Somatosensory timing deficits in schizophrenia.

Schizophrenia is often accompanied by disturbances in motor behavior thought to result from abnormalities in the brain's timing mechanisms. Virtually all behavior has a motor component, and proper regulation of motor behavior is often dependent upon accurate registration of somatosensory input. This study uses the steady-state evoked response (SSR) to quantify the accuracy of timing of the neocortical response to rapidly presented tactile somatosensory stimuli in patients with schizophrenia compared to control subjects.

Abnormal gamma and beta MEG activity during finger movements in early-onset psychosis.

Patients with psychosis often exhibit abnormalities in basic motor control, but little is known about the neural basis of these deficits. This study examines the neuro-dynamics of movement using magnetoencephalography (MEG) in adolescents with early-onset psychosis and typically developing controls. MEG data were imaged using beamforming then evaluated for task and group effects before, during, and after movement onsets.

Brain size and brain/intracranial volume ratio in major mental illness.

Background: This paper summarizes the findings of a long term study addressing the question of how several brain volume measure are related to three major mental illnesses in a Colorado subject group. It reports results obtained from a large N, collected and analyzed by the same laboratory over a multiyear period, with visually guided MRI segmentation being the primary initial analytic tool.

Methods: Intracerebral volume (ICV), total brain volume (TBV), ventricular volume (VV), ventricular/brain ratio (VBR), and TBV/ICV ratios were calculated from a total of 224 subject MRIs collected over a period of 13 years.

Estimates of milk constituents from lactating bonnet macaque (Macaca radiata) mothers between two and seven months post-partum.

Background: The literature regarding milk composition in non-human primates collected across offspring development is limited. We assayed milk samples from bonnet macaque (Macaca radiata) mothers as part of studies characterizing development of this species.

Methods: Milk was obtained when possible longitudinally from seven lactating bonnet macaque mothers.

Schizoaffective disorder - a possible MEG auditory evoked field biomarker.

We recorded magnetoencephalographic auditory steady state responses (SSR) from eight schizoaffective (SAD) subjects and compared the resulting data with previously published findings in persons with schizophrenia (SZ) and controls. SAD subjects exhibited SSR responses similar to controls in the left hemisphere and greater than controls in the right hemisphere, whereas SZ subjects exhibited deficits in both amplitude and phase control in both hemispheres. Our findings suggest preservation of GABAergic inhibitory interneuronal control of layer 3 pyramidal cell activity in primary auditory cortex in SAD.

An extended motor network generates beta and gamma oscillatory perturbations during development.

This study examines the time course and neural generators of oscillatory beta and gamma motor responses in typically-developing children. Participants completed a unilateral flexion-extension task using each index finger as whole-head magnetoencephalography (MEG) data were acquired. These MEG data were imaged in the frequency-domain using spatial filtering and the resulting event-related synchronizations and desynchronizations (ERS/ERD) were subjected to voxel-wise statistical analyses to illuminate time-frequency specific activation patterns.

Fluctuation of gamma-band phase synchronization within the auditory cortex in schizophrenia.

Objective: To study the phase stability of the 40Hz auditory steady-state response (ASSR) in Sz, and in addition, to investigate inter-hemispheric phase synchronization using ipsilateral and contralateral hemisphere gamma band ASSRs.

Methods: Whole head magnetoencephalography (MEG) was used to detect ASSR from both hemispheres in Sz patients and their control counterparts. Source localization, spatial and temporal filtering were performed to infer gamma band activity from the neural generators of the ASSR.

Aberrant high-frequency desynchronization of cerebellar cortices in early-onset psychosis.

Sensorimotor integration deficits are routinely observed in both schizophreniform and mood-disordered psychoses. Neurobiological theories of schizophrenia and related psychoses have proposed that aberrations in large-scale cortico-thalamic-cerebellar-thalamic-cortical loops may underlie integration abnormalities, and that such dysfunctional connectivity may be central to the pathophysiology. In this study, we utilized a basic mechanoreception task to probe cortical-cerebellar circuitry in early-onset psychosis.

An institutional postdoctoral research training program: predictors of publication rate and federal funding success of its graduates.

Objective: The National Institute of Mental Health funds institutional National Research Service Awards (NRSA) to provide postdoctoral research training. While peer-reviewed publications are the most common outcome measure utilized, there has been little discussion of how publications should be counted or what factors impact the long-term publication rates of trainees in these programs.

Methods: The authors reviewed current curricula vitae from 92 graduates of an institutional NRSA and from the faculty mentors of that program to assess publications through 2005.

MEG auditory evoked fields suggest altered structural/functional asymmetry in primary but not secondary auditory cortex in bipolar disorder.

Objectives: Objective physiological indices independently characterizing affective and schizophreniform psychoses would contribute to our understanding of the nature of their relationships. Magnetoencephalography (MEG)-based metrics of altered structural/functional asymmetry in the superior temporal gyrus have previously been found to characterize schizophrenia at the level of both the primary auditory (AI) and the secondary auditory (AII) cortex. This study examines these markers in patients with bipolar disorder, with the goal of improved understanding of the patterns of brain asymmetry that may independently characterize affective and schizophreniform psychosis.

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

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.

Neuromagnetic evidence of broader auditory cortical tuning in schizophrenia.

Deficits in basic auditory perception have been described in schizophrenia. Previous electrophysiological imaging research has documented a structure-function disassociation in the auditory system and altered tonotopic mapping in schizophrenia. The present study examined auditory cortical tuning in patients with schizophrenia.

Neurological signs and cognitive performance distinguish between adolescents with and without psychosis.

Neurological and cognitive aspects of adolescent psychotic disorders are understudied. The authors assessed 19 adolescents with psychosis and 16 healthy comparison subjects using the Neurological Evaluation Scale (NES) and age-appropriate Wechsler intelligence quotient (IQ) scales. NES scores were highest and IQ scores were lowest among subjects with psychosis.

Aberrant functional organization and maturation in early-onset psychosis: evidence from magnetoencephalography.

Studies of the location of somatosensory and auditory cortical responses have shown anomalous hemispheric asymmetries in a variety of neurodevelopmental disorders. To date, abnormal asymmetries in the somatosensory region have shown greater specificity, being reported only in psychotic adults. This study examines the functional organization of the somatosensory cortices using magnetoencephalography in adolescents with childhood-onset psychotic disorders.

Cortical gamma generators suggest abnormal auditory circuitry in early-onset psychosis.

Neurobiological theories of schizophrenia and related psychoses have increasingly emphasized impaired neuronal coordination (i.e., dysfunctional connectivity) as central to the pathophysiology.

Regional gray matter volumetric changes in autism associated with social and repetitive behavior symptoms.

Background: Although differences in brain anatomy in autism have been difficult to replicate using manual tracing methods, automated whole brain analyses have begun to find consistent differences in regions of the brain associated with the social cognitive processes that are often impaired in autism. We attempted to replicate these whole brain studies and to correlate regional volume changes with several autism symptom measures.

Methods: We performed MRI scans on 24 individuals diagnosed with DSM-IV autistic disorder and compared those to scans from 23 healthy comparison subjects matched on age.

A voxel-based morphometry study of gray matter in parents of children with autism.

Previous structural imaging studies of autistic individuals have identified gray matter abnormalities. It remains unclear, however, which abnormalities contribute to the etiology of autism and, among these abnormalities, which reflect genetic factors. Using voxel-based morphometry, we compared regional gray matter volume in 23 parents of autistic children to an age and sex-matched control sample.

Children and adolescents with autism exhibit reduced MEG steady-state gamma responses.

Background: Recent neuroimaging studies of autism have indicated reduced functional connectivity during both cognitive tasks and rest. These data suggest long-range connectivity may be compromised in this disorder, and current neurological theories of autism contend disrupted inter-regional interactions may be an underlying mechanism explaining behavioral symptomatology. However, it is unclear whether deficient neuronal communication is attributable to fewer long-range tracts or more of a local deficit in neural circuitry.

Development of the 40Hz steady state auditory evoked magnetic field from ages 5 to 52.

Objective: Adults exhibit strong auditory 40 Hz magnetic steady state responses (SSR). Although EEG measured SSR has been studied in children, the developmental course of the magnetic SSR is unknown.

Methods: Sixty-nine healthy subjects ranging in age from 5 to 52 years participated in a magnetoencephalographic (MEG) study.

Planum temporale volume in children and adolescents with autism.

Previous research has revealed a lack of planum temporale (PT) asymmetry in adults with autism. This finding is now extended to children and adolescents with the disorder. MRI scans were obtained from 12 children with autism and 12 gender, handedness and age-matched comparison participants.

EEG correlates of methylphenidate response in ADHD: association with cognitive and behavioral measures.

The authors examined the association between EEG correlates of medication response and concomitant cognitive and behavioral changes among children with attention-deficit hyperactivity disorder (ADHD). Subjects were 36 children with ADHD, aged 8 to 12 years. EEG activity was recorded from nine active electrodes during placebo and medication conditions.

Hippocampus and amygdala volumes in parents of children with autistic disorder.

Objective: Structural and functional abnormalities in the medial temporal lobe, particularly the hippocampus and amygdala, have been described in people with autism. The authors hypothesized that parents of children with a diagnosis of autistic disorder would show similar changes in these structures.

Method: Magnetic resonance imaging scans were performed in 17 biological parents of children with a diagnosis of DSM-IV autistic disorder.

Sleep disturbance after rapid ascent to moderate altitude among infants and preverbal young children.

Rapid ascent to high altitude is known to result in sleep disturbances among adults. No data exist regarding the effects of altitude exposure on sleep in children. The objective of this study was to determine the effect of rapid ascent to moderate altitude on sleep in infants and young children.

Reduced laterality of the source locations for generators of the auditory steady-state field in schizophrenia.

Background: Reduced hemispheric asymmetry of evoked field generators in schizophrenia in secondary auditory cortex has been replicated with mixed success. This disparity is possibly due to the complex nature of the 100-msec generators typically investigated. In this study, we evaluated a source located in primary auditory cortex, responsible for the steady-state response, to determine whether similar asymmetries were present.

Anomalous somatosensory cortical localization in schizophrenia.

Objective: Schizophrenia has been reported to be associated with altered localization of regions responding to sound in the auditory cortex, suggesting possible cortical reorganization accompanying the disorder, but it is not clear whether such disturbances are present in any primary sensory cortex other than the auditory. This study examines magnetoencephalographic localization of field sources evoked by tactile stimulation generated in area 3b of the primary somatosensory cortex in patients with schizophrenia compared with normal subjects.

Method: A total of 29 subjects participated; 14 were patients with schizophrenia, and 15 were normal comparison subjects.