How brain arousal systems determine different temperament types and the major dimensions of personality

Dispositional traits help explain individual differences in relationships between a radiographic knee osteoarthritis measure, pain, and physical function

Background

The concordance between radiograph-derived Kellgren-Lawrence (KL) scores for knee osteoarthritis (KOA) and experimental and clinical pain and KOA-related physical function is conflicting.

Objectives

We investigate whether the inclusion of dispositional traits reduces variability between KOA radiographic findings, experimental pain, clinical pain, and function in individuals with knee pain.

Design

This study is a cross-sectional, secondary analysis of data collected from the UPLOAD-II study.

Methods

Adults aged 45-85 years with and without knee pain were enrolled. Data collected included sociodemographics, knee radiographs, experimental pain, clinical pain and function, and trait affect. Vulnerable and protective dispositional traits were classified from combined positive and negative trait affect measures. KL scores were determined from the knee radiographs. Unadjusted and adjusted (age, sex, comorbidities, and body mass index) regression analyses were completed with SAS version 9.4 (Cary, NC, USA).

Results

The study included 218 individuals with a mean age of 58 years, 63.6% women, and 48.2% non-Hispanic black adults. Dispositional traits were associated with the experimental pain measures. No association between radiographic KOA and experimental pain was observed. In a combined and adjusted analysis, dispositional traits were predictive of knee punctate pain temporal summation (p = 0.0382). Both dispositional traits and radiographic KOA scores independently and combined were predictive of Graded Chronic Pain Scale pain and function, and Western Ontario and McMaster University pain and function (ps ⩽ 0.01). Improvements in R2 were noted across all models with the inclusion of dispositional traits.

Conclusion

Consideration of dispositional traits reduces the variability between radiographic KOA and pain and function. Non-pathological and associated pain-related psychological factors and dispositional traits might serve as parsimonious proxy tools to improve clinical assessments.

Registration

N/A.

Vulnerable Dispositional Traits and Chronic Pain: Predisposing but not Predetermining

Dispositional traits can be protective or contribute to increased vulnerability in individuals with chronic pain. This study aims to evaluate the association between two dispositional trait measures, affect balance style and multi-domain trait groups, with psychosocial measures, clinical pain, functional pain, and experimental pain at two years in individuals with chronic knee pain. The study is a prospective analysis of 168 community dwelling individuals aged 45 to 85 years old with knee pain with or at risk for knee osteoarthritis. At baseline, affect balance style and multi-domain trait groups were associated with psychosocial measures, clinical pain, and functional status. At the two-year time point, the multi-domain trait groups were associated with the clinical pain measures. Interestingly, individuals with previously demonstrated vulnerable traits showed more variability in dispositional trait status at the two-year time point compared to those with dispositional traits previously demonstrated as more protective. Findings reiterate that dispositional traits are predisposing but are not predetermining regarding pain-related experiences. PERSPECTIVE: Vulnerable and protective dispositional traits are positively and negatively associated with clinical pain and functional limitations respectively. Although considered relatively stable, a 30-50% shift in dispositional traits was indicated over a two-year period. Findings highlight that dispositional trait are modifiable and thus, predisposing but not predetermining for persisting chronic pain.

Sympathetic arousal in children with oppositional defiant disorder and its relation to emotional dysregulation

BACKGROUND

Emotional dysregulation (ED) is a trans-nosographical condition characterized by mood instability, severe irritability, aggression, temper outburst, and hyper-arousal. Pathophysiology of emotional dysregulation and its potential biomarkers are an emerging field of interest. A Child Behaviour Checklist (CBCL) profile, defined as Dysregulation Profile (DP), has been correlated to ED in youth. We examined the association between the CBCL-DP and indices of sympathetic arousal in children with Oppositional Defiant Disorder (ODD) and healthy controls.

METHOD

The current study sought to compare the arousal level measured via electrodermal activity in response to emotional stimuli in three non-overlapping groups of children: (1) ODD+CBCL-DP (n = 28), (2) ODD without CBCL-DP (n = 35), and (3) typically developing controls (n = 25).

RESULTS

Analyses revealed a distinct electrodermal activity profile in the three groups. Specifically, children with ODD+CBCL-DP presented higher levels of sympathetic arousal for anger and sadness stimuli compared to the other two groups.

LIMITATIONS

The relatively small sample and the lack of assessing causality limit the generalizability of this study which results need to be replicated in larger, different samples.

CONCLUSION

The CBCL-DP was associated to higher levels of arousal for negative emotions, consistently with previous reports in individuals with depression and anxiety. Further work may identify potential longitudinal relationships between this profile and clinical outcomes.

Alpha band frequency differences between low-trait and high-trait anxious individuals

Trait anxiety has been shown to cause significant impairments on attentional tasks. Current research has identified alpha band frequency differences between low-trait and high-trait anxious individuals. Here, we further investigated the underlying alpha band frequency differences between low-trait and high-trait anxious individuals during their resting state and the completion of an inhibition executive functioning task. Using human participants and quantitative electroencephalographic recordings, we measured alpha band frequency in individuals both high and low in trait anxiety during their resting state, and while they completed an Eriksen Flanker Task. Results indicated that high-trait anxious individuals exhibit a desynchronization in alpha band frequency from a resting state to when they complete the Eriksen Flanker Task. This suggests that high-trait anxious individuals maintain fewer attentional resources at rest and must martial resources for task performance as compared with low-trait anxious individuals, who appear to maintain stable cognitive resources between rest and task performance. These findings add to the cognitive neuroscience literature surrounding the role of alpha band frequency in low-trait and high-trait anxious individuals.

Acute effects and after-effects of acoustic coordinated reset neuromodulation in patients with chronic subjective tinnitus

Chronic subjective tinnitus is an auditory phantom phenomenon characterized by abnormal neuronal synchrony in the central auditory system. As shown computationally, acoustic coordinated reset (CR) neuromodulation causes a long-lasting desynchronization of pathological synchrony by downregulating abnormal synaptic connectivity. In a previous proof of concept study acoustic CR neuromodulation, employing stimulation tone patterns tailored to the dominant tinnitus frequency, was compared to noisy CR-like stimulation, a CR version significantly detuned by sparing the tinnitus-related pitch range and including substantial random variability of the tone spacing on the frequency axis. Both stimulation protocols caused an acute relief as measured with visual analogue scale scores for tinnitus loudness (VAS-L) and annoyance (VAS-A) in the stimulation-ON condition (i.e. 15 min after stimulation onset), but only acoustic CR neuromodulation had sustained long-lasting therapeutic effects after 12 weeks of treatment as assessed with VAS-L, VAS-A scores and a tinnitus questionnaire (TQ) in the stimulation-OFF condition (i.e. with patients being off stimulation for at least 2.5 h). To understand the source of the long-lasting therapeutic effects, we here study whether acoustic CR neuromodulation has different electrophysiological effects on oscillatory brain activity as compared to noisy CR-like stimulation under stimulation-ON conditions and immediately after cessation of stimulation. To this end, we used a single-blind, single application, cross over design in 18 patients with chronic tonal subjective tinnitus and administered three different 16-minute stimulation protocols: acoustic CR neuromodulation, noisy CR-like stimulation and low frequency range (LFR) stimulation, a CR type stimulation with deliberately detuned pitch and repetition rate of stimulation tones, as control stimulation. We measured VAS-L and VAS-A scores together with spontaneous EEG activity pre-, during- and post-stimulation. Under stimulation-ON conditions acoustic CR neuromodulation and noisy CR-like stimulation had similar effects: a reduction of VAS-L and VAS-A scores together with a decrease of auditory delta power and an increase of auditory alpha and gamma power, without significant differences. In contrast, LFR stimulation had significantly weaker EEG effects and no significant clinical effects under stimulation-ON conditions. The distinguishing feature between acoustic CR neuromodulation and noisy CR-like stimulation were the electrophysiological after-effects. Acoustic CR neuromodulation caused the longest significant reduction of delta and gamma and increase of alpha power in the auditory cortex region. Noisy CR-like stimulation had weaker and LFR stimulation hardly any electrophysiological after-effects. This qualitative difference further supports the assertion that long-term effects of acoustic CR neuromodulation on tinnitus are mediated by a specific disruption of synchronous neural activity. Furthermore, our results indicate that acute electrophysiological after-effects might serve as a marker to further improve desynchronizing sound stimulation.

Correlations between personality traits and specific groups of alpha waves in the human EEG

Background. Different individuals have alpha waves with different wavelengths. The distribution of the wavelengths is assumed to be bell-shaped and smooth. Although this view is generally accepted, it is still just an assumption and has never been critically tested. When exploring the relationship between alpha waves and personality traits, it makes a huge difference if the distribution of the alpha waves is smooth or if specific groups of alpha waves can be demonstrated. Previous studies have not considered the possibility that specific groups of alpha waves may exist.

Methods. Computerized EEGs have become standard, but wavelength measurements are problematic when based on averaging procedures using the Fourier transformation because such procedures cause a large systematic error. If the actual wavelength is of interest, it is necessary to go back to basic physiology and use raw EEG signals. In the present study, measurements were made directly from sequences of alpha waves where every wave could be identified. Personality dimensions were measured using an inventory derived from the International Personality Item Pool.

Results. Recordings from 200 healthy individuals revealed that there are three main groups of alpha waves. These groups had frequencies around 8, 10, and 12 waves per second. The middle group had a bimodal distribution, and a subdivision gave a total of four alpha groups. In the center of each group, the degree of extraversion was high and the degree of neuroticism was low. Many small differences in personality traits were found when the centers were compared with one another. This gave four personality profiles that resemble the four classical temperaments. When people in the surrounding zones were compared with those in the centers, relatively large differences in personality traits were found.

Conclusions. Specific groups of alpha waves exist, and these groups have to be taken into account when correlations are made to personality dimensions and temperament types. There is a link between alpha waves and personality traits, and this link implies that there is an underlying relationship. To explain the nature of this relationship, there are two hypotheses that can be applied. One of these deals with the general organization of the forebrain and the other explains why the brain generates alpha waves.

Genome-Wide Association Study between Single Nucleotide Polymorphisms and Flight Speed in Nellore Cattle

Introduction

Cattle temperament is an important factor that affects the profitability of beef cattle enterprises, due to its relationship with productivity traits, animal welfare and labor safety. Temperament is a complex phenotype often assessed by measuring a series of behavioral traits, which result from the effects of multiple environmental and genetic factors, and their interactions. The aims of this study were to perform a genome-wide association study and detect genomic regions, potential candidate genes and their biological mechanisms underlying temperament, measured by flight speed (FS) test in Nellore cattle.

Materials and Methods

The genome-wide association study (GWAS) was performed using a single-step procedure (ssGBLUP) which combined simultaneously all 16,600 phenotypes from genotyped and non-genotyped animals, full pedigree information of 162,645 animals and 1,384 genotyped animals in one step. The animals were genotyped with High Density Bovine SNP BeadChip which contains 777,962 SNP markers. After quality control (QC) a total of 455,374 SNPs remained.

Results

Heritability estimated for FS was 0.21 ± 0.02. Consecutive SNPs explaining 1% or more of the total additive genetic variance were considered as windows associated with FS. Nine candidate regions located on eight different Bos taurus chromosomes (BTA) (1 at 73 Mb, 2 at 65 Mb, 5 at 22 Mb and 119 Mb, 9 at 98 Mb, 11 at 67 Mb, 15 at 16 Mb, 17 at 63 Kb, and 26 at 47 Mb) were identified. The candidate genes identified in these regions were NCKAP5 (BTA2), PARK2 (BTA9), ANTXR1 (BTA11), GUCY1A2 (BTA15), CPE (BTA17) and DOCK1 (BTA26). Among these genes PARK2, GUCY1A2, CPE and DOCK1 are related to dopaminergic system, memory formation, biosynthesis of peptide hormone and neurotransmitter and brain development, respectively.

Conclusions

Our findings allowed us to identify nine genomic regions (SNP windows) associated with beef cattle temperament, measured by FS test. Within these windows, six promising candidate genes and their biological functions were identified. These results may contribute to a better comprehension into the genetic control of temperament expression in Nellore cattle.

The Association between High Neuroticism-Low Extraversion and Dual-Task Performance during Walking While Talking in Non-demented Older Adults

The Walking While Talking (WWT) dual-task paradigm is a mobility stress test that predicts major outcomes, including falls, frailty, disability, and mortality in aging. Certain personality traits, such as neuroticism, extraversion, and their combination, have been linked to both cognitive and motor outcomes. We examined whether individual differences in personality dimensions of neuroticism and extraversion predicted dual-task performance decrements (both motor and cognitive) on a WWT task in non-demented older adults. We hypothesized that the combined effect of high neuroticism-low extraversion would be related to greater dual-task costs in gait velocity and cognitive performance in non-demented older adults. Participants (N=295; age range,=65-95 years; female=164) completed the Big Five Inventory and WWT task involving concurrent gait and a serial 7's subtraction task. Gait velocity was obtained using an instrumented walkway. The high neuroticism-low extraversion group incurred greater dual-task costs (i.e., worse performance) in both gait velocity {95% confidence interval (CI) [-17.68 to -3.07]} and cognitive performance (95% CI [-19.34 to -2.44]) compared to the low neuroticism-high extraversion group, suggesting that high neuroticism-low extraversion interferes with the allocation of attentional resources to competing task demands during the WWT task. Older individuals with high neuroticism-low extraversion may be at higher risk for falls, mobility decline and other adverse outcomes in aging.

Individual Differences in Capacity for Tolerating Information Overload Are Related to Differences in Culture and Temperament

Individual differences in the capacity for information processing in complex tasks can be predicted from both personality and temperament that derive from both the biological and social substrates of human development and behavior. If there are cultural differences in brain structure and function that govern information processing, then two different cultures may show biologically based temperamental differences in sensitivity to stimulation (e.g., Pavlov’s Strength of the Nervous System) which in turn may predict individual differences in capacity for tolerating environmentally determined stimulus overloads. We examined the relationship between biologically based measures of Pavlovian Temperament (Strength of Excitation, Inhibition, and Mobility) and an individual differences measure consisting of five dimensions of capacity for tolerating information load. Both direct and indirect effects of country of origin on capacity for information processing were tested in a mediated path analytic model in which Pavlovian Excitation, Inhibition, and Mobility were hypothesized to mediate the relationship between culture and self-reported information processing capacities.

A potential electroencephalography and cognitive biosignature for the child behavior checklist-dysregulation profile

OBJECTIVE

The Child Behavior Checklist-Dysregulation Profile (CBCL/DP) identifies youth at increased risk for significant psychopathology. Although the genetic architecture and several biological correlates of the CBCL/DP have been described, little work has elucidated its underlying neurobiology. We examined the potential utility of electroencephalography (EEG), along with behavioral and cognitive assessments, in differentiating individuals based on the CBCL/DP.

METHOD

Participants aged 7 to 14 years of age were categorized into 3 age- and sex-matched groups based on clinical assessment and CBCL/DP: typically developing controls without attention-deficit/hyperactivity disorder (ADHD) (n = 38), individuals with ADHD without the CBCL/DP (ADHD/DP-) (n = 38), and individuals with the CBCL/DP (CBCL/DP+) (n = 38). Groups were compared with EEG and measures of clinical phenomenology and cognition.

RESULTS

ADHD/DP- and CBCL/DP+ groups had increased inattention, but the CBCL/DP+ group had increased hyperactive/impulsive symptoms, disruptive behavior, mood, and anxiety comorbidities compared with the group with ADHD alone. Cognitive profiles suggested that ADHD/DP-participants had fast impulsive responses, whereas CBCL/DP+ participants were slow and inattentive. On EEG, CBCL/DP+ had a distinct profile of attenuated δ-band and elevated α-band spectral power in the central and parietal regions compared to ADHD/DP- and controls. The low-δ/high-α profile was correlated with measures of emotion and behavior problems and not with inattentive symptomatology or cognitive measures. There were no EEG differences between the ADHD/DP- and control groups.

CONCLUSIONS

An EEG/cognitive profile suggests a distinct pattern of underlying neural dysfunction with the CBCL/DP that might ultimately serve as a biosignature. Further work is required to identify potential relationships with clinically defined psychiatric disorders, particularly those of dysregulated mood.

The synchronization of spontaneous BOLD activity predicts extraversion and neuroticism

There is an increasing body of evidence pointing to a relationship between personality and brain markers. The purpose of this study was to identify the associations between personality dimensions of extraversion and neuroticism and the local synchronization of spontaneous blood oxygen level-dependent (BOLD) activity assessed by regional homogeneity (ReHo) approach. Our results revealed the significant negative correlation between neuroticism and ReHo in the left middle frontal gyrus, providing evidence for the left frontal activation involved in pleasant emotion. ReHo was correlated negatively with extraversion in the medial prefrontal cortex (MPFC), an important portion of the default mode network (DMN), thus further indicating the relationship between DMN and personality. In addition, ReHo in the insula, cerebellum and cingulate gyrus was correlated positively with extraversion, suggesting the associations between individual difference in extraversion and specific brain regions involved in affective processing. These findings shed light on the important relationship between the synchronization of spontaneous fluctuations and personality dimensions of extraversion and neuroticism, which provide further evidence for the neural underpinning of individual difference in personality traits.

Cross-frequency coupling of brain oscillations in studying motivation and emotion

Research has shown that brain functions are realized by simultaneous oscillations in various frequency bands. In addition to examining oscillations in pre-specified bands, interactions and relations between the different frequency bandwidths is another important aspect that needs to be considered in unraveling the workings of the human brain and its functions. In this review we provide evidence that studying interdependencies between brain oscillations may be a valuable approach to study the electrophysiological processes associated with motivation and emotional states. Studies will be presented showing that amplitude-amplitude coupling between delta-alpha and delta-beta oscillations varies as a function of state anxiety and approach-avoidance-related motivation, and that changes in the association between delta-beta oscillations can be observed following successful psychotherapy. Together these studies suggest that cross-frequency coupling of brain oscillations may contribute to expanding our understanding of the neural processes underlying motivation and emotion.

Cross-frequency coupling of brain oscillations: an impact of state anxiety

In recent studies, statistical relations among activities in different frequency EEG bands have been reported. Most of these studies investigate within-subject cross-frequency relations, such as amplitude-amplitude, phase-amplitude and phase-phase coupling between different frequencies. All these cross-frequency interactions are considered to be transient correlates of information processing. However, some authors suggested that a particular pattern of amplitude-amplitude relations among different frequencies may be associated with relatively stable states or even traits. Particularly delta-beta amplitude-amplitude correlation measured in the between-subject domain was shown to lawfully increase in some presumably anxiogenic conditions and in some pathological groups. The main purpose of this paper was to further explore the phenomenon of between-subject delta-beta correlation in terms of its spatial localization, relatedness to state anxiety, and similarity to within-subject amplitude-to-amplitude and phase-to-amplitude coupling. Independent component analysis was used to identify temporally correlated spatial patterns that most reliably show the phenomenon of between-subject delta-beta correlation. Results of this analysis show that in an anxiogenic situation, delta-beta correlation increases in a network of cortical areas which includes the orbitofrontal and the anterior cingulate cortices as its main node. This increase of correlation is accompanied by an increase of delta power and connectivity in the same cortical regions. Analysis of the within-subject delta-beta amplitude-to-amplitude and phase-to-amplitude coupling showed that in an anxiogenic situation, in subjects with higher scores on state anxiety they also tend to increase in the same set of cortical areas.

Reciprocal relationships between the oscillatory systems of the brain

Resting EEG recordings were made from cohorts of 146 children aged 7-17 years and 132 adults aged 18-32 years and the levels of personality features and psychopathology were assessed using the Eysenck, Spilberger, Gray-Wilson, and Goodman questionnaires. Factor analysis was used to discriminate covariance of measures of the spectral power of EEG rhythms into positive and negative components. The latter were interpreted as a measure of inhibitory interactions between oscillatory systems. In children, positive covariance of rhythms was stronger than in adults, while reciprocal relationships between oscillatory systems were weaker. In adults, trait anxiety correlated positively with the strength of the reciprocal relationship between the alpha and delta oscillatory systems. In children, an analogous relationship was seen between anxiety and the strength of the reciprocal relationship between the theta and delta systems. The data are discussed in the light of the evolutionary interpretation of EEG rhythms.

Personality differences affect brainstem autonomic responses to visceral pain

Brainstem autonomic nuclei integrate interoceptive inputs including pain, with descending modulation, to produce homeostatic and defence outputs. Cardiac Vagal Control is especially implicated in psychophysiological processes for both health and disease and is indexed non-invasively by heart rate variability. The study aim was to determine the nature of psychophysiological response profiles for visceral pain. Nineteen healthy subjects had electrocardiographic recordings at rest and during 10 painful oesophageal balloon distensions. Cardiac Vagal Control originating from nucleus ambiguus (CVC(NA)) was determined by polynomial filter application to the electrocardiogram inter-beat interval series. Heart rate and 'Cardiac Sympathetic Index (CSI)' were also determined. Psychological state and trait, including neuroticism and extroversion, were assessed. Subjects who increased CVC(NA) to pain were more neurotic, anxious and sensory sensitive than those who decreased CVC(NA.) Cluster analysis identified two psychophysiological groups: Group 1 (n = 11) demonstrated lower baseline CVC(NA) (P = 0.0001), higher heart rate (P = 0.02) and CSI (P = 0.015), pain tolerance at lower balloon volumes (P = 0.04), but attenuated heart rate response to pain (P = 0.01). Group 2 (n = 8) had the converse profile. Neuroticism scores were higher (P = 0.0004) and extroversion lower (P = 0.01) for group 1 than group 2. Two distinct psychophysiological response profiles to visceral pain exist that are influenced by personality. These may reflect different psychobiological bases for active and passive defence repertoires. Prevalence and clinical relevance of these endophenotypes as vulnerability factors for pain and emotion disorders warrant further exploration.

Is cortical distribution of spectral power a stable individual characteristic?

General understanding in EEG research is that cortical distribution of spectral power varies as a function of time, frequency, state, and experimental condition. There are findings, however, which show that individual-specific patterns of cortical spectral power distribution could be amazingly stable, at least in some experimental conditions. In this study two different experimental datasets were used to analyze stability and variability of individual pattern of cortical spectral power distribution across time, experimental conditions, and frequency bands. First experiment consisted of presentation of pictures of emotional facial expressions. Second experiment was an auditory stop-signal task. In both experiments a number of psychometric measures were obtained from each participant. It has been shown that in spite of high short-term variability, individual-specific patterns of cortical spectral power distribution are remarkably stable across frequency bands, long periods of time, and experimental conditions. These patterns are related to state and trait participant's characteristics. The antero-posterior spectral power gradient emerged as the most prominent feature associated with important personality dimensions. Relatively higher oscillatory activity in the frontal cortical region relates to female gender and Behavioral Inhibition tendencies. Relatively higher activity at posterior sites is associated with Extraversion. Significant differences in event-related spectral perturbations upon presentation of emotionally loaded stimuli were found between high and low antero-posterior gradient participants. These data show that cortical distribution of oscillatory activity may be seen as a relatively stable individual characteristic. Enhanced or diminished oscillatory activity of some cortical regions, such as the prefrontal cortex, may play an important role in organization of human behavior.

Anxiety and oscillatory responses to emotional facial expressions

In the last decade, event-related potential and functional magnetic resonance imaging studies were very useful in temporal and spatial localization of brain processes involved in the recognition of emotional facial expressions. However, frequency characteristics of the underlying processes have been less studied. Besides, most of the studies did not take into account personality-related individual differences. In this study, effects of explicit and implicit anxiety on the oscillatory dynamics of cortical responses elicited by presentation of angry, neutral, and happy faces were investigated using time-frequency decomposition by means of wavelet transform. Both explicit and implicit anxiety were associated with higher alpha band desynchronization, which was most pronounced during presentation of angry faces. Within theta and delta bands, effects appeared to be opposite for explicit and implicit anxiety measures. In implicitly anxious subjects, frontal delta and theta synchronization upon the presentation of angry and happy (but not neutral) faces was found to be higher than in low anxiety ones, whereas explicit anxiety was associated with a lower theta band synchronization. The results are discussed in terms of conscious and controlled vs. unconscious and intuitive information processing associated with explicit and implicit personality measures.

Motivation, emotion, and their inhibitory control mirrored in brain oscillations

Recent studies suggest brain oscillations as a mechanism for cerebral integration. Such integration can exist across a number of functional domains, with different frequency rhythms associated with each domain. Here, evidence is summarized which shows that delta oscillations depend on activity of motivational systems and participate in salience detection. Theta oscillations are involved in memory and emotional regulation. Alpha oscillations participate in inhibitory processes which contribute to a variety of cognitive operations such as attention and memory. The importance of inhibitory functions associated with alpha oscillations increases during the course of evolution. In ontogenesis, these functions develop later and may be more sensitive to a variety of detrimental environmental influences. In a number of developmental stages and pathological conditions, a deficient alpha and/or increased slow-wave activity are associated with cognitive deficits and a lack of inhibitory control. It is shown that slow-wave and alpha oscillations are reciprocally related to each other. This reciprocal relationship may reflect an inhibitory control over motivational and emotional drives which is implemented by the prefrontal cortex.

In pursuit of knowledge

This article is based on the proposition that to understand the nature of knowledge, and how best to acquire it, one must look first at how the brain abstracts knowledge from the information provided by sensory receptors. The nature of this biological process of knowledge acquisition is suggested by the necessary conditions for the occurrence of learning, and from consideration of these necessary conditions in terms of what is currently known about the properties and limitations of neural systems. This entails discussion of an important distinction that must be made between "perceptual" and "associative" learning and between the neural systems required to mediate these two kinds of learning. There is also discussion of the manner in which language can overcome the limitations of neurological systems to greatly extend the scope of associative learning. This leads on to discussion of the role of active efferent language systems and temporary memory in the mediation of thinking. Consideration of the main features of the biological process of knowledge acquisition confirms, and extends to perception, Hume's famous conclusion that knowledge derives from the similarity or temporal contiguity of recurring events. New insights are also obtained concerning the biological causes of bias in the knowledge acquisition process, concerning the intellectual process of theory generation, and concerning the role of theory in the conduct of empirical research. Finally, and most importantly, it can be concluded that all knowledge is theory and hence that the ultimate goal of science is the development of better theories.

The relationship of theory and methodology in EEG studies of mental activity

Due to the multidisciplinary character of psychophysiology, the problem of comparability of psychological and physiological phenomena of different natures and levels of organization has always been raised. This requires the interaction of theory and methodology to appropriately address the specifics of the psychophysiological paradigm, all the while maintaining their grounding in the actual psychological and physiological concepts. The history of EEG studies of mental activity shows that a weak theoretical basis at certain stages can result not only in methodological crises but can also affect empirical data collection and interpretation. An adequate theory can lend strong support to the methodology with "brain-oriented" structuring of psychological tasks and such a theory improves the neurophysiological informative value of the EEG parameters referring to the psychological characteristics of mental processes etc. On the other hand, the great importance of the EEG recording and processing techniques can result in overrating technological progress, hence frequently holding back meaningful interpretation and construction of a comprehensive psychophysiological conceptual framework. This in turn causes demands for higher material and intellectual outlays, due to overspecialization in research, and results in work duplication as well as the creation of a fragmentary knowledge structure. This article illustrates how the multidisciplinary interaction of theory and methodology, when focused on theoretical problems, can yield a series of concepts with escalating levels of integration, bringing together such different branches of psychophysiology as the study of functional states and of individual differences. As a result, this extends the theoretical model based on normal material to encompass borderline constitutional psychopathology.

Anxious apprehension increases coupling of delta and beta oscillations

Recent findings showing that anxiety is associated with enhanced coupling of EEG rhythms imply higher information exchange between populations of neurons associated with different oscillatory systems. In this study, influence of uncertainty on alpha-delta anticorrelation and delta-beta coupling was studied in 39 subjects (27 females) aged 19 to 30 years who also filled out the State Trait Anxiety Inventory. A measure of alpha-delta anticorrelation showed trait-like properties being uniformly higher in high trait anxiety subjects independent of experimental manipulation. Contrariwise, delta-beta coupling appeared only in anxiogenic situation both in high and low anxiety subjects.

Personality and risk of cognitive impairment 25 years later

The authors examined the relationship between personality and cognitive impairment in 4,039 members of the Swedish Twin Registry. Neuroticism and extraversion scores were collected in 1973 at midlife, and cognitive impairment was assessed in the same group 25 years later. Data were analyzed with case-control and co-twin control designs. Greater neuroticism was associated with higher risk of cognitive impairment in the results from case-control, but not from co-twin, analyses. Compared with both extraversion and introversion, moderate extraversion was associated with lower risk of cognitive impairment in both case-control and co-twin designs, as was the combination of high neuroticism and low extraversion. Findings are discussed in the context of theories related to personality, psychological distress, arousal, and cognitive function.

Personality traits and its association with resting regional brain activity

The association between personality and resting brain activity was investigated. Personality was assessed using the NEO-Five-factor Inventory (NEO-FFI) and resting brain activity was indexed by eyes closed EEG spectral magnitude from four frequency bands over the entire cortex. Results suggest that there are differences between males and females in the NEO-FFI personality traits. The NEO FFI traits were associated with lower frequency brain activity in both males and females. Mild significant and consistent associations were found between delta and theta activity across all cortical regions with Extraversion and Conscientiousness. There were few associations between personality traits and alpha and beta activity, this was shown in males only. Fewer associations between personality and faster frequency bands such as alpha may be due to the methodological problem of using fixed alpha bands. Multiple regression analyses showed that individual alpha frequencies had a greater contribution to personality traits than fixed band alpha waves.

Neuropsychologic theory and findings in attention-deficit/hyperactivity disorder: the state of the field and salient challenges for the coming decade

The past decade has witnessed the establishment of several now well-replicated findings in the neuropsychology of attention-deficit/hyperactivity disorder (ADHD), which have been confirmed by meta-analyses. Progress has been notable from the importing of cognitive science and neuroscience paradigms. Yet these findings point to many neural networks being involved in the syndrome and to modest effect sizes suggesting that any one neuropsychologic deficit will not be able to explain the disorder. In this article, leading theories and key findings are briefly reviewed in four key domains: attention, executive functions, state regulation and motivation, and temporal information processing. Key issues facing the field of neuropsychologic research and theory in ADHD include 1) the need for more integrative developmental accounts that address both multiple neural systems and the socialization processes that assure their development; 2) consideration of multiple models/measures in the same study so as to examine relative contributions, within-group heterogeneity, and differential deficit; and 3) better integration of cognitive process models with affective and temperament theories so that early precursors to ADHD can be better understood. Overall, the field has witnessed notable progress as it converges on an understanding of ADHD in relation to disruption of a multicomponent self-regulatory system. The next era must articulate multipathway, multilevel developmental accounts of ADHD that incorporate neuropsychologic effects.

Alpha oscillations as a correlate of trait anxiety

The associations among psychometric measures of anxiety and depression and individually adjusted electroencephalogram (EEG) spectral power measures registered in resting condition and during experimental settings were investigated in 30 males aged 18-25 years. During all stages of registration, Taylor Manifest Anxiety and Spielberger state anxiety (SA) and trait anxiety (TA) scores were positively related to alpha and negatively to delta relative power with these relations being independent of cortical site. Within-subject estimate of the strength of reciprocal relationship between alpha and delta oscillations (alpha-delta anticorrelation, or ADA) was positively related to trait anxiety and depression. Three minutes after an alarming event (unexpected loud sound), a further increase of alpha power was observed. In low-anxiety subjects, this increase was mostly associated with fast alpha (alpha 3), whereas in high-anxiety ones, it was mainly linked to slow alpha (alpha 2). SA mediated relationship between TA and EEG power, while ADA and alpha band reactivity showed trait-like features being associated with TA even after accounting for SA. These findings are interpreted as an indication of higher vigilance and higher reactivity of alpha system in anxious individuals.