Modality-specific control processes in verbal versus spatial working memory.

Over the past decade, neuroimaging and electrophysiological studies of working memory (WM) have made progress in distinguishing the neural substrates of central executive (CE) functions from substrates of temporary storage subsystems. However, the degree to which CE-related processes and their substrates may be further fractionated is less clear. The present study measured event-related potentials (ERPs) in a running memory paradigm, to study modality-specific CE-related processes in verbal and spatial WM. Participants were asked to remember either verbal (digit identity) or spatial (digit location) information for the first or last three items in a variable length sequence of spatially distributed digit stimuli. Modality-specific WM demand-sensitive ERP amplitude effects were selectively observed over left prefrontal areas under verbal WM performance and over right prefrontal areas under spatial WM performance. In addition, distinct patterns of item-by-item sensitivity under high-CE-demand conditions suggested qualitatively different processing strategies for verbal versus spatial tasks. These results suggest that both modality-specific and task-general CE-related processes are likely operational in many WM situations and that careful dissociative methods will be needed to properly further fractionate and characterize these component CE-related processes and their neurological substrates.

Control processes in verbal working memory: an event-related potential study.

Event-related potentials (ERPs) were recorded using a large electrode array while subjects engaged in tasks designed to dissociate control from storage/maintenance processes in verbal working memory (WM). Increased ERP negativity (450-900 ms post-stimulus onset) over left frontal regions emerged only when required dynamic updating/revision of WM stores was initiated, with augmentation of right frontal negativity in the same epoch relative to more general overall task demands. Increased ERP positivity in a similar time window over parietal regions reflected initiation of required rehearsal/maintenance of memory set contents, with progressive amplitude increases with repeated dynamic updating/revision of memory stores, suggesting increased effortful activity to resist proactive interference effects. These findings are consistent with a left frontal-parietal network for process control in verbal working memory.

Treatment of a first episode of psychotic illness with quetiapine: an analysis of 2 year outcomes.

BACKGROUND: The first episode of a psychotic disorder provides a unique opportunity to initiate optimal treatment but when a new medication becomes available, little data exist to guide the appropriate use in this population. OBJECTIVES: The objectives were to determine the optimal doses and titration of quetiapine for this group and to measure outcomes (including symptom response, social functioning, mood alterations, motor symptoms, metabolic parameters and cognitive functioning) over 2 years of treatment with quetiapine. DESIGN: Thirty nine subjects with a first episode of psychosis referred to the Nova Scotia Early Psychosis Program in Halifax, Canada, were invited to participate in this study. Standardized clinical, laboratory, and neuropsychological assessments were performed at baseline and following treatment with quetiapine at intervals out to 2 years. RESULTS: Quetiapine was effective in treating the psychotic and mood symptoms while not causing extra-pyramidal signs or symptoms (EPSS). Pre-existing motor dysfunction improved. No anticholinergic medications were required. Several domains of cognitive function also improved (sustained attention, the number of perseverative errors, visuomotor speed and sequencing, verbal fluency and verbal memory). Weight gain was observed along with increases in cholesterol levels but there was no glucose dysregulation. CONCLUSIONS: The results of this two year, naturalistic study of people with a first episode of psychosis indicated that quetiapine was well tolerated and effective for this population. Significant improvements in cognitive functioning also provided evidence for potential longer-term benefits of early and optimal treatment with this agent. However, monitoring metabolic parameters, as recommended for other atypicals, is likely prudent.

The novel analgesic, F 13640, produces intra- and postoperative analgesia in a rat model of surgical pain.

F 13640 is a newly discovered high-efficacy 5-HT(1A) receptor agonist that produces exceptional analgesia in animal models of tonic and chronic, nociceptive and neuropathic pains by novel molecular and neuroadaptive mechanisms. Here we examined the effects of F 13640 and remifentanil (0.63 mg/kg with either compound) when injected i.p. either before or 15 min after rats underwent orthopedic surgery. Surgery consisted of the drilling of a hole in the calcaneus bone and of an incision of the skin, fascia and plantar muscle of one foot. During surgery, the concentration of volatile isoflurane was progressively incremented depending on the animal's response to surgical maneuvers. Other experiments examined the dose-dependent effects of F 13640 (0.04 to 0.63 mg/kg) on surgical pain as well as on the Minimum Alveolar Concentration of isoflurane. Both F 13640 and remifentanil markedly reduced the intra-operative isoflurane requirement. F 13640 also reduced measures of postoperative pain (i.e., paw elevation and flexion). With these postoperative measures, remifentanil produced short-lived analgesia followed by hyperalgesia. F 13640 significantly reduced both surgical pain and the isoflurane Minimum Alveolar Concentration from 0.16 mg/kg onward. F 13640 produced powerful intra- and postoperative analgesia in rats undergoing orthopedic surgery. Unlike the opioid, remifentanil, F 13640 caused no hyperalgesia with ongoing postoperative pain, and should remain effective with protracted postoperative use.

Electrophysiological correlates of object categorization: back to basics.

The time course of visual object categorization as a function of electrophysiological activity in the brain was investigated using a variant of the "oddball" design. Category level was manipulated by sequentially presenting subordinate, basic or superordinate target objects among a variety of non-target objects. It was found that superordinate categorizations were performed more quickly and differentiated from basic level categorizations in amplitude early in visual processing (320-420 ms). In contrast, subordinate categorizations took longer to perform and differentiated from basic level categorizations in amplitude and latency at later stages (450-550 ms). Notably, these effects were observed using the same objects categorized at different levels suggesting that visually categorizing objects at varying levels of abstraction engaged specific cognitive processes. These results are consistent with research on rapid visual categorization that challenges the generality of basic category level superiority effects.

Does opiate premedication influence postoperative analgesia? A prospective study.

The influence of opiate premedication on analgesic requirements postoperatively was investigated. Out of 98 patients with a lumbar disc prolapse 50 were premedicated with flunitrazepam orally, 48 with pethidine and triflupromazine intramuscularly. The operations were performed under inhalational anaesthesia. The average time up to the first demand for an analgesic was longer following opiate premedication (351 vs. 219 min). Only 45.8% of the patients treated with opiates demanded analgesics postoperatively, compared to 80.0% of those who had a benzodiazepine premedication (P less than 0.01). These clinical data confirm the experimental evidence that pretreatment with opiates diminishes the sustained hyperexcitation of the central nervous system caused by peripheral lesions.

The McGill Pain Questionnaire--German version. A study on cancer pain.

The McGill Pain Questionnaire, widely used in English-speaking countries, has been translated into German. The objective in translating the questionnaire was to produce a translation of the words while keeping the expression of the pain quality and intensity. The results of our present study with a German-speaking cancer pain population, concerning the choice of words and pain rating values, are comparable with those of similar English-speaking patients. The superiority of this multidimensional verbal questionnaire in analysis of pain qualities over unidimensional pain intensity scales was proved. The therapeutic effect of peridural opiate analgesia was measured in 30 patients with intractable cancer pain after they had completed the questionnaire. After 5 days of therapy, there was an average of 70% relief of the total pain experience, with best results obtained in patients with bone pain in the lumbo-sacral region.