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Biomedical subjects

Scott C Matthews

Publications and source records attributed to Scott C Matthews.

15 recordsLinked to original sources
PubMed2006

Anticipation of aversive visual stimuli is associated with increased insula activation in anxiety-prone subjects.

BACKGROUND: Anticipation is a critical component of affective processing in general and for anxiety in particular. Prior research suggests that the right insula plays an important role in anticipation of affective processing during aversive images. This study aimed to test the hypothesis that individuals with increased anxiety-related temperamental traits (anxiety-prone [AP]) relative to anxiety-normative (AN) subjects would show an exaggerated insula response during anticipation of an aversive image. METHODS: 16 AP and 16 AN individuals performed a task in the functional magnetic resonance imaging scanner, during which they viewed pictures of spiders and snakes. Subjects were prompted 4-6 sec before the onset of each aversive image. Blood oxygenation level-dependent signal was contrasted during cued anticipation of images versus non-anticipatory task performance as well as viewing images. RESULTS: As hypothesized, AP subjects showed greater response than AN subjects in the bilateral insula during anticipation. In addition, these individuals had lower activity within the superior/medial frontal gyrus. During the image presentation phase, AN subjects showed greater activation than AP subjects in the bilateral temporal lobes and left superior frontal gyrus. Moreover, bilateral temporal lobe activation during image presentation was inversely correlated with bilateral insula activation during anticipation both within groups and in the combined group. CONCLUSIONS: These data suggest that greater activation of the insula during visual anticipation is associated with visual processing of aversive stimuli in AP individuals. Insula hyperactivity might be a common feature in persons with elevated trait anxiety and, as such, might be a neuroimaging marker for anxiety proneness.

Adolescent↗
PubMed2005

Affective ambiguity for a group recruits ventromedial prefrontal cortex.

Affective appraisal often involves processing complex and ambiguous stimuli, such as the mood of a group people. However, affective neuroimaging research often uses individual faces as stimuli when exploring the neural circuitry involved in social appraisal. Results from studies using single face paradigms may not generalize to settings where multiple faces are simultaneously processed. The goal of the current study was to use a novel task that presents groups of affective faces to probe the medial prefrontal cortex (PFC), a region that is critically involved in appraisal of ambiguous affective stimuli, in healthy volunteers. In the current study, 27 subjects performed the Wall of Faces (WOF) task in which multiple matrices of faces were briefly presented during functional MRI. Subjects were asked to decide whether there were more angry or happy faces (emotional decision) or whether there were more male or female faces (gender decision). In each condition, the array contained either an equal (ambiguous trials) or an unequal (unambiguous trials) distribution of one affect or gender. Ambiguous trials relative to unambiguous trials activated regions implicated in conflict monitoring and cognitive control, including the dorsal anterior cingulate cortex (ACC), dorsolateral PFC, and posterior parietal cortex. When comparing ambiguous affective decisions with ambiguous gender decisions, the ventromedial PFC (including the ventral ACC) was significantly more active. This supports the dissociation of the ACC into dorsal cognitive and ventral affective divisions, and suggests that the ventromedial PFC may play a critical role in appraising affective tone in a complex display of multiple human faces.

Adolescent↗
PubMed2005

Dissociation of inhibition from error processing using a parametric inhibitory task during functional magnetic resonance imaging.

Inhibition, the process that overrides and reverses the execution of a thought, action, or emotion, is important in daily life. Sixteen healthy volunteers performed a parametrically modulated motor inhibition task during functional magnetic resonance imaging. Two results were observed: (1) increased error-related anterior cingulate cortex activation and, (2) increased inferior frontal gyrus and medial prefrontal cortex activation during inhibition, irrespective of errors. Thus, the parametric nature of the task elucidated a functional dissociation of brain structures involved in motor inhibition from those involved in error processing. Additionally, this task allowed the identification of unique areas of increased activation within specific subregions of the anterior cingulate cortex related to errors made during trials with a high (dorsal anterior cingulate cortex) and low (ventral anterior cingulate cortex) inhibitory load.

Adult↗
PubMed2005

Use of GHB compounds among college students.

There are increasing reports about the misuse of gamma hydroxybutyric acid (GHB) related compounds. The objective of this article is to examine the use of GHB-containing dietary supplements among college students. An anonymous survey was completed at a university health clinic. The survey asked participants about their experience using GHB compounds and their knowledge about the legal status of GHB and its addictive potential. Two hundred fifteen students responded to the survey. Twenty-eight percent had used GHRE and 19% had used GHB. Growth Hormone Release Extract (GHRE) users reported consumption 2-3 times per month and GHB users reported 1-2 times per month. Males tended to use GHB for euphoria and energy, while females tended to use the compounds for weight loss. GHB was particularly popular among homosexual and bisexual responders. There was little knowledge of the addictive potential and illegal status of GHB and related compounds. GHB compounds are commonly used among college students. Given the different reasons for use according to gender and sexual orientation, prevention programs need to sculpt their message according to the target audience.

Adolescent↗
PubMed2004

Attenuation of T-lymphocyte demargination and adhesion molecule expression in response to moderate exercise in physically fit individuals.

The effects of physical fitness on leukocyte demargination and cellular adhesion molecule (CAM) responses to moderate exercise were examined. We assessed leukocyte subsets and CAM expression before, immediately after, and 10 min after a 20-min treadmill exercise at 65-70% peak oxygen consumption in fit vs. nonfit individuals. Physical fitness was determined by peak oxygen consumption during a treadmill test. Catecholamine levels were determined by radioenzymatic assay, and enumeration of cells and detection of CAM expression were assessed by flow cytometry. As expected, exercise led to significant increases in numbers of leukocyte subsets, regardless of fitness level (P < 0.01). Values returned to near resting levels 10 min after exercise. More importantly, physically fit individuals showed attenuated responses to the moderate-exercise challenge in numbers of CD3(+), CD4(+), CD8(+), memory (CD45RO(+)) CD4, and naive (CD45RA(+)62L(+)) CD4 and CD8 lymphocytes. Postexercise human leukocyte antigen-DR absent memory CD4(+) cell numbers were also lower in fit subjects. Increases in CD62L-expressing CD4(+) and CD8(+) lymphocytes and CD11a- expressing lymphocytes after exercise were also attenuated in fit individuals compared with nonfit individuals (P < 0.05). Catecholamine levels increased to a similar extent (P < 0.01) in both fitness groups. The findings suggest that physical fitness attenuates demargination of selected lymphocyte subsets in response to moderate exercise. Although the differences in plasma catecholamine responses were not significant between the groups, a possible mediating role of the sympathetic system remains to be further investigated. Being physically fit may offset exaggerated immune cell responses to stress.

Adaptation, Physiological↗
PubMed2004

Anticipation of emotionally aversive visual stimuli activates right insula.

Understanding the neural substrates of anticipation is required for a comprehensive model of the ways in which anxiety influences information processing. While it is apparent that the insula and medial frontal cortex are involved in processing anticipation of physical (i.e., painful) stimuli, their role in processing anticipation of aversive affective stimuli has yet to be determined. Twenty-eight healthy non-phobic volunteers observed aversive affective images (spiders and snakes) that were preceded by an auditory signal. The insula, dorsolateral prefrontal cortex, and parahippocampal gyrus activated during anticipation of aversive affective images. These findings indicate that common neural circuitry is involved in the anticipation of (and, perhaps, the subjective experience of anticipating) aversive affective and noxious physical stimuli.

Adolescent↗
PubMed2004

Selective activation of the nucleus accumbens during risk-taking decision making.

This study implemented a risk-taking task during fMRI to probe the brain circuitry involved in risk-taking decision-making in 12 healthy control subjects. Partially supporting the initial hypotheses, deliberation prior to selection of safe relative to risky responses generated greater activation in the inferior frontal cortex, superior temporal gyrus, and middle temporal gyrus; and deliberation prior to selection of risky relative to safe responses generated greater activation in medial frontal cortex, occipital cortex, nucleus accumbens and caudate. Additionally, accumbens activation correlated positively with the harm avoidance subscale of the Temperament and Character Inventory (TCI) 125. These findings may provide target neural systems to study in subjects who exhibit problematic risk-taking behaviors and may partially explain why certain risky behaviors occur.

Adult↗
PubMed2004

Functional subdivisions within anterior cingulate cortex and their relationship to autonomic nervous system function.

The anterior cingulate cortex (ACC) has diverse functions and several functional subdivisions. This study implemented a counting Stroop task that presented incongruent (INC) and congruent (CON) stimuli at two speeds to probe dorsal (dACC) and ventral (vACC) using functional magnetic resonance imaging (fMRI). Eighteen healthy subjects completed the task twice: once outside the scanner while heart rate variability (HRV) was recorded and once during fMRI. In both sessions, subjects completed two runs. Stimuli were presented every 2.0 s in one run and every 1.5 s in the other. fMRI data analysis revealed two important findings. First, by computing differential activation between INC and CON stimuli, a cluster of activation related to response inhibition was observed in the left dACC. Additionally, by calculating the interaction of speed with stimulus congruency, a cluster of activation was observed in the left vACC. This activation correlated significantly with high-frequency HRV (P < 0.02 for CON and P < 0.003 for INC) and represents the parasympathetic modulatory role of the vACC. This study supports the notion of functional subdivisions within the ACC and links the processes of cognitive interference and parasympathetic modulation with activation in specific subregions of the ACC, a structure that is critical for the interface between cognition and emotion.

Adult↗
PubMedDate not supplied

Use of herbal medications among 200 psychiatric outpatients: prevalence, patterns of use, and potential dangers.

We documented the use rates of herbal medication among a population of psychiatric outpatients to identify patients at risk for drug-herb interactions. Data were collected on 200 patients who, as part of their routine evaluation, provided information regarding their use of herbs. Fifteen percent of patients were currently taking herbs, the majority for treatment of psychiatric symptoms. There were no significant differences in use patterns across gender or between age groups. None of the current users charts, including the "high risk" patients, indicated that treating physicians were aware of potentially dangerous drug-herb combinations. Use of herbal medication was common among this sample of psychiatric outpatients. These data are consistent with reports from other patient populations. It is important for psychiatrists to ask all patients about their use of herbs and provide education about potentially dangerous drug-herb interactions.

Adult↗
PubMedDate not supplied

Use of GHB compounds by HIV-positive individuals.

Gamma hydroxybutyrate (GHB) has been used by body-builders to enhance performance and by young adults in rave parties. Warnings have been posted about its addictive potential. The use of these dietary compounds is currently banned by the Food and Drug Administration, but they are widely available through the Internet and in certain communities. The purpose of the study was to examine the use of these compounds by HIV-positive individuals and to investigate their knowledge of the addictive potential of GHB and its related dietary compounds. One hundred HIV-positive individuals from the UCSD outpatient HIV clinic responded to an anonymous survey that inquired about their knowledge, use, and effects produced by GHB containing dietary compounds. The most common reported dietary compound beside GHB was Growth Hormone Release Extract (GHRE). Fifty-two percent of individuals reported using at least one GHB containing dietary compound. Gay subjects reported the highest use of GHB compounds (76.9%; p < or = 0.001). The most common effect reported by users was increased energy (71%). Only 24% of the total responders knew about GHB's addictive potential. Among reported users of GHB containing compounds, fourteen (27%) knew about its addictive potential and nine (17%) knew that the compound is illegal. This study shows that HIV-positive gay individuals attending our clinic are using GHB compounds. Reported GHB users have limited knowledge about its addictive potential and serious adverse effects. More controlled studies are needed to evaluate long-term effects of dietary compounds containing GHB, especially among HIV-positive individuals who are actively receiving antiretroviral treatment.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Depressive symptoms are associated with increased systemic vascular resistance to stress.

OBJECTIVE: The deleterious effects of major depressive disorder on cardiovascular (CV) functioning are well known. However, the etiologic mechanisms underlying this association are incompletely understood. In the current study, subjects with varying degrees of depressive symptoms performed a stress task while CV reactivity was measured. We hypothesized that high levels of depressive symptoms would be associated with altered CV reactivity. METHODS: Ninety-one healthy volunteer subjects performed reactivity testing while measures of impedance cardiography and autonomic nervous system function were obtained. Subjects completed the Center for Epidemiological Studies Depression Scale (CES-D) and were categorized into either the high depressive (i.e., CES-D > or =16) or low depressive (i.e., CES-D <16) symptoms group. RESULTS: Task performance was associated with increases in systemic vascular resistance (SVR) (p = .001), mean arterial pressure (p = .001), and heart rate (p = .005), and decreases in cardiac output (p = .001), heather index (p = .001), and stroke volume (p = .05). After controlling for screening mean arterial pressure, an interaction effect of stress by mood group on SVR (p = .01) was observed; subjects with high amounts of depressive symptoms manifested significantly greater SVR at baseline and in response to a stressor task than did subjects with low amounts of depressive symptoms. CONCLUSIONS: These results suggest a mechanism that may partially explain the increased CV morbidity associated with depressive symptoms. In future studies, it may be useful to examine if treatment of depressive symptoms alters CV reactivity.

Adult↗
PubMedDate not supplied

The internet for medical information about cancer: help or hindrance?

OBJECTIVE: The authors tested a strategy for screening Internet sites to identify those that provide scientifically accurate information regarding complementary/alternative medicine treatments commonly used by cancer patients. METHOD: Separate Internet searches were conducted for three complementary/alternative medicine treatments: floressence, amalaki, and selenium. Sites (N=194) were assessed according to four criteria: availability of online purchasing, inclusion of patient testimonials, description of the treatment as a "cancer cure," and description of the treatment as "having no side effects." The presence of any of these criteria was considered a "red flag" denoting questionable scientific accuracy of the site. Sites were categorized based on the number of red flags. MEDLINE searches were performed and peer-reviewed literature used to determine the scientific accuracy of sites. RESULTS: Over 90% of the sites for floressence and amalaki had at least one red flag. In these searches, sites with no red flags provided some scientifically accurate information, while sites with red flags provided a large amount of vague and inaccurate information. Less than one-quarter of sites for selenium had at least one red flag, and sites in this search generally provided scientifically accurate information, regardless of the number of red flags. CONCLUSIONS: There is a staggering amount of medical misinformation on the Internet. For cancer treatments that have not been rigorously studied, the red flag criteria offer a rapid way of screening Internet sites for likely scientific accuracy. It may be advisable for patients to avoid sites with one or more red flags.

Humans↗
PubMedDate not supplied

Contribution of functional neuroimaging to understanding neuropsychiatric side effects of interferon in hepatitis C.

Patients with hepatitis C who are treated with interferon may develop neuropsychiatric symptoms, including fatigue and depression. The authors discuss the potential use of functional neuroimaging in the identification and treatment of these patients. The authors provide an overview of functional neuroimaging studies of fatigue and depressive symptoms in various medical and psychiatric conditions and suggest future directions for research that may increase understanding of the specific neural substrates of neuropsychiatric side effects associated with hepatitis C and interferon treatment. This knowledge may help consultation-liaison psychiatrists identify patients at high risk for developing side effects related to hepatitis C and interferon, which would allow for implementation of validated strategies for prophylactic treatment of these patients.

Antineoplastic Agents↗
PubMedDate not supplied

Ethnicity and use of alternative products in psychiatric patients.

The use of herbal and natural products for medical purposes is common in all human civilizations, and use in Western societies has grown considerably in recent years. However, differences in usage patterns between different ethnic groups are yet to be delineated. The current study examined the frequency and type of complementary/alternative medications used by a sample of 453 rural psychiatric outpatients of two different ethnic groups. The products were classified as "natural" (herbal products requiring some preparation before consumption) and "processed" (products in "ready-to-use" form). There were significant ethnic differences in usage patterns of the various preparations: Hispanics, relative to Caucasians, were twice as likely to use natural products, whereas Caucasians were more likely than Hispanics to use processed products. The symptoms addressed were predominantly psychiatric, with natural products, and nonpsychiatric, with processed products. These results may increase awareness among healthcare providers regarding the usage frequency of such complementary/alternative medications products and the different usage patterns across ethnic groups.

California↗