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We have used event-related potentials (ERP) to assess cerebral activity following mild traumatic brain injuries in 20 college athletes practising contact sports. Concussion victims showed a striking decrease in P300 amplitude, an effect presumed to reflect alterations in attentional-cognitive processes. Moreover, the degree of impairment was strongly related to the severity of post-concussion symptoms. Our data suggest that concussions cause objectively measurable changes in the electrophysiological markers of brain activity and hence in the functions of the structures from which they originate. ERPs may thus constitute a reliable method to accurately monitor the clinical course and recovery of head injuries in athletes.

In order to assess whether cerebral anomalies may be observed in the absence of clinical symptoms, the current study compared the effects of concussions on attentional capacities (reaction times, accuracy) and Event-Related Potentials (ERPs) in concussed athletes with (n = 10) or without (n = 10) symptoms as well as in athletes who never had a concussion (n = 10). The P300 response was recorded from 28 electrodes during a modified visual oddball paradigm. Participants were instructed to press a key upon the appearance of the frequent stimuli as well as when a rare nontarget stimulus followed the frequent one. The other key was to be pressed when the subsequent rare stimuli (rare target) appeared until a frequent one reappeared. The symptomatic athletes displayed longer reaction times than the other two groups of athletes. The P300 amplitude to the rare target stimuli was significantly more attenuated in the symptomatic athletes than in the other two groups. Moreover, the P300 amplitude varied inversely with the severity of post-concussion symptoms but was not influenced by time elapsed since injury. Although the clinical significance of the P300 differences shown by the symptomatic athletes is still uncertain, the results do indicate that symptom severity may be a crucial indicator of functional impairments following mild traumatic brain injury.

Regardless of the level of risk-taking, expectancy of winning is a cognitive factor influencing levels of arousal. When playing for fun, gambling becomes significantly less stimulating than when playing for money.

Visually challenged individuals often compensate for their handicap by developing supra-normal abilities in their remaining sensory systems. Here, we examined the scalp distribution of components N1 and P3 of auditory evoked potentials during a sound localization task in four totally blind subjects who had previously shown better performance than sighted subjects. Both N1 and P3 waves peaked at their usual positions while blind and sighted individuals performed the task. However, in blind subjects these two components were also found to be robust over occipital regions while in sighted individuals this pattern was not seen. We conclude that deafferented posterior visual areas in blind individuals are recruited to carry out auditory functions, enabling these individuals to compensate for their lack of vision.

Prevalence, symptoms, and treatment of depression suggest that major depressive disorders (MDD) present sex differences. Social stress-induced neurovascular pathology is associated with depressive symptoms in male mice; however, this association is unclear in females. Here, we report that chronic social and subchronic variable stress promotes blood-brain barrier (BBB) alterations in mood-related brain regions of female mice. Targeted disruption of the BBB in the female prefrontal cortex (PFC) induces anxiety- and depression-like behaviours. By comparing the endothelium cell-specific transcriptomic profiling of the mouse male and female PFC, we identify several pathways and genes involved in maladaptive stress responses and resilience to stress. Furthermore, we confirm that the BBB in the PFC of stressed female mice is leaky. Then, we identify circulating vascular biomarkers of chronic stress, such as soluble E-selectin. Similar changes in circulating soluble E-selectin, BBB gene expression and morphology can be found in blood serum and postmortem brain samples from women diagnosed with MDD. Altogether, we propose that BBB dysfunction plays an important role in modulating stress responses in female mice and possibly MDD.

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