Skip to main content Skip to search
Details
Displaying 26 - 50 of 222

Pages

  • Page
  • of 9
BACKGROUND: Studies using electroencephalogram (EEG) measures of activation asymmetry have reported differences in anterior asymmetry between depressed and nondepressed subjects. Several studies have suggested reciprocal relations between measures of anterior and posterior activation asymmetries. We hypothesized that depressed subjects would fail to show the normal activation of posterior right hemisphere regions in response to an appropriate cognitive challenge. METHODS: EEG activity was recorded from 11 depressed and 19 nondepressed subjects during the performance of psychometrically matched verbal (word finding) and spatial (dot localization) tasks. Band power was extracted from all epochs of artifact-free data and averaged within each condition. Task performance was also assessed. RESULTS: Depressed subjects showed a specific deficit in the performance of the spatial task, whereas no group differences were evident on verbal performance. In posterior scalp regions, nondepressed controls had a pattern of relative left-sided activation during the verbal task and relative right-sided activation during the spatial task. In contrast, depressed subjects failed to show activation in posterior right hemisphere regions during spatial task performance. CONCLUSIONS: These findings suggest that deficits in right posterior functioning underlie the observed impairments in spatial functioning among depressed subjects.
Zotero Collections:

BACKGROUND: The frontal lobe has been crucially involved in the neurobiology of major depression, but inconsistencies among studies exist, in part due to a failure of considering modulatory variables such as symptom severity, comorbidity with anxiety, and distinct subtypes, as codeterminants for patterns of brain activation in depression. METHODS: Resting electroencephalogram was recorded in 38 unmedicated subjects with major depressive disorder and 18 normal comparison subjects, and analyzed with a tomographic source localization method that computes the cortical three-dimensional distribution of current density for standard electroencephalogram frequency bands. Symptom severity and anxiety were measured via self-report and melancholic features via clinical interview. RESULTS: Depressed subjects showed more excitatory (beta3, 21.5-30.0 Hz) activity in the right superior and inferior frontal lobe (Brodmann's area 9/10/11) than comparison subjects. In melancholic subjects, this effect was particularly pronounced for severe depression, and right frontal activity correlated positively with anxiety. Depressed subjects showed posterior cingulate and precuneus hypoactivity. CONCLUSIONS: While confirming prior results implicating right frontal and posterior cingulate regions, this study highlights the importance of depression severity, anxiety, and melancholic features in patterns of brain activity accompanying depression.
Zotero Collections:

Fragile X syndrome (FXS) is the most commonly known genetic disorder associated with autism spectrum disorder (ASD). Overlapping features in these populations include gaze aversion, communication deficits, and social withdrawal. Although the association between FXS and ASD has been well documented at the behavioral level, the underlying neural mechanisms associated with the social/emotional deficits in these groups remain unclear. We collected functional brain images and eye-gaze fixations from 9 individuals with FXS and 14 individuals with idiopathic ASD, as well as 15 typically developing (TD) individuals, while they performed a facial-emotion discrimination task. The FXS group showed a similar yet less aberrant pattern of gaze fixations compared with the ASD group. The FXS group also showed fusiform gyrus (FG) hypoactivation compared with the TD control group. Activation in FG was strongly and positively associated with average eye fixation and negatively associated with ASD characteristics in the FXS group. The FXS group displayed significantly greater activation than both the TD control and ASD groups in the left hippocampus (HIPP), left superior temporal gyrus (STG), right insula (INS), and left postcentral gyrus (PCG). These group differences in brain activation are important as they suggest unique underlying face-processing neural circuitry in FXS versus idiopathic ASD, largely supporting the hypothesis that ASD characteristics in FXS and idiopathic ASD reflect partially divergent impairments at the neural level, at least in FXS individuals without a co-morbid diagnosis of ASD.
Zotero Collections:

The experience of aversion is shaped by multiple physiological and psychological factors including one's expectations. Recent work has shown that expectancy manipulation can alter perceptions of aversive events and concomitant brain activation. Accruing evidence indicates a primary role of altered expectancies in the placebo effect. Here, we probed the mechanism by which expectation attenuates sensory taste transmission by examining how brain areas activated by misleading information during an expectancy period modulate insula and amygdala activation to a highly aversive bitter taste. In a rapid event-related fMRI design, we showed that activations in the rostral anterior cingulate cortex (rACC), orbitofrontal cortex (OFC), and dorsolateral prefrontal cortex to a misleading cue that the taste would be mildly aversive predicted decreases in insula and amygdala activation to the highly aversive taste. OFC and rACC activation to the misleading cue were also associated with less aversive ratings of that taste. Additional analyses revealed consistent results demonstrating functional connectivity among the OFC, rACC, and insula. Altering expectancies of upcoming aversive events are shown here to depend on robust functional associations among brain regions implicated in prior work on the placebo effect.
Zotero Collections:

The anterior medial prefrontal (AMPFC) and retrosplenial (RSC) cortices are active during self-referential decision-making tasks such as when participants appraise traits and abilities, or current affect. Other appraisal tasks requiring an evaluative decision or mental representation, such as theory of mind and perspective-taking tasks, also involve these regions. In many instances, these types of decisions involve a subjective opinion or preference, but also a degree of ambiguity in the decision, rather than a strictly veridical response. However, this ambiguity is generally not controlled for in studies that examine self-referential decision-making. In this functional magnetic resonance imaging experiment with 17 healthy adults, we examined neural processes associated with subjective decision-making with and without an overt self-referential component. The task required subjective decisions about colors-regarding self-preference (internal subjective decision) or color similarity (external subjective decision) under conditions where there was no objectively correct response. Results indicated greater activation in the AMPFC, RSC, and caudate nucleus during internal subjective decision-making. The findings suggest that self-referential processing, rather than subjective judgments among ambiguous response alternatives, accounted for the AMPFC and RSC response.
Zotero Collections:

This study aims at investigating changes in heart rate variability (HRV) measured during meditation. The statistical and spectral measures of HRV from the RR intervals were analyzed. Results indicate that meditation may have different effects on health depending on frequency of the resonant peak that each meditator can achieve. The possible effects may concern resetting baroreflex sensitivity, increasing the parasympathetic tone, and improving efficiency of gas exchange in the lung.
Zotero Collections:

Chaotic conditions are a prevalent and threatening feature of social life. Five studies examined whether social class underlies divergent responses to perceptions of chaos in one's social environments and outcomes. The authors hypothesized that when coping with perceptions of chaos, lower class individuals tend to prioritize community, relative to upper class individuals, who instead tend to prioritize material wealth. Consistent with these predictions, when personally confronting chaos, lower class individuals were more communally oriented (Study 1), more connected with their community (Study 2), and more likely to volunteer for a community-building project (Study 3), compared to upper class individuals. In contrast, perceptions of chaos caused upper class individuals to express greater reliance on wealth (Study 4) and prefer financial gain over membership in a close-knit community (Study 5), relative to lower class individuals. These findings suggest that social class shapes how people respond to perceptions of chaos and cope with its threatening consequences.
Zotero Collections:

The authors examined the time course of affective responding associated with different affective dimensions--anxious apprehension, anxious arousal, and anhedonic depression--using an emotion-modulated startle paradigm. Participants high on 1 of these 3 dimensions and nonsymptomatic control participants viewed a series of affective pictures with acoustic startle probes presented before, during, and after the stimuli. All groups exhibited startle potentiation during unpleasant pictures and in anticipation of both pleasant and unpleasant pictures. Compared with control participants, symptomatic participants exhibited sustained potentiation following the offset of unpleasant stimuli and a lack of blink attenuation during and following pleasant stimuli. Common and unique patterns of affective responses in the 3 types of mood symptoms are discussed.
Zotero Collections:

Functional neuroimaging research has demonstrated that retrieving information about object-associated colors activates the left fusiform gyrus in posterior temporal cortex. Although regions near the fusiform have previously been implicated in color perception, it remains unclear whether color knowledge retrieval actually activates the color perception system. Evidence to this effect would be particularly strong if color perception cortex was activated by color knowledge retrieval triggered strictly with linguistic stimuli. To address this question, subjects performed two tasks while undergoing fMRI. First, subjects performed a property verification task using only words to assess conceptual knowledge. On each trial, subjects verified whether a named color or motor property was true of a named object (e.g., TAXI-yellow, HAIR-combed). Next, subjects performed a color perception task. A region of the left fusiform gyrus that was highly responsive during color perception also showed greater activity for retrieving color than motor property knowledge. These data provide the first evidence for a direct overlap in the neural bases of color perception and stored information about object-associated color, and they significantly add to accumulating evidence that conceptual knowledge is grounded in the brain's modality-specific systems.
Zotero Collections:

The study of emotional communication has focused predominantly on the facial and vocal channels but has ignored the tactile channel. Participants in the current study were allowed to touch an unacquainted partner on the whole body to communicate distinct emotions. Of interest was how accurately the person being touched decoded the intended emotions without seeing the tactile stimulation. The data indicated that anger, fear, disgust, love, gratitude, and sympathy were decoded at greater than chance levels, as well as happiness and sadness, 2 emotions that have not been shown to be communicated by touch to date. Moreover, fine-grained coding documented specific touch behaviors associated with different emotions. The findings are discussed in terms of their contribution to the study of emotion-related communication.
Zotero Collections:

Psychological stress is a major provocative factor of symptoms in chronic inflammatory conditions. In recent years, interest in addressing stress responsivity through meditation training in health-related domains has increased astoundingly, despite a paucity of evidence that reported benefits are specific to meditation practice. We designed the present study to rigorously compare an 8-week Mindfulness-Based Stress Reduction (MBSR) intervention to a well-matched active control intervention, the Health Enhancement Program (HEP) in ability to reduce psychological stress and experimentally-induced inflammation. The Trier Social Stress Test (TSST) was used to induce psychological stress and inflammation was produced using topical application of capsaicin cream to forearm skin. Immune and endocrine measures of inflammation and stress were collected both before and after MBSR training. Results show those randomized to MBSR and HEP training had comparable post-training stress-evoked cortisol responses, as well as equivalent reductions in self-reported psychological distress and physical symptoms. However, MBSR training resulted in a significantly smaller post-stress inflammatory response compared to HEP, despite equivalent levels of stress hormones. These results suggest behavioral interventions designed to reduce emotional reactivity may be of therapeutic benefit in chronic inflammatory conditions. Moreover, mindfulness practice, in particular, may be more efficacious in symptom relief than the well-being promoting activities cultivated in the HEP program.

Psychological stress is a major provocative factor of symptoms in chronic inflammatory conditions. In recent years, interest in addressing stress responsivity through meditation training in health-related domains has increased astoundingly, despite a paucity of evidence that reported benefits are specific to meditation practice. We designed the present study to rigorously compare an 8-week Mindfulness-Based Stress Reduction (MBSR) intervention to a well-matched active control intervention, the Health Enhancement Program (HEP) in ability to reduce psychological stress and experimentally-induced inflammation. The Trier Social Stress Test (TSST) was used to induce psychological stress and inflammation was produced using topical application of capsaicin cream to forearm skin. Immune and endocrine measures of inflammation and stress were collected both before and after MBSR training. Results show those randomized to MBSR and HEP training had comparable post-training stress-evoked cortisol responses, as well as equivalent reductions in self-reported psychological distress and physical symptoms. However, MBSR training resulted in a significantly smaller post-stress inflammatory response compared to HEP, despite equivalent levels of stress hormones. These results suggest behavioral interventions designed to reduce emotional reactivity may be of therapeutic benefit in chronic inflammatory conditions. Moreover, mindfulness practice, in particular, may be more efficacious in symptom relief than the well-being promoting activities cultivated in the HEP program.
Zotero Collections:

What is compassion? And how did it evolve? In this review, we integrate 3 evolutionary arguments that converge on the hypothesis that compassion evolved as a distinct affective experience whose primary function is to facilitate cooperation and protection of the weak and those who suffer. Our empirical review reveals compassion to have distinct appraisal processes attuned to undeserved suffering; distinct signaling behavior related to caregiving patterns of touch, posture, and vocalization; and a phenomenological experience and physiological response that orients the individual to social approach. This response profile of compassion differs from those of distress, sadness, and love, suggesting that compassion is indeed a distinct emotion. We conclude by considering how compassion shapes moral judgment and action, how it varies across different cultures, and how it may engage specific patterns of neural activation, as well as emerging directions of research.
Zotero Collections:

Three experiments were performed testing the effects of a variety of impedance cardiograph electrode types and recording arrangements on recorded electroencephalography (EEG) using either a monopolar single-ear reference or a physically linked ears reference. EEG was recorded either alone or concurrently with an impedance cardiograph. When the cardiograph was recorded using a spot electrode for the top current-inducing electrode, there was an overall decrease in power density of the EEG, and this effect was dependent on the location of the recording electrode. This effect was diminished when the top cardiograph spot electrode was replaced by a mylar-coated neck band electrode and EEG was recorded using a monopolar, single-ear reference. However, there tended to be an overall increase in log power density of the EEG in each frequency band below 60 Hz when less technologically advanced EEG amplifiers were used. This effect was diminished if the EEG was recorded using a physically linked ears reference. Recommendations for the concurrent recording of EEG and impedance cardiography are discussed.
Zotero Collections:

Greater levels of conscientiousness have been associated with lower levels of negative affect. We focus on one mechanism through which conscientiousness may decrease negative affect: effective emotion regulation, as reflected by greater recovery from negative stimuli. In 273 adults who were 35-85 years old, we collected self-report measures of personality including conscientiousness and its self-control facet, followed on average 2 years later by psychophysiological measures of emotional reactivity and recovery. Among middle-aged adults (35-65 years old), the measures of conscientiousness and self-control predicted greater recovery from, but not reactivity to, negative emotional stimuli. The effect of conscientiousness and self-control on recovery was not driven by other personality variables or by greater task adherence on the part of high conscientiousness individuals. In addition, the effect was specific to negative emotional stimuli and did not hold for neutral or positive emotional stimuli.
Zotero Collections:

Purpose Although quantitative benefits of mindfulness training have been demonstrated in youth, little is known about the processes involved. The aim of this study was to gain a detailed understanding of how young people engage with the ideas and practices known as mindfulness using qualitative enquiry. Methods Following completion of a six-week mindfulness training program with a nonclinical group of 11 young people (age 16–24), a focus group (N = 7) and open-ended interviews (n = 5) were held and audio-recorded. Qualitative data, collected at eight time points over three months from the commencement of training, were coded with the aid of computer software. Grounded theory methodology informed the data collection process and generation of themes and an explanatory model that captured participants' experiences. Results Participants described their daily lives as beset by frequent experiences of distress sometimes worsened by their unhelpful or destructive reactions. With mindfulness practice, they initially reported greater calm, balance, and control. Subsequently they commented on a clearer understanding of themselves and others. Mindfulness was then described as a “mindset” associated with greater confidence and competence and a lessened risk of future distress. Conclusions Participants demonstrated a sophisticated understanding of and engagement with mindfulness principles and practice. Their reported experience aligned well with qualitative research findings in adults and theoretical literature on mindfulness. An encouraging finding was that, with ongoing mindfulness practice and within a relatively short time, participants were able to move beyond improved emotion regulation and gain greater confidence in their ability to manage life challenges.
Zotero Collections:

Concepts develop for many aspects of experience, including abstract internal states and abstract social activities that do not refer to concrete entities in the world. The current study assessed the hypothesis that, like concrete concepts, distributed neural patterns of relevant nonlinguistic semantic content represent the meanings of abstract concepts. In a novel neuroimaging paradigm, participants processed two abstract concepts (convince, arithmetic) and two concrete concepts (rolling, red) deeply and repeatedly during a concept-scene matching task that grounded each concept in typical contexts. Using a catch trial design, neural activity associated with each concept word was separated from neural activity associated with subsequent visual scenes to assess activations underlying the detailed semantics of each concept. We predicted that brain regions underlying mentalizing and social cognition (e.g., medial prefrontal cortex, superior temporal sulcus) would become active to represent semantic content central to convince, whereas brain regions underlying numerical cognition (e.g., bilateral intraparietal sulcus) would become active to represent semantic content central to arithmetic. The results supported these predictions, suggesting that the meanings of abstract concepts arise from distributed neural systems that represent concept-specific content.
Zotero Collections:

Poor sleep is common in substance use disorders (SUDs) and is a risk factor for relapse. Within the context of a multicomponent, mindfulness-based sleep intervention that included mindfulness meditation (MM) for adolescent outpatients with SUDs (n = 55), this analysis assessed the contributions of MM practice intensity to gains in sleep quality and self-efficacy related to SUDs. Eighteen adolescents completed a 6-session study intervention and questionnaires on psychological distress, sleep quality, mindfulness practice, and substance use at baseline, 8, 20, and 60 weeks postentry. Program participation was associated with improvements in sleep and emotional distress, and reduced substance use. MM practice frequency correlated with increased sleep duration and improvement in self-efficacy about substance use. Increased sleep duration was associated with improvements in psychological distress, relapse resistance, and substance use-related problems. These findings suggest that sleep is an important therapeutic target in substance abusing adolescents and that MM may be a useful component to promote improved sleep.

Poor sleep is common in substance use disorders (SUDs) and is a risk factor for relapse. Within the context of a multicomponent, mindfulness-based sleep intervention that included mindfulness meditation (MM) for adolescent outpatients with SUDs (n = 55), this analysis assessed the contributions of MM practice intensity to gains in sleep quality and self-efficacy related to SUDs. Eighteen adolescents completed a 6-session study intervention and questionnaires on psychological distress, sleep quality, mindfulness practice, and substance use at baseline, 8, 20, and 60 weeks postentry. Program participation was associated with improvements in sleep and emotional distress, and reduced substance use. MM practice frequency correlated with increased sleep duration and improvement in self-efficacy about substance use. Increased sleep duration was associated with improvements in psychological distress, relapse resistance, and substance use-related problems. These findings suggest that sleep is an important therapeutic target in substance abusing adolescents and that MM may be a useful component to promote improved sleep.
Zotero Collections:

We present a novel data smoothing and analysis framework for cortical thickness data defined on the brain cortical manifold. Gaussian kernel smoothing, which weights neighboring observations according to their 3D Euclidean distance, has been widely used in 3D brain images to increase the signal-to-noise ratio. When the observations lie on a convoluted brain surface, however, it is more natural to assign the weights based on the geodesic distance along the surface. We therefore develop a framework for geodesic distance-based kernel smoothing and statistical analysis on the cortical manifolds. As an illustration, we apply our methods in detecting the regions of abnormal cortical thickness in 16 high functioning autistic children via random field based multiple comparison correction that utilizes the new smoothing technique.
Zotero Collections:

Many investigators have hypothesized that brain response to cortisol is altered in depression. However, neural activation in response to exogenously manipulated cortisol elevations has not yet been directly examined in depressed humans. Animal research shows that glucocorticoids have robust effects on hippocampal function, and can either enhance or suppress neuroplastic events in the hippocampus depending on a number of factors. We hypothesized that depressed individuals would show 1) altered hippocampal response to exogenous administration of cortisol, and 2) altered effects of cortisol on learning. In a repeated-measures design, 19 unmedicated depressed and 41 healthy individuals completed two fMRI scans. Fifteen mg oral hydrocortisone (i.e., cortisol) or placebo (order randomized and double-blind) was administered 1 h prior to encoding of emotional and neutral words during fMRI scans. Data analysis examined the effects of cortisol administration on 1) brain activation during encoding, and 2) subsequent free recall for words. Cortisol affected subsequent recall performance in depressed but not healthy individuals. We found alterations in hippocampal response to cortisol in depressed women, but not in depressed men (who showed altered response to cortisol in other regions, including subgenual prefrontal cortex). In both depressed men and women, cortisol's effects on hippocampal function were positively correlated with its effects on recall performance assessed days later. Our data provide evidence that in depressed compared to healthy women, cortisol's effects on hippocampal function are altered. Our data also show that in both depressed men and women, cortisol's effects on emotional memory formation and hippocampal function are related.
Zotero Collections:

In a test of the effects of cortisol on emotional memory, 90 men were orally administered placebo or 20 or 40 mg cortisol and presented with emotionally arousing and neutral stimuli. On memory tests administered within 1 hr of stimulus presentation, cortisol elevations caused a reduction in the number of errors committed on free-recall tasks. Two evenings later, when cortisol levels were no longer manipulated, inverted-U quadratic trends were found for recognition memory tasks, reflecting memory facilitation in the 20-mg group for both negative and neutral information. Results suggest that the effects of cortisol on memory do not differ substantially for emotional and neutral information. The study provides evidence of beneficial effects of acute cortisol elevations on explicit memory in humans.
Zotero Collections:

In rodents, theta rhythm has been linked to the hippocampal formation, as well as other regions, including the anterior cingulate cortex (ACC). To test the role of the ACC in theta rhythm, concurrent measurements of brain electrical activity (EEG) and glucose metabolism (PET) were performed in 29 subjects at baseline. EEG data were analyzed with a source localization technique that enabled voxelwise correlations of EEG and PET data. For theta, but not other bands, the rostral ACC (Brodmann areas 24/32) was the largest cluster with positive correlations between current density and glucose metabolism. Positive correlations were also found in right fronto-temporal regions. In control but not depressed subjects, theta within ACC and prefrontal/orbitofrontal regions was positively correlated. The results reveal a link between theta and cerebral metabolism in the ACC as well as disruption of functional connectivity within frontocingulate pathways in depression.
Zotero Collections:

This study was designed to test the hypothesis that Japanese subjects exhibit different patterns of resting EEG asymmetry compared with Westerners. EEG was recorded from the left and right temporal and parietal scalp regions in bilingual Japanese and Western subjects during eyes-open and eyes-closed rest periods before and after the performance of a series of cognitive tasks. Alpha activity was integrated and digitized. Japanese subjects were found to exhibit greater relative right-sided parietal activation during the eyes closed condition. This difference was found to be a function of greater left hemisphere activation among the Westerners. Various possible contributors to this cross-cultural differences are discussed.
Zotero Collections:

Pages

  • Page
  • of 9