scholarly journals In vivo Imaging of Deep Cortical Layers using a Microprism

10.3791/1509 ◽  
2009 ◽  
Author(s):  
Thomas H. Chia ◽  
Michael J. Levene
Keyword(s):  
Cortical Layers

Physiology, Pharmacology, and Topography of Cholinergic Neocortical Oscillations In Vitro

1997 ◽  
Vol 77 (5) ◽  
pp. 2427-2445 ◽  
Author(s):  
Heath S. Lukatch ◽  
M. Bruce Maciver
Keyword(s):  
Current Source ◽  
Brain Slices ◽  
Receptor Activation ◽  
Brain Regions ◽  
Oscillatory Activity ◽  
Cortical Layers ◽  
Eeg Activity ◽  
Layer 2

Lukatch, Heath S. and M. Bruce MacIver. Physiology, pharmacology, and topography of cholinergic neocortical oscillations in vitro. J. Neurophysiol. 77: 2427–2445, 1997. Rat neocortical brain slices generated rhythmic extracellular field [microelectroencephalogram (micro-EEG)] oscillations at theta frequencies (3–12 Hz) when exposed to pharmacological conditions that mimicked endogenous ascending cholinergic and GABAergic inputs. Use of the specific receptor agonist and antagonist carbachol and bicuculline revealed that simultaneous muscarinic receptor activation and γ-aminobutyric acid-A (GABAA)-mediated disinhibition werenecessary to elicit neocortical oscillations. Rhythmic activity was independent of GABAB receptor activation, but required intact glutamatergic transmission, evidenced by blockade or disruption of oscillations by 6-cyano-7-nitroquinoxaline-2,3-dione and (±)-2-amino-5-phosphonovaleric acid, respectively. Multisite mapping studies showed that oscillations were localized to areas 29d and 18b (Oc2MM) and parts of areas 18a and 17. Peak oscillation amplitudes occurred in layer 2/3, and phase reversals were observed in layers 1 and 5. Current source density analysis revealed large-amplitude current sinks and sources in layers 2/3 and 5, respectively. An initial shift in peak inward current density from layer 1 to layer 2/3 indicated that two processes underlie an initial depolarization followed by oscillatory activity. Laminar transections localized oscillation-generating circuitry to superficial cortical layers and sharp-spike-generating circuitry to deep cortical layers. Whole cell recordings identified three distinct cell types based on response properties during rhythmic micro-EEG activity: oscillation-on (theta-on) and -off (theta-off) neurons, and transiently depolarizing glial cells. Theta-on neurons displayed membrane potential oscillations that increased in amplitude with hyperpolarization (from −30 to −90 mV). This, taken together with a glutamate antagonist-induced depression of rhythmic micro-EEG activity, indicated that cholinergically driven neocortical oscillations require excitatory synaptic transmission. We conclude that under the appropriate pharmacological conditions, neocortical brain slices were capable of producing localized theta frequency oscillations. Experiments examining oscillation physiology, pharmacology, and topography demonstrated that neocortical brain slice oscillations share many similarities with the in vivo and in vitro theta EEG activity recorded in other brain regions.

scholarly journals In Vivo Femtosecond Laser Subsurface Cortical Microtransections Attenuate Acute Rat Focal Seizures

2018 ◽  
Vol 29 (8) ◽  
pp. 3415-3426
Author(s):  
Shivathmihai Nagappan ◽  
Lena Liu ◽  
Robert Fetcho ◽  
John Nguyen ◽  
Nozomi Nishimura ◽  
...  
Keyword(s):  
Laser Pulses ◽  
Epileptic Focus ◽  
Recording Electrode ◽  
Cortical Layers ◽  
Cortical Function ◽  
Human Epilepsy ◽  
Initiation And Propagation ◽  
Somatosensory Responses ◽  
A New Technique

Abstract Recent evidence shows that seizures propagate primarily through supragranular cortical layers. To selectively modify these circuits, we developed a new technique using tightly focused, femtosecond infrared laser pulses to make as small as ~100 µm-wide subsurface cortical incisions surrounding an epileptic focus. We use this “laser scalpel” to produce subsurface cortical incisions selectively to supragranular layers surrounding an epileptic focus in an acute rodent seizure model. Compared with sham animals, these microtransections completely blocked seizure initiation and propagation in 1/3 of all animals. In the remaining animals, seizure frequency was reduced by 2/3 and seizure propagation reduced by 1/3. In those seizures that still propagated, it was delayed and reduced in amplitude. When the recording electrode was inside the partially isolated cube and the seizure focus was on the outside, the results were even more striking. In spite of these microtransections, somatosensory responses to tail stimulation were maintained but with reduced amplitude. Our data show that just a single enclosing wall of laser cuts limited to supragranular layers led to a significant reduction in seizure initiation and propagation with preserved cortical function. Modification of this concept may be a useful treatment for human epilepsy.

scholarly journals Motor Learning Drives Dynamic Patterns of Intermittent Myelination on Behaviorally-Activated Axons

2021 ◽  
Author(s):  
Clara M. Bacmeister ◽  
Rongchen Huang ◽  
Michael A. Thornton ◽  
Lauren Conant ◽  
Anthony R. Chavez ◽  
...  
Keyword(s):  
Motor Learning ◽  
Computational Modeling ◽  
Learning And Memory ◽  
Neuronal Activity ◽  
Neural Circuits ◽  
Cortical Layers ◽  
Nodes Of Ranvier ◽  
Two Photon ◽  
Myelin Sheaths

Myelin plasticity occurs when newly-formed and pre-existing oligodendrocytes remodel existing myelination. Recent studies show these processes occur in response to changes in neuronal activity and are required for learning and memory. However, the link between behaviorally-relevant neuronal activity and circuit-specific changes in myelination remains unknown. Using longitudinal, in vivo two-photon imaging and targeted labeling of behaviorally-activated neurons, we explore how the pattern of intermittent myelination is altered on individual cortical axons during learning of a dexterous reach task. We show that learning-induced plasticity is targeted to behaviorally-activated axons and occurs in a staged response across cortical layers. During learning, myelin sheaths retract, lengthening nodes of Ranvier. Following learning, addition of new sheaths increases the number of continuous stretches of myelination. Computational modeling suggests these changes initially slow and subsequently increase conduction speed. Thus, behaviorally-activated, circuit-specific changes to myelination may fundamentally alter how information is transferred in neural circuits during learning.

scholarly journals Three-photon imaging of synthetic dyes in deep layers of the neocortex

2020 ◽  
Author(s):  
Chao J. Liu ◽  
Arani Roy ◽  
Anthony A. Simons ◽  
Deano M. Farinella ◽  
Prakash Kara
Keyword(s):  
Multiphoton Microscopy ◽  
Synthetic Dyes ◽  
Visual Responses ◽  
Cortical Layers ◽  
Imaging Tool ◽  
Functional Dynamics ◽  
Calcium Indicator ◽  
Deep Layers ◽  
Photon Imaging

AbstractMultiphoton microscopy has emerged as the primary imaging tool for studying the structural and functional dynamics of neural circuits in brain tissue, which is highly scattering to light. Recently, three-photon microscopy has enabled high-resolution fluorescence imaging of neurons in deeper brain areas that lie beyond the reach of conventional two-photon microscopy, which is typically limited to ~450 μm. Three-photon imaging of neuronal calcium signals, through the genetically-encoded calcium indicator GCaMP6, has been used to successfully record neuronal activity in deeper neocortical layers and parts of the hippocampus. Bulk-loading cells in deeper cortical layers with synthetic calcium indicators could provide an alternative strategy for labelling that obviates dependence on viral tropism and promoter penetration. Here we report a strategy for visualized injection of a calcium dye, Oregon Green BAPTA-1 AM (OGB-1 AM), at 500–600 μm below the surface of the mouse visual cortex in vivo. We demonstrate successful OGB-1 AM loading of cells in cortical layers 5–6 and subsequent three-photon imaging of orientation- and direction-selective visual responses from these cells.

Physiological Properties of Macaque V1 Neurons are Correlated With Extracellular Spike Amplitude, Duration, and Polarity

1999 ◽  
Vol 82 (3) ◽  
pp. 1451-1464 ◽  
Author(s):  
Moshe Gur ◽  
Alexander Beylin ◽  
D. Max Snodderly
Keyword(s):  
Cell Size ◽  
Action Potentials ◽  
Functional Organization ◽  
Brain Regions ◽  
Small Cells ◽  
Cortical Layers ◽  
Stimulus Motion ◽  
V1 Neurons ◽  
Physiological Properties

In the lateral geniculate nucleus (LGN) the large neurons of the magnocellular layers are functionally distinct and anatomically segregated from the small neurons of the parvocellular layers. This segregation of large and small cells is not maintained in the primary visual cortex (V1); instead a heterogeneous mixture of cells occurs, particularly in the output layers. Nevertheless, our results indicate that for the middle and upper layers of V1, cell size remains a predictor of physiological properties. We recorded extracellularly from neurons in V1 of alert monkeys and analyzed the amplitude, duration, and polarity of the action potentials of 199 cells. Of 156 cells that could be assigned to specific cortical layers, 137 (88%) were localized to the middle and upper cortical layers, layer 4 and above. We summarize evidence that the large-amplitude spikes are discharged by large cells, whereas small-amplitude spikes are the action potentials of smaller cells. Large spikes were predominantly negative and of longer duration, whereas small spikes were predominantly positive and briefer. The putative large cells had lower ongoing activity, smaller receptive field activating regions and higher selectivity for stimulus geometry and stimulus motion than the small cells. The contrasting properties of the large and the small cells were illustrated dramatically in simultaneous recordings made from adjacent cells. Our results imply that there may be an anatomic pairing or clustering of small and large cells that could be integral to the functional organization of the cortex. We suggest that the small and the large cells of area V1 have different roles, such that the small cells may shape the properties of the large output cells. If some of the small cells are also output cells, then cell size should be a predictor of the type of information being sent to other brain regions. Because of their high activity and relative ease of stimulation, the small cells also may contribute disproportionately to in vivo images based on metabolic responses such as changes in blood flow.

Dynamic Properties of Corticothalamic Neurons and Local Cortical Interneurons Generating Fast Rhythmic (30–40 Hz) Spike Bursts

1998 ◽  
Vol 79 (1) ◽  
pp. 483-490 ◽  
Author(s):  
Mircea Steriade ◽  
Igor Timofeev ◽  
Niklaus Dürmüller ◽  
François Grenier
Keyword(s):  
Cortical Neurons ◽  
Dynamic Properties ◽  
Synaptic Activity ◽  
Cortical Layers ◽  
Electrophysiological Properties ◽  
Cortical Interneurons ◽  
Cell Depolarization ◽  
Spike Bursts ◽  
40 Hz

Steriade, Mircea, Igor Timofeev, Niklaus Dürmüller, and François Grenier. Dynamic properties of corticothalamic neurons and local cortical interneurons generating fast rhythmic (30–40 Hz) spike-bursts. J. Neurophysiol. 79: 483–490, 1998. Fast spontaneous oscillations (mainly 30–40 Hz) characterize cortical and thalamic neuronal networks during behavioral states of increased vigilance and depend on cell depolarization under the influence of ascending activating systems. We investigated, by means of intracellular recording and staining in vivo, the properties of fast-oscillating cortical neurons from cat's motor and association areas, some projecting to the thalamus, others with locally arborizing axons. At a given level of depolarization, 28% of our neuronal sample discharged high-frequency spike bursts (300–600 Hz) that recurred rhythmically between 20 and 50 Hz. Such fast rhythmic bursting neurons have been found in both superficial and deep cortical layers. Slight changes in membrane potential as well as synaptic activity in thalamocortical networks dramatically altered the discharge patterns, from single spikes to rhythmic spike-bursts, and eventually to fast tonic firing without frequency adaptation. Thus our data challenge the conventional idea that sharply defined, invariant features and distinct locations in certain cortical layers characterize some neocortical cell-classes. We demonstrate that the distinctions between intrinsic electrophysiological properties of neocortical neurons are much more labile than conventionally thought. The present results, which indicate that corticothalamic neurons discharge fast rhythmic spike bursts mainly at 30–40 Hz, suggest that this activity results in integrated fast oscillations within corticothalamic networks.

Microprisms for In Vivo Multilayer Cortical Imaging

2009 ◽  
Vol 102 (2) ◽  
pp. 1310-1314 ◽  
Author(s):  
Thomas H. Chia ◽  
Michael J. Levene
Keyword(s):  
Neuronal Damage ◽  
Cell Damage ◽  
Surrounding Tissue ◽  
Wide Field ◽  
Cortical Layers ◽  
Two Photon ◽  
Simultaneous Imaging ◽  
Cortical Imaging ◽  
Layer V

Cortical slices allow for simultaneous imaging of multiple cortical layers. However, slices lack native physiological inputs and outputs. Although in vivo, two-photon imaging preserves the native context, it is typically limited to a depth of <500 μm. In addition, simultaneous imaging of multiple cortical layers is difficult due to the stratified organization of the cortex. We demonstrate the use of 1-mm microprisms for in vivo, two-photon neocortical imaging. These prisms enable simultaneous imaging of multiple cortical layers, including layer V, at an angle typical of slice preparations. Images were collected from the mouse motor and somatosensory cortex and show a nearly 900-μm-wide field of view. At high-magnification imaging using an objective with 1-mm of coverglass correction, resolution is sufficient to resolve dendritic spines on layer V neurons. Images collected using the microprism are comparable to images collected from a traditional slice preparation. Functional imaging of blood flow at various neocortical depths is also presented, allowing for quantification of red blood cell flux and velocity. H&E staining shows the surrounding tissue remains in its native, stratified organization. Estimation of neuronal damage using propidium iodide and a fluorescent Nissl stain reveals cell damage is limited to <100 μm from the tissue–glass interface. Microprisms are a straightforward tool offering numerous advantages for INTO NEOCORTICAL STISSUE.

scholarly journals Altered In Vitro and In Vivo Flumazenil Binding in Human Epileptogenic Neocortex

1999 ◽  
Vol 19 (9) ◽  
pp. 939-947 ◽  
Author(s):  
Ferenc Nagy ◽  
Diane C. Chugani ◽  
Csaba Juhász ◽  
Ednéa A. da Silva ◽  
Otto Muzik ◽  
...  
Keyword(s):  
Paired Comparison ◽  
Epileptic Focus ◽  
Compensatory Mechanism ◽  
Trauma Patients ◽  
Cortical Layers ◽  
Positron Emission ◽  
Laminar Distribution ◽  
And Control

In vitro and in vivo parameters of flumazenil (FMZ) binding were measured in spiking and nonspiking neocortex identified by intraoperative elcctrocorticography in epileptic patients who underwent cortical resection for seizure control. In vitro measures of receptor affinity (KD), number (Bmax) and laminar distribution for [3H]-FMZ binding in the epileptic focus (n = 38) were compared to nonspiking cortex from a subgroup of the patients (n = 12) and to tissue obtained from trauma patients (n = 5). The in vitro binding parameters were compared to in vivo [11C]-FMZ binding measured with positron emission tomography (PET) (n = 19). The Bmax was higher in the 38 spiking tissues as compared to the 12 nonspiking tissues ( P = .012). Paired comparison of spiking versus nonspiking binding in the 12 patients from whom nonspiking tissue was available showed increases in both KD ( P = .037) and Bmax ( P = .0047) in spiking cortex. A positive correlation was found between KD and Bmax values for 38 patients (r = 0.55, P < .0001), the magnitude of the KD increase being twice that of the Bmax increase. In addition, there was a significant correlation between the asymmetry indices of the in vivo FMZ binding on PET and in vitro KD of spiking cortex (n = 19, r = 0.52, P = .02). The laminar distribution of [3H]-FMZ showed increased FMZ binding in cortical layers V-VI in spiking cortex compared to nonspiking and control cortex. The increased receptor number in spiking cortical layers V-VI may be a compensatory mechanism to decreased GABAergic input. The increased Bmax in spiking cortex was accompanied by a larger decrease in the affinity of FMZ for the receptor suggesting that decreased FMZ binding in the epileptic focus measured with PET is due to a decrease in the affinity of the tracer for the receptor.

scholarly journals Improved cortical boundary registration for locally distorted fMRI scans

2018 ◽  
Author(s):  
Tim van Mourik ◽  
Peter J Koopmans ◽  
David G Norris
Keyword(s):  
Gold Standard ◽  
Static Field ◽  
Distortion Correction ◽  
Cortical Surface ◽  
Planar Imaging ◽  
Cortical Layers ◽  
Echo Planar ◽  
Clear Increase ◽  
The Brain

AbstractWith continuing advances in MRI techniques and the emergence of higher static field strengths, submillimetre spatial resolution is now possible in human functional imaging experiments. This has opened up the way for more specific types of analysis, for example investigation of the cortical layers of the brain. With this increased specificity, it is important to correct for the geometrical distortions that are inherent to echo planar imaging (EPI). Inconveniently, higher field strength also increases these distortions. The resulting displacements can easily amount to several millimetres and as such pose a serious problem for laminar analysis. We here present a method, Recursive Boundary Registration (RBR), that corrects distortions between an anatomical and an EPI volume. By recursively applying Boundary Based Registration (BBR) on progressively smaller subregions of the brain we generate an accurate whole-brain registration, based on the grey-white matter contrast. Explicit care is taken that the deformation does not break the topology of the cortical surface, which is an important requirement for several of the most common subsequent steps in laminar analysis. We show that RBR obtains submillimetre accuracy with respect to a manually distorted gold standard, and apply it to a set of human in vivo scans to show a clear increase in spacial specificity. RBR further automates the process of non-linear distortion correction. This is an important step towards routine human laminar fMRI. We provide the code for the RBR algorithm, as well as a variety of functions to better investigate registration performance in a public GitHub repository, https://github.com/TimVanMourik/OpenFmriAnalysis, under the GPL 3.0 license.

scholarly journals Lamina-specific AMPA receptor dynamics following visual deprivation in vivo

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Han L Tan ◽  
Richard H Roth ◽  
Austin R Graves ◽  
Robert H Cudmore ◽  
Richard L Huganir
Keyword(s):  
Ampa Receptor ◽  
Brain Function ◽  
Visual Deprivation ◽  
Cortical Layers ◽  
Two Photon ◽  
Dependent Change ◽  
Receptor Dynamics ◽  
Neuronal Connections ◽  
Apical Dendrites

Regulation of AMPA receptor (AMPAR) expression is central to synaptic plasticity and brain function, but how these changes occur in vivo remains elusive. Here, we developed a method to longitudinally monitor the expression of synaptic AMPARs across multiple cortical layers in awake mice using two-photon imaging. We observed that baseline AMPAR expression in individual spines is highly dynamic with more dynamics in primary visual cortex (V1) layer 2/3 (L2/3) neurons than V1 L5 neurons. Visual deprivation through binocular enucleation induces a synapse-specific and depth-dependent change of synaptic AMPARs in V1 L2/3 neurons, wherein deep synapses are potentiated more than superficial synapses. The increase is specific to L2/3 neurons and absent on apical dendrites of L5 neurons, and is dependent on expression of the AMPAR-binding protein GRIP1. Our study demonstrates that specific neuronal connections, across cortical layers and even within individual neurons, respond uniquely to changes in sensory experience.

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