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  • 1
    Online Resource
    Online Resource
    Functional Magnetic Resonance Imaging of Eye Dominance at 4 Tesla
    S. Karger AG ; 2001
    In:  Ophthalmic Research Vol. 33, No. 5 ( 2001), p. 276-282
    Details
    In: Ophthalmic Research, S. Karger AG, Vol. 33, No. 5 ( 2001), p. 276-282
    Abstract: We studied eye dominance in visual cortex and lateral geniculate nucleus (LGN) using functional magnetic resonance imaging (fMRI) at a very high magnetic field (4 tesla). Eight normal volunteers were studied with fMRI at 4 tesla during alternating monocular visual stimulation. The acquisition was repeated twice in 4 subjects to confirm reproducibility. In addition, magnetic resonance signal intensities during three conditions (right eye stimulation, left eye stimulation, and control condition) were compared to determine whether the observed area was truly or relatively monocular in 2 subjects. In both the individual and group analyses, the anterior striate cortex was consistently activated by the contralateral eye more than the ipsilateral eye. Additionally, we found evidence that there were areas in the bilateral LGN which were more active during the stimulation of the contralateral eye than during the stimulation of the ipsilateral eye. The activated areas were reproducible, and the mean ratio of the overlapping area was 0.71 for the repeated scans. The additional experiment revealed that the area in the anterior visual cortex could be divided into two parts, one truly monocular and the other relatively monocular. Our finding confirmed previous fMRI results at 1.5 tesla showing that eye dominance was observed in the contralateral anterior visual cortex. However, the eye dominance in the visual cortex was found not only in the most anterior area corresponding to the monocular temporal crescent but also in the more posterior area, presumably showing the greater sensitivity of the temporal visual field (nasal retina) as compared with the nasal visual field (temporal retina) in the peripheral visual field (peripheral retina). In addition, it is suggested that the nasotemporal asymmetry of the retina and the visual fields is represented in the LGN as well as in the visual cortex.
    Type of Medium: Online Resource
    ISSN: 0030-3747 , 1423-0259
    URL: Article
    DOI: 10.1159/000055681
    RVK:
    XA 10000
    Language: English
    Publisher: S. Karger AG
    Publication Date: 2001
    detail.hit.zdb_id: 1483177-6
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  • 2
    Online Resource
    Online Resource
    Prodromal Symptom Severity Predicts Accelerated Gray Matter Reduction and Third Ventricle Expansion among Clinically High-Risk Youth Developing Psychotic Disorders
    S. Karger AG ; 2015
    In:  Complex Psychiatry Vol. 1, No. 1 ( 2015), p. 13-22
    Details
    In: Complex Psychiatry, S. Karger AG, Vol. 1, No. 1 ( 2015), p. 13-22
    Abstract: A recent prospective longitudinal neuroimaging study of 274 prodromal risk syndrome subjects revealed that those who later developed full-blown psychotic symptoms had exhibited accelerated gray matter loss and third ventricle expansion around the time of psychosis onset. Previous studies also indicate that higher levels of unusual thought content during prodromal states are a significant predictor of psychosis in clinically high-risk (CHR) youth. However, the relationship between clinical symptoms and changes in neuroanatomical structure has not been previously examined in the North American Prodrome Longitudinal Study (NAPLS) sample at the whole-brain level. In this report, we investigated whether symptom severity as measured by the Scale of Prodromal Symptoms (SOPS) predicted the accelerated gray matter decline in 274 CHR cases, including 35 who converted to psychosis. Higher levels of unusual thought content at baseline were associated with a steeper rate of gray matter loss in the prefrontal cortex bilaterally among converters. In contrast, there was no association found among nonconverters. Steeper gray matter loss seems to be unique to those (CHR) individuals with higher levels of subpsychotic predelusional symptoms that acutely worsen in the ramp-up to full-blown psychosis, and as such may reflect pathophysiological processes driving the emergence of psychosis.
    Type of Medium: Online Resource
    ISSN: 2673-3005 , 2673-298X
    URL: Article
    DOI: 10.1159/000371887
    Language: English
    Publisher: S. Karger AG
    Publication Date: 2015
    detail.hit.zdb_id: 3021167-0
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  • 3
    Online Resource
    Online Resource
    Neural Correlates of Schizophrenia Negative Symptoms: Distinct Subtypes Impact Dissociable Brain Circuits
    S. Karger AG ; 2015
    In:  Complex Psychiatry Vol. 1, No. 4 ( 2015), p. 191-200
    Details
    In: Complex Psychiatry, S. Karger AG, Vol. 1, No. 4 ( 2015), p. 191-200
    Abstract: 〈 b 〉 〈 i 〉 Background: 〈 /i 〉 〈 /b 〉 The negative symptoms of schizophrenia include deficits in emotional expression and motivation. These deficits are stable over the course of illness and respond poorly to current medications. Previous studies have focused on negative symptoms as a single category; however, individual symptoms might be related to separate neurological disturbances. We analyzed data from the Functional Biomedical Informatics Research Network dataset to explore the relationship between individual negative symptoms and functional brain activity during an auditory oddball task. 〈 b 〉 〈 i 〉 Methods: 〈 /i 〉 〈 /b 〉 Functional magnetic resonance imaging was conducted on 89 schizophrenia patients and 106 healthy controls during a two-tone auditory oddball task. Blood oxygenation level-dependent (BOLD) signal during the target tone was correlated with severity of five negative symptom domains from the Scale for the Assessment of Negative Symptoms. 〈 b 〉 〈 i 〉 Results: 〈 /i 〉 〈 /b 〉 The severity of alogia, avolition/apathy and anhedonia/asociality was negatively correlated with BOLD activity in distinct sets of brain regions associated with processing of the target tone, including basal ganglia, thalamus, insular cortex, prefrontal cortex, posterior cingulate and parietal cortex. 〈 b 〉 〈 i 〉 Conclusions: 〈 /i 〉 〈 /b 〉 Individual symptoms were related to different patterns of functional activation during the oddball task, suggesting that individual symptoms might arise from distinct neural mechanisms. This work has potential to inform interventions that target these symptom-related neural disruptions.
    Type of Medium: Online Resource
    ISSN: 2673-3005 , 2673-298X
    URL: Article
    DOI: 10.1159/000440979
    Language: English
    Publisher: S. Karger AG
    Publication Date: 2015
    detail.hit.zdb_id: 3021167-0
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