@article {47463, title = {Brain derived neurotrophic factor differentially modulates excitability of two classes of hippocampal output neurons.}, journal = {Journal of Neurophysiology}, volume = {116}, year = {2016}, month = {2016 May 4}, pages = {466-71}, abstract = {

Brain-derived neurotrophic factor (BDNF) plays an important role in hippocampus-dependent learning and memory. Canonically, this has been ascribed to an enhancing effect on neuronal excitability and synaptic plasticity in the CA1 region. However, it is the pyramidal neurons in the subiculum that form the primary efferent pathways conveying hippocampal information to other areas of the brain, and yet the effect of BDNF on these neurons has remained unexplored. We present new data that BDNF regulates neuronal excitability and cellular plasticity in a much more complex manner than previously suggested. Subicular pyramidal neurons can be divided into two major classes, which have different electrophysiological and morphological properties, different requirements for the induction of plasticity and different extra-hippocampal projections. We found that BDNF increases excitability in one class of subicular pyramidal neurons, yet decreases excitability of the other class. Further, while endogenous BDNF was necessary for the induction of synaptic plasticity in both cell types, BDNF enhanced intrinsic plasticity in one class of pyramidal neurons, yet suppressed intrinsic plasticity in the other. Taken together, these data suggest a novel role for BDNF signaling, as it appears to dynamically and bidirectionally regulate the output of hippocampal information to different regions of the brain.

}, issn = {1522-1598}, doi = {10.1152/jn.00186.2016}, author = {Graves, Austin R and Moore, Shannon J and Spruston, Nelson and Tryba, Andrew Kieran and Kaczorowski, Catherine C} } @article {6720, title = {Hippocampal pyramidal neurons comprise two distinct cell types that are countermodulated by metabotropic receptors.}, journal = {Neuron}, volume = {76}, year = {2012}, month = {2012 Nov 21}, pages = {776-89}, abstract = {

Relating the function of neuronal cell types to information processing and behavior is a central goal of neuroscience. In the hippocampus, pyramidal cells in CA1 and the subiculum process sensory and motor cues to form a cognitive map encoding spatial, contextual, and emotional information, which they transmit throughout the brain. Do these cells constitute a single class or are there multiple cell types with specialized functions? Using unbiased cluster analysis, we show that there are two morphologically and electrophysiologically distinct principal cell types that carry hippocampal output. We show further that these two cell types are inversely modulated by the synergistic action of glutamate and acetylcholine acting on metabotropic receptors that are central to hippocampal function. Combined with prior connectivity studies, our results support a model of hippocampal processing in which the two pyramidal cell types are predominantly segregated into two parallel pathways that process distinct modalities of information.

}, keywords = {3-dione, 6-Cyano-7-nitroquinoxaline-2, Analysis of Variance, Animals, Benzylamines, Biophysics, CA1 Region, Electric Stimulation, Excitatory Amino Acid Antagonists, Excitatory Amino Acid Transporter 3, GABA Antagonists, Glutamate Decarboxylase, Hippocampal, Lysine, Male, Membrane Potentials, Metabotropic Glutamate, Neurons, Newborn, Patch-Clamp Techniques, Phosphinic Acids, Pyridazines, Rats, Receptors, Time Factors}, issn = {1097-4199}, doi = {10.1016/j.neuron.2012.09.036}, author = {Graves, Austin R and Moore, Shannon J and Bloss, Erik B and Mensh, Brett D and Kath, William L and Spruston, Nelson} } @article {45911, title = {Plasticity of burst firing induced by synergistic activation of metabotropic glutamate and acetylcholine receptors.}, journal = {Neuron}, volume = {61}, year = {2009}, month = {2009 Jan 29}, pages = {287-300}, abstract = {

Subiculum, the primary efferent pathway of hippocampus, participates in memory for spatial tasks, relapse to drug abuse, and temporal lobe seizures. Subicular pyramidal neurons exhibit low-threshold burst firing driven by a spike afterdepolarization. Here we report that burst firing can be regulated by stimulation of afferent projections to subiculum. Unlike synaptic plasticity, burst plasticity did not require synaptic depolarization, activation of AMPA or NMDA receptors, or action potential firing. Rather, enhancement of burst firing required synergistic activation of group I, subtype 1 metabotropic glutamate receptors (mGluRs) and muscarinic acetylcholine receptors (mAChR). When either of these receptors was blocked, a suppression of bursting was revealed, which in turn was blocked by antagonists of group I, subtype 5 mGluRs. These results indicate that the output of subiculum can be strongly and bidirectionally regulated by activation of glutamatergic inputs within the hippocampus and cholinergic afferents from the medial septum.

}, keywords = {Acetylcholine, Action Potentials, Afferent Pathways, Animals, Cholinergic Fibers, Electric Stimulation, Excitatory Amino Acid Antagonists, Glutamic Acid, Hippocampus, Male, Neuronal Plasticity, Pyramidal Cells, Rats, Rats, Wistar, Receptors, Cholinergic, Receptors, Metabotropic Glutamate, Receptors, Muscarinic, Septal Nuclei, Synaptic Transmission, Theta Rhythm}, issn = {1097-4199}, doi = {10.1016/j.neuron.2008.12.013}, author = {Moore, Shannon J and Cooper, Donald C and Spruston, Nelson} }