) and to investigate differences of the brain activity between CUD and redundancy gain. An intriguing brain activation related to CUD was found in the genu of the corpus callosum (CC).

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The present study aimed to investigate the effect of reward and stimulus modality of feedback stimuli on the stimulus-preceding negativity. A time estimation task was performed, and (a) the motivational level (reward and no-reward) and (b) the stimulus modality (auditory and visual) of feedback stimuli were manipulated. The results demonstrated that the stimulus-preceding negativity was larger in the reward than in the no-reward condition, especially at the right frontal and the left occipito-temporal areas.

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In writing to dictation, one mode of language processing is based on the knowledge of how to convert speech sounds to the corresponding letters, namely, phoneme-to-grapheme conversion (phonological mode). Little is known about the neural substrates of the phoneme-to-grapheme conversion. Our study aims to clarify the neural substrates of phoneme-to-grapheme conversion in writing to dictation using functional magnetic resonance imaging.

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