Stably maintained dendritic spines are associated with lifelong memories

Abstract

Changes in synaptic connections are considered essential for learning and memory formation1–6. However, it is unknown how neural circuits undergo continuous synaptic changes during learning while maintaining lifelong memories. Here we show, by following postsynaptic dendritic spines over time in the mouse cortex7–8, that learning and novel sensory experience lead to spine formation and elimination by a protracted process. The extent of spine remodelling correlates with behavioural improvement after learning, suggesting a crucial role of synaptic structural plasticity in memory formation and storage. Importantly, a small fraction of new spines induced by novel experience, together with most spines formed early during development and surviving experience-dependent elimination, are preserved throughout the entire life of an animal. These studies indicate that learning and daily sensory experience leave minute but permanent marks on cortical connections and suggest that lifelong memories are stored in largely stably connected synaptic networks.

Dendritic spine actin cytoskeleton in autism spectrum disorder

“…The majority of excitatory glutamatergic synapses are located in small dendritic protrusions known as spines. The formation, maturation and elimination of dendritic spines lie at the core of synaptic transmission and memory formation 11,12 .…”

Time scales of memory, learning, and plasticity

“…Changes during long-term-memory experiments are found in a distributed cortical network (Frankland et al 2001(Frankland et al , 2004, however, mainly in the prefrontal cortex (Frankland and Bontempi 2005). Those changes happen through synaptic and structural plasticity (Frankland and Bontempi 2005;Xu et al 2009;Yang et al 2009;Ziv and Ahissar 2009). Although the time scale of long-term memory could be up to "infinity," it is still under debate how items can be stored for such a long time (Frankland and Bontempi 2005).…”

“…As proposed by (Päpper et al 2011), long-term plasticity, together with synaptic tagging, could form cell assemblies that pass through synaptic consolidation from a fragile to a more stable state. (7) Long-term memory-structural plasticity (experimental) When rats experience enriched environments, their dendrites start to build significantly more spines than in a control environment (Xu et al 2009;Yang et al 2009). …”

Vers une explication des effets mnémoniques des glucocorticoïdes ?

“…Ces effets sont exprimés sous la forme caractéristique de courbe inversée, car seule une concentration optimale de glucocorticoïde, introduite au bon moment, produit une plasticité maximale. Des [1]. Comme interfaces fonctionnelles entre les neurones, les synapses sont impliquées dans l'assemblage des réseaux neuronaux et l'intégration de l'information.…”