Pyramidal cells in the CA1 hippocampal region displayed transient network oscillations (200 hertz) during behavioral immobility, consummatory behaviors, and slow-wave sleep. Simultaneous, multisite recordings revealed temporal and spatial coherence of neuronal activity during population oscillations. Participating pyramidal cells discharged at a rate lower than the frequency of the population oscillation, and their action potentials were phase locked to the negative phase of the simultaneously recorded oscillatory field potentials. In contrast, interneurons discharged at population frequency during the field oscillations. Thus, synchronous output of cooperating CA1 pyramidal cells may serve to induce synaptic enhancement in target structures of the hippocampus.

No abstract

Neocortical high-voltage spike-and-wave discharges (HVS) in the rat are an animal model of petit mal epilepsy. Genetic analysis of total duration of HVS (s/12 hr) in reciprocal F1 and F2 hybrids of F344 and BN rats indicated that the phenotypic variability of HVS cannot be explained by a simple, monogenic Mendelian model. Biometrical analysis suggested the presence of additive, dominance, and sex-linked-epistatic effects, buffering maternal influence, and heterosis. High correlation was observed between average duration (s/episode) and frequency of occurrence of spike-and-wave episodes (n/12 hr) in parental and segregating generations, indicating that common genes affect both duration and frequency of the spike-and-wave pattern. We propose that both genetic and developmental-environmental factors control an underlying quantitative variable, which, above a certain threshold level, precipitates HVS discharges. These findings, together with the recent availability of rat DNA markers for total genome mapping, pave the way to the identification of genes that control the susceptibility of the brain to spike-and-wave discharges.

This analysis aimed to assess the relationship between race and clinical response to long-acting, injectable risperidone treatment in patients with schizophrenia or schizoaffective disorder. In a 12-week, randomized, double-blind study, patients with schizophrenia or schizoaffective disorder received placebo or long-acting risperidone (25, 50 or 75 mg every 2 weeks). Data were stratified by race as identified by demographic information: Caucasian, African-American or Other. Psychotic symptoms were assessed by the Positive and Negative Syndrome Scale (PANSS); movement disorders by the Extrapyramidal Symptom Rating Scale (ESRS); adverse events (AEs) were reported spontaneously. Data were available for 439 patients: 193 Caucasian (44%), 174 (40%) African-American and 72 (16%) Other patients. Baseline characteristics were similar between racial groups, as were study completion rates (overall: 30% placebo; 48% long-acting risperidone). There was a significant effect of treatment (P<0.001), but not of race, on improvement in PANSS total scores from baseline to endpoint. ESRS scores were low throughout the study, and no significant impact of race was observed. Overall rates of AEs were similar among the racial groups. Race did not appear to impact the efficacy and tolerability of long-acting risperidone.