Clustered Loss of Dendritic Spines Characterizes Encoding of Related Memory

Generation of new spines is often thought of as a correlate of memory and loss of spines is considered representing memory loss. Contrary to common belief, we observe that spine loss has functional value in distinctly encoding related life events rather than causing memory loss. Using spatial autocorrelation of dendritic morphology obtained from in vivo longitudinal imaging, we show that clustered loss, rather than gain, of new spines characterizes the formation of related memory. This spatially selective dendritic spine loss occurs closer to new spines formed during the acquisition of initial memory. Thus, enabling the dendrites to store multiple memories and their inter relationship. Remarkably, we find acquisition of related memory in the absence of NMDAR activation increases the fraction of such correlated spine loss.