The plasticity mechanisms in the nervous system that are important for learning and memory are greatly impacted during aging. Notably, hippocampal-dependent long-term plasticity and its associative plasticity, such as synaptic tagging and capture (STC), show considerable age-related decline. The p75 neurotrophin receptor (p75 ) is a negative regulator of structural and functional plasticity in the brain and thus represents a potential candidate to mediate age-related alterations. However, the mechanisms by which p75 affects synaptic plasticity of aged neuronal networks and ultimately contribute to deficits in cognitive function have not been well characterized. Here, we report that mutant mice lacking the p75 were resistant to age-associated changes in long-term plasticity, associative plasticity, and associative memory. Our study shows that p75 is responsible for age-dependent disruption of hippocampal homeostatic plasticity by modulating several signaling pathways, including BDNF, MAPK, Arc, and RhoA-ROCK2-LIMK1-cofilin. p75 may thus represent an important therapeutic target for limiting the age-related memory and cognitive function deficits.
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http://dx.doi.org/10.1111/acel.13305 | DOI Listing |
Sci Rep
December 2024
BioMag Laboratory, HUS Diagnostic Center, Helsinki University Hospital, University of Helsinki and Aalto University School of Science, Helsinki, Finland.
A novel variant of paired-associative stimulation (PAS) consisting of high-frequency peripheral nerve stimulation (PNS) and high-intensity transcranial magnetic stimulation (TMS) above the motor cortex, called high-PAS, can lead to improved motor function in patients with incomplete spinal cord injury. In PAS, the interstimulus interval (ISI) between the PNS and TMS pulses plays a significant role in the location of the intended effect of the induced plastic changes. While conventional PAS protocols (single TMS pulse often applied with intensity close to resting motor threshold, and single PNS pulse) usually require precisely defined ISIs, high-PAS can induce plasticity at a wide range of ISIs and also in spite of small ISI errors, which is helpful in clinical settings where precise ISI determination can be challenging.
View Article and Find Full Text PDFbioRxiv
December 2024
Cerebral Codes and Circuits Connectivity team, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University; Paris, France.
How are associative memories formed? Which cells represent a memory, and when are they engaged? By visualizing and tagging cells based on their calcium influx with unparalleled temporal precision, we identified non-overlapping dorsal CA1 neuronal ensembles that are differentially active during associative fear memory acquisition. We dissected the acquisition experience into periods during which salient stimuli were presented or certain mouse behaviors occurred and found that cells associated with specific acquisition periods are sufficient alone to drive memory expression and contribute to fear engram formation. This study delineated the different identities of the cell ensembles active during learning, and revealed, for the first time, which ones form the core engram and are essential for memory formation and recall.
View Article and Find Full Text PDFBrain Commun
December 2024
Engineering Research Center of Traditional Chinese Medicine Intelligent Rehabilitation, Ministry of Education, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
The cortico-cortical paired associative stimulation, a combined stimulation based on two brain regions, may be an effective strategy for stroke rehabilitation. Our aim was to confirm that the cortico-cortical paired associative stimulation strengthens the connection between brain regions in the motor circuit and promotes improvements in motor function. This was a randomized double-blind, controlled Phase II trial.
View Article and Find Full Text PDFMol Brain
December 2024
Department of Neurosciences, University of New Mexico School of Medicine, 915 Camino de Salud NE, Fitz Hall 145, Albuquerque, NM, 87131, USA.
The vast majority of gene mutations and/or gene knockouts result in either no observable changes, or significant deficits in molecular, cellular, or organismal function. However, in a small number of cases, mutant animal models display enhancements in specific behaviors such as learning and memory. To date, most gene deletions shown to enhance cognitive ability generally affect a limited number of pathways such as NMDA receptor- and translation-dependent plasticity, or GABA receptor- and potassium channel-mediated inhibition.
View Article and Find Full Text PDFAssociative plasticity at thalamocortical synapses is thought to be constrained by age in the mammalian cortex. However, here we show for the first time that prolonged visual deprivation induces robust and reversible plasticity at synapses between first order visual thalamus and cortical layer 4 pyramidal neurons. The plasticity is associative and expressed by changes in presynaptic function, thereby amplifying and relaying the change in efferent drive to the visual cortex.
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