This competition was

also observed when we induced L-LTP under 1 mM Mg+2 conditions using multispine stimulation. Additionally, we found that only a fraction (approximately 25%) of stimulated spines expressed L-LTP. These data suggest that the amount of protein produced by such stimuli is limiting, and thus, the temporal and spatial constraints of STC that we discovered are likely to be similar between the cases where L-LTP was induced by single-spine stimulation and where it was induced by multiple spine stimulation. Synapses that participate in a long-term memory engram will arise not only from spines at which L-LTP was induced but also from spines at which E-LTP was originally induced via STC. However, it FLT3 inhibitor is essential that the spines at which E-LTP was induced be in close spatial proximity to the spines at which L-LTP was induced, preferably within the same dendritic branch. The branch bias of L-LTP induction found in our multispine stimulation experiments conducted Buparlisib manufacturer under 1 mM Mg+2 conditions implies that L-LTP induction will preferentially occur within distinct dendritic branches, and not throughout the dendritic arbor. These dendritic branch biases for the induction and expression of L-LTP would

result in a preferential spatial clustering within dendritic branches of synapses that would participate in a long-term memory engram. This clustering effect would be enhanced by the competitive nature of L-LTP induction and STC, as capture

of protein by synapses near the location of the L-LTP induction would result in less protein available to synapses farther away. If L-LTP induction requires the participating synapses to be within a limited dendritic distance Megestrol Acetate within the branch, a hypothesis that we were unable to test for technical reasons, then it remains possible that the integrative unit for a long-term memory engram is a subregion of a dendritic branch, and not the entire branch. These data suggest that at the single-cell level, hippocampal CA1 cells store long-term memory engrams at synapses that tend to be clustered within dendritic branches as opposed to dispersed throughout the dendritic arbor (Govindarajan et al., 2006). Storing long-term memory engrams in a clustered fashion has advantages over storing them in a dispersed fashion because it would facilitate the formation of memories and increase the ability for memories to be recalled, due to the ability of synaptic inputs arriving at a branch to supralinearly summate in depolarizing the cell (Gasparini and Magee, 2006, Gasparini et al., 2004, Govindarajan et al., 2006, Poirazi et al., 2003a, Poirazi et al., 2003b and Poirazi and Mel, 2001). In addition, this supralinear summation (Gasparini and Magee, 2006, Gasparini et al., 2004, Poirazi et al.