Dissociating the role of the dorsolateral prefrontal and anterior cingulate cortex in cognitive control

Theories of the regulation of cognition suggest a system with two necessary components: one to implement control and another to monitor performance and signal when adjustments in control are needed. Event-related functional magnetic resonance imaging and a task-switching version of the Stroop task were used to examine whether these components of cognitive control have distinct neural bases in the human brain. A double dissociation was found. During task preparation, the left dorsolateral prefrontal cortex (Brodmann's area 9) was more active for color naming than for word reading, consistent with a role in the implementation of control. In contrast, the anterior cingulate cortex (Brodmann's areas 24 and 32) was more active when responding to incongruent stimuli, consistent with a role in performance monitoring.     

A discrete-event computer model of feline herpes virus within cat populations

The purpose of this work was to study the epidemiology of feline herpes virus (FHV), which causes a respiratory disease within natural populations of domestic cats. A stochastic model was constructed using discrete-events simulation. Two habitats (rural vs. urban) were simulated, featuring different demographic, spatial and social patterns. The evolution of immunity in individuals was reproduced, allowing for the random recrudescence of latent infections (influenced by environment and reproduction). Hypotheses concerning the circulation of FHV were examined regarding the role of host density and the possibility of reinfection of host. Uncertainty analyses were performed on the basis of replicated Monte Carlo sampling. The results were in good agreement with serologic data from a long-term study conducted on five populations in France. The model satisfactorily reproduced the variability of natural immunity, and the epidemic features observed. The simulations have shown that FHV can persist in small populations (because of its capacity of reactivation leading to epidemics). However, the impact on demography was not dramatic. The most important parameters in determining change in epidemiology of FHV were: transmission rate corresponding to ‘friendly’ contacts, and the recrudescence rate of FHV. However, an interaction between these two parameters did not allow estimation of their values.     

Chronic idiopathic inflammatory bowel diseases of the horse

A review of reported cases of inflammatory bowel diseases (IBDs) of horses for which no etiology was identified included cases of granulomatous enteritis (GE), multisystemic eosinophilic epitheliotropic disease (MEED), lymphocytic-plasmacytic enterocolitis (LPE), and idiopathic eosinophilic enterocolitis (EC). The terms EC and MEED were both used to describe a disease in horses characterized by infiltration of intestine and extraintestinal tissues with eosinophils. We use EC to describe IBD characterized by only intestinal infiltration by eosinophils. Horses with GE, MEED, or LPE are usually examined because of weight loss and depression, but horses with EC are usually examined because of signs of abdominal pain. Typically, horses with IBD have low concentrations of serumal proteins, especially albumin, and fail to adequately absorb glucose or xylose. Antemortem diagnosis of IBD can only be made by histologic examination of affected intestine. In some cases, antemortem diagnosis is made from histologic examination of rectal mucosa obtained by biopsy. Suspected causes of IBD in the horse include abnormal immune response to bacterial, viral, parasitic, or dietary antigens. Most horses with IBD do not survive, but horses with EC are more likely than those with LPE, MEED, or GE to respond to treatment. Successful treatments of horses with IBD include resection of grossly affected intestine and administration of corticosteroids.     

Medical Management of Right Dorsal Colitis in 5 Horses: A Retrospective Study (1987–1993)

Right dorsal colitis in horses has been associated with administration of phenylbutazone. Although reports of right dorsal colitis in this species have described surgical treatment associated with a poor prognosis, we have had success treating this condition medically. This report describes 5 horses with right dorsal colitis confirmed during celiotomy that were initially managed medically. All horses had a history of intermittent abdominal pain; weight loss was noted in only 1 horse. The doses (2.0 to 4.6 mg/kg PO bid) and duration (5 to 30 days) of administration of phenylbutazone were not unusually high relative to those recommended (4.4 mg/kg PO bid). Hypoproteinemia and hypoalbuminemia were observed in all horses at the time of admission; packed cell volume was low in 4 horses, and hypocalcemia was also observed in 4 horses. Three of 5 horses (60%) appeared to respond to dietary management and discontinuation of administration of nonsteroidal anti-inflammatory drugs. Dietary management consisted of feeding pelleted feed, and restricting or eliminating roughage for a period of at least 3 months. Two horses developed strictures of the right dorsal colon. One horse that developed a colonic stricture, possibly because its owners did not comply with recommendations for management, was subsequently treated surgically. The remaining horse that developed a stricture of the right dorsal colon was euthanized. These data indicate that some horses with right dorsal colitis can be successfully managed with medical treatment.     

Magnetoencephalography: detection of the brain's electrical activity with a superconducting magnetometer

Measurements of the brain's magnetic field, called magnetoencephalograms (MEG's), have been taken with a superconducting magnetometer in a heavily shielded room. This magnetometer has been adjusted to a much higher sensitivity than was previously attainable, and as a result MEG's can, for the first time, be taken directly, without noise averaging. MEG's are shown, simultaneously with the electroencephalogram (EEG), of the alpha rhythm of a normal subject and of the slow waves from an abnormal subject. The normal MEG shows the alpha rhythm, as does the EEG, when the subject's eyes are closed; however, this MEG also shows that higher detector sensitivity, by a factor of 3, would be necessary in order to clearly show the smaller brain events when the eyes are open. The abnormal MEG, including a measurenment of the direct-current component, suggests that the MEG may yield some information which is new and different from that provided by the EEG.     

Quantitation of resistance of cucumbers and cantaloups toPseudoperonospora Cubensis

Of 14 varieties and lines of cucumber and seven of cantaloup tested for resistance againstPseudoperonospora cubensis, only the cucumbers Poinsett and Chipper were found to be highly resistant. Growth chamber studies showed that resistance of young as well as of old (> 8-leaf-stage) plants was stable under considerably high (300 sporangia/cm²) inoculum loads. Resistance was conferred by both restriction of fungal growth and prevention of sporangial formation.     

Puromycin and cycloheximide: different effects on hippocampal electrical activity

Abstract. Mice were injected in the temporal region of the brain with cycloheximide or puromycin; both agents markedly inhibit protein synthesis in the brain. Recordings of electrical activity were made in the hippocampal region 5 hours after injection of these drugs. The amplitude and frequency observed in records from mice injected with cycloheximide were indistinguishable from those injected with saline alone. Records from puromycin-injected mice were strikingly abnormal. This finding may contribute to the differences in behavioral effects of intracerebral injections of the two inhibitors of protein synthesis studied.