Actin cytoskeleton: the backbone of memory trace?

MEDINA, CANDELA; DE LA FUENTE, VERÓNICA; ROMANO, ARTURO

Mar del Plata, Buenos Aires

Congreso; XXXII Congreso Anual de la Sociedad Argentina de Investigación en Neurociencias; 2017

Sociedad Argentina de Investigación en Neurociencias

Long-term memory has been associated with morphological changes in the brain, in strict correlation with changes in synaptic efficacy. Such plasticity is proposed to rely on dendritic spines as a sort of neuronal canvas on which these changes can take place. Given its key role on spine morphology, actin cytoskeleton dynamics and its major regulating factors (such as ADF/Cofilin) become an attractive target to study processes underlying dendritic plasticity. Using a contextual fear conditioning paradigm in mice, we found that pharmacological induction of depolymerization of actin filaments through an intra-hippocampal injection of BMS-5 ?a potent inhibitor of LIM kinase, which is in turn an inhibitor of ADF/Cofilin activity? causes an impairment in memory consolidation and reconsolidation. On the other hand, when favoring stabilization of actin filaments by intra-hippocampal injection of Jasplakinolide immediately before reminder session that usually elicits reconsolidation of memory, we found that the consolidation of an extinction memory was facilitated. On top of that, a synaptoneurosome-enriched hippocampal extraction shortly after reminder session showed an increased P-Cofilin/Cofilin ratio, implying a diminished depolymerization activity by this factor, therefore favoring stabilization of actin filaments. All of these results support the role of actin cytoskeleton dynamics in the morphological changes which underlie the ?memory trace?.