@article {46744, title = {Visualization and neuronal cell targeting during electrophysiological recordings facilitated by quantum dots.}, journal = {Proceedings of SPIE}, volume = {9305}, year = {2015}, month = {2015 Mar 10}, pages = {9305Y}, abstract = {

The simultaneous visualization, identification and targeting of neurons during patch clamp-mediated electrophysiological recordings is a basic technique in neuroscience, yet it is often complicated by the inability to visualize the pipette tip, particularly in deep brain tissue. Here we demonstrate a novel approach in which fluorescent quantum dot probes are used to coat pipettes prior to their use. The strong two-photon absorption cross sections of the quantum dots afford robust contrast at significantly deeper penetration depths than current methods allow. We demonstrate the utility of this technique in multiple recording formats both in vitro and in vivo where imaging of the pipettes is achieved at remarkable depths (up to 800 microns). Notably, minimal perturbation of cellular physiology is observed over the hours-long time course of neuronal recordings. We discuss our results within the context of the role that quantum dot nanoprobes may play in understanding neuronal cell physiology.

}, doi = {10.1117/12.2076934}, author = {Field, Lauren D and Andrasfalvy, Bertalan K and Gali{\~n}anes, Gregorio L and Huber, Daniel and Barbic, Mladen and Macklin, John J and Susumu, Kimihiro and Delehanty, James B and Huston, Alan L and Makara, Judit K and Medintz, Igor L} } @article {45812, title = {Quantum dot-based multiphoton fluorescent pipettes for targeted neuronal electrophysiology.}, journal = {Nature Methods}, volume = {11}, year = {2014}, month = {2014 Dec}, pages = {1237-41}, abstract = {

Targeting visually identified neurons for electrophysiological recording is a fundamental neuroscience technique; however, its potential is hampered by poor visualization of pipette tips in deep brain tissue. We describe quantum dot-coated glass pipettes that provide strong two-photon contrast at deeper penetration depths than those achievable with current methods. We demonstrated the pipettes{\textquoteright} utility in targeted patch-clamp recording experiments and single-cell electroporation of identified rat and mouse neurons in vitro and in vivo.

}, issn = {1548-7105}, doi = {10.1038/nmeth.3146}, author = {Andrasfalvy, Bertalan K and Gali{\~n}anes, Gregorio L and Huber, Daniel and Barbic, Mladen and Macklin, John J and Susumu, Kimihiro and Delehanty, James B and Huston, Alan L and Makara, Judit K and Medintz, Igor L} } @article {6888, title = {Variable dendritic integration in hippocampal CA3 pyramidal neurons.}, journal = {Neuron}, volume = {80}, year = {2013}, month = {2013 Dec 18}, pages = {1438-50}, abstract = {

The hippocampal CA3 region is essential for pattern completion and generation of sharp-wave ripples. During these operations, coordinated activation of ensembles of CA3 pyramidal neurons produces spatiotemporally structured input patterns arriving onto dendrites of recurrently connected CA3 neurons. To understand how such input patterns are translated into specific output patterns, we characterized dendritic integration in CA3 pyramidal cells using two-photon imaging and glutamate uncaging. We found that thin dendrites of CA3 pyramidal neurons integrate synchronous synaptic input in a highly supralinear fashion. The amplification was primarily mediated by NMDA receptor activation and was present over a relatively broad range of spatiotemporal input patterns. The decay of voltage responses, temporal summation, and action potential output was regulated in a compartmentalized fashion mainly by a G-protein-activated inwardly rectifying K(+) current. Our results suggest that plastic dendritic integrative\ mechanisms may support ensemble behavior in pyramidal neurons of the hippocampal circuitry.

}, keywords = {Action Potentials, Animals, CA3 Region, Dendrites, G Protein-Coupled Inwardly-Rectifying Potassium Channels, Glutamic Acid, Hippocampal, Male, N-Methylaspartate, Potassium Channels, Pyramidal Cells, Rats, Sodium}, issn = {1097-4199}, doi = {10.1016/j.neuron.2013.10.033}, author = {Makara, Judit K and Magee, Jeffrey C} } @article {5922, title = {Synaptic amplification by dendritic spines enhances input cooperativity.}, journal = {Nature}, volume = {491}, year = {2012}, month = {2012 Nov 22}, pages = {599-602}, abstract = {

Dendritic spines are the nearly ubiquitous site of excitatory synaptic input onto neurons and as such are critically positioned to influence diverse aspects of neuronal signalling. Decades of theoretical studies have proposed that spines may function as highly effective and modifiable chemical and electrical compartments that regulate synaptic efficacy, integration and plasticity. Experimental studies have confirmed activity-dependent structural dynamics and biochemical compartmentalization by spines. However, there is a longstanding debate over the influence of spines on the electrical aspects of synaptic transmission and dendritic operation. Here we measure the amplitude ratio of spine head to parent dendrite voltage across a range of dendritic compartments and calculate the associated spine neck resistance (R(neck)) for spines at apical trunk dendrites in rat hippocampal CA1 pyramidal neurons. We find that R(neck) is large enough (\ 500 MΩ) to amplify substantially the spine head depolarization associated with a unitary synaptic input by \ 1.5- to \ 45-fold, depending on parent dendritic impedance. A morphologically realistic compartmental model capable of reproducing the observed spatial profile of the amplitude ratio indicates that spines provide a consistently high-impedance input structure throughout the dendritic arborization. Finally, we demonstrate that the amplification produced by spines encourages electrical interaction among coactive inputs through an R(neck)-dependent increase in spine head voltage-gated conductance activation. We conclude that the electrical properties of spines promote nonlinear dendritic processing and associated forms of plasticity and storage, thus fundamentally enhancing the computational capabilities of neurons.

}, keywords = {Animals, Dendritic Spines, Electric Impedance, Excitatory Postsynaptic Potentials, Male, Models, Neurological, Pyramidal Cells, Rats, Sprague-Dawley, Synapses, Wistar}, issn = {1476-4687}, doi = {10.1038/nature11554}, author = {Harnett, Mark T and Makara, Judit K and Spruston, Nelson and Kath, William L and Magee, Jeffrey C} } @article {2122, title = {Experience-dependent compartmentalized dendritic plasticity in rat hippocampal CA1 pyramidal neurons.}, journal = {Nature Neuroscience}, volume = {12}, year = {2009}, month = {2009 Dec}, pages = {1485-7}, abstract = {

The excitability of individual dendritic branches is a plastic property of neurons. We found that experience in an enriched environment increased propagation of dendritic Na(+) spikes in a subset of individual dendritic branches in rat hippocampal CA1 pyramidal neurons and that this effect was mainly mediated by localized downregulation of A-type K(+) channel function. Thus, dendritic plasticity might be used to store recent experience in individual branches of the dendritic arbor.

}, keywords = {Action Potentials, Animals, CA1 Region, Dendrites, Down-Regulation, Environment, Hippocampal, Memory, Neuronal Plasticity, Potassium Channels, Pyramidal Cells, Rats}, issn = {1546-1726}, doi = {10.1038/nn.2428}, author = {Makara, Judit K and Losonczy, Attila and Wen, Quan and Magee, Jeffrey C} } @article {3915, title = {Compartmentalized dendritic plasticity and input feature storage in neurons.}, journal = {Nature}, volume = {452}, year = {2008}, month = {2008 Mar 27}, pages = {436-41}, abstract = {

Although information storage in the central nervous system is thought to be primarily mediated by various forms of synaptic plasticity, other mechanisms, such as modifications in membrane excitability, are available. Local dendritic spikes are nonlinear voltage events that are initiated within dendritic branches by spatially clustered and temporally synchronous synaptic input. That local spikes selectively respond only to appropriately correlated input allows them to function as input feature detectors and potentially as powerful information storage mechanisms. However, it is currently unknown whether any effective form of local dendritic spike plasticity exists. Here we show that the coupling between local dendritic spikes and the soma of rat hippocampal CA1 pyramidal neurons can be modified in a branch-specific manner through an N-methyl-d-aspartate receptor (NMDAR)-dependent regulation of dendritic Kv4.2 potassium channels. These data suggest that compartmentalized changes in branch excitability could store multiple complex features of synaptic input, such as their spatio-temporal correlation. We propose that this {\textquoteright}branch strength potentiation{\textquoteright} represents a previously unknown form of information storage that is distinct from that produced by changes in synaptic efficacy both at the mechanistic level and in the type of information stored.

}, keywords = {Action Potentials, Animals, Cell Shape, Dendrites, Ion Channel Gating, Male, Mice, Models, N-Methyl-D-Aspartate, Neurological, Neuronal Plasticity, Pyramidal Cells, Rats, Receptors, Shal Potassium Channels, Sprague-Dawley}, issn = {1476-4687}, doi = {10.1038/nature06725}, author = {Losonczy, Attila and Makara, Judit K and Magee, Jeffrey C} }