The effect of cocaine on rotarod performance in male C57BL/6J mice.

There is surprisingly little research examining the effect of cocaine on motor learning. Given that changes in motor activity can confound behavioral assays of learning and memory a direct assessment of cocaine on motor learning seems warranted. The present study was conducted to examine the effect of cocaine on motor learning using an accelerating rotarod test in adult male C57BL/6J mice. Mice were given an injection of either saline or cocaine (10mg/kg, i.p.) for 6 consecutive days prior to rotarod training (Pre-exposure). In the first phase of training (Phase I), mice were given an injection of either saline or cocaine 10min prior to the start of each day's training on the rotarod for 6 consecutive days. In the second phase (Phase II), half the animals continued to receive the same drug during training, while the other half were switched from saline to cocaine or from cocaine to saline. All mice exhibited motor learning as evidenced by an increased latency to fall across days. Animals that received cocaine injections exhibited significantly longer latencies to fall on days 3-6 compared to those mice receiving saline. This enhanced performance was lost when cocaine-injected animals were switched to saline on day 7. It is hypothesized that the performance enhancing effects of cocaine are due to the increased stamina and/or psychomotor stimulation and not the result of enhanced motor learning as the increment in performance was lost when the drug was discontinued.

Perceptual organization and visual search processes during target detection task performance in schizophrenia, as revealed by fMRI.

BACKGROUND: Past studies of perceptual organization in schizophrenia have demonstrated impairments binding fragmented stimulus components into unified representations. ERP and fMRI data indicate that even under conditions of adequate behavioral task performance, significant and meaningful changes in cortical and subcortical activation are present. Here, we examined, using fMRI, activation differences on a visual task wherein feature grouping was a precursor to the formation of distinct groups in the service of target location and identification. METHOD: Fourteen schizophrenia patients and 16 healthy controls completed a target detection task with 2 conditions: one in which target-distractor grouping facilitates detection (the Isolated condition) and one in which it hinders detection (the Embedded condition). Stimuli were blocked by condition. Accuracy and RT data were obtained in addition to fMRI data. RESULTS: Patients and controls did not differ significantly in accuracy or RT in either condition. Within this context, controls demonstrated greater recruitment of brain regions involved in visual-spatial processing, and the groups differed in activity in areas known to support visual search, visual analysis, decision making and response generation. CONCLUSION: These findings are consistent with past data indicating reduced processing of stimulus organization, and the subsequent use of inefficient visual search strategies, even under conditions when behavioral performance is at a high level and matches that of healthy controls.

An fMRI examination of visual integration in schizophrenia.

Behavioral and electrophysiological studies of schizophrenia have consistently demonstrated impairments in the integration of visual features into unified perceptual representations. Specific brain regions involved in this dysfunction, however, remain to be clarified. This study used functional Magnetic Resonance Imaging (fMRI) to examine the relative involvement of visual cortex areas (involved in form perception) and parietal and frontal regions (involved in attention), in the visual integration impairment in schizophrenia. Fourteen patients with schizophrenia and 14 healthy controls were compared on behavioral performance and data acquired via fMRI while completing a contour integration task that had previously been used to identify a visual integration deficit in schizophrenia. The schizophrenia patients demonstrated poorer visual integration than controls. Analyses of peak signal change indicated that while the groups were equivalent in area V1, the schizophrenia group demonstrated reduced signal in areas V2-V4, which are the earliest regions sensitive to global configurations of stimuli. Moreover, whereas the control group demonstrated greater recruitment of prefrontal and parietal areas during perception of integrated forms compared to random stimuli, the schizophrenia group demonstrated greater recruitment of frontal regions during perception of random stimuli. The two groups differed on brain regions involved in form perception even when they were matched on accuracy levels. The visual integration disturbance in schizophrenia involves both deficient basic visual processes (beginning as early as occipital region V2), as well as reduced feedback from visual attention regions that normally serves to amplify relevant visual representations relative to irrelevant information.

Attention shaping: a reward-based learning method to enhance skills training outcomes in schizophrenia.

Disturbances in sustained attention commonly interfere with the ability of persons with schizophrenia to benefit from evidence-based psychosocial treatments. Cognitive remediation interventions have thus far demonstrated minimal effects on attention, as have medications. There is thus a gap between the existence of effective psychosocial treatments and patients' ability to effectively engage in and benefit from them. We report on the results of a multisite study of attention shaping (AS), a behavioral intervention for improving attentiveness and learning of social skills among highly distractible schizophrenia patients. Patients with chronic schizophrenia who were refractory to skills training were assigned to receive either the UCLA Basic Conversation Skills Module (BCSM) augmented with AS (n = 47) or in the standard format (n = 35). AS, a reward-based learning procedure, was employed to facilitate patients' meeting clearly defined and individualized attentiveness and participation goals during each session of a social skills training group. Primary outcome measures were observational ratings of attentiveness in each session and pre- and post-BCSM ratings of social skill and symptoms. Patients receiving social skills training augmented with AS demonstrated significantly more attentiveness in group sessions and higher levels of skill acquisition; moreover, significant relationships were found between changes in attentiveness and amount of skills acquired. Changes in attentiveness were unrelated to level or change in antipsychotic medication dose. AS is an effective example of supported cognition, in that cognitive abilities are improved within the environmental context where the patient is experiencing difficulty, leading to gains in both attention and functional outcome.

Development and validation of a World-Wide-Web-based neurocognitive assessment battery: WebNeuro.

Assessment of neurocognitive functioning is a critical task in many clinical, educational, service, and industrial settings. We report on descriptive and validation data of a new, World-Wide-Web-based, comprehensive battery of neurocognitive functioning, WebNeuro, that can be used in both applied and research contexts. Fifty healthy control participants completed both WebNeuro, and an established non-Internet-based computerized cognitive assessment battery, IntegNeuro, that uses a touchscreen platform. Results indicated comparability across the two batteries, in terms of critical single test scores, factor analysis derived indices,overall performance scores, and sex differences. These results support the validity of WebNeuro as a neurocognitive assessment measure. Advantages of its use in applied and research settings are discussed.