Competing Neural Responses for Auditory and Visual Decisions

Why is it hard to divide attention between dissimilar activities, such as reading and listening to a conversation? We used functional magnetic resonance imaging (fMRI) to study interference between simple auditory and visual decisions, independently of motor competition. Overlapping activity for auditory and visual tasks performed in isolation was found in lateral prefrontal regions, middle temporal cortex and parietal cortex. When the visual stimulus occurred during the processing of the tone, its activation in prefrontal and middle temporal cortex was suppressed. Additionally, reduced activity was seen in modality-specific visual cortex. These results paralleled impaired awareness of the visual event. Even without competing motor responses, a simple auditory decision interferes with visual processing on different neural levels, including prefrontal cortex, middle temporal cortex and visual regions

Pharmacological Fingerprints of Contextual Uncertainty

Successful interaction with the environment requires flexible updating of our beliefs about the world. By estimating the likelihood of future events, it is possible to prepare appropriate actions in advance and execute fast, accurate motor responses. According to theoretical proposals, agents track the variability arising from changing environments by computing various forms of uncertainty. Several neuromodulators have been linked to uncertainty signalling, but comprehensive empirical characterisation of their relative contributions to perceptual belief updating, and to the selection of motor responses, is lacking. Here we assess the roles of noradrenaline, acetylcholine, and dopamine within a single, unified computational framework of uncertainty. Using pharmacological interventions in a sample of 128 healthy human volunteers and a hierarchical Bayesian learning model, we characterise the influences of noradrenergic, cholinergic, and dopaminergic receptor antagonism on individual computations of uncertainty during a probabilistic serial reaction time task. We propose that noradrenaline influences learning of uncertain events arising from unexpected changes in the environment. In contrast, acetylcholine balances attribution of uncertainty to chance fluctuations within an environmental context, defined by a stable set of probabilistic associations, or to gross environmental violations following a contextual switch. Dopamine supports the use of uncertainty representations to engender fast, adaptive responses. \ua9 2016 Marshall et al

Structure-function studies on gastrointestinal hormones: I. Synthesis of secretin analogs and their biological and immunological properties

Syntheses by conventional procedures of the three analogs corresponding to the porcine secretin sequence crossed at position 6 by the N-terminal hexapeptide sequences of VIP, GIP, and glucagon are described, viz., Ala4,Val5-, Tyr1,Ala2,Glu3-, and Gln3-secretin (VIP-SN, GIP-SN, and GLU-SN). The analog Phe1,Phe2,Trp3,Lys4-secretin (SOMA-SN), designed on the basis of the surprising homology of the sequence portions 10–13 of somatostatin and 5–8 of secretin, was also prepared. Finally, the synthesis of Nα-3-(4-hydroxyphenyl)propionyl-β-alanyl-secretin (DATA-SN), a tracer suitable for secretin radioimmunoassay and as an N-terminus modified secretin analog, is reported. The analogs are compared, in terms of their biological and immunological properties in different assay systems, with pure synthetic secretin

Local antimicrobial therapy after initial periodontal treatment

Aim: The aim of this single-blind, randomized, parallel-designed clinical trial (RCT) was to evaluate the clinical and microbiological effects of three sustained-release biodegradable polymers delivered into periodontal pockets following initial periodontal therapy. Methods: Forty-seven patients (28 females and 19 males) with a mean age of 51 years (range 29-71) underwent a periodontal examination at baseline (i.e. Week 0) and after 18 weeks. This included the assessment of the Plaque Index (PlI), Bleeding on Probing (BOP), Pocket Probing Depths (PPD) and Probing Attachment Levels (PAL) at six sites per tooth. Two to 4 months prior to baseline, all subjects had received initial periodontal therapy including motivation, instruction in oral hygiene practices and full-mouth scaling and root planing. At the treatment appointment (i.e. Week 2), the patients were randomly assigned to receive either Atridox™, Elyzol® Dental Gel or PerioChip® at all residual periodontal pockets with a probing depth ≥ 5 mm and concomitant BOP. In accordance with the manufacturer's recommendations, Elyzol® Dental Gel was applied for a second time 7 days later. In addition to the clinical evaluation, subgingival microbiological samples were collected prior to treatment (i.e. Week 2) and at Weeks 4 and 18. Analysis of variance/covariance was used to evaluate changes from baseline to Week 18 for the clinical parameters. Results: Between the baseline and 18-week examinations, subjects treated with Atridox showed a significantly greater gain in mean PAL of 0.33 mm ± 0.09 (SD) than subjects treated with Elyzol® Dental Gel [0.03 mm ± 0.09 (SD)] (p = 0.03). However, the gain in PAL of 0.16 mm ± 0.10 (SD) found after PerioChip® application did not differ significantly from that obtained following the application of Atridox™ (p = 0.27). Of the sites treated with Atridox™, 42% gained ≥1 mm PAL and 9% ≥ 2 mm PAL as opposed to the sites treated with Elyzol® Dental Gel, in which 34% gained ≥ 1 mm PAL and 8% gained ≥ 2 mm PAL. Of the sites treated with PerioChip®, 36% gained ≥ 1 mm and 6% gained ≥ 2 mm PAL following a completed initial periodontal therapy. Conclusions: The application of the three biodegradable sustained release devices tested following initial periodontal therapy resulted in a statistically significant gain in mean PAL for Atridox™ and a significant reduction in PPD for all three devices during the study period. Furthermore, when sites treated with Atridox™ were compared with sites treated with Elyzol®, a significant difference in mean PAL gain (0.3 mm) was observed. © Blackwell Munksgaard, 2002.link_to_subscribed_fulltex