Commentary Cellscience Reviews Vol 4 No 1 ISSN 1742-8130

LTD in cerebellar Purkinje cells: what do spines have to do with it?

Current research in the field of synaptic plasticity suggests that there is a correlation between morphological changes observed in dendritic spines and concomitant electrophysiological changes observed in neurons. However, there is much controversy about how closely morphology and electrophysiology are correlated. In a recent issue of Nature Neuroscience, Andrei Sdrulla and David Linden report no observable change in the size of dendritic spines on Purkinje cells (PCs) after the chemical and electrophysiological induction of long-term depression (LTD). These results conflict with previous studies conducted in hippocampal pyramidal cell spines that found spine retraction and/or reduction in spine volume after LTD induction (Nägerl, 2004; Zhou, 2004). Furthermore, spine retraction can be induced in PCs without altering synaptic transmission. The results from Linden’s lab add to the list of differences between pyramidal cell spines and Purkinje cell spines, and may highlight important differences in the signaling pathways downstream of the different subset of glutamate receptors at the synapses of each cell type. Importantly, however, the results indicate that changes in synaptic efficacy do not necessarily result in morphological changes, at least not in all cell types.

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