18 results on '"Julia Veit"'
Search Results
2. Complementary networks of cortical somatostatin interneurons enforce layer specific control
- Author
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Alexander Naka, Julia Veit, Ben Shababo, Rebecca K Chance, Davide Risso, David Stafford, Benjamin Snyder, Andrew Egladyous, Desiree Chu, Savitha Sridharan, Daniel P Mossing, Liam Paninski, John Ngai, and Hillel Adesnik
- Subjects
neocortex ,somatostatin ,inhibition ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
The neocortex is functionally organized into layers. Layer four receives the densest bottom up sensory inputs, while layers 2/3 and 5 receive top down inputs that may convey predictive information. A subset of cortical somatostatin (SST) neurons, the Martinotti cells, gate top down input by inhibiting the apical dendrites of pyramidal cells in layers 2/3 and 5, but it is unknown whether an analogous inhibitory mechanism controls activity in layer 4. Using high precision circuit mapping, in vivo optogenetic perturbations, and single cell transcriptional profiling, we reveal complementary circuits in the mouse barrel cortex involving genetically distinct SST subtypes that specifically and reciprocally interconnect with excitatory cells in different layers: Martinotti cells connect with layers 2/3 and 5, whereas non-Martinotti cells connect with layer 4. By enforcing layer-specific inhibition, these parallel SST subnetworks could independently regulate the balance between bottom up and top down input.
- Published
- 2019
- Full Text
- View/download PDF
3. Cortical VIP neurons locally control the gain but globally control the coherence of gamma band rhythms
- Author
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Julia Veit, Gregory Handy, Brent Doiron, Hillel Adesnik, and Daniel P. Mossing
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Physics ,Electrophysiology ,Visual perception ,Visual cortex ,medicine.anatomical_structure ,General Neuroscience ,medicine ,Biological neural network ,Stimulus (physiology) ,Optogenetics ,Neuroscience ,Synchronization ,Visual field - Abstract
Gamma band synchronization can facilitate local and long-range communication in neural circuits. In the primary visual cortex (V1) the strength of synchronization on the local level is strongly tuned to the contrast, size and center/surround orientation of grating stimuli. On the global level, the synchronization of gamma oscillations across the retinotopic map crucially depends on matched stimulus properties in the corresponding locations in the visual field. Although these features of V1 gamma rhythms are likely to be crucial for how they might support cortico-cortical communication and visual perception, their neural basis remains largely unknown. We hypothesized VIP disinhibitory interneurons, which shape other tuning properties in V1 by inhibiting SST neurons, may be responsible for tuning local gamma band power and global gamma synchronization. To test these ideas, we combined multi-electrode electrophysiology, cell-type specific optogenetic suppression of VIP neurons and computational modeling. Contrary to expectations, our data show that on the local level, VIP activity has no role in tuning gamma power to stimulus properties; rather, it scales the gain of gamma oscillations linearly across stimulus space and across behavioral state. Conversely, on the global level, VIP neurons specifically suppress gamma synchronization (as measured by spectral coherence) between spatially separated cortical ensembles when they are processing non-matched stimulus features. A straightforward computational model of V1 shows that like-to-like connectivity across retinotopic space, and specific, but powerful VIP➔SST inhibition are sufficient to capture these seemingly opposed effects. These data demonstrate how VIP neurons differentially impact local and global properties of gamma rhythms depending on the global statistics of the retinal image. VIP neurons may thus construct temporal filters in the gamma band for spatially continuous image features, such as contours, to facilitate the downstream generation of coherent visual percepts.
- Published
- 2023
- Full Text
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4. Antagonistic inhibitory subnetworks control cooperation and competition across cortical space
- Author
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Daniel P. Mossing, Hillel Adesnik, Agostina Palmigiano, Kenneth D. Miller, and Julia Veit
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biology ,Surround suppression ,Computer science ,Gating ,Optogenetics ,Feedback loop ,Calcium imaging ,Visual cortex ,medicine.anatomical_structure ,biology.protein ,medicine ,Neuroscience ,Parvalbumin ,Network model - Abstract
The cortical microcircuit can dynamically adjust to dramatic changes in the strength, scale, and complexity of its input. In the primary visual cortex (V1), pyramidal cells (PCs) integrate widely across space when signals are weak, but narrowly when signals are strong, a phenomenon known as contrast-dependent surround suppression. Theoretical work has proposed that local interneurons could mediate a shift from cooperation to competition of PCs across cortical space, underlying this computation. We combined calcium imaging and electrophysiology to constrain a stabilized supralinear network model that explains how the four principal cell types in layer 2/3 (L2/3) of mouse V1– somatostatin (SST), parvalbumin (PV), and vasoactive intestinal peptide (VIP) interneurons, and PCs– transform inputs from layer 4 (L4) PCs to encode drifting gratings of varying size and contrast. Using bidirectional optogenetic perturbations, we confirmed key predictions of the model. Our data and modeling showed that recurrent amplification drives a transition from a positive PC→VIP⊣SST⊣PC feedback loop at small size and low contrast to a negative PC→SST⊣PC feedback loop at large size and high contrast to contribute to this flexible computation. This may represent a widespread mechanism for gating competition across cortical space to optimally meet task demands.
- Published
- 2021
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5. Restoration of high-sensitivity and adapting vision with a cone opsin
- Author
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Amy Holt, Autoosa Salari, Benjamin Sivyer, Ehud Y. Isacoff, Meike Visel, Benjamin M. Gaub, Joshua Levitz, Julia Veit, Krisha Aghi, John G. Flannery, and Michael H. Berry
- Subjects
0301 basic medicine ,Keratinocytes ,Patch-Clamp Techniques ,genetic structures ,Computer science ,General Physics and Astronomy ,02 engineering and technology ,Inbred C57BL ,Blindness ,Eye ,chemistry.chemical_compound ,Mice ,Cone Opsin ,Contrast (vision) ,lcsh:Science ,media_common ,Multidisciplinary ,biology ,Retinal Degeneration ,Dependovirus ,610 Medical sciences ,Medicine ,021001 nanoscience & nanotechnology ,Cone Opsins ,Treatment Outcome ,ddc: 610 ,Rhodopsin ,Intravitreal Injections ,Retinal Cone Photoreceptor Cells ,0210 nano-technology ,media_common.quotation_subject ,Science ,Genetic Vectors ,Adaptation (eye) ,Optogenetics ,Article ,General Biochemistry, Genetics and Molecular Biology ,Retina ,Cell Line ,03 medical and health sciences ,MD Multidisciplinary ,Animals ,Humans ,Sensitivity (control systems) ,Eye Disease and Disorders of Vision ,Light sensitivity ,Animal ,Neurosciences ,Retinal ,General Chemistry ,Genetic Therapy ,eye diseases ,Mice, Inbred C57BL ,Disease Models, Animal ,030104 developmental biology ,chemistry ,Disease Models ,biology.protein ,lcsh:Q ,sense organs ,Neuroscience - Abstract
Inherited and age-related retinal degenerative diseases cause progressive loss of rod and cone photoreceptors, leading to blindness, but spare downstream retinal neurons, which can be targeted for optogenetic therapy. However, optogenetic approaches have been limited by either low light sensitivity or slow kinetics, and lack adaptation to changes in ambient light, and not been shown to restore object vision. We find that the vertebrate medium wavelength cone opsin (MW-opsin) overcomes these limitations and supports vision in dim light. MW-opsin enables an otherwise blind retinitis pigmenotosa mouse to discriminate temporal and spatial light patterns displayed on a standard LCD computer tablet, displays adaption to changes in ambient light, and restores open-field novel object exploration under incidental room light. By contrast, rhodopsin, which is similar in sensitivity but slower in light response and has greater rundown, fails these tests. Thus, MW-opsin provides the speed, sensitivity and adaptation needed to restore patterned vision., Nature Communications, 10 (1), ISSN:2041-1723
- Published
- 2020
- Full Text
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6. Basal forebrain activation enhances between-trial reliability of low-frequency local field potentials (LFP) and spiking activity in tree shrew primary visual cortex (V1)
- Author
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Paolo De Luna, Julia Veit, and Gregor Rainer
- Subjects
0301 basic medicine ,Histology ,Basal Forebrain ,Sensory Receptor Cells ,genetic structures ,Photic Stimulation ,Action Potentials ,Sensory system ,Local field potential ,Stimulus (physiology) ,Visual system ,Electroencephalography ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Animals ,Visual Pathways ,Visual Cortex ,Physics ,Basal forebrain ,medicine.diagnostic_test ,General Neuroscience ,Tupaiidae ,030104 developmental biology ,Visual cortex ,medicine.anatomical_structure ,nervous system ,Visual Perception ,Evoked Potentials, Visual ,Anatomy ,Neuroscience ,030217 neurology & neurosurgery - Abstract
Brain state has profound effects on neural processing and stimulus encoding in sensory cortices. While the synchronized state is dominated by low-frequency local field potential (LFP) activity, low-frequency LFP power is suppressed in the desynchronized state, where a concurrent enhancement in gamma power is observed. Recently, it has been shown that cortical desynchronization co-occurs with enhanced between-trial reliability of spiking activity in sensory neurons, but it is currently unclear whether this effect is also evident in LFP signals. Here, we address this question by recording both spike trains and LFP in primary visual cortex during natural movie stimulation, and using isoflurane anesthesia and basal forebrain (BF) electrical activation as proxies for synchronized and desynchronized brain states. We show that indeed, low-frequency LFP modulations ("LFP events") also occur more reliably following BF activation. Interestingly, while being more reliable, these LFP events are smaller in amplitude compared to those generated in the synchronized brain state. We further demonstrate that differences in reliability of spiking activity between cortical states can be linked to amplitude and probability of LFP events. The correlated temporal dynamics between low-frequency LFP and spiking response reliability in visual cortex suggests that these effects may both be the result of the same neural circuit activation triggered by BF stimulation, which facilitates switching between processing of incoming sensory information in the desynchronized and reverberation of internal signals in the synchronized state.
- Published
- 2017
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7. Complementary networks of cortical somatostatin interneurons enforce layer specific control
- Author
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Liam Paninski, David A. Stafford, Ben Shababo, Rebecca K. Chance, Alexander Naka, Benjamin Snyder, Andrew Egladyous, Davide Risso, Daniel P. Mossing, Julia Veit, Savitha Sridharan, John Ngai, Hillel Adesnik, and Desiree Chu
- Subjects
Genetics and Molecular Biology (all) ,inhibition ,mouse ,neocortex ,neuroscience ,somatostatin ,Neuroscience (all) ,Biochemistry, Genetics and Molecular Biology (all) ,Immunology and Microbiology (all) ,Neocortex ,Biochemistry ,Mice ,0302 clinical medicine ,Biology (General) ,0303 health sciences ,Chemistry ,General Neuroscience ,Pyramidal Cells ,General Medicine ,Somatostatin ,medicine.anatomical_structure ,Neurological ,Excitatory postsynaptic potential ,Medicine ,Research Article ,QH301-705.5 ,1.1 Normal biological development and functioning ,Science ,Sensory system ,Optogenetics ,Inhibitory postsynaptic potential ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,Underpinning research ,Interneurons ,medicine ,Animals ,030304 developmental biology ,General Immunology and Microbiology ,Gene Expression Profiling ,Neurosciences ,Barrel cortex ,Biochemistry and Cell Biology ,Nerve Net ,Neuroscience ,030217 neurology & neurosurgery - Abstract
The neocortex is functionally organized into layers. Layer four receives the densest bottom up sensory inputs, while layers 2/3 and 5 receive top down inputs that may convey predictive information. A subset of cortical somatostatin (SST) neurons, the Martinotti cells, gate top down input by inhibiting the apical dendrites of pyramidal cells in layers 2/3 and 5, but it is unknown whether an analogous inhibitory mechanism controls activity in layer 4. Using high precision circuit mapping, in vivo optogenetic perturbations, and single cell transcriptional profiling, we reveal complementary circuits in the mouse barrel cortex involving genetically distinct SST subtypes that specifically and reciprocally interconnect with excitatory cells in different layers: Martinotti cells connect with layers 2/3 and 5, whereas non-Martinotti cells connect with layer 4. By enforcing layer-specific inhibition, these parallel SST subnetworks could independently regulate the balance between bottom up and top down input.
- Published
- 2019
8. Author response: Complementary networks of cortical somatostatin interneurons enforce layer specific control
- Author
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Hillel Adesnik, David A. Stafford, Liam Paninski, Daniel P. Mossing, Benjamin Snyder, Rebecca K. Chance, Ben Shababo, Andrew Egladyous, Alexander Naka, Davide Risso, Savitha Sridharan, Julia Veit, Desiree Chu, and John Ngai
- Subjects
Somatostatin ,Layer (object-oriented design) ,Biology ,Control (linguistics) ,Neuroscience - Published
- 2019
- Full Text
- View/download PDF
9. Complementary networks of cortical somatostatin interneurons enforce layer specific control
- Author
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Alexander Naka, Julia Veit, Ben Shababo, Rebecca K. Chance, Davide Risso, David Stafford, Benjamin Snyder, Andrew Y. Egladyous, Desi Chu, Savitha Sridharan, Liam Paninski, John Ngai, and Hillel Adesnik
- Subjects
Cell type ,Neocortex ,medicine.anatomical_structure ,Somatostatin ,Chemistry ,Sensation ,medicine ,Excitatory postsynaptic potential ,Sensory system ,Optogenetics ,Inhibitory postsynaptic potential ,Neuroscience - Abstract
The neocortex is organized into discrete layers of excitatory neurons: layer 4 receives the densest ‘bottom up’ projection carrying external sensory data, while layers 2/3 and 5 receive ‘top down’ inputs from higher cortical areas that may convey sensory expectations and behavioral goals. A subset of cortical somatostatin (SST) neurons gate top down input and control sensory computation by inhibiting the apical dendrites of pyramidal cells in layers 2/3 and 5. However, it is unknown whether an analogous inhibitory mechanism separately and specifically controls activity in layer 4. We hypothesized that distinct SST circuits might exist to inhibit specific cortical layers. By enforcing layer-specific inhibition, distinct SST subnetworks could mediate pathway-specific gain control, such as regulating the balance between bottom up and top down input. Employing a combination of high precision circuit mapping, in vivo optogenetic perturbations, and single cell transcriptional profiling, we reveal distinct and complementary SST circuits that specifically and reciprocally interconnect with excitatory cells in either layer 4 or layers 2/3 and 5. Our data further define a transcriptionally distinct SST neuronal sub-class that powerfully gates bottom up sensory activity during active sensation by regulating layer 4 activity. This integrated paradigm further represents a potentially generalizable approach to identify and characterize neuronal cell types and reveal their in vivo function.
- Published
- 2018
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10. A direct translaminar inhibitory circuit tunes cortical output
- Author
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Richard Hakim, Scott R. Pluta, Hillel Adesnik, Gregory Telian, Lucille Yao, Alexander Naka, David Taylor, and Julia Veit
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Neurons ,Cortical circuits ,Sensory processing ,Extramural ,Nerve net ,General Neuroscience ,medicine.medical_treatment ,Brain ,Sensory system ,Mice, Transgenic ,Optogenetics ,Inhibitory postsynaptic potential ,Article ,Disease Models, Animal ,medicine.anatomical_structure ,Alzheimer Disease ,medicine ,Animals ,Calcium ,Sensory cortex ,Nerve Net ,Psychology ,Neuroscience - Abstract
Anatomical and physiological experiments have outlined a blueprint for the feedforward flow of activity in cortical circuits: signals are thought to propagate primarily from the middle cortical layer (layer 4, L4) up to L2/3 and down to the major cortical output layer (L5). Pharmacological manipulations, however, have contested this model and have suggested that L4 may not be critical for sensory responses of neurons in either superficial or deep layers. To address these conflicting models, we reversibly manipulated L4 activity in awake, behaving mice using cell type-specific optogenetics. In contrast with both prevailing models, we found that activity in L4 directly suppressed L5, in part by activating deep, fast-spiking inhibitory neurons. Our data suggest that the net effect of L4 activity is to sharpen the spatial representations of L5 neurons. Thus, we establish a previously unknown translaminar inhibitory circuit in the sensory cortex that acts to enhance the feature selectivity of cortical output.
- Published
- 2015
11. Cortical gamma band synchronization through somatostatin interneurons
- Author
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Terrence J. Sejnowski, Monika P. Jadi, Julia Veit, Hillel Adesnik, and Richard Hakim
- Subjects
0301 basic medicine ,Male ,Interneuron ,Sensory processing ,genetic structures ,medicine.medical_treatment ,Models, Neurological ,Mice, Transgenic ,Optogenetics ,Biology ,Article ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Interneurons ,Synchronization (computer science) ,medicine ,Animals ,Gamma Rhythm ,Computer Simulation ,Cortical Synchronization ,Visual Cortex ,musculoskeletal, neural, and ocular physiology ,General Neuroscience ,030104 developmental biology ,medicine.anatomical_structure ,Visual cortex ,Somatostatin ,nervous system ,Female ,Striate cortex ,Gamma band ,Neuroscience ,030217 neurology & neurosurgery ,Photic Stimulation - Abstract
Gamma band rhythms may synchronize distributed cell assemblies to facilitate information transfer within and across brain areas, yet their underlying mechanisms remain hotly debated. Most circuit models postulate that soma-targeting parvalbumin-positive GABAergic neurons are the essential inhibitory neuron subtype necessary for gamma rhythms. Using cell-type-specific optogenetic manipulations in behaving animals, we show that dendrite-targeting somatostatin (SOM) interneurons are critical for a visually induced, context-dependent gamma rhythm in visual cortex. A computational model independently predicts that context-dependent gamma rhythms depend critically on SOM interneurons. Further in vivo experiments show that SOM neurons are required for long-distance coherence across the visual cortex. Taken together, these data establish an alternative mechanism for synchronizing distributed networks in visual cortex. By operating through dendritic and not just somatic inhibition, SOM-mediated oscillations may expand the computational power of gamma rhythms for optimizing the synthesis and storage of visual perceptions.
- Published
- 2016
12. Functional and laminar dissociations between muscarinic and nicotinic cholinergic neuromodulation in the tree shrew primary visual cortex
- Author
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Robert Kretz, Gregor Rainer, Felix Bießmann, Julia Veit, and Anwesha Bhattacharyya
- Subjects
Chemistry ,General Neuroscience ,Sensory system ,Nicotinic agonist ,Visual cortex ,medicine.anatomical_structure ,Cortex (anatomy) ,Neuromodulation ,Muscarinic acetylcholine receptor ,medicine ,Cholinergic ,Neuroscience ,Acetylcholine ,medicine.drug - Abstract
Acetylcholine is an important neuromodulator involved in cognitive function. The impact of cholinergic neuromodulation on computations within the cortical microcircuit is not well understood. Here we investigate the effects of layer-specific cholinergic drug application in the tree shrew primary visual cortex during visual stimulation with drifting grating stimuli of varying contrast and orientation. We describe differences between muscarinic and nicotinic cholinergic effects in terms of both the layer of cortex and the attribute of visual representation. Nicotinic receptor activation enhanced the contrast response in the granular input layer of the cortex, while tending to reduce neural selectivity for orientation across all cortical layers. Muscarinic activation modestly enhanced the contrast response across cortical layers, and tended to improve orientation tuning. This resulted in highest orientation selectivity in the supra- and infragranular layers, where orientation selectivity was already greatest in the absence of pharmacological stimulation. Our results indicate that laminar position plays a crucial part in functional consequences of cholinergic stimulation, consistent with the differential distribution of cholinergic receptors. Nicotinic receptors function to enhance sensory representations arriving in the cortex, whereas muscarinic receptors act to boost the cortical computation of orientation tuning. Our findings suggest close homology between cholinergic mechanisms in tree shrew and primate visual cortices.
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- 2012
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13. A Comprehensive Optogenetic Pharmacology Toolkit for In Vivo Control of GABA(A) Receptors and Synaptic Inhibition
- Author
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Hillel Adesnik, Richard H. Kramer, Christopher M. Davenport, Wan-Chen Lin, Caleb M. Smith, Julia Veit, Neil M. Wilson, and Ming-Chi Tsai
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Patch-Clamp Techniques ,Phosphines ,Neuroscience(all) ,Receptor expression ,Green Fluorescent Proteins ,Pharmacology ,Neurotransmission ,Optogenetics ,Biology ,In Vitro Techniques ,Synaptic Transmission ,gamma-Aminobutyric acid ,Neurotransmitter receptor ,medicine ,Animals ,Humans ,Receptor ,Cells, Cultured ,gamma-Aminobutyric Acid ,Mice, Knockout ,Binding Sites ,GABAA receptor ,General Neuroscience ,Brain ,Neural Inhibition ,Synapsin ,Receptors, GABA-A ,Synapsins ,Mutation ,Neuroscience ,Photic Stimulation ,medicine.drug - Abstract
Exogenously expressed opsins are valuable tools for optogenetic control of neurons in circuits. A deeper understanding of neural function can be gained by bringing control to endogenous neurotransmitter receptors that mediate synaptic transmission. Here we introduce a comprehensive optogenetic toolkit for controlling GABA(A) receptor-mediated inhibition in the brain. We developed a series of photoswitch ligands and the complementary genetically modified GABA(A) receptor subunits. By conjugating the two components, we generated light-sensitive versions of the entire GABA(A) receptor family. We validated these light-sensitive receptors for applications across a broad range of spatial scales, from subcellular receptor mapping to in vivo photo-control of visual responses in the cerebral cortex. Finally, we generated a knockin mouse in which the "photoswitch-ready" version of a GABA(A) receptor subunit genomically replaces its wild-type counterpart, ensuring normal receptor expression. This optogenetic pharmacology toolkit allows scalable interrogation of endogenous GABA(A) receptor function with high spatial, temporal, and biochemical precision.
- Published
- 2015
14. On the relation between receptive field structure and stimulus selectivity in the tree shrew primary visual cortex
- Author
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Julia Veit, Robert Kretz, Anwesha Bhattacharyya, and Gregor Rainer
- Subjects
Male ,Cognitive Neuroscience ,Action Potentials ,Simple cell ,Stimulus (physiology) ,Tree shrew ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,0302 clinical medicine ,medicine ,Animals ,030304 developmental biology ,Visual Cortex ,Neurons ,Tupaia ,0303 health sciences ,biology ,biology.organism_classification ,Visual field ,Visual cortex ,medicine.anatomical_structure ,Receptive field ,Tupaiidae ,Female ,Functional organization ,Visual Fields ,Neuroscience ,030217 neurology & neurosurgery ,Photic Stimulation - Abstract
There are notable differences in functional properties of primary visual cortex (V1) neurons among mammalian species, particularly those concerning the occurrence of simple and complex cells and the generation of orientation selectivity. Here, we present quantitative data on receptive field (RF) structure, response modulation, and orientation tuning for single neurons in V1 of the tree shrew, a close relative of primates. We find that spatial RF subfield segregation, a criterion for identifying simple cells, was exceedingly small in the tree shrew V1. In contrast, many neurons exhibited elevated F1/F0 modulation that is often used as a simple cell marker. This apparent discrepancy can be explained by the robust stimulus polarity preference in tree shrew V1, which inflates F1/F0 ratio values. RF structure mapped with sparse-noise-which is spatially restricted and emphasizes thalamo-cortical feed-forward inputs-appeared unrelated to orientation selectivity. However, RF structure mapped using the Hartley subspace stimulus-which covers a large area of the visual field and recruits considerable intracortical processing-did predict orientation preference. Our findings reveal a number of striking similarities in V1 functional organization between tree shrews and primates, emphasizing the important role of intracortical recurrent processing in shaping V1 response properties in these species.
- Published
- 2013
15. Neuropeptide alterations in the tree shrew hypothalamus during volatile anesthesia
- Author
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Gregor Rainer, Filomena Petruzziello, Xiaozhe Zhang, Robert Kretz, Laetitia Fouillen, Julia Veit, and Anwesha Bhattacharyya
- Subjects
Cell signaling ,Biophysics ,Hypothalamus ,Nitrous Oxide ,Neuropeptide ,Biology ,Anesthesia, General ,Biochemistry ,Differential analysis ,Tree shrew ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Pain perception ,Animals ,Spectral analysis ,030304 developmental biology ,Tupaia ,0303 health sciences ,Isoflurane ,Neuropeptides ,Anesthesia ,030217 neurology & neurosurgery ,medicine.drug - Abstract
Neuropeptides are critical signaling molecules, involved in the regulation of diverse physiological processes including energy metabolism, pain perception and brain cognitive state. Prolonged general anesthesia has an impact on many of these processes, but the regulation of peptides by general anesthetics is poorly understood. In this study, we present an in-depth characterization of the hypothalamic neuropeptides of the tree shrew during volatile isoflurane/nitrous oxide anesthesia administered accompanying a neurosurgical procedure. Using a predicted-peptide database and hybrid spectral analysis, we first identified 85 peptides from the tree shrew hypothalamus. Differential analysis was then performed between control and experimental group animals. The levels of 12 hypothalamic peptides were up-regulated following prolonged general anesthesia. Our study revealed for the first time that several neuropeptides, including alpha-neoendorphin and somatostatin-14, were altered during general anesthesia. Our study broadens the scope for the involvement of neuropeptides in volatile anesthesia regulation, opening the possibility for investigating the associated regulatory mechanisms.
- Published
- 2012
16. Functional and laminar dissociations between muscarinic and nicotinic cholinergic neuromodulation in the tree shrew primary visual cortex
- Author
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Anwesha, Bhattacharyya, Felix, Bießmann, Julia, Veit, Robert, Kretz, and Gregor, Rainer
- Subjects
Contrast Sensitivity ,Neurotransmitter Agents ,Orientation ,Cholinergic Agents ,Tupaiidae ,Animals ,Nerve Net ,Receptors, Nicotinic ,Receptors, Muscarinic ,Photic Stimulation ,Membrane Potentials ,Visual Cortex - Abstract
Acetylcholine is an important neuromodulator involved in cognitive function. The impact of cholinergic neuromodulation on computations within the cortical microcircuit is not well understood. Here we investigate the effects of layer-specific cholinergic drug application in the tree shrew primary visual cortex during visual stimulation with drifting grating stimuli of varying contrast and orientation. We describe differences between muscarinic and nicotinic cholinergic effects in terms of both the layer of cortex and the attribute of visual representation. Nicotinic receptor activation enhanced the contrast response in the granular input layer of the cortex, while tending to reduce neural selectivity for orientation across all cortical layers. Muscarinic activation modestly enhanced the contrast response across cortical layers, and tended to improve orientation tuning. This resulted in highest orientation selectivity in the supra- and infragranular layers, where orientation selectivity was already greatest in the absence of pharmacological stimulation. Our results indicate that laminar position plays a crucial part in functional consequences of cholinergic stimulation, consistent with the differential distribution of cholinergic receptors. Nicotinic receptors function to enhance sensory representations arriving in the cortex, whereas muscarinic receptors act to boost the cortical computation of orientation tuning. Our findings suggest close homology between cholinergic mechanisms in tree shrew and primate visual cortices.
- Published
- 2012
17. Basal forebrain activation controls contrast sensitivity in primary visual cortex
- Author
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Anwesha Bhattacharyya, Robert Kretz, Gregor Rainer, Julia Veit, and Igor V. Bondar
- Subjects
Thalamus ,Stimulation ,Local field potential ,Contrast Sensitivity ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,0302 clinical medicine ,Prosencephalon ,Cortex (anatomy) ,Orientation ,medicine ,Animals ,Visual Pathways ,Cholinergic neuron ,Gamma oscillations ,Cholinergic ,030304 developmental biology ,Visual Cortex ,0303 health sciences ,Basal forebrain ,Brain Mapping ,Chemistry ,General Neuroscience ,Spectrum Analysis ,Tupaiidae ,Electric Stimulation ,Visual cortex ,medicine.anatomical_structure ,Evoked Potentials, Visual ,Neuroscience ,030217 neurology & neurosurgery ,Photic Stimulation ,Orientation tuning ,Research Article - Abstract
Background The basal forebrain (BF) regulates cortical activity by the action of cholinergic projections to the cortex. At the same time, it also sends substantial GABAergic projections to both cortex and thalamus, whose functional role has received far less attention. We used deep brain stimulation (DBS) in the BF, which is thought to activate both types of projections, to investigate the impact of BF activation on V1 neural activity. Results BF stimulation robustly increased V1 single and multi-unit activity, led to moderate decreases in orientation selectivity and a remarkable increase in contrast sensitivity as demonstrated by a reduced semi-saturation contrast. The spontaneous V1 local field potential often exhibited spectral peaks centered at 40 and 70 Hz as well as reliably showed a broad γ-band (30-90 Hz) increase following BF stimulation, whereas effects in a low frequency band (1-10 Hz) were less consistent. The broad γ-band, rather than low frequency activity or spectral peaks was the best predictor of both the firing rate increase and contrast sensitivity increase of V1 unit activity. Conclusions We conclude that BF activation has a strong influence on contrast sensitivity in V1. We suggest that, in addition to cholinergic modulation, the BF GABAergic projections play a crucial role in the impact of BF DBS on cortical activity.
- Published
- 2013
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18. Neural response dynamics of spiking and local field potential activity depend on CRT monitor refresh-rate in the tree shrew primary visual cortex
- Author
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Robert Kretz, Julia Veit, Anwesha Bhattacharyya, and Gregor Rainer
- Subjects
genetic structures ,Physiology ,Computer science ,Cathode ray tube ,Models, Neurological ,Action Potentials ,Local field potential ,Macaque ,Luminance ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,law ,biology.animal ,Reaction Time ,medicine ,Animals ,Physiology, Comparative ,Visual Cortex ,030304 developmental biology ,Neurons ,Brain Mapping ,0303 health sciences ,Communication ,Cathode Ray Tube ,biology ,business.industry ,General Neuroscience ,Tupaiidae ,Refresh rate ,Electrophysiology ,Visual cortex ,medicine.anatomical_structure ,Visual Fields ,business ,Neural coding ,Neuroscience ,Photic Stimulation ,030217 neurology & neurosurgery - Abstract
Neural response dynamics of spiking and local field potential activity depend on CRT monitor refresh rate in the tree shrew primary visual cortex. Entrainment of neural activity to luminance impulses during the refresh of cathode ray tube monitor displays has been observed in the primary visual cortex (V1) of humans and macaque monkeys. This entrainment is of interest because it tends to temporally align and thus synchronize neural responses at the millisecond timescale. Here we show that, in tree shrew V1, both spiking and local field potential activity are also entrained at cathode ray tube refresh rates of 120, 90, and 60 Hz, with weakest but still significant entrainment even at 120 Hz, and strongest entrainment occurring in cortical input layer IV. For both luminance increments (“white” stimuli) and decrements (“black” stimuli), refresh rate had a strong impact on the temporal dynamics of the neural response for subsequent luminance impulses. Whereas there was rapid, strong attenuation of spikes and local field potential to prolonged visual stimuli composed of luminance impulses presented at 120 Hz, attenuation was nearly absent at 60-Hz refresh rate. In addition, neural onset latencies were shortest at 120 Hz and substantially increased, by 15 ms, at 60 Hz. In terms of neural response amplitude, black responses dominated white responses at all three refresh rates. However, black/white differences were much larger at 60 Hz than at higher refresh rates, suggesting a mechanism that is sensitive to stimulus timing. Taken together, our findings reveal many similarities between V1 of macaque and tree shrew, while underscoring a greater temporal sensitivity of the tree shrew visual system.
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