Neuroscience
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Spontaneous and visual stimulation evoked firing sequences are distinct under desflurane anesthesia.
Recurring spike sequences are thought to underlie cortical computations and may be essential for information processing in the conscious state. How anesthesia at graded levels may influence spontaneous and stimulus-related spike sequences in visual cortex has not been fully elucidated. We recorded extracellular single-unit activity in the rat primary visual cortex in vivo during wakefulness and three levels of anesthesia produced by desflurane. ⋯ Flash-evoked spike sequences showed higher reliability and longer latency when stimuli were applied during DOWN states compared to UP states. At deeper levels, desflurane altered both UP state and flash-evoked spike sequences by selectively suppressing inhibitory neuron firing. The results reveal desflurane-induced complex changes in cortical firing sequences that may influence visual information processing.
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Altered reward processing is increasingly recognised as a crucial mechanism underpinning apathy in many brain disorders. However despite its clinical relevance, little is known about the mechanisms of apathy following moderate-to-severe traumatic brain injury (TBI). In real-life situations, reward representations encompass both foreground (gains from current activity) and background (potential gains from the broader environment) elements. This latter variable provides a crucial set-point for switching behaviour in many naturalistic settings. We hypothesised apathy post-TBI would be associated with disrupted background reward sensitivity. ⋯ These results provide the first evidence directly linking disrupted background reward processing to apathy in any brain disorder. They identify a novel mechanism for apathy following moderate-to-severe TBI, and point towards novel interventions to improve this debilitating complication of head injury.
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There is a growing interest for studying the impact of chronic inflammation, particularly lung inflammation, on the brain and behavior. This includes asthma, a chronic inflammatory condition, that has been associated with psychiatric conditions such as posttraumatic stress disorder (PTSD). Although asthma is driven by elevated production of Th2 cytokines (IL-4, IL-5 and IL-13), which drive asthma symptomology, recent work demonstrates that concomitant Th1 or Th17 cytokine production can worsen asthma severity. ⋯ While HDM evoked a Th2-skewed immune response in lung tissue, no significant alterations in brain Th cell subsets were observed. Significantly reduced ΔFosB+ cells in the basolateral amygdala of HDM mice were observed post extinction. Our data indicate that allergen-driven Th2-skewed responses may induce fear extinction promoting effects, highlighting beneficial interactions of Th2-associated immune mediators with fear regulatory circuits.
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The glymphatic system is important for waste removal in the central nervous system. It removes soluble proteins and metabolic waste under the action of aquaporin-4 (AQP4) at the end of astrocytes. The glymphatic system plays a role in numerous neurological diseases; however, the relationship between migraine and the glymphatic system remains unclear. ⋯ Then, further suppression of glymphatic function by TGN-020 (an AQP4 blocker) aggravated the migraine pathological changes in mice. The results indicated that glymphatic dysfunction may aggravate migraine pathology. Therefore, our findings revealed the potential role of the glymphatic system in migraine, providing possible targets for migraine prevention and treatment.