Debora R. Baldwin

Reliability of quantitative EEG (qEEG) measures and LORETA current source density at 30 days

There is a growing interest for using quantitative EEG and LORETA current source density in clinical and research settings. Importantly, if these indices are to be employed in clinical settings then the reliability of these measures is of great concern. Neuroguide (Applied Neurosciences) is sophisticated software developed for the analyses of power, and connectivity measures of the EEG as well as LORETA current source density. To date there are relatively few data evaluating topographical EEG reliability contrasts for all 19 channels and no studies have evaluated reliability for LORETA calculations. We obtained 4 min eyes-closed and eyes-opened EEG recordings at 30-day intervals. The EEG was analyzed in Neuroguide and FFT power, coherence and phase was computed for traditional frequency bands (delta, theta, alpha and beta) and LORETA current source density was calculated in 1 Hz increments and summed for total power in eight regions of interest (ROI). In order to obtain a robust measure of reliability we utilized a random effects model with an absolute agreement definition. The results show very good reproducibility for total absolute power and coherence. Phase shows lower reliability coefficients. LORETA current source density shows very good reliability with an average 0.81 for ECB and 0.82 for EOB. Similarly, the eight regions of interest show good to very good agreement across time. Implications for future directions and use of qEEG and LORETA in clinical populations are discussed.

Resiliency and Optimism: An African American Senior Citizen’s Perspective

A total of 52 African American senior citizens (aged 59-99 years) were asked to participate in a study examining psychological resources (ego resilience and dispositional optimism) and the experience of racial stress as a function of geographical location (north vs. south). This is an understudied population, and African American seniors who remain relatively active within their respected communities may provide useful information regarding these psychological constructs in particular and successful aging in general. Participants completed the ego resilience, optimism, stress, and distress surveys. When collapsed across geographical location, resilience was negatively correlated with distress and positively correlated with optimism. Dispositional optimism was negatively correlated with levels of psychological distress. African American seniors who resided in the north reported significantly less distress than those in the south. Findings support resiliency and optimism as stress buffers for older African Americans.

Impact of differential housing on humoral immunity following exposure to an acute stressor in rats

The purpose of this study was to examine the effect of differential housing on humoral immunity following exposure to an acute stressor. Forty male Sprague-Dawley adult rats were randomly assigned to either a singly housed or group-housed (five rats/cage) condition. Approximately 2 weeks after the start of the study, all animals were immunized with 1 ml of a 10% suspension of sheep red blood cells (SRBC) in saline. After the injections, half of the animals from each housing condition were subjected to an acute stressor (forced swim, 60 min/day for 3-5 days). Animals exposed to the acute stressor displayed adrenal gland hypertrophy and reduced thymus and spleen weights compared to the unstressed (control) animals. Both behavioral stimuli (housing and forced swim) demonstrated no effect on antibody production to SRBC. However, singly housed animals showed an increase in lymphocyte percentage, and corticosterone and glucose levels regardless of subsequent exposure to acute stress. Within a treatment condition, there were no significant correlations between the immune and endocrine measures. It was concluded that reduced social contact (i.e., individual housing) with subsequent exposure to an acute stressor does not appear to inhibit immunological responsiveness to an antigen.

The Effects of Voluntary Exercise and Immobilization on Humoral Immunity and Endocrine Responses in Rats

This research examined the effect of type of stressor (physical vs. psychological) on humoral immunity and neuroendocrine responses in male and female rats. Eighty adult Sprague-Dawley rats were assigned to one of the four stress conditions (n = 20 animals/group): 1. Voluntary running (high physical/low psychological stress); 2. immobilization (low physical/high psychological stress); 3. mixed stress (running and immobilization); and 4. cage control group. The experimental manipulations were conducted over a 6-week period for 4 h/day. Five weeks after the start of the study, all animals were immunized with 1 ml of a 10% suspension of sheep red blood cells (SRBC) in saline and sacrificed 1 week later. Data analyses revealed no main effect of stress on any of the immune or endocrine parameters. However, strong gender differences emerged within the stress conditions on these physiological parameters. The stressed female rats displayed an enhanced antibody response to SRBC and a higher percentage of peripheral blood lymphocytes than their male counterparts. However, there were no significant differences between the male and female control animals with respect to these variables. Female rats consistently displayed elevated levels of plasma corticosterone and adrenal norepinephrine across all conditions. In addition, female rats displayed heavier relative organ weights (adrenal and spleen). Taken together, the notion of differential immunity with respect to physical or psychological stress is not supported by the present study.

Self-perception and Experiential Schemata in the Addicted Brain

This study investigated neurophysiological differences between recovering substance abusers (RSA) and controls while electroencephalogram (EEG) was continuously recorded during completion of a new assessment instrument. The participants consisted of 56 total subjects; 28 RSA and 28 non-clinical controls (C). The participants completed the self-perception and experiential schemata assessment (SPESA) and source localization was compared utilizing standardized low-resolution electromagnetic tomography (sLORETA). The data show significant differences between groups during both the assessment condition and baselines. A pattern of alpha activity as estimated by sLORETA was shown in the right amygdala, uncus, hippocampus, BA37, insular cortex and orbitofrontal regions during the SPESA condition. This activity possibly reflects a circuit related to negative perceptions of self formed in specific neural pathways. These pathways may be responsive to the alpha activity induced by many substances by bringing the brain into synchrony if only for a short time. In effect this may represent the euphoria described by substance abusers.

EEG Current Source Density and the Phenomenology of the Default Network

In recent years, there has been an increasing line of research dedicated to the investigation of the default mode network (DMN) of the brain and resting state networks. However, the mental activity of the DMN has not been rigorously assessed to date. The specific aims of the current study were 2-fold: First, we sought to determine whether the current source density (CSD) levels in the DMN would correspond to other neuroimaging techniques. Second, we sought to understand the subjective mental activity of the DMN during baseline recordings. This study was conducted with 63 nonclinical participants, 34 female and 29 males with a mean age of 19.2 years (standard deviation = 2.0). The participants were recorded in 8 conditions. First, 4-minute eyes-closed baseline (ECB) and eyes-opened baseline (EOB) were obtained. The participants then completed 3 assessment instruments and 3 image conditions while the electroencephalography (EEG) was continuously recorded. Participants completed subjective reports for baselines and image conditions. These were rated by 3 independent raters and compared for reliability using a random effects model with an absolute agreement definition. The mean CSD between all conditions differed significantly, in many but not all regions of interest in the DMN. Interestingly, as suggested by other studies, the DMN appears preferential to self-relevant, self-specific, or self-perceptive processes. The reliability analyses show α for interrater agreement for ECB at .95 and EOB at .96. The subjective reports obtained from the participants regarding the mental activities employed during baseline recordings correspond to attentional and self-regulatory processes, which may also implicate the resting state or DMN as playing a direct role in the maintenance of a complex behavior (eg, being still, attending, and self-regulating). Thus, attention and self-regulation constitute the phenomenology of the resting state (DMN) in this study. The results also demonstrate that EEG CSD is a useful method to examine the DMN during concept-specific tasks to elucidate the neural activity associated with these concepts. Standardized low-resolution electromagnetic tomography (sLORETA) can localize to 5 mm3, which is comparable to the findings in functional magnetic resonance imaging (fMRI). However, sLORETA can provide data about the difference in activity between groups, individuals, or populations which in many cases fMRI cannot provide.

LORETA Neurofeedback in the Precuneus Operant Conditioning in Basic Mechanisms of Self-Regulation

Low-resolution brain electomagnetic tomography (LORETA) neurofeedback provides a mechanism to influence the electrical activity of the brain in intracranial space. The aim of this study was to determine the effects of LORETA neurofeedback (LNFB) in the precuneus as a mechanism for improving self-regulation in controls and a heterogeneous diagnostic group (DX). Thirteen participants completed between 10 and 20 sessions of LNFB training in a 3-voxel cluster in the left precuneus. The participants included 5 nonclinical university students, and 8 adults with heterogeneous psychiatric diagnoses. We assessed the effects of LNFB with neurophysiological measures as well as pre- and post-Personality Assessment Inventory (PAI) subscales and selected subtests from the Delis-Kaplan Executive Function System (DKEFS). There was a significant total relative power increase at the precuneus for baseline contrasts for the control group. The DX group did not reach significant levels. All participants showed improvements in executive functions and tended to report significantly less psychopathology. The basic neural mechanisms of self-regulation are poorly understood. The data obtained in this study demonstrate that LNFB in a heterogeneous population enhances executive functions while concordantly decreasing endorsement of psychological symptoms. The alpha frequency in the brain may represent integrative functioning relative to operant efficiency and self-regulatory mechanisms.

A 9-Year-Old Boy with Multifocal Encephalomalacia: EEG Loreta and Lifespan Database, Magnetic Resonance Imaging and Neuropsychological Agreement

The methods of quantitative electroencephalography (qEEG) and LORETA current source density comparisons to the Lifespan database with Neuroguide (Applied Neuroscience Laboratories) permit a comparison of the estimated intracerebral current density distribution with LORETA. This study sought to determine the agreement between EEG LORETA, Magnetic Resonance Imaging, and Neuropsychological data for a 9-year-old boy with possible cortical damage. EEG LORETA data were collected prior to magnetic resonance imaging (MRI). Historical and current testing indicated aphasic symptoms and central auditory processing disorder. Significant impairments in verbal fluency, visual-spatial, and attentional and working memory processes are indicated, as well as profound difficulties with mathematics. MRI data indicate multifocal Encephalomalacia in bilateral prefrontal cortex, parietal lobes more pronounced in the left hemisphere, and significant volume reduction in the corpus callosum. EEG LORETA shows current source density...

The Inverse of Psychopathology: A Loreta EEG and Cortisol Examination

Low resolution electromagnetic tomography (LORETA) electroencephalogram (EEG) was recorded from 63 nonclinical adults (34 female and 29 male) while they completed inventories on self-perception (Self-Perception and Experiential Schemata) and psychological well-being (The Brief Symptom Inventory–18). In addition, salivary samples were collected before and after the self-assessment tasks for cortisol analyses. The statistical analyses revealed a significant decrease in cortisol levels from pretest to posttest self-examination. This decline in salivary cortisol was inversely correlated with greater left-sided than right-sided hemisphere activation. Self-perception and self-in-relation to others predicted resting salivary cortisol levels. These data provide further evidence for the use of LORETA EEG, in particular, as a biological marker for emotional self-regulation.

A chronic high-salt diet fails to enhance blood pressure reactivity to a tone associated with footshock, in SHR, BHR, and WKY rats

Both the human and animal literatures suggest that reactivity to stress is enhanced in the presence of a positive family history of hypertension. There is also some suggestive evidence, though not as strong, that a high-salt diet will enhance reactivity to stress, at least in a subpopulation of individuals. In the present study, rats with zero (Wistar-Kyoto, or WKY), one (borderline hypertensive, or BHR), or two (spontaneously hypertensive, or SHR) hypertensive parents were placed on a normal or high (8% in chow)-salt diet for 8 weeks starting at 8 weeks of age. After 6 weeks on the appropriate diet, rats were stressed daily for 5 days. Each session consisted of 28 foot shock trials preceded by a tone. On the following week, animals were instrumented with femoral artery catheters. After a 2-day recovery period, they were again subjected to the experimental paradigm, during which blood pressure was continuously monitored. Differences were found with respect to blood pressure reactivity and family history: SHR were the most reactive to the tone associated with foot shock. However, no effects of salt on reactivity were observed, despite an effect of this manipulation on basal blood pressure. The effect of foot shock itself was also studied, and revealed that BHR showed a blood pressure reactivity response intermediate between SHR and WKY. Once again, no effects of the salt manipulation were seen. In conclusion, while the data support a relationship between family history of hypertension and reactivity to stress, they do not support a relationship between salt intake and reactivity to stress.(ABSTRACT TRUNCATED AT 250 WORDS)