Orbitofrontal cortex and dynamic filtering of emotional stimuli

Event-related potentials (ER) were recorded in response to mildly aversive somatosensory and auditory stimuli. Patients with orbitofrontal lesions exhited enhanced ERPs (i.e., P3 amplitudes), as compared with control subjects. Moreover, these patients did not habituate to somatoensory stimuli across blocks of trials. The results were specific to orbitofrontal damage, since patients with damage to the dorsolateral prefontal cortex did not exhibit enhanced P3 amplitudes. These findings suggest damage to the orbitofrontal cortex impairs the ability to modulate or inhibit neural responses to aversive stimuli. The findings are couched in terms of dynamic filtering theory, which suggests that the orbitofrontal cortex is involved in the selection and active inhibition of neural circuits associated with emotional responses.     

Affective and cognitive modulation of performance monitoring: Behavioral and ERP evidence

This study investigates the effects of negative affect on performance monitoring. EEG was acquired during a lateralized, numeric Stroop working memory task that featured task-irrelevant aversive and neutral pictures between stimuli. Performance accuracy showed a right-hemisphere advantage for stimuli that followed aversive pictures. Response-locked event-related potentials (ERPs) from accurate trials showed an early negative component (CRN; correct response/conflict-related negativity) followed by a positive wave comparable to the Pe (error positivity). The CRN was bi-peaked with an earlier peak that was sensitive to aversive pictures during early portions of the experiment and a later peak that increased with error likelihood later in the experiment. Pe amplitude was increased with aversive pictures early in the experiment and was sensitive to picture type, Stroop interference, and hemisphere of stimulus delivery during later trials. This suggests that ERP indices of performance monitoring, the CRN and Pe, are dynamically modulated by both affective and cognitive demands.     

A process-oriented approach for averting confounds resulting from general performance deficiencies in schizophrenia

The most pervasive and least well-addressed problem in cognitive studies of schizophrenia is the propensity of schizophrenia patients to show inferior performance on a variety of cognitive tasks. Consequently, apparent specific cognitive abnormalities may actually reflect the interaction of task discriminating power with generalized deficit. L. J. Chapman and J. P. Chapman (1973a) suggested psychometric approaches for eliminating such artifactual group differences. Unfortunately, their solution neglects important issues of process specification and does not provide a viable strategy for process-oriented investigators. Psychometric remediation of artifactual Group x Task interactions inevitably confounds the processes being measured, resulting in theoretically ambiguous findings. Moreover, evidence that changes in measurement reliability can both increase and decrease group discrimination challenges a basic underlying assumption of the Chapmans' matching solution. This article presents a process-oriented approach to solving this problem in schizophrenia research.     

Action planning in the presence of distracting stimuli: an investigation into the time course of distractor effects

Humans have a remarkable capability to respond efficiently to a stimulus of interest despite other stimuli competing for neural resources. The current study investigated how the human system copes with distracting stimuli. During each trial, participants viewed 2 sequential stimuli that were each associated with a specific action based on an arbitrary mapping. The 1st stimulus served as a distractor, and the 2nd stimulus required a response (target). When the distractor preceded the target by more than a few hundred milliseconds, response latencies were slower when the 2 stimuli were associated with the same response. The authors propose that this negative compatibility effect stemmed from an inhibitory mechanism that the human system utilizes to prevent the distractor from eliciting an unwanted response.     

The role of familism in stress and coping processes among African American and White dementia caregivers: effects on mental and physical health.

OBJECTIVE: To explore how familism, burden, and coping styles mediate the relationships between ethnicity and the mental and physical health of caregivers. DESIGN: A probability sample of 65 White and 95 African Americans respondents caring for an older family member with dementia was used to test hypotheses from a sociocultural stress and coping model using path analysis. MAIN OUTCOME MEASURES: Measures of caregivers' health included subjective health, self-reported diseases, blood pressure, and heart rate. Mental health measures included self-reported depression and psychological symptoms. RESULTS: Contrary to the hypothesis, familism had an adverse effect on outcomes and was related to low education levels rather than to African American ethnicity. A buffering effect of active coping between being African American and diastolic blood pressure was found even after controlling for levels of education. CONCLUSIONS: Findings supported a core stress and coping model in which more behavior problems of care recipients were associated with poorer mental health of caregivers via greater burden and more use of avoidant coping. Results also demonstrate that this core model can be extended to physical health.     

Repetition of deliberate self-harm: a study of the characteristics and subsequent deaths in patients presenting to a general hospital according to extent of repetition

Repetition of deliberate self-harm (DSH) is common. Some patients repeat multiple times. We have investigated the characteristics of repeaters, and mortality in three groups of DSH patients by repetition status. Data collected by the Oxford Monitoring System for Attempted Suicide were used to examine the pattern of repetition of DSH patients presenting to a general hospital between 1990 and 1997. Each patient was tracked through the monitoring system with regard to repetition. Patients traceable through National Death Registers were followed up until 2000 with respect to mortality. A total of 4,167 patients were studied of which 1,022 (24.5%) repeated at least once during follow-up. Using multinomial regression, past history of DSH was the variable most strongly associated with frequent (4+) and less frequent (1-3) repetitions. Risk of suicide was significantly increased in females with frequent repetition (7.7% dying by suicide), compared with both those with 1-3 repetitions (2.3%) and those not repeating (1.0%). The analyses were repeated for the 2,167 patients with no past history of DSH at their first presentation. Using multinomial regression, personality disorder was the only variable that was associated with 4+ repetitions compared with no repetitions, although a number of variables distinguished between patients with 1-3 repetitions and no repeat episodes. For clinicians assessing DSH patients, past history of DSH is the best predictor of infrequent and frequent repetition. In patients with no past history of DSH the presence of personality disorder increases the risk of frequent repetition of DSH.     

Categorical perception of tactile distance

The tactile surface forms a continuous sheet covering the body. And yet, the perceived distance between two touches varies across stimulation sites. Perceived tactile distance is larger when stimuli cross over the wrist, compared to when both fall on either the hand or the forearm. This effect could reflect a categorical distortion of tactile space across body-part boundaries (in which stimuli crossing the wrist boundary are perceptually elongated) or may simply reflect a localised increased in acuity surrounding anatomical landmarks (in which stimuli near the wrist are perceptually elongated). We tested these two interpretations across two experiments, by comparing a well-documented bias to perceive mediolateral tactile distances across the forearm/hand as larger than proximodistal ones along the forearm/hand at three different sites (hand, wrist, and forearm). According to the ‘categorical’ interpretation, tactile distances should be elongated selectively in the proximodistal axis thus reducing the anisotropy. According to the ‘localised acuity’ interpretation, distances will be perceptually elongated in the vicinity of the wrist regardless of orientation, leading to increased overall size without affecting anisotropy. Consistent with the categorical account, we found a reduction in the magnitude of anisotropy at the wrist, with no evidence of a corresponding localised increase in precision. These findings demonstrate that we reference touch to a representation of the body that is categorically segmented into discrete parts, which consequently influences the perception of tactile distance.     

We can work it out: Group decision‐making builds social identity and enhances the cognitive performance of care residents

Group‐based interventions have been argued to slow the cognitive decline of older people residing in care by building social identification and thereby increasing motivation and engagement. The present study explored the identity–cognition association further by investigating the impact of a group decision‐making intervention on cognition. Thirty‐six care home residents were assigned to one of three conditions: an Intervention in which they made decisions about lounge refurbishment as a group, a Comparison condition in which staff made these decisions, or a no‐treatment Control. Cognitive function, social identification, home satisfaction, and lounge use were measured before and after the intervention. Participants in the Intervention condition showed significant increases on all measures, and greater improvement than participants in both Comparison and Control conditions. Consistent with social identity theorizing, these findings point to the role of group activity and social identification in promoting cognitive integrity and well‐being among care residents.