Evoked gamma band synchronization and the liability for schizophrenia*1

Hong, L. Elliot; Summerfelt, Ann; McMahon, Robert P.; Adami, Helene; Francis, G.; Elliott, Amie; Boyer, Robert; Thaker, Gunvant K.

doi:10.1016/j.schres.2003.12.011

Cited by 189 publications

(177 citation statements)

References 36 publications

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“…Previous studies using a similar click train paradigms (Hong et al 2004;Kwon et al 1999;Light et al 2006) do not confirm an increase in 20-Hz response to 40-Hz drive in the schizophrenic subjects, although Kwon et al does seem to show presence of such a signal but without statistical significance. Our modeling points to several reasons that this may be the case.…”

Section: Modeling Suggests Reasons That Schizophrenic Enhanced 20-hz mentioning

confidence: 78%

Modeling Gaba Alterations in Schizophrenia: A Link Between Impaired Inhibition and Altered Gamma and Beta Range Auditory Entrainment

Vierling-Claassen¹,

Siekmeier²,

Stufflebeam³

2008

Schizophrenia Research

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Vierling-Claassen D, Siekmeier P, Stufflebeam S, Kopell N. Modeling GABA alterations in schizophrenia: a link between impaired inhibition and altered gamma and beta range auditory entrainment. J Neurophysiol 99: 2656 -2671, 2008. First published February 20, 2008 doi:10.1152/jn.00870.2007. The disorganized symptoms of schizophrenia, including severely disordered thought patterns, may be indicative of a problem with the construction and maintenance of cell assemblies during sensory processing and attention. The gamma and beta frequency bands (15-70 Hz) are believed relevant to such processing. This paper addresses the results of an experimental examination of the cortical response of 12 schizophrenia patients and 12 control subjects when presented with auditory click-train stimuli in the gamma/beta frequency band during measurement using magnetoencephalography (MEG), as well as earlier work by Kwon et al. These data indicate that control subjects show an increased 40-Hz response to both 20-and 40-Hz stimulation as compared with patients, whereas schizophrenic subjects show a preference for 20-Hz response to the same driving frequencies. In this work, two computational models of the auditory cortex are constructed based on postmortem studies that indicate cortical interneurons in schizophrenic subjects have decreased GAT-1 (a GABA transporter) and GAD 67 (1 of 2 enzymes responsible for GABA synthesis). The models transition from control to schizophrenic frequency response when an extended inhibitory decay time is introduced; this change captures a possible effect of these GABA alterations. Modeling gamma/beta range auditory entrainment in schizophrenia provides insight into how biophysical mechanisms can impact cognitive function. In addition, the study of dynamics that underlie auditory entrainment in schizophrenia may contribute to the understanding of how gamma and beta rhythms impact cognition in general.

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Section: Modeling Suggests Reasons That Schizophrenic Enhanced 20-hz mentioning

confidence: 78%

Modeling Gaba Alterations in Schizophrenia: A Link Between Impaired Inhibition and Altered Gamma and Beta Range Auditory Entrainment

Vierling-Claassen¹,

Siekmeier²,

Stufflebeam³

2008

Schizophrenia Research

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“…In examining the outlier's demographic and clinical data we could not find any particular measures that distinguished this patient from the rest of the SZ group. Individual patients with extremely large 20 Hz ASSRs have not been reported in the three other published ASSR studies of schizophrenia patients (7,8,10). Further research will be necessary to determine whether these patients may in fact represent a particular subtype of schizophrenia.…”

Section: Discussionmentioning

confidence: 94%

γ-Band Auditory Steady-State Responses Are Impaired in First Episode Psychosis

Spencer¹,

Salisbury²,

Shenton³

et al. 2008

Biological Psychiatry

302

263

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“…The role of specific medications in influencing MEG based metrics of this type is unknown, although current thinking supports the concept that antipsychotic medications may serve to normalize otherwise disturbed function. Of note is the publication by Hong et al (2004) which reported significantly higher 40 Hz EEG power in their atypically medicated schizophrenic subjects compared to those taking conventional antipsychotics. If these findings can be extrapolated to MEG it would suggest that, if anything, the effects of atypical antipsychotic medication would be to reduce differences we observed between the groups.…”

Section: Discussionmentioning

confidence: 99%

“…A similar experiment (Gallinat et al, 2004) using an auditory oddball stimulus failed to produce this result in the early (defined to be 20 -100 ms poststimulus) but did find a reduction in response amplitude in the late (defined as 220 -350ms) window, and in this case the finding was specific to the right frontal region and all of the patients were un-medicated. Hong et al (2004) demonstrated a similar reduction in evoked potential amplitude to click trains (476 ms length) in un-medicated first degree relatives of schizophrenic patients, but failed to replicate the reduction in the medicated patients themselves. Most recently, Light et al (2006) report a reduction in 40 Hz evoked power and inter-trial phase coherence at electrode site Fz in patients with schizophrenia using a 500 ms click train stimulus similar to that of Kwon and colleagues.…”

Section: Introductionmentioning

confidence: 94%

Cortical source estimates of gamma band amplitude and phase are different in schizophrenia

et al. 2008

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Reductions in gamma band phase synchrony and evoked power have been reported in schizophrenic subjects in response to auditory stimuli. These results have been observed in the EEG at one or two electrode sites. We wished to extend these results using magnetic field data to estimate the responses at the neural generators themselves in each hemisphere. Whole head magnetoencephalographic (MEG) recordings were used to estimate the phase and amplitude behavior of sources in primary auditory cortex in both hemispheres of schizophrenic and comparison subjects. Both ipsi-and contralateral cases were evaluated using a driving (40 Hz modulated 1 kHz carrier) and a non-driving (1 kHz tone) stimulus. We used source space projection (SSP) to collapse the magnetic field data into estimates of the time course of source strengths in individual trials. Complex wavelet based timefrequency decomposition was used to compute inter-trial phase locking factor (PLF), and mean evoked and induced amplitude for each cortical generator. Schizophrenic subjects showed reduced SSP PLF and evoked source strength for contra-lateral generators responding to the driving stimulus in both hemispheres. For the pure tone stimulus, only the left hemisphere PLF's in the transient window were reduced. In contrast, subjects with schizophrenia exhibited higher induced 40 Hz power to both stimulus types, consistent with the reduced PLF findings. The method of SSP combined with wavelet based complex demodulation produces a significant improvement in signal-to-noise ratio, and directly estimates the activity of the cortical generators responsible for gamma band auditory MEG evoked fields. Schizophrenic subjects exhibit significant impairment of generation and phase locking of this activity in auditory cortex, suggesting an impairment of GABA-ergic inhibitory interneuronal modulation of pyramidal cell activity.

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Evoked gamma band synchronization and the liability for schizophrenia*1

Cited by 189 publications

References 36 publications

Modeling Gaba Alterations in Schizophrenia: A Link Between Impaired Inhibition and Altered Gamma and Beta Range Auditory Entrainment

Modeling Gaba Alterations in Schizophrenia: A Link Between Impaired Inhibition and Altered Gamma and Beta Range Auditory Entrainment

γ-Band Auditory Steady-State Responses Are Impaired in First Episode Psychosis

Cortical source estimates of gamma band amplitude and phase are different in schizophrenia

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