Spatial and Working Memory Is Linked to Spine Density and Mushroom Spines

Abstract

BackgroundChanges in synaptic structure and efficacy including dendritic spine number and morphology have been shown to underlie neuronal activity and size. Moreover, the shapes of individual dendritic spines were proposed to correlate with their capacity for structural change. Spine numbers and morphology were reported to parallel memory formation in the rat using a water maze but, so far, there is no information on spine counts or shape in the radial arm maze (RAM), a frequently used paradigm for the evaluation of complex memory formation in the rodent.Methods24 male Sprague-Dawley rats were divided into three groups, 8 were trained, 8 remained untrained in the RAM and 8 rats served as cage controls. Dendritic spine numbers and individual spine forms were counted in CA1, CA3 areas and dentate gyrus of hippocampus using a DIL dye method with subsequent quantification by the Neuronstudio software and the image J program.ResultsWorking memory errors (WME) and latency in the RAM were decreased along the training period indicating that animals performed the task. Total spine density was significantly increased following training in the RAM as compared to untrained rats and cage controls. The number of mushroom spines was significantly increased in the trained as compared to untrained and cage controls. Negative significant correlations between spine density and WME were observed in CA1 basal dendrites and in CA3 apical and basal dendrites. In addition, there was a significant negative correlation between spine density and latency in CA3 basal dendrites.ConclusionThe study shows that spine numbers are significantly increased in the trained group, an observation that may suggest the use of this method representing a morphological parameter for memory formation studies in the RAM. Herein, correlations between WME and latency in the RAM and spine density revealed a link between spine numbers and performance in the RAM.

The pseudokinase CaMKv is required for the activity-dependent maintenance of dendritic spines

“…Emerging evidence suggests that hippocampus contributes to spatial encoding in working memory through synaptic changes3233. We therefore also determined whether CaMKv is involved in the processing of working memory.…”

GSK3β Hyperactivity during an Early Critical Period Impairs Prefrontal Synaptic Plasticity and Induces Lasting Deficits in Spine Morphology and Working Memory

“…Although the exact functional correlates of spine morphology remain unknown, mushroom spine represents functional maturation of synaptic connection (Sala et al, 2014). Studies have also implicated mushroom spines in memory (Bourne and Harris, 2007;Matsuo et al, 2008), and indeed, spatial and working memory is linked to spine density and mushroom spines (Mahmmoud et al, 2015). The reduction of mushroom spines in adult SAL-SB rats could thus explain the working memory impairment although how brief exposure of GSK3 inhibitor during early postnatal development leads to long-lasting disruption of spine maturation remains to be determined.…”

Influence of postnatal glucocorticoids on hippocampal-dependent learning varies with elevation patterns and administration methods

“…The hippocampus is rich with glucocorticoid receptors and plays a pivotal role in regulation of the stress response by providing negative feedback to the hypothalamic-pituitary- adrenal (HPA) system. In addition, the hippocampus is a critical structure for learning and memory including short-term memory storage, the formation of new memories, and spatial working memory (Eichenbaum et al, 2016; Mahmmoud et al, 2015; Garcia, 2001). Some glucocorticoid activation is necessary for memory formation, and acute elevations can increase hippocampal LTP to promote learning (Beylin & Shors, 2003; Blank et al, 2002).…”