Kerry L. Coburn

Effects of aerobic exercise and gender on visual and auditory P300, reaction time, and accuracy

Abstract Visual and auditory reaction times (RTs) have been reported to decrease during moderate aerobic exercise, and this has been interpreted as reflecting an exercise-induced activation (EIA) of cognitive information processing. In the present study we examined changes in several independent measures of information processing (RT, accuracy, P300 latency and amplitude) during exercise, and their relationship to visual or auditory modalities and to gender. P300 latencies offer independent measures of cognitive speed that are unrelated to motor output, and P300 amplitudes have been used as measures of attentional allocation. Twenty-four healthy college students [mean (SD) age 20 (2) years] performed auditory and visual “oddball” tasks during resting baseline, aerobic exercise, and recovery periods. Consistent with previous studies, both visual and auditory RTs during exercise were significantly shortened compared to control and recovery periods (which did not differ from each other). We now report that, paralleling the RT changes, auditory and visual P300 latencies decreased during exercise, indicating the occurrence of faster cognitive information processing in both sensory modalities. However, both auditory and visual P300 amplitudes decreased during exercise, suggesting diminished attentional resource allocation. In addition, error rates increased during exercise. Taken together, these results suggest that the enhancement of cognitive information processing speed during moderate aerobic exercise, although operating across genders and sensory modalities, is not a global facilitation of cognition, but is accompanied by decreased attention and increased errors.

P300 delay and attenuation in schizophrenia : Reversal by neuroleptic medication

BACKGROUND P300 amplitude reduction in schizophrenia has been found by many investigators, but P300 latency generally has been reported to be normal; however, conflicting findings are present in the literature, and interpretation has been confounded by medication effects and methodological differences. METHODS This study used a standard auditory oddball paradigm to compare the latency, amplitude, and topographic distribution of P300s in neuroleptic-free schizophrenic patients with those of healthy controls. The patients then were treated for 6 weeks with either remoxipride or haloperidol, and their P300s were reassessed. RESULTS P300s were attenuated and delayed among neuroleptic-free patients. There was no evidence of peak lateralization or amplitude asymmetry over temporal areas. Subsequent neuroleptic medication normalized P300 latencies and increased P300 amplitudes, but the latter remained below normal limits over all except frontal areas. There were no correlations between P300 latency or amplitude and clinical symptomatology either before or after treatment. CONCLUSIONS The finding of a P300 delay in neuroleptic-free schizophrenics that is normalized by neuroleptic medication has not been reported previously. Neuroleptic effects on P300 amplitude and latency appear to be independent of effects on clinical symptoms, and cannot be attributed to anticholinergic activity.

Altered EEG Dynamical Responsivity Associated with Normal Aging and Probable Alzheimer's Disease

The Takens-Ellner method was employed to estimate the dimensional complexity of topographic EEG data (resting, eyes-closed and eyes-open) in 3 subject groups: normal young, normal elderly, and elderly

Association of the brain-derived neurotrophic factor Val66Met polymorphism with hippocampus volumes in drug-free depressed patients.

Abstract Objectives. Val66Met BDNF gene polymorphism is shown to affect the function of mature BDNF and mature BDNF plays an important role in the hippocampal neurogenesis and neuronal survival. Methods. A relationship of Val66Met BDNF gene polymorphism and hippocampal volumes in 33 MDD patients and 40 healthy controls is investigated. Region of interest analysis was conducted on the images acquired via MRI. Results. Depressed patients had smaller left hippocampal volumes compared to healthy controls. The diagnosis of MDD was not significantly related to hippocampal volumes among Met carriers; however, among Val homozygotes depressed patients had significantly smaller left hippocampal volumes compared to controls. Although both right and left hippocampal volumes showed nearly significant correlation with the duration of illness, this correlation reached (negative) significant levels only in the right hippocampal volume of the Val homozygotes. Conclusions. Val homozygote genotype may serve as a vulnerability factor in MDD regarding hippocampal volume loss. This finding can be considered as a supportive evidence for the neurotrophic factor hypothesis of depression.

Reduced left uncinate fasciculus fractional anisotropy in deficit schizophrenia but not in non-deficit schizophrenia

Aims:  Schizophrenia is a psychiatric disorder manifesting with heterogeneous symptom clusters and clinical presentations. The deficit syndrome is the condition defined by the existence of primarily negative symptoms, and patients with the deficit syndrome differ from non‐deficit patients on measures of brain structure and function. In the current study, by using diffusion tensor imaging (DTI), we investigated the frontotemporal connectivity that is hypothesized to differ between deficit and non‐deficit schizophrenia.

Cerebral blood flow, metabolic, receptor, and transporter changes in bipolar disorder: the role of PET and SPECT studies.

The basic concepts of positron emission tomography (PET) and single photon emission computed tomography (SPECT) scanning are introduced, and the two modalities are compared. Applications to bipolar disorder (BD) are reviewed. Regional cerebral metabolic rate and blood flow, often used as surrogate measures of neuronal synaptic activity, are increased in the frontal lobes in both unipolar and bipolar depression. In mania, metabolism increases in the dorsal cingulate cortex, striatal regions, and the nucleus accumbens, as well as in limbic structures of the temporal lobes, but decreases in dorsolateral prefrontal cortex, possibly reflecting its loss of modulatory control over limbic structures. Specifically targeted PET radioligands are used to investigate neurotransmitter systems. D1 receptor binding potentials are reduced in frontal cortex, but striatal D2 receptor density is normal in all phases of non-psychotic BD. Psychotic BD patients show higher D2 receptor densities in the caudate, which correlate with the degree of psychosis but not mood symptoms. The serotonin transporter shows increased density in the thalamus, dorsal cingulate cortex, medial preftontal cortex, and insula of depressed BD patients. In the dorsal cingulate cortex and insula, it correlates with anxiety (and in the cingulate, with suicide attempts).

Evaluation of traumatic brain injury: Brain potentials in diagnosis, function, and prognosis

The focus of this review is an analysis of the use of event-related brain potential (ERP) abnormalities as indices of functional pathophysiology in survivors of traumatic brain injury (TBI). TBI may be the most prevalent but least understood neurological disorder in both civilian and military populations. In the military, thousands of new brain injuries occur yearly; this lends considerable urgency to the use of highly sensitive ERP tools to illuminate brain changes and to address remediation issues. We review the processes thought to be indexed by the cognitive components of the ERP and outline the rationale for applying ERPs to evaluate deficits after TBI. Studies in which ERPs were used to clarify the nature of cognitive complaints of TBI survivors are reviewed, emphasizing impairment in attention, information processing, and cognitive control. Also highlighted is research on the application of ERPs to predict emergence from coma and eventual outcome. We describe primary blast injury, the leading cause of TBI for active duty military personnel in present day warfare. The review concludes with a description of an ongoing investigation of mild TBI, aimed at using indices of brain structure and function to predict the course of posttraumatic stress disorder. An additional goal of this ongoing investigation is to characterize the structural and functional sequelae of blast injury.

Brain regions associated with risk and resistance for bipolar I disorder: a voxel‐based MRI study of patients with bipolar disorder and their healthy siblings

Bipolar I disorder is a highly heritable disorder but not all siblings manifest with the illness, even though they may share similar genetic and environmental risk factors. Thus, sibling studies may help to identify brain structural endophenotypes associated with risk and resistance for the disorder.

Pharmacological Management of Persistent Hostility and Aggression in Persons With Schizophrenia Spectrum Disorders: A Systematic Review

The incidence of aggressive behaviors is higher among persons with schizophrenia spectrum disorders (SSDs) than among persons without such disorders. This phenomenon represents a risk to the well-being of patients, their families, and society. The authors undertook a systematic review of the English language literature to determine the efficacy of neuropharmacological agents for the management of hostility and aggression among persons with SSDs. The search combined findings from the Medline, EMBASE, and PsycINFO databases. Ninety-two full text articles were identified that reported relevant findings. The American Academy of Neurology criteria were used to determine levels of evidence. Paliperidone-extended release is probably effective for the management of hostility among inpatients with SSDs who have not been preselected for aggression (Level B). Clozapine is possibly more effective than haloperidol for the management of overt aggression and possibly more effective than chlorpromazine for the management of hostility among inpatients with SSDs who have not been preselected for aggression (Level C). Clozapine is also possibly more effective than olanzapine or haloperidol for reducing aggression among selected physically assaultive inpatients (Level C). Adjunctive propranolol, valproic acid, and famotidine are possibly effective for reducing some aspects of hostility or aggression among inpatients with SSDs (Level C). Paliperidone-extended release currently appears to be the agent for the management of hostility among inpatients with SSDs for which there is the strongest evidence of efficacy.

Concurrent visual task effects on evoked and emitted auditory p300 in adolescents

Using an oddball stimulus presentation paradigm, the effects of divided attention on auditory P300s were studied. Auditory attention was either divided or focused, depending on the demands placed on subjects during the performance of a concomitantly presented visual task. Two types of auditory tasks were performed under each of the two auditory attention conditions. In one, subjects responded to infrequently presented high pitched tones (oddball stimuli). In the other they responded to the occasional omission of a stimulus in an otherwise rhythmically presented chain of stimuli. P300s and reaction times were recorded to both the rare tones and the omissions. The Sternberg visual memory task was used to manipulate the subjects auditory attention state. Subjects actively performed the Sternberg task during the divided auditory attention condition, whereas during the focused attention condition they were not required to respond to the visual stimuli. During focused auditory attention, evoked auditory P300s were both larger and faster than their emitted counterparts. During divided attention, auditory P300s were reduced in amplitude but latency was unaffected. Evoked auditory P300s showed evidence of containing P300a as well as P300b components, particularly when attention was shared with the visual task.