@article {47974, title = {Layer 4 fast-spiking interneurons filter thalamocortical signals during active somatosensation.}, journal = {Nature Neuroscience}, volume = {19}, year = {2016}, month = {2016 Oct 17}, pages = {1647-57}, abstract = {

We rely on movement to explore the environment, for example, by palpating an object. In somatosensory cortex, activity related to movement of digits or whiskers is suppressed, which could facilitate detection of touch. Movement-related suppression is generally assumed to involve corollary discharges. Here we uncovered a thalamocortical mechanism in which cortical fast-spiking interneurons, driven by sensory input, suppress movement-related activity in layer 4 (L4) excitatory neurons. In mice locating objects with their whiskers, neurons in the ventral posteromedial nucleus (VPM) fired in response to touch and whisker movement. Cortical L4 fast-spiking interneurons inherited these responses from VPM. In contrast, L4 excitatory neurons responded mainly to touch. Optogenetic experiments revealed that fast-spiking interneurons reduced movement-related spiking in excitatory neurons, enhancing selectivity for touch-related information during active tactile sensation. These observations suggest a fundamental computation performed by the thalamocortical circuit to accentuate salient tactile information.

}, issn = {1546-1726}, doi = {10.1038/nn.4412}, author = {Yu, Jianing and Gutnisky, Diego A and Hires, S Andrew and Svoboda, Karel} } @article {6897, title = {Procedures for behavioral experiments in head-fixed mice.}, journal = {PLoS One}, volume = {9}, year = {2014}, month = {2014}, pages = {e88678}, abstract = {

The mouse is an increasingly prominent model for the analysis of mammalian neuronal circuits. Neural circuits ultimately have to be probed during behaviors that engage the circuits. Linking circuit dynamics to behavior requires precise control of sensory stimuli and measurement of body movements. Head-fixation has been used for behavioral research, particularly in non-human primates, to facilitate precise stimulus control, behavioral monitoring and neural recording. However, choice-based, perceptual decision tasks by head-fixed mice have only recently been introduced. Training mice relies on motivating mice using water restriction. Here we describe procedures for head-fixation, water restriction and behavioral training for head-fixed mice, with a focus on active, whisker-based tactile behaviors. In these experiments mice had restricted access to water (typically 1 ml/day). After ten days of water restriction, body weight stabilized at approximately 80\% of initial weight. At that point mice were trained to discriminate sensory stimuli using operant conditioning. Head-fixed mice reported stimuli by licking in go/no-go tasks and also using a forced choice paradigm using a dual lickport. In some cases mice learned to discriminate sensory stimuli in a few trials within the first behavioral session. Delay epochs lasting a second or more were used to separate sensation (e.g. tactile exploration) and action (i.e. licking). Mice performed a variety of perceptual decision tasks with high performance for hundreds of trials per behavioral session. Up to four months of continuous water restriction showed no adverse health effects. Behavioral performance correlated with the degree of water restriction, supporting the importance of controlling access to water. These behavioral paradigms can be combined with cellular resolution imaging, random access photostimulation, and whole cell recordings.

}, issn = {1932-6203}, doi = {10.1371/journal.pone.0088678}, author = {Guo, Zengcai V and Hires, S Andrew and Li, Nuo and O{\textquoteright}Connor, Daniel H and Komiyama, Takaki and Ophir, Eran and Huber, Daniel and Bonardi, Claudia and Morandell, Karin and Gutnisky, Diego and Peron, Simon and Xu, Ning-long and Cox, James and Svoboda, Karel} } @article {6158, title = {The mechanical variables underlying object localization along the axis of the whisker.}, journal = {The Journal of Neuroscience}, volume = {33}, year = {2013}, month = {2013 Apr 17}, pages = {6726-41}, abstract = {

Rodents move their whiskers to locate objects in space. Here we used psychophysical methods to show that head-fixed mice can localize objects along the axis of a single whisker, the radial dimension, with one-millimeter precision. High-speed videography allowed us to estimate the forces and bending moments at the base of the whisker, which underlie radial distance measurement. Mice judged radial object location based on multiple touches. Both the number of touches (1-17) and the forces exerted by the pole on the whisker (up to 573 μN; typical peak amplitude, 100 μN) varied greatly across trials. We manipulated the bending moment and lateral force pressing the whisker against the sides of the follicle and the axial force pushing the whisker into the follicle by varying the compliance of the object during behavior. The behavioral responses suggest that mice use multiple variables (bending moment, axial force, lateral force) to extract radial object localization. Characterization of whisker mechanics revealed that whisker bending stiffness decreases gradually with distance from the face over five orders of magnitude. As a result, the relative amplitudes of different stress variables change dramatically with radial object distance. Our data suggest that mice use distance-dependent whisker mechanics to estimate radial object location using an algorithm that does not rely on precise control of whisking, is robust to variability in whisker forces, and is independent of object compliance and object movement. More generally, our data imply that mice can measure the amplitudes of forces in the sensory follicles for tactile sensation.

}, keywords = {Algorithms, Animals, Biological, Computer Simulation, Corneal Topography, Cues, Decision Making, Electron, Exploratory Behavior, Functional Laterality, Inbred C57BL, Male, Mice, Microscopy, Models, Physical Stimulation, Psychophysics, Scanning, Time Factors, Touch, Vibrissae}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.4316-12.2013}, author = {Pammer, Lorenz and O{\textquoteright}Connor, Daniel H and Hires, S Andrew and Clack, Nathan G and Huber, Daniel and Myers, Eugene W and Svoboda, Karel} } @article {6146, title = {Neural coding during active somatosensation revealed using illusory touch.}, journal = {Nature Neuroscience}, volume = {16}, year = {2013}, month = {2013 Jun 2}, pages = {958-65}, abstract = {

Active sensation requires the convergence of external stimuli with representations of body movements. We used mouse behavior, electrophysiology and optogenetics to dissect the temporal interactions among whisker movement, neural activity and sensation of touch. We photostimulated layer 4 activity in single barrels in a closed loop with whisking. Mimicking touch-related neural activity caused illusory perception of an object at a particular location, but scrambling the timing of the spikes over one whisking cycle (tens of milliseconds) did not abolish the illusion, indicating that knowledge of instantaneous whisker position is unnecessary for discriminating object locations. The illusions were induced only during bouts of directed whisking, when mice expected touch, and in the relevant barrel. Reducing activity biased behavior, consistent with a spike count code for object detection at a particular location. Our results show that mice integrate coding of touch with movement over timescales of a whisking bout to produce perception of active touch.

}, issn = {1546-1726}, doi = {10.1038/nn.3419}, author = {O{\textquoteright}Connor, Daniel H and Hires, S Andrew and Guo, Zengcai V and Li, Nuo and Yu, Jianing and Sun, Qian-Quan and Huber, Daniel and Svoboda, Karel} } @article {6128, title = {An optimized fluorescent probe for visualizing glutamate neurotransmission.}, journal = {Nature Methods}, volume = {10}, year = {2013}, month = {2013 Feb}, pages = {162-70}, abstract = {

We describe an intensity-based glutamate-sensing fluorescent reporter (iGluSnFR) with signal-to-noise ratio and kinetics appropriate for in vivo imaging. We engineered iGluSnFR in vitro to maximize its fluorescence change, and we validated its utility for visualizing glutamate release by neurons and astrocytes in increasingly intact neurological systems. In hippocampal culture, iGluSnFR detected single field stimulus-evoked glutamate release events. In pyramidal neurons in acute brain slices, glutamate uncaging at single spines showed that iGluSnFR responds robustly and specifically to glutamate in situ, and responses correlate with voltage changes. In mouse retina, iGluSnFR-expressing neurons showed intact light-evoked excitatory currents, and the sensor revealed tonic glutamate signaling in response to light stimuli. In worms, glutamate signals preceded and predicted postsynaptic calcium transients. In zebrafish, iGluSnFR revealed spatial organization of direction-selective synaptic activity in the optic tectum. Finally, in mouse forelimb motor cortex, iGluSnFR expression in layer V pyramidal neurons revealed task-dependent single-spine activity during running.

}, keywords = {Animals, Astrocytes, Biosensing Techniques, Caenorhabditis elegans, Calcium Signaling, Escherichia coli Proteins, Excitatory Postsynaptic Potentials, Fluorescent Dyes, Glutamic Acid, Green Fluorescent Proteins, Hippocampus, Mice, Motor Cortex, Neurons, Photic Stimulation, Pyramidal Cells, Recombinant Fusion Proteins, Retina, Signal-To-Noise Ratio, Synaptic Transmission, Zebrafish}, issn = {1548-7105}, doi = {10.1038/nmeth.2333}, author = {Marvin, Jonathan S and Borghuis, Bart G and Tian, Lin and Cichon, Joseph and Harnett, Mark T and Akerboom, Jasper and Gordus, Andrew and Renninger, Sabine L. and Chen, Tsai-Wen and Bargmann, Cornelia I and Orger, Michael B. and Schreiter, Eric R and Demb, Jonathan B and Gan, Wen-Biao and Hires, S Andrew and Looger, Loren L} } @article {4303, title = {Laminar analysis of excitatory local circuits in vibrissal motor and sensory cortical areas.}, journal = {PLoS Biology}, volume = {9}, year = {2011}, month = {2011 Jan 4}, pages = {e1000572}, abstract = {

Rodents move their whiskers to locate and identify objects. Cortical areas involved in vibrissal somatosensation and sensorimotor integration include the vibrissal area of the primary motor cortex (vM1), primary somatosensory cortex (vS1; barrel cortex), and secondary somatosensory cortex (S2). We mapped local excitatory pathways in each area across all cortical layers using glutamate uncaging and laser scanning photostimulation. We analyzed these maps to derive laminar connectivity matrices describing the average strengths of pathways between individual neurons in different layers and between entire cortical layers. In vM1, the strongest projection was L2/3{\textrightarrow}L5. In vS1, strong projections were L2/3{\textrightarrow}L5 and L4{\textrightarrow}L3. L6 input and output were weak in both areas. In S2, L2/3{\textrightarrow}L5 exceeded the strength of the ascending L4{\textrightarrow}L3 projection, and local input to L6 was prominent. The most conserved pathways were L2/3{\textrightarrow}L5, and the most variable were L4{\textrightarrow}L2/3 and pathways involving L6. Local excitatory circuits in different cortical areas are organized around a prominent descending pathway from L2/3{\textrightarrow}L5, suggesting that sensory cortices are elaborations on a basic motor cortex-like plan.

}, keywords = {Animals, Brain Mapping, Mice, Motor Cortex, Nerve Net, Presynaptic Terminals, Somatosensory Cortex, Vibrissae}, issn = {1545-7885}, doi = {10.1371/journal.pbio.1000572}, author = {Hooks, B M and Hires, S Andrew and Zhang, Ying-Xin and Huber, Daniel and Petreanu, Leopoldo and Svoboda, Karel and Shepherd, Gordon M G} } @article {1555, title = {Crystal structures of the GCaMP calcium sensor reveal the mechanism of fluorescence signal change and aid rational design.}, journal = {The Journal of Biological Chemistry}, volume = {284}, year = {2009}, month = {2009 Mar 6}, pages = {6455-64}, abstract = {

The genetically encoded calcium indicator GCaMP2 shows promise for neural network activity imaging, but is currently limited by low signal-to-noise ratio. We describe x-ray crystal structures as well as solution biophysical and spectroscopic characterization of GCaMP2 in the calcium-free dark state, and in two calcium-bound bright states: a monomeric form that dominates at intracellular concentrations observed during imaging experiments and an unexpected domain-swapped dimer with decreased fluorescence. This series of structures provides insight into the mechanism of Ca2+-induced fluorescence change. Upon calcium binding, the calmodulin (CaM) domain wraps around the M13 peptide, creating a new domain interface between CaM and the circularly permuted enhanced green fluorescent protein domain. Residues from CaM alter the chemical environment of the circularly permuted enhanced green fluorescent protein chromophore and, together with flexible inter-domain linkers, block solvent access to the chromophore. Guided by the crystal structures, we engineered a series of GCaMP2 point mutants to probe the mechanism of GCaMP2 function and characterized one mutant with significantly improved signal-to-noise. The mutation is located at a domain interface and its effect on sensor function could not have been predicted in the absence of structural data.

}, keywords = {Animals, Calcium, Calcium-Binding Proteins, Crystallography, Fluorescent Dyes, Green Fluorescent Proteins, Models, Molecular, Peptides, Protein Binding, Protein Structure, Recombinant Fusion Proteins, Structure-Activity Relationship, Tertiary, X-Ray}, issn = {0021-9258}, doi = {10.1074/jbc.M807657200}, author = {Akerboom, Jasper and Rivera, Jonathan D V{\'e}lez and Guilbe, Mar{\'\i}a M Rodr{\'\i}guez and Malav{\'e}, Elisa C Alfaro and Hernandez, Hector H and Tian, Lin and Hires, S Andrew and Marvin, Jonathan S and Looger, Loren L and Schreiter, Eric R} } @article {1646, title = {Imaging neural activity in worms, flies and mice with improved GCaMP calcium indicators.}, journal = {Nature Methods}, volume = {6}, year = {2009}, month = {2009 Dec}, pages = {875-81}, abstract = {

Genetically encoded calcium indicators (GECIs) can be used to image activity in defined neuronal populations. However, current GECIs produce inferior signals compared to synthetic indicators and recording electrodes, precluding detection of low firing rates. We developed a single-wavelength GCaMP2-based GECI (GCaMP3), with increased baseline fluorescence (3-fold), increased dynamic range (3-fold) and higher affinity for calcium (1.3-fold). We detected GCaMP3 fluorescence changes triggered by single action potentials in pyramidal cell dendrites, with signal-to-noise ratio and photostability substantially better than those of GCaMP2, D3cpVenus and TN-XXL. In Caenorhabditis elegans chemosensory neurons and the Drosophila melanogaster antennal lobe, sensory stimulation-evoked fluorescence responses were significantly enhanced with GCaMP3 (4-6-fold). In somatosensory and motor cortical neurons in the intact mouse, GCaMP3 detected calcium transients with amplitudes linearly dependent on action potential number. Long-term imaging in the motor cortex of behaving mice revealed large fluorescence changes in imaged neurons over months.

}, keywords = {Animals, Brain, Caenorhabditis elegans, Calcium, Cell Line, Drosophila melanogaster, Fluorescence Resonance Energy Transfer, Humans, Mice, Neurons}, issn = {1548-7105}, doi = {10.1038/nmeth.1398}, author = {Tian, Lin and Hires, S Andrew and Mao, Tianyi and Huber, Daniel and Chiappe, M Eugenia and Chalasani, Sreekanth H and Petreanu, Leopoldo and Akerboom, Jasper and McKinney, Sean A and Schreiter, Eric R and Bargmann, Cornelia I and Jayaraman, Vivek and Svoboda, Karel and Looger, Loren L} } @article {4367, title = {Reporting neural activity with genetically encoded calcium indicators.}, journal = {Brain Cell Biology}, volume = {36}, year = {2008}, month = {2008 Aug 6}, pages = {69-86}, abstract = {

Genetically encoded calcium indicators (GECIs), based on recombinant fluorescent proteins, have been engineered to observe calcium transients in living cells and organisms. Through observation of calcium, these indicators also report neural activity. We review progress in GECI construction and application, particularly toward in vivo monitoring of sparse action potentials (APs). We summarize the extrinsic and intrinsic factors that influence GECI performance. A simple model of GECI response to AP firing demonstrates the relative significance of these factors. We recommend a standardized protocol for evaluating GECIs in a physiologically relevant context. A potential method of simultaneous optical control and recording of neuronal circuits is presented.

}, keywords = {Action Potentials, Animals, Calcium Signaling, Confocal, Electrophysiology, Luminescent Proteins, Microscopy, Neurons, Signal Transduction}, issn = {1559-7113}, doi = {10.1007/s11068-008-9029-4}, author = {Hires, S Andrew and Tian, Lin and Looger, Loren L} }