[Neurology : what's new in 2021]. / Neurologie.

In 2021, we assisted to the publication of new diagnostic criteria, classifications, and guidelines (CIDP, brain tumors, auto-immune encephalitis). Several studies helped to define the pharmacological management of focal and generalized epileptic seizures and epilepsy in pregnant women. The availability of biomarkers and the approval of immunotherapies are modifying the landscape of dementia management. Endovascular interventions without previous thrombolysis seems to be effective in anterior circulation acute ischemic stroke (AIS) and severe posterior circulation AIS. Neurologic complications of Sars-CoV-2 infection were further studied, as well as the efficacy of vaccines in immunosuppressed patients. New molecules and techniques show promising results for the treatment of migraine and cluster headache.

L'année 2021 a été marquée par la publication des nouveaux critères diagnostiques, classifications et guidelines (polyradiculonévrite inflammatoire démyélinisante chronique, tumeurs cérébrales, encéphalites autoimmunes). L'attitude thérapeutique dans les épilepsies focales ou généralisées et l'épilepsie chez la femme enceinte a été mieux définie. Les marqueurs biologiques et les immunothérapies modifient le paysage de la prise en charge des démences. Le traitement endovasculaire des AVC de la circulation antérieure semble efficace indépendamment d'une thrombolyse préalable, ainsi qu'en cas d'AVC sévère de la circulation postérieure. Les complications neurologiques du SARS-CoV-2 ont été éclaircies et l'efficacité des vaccins étudiée chez les patients immunosupprimés. Plusieurs nouvelles molécules et techniques montrent des résultats prometteurs pour les migraines et céphalées en grappe.

How the visual brain encodes and keeps track of time.

Time is embedded in any sensory experience: the movements of a dance, the rhythm of a piece of music, the words of a speaker are all examples of temporally structured sensory events. In humans, if and how visual cortices perform temporal processing remains unclear. Here we show that both primary visual cortex (V1) and extrastriate area V5/MT are causally involved in encoding and keeping time in memory and that this involvement is independent from low-level visual processing. Most importantly we demonstrate that V1 and V5/MT come into play simultaneously and seem to be functionally linked during interval encoding, whereas they operate serially (V1 followed by V5/MT) and seem to be independent while maintaining temporal information in working memory. These data help to refine our knowledge of the functional properties of human visual cortex, highlighting the contribution and the temporal dynamics of V1 and V5/MT in the processing of the temporal aspects of visual information.

PKA phosphorylates and inactivates AMPKalpha to promote efficient lipolysis.

The mobilization of metabolic energy from adipocytes depends on a tightly regulated balance between hydrolysis and resynthesis of triacylglycerides (TAGs). Hydrolysis is stimulated by beta-adrenergic signalling to PKA that mediates phosphorylation of lipolytic enzymes, including hormone-sensitive lipase (HSL). TAG resynthesis is associated with high-energy consumption, which when inordinate, leads to increased AMPK activity that acts to restrain hydrolysis of TAGs by inhibiting PKA-mediated activation of HSL. Here, we report that in primary mouse adipocytes, PKA associates with and phosphorylates AMPKalpha1 at Ser-173 to impede threonine (Thr-172) phosphorylation and thus activation of AMPKalpha1 by LKB1 in response to lipolytic signals. Activation of AMPKalpha1 by LKB1 is also blocked by PKA-mediated phosphorylation of AMPKalpha1 in vitro. Functional analysis of an AMPKalpha1 species carrying a non-phosphorylatable mutation at Ser-173 revealed a critical function of this phosphorylation for efficient release of free fatty acids and glycerol in response to PKA-activating signals. These results suggest a new mechanism of negative regulation of AMPK activity by PKA that is important for converting a lipolytic signal into an effective lipolytic response.