Biomedical subjects

Estibaliz Arce

Publications and source records attributed to Estibaliz Arce.

5 recordsLinked to original sources

PubMed2006

Lorazepam dose-dependently decreases risk-taking related activation in limbic areas.

RATIONALE: Several studies have examined the role of different neurotransmitter systems in modulating risk-taking behavior. OBJECTIVE: This investigation was aimed to determine whether the benzodiazepine lorazepam dose-dependently alters risk-taking behavior and underlying neural substrates. MATERIALS AND METHODS: Fifteen healthy, nonsmoking, individuals (six women, nine men), aged 18-39 years (mean 27.6 +/- 1.4 years) with 12-18 years of education (mean 15.6 +/- 0.3 years) underwent functional magnetic resonance imaging while performing a risk-taking decision-making task. RESULTS: Our results show that lorazepam did not affect risky behavior at 0.25 and 1 mg, but dose-dependently attenuated activation in (a) the amygdala and medial prefrontal cortex during the response selection phase, and in (b) the bilateral insular cortex and amygdala during the outcome (i.e., rewarded or punished) phase. Furthermore, a lorazepam-induced increase in insular cortex activation was associated with less risky responses. CONCLUSIONS: Taken together, our findings support the idea that GABAergic modulation in limbic and paralimbic structures is important during both the response selection and outcome phase of risk-taking decision-making.

Administration, Oral↗

PubMed2006

Young adult stimulant users' increased striatal activation during uncertainty is related to impulsivity.

BACKGROUND: Young adults who use stimulants (e.g., cocaine, amphetamines) are at particular risk of transitioning to dependence. Previously, we demonstrated increased risk-taking in young adults who had used stimulants (Leland, D.S., Paulus, M.P., 2005. Increased risk-taking decision-making but not altered response to punishment in stimulant-using young adults. Drug. Alcohol Depend. 78, 83-90). Since outcome uncertainty is a critical element of risk, we investigated whether such individuals have different neural responses to uncertainty than their stimulant-naive peers. METHOD: Eleven young adults (age 18-25) who had used stimulants were compared with 11 age- and education-matched stimulant-naive controls using functional magnetic resonance imaging and a card prediction task with relatively certain/uncertain outcome conditions. RESULTS: The caudate, an area involved in processing salient events, was among those regions more active in users than controls in response to uncertainty. Personality measures revealed that users were more impulsive than controls, and that neural response to uncertainty in a number of areas, including the thalamus/caudate, was positively correlated with impulsivity. CONCLUSIONS: These results are consistent with the idea that young adults who have used stimulants find uncertainty particularly salient, due in part to preexisting differences in impulsivity, and may be subject to more "action pressure" when making decisions under uncertainty. This neural and personality profile may constitute a marker for increased risk of stimulant use.

Adult↗

PubMed2006

Individuals with schizophrenia present hypo- and hyperactivation during implicit cueing in an inhibitory task.

BACKGROUND: The primary purpose of this investigation was to assess the neural correlates of implicit cueing during an inhibitory task in schizophrenia when performance accuracy was matched with healthy comparison subjects. METHODS: We compared 17 individuals with chronic schizophrenia (SZ; medicated, 13.9 average years of illness) and 17 healthy comparison subjects (HC) matched for hit and false alarm rates, age, and education on a visual Go/Nogo task during functional magnetic resonance imaging. In this task, one of the go stimuli also served implicitly as a cue predictive of a subsequent inhibitory (Nogo) trial. CONCLUSIONS: Findings suggest that even when matched for overall performance accuracy, individuals with SZ exhibit difficulties with inhibition and cue processing that may relate to core deficits in cognitive control and stimulus processing. In particular, these findings point towards an important role of the parietal cortex for cued inhibitory processes in healthy populations.

Adult↗

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↗

PubMed2004

Hippocampal structural asymmetry in unsuccessful psychopaths.

BACKGROUND: Structural and functional hippocampal abnormalities have been previously reported in institutionalized psychopathic and aggressive populations. This study assessed whether prior findings of a right greater than left (R > L) functional asymmetry in caught violent offenders generalize to the structural domain in unsuccessful, caught psychopaths. METHODS: Left and right hippocampal volumes were assessed using structural magnetic resonance imaging (MRI) in 23 control subjects, 16 unsuccessful psychopaths, and 12 successful (uncaught) community psychopaths and transformed into standardized space. RESULTS: Unsuccessful psychopaths showed an exaggerated structural hippocampal asymmetry (R > L) relative both to successful psychopaths and control subjects (p <.007) that was localized to the anterior region. This effect could not be explained by environmental and diagnostic confounds and constitutes the first brain imaging analysis of successful and unsuccessful psychopaths. CONCLUSIONS: Atypical anterior hippocampal asymmetries in unsuccessful psychopaths may reflect an underlying neurodevelopmental abnormality that disrupts hippocampal-prefrontal circuitry, resulting in affect dysregulation, poor contextual fear conditioning, and insensitivity to cues predicting capture.

Adult↗