Traumatic spinal cord injuries ultimately result in an inhibitory environment that prevents axonal regeneration from occurring. A low concentration administration of paclitaxel has been previously shown to promote axonal extension and attenuate the upregulation of inhibitory molecules after a spinal cord injury. In this study we incorporated paclitaxel into electrospun poly(l-lactic acid) (PLA) microfibers and established that a local release of paclitaxel from aligned, electrospun microfibers promotes neurite extension in a growth-conducive and inhibitory environment. Isolated dorsal root ganglion cells were cultured for five days directly on tissue culture polystyrene surface, PLA film, random, or aligned electrospun PLA microfibers (1.44 ± 0.03 µm) with paclitaxel incorporated at various concentrations (0 – 5.0% w/w in reference to fiber weight). To determine the effect of a local release of paclitaxel, paclitaxel-loaded microfibers were placed in CellCrown™ inserts above cultured neurons. Average neurite extension rate was quantified for each sample. A local release of paclitaxel maintained neuronal survival and neurite extension in a concentration-dependent manner when coupled with aligned microfibers when cultured on laminin or an inhibitory surface of aggrecan. Our findings provide a targeted approach to improve axonal extension across the inhibitory environment present after a traumatic injury in the spinal cord.
Cognitive control involves flexibly combining multiple sensory inputs with task-dependent goals during decision making. Several tasks have been proposed to examine cognitive control, including Stroop, Eriksen-Flanker, and the Multi-source interference task. Because these tasks have been studied independently, it remains unclear whether the neural signatures of cognitive control reflect abstract control mechanisms or specific combinations of sensory and behavioral aspects of each task. To address this question, here we recorded invasive neurophysiological signals from 16 subjects and directly compared the three tasks against each other. Neural activity patterns in the theta and high-gamma frequency bands differed between incongruent and congruent conditions, revealing strong modulation by conflicting task demands. These neural signals were specific to each task, generalizing within a task but not across tasks. These results highlight the complex interplay between sensory inputs, motor outputs, and task demands and argue against a universal and abstract representation of conflict.
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