Persisting inhibition biases efficient rule inference under uncertainty

Introduction

Task set inhibition supports optimal switching among tasks by actively suppressing the interference from recently executed competing task sets. It is typically studied in cued task-switching paradigms where there is no uncertainty about the task set or rule to prepare for on each trial. While inhibition has been shown to influence the speed and the accuracy of task execution, affecting task set retrieval, preparation, or implementation in conditions of task set switching, it remains uninvestigated whether it also affects rule selection under uncertainty.

Methods

We implemented an ad-hoc four-rule card sorting task and categorized the rules selected by participants after a rule shift according to the recency of their last usage. We included a measure of working memory capacity (WMC) to control for its involvement in the rule selection process.

Results

Participants exhibited a reduced preference for recently abandoned rules than less recently abandoned ones. Furthermore, we found that such a preference was not associated with WMC.

Discussion

The results suggest that decision-making processes underlying rule inference and selection may be influenced by task-set inhibition, configuring as a conflict adjustment mechanism to the sequential history of rules application.

Rosiglitazone reverses increased duodenal inhibitory response in spontaneously hypertensive rats

BACKGROUND

Thiazolidinediones (TZDs) including rosiglitazone (ROSI) are insulin sensitizing agents with beneficial gastrointestinal effects. However, no studies are available on TZDs effect in gastrointestinal motility. We evaluated the effects of ROSI on gastrointestinal inhibitory neurotransmission focusing on the modulatory roles of nitric oxide synthase/nitric oxide (NOS/NO) and heme oxygenase/carbon monoxide (HO/CO) pathways.

METHODS

Spontaneously hypertensive rats (SHR) were used as model of insulin resistance. Duodenal strips were obtained from vehicle-treated SHR, ROSI-treated SHR (5 mg kg(-1) by gavage daily per 6 weeks), and Wistar Kyoto (WKY). Inhibitory responses to electrical field stimulation (EFS) were evaluated in the presence of HO inhibitor zinc protoporphyrin IX (ZnPPIX, 10 μmol L(-1)) or NOS inhibitor N(G)-nitro-L-arginine (L-NNA, 100 μmol L(-1)), alone and in combination. Protein levels of HO and NOS isoforms were evaluated by immunohistochemistry and western blot analysis.

KEY RESULTS

Basal responses to EFS were significantly increased in duodenum strips from vehicle-treated SHR vs WKY. This effect was reversed in ROSI-treated SHR. The EFS-mediated relaxation was comparably reduced by ZnPPIX in WKY and SHR, but not in ROSI-treated SHR animals. The L-NNA reduced EFS response to a similar extent in WKY and ROSI -treated SHR, but its effect was significantly higher in vehicle-treated SHR. Expression of HO-1 protein was significantly lower, whereas HO-2 protein levels were unchanged in ROSI-treated SHR with respect to vehicle-treated SHR. Finally, increased levels of nNOS in vehicle-treated SHR were reduced in ROSI-treated SHR.

CONCLUSIONS & INFERENCES

Chronic ROSI treatment reverses increased SHR duodenal inhibitory response acting on CO and NO components.

[Serological typing of Salmonella in the Aquilano area]

During the years '80 and '81 16 stocks of Salmonellae are been isolated from 1200 coprocoltures coming from no hospital subjects in the Sanitary and Prophylaxis Laboratory. The percentage of positivity(1, 33%) is par from the last research carried out in 1977 and it is par from other researches in other countries. We confirm that women, more than men, are bearer(1, 65% against 1, 10%) the isolated species are 7, with a slight prevalence of the Salmonella anatum.