Biomedical subjects

Mingxiong Huang

Publications and source records attributed to Mingxiong Huang.

7 recordsLinked to original sources

PubMed2005

M50 sensory gating predicts negative symptoms in schizophrenia.

Impaired auditory sensory gating is considered characteristic of schizophrenia and a marker of the information processing deficit inherent to that disorder. Predominance of negative symptoms also reflects the degree of deficit in schizophrenia and is associated with poorer pre-morbid functioning, lower IQ, and poorer outcomes. However, a consistent relationship between auditory sensory gating and negative symptoms in schizophrenia has yet to be demonstrated. The absence of such a finding is surprising, since both impaired auditory gating and negative symptoms have been linked with impaired fronto-temporal cortical function. The present study measured auditory gating using the P50 event related potential (ERP) in a paired-click paradigm and capitalized on the relative localization advantage of magnetoencephalography (MEG) to assess auditory sensory gating in terms of the event related field (ERF) M50 source dipoles on bilateral superior temporal gyrus (STG). The primary hypothesis was that there would be a positive correlation between lateralized M50 auditory sensory gating measures and negative symptoms in patients with schizophrenia. A standard paired-click paradigm was used during simultaneous EEG and MEG data collection to determine S2/S1 sensory gating ratios in a group of 20 patients for both neuroimaging techniques. Participants were administered the Schedule for the Assessment of Negative Symptoms (SANS), the Positive and Negative Symptom Scale (PANSS), and the Calgary Depression Scale for Schizophrenia. Consistent with previous reports, there was no relationship between ERP P50 sensory gating and negative symptoms. However, right (not left) hemisphere ERF M50 sensory gating ratio was significantly and positively correlated with negative symptoms. This finding is compatible with information processing theories of negative symptoms and with more recent findings of fronto-temporal abnormality in patients with predominantly negative symptoms.

Adolescent↗

PubMed2005

Distinct M50 and M100 auditory gating deficits in schizophrenia.

The time course of the schizophrenia auditory gating deficit may provide clues to mechanisms of impaired cognition. Magnetoencephalography was recorded during a standard paired-click paradigm. Using source strength of the M50 and M100 components for each click, calculated from dipole locations identified as underlying each component for the first click, a ratio of the second divided by the first was used to measure gating. Patients showed a left-hemisphere gating deficit in M50 and a bilateral gating deficit in M100. Hypothesizing that an early deficit may affect later processing, hierarchical regression was used to examine variance shared between the components. A left-hemisphere M100 gating deficit was coupled with the left M50 gating deficit. In contrast, a right-hemisphere M100 gating deficit was unrelated to M50 gating in either hemisphere. Investigations of interhemisphere gating relations may clarify group differences in regional connectivity and their role in gating.

Adult↗

PubMed2004

Neural representation of interval encoding and decision making.

Our perception of time depends on multiple psychological processes that allow us to anticipate events. In this study, we used event-related functional magnetic resonance imaging (fMRI) to differentiate neural systems involved in formulating representations of time from processes associated with making decisions about their duration. A time perception task consisting of two randomly presented standard intervals was used to ensure that intervals were encoded on each trial and to enhance memory requirements. During the encoding phase of a trial, activation was observed in the right caudate nucleus, right inferior parietal cortex and left cerebellum. Activation in these regions correlated with timing sensitivity (coefficient of variation). In contrast, encoding-related activity in the right parahippocampus and hippocampus correlated with the bisection point and right precuneus activation was associated with a measure of memory distortion. Decision processes were studied by examining brain activation during the decision phase of a trial that was associated with the difficulty of interval discriminations. Activation in the right parahippocampus was greater for easier than harder discriminations. In contrast, activation was greater for harder than easier discriminations in systems involved in working memory (left middle-frontal and parietal cortex) and auditory rehearsal (left inferior-frontal and superior-temporal cortex). Activity in the auditory rehearsal network correlated with memory distortion. Our results support the independence of systems that mediate interval encoding and decision processes. The results also suggest that distortions in memory for time may be due to strategic processing in cortical systems involved in either encoding or rehearsal.

Acoustic Stimulation↗

PubMed2003

A non-invasive method for observing hippocampal function.

A non-invasive method for observing the functioning of the hippocampus could be invaluable in understanding the role of hippocampal abnormalities in many brain disorders. Transverse patterning, a hippocampal-dependent memory task, was used in an attempt to study the functioning hippocampus. Subjects performed transverse patterning while whole-head MEG data were collected. The MEG data were analyzed using a spatial-temporal multiple-dipole approach. Controls showed right hippocampal activation. Patients with unilateral hippocampal damage showed activation in undamaged hippocampus. MEG during transverse patterning performance is a promising, non-invasive tool for assessing hippocampal function.

Adult↗

PubMed2003

Investigation of the normal proximal somatomotor system using magnetoencephalography.

OBJECTIVE: The role of the ipsilateral cortex in proximal muscle control in normal human subjects is still under debate. One clinical finding, rapid recovery of proximal muscle relative to distal muscle use following stroke, has led to the suggestion that the ipsilateral as well as the contralateral motor cortex may be involved in normal proximal muscle control. The primary goal of this project was to identify contralateral and ipsilateral motor cortex activation associated with proximal muscle movement in normal subjects using magnetoencephalography (MEG). METHODS: We developed protocols for a self-paced bicep motor task and a deltoid, electrical-stimulation somatosensory task. The MEG data were analyzed using automated multi-dipole spatiotemporal modeling techniques to localize the sources and characterize the associated timing of these sources. RESULTS: Reliable contralateral primary motor and somatosensory sources localized to areas consistent with the homunculus. Ipsilateral M1 activation was only found in 2/12 hemispheres. CONCLUSIONS: Robust contralateral motor cortex activation and sparse ipsilateral motor cortex activation suggest that the ipsilateral motor cortex is not involved in normal proximal muscle control. SIGNIFICANCE: The results suggest that proximal and distal muscle control is similar in normal subjects in the sense that proximal muscle control is primarily governed by the contralateral motor cortex.

Adult↗

PubMed2003

Lateralization of auditory sensory gating and neuropsychological dysfunction in schizophrenia.

OBJECTIVE: Sensory gating assessed via EEG in a paired-click paradigm has often served as a neurophysiological metric of attentional function in schizophrenia. However, the standard EEG measure of sensory gating using the P50 component at electrode Cz does not foster differential assessment of left and right hemisphere contributions. Magnetoencephalography (MEG) is complementary to EEG, and its analogous M50 component may be better suited for localization and analysis of such lateralized cortical generators. The authors hypothesized that 1) auditory gating would be evident in M50 sources in superior temporal gyrus, demonstrating ratios similar to P50; 2) M50 would resemble P50 in distinguishing gating in comparison subjects and patients with schizophrenia, but M50 would show lateralization of the gating deficit; and 3) P50 and M50 sensory gating ratios would predict neuropsychological measures in patients and comparison subjects, with the MEG identification of left and right hemisphere sources allowing for the evaluation of lateralization in brain-behavior relationships. METHOD: Event-related EEG and MEG recordings were simultaneously obtained from 20 patients with schizophrenia and 15 comparison subjects. P50 amplitudes, M50 dipole source strengths, and P50 and M50 gating ratios were compared and assessed with respect to scores on neuropsychological performance measures. RESULTS: M50 dipoles localizing to superior temporal gyrus demonstrated gating similar to that of P50. As expected, patients demonstrated less P50 gating than did comparison subjects. Left (but not right) hemisphere M50 gating 1) correlated with EEG gating, 2) differentiated patients and comparison subjects, and 3) correlated with neuropsychological measures of sustained attention and working memory. CONCLUSIONS: Converging evidence from EEG, MEG, and neuropsychological measures points to left hemisphere dysfunction as strongly related to the well-established sensory gating deficit in schizophrenia.

Acoustic Stimulation↗

PubMed2002

Central versus peripheral visual field stimulation results in timing differences in dorsal stream sources as measured with MEG.

Small, achromatic circular sinusoids were presented in the central and peripheral visual fields to investigate dorsal visual stream activation. It was hypothesized that peripheral stimulation would lead to faster onset latencies, as well as preferentially activate dorsal stream visual areas relative to central field stimulation. Although both central and peripheral stimulation activated similar areas, the onset latencies of neuromagnetic sources in two dorsal stream areas were found to be significantly shorter for peripheral versus central field stimulation. The results suggest that information from central versus peripheral fields arrives in the higher-order visual areas via different routes.

Adult↗