Biomedical subjects

Evian Gordon

Publications and source records attributed to Evian Gordon.

At least 55 records · Page 3Linked to original sources

PubMed2005

Distinct pattern of P3a event-related potential in borderline personality disorder.

P3a and P3b event-related brain potentials to auditory stimuli were recorded for 17 unmedicated patients with borderline personality disorder, 17 matched healthy controls and 100 healthy control participants spanning five decades. Using high-resolution fragmentary decomposition for single-trial event-related potential analysis, distinctive disturbances in P3a in borderline personality disorder patients were found: abnormally enhanced amplitude, failure to habituate and a loss of temporal locking with P3b. Normative age dependencies from 100 controls suggest that natural age-related decline in P3a amplitude is reduced in borderline personality disorder patients and is likely to indicate failure of frontal maturation. On the basis of the theories of Hughlings Jackson, this conceptualization of borderline personality disorder is consistent with an aetiological model of borderline personality disorder.

Acoustic Stimulation↗

PubMed2005

BOLD, sweat and fears: fMRI and skin conductance distinguish facial fear signals.

It is not known how the brain and autonomic systems interact during perception of facial signals of danger. We recorded blood-oxygen-level-dependent (BOLD) activity using fMRI and simultaneous skin conductance measures of autonomic arousal in healthy subjects. Distinct response profiles were elicited for fear (enhanced arousal with amygdala activity), anger (rapid onset, slow recovery arousal responses with anterior cingulate) and disgust (delayed arousal responses with insula and basal ganglia activity). The findings suggest that fear, anger and disgust perception involves specific interactions in the neural arousal systems for emotion and motivation.

Adult↗

PubMed2005

A direct brainstem-amygdala-cortical 'alarm' system for subliminal signals of fear.

We examined whether consciously undetected fear signals engage a collateral brainstem pathway to the amygdala and prefrontal cortex in the intact human brain, using functional neuroimaging. 'Blindsight' lesion patients can respond to visual fear signals independently from conscious experience, suggesting that these signals reach the amygdala via a direct pathway that bypasses the primary visual cortex. Electrophysiological evidence points to concomitant involvement of prefrontal regions in automatic orienting to subliminal signals of fear, which may reflect innervation arising from brainstem arousal systems. To approximate blindsight in 22 healthy subjects, facial signals of fear were presented briefly (16.7 ms) and masked such that conscious detection was prevented. Results revealed that subliminal fear signals elicited activity in the brainstem region encompassing the superior colliculus and locus coeruleus, pulvinar and amygdala, and in fronto-temporal regions associated with orienting. These findings suggest that crude sensory input from the superior colliculo-pulvinar visual pathway to the amygdala may allow for sufficient appraisal of fear signals to innervate the locus coeruleus. The engagement of the locus coeruleus could explain the observation of diffuse fronto-temporal cortical activity, given its role in evoking collateral ascending noradrenergic efferents to the subcortical amygdala and prefrontal cortex. This network may represent an evolutionary adaptive neural 'alarm' system for rapid alerting to sources of threat, without the need for conscious appraisal.

Adult↗

PubMed2005

Preservation of limbic and paralimbic structures in aging.

Patterns of gray matter (GM) loss were measured in 223 healthy subjects spanning eight decades. We observed significant clusters of accelerated loss in focal regions of the frontal and parietal cortices, including the dorsolateral frontal cortex, pre- and postcentral gyrus, and the inferior and superior parietal lobes. The rate of loss in these clusters was approximately twice that of the global average. By contrast, clusters of significant GM preservation were found in limbic and paralimbic structures, including the amygdala, hippocampus, thalamus, and the cingulate gyrus. In these clusters, GM loss was attenuated significantly relative to the global rate. The preservation of these structures is consistent with the functional importance of the thalamo-limbic circuits in sensory integration, arousal, emotion, and memory, and lends credence to the idea that later-maturing cortical regions are more vulnerable to age-related morphologic changes. Moreover, the limbic findings act as a frame of reference to explore further the effects of stress and learning on these structures in an evidence-based manner across age.

Adolescent↗

PubMed2005

Category and letter verbal fluency across the adult lifespan: relationship to EEG theta power.

The purpose of this study was to examine the impact of age, sex, and education on category and letter verbal fluency task performance. A secondary goal was to examine whether resting EEG theta power in bilateral frontal and temporal lobes impacts age-associated decline in verbal fluency task performance. A large sample (N = 471) of healthy, normal participants, age 21-82, was assessed for letter fluency (i.e., FAS), and for category fluency (i.e., Animal Naming), and with a 32-channel EEG system for 'eyes-open' resting theta power. The effects of age, sex, and education were examined using analyses of variance. Correlation analyses were used to test the impact of theta power on age and fluency performance by controlling for the effects of theta when examining the relationship between the other two variables. The results indicated that performance on both fluency tests declined linearly with age, but that the rate of decline was greater for category fluency. These age changes were not associated with education level, and there were no sex differences. While theta power was negatively associated with age and positively associated with Animal Naming performance, it did not moderate the relationship between the two. The differential age-associated decline between category and letter fluency suggests separate neurobiological substrates underlying the two domains of performance, which is not related to theta activity.

Adult↗

PubMed2005

Subcortical hyperintensities impact cognitive function among a select subset of healthy elderly.

Previous studies have examined the impact of subcortical hyperintensities (SH), a proxy measure of cerebrovascular disease, on the cognitive abilities of otherwise healthy older adults. However, there remains a limited understanding as to what extent this MRI marker of pathological processes explains the decline in specific cognitive functions that occur nearly ubiquitously with advanced age, especially in relation to other age-related imaging markers. In the present study we compared cognitive abilities between a sample of 53 older healthy adults (age range=50-79) and a sample of 53 younger adults (age range=21-40). As expected, the older group performed significantly worse on most cognitive measures compared to the younger group. Frontal volume and total grey matter volume were also significantly reduced among the older individuals compared to the younger individuals. SH volume was consistently associated with cognitive function in older adults, though, this relationship was evident only for a relatively small subset of older individuals with the most severe SH. These data suggest that the relationship between SH and cognition in the elderly is driven by a subset of individuals who may be in the earliest stages of vascular cognitive impairment. Further, the findings suggest that cognitive aging is largely determined by factors other than SH for most older adults.

Adolescent↗

PubMed2005

Responses to methylphenidate in adolescent AD/HD: evidence from concurrently recorded autonomic (EDA) and central (EEG and ERP) measures.

This paper aims to examine the effects of methylphenidate (MPH) on integrated baseline and event-related psychophysiological measures in AD/HD. Thirty-four unmedicated AD/HD adolescents (11-17 years; 6 females) were first compared to 34 age- and sex-matched controls, and then re-tested at least 4 weeks after methylphenidate (MPH) medication. In each testing session, EDA was recorded simultaneously with EEG during a resting eyes open condition, and with ERPs during an auditory oddball task. Unmedicated AD/HD subjects were compared to controls and then AD/HD subjects were compared pre- and post-medication. Correlations between the change in EEG theta and the remaining psychophysiological variables were undertaken to provide information about post MPH treatment changes. In the unmedicated state, AD/HD was characterized by abnormally enhanced theta, across fronto-central sites, generally reduced P2 responses, with larger non-specific and oddball-elicited SCRs and poor behavioural performance on the oddball task. Following treatment, AD/HD showed a 'normalization' of theta activity (particularly in the right hemisphere), a reduction in the rate of decrement of EDA and a general increase in P3 amplitude. These findings suggest that methylphenidate is associated with a robust 'normalization' of low frequency EEG activity during the resting brain state, but has less impact on task-related brain activity or phasic changes in autonomic function. This dissociation of resting and task-related activity may prove to be useful in elucidating the effects of stimulant versus new non-stimulant medications in AD/HD.

Adolescent↗

PubMed2005

Resting EEG theta activity predicts cognitive performance in attention-deficit hyperactivity disorder.

Quantitative electroencephalography has contributed significantly to elucidating the neurobiologic mechanisms of attention-deficit hyperactivity disorder. The most consistent and robust electroencephalographic disturbance in attention-deficit hyperactivity disorder has been abnormally increased theta band during resting conditions. Separate research using attention-demanding tests has elucidated cognitive disturbances that differentiate attention-deficit hyperactivity disorder. This study attempts to integrate electroencephalographic and neuropsychological indices to determine whether cognitive performance is specifically related to increased theta. Theta activity was recorded during a resting condition for 46 children/adolescents with attention-deficit hyperactivity disorder and their sex- and age-matched control subjects. Accuracy and reaction time during an auditory oddball and a visual continuous performance test were then recorded. Compared with control subjects, the attention-deficit hyperactivity disorder group manifested significantly increased (primarily left) frontal theta. Furthermore, the attention-deficit hyperactivity disorder group scored significantly delayed reaction time and decreased accuracy in both tasks. Correlation analysis revealed a significant relationship between frontal (primarily left) theta and oddball accuracy for the attention-deficit hyperactivity disorder group compared with a significant relationship between posterior (primarily right) theta and reaction time in the continuous performance test for the control group. These results indicate that spatial neurophysiologic deficits in attention-deficit hyperactivity disorder may be related to disturbances in signal detection. This observation has important implications for the role of trait-like biologic deficits in attention-deficit hyperactivity disorder predicting performance in information processing.

Adolescent↗

PubMed2005

Preliminary validity of "integneuro": a new computerized battery of neurocognitive tests.

The purpose of this study was to examine the preliminary validity of a newly developed battery of computerized cognitive measures, IntegNeuro. This standardized and semi-automated computerized battery assesses sensori-motor function, attention, new learning and memory, language fluency, executive function, and estimated intelligence. A total of 50 healthy individuals (aged 22-80 years) were included in the study. Correlational analyses revealed highly significant associations between the two cognitive batteries. These results support the use of IntegNeuro as a computerized cognitive system. Additional studies are needed to examine the clinical utility of the battery.

Adult↗

PubMed2005

Predicting stimulant medication response in ADHD: evidence from an integrated profile of neuropsychological, psychophysiological and clinical factors.

There have been significant advances in understanding the neurobiology of Attention-Deficit/Hyperactivity Disorder (ADHD) and it is timely to examine the ability of biological and psychological markers to predict medication response in this disorder. We evaluated prediction of medication response in adolescent ADHD using neuropsychological testing and psychophysiological measures of central and autonomic function. Fifty ADHD adolescents participated in pre- and post-stimulant medication testing. Separately ranked performance in auditory oddball and visual Working Memory (WM) tasks determined 20 "responders" and 20 "non-responders" with 10 "neutrals" excluded from the discriminant function analyses (DFA). For both oddball and WM performance rankings, the two groups did not differ in age, sex, or handedness. However, responders did have higher levels of symptomatology than non-responders at baseline. Pre-stimulant medication psychophysiology variables were used as predictors in each DFA. Oddball performance correctly classified 85.0% of responders and 95.0% of non-responders. Better response was associated with increased resting beta power (left posteriorly), delayed oddball target N1 (frontally), decreased oddball target P2 (left posteriorly) and decreased WM distractor P3 (right frontally). Working memory performance classified 80.0% of responders and 90.0% of non-responders, with a broadly similar profile of psychophysiological predictors. These finding indicate the value of integrating neuropsychological and psychophysiological data in predicting medication response in ADHD.

Adolescent↗

PubMed2005

Toward an integrated profile of depression: evidence from the brain resource international database.

Clinical depression is one of the most common psychiatric disorders in adults, yet non-clinical depression in the community may go unnoticed, despite high prevalence rates and significant psychosocial impairment. The aim of the current study was to classify 1,226 individuals from a community sample on the basis of depression scores (using the Depression Anxiety Stress Scales, DASS) and to determine whether depression in a non-clinical sample differed significantly from healthy controls on a profile of multimodal measures. The data analyzed in this study included personality, emotional intelligence, cognition and psychophysiology. It was predicted that non-clinically depressed participants would differ from healthy controls on measures of personality (increased neuroticism; decreased extraversion), emotional intelligence (decreased), cognition (impairments in executive dysfunction and memory impairment), psychophysiology (increased resting-state, right-frontal activation; diminished skin conductance) after controlling for gender, age, handedness and years of education. Findings provide support for the majority of hypotheses, though no evidence was found for memory impairment or frontal hemispheric asymmetry. Longitudinal studies are needed to determine the extent to which of these findings will have utility for the prediction of depression onset and treatment response/non-response.

Adult↗

PubMed2005

Toward an integrated profile of emotional intelligence: introducing a brief measure.

Over the last decade, an increasing number of research studies have focused on the construct of Emotional Intelligence (EI), which may be broadly defined as the capacity to perceive and regulate emotions in oneself as well as those of others. Researchers have generally adopted an organizational or management focus to the study of EI, however studies which adopt a more integrated perspective by combining psychological with biological measures, may help in further elucidating this relatively abstract construct. The first objective of this paper was to report on the psychometric properties of a brief, self-report measure of EI (Brain Resource Inventory for Emotional intelligence Factors or BRIEF), comprising internal emotional capacity (IEC), external emotional capacity (EEC) and self concept (SELF). Second, we further explored the validity of the measure by assessing the relationships between the BRIEF and variables considered relevant to the understanding of EI (including gender, age, personality, cognitive intelligence and resting state electroencephalography, EEG). The BRIEF possessed sound psychometric properties (internal consistency, r=0.68-0.81; test-retest reliability, r=0.92; construct validity with the Self Report Emotional Intelligence Test, r=0.70). As hypothesized, females were found to score higher than males on EI. EI was associated more with personality than with cognitive ability, and EEG was found to explain a significant portion of the variance in EI scores. The finding that low EI is related to underarousal of the left-frontal cortex (increased theta EEG) is consistent with research on patients with depression, as well as attention deficit hyperactivity disorder. Although EI did not display age-related increases, this might relate to the exclusion of adolescents from our sample. In conclusion, examination of the way in which EI measures relate to a complementary range of psychological and biological measures may help to further elucidate this construct.

Adult↗

PubMed2005

The impact of early life stress on psychophysiological, personality and behavioral measures in 740 non-clinical subjects.

Early Life Stress (ELS) has been associated with a range of adverse outcomes in adults, including abnormalities in electrical brain activity [1], personality dimensions [40], increased vulnerability to substance abuse and depression [14]. The present study seeks to quantify these proposed effects in a large sample of non-clinical subjects. Data for the study was obtained from The Brain Resource International Database (six laboratories: two in USA, two in Europe, two in Australia). This study analyzed scalp electrophysiological data (EEG eyes open, closed and target auditory oddball data) and personality (NEO-FFI), history of addictive substance use and ELS) data that was acquired from 740 healthy volunteers. The ELS measures were collected via a self-report measure and covered a broad range of events from childhood sexual and physical abuse, to first-hand experience of traumatizing accidents and sustained domestic conflict [41]. Analysis of covariance, controlling for age and gender, compared EEG data from subjects exposed to ELS with those who were unexposed. ELS was associated with significantly decreased power across the EEG spectrum. The between group differences were strongest in the eyes closed paradigm, where subjects who experienced ELS showed significantly reduced beta (F1,405=12.37, p=.000), theta (F1,405=20.48, p=.000), alpha (F1,405=9.65, p=.002) and delta power (F1,450=36.22, p=.000). ELS exposed subjects also showed a significantly higher alpha peak frequency (F1,405=6.39, p=.012) in the eyes closed paradigm. Analysis of covariance on ERP components revealed that subjects who experienced ELS had significantly decreased N2 amplitude (F1,405=7.73, p=.006). Analyses of variance conducted on measures of personality revealed that subjects who experienced ELS had significantly higher levels of neuroticism (F1,264=13.39, p=.000) and openness (F1,264=17.11, p=.000), but lower levels of conscientiousness, than controls (F1,264=4.08, p=.044). The number of ELS events experienced was shown to be a significant predictor of scores on the DASS questionnaire [27], which rates subjects on symptoms of depression (F3,688=16.44, p=.000, R2=.07), anxiety (F3,688=14.32, p=.000, R2=.06) and stress (F3,688=20.02, p=.000, R2=.08). Each additional early life stressor was associated with an increase in these scores independent of age, gender and the type of stressor. Furthermore, the number of ELS experiences among smokers was also found to be a positive predictor of the nicotine dependency score (Faegstrom Test For Nicotine Dependence, [19]) (F3,104=10.99, p=.000, R2=.24), independent of age, gender and type of stressor. In conclusion, we highlight the impact of a history of ELS showed significant effects on brain function (EEG and ERP activity), personality dimensions and nicotine dependence.

Adolescent↗

PubMed2005

Age-dependent change in executive function and gamma 40 Hz phase synchrony.

Decline in cognitive function is well recognized, yet few neurophysiological correlates of age-related cognitive decline have been identified. In this study we examined the impact of age on neurocognitive function and Gamma phase synchrony among 550 normal subjects (aged 11-70). Gamma phase synchrony was acquired to targets in the auditory oddball paradigm. The two tasks of executive function were switching of attention and an electronic maze. Subjects were divided into four age groups, which were balanced for sex. We hypothesized that reduced cognitive performance among older healthy individuals would be associated with age-related changes in gamma phase synchrony. Results showed a significant decrease in executive function in the oldest (51-70 years) age group. ANOVAs of age-by-frontal Gamma synchrony also showed a significant effect of age on Gamma phase synchrony in the left frontal region that corresponded modestly to the age effect found on executive task performance, with reduced performance associated with increased gamma synchrony. The results indicate that age-related changes in cognitive function evident among elderly individuals may in part be related to decreased ability to integrate information and this may be reflected as a compensatory increase in gamma synchrony in frontal regions of the brain.

Adolescent↗

PubMed2005

Integrative assessment of brain and cognitive function in post-traumatic stress disorder.

The present study combined neuropsychological and electrophysiological measures to obtain a comprehensive profile of the everyday attentional and memory dysfunction reported in PTSD. The event-related potential (ERP) literature has consistently found abnormalities in late components (N2, P3) reflecting working memory (WM) function. However, the neuropsychological profile reported in the literature has considerable variation. The present study examined ERP activity in 33 PTSD participants and matched controls during a standard two-tone auditory oddball task. Neuropsychological assessment was carried out using a task battery assessing a wide range of cognitive functions. Consistent with previous work, the PTSD group showed delayed N2 latency and reduced P3 target amplitude, together with slower and less accurate target detection. Scalp topography provided evidence of widespread abnormality during WM function, but with strongest effects broadly over the left hemisphere. Neuropsychological testing found concomitant difficulties on factorial measures of verbal memory retention/access and sustained attention but enhanced performance on measures of immediate recall. This integrative pattern of effects reflects a specific impairment in the operation of working memory systems that guide ongoing, planned behavior and that facilitate the acquisition and retention of new memories.

Adult↗

PubMed2005

Neural synchrony and gray matter variation in human males and females: integration of 40 Hz gamma synchrony and MRI measures.

Coherent cognition requires activity to be brought together across diverse brain networks. Synchronous, in-phase oscillations in the high-frequency (40 Hz) Gamma range are thought to be one mechanism underlying the functional integration of brain networks. While sex differences have been observed across a range of cognitive functions, their role in normal cortical synchronization has not been elucidated. We recorded Gamma phase synchrony in 500 male and 500 female subjects during an auditory oddball task, which taps discrimination of task-relevant signals. Results revealed a marked sex-linked dissociation in the spatio-temporal pattern of cortical synchronization. Females showed increased Gamma synchrony in the frontal brain, while males showed enhanced synchrony in the parieto-occipital region. These differences were not accounted for by sex differences in whole brain MRI volume. However, there were positive associations between Gamma synchrony and gray matter for females, while these relationships were negative for males. Sex differences in the profile of cortical synchronization may reflect distinct aspects of evolutionary advantage.

Adult↗

PubMed2005

The dose-dependent effect of methylphenidate on performance, cognition and psychophysiology.

The effects of methylphenidate (MPH) on 32 healthy human male volunteers (aged 18 to 25 years, mean age=22.26) were examined using a within-subject design. Each participant attended six testing periods, held once per week. Within each testing period, three repeat testing sessions were undertaken: pre-medication, on-medication and two hours post-medication. In these sessions, dose was manipulated (placebo, 5 mg, 15 mg or 45 mg) according a double-blind placebo design. In this report, we focus on behavioral, autonomic arousal (heart rate, skin conductance) and psychophysiological (ERP) data acquired during the working memory task. We found increased autonomic arousal (heart rate, skin conductance and blood pressure) with MPH. A linear reduction in reaction time, omission errors and target P3 latency, and a corresponding increase in background P3 amplitude was observed with increased MPH dose. The relationship between these measures supported an increase in performance and underlying brain function with MPH. To our knowledge, this is the first paper to use behavioral, arousal and electrophysiological measures in an integrative approach to study the effects of MPH on healthy adults.

Adolescent↗

PubMed2005

"Gamma synchrony" in first-episode schizophrenia: a disorder of temporal connectivity?

OBJECTIVE: There has been a convergence of models describing schizophrenia as a disconnection syndrome, with a focus on the temporal connectivity of neural activity. Synchronous gamma-band (40-Hz) activity has been implicated as a candidate mechanism for the binding of distributed neural activity. To the authors' knowledge, this is the first study to investigate "gamma synchrony" in first-episode schizophrenia. METHOD: Forty medicated first-episode schizophrenia patients and 40 age- and sex-matched healthy comparison subjects participated in a conventional auditory oddball paradigm. Gamma synchrony, time-locked to target stimuli, was extracted from an ongoing EEG. The magnitude and latency of both early (gamma 1: -150 msec to 150 msec poststimulus) and late (gamma 2: 200 to 550 msec poststimulus) synchrony were analyzed with multiple analysis of variance. RESULTS: First-episode schizophrenia patients showed a decreased magnitude and delayed latency for global gamma 1 synchrony in relation to healthy comparison subjects. By contrast, there were no group differences in gamma 2 synchrony. CONCLUSIONS: These findings suggest that first-episode schizophrenia patients have a global decrease and delay of temporal connectivity of neural activity in early sensory response to task-relevant stimuli. This is consistent with cognitive evidence of perceptual integration deficits in this disorder and raises the possibility that a breakdown in the early synchrony of distributed neural networks is a marker for the onset of schizophrenia.

Acoustic Stimulation↗