Vision, cognition, and walking stability in young adults

Downward gazing is often observed when walking requires guidance. This gaze behavior is thought to promote walking stability through anticipatory stepping control. This study is part of an ongoing effort to investigate whether downward gazing also serves to enhance postural control, which can promote walking stability through a feedback/reactive mechanism. Since gaze behavior alone gives no indication as to what information is gathered and the functions it serves, we aimed to investigate the cognitive demands associated with downward gazing, as they are likely to differ between anticipatory and feedback use of visual input. To do so, we used a novel methodology to compromise walking stability in a manner that could not be resolved through modulation of stepping. Then, using interference methodology and neuroimaging, we tested for (1) interference related to dual tasking, and (2) changes in prefrontal activity. The novel methodology resulted in an increase in the time spent looking at the walking surface. Further, while some dual-task interference was observed, indicating that this gaze behavior is cognitively demanding, several gaze parameters pertaining to downward gazing and prefrontal activity correlated. These correlations revealed that a greater tendency to gaze onto the walking surface was associated with lower PFC activity, as is expected when sensory information is used through highly automatic, and useful, neural circuitry. These results, while not conclusive, do suggest that gazing onto the walking surface can be used for purposes other than anticipatory stepping control, bearing important motor-control and clinical implications.

Role of Anionic Chromium Species in Leather Tanning

Chrome tanned leathers are definitely unique in comparison with leather made from any other known tanning agents, especially in terms of thermal stability, cost and its reactive mechanism with collagen fibers. In our current studies, self basifying chrome tanning materials masked with different percentages of organic acid were prepared and applied after the de-liming stage of leather processing. This eliminated the need for pickling and basification steps. Tanned leathers resisted shrinkage up to 103 and 105±2°C while conventional chrome tanned leathers resisted up to 108±2°C. Also, interaction of anionic chrome species in tanning was studied. It was observed that the percentage of anionic species in the experimental chrome tanning material was higher than conventional chrome tanning material and the shrinkage temperature achieved by application of experimental tanning material proves that anionic species do involve in tanning. Tanned leathers were crusted and analysed for strength and organoleptic properties.

Organophosphate intoxication in C. elegans reveals a new route to mitigate poisoning through the modulation of determinants responsible for nicotinic acetylcholine receptor function

Plasticity is a reactive mechanism that allows the adaptation of organisms to changing environmental cues. The exploitation of this physiological process has a clear benefit to promote the recovery from a wide range of neurological disorders. Here, we show that plasticity-promoting regimes provide candidate mechanisms to supplement the classically used antidotes for anti-cholinesterase poisoning. These neurotoxins inhibit acetylcholinesterase, causing the overstimulation of cholinergic transmission at synapses and neuromuscular junctions. The model organism C. elegans exhibits organophosphate-induced mitigating plasticity that impacts on the recovery of neuromuscular phenotypes, initially impaired by the drug. This is underpinned by overstimulation of nicotinic receptors at the neuromuscular junction. Intrinsic determinants of receptors location and sensitivity modulate the extent of plasticity in the context of persistent cholinergic stimulation. Our results indicate that pharmacological intervention of nicotinic receptors and/or scaffolding proteins that support receptor function might provide a novel treatment route for anti-cholinesterase poisoning.

Reward encourages reactive, goal-directed suppression of attention

Stimuli that signal large reward are more likely to capture attention and gaze than stimuli that signal lesser or no reward, even when capture counterproductively prevents reward delivery. This suggests that a stimulus’s signalling relationship with reward (the contingency between stimulus presentation and reward delivery) is a potent influence on selective attention. Recent studies have also implicated a stimulus’s response relationship with reward (the reward-related consequences of attending to a stimulus) in reducing capture by signals of reward. Here we show that this response pathway modulates capture by encouraging a reactive, goal-directed distractor suppression process. In a rewarded visual search task, participants demonstrated an oculomotor preference away from a distractor that had a negative response relationship with high reward (looking at the distractor caused reward to be cancelled) and towards a distractor that had no such negative response relationship, providing evidence for the role of the response relationship in suppressing capture by reward-related distractors. Analysis of the temporal dynamics of eye-movements suggests that this distractor suppression process operates via a reactive mechanism of rapid disengagement (Experiment 1). Consistent with a goal-directed mechanism, the influence of the response relationship was eliminated when reward was unavailable (Experiment 2). These findings highlight the multifaceted role of learned stimulus-reward relationships in attentional selection.