Showing papers by "Richard J. Davidson published in 1998"

Affective Style and Affective Disorders: Perspectives from Affective Neuroscience

Abstract: Individual differences in emotional reactivity or affective style can be decomposed into more elementary constituents. Several separable of affective style are identified such as the threshold for reactivity, peak amplitude of response, the rise time to peak and the recovery time. latter two characteristics constitute components of affective chronometry The circuitry that underlies two fundamental forms of motivation and and withdrawal-related processes-is described. Data on differences in functional activity in certain components of these are next reviewed, with an emphasis on the nomological network of surrounding individual differences in asymmetric prefrontal The relevance of such differences for understanding the nature affective dysfunction in affective disorders is then considered. The ends by considering what the prefrontal cortex “does” in certain of affective style and highlights some of the important questions for future research.

Anterior electrophysiological asymmetries, emotion, and depression: Conceptual and methodological conundrums

Abstract: Two reports in the last issue of this journal attempted to replicate aspects of our previous studies on anterior electroencephalogram (EEG) asymmetry, affective style, and depression. In this commentary, an overview is provided of our model of anterior asymmetries, affective style, and psychopathology. Emphasis is placed on conceptualizing the prefrontal and anterior temporal activation patterns within a circuit that includes cortical and subcortical structures. The causal status of individual differences in asymmetric activation in the production of affective style and psychopathology is considered. Major emphasis is placed on EEG methods, particularly the need for multiple assessments to obtain estimates of asymmetric activation that better reflect an individual's true score. Issues specific to each of the two articles are also considered. Each of the articles has more consistency with our previously published data than the authors themselves suggest. Recommendations are made for future research to resolve some of the outstanding issues.

Metabolic rate in the right amygdala predicts negative affect in depressed patients.

Abstract: The role of the amygdala in major depression was investigated. Resting regional cerebral metabolic rate (rCMRglu) was measured with [18F]fluorodeoxyglucose positron emission tomography (PET) in two samples of subjects using two different PET cameras. The samples consisted of 10 and 17 medication-free depressives and 11 and 13 controls, respectively. Using coregistration of PET and magnetic resonance images, regions were individually delineated for the amygdala and thalamus, the latter of which was used as a control region. Within the depressed groups, right amygdalar rCMRglu was positively correlated with negative affect. Thalamic rCMRglu was not related to negative affect, and amygdalar rCMRglu accounted for a significant portion of variance in depressives' negative affect scores over and above the contribution of thalamic rCMRglu.

Asymmetric frontal brain activity, cortisol, and behavior associated with fearful temperament in rhesus monkeys.

Abstract: The authors examined the hypothesis that rhesus monkeys with extreme fight frontal electroencephalographic activity would have higher cortisol levels and would be more fearful compared with monkeys with extreme left frontal activity. The authors first showed that individual differences in asymmetric frontal electrical activity are a stable characteristic. Next, the authors demonstrated that relative fight asymmetric frontal activity and cortisol levels are correlated in animals 1 year of age. Additionally, extreme fight frontal animals had elevated cortisol concentrations and more intense defensive responses. At 3 years of age, extreme fight frontal animals continued to have elevated cortisol concentrations. These findings demonstrate important relations among extreme asymmetric frontal electrical activity, cortisol levels, and trait-like fear-related behaviors in young rhesus monkeys. Considerable evidence demonstrates that individual differences in temperament are associated with differences in brain and peripheral physiological functioning (e.g., Davidson & Tomarken, 1989; Kagan, Reznick, & Snidman, 1988). Thus, temperament can no longer be viewed simply as a stable trait-like behavioral and emotional style but should be considered as a constellation of stable behavioral, emotional, and physiological characteristics. How these different characteristics interact and the mechanisms underlying the formation of individual differences in temperament are important questions that remain to be answered. To begin to unravel these issues, we have used rhesus monkeys to more completely characterize the physiological concomitants of behavioral responses associated with fearful temperaments. Eventually, this information will guide studies aimed at elucidating the mechanisms underlying the development of individual differences in fear-related temperaments.

Individual differences in freezing and cortisol in infant and mother rhesus monkeys.

Abstract: Freezing is an adaptive defensive behavior that is expressed in response to an imminent threat. In prior studies with rhesus monkeys, stable individual differences in animals' propensities to freeze have been demonstrated. To understand the factors associated with these individual differences, freezing behavior was examined in infant rhesus monkeys and their mothers, in conjunction with levels of the stress-related hormone cortisol. In both mothers and infants, basal cortisol levels were positively correlated with freezing duration. Additionally, the number of offspring a mother had was negatively correlated with her infant's cortisol level. These findings suggest a link between basal cortisol levels and an animal's propensity to freeze, as well as a mechanism by which maternal experience may affect infants' cortisol levels.

Relations between PET-derived measures of thalamic glucose metabolism and EEG alpha power

Abstract: Electroencephalogram (EEG) alpha power has been demonstrated to be inversely related to mental activity and has subsequently been used as an indirect measure of brain activation. The thalamus has been proposed as an important site for modulation of rhythmic alpha activity. Studies in animals have suggested that cortical alpha rhythms are correlated with alpha rhythms in the thalamus. However, little empirical evidence exists for this relation in humans. In the current study, resting EEG and a fluorodeoxyglucose positron emission tomography scan were measured during the same experimental session. Over a 30-min period, average EEG alpha power across 28 electrodes from 27 participants was robustly inversely correlated with glucose metabolic activity in the thalamus. These data provide the first evidence for a relation between alpha EEG power and thalamic activity in humans.

Psychophysiology: The Mind–Body Perspective . By Kenneth Hugdahl. Cambridge: Harvard University Press, 1995, 429 pp.

Abstract: This volume is a very welcome addition to the relatively limited set of texts for students of psychophysiology. Kenneth Hugdahl is an exceptionally broad psychophysiologist who has used all of the major response systems in his own research and has also made important contributions to experimental and clinical neuropsychology. He is therefore well-equipped to produce a particularly distinctive text in this area and he has delivered on the promise.

Introduction to the Special Issue on Perspectives on Affective and Anxiety Disorders

Abstract: (1998). Introduction to the Special Issue on Perspectives on Affective and Anxiety Disorders. Cognition and Emotion: Vol. 12, No. 3, pp. 273-275.