GABAergic interneurons with nonlinear dendrites: from neuronal computations to memory engrams

GABAergic interneurons are a highly diverse class of neurons in the mammalian brain with a critical role in orchestrating multiple cognitive functions and maintaining the balance of excitation/ inhibition across neuronal circuitries. In this perspective, we discuss recent findings regarding the ability of some interneuron subtypes to integrate incoming inputs in nonlinear ways within their dendritic branches. These recently discovered features may endow the specific interneurons with advanced computing capabilities, whose breadth and functional contributions remain an open question. Along these lines, we discuss theoretical and experimental evidence regarding the potential role of nonlinear interneuron dendrites in advancing single neuron computations and contributing to memory formation

Hotspots of dendritic spine turnover facilitate clustered spine addition and learning and memory

Structural remodeling of dendritic spines is thought to be a mechanism of memory storage. Here, the authors look at how spine turnover and clustering predict future learning and memory performance, and see that a genetically modified mouse with enhanced spine turnover has enhanced learning

Antidepressants influence somatostatin levels and receptor pharmacology in brain

This study investigated how the administration (acute and chronic) of the antidepressants citalopram and desmethylimipramine (DMI) influences somatostatin (somatotropin release inhibitory factor, SRIF) levels and SRIF receptor density (sst1-5) in rat brain. Animals received either of the following treatments: (1) saline for 21 days (control group), (2) saline for 20 days and citalopram or DMI for 1 day (citalopram or DMI acute groups), (3) citalopram or DMI for 21 days (citalopram or DMI chronic groups). Somatostatin levels were determined by radioimmunoassay. [125I]LTT SRIF-28 binding in the absence (labeling of sst1-5) or presence of 3 nM MK678 (labeling of sst1/4) and [125I]Tyr3 octreotide (labeling of sst2/5) binding with subsequent autoradiography was performed in brains of rats treated with both antidepressants. Somatostatin levels were increased after citalopram, but not DMI administration, in the caudate-putamen, hippocampus, nucleus accumbens, and prefrontal cortex. Autoradiography studies illustrated a significant decrease in receptor density in the superficial and deep layers of frontal cortex (sst2), as well as a significant increase in the CA1 (sst1/4) hippocampal field in brains of chronically citalopram-treated animals. DMI administration increased sst 1/4 receptors levels in the CA1 hippocampal region. These results suggest that citalopram and to a lesser extent DMI influence the function of the somatostatin system in brain regions involved in the emotional, motivational, and cognitive aspects of behavior. © 2009 Nature Publishing Group All rights reserved