scholarly journals Processing of motion boundary orientation in macaque V2

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Heng Ma ◽  
Pengcheng Li ◽  
Jiaming Hu ◽  
Xingya Cai ◽  
Qianling Song ◽  
...  
Keyword(s):  
Neural Circuit ◽  
Neuronal Response ◽  
Critical Role ◽  
Neural Mechanisms ◽  
Orientation Discrimination ◽  
Boundary Orientation ◽  
Area V2 ◽  
Correlated Activity ◽  
Object Based ◽  
Motion Boundaries

Human and nonhuman primates are good at identifying an object based on its motion, a task that is believed to be carried out by the ventral visual pathway. However, the neural mechanisms underlying such ability remains unclear. We trained macaque monkeys to do orientation discrimination for motion boundaries (MBs) and recorded neuronal response in area V2 with microelectrode arrays. We found 10.9% of V2 neurons exhibited robust orientation selectivity to MBs, and their responses correlated with monkeys’ orientation-discrimination performances. Furthermore, the responses of V2 direction-selective neurons recorded at the same time showed correlated activity with MB neurons for particular MB stimuli, suggesting that these motion-sensitive neurons made specific functional contributions to MB discrimination tasks. Our findings support the view that V2 plays a critical role in MB analysis and may achieve this through a neural circuit within area V2.

scholarly journals Multi-level neural mechanisms of object-based attention

2010 ◽  
Vol 10 (7) ◽  
pp. 176-176
Author(s):  
E. Cohen ◽  
F. Tong
Keyword(s):  
Neural Mechanisms ◽  
Object Based ◽  
Multi Level

scholarly journals Differences in chloride gradients allow for three distinct types of synaptic modulation by endocannabinoids

2016 ◽  
Vol 116 (2) ◽  
pp. 619-628 ◽  
Author(s):  
Yanqing Wang ◽  
Brian D. Burrell
Keyword(s):  
Neural Circuit ◽  
Critical Role ◽  
Low Frequency ◽  
Inhibitory Synapses ◽  
Primary Role ◽  
Synaptic Modulation ◽  
Hirudo Verbana ◽  
Frequency Stimulation ◽  
Circuit Output

Endocannabinoids can elicit persistent depression of excitatory and inhibitory synapses, reducing or enhancing (disinhibiting) neural circuit output, respectively. In this study, we examined whether differences in Cl−gradients can regulate which synapses undergo endocannabinoid-mediated synaptic depression vs. disinhibition using the well-characterized central nervous system (CNS) of the medicinal leech, Hirudo verbana. Exogenous application of endocannabinoids or capsaicin elicits potentiation of pressure (P) cell synapses and depression of both polymodal (Npoly) and mechanical (Nmech) nociceptive synapses. In P synapses, blocking Cl−export prevented endocannabinoid-mediated potentiation, consistent with a disinhibition process that has been indicated by previous experiments. In Nmechneurons, which are depolarized by GABA due to an elevated Cl−equilibrium potentials (ECl), endocannabinoid-mediated depression was prevented by blocking Cl−import, indicating that this decrease in synaptic signaling was due to depression of excitatory GABAergic input (disexcitation). Npolyneurons are also depolarized by GABA, but endocannabinoids elicit depression in these synapses directly and were only weakly affected by disruption of Cl−import. Consequently, the primary role of elevated EClmay be to protect Npolysynapses from disinhibition. All forms of endocannabinoid-mediated plasticity required activation of transient potential receptor vanilloid (TRPV) channels. Endocannabinoid/TRPV-dependent synaptic plasticity could also be elicited by distinct patterns of afferent stimulation with low-frequency stimulation (LFS) eliciting endocannabinoid-mediated depression of Npolysynapses and high-frequency stimulus (HFS) eliciting endocannabinoid-mediated potentiation of P synapses and depression of Nmechsynapses. These findings demonstrate a critical role of differences in Cl−gradients between neurons in determining the sign, potentiation vs. depression, of synaptic modulation under normal physiological conditions.

Consciousness, awareness of insight and neural mechanisms of schizophrenia

2015 ◽  
Vol 26 (3) ◽  
Author(s):  
Tereza Touskova ◽  
Petr Bob
Keyword(s):  
Information Integration ◽  
Conscious Experience ◽  
Critical Role ◽  
Neural Mechanisms ◽  
The Other ◽  
Self Awareness ◽  
Synchronous Activity ◽  
Self Monitoring ◽  
Mental Integration ◽  
The Brain

AbstractAccording to recent research, disturbances of self-awareness and conscious experience have a critical role in the pathophysiology of schizophrenia, and in this context, schizophrenia is currently understood as a disorder characterized by distortions of acts of awareness, self-consciousness, and self-monitoring. Together, these studies suggest that the processes of disrupted awareness and conscious disintegration in schizophrenia might be related and represented by similar disruptions on the brain level, which, in principle, could be explained by various levels of disturbed connectivity and information disintegration that may negatively affect usual patterns of synchronous activity constituting adaptive integrative functions of consciousness. On the other hand, mental integration based on self-awareness and insight may significantly increase information integration and directly influence neural mechanisms underlying basic pathophysiological processes in schizophrenia.

scholarly journals Hand placement near the visual stimulus improves orientation selectivity in V2 neurons

2015 ◽  
Vol 113 (7) ◽  
pp. 2859-2870 ◽  
Author(s):  
Carolyn J. Perry ◽  
Lauren E. Sergio ◽  
J. Douglas Crawford ◽  
Mazyar Fallah
Keyword(s):  
Visual Processing ◽  
Neuronal Response ◽  
Oculomotor System ◽  
Orientation Selectivity ◽  
Orientation Tuning ◽  
Area V2 ◽  
Visual Enhancement ◽  
Orthogonal Orientation ◽  
Psychophysical Studies ◽  
The Brain

Often, the brain receives more sensory input than it can process simultaneously. Spatial attention helps overcome this limitation by preferentially processing input from a behaviorally-relevant location. Recent neuropsychological and psychophysical studies suggest that attention is deployed to near-hand space much like how the oculomotor system can deploy attention to an upcoming gaze position. Here we provide the first neuronal evidence that the presence of a nearby hand enhances orientation selectivity in early visual processing area V2. When the hand was placed outside the receptive field, responses to the preferred orientation were significantly enhanced without a corresponding significant increase at the orthogonal orientation. Consequently, there was also a significant sharpening of orientation tuning. In addition, the presence of the hand reduced neuronal response variability. These results indicate that attention is automatically deployed to the space around a hand, improving orientation selectivity. Importantly, this appears to be optimal for motor control of the hand, as opposed to oculomotor mechanisms which enhance responses without sharpening orientation selectivity. Effector-based mechanisms for visual enhancement thus support not only the spatiotemporal dissociation of gaze and reach, but also the optimization of vision for their separate requirements for guiding movements.

scholarly journals Blind cavefish retain functional connectivity in the tectum despite loss of retinal input

2021 ◽  
Author(s):  
Evan Lloyd ◽  
Brittnee McDole ◽  
Martin Privat ◽  
James B. Jaggard ◽  
Erik Duboué ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Neural Circuit ◽  
Astyanax Mexicanus ◽  
Evolutionary Selection ◽  
Environmental Perturbation ◽  
Multiple Components ◽  
Correlated Activity ◽  
Retinal Input ◽  
Hybrid Fish ◽  
Blind Cavefish

AbstractSensory systems display remarkable plasticity and are under strong evolutionary selection. The Mexican cavefish, Astyanax mexicanus, consists of eyed river-dwelling surface populations, and multiple independent cave populations which have converged on eye loss, providing the opportunity to examine the evolution of sensory circuits in response to environmental perturbation. Functional analysis across multiple transgenic populations expressing GCaMP6s showed that functional connectivity of the optic tectum largely did not differ between populations, except for the selective loss of negatively correlated activity within the cavefish tectum, suggesting positively correlated neural activity is resistant to an evolved loss of input from the retina. Further, analysis of surface-cave hybrid fish reveals that changes in the tectum are genetically distinct from those encoding eye-loss. Together, these findings uncover the independent evolution of multiple components of the visual system and establish the use of functional imaging in A. mexicanus to study neural circuit evolution.

scholarly journals Dynamics of visual perceptual processing in freely behaving mice

2020 ◽  
Author(s):  
Wen-Kai You ◽  
Shreesh P. Mysore
Keyword(s):  
Visual Perception ◽  
Time Course ◽  
Neural Circuit ◽  
Short Term Memory ◽  
Human Perception ◽  
Orientation Discrimination ◽  
Sensory Encoding ◽  
Stimulus Features ◽  
Two Stages ◽  
Speed Accuracy

ABSTRACTMice are being used increasing commonly to study visual behaviors, but the time-course of their perceptual dynamics is unclear. Here, using conditional accuracy analysis, a powerful method used to analyze human perception, and drift diffusion modeling, we investigated the dynamics and limits of mouse visual perception with a 2AFC orientation discrimination task. We found that it includes two stages – a short, sensory encoding stage lasting ∼300 ms, which involves the speed-accuracy tradeoff, and a longer visual short-term memory-dependent (VSTM) stage lasting ∼1700 ms. Manipulating stimulus features or adding a foil affected the sensory encoding stage, and manipulating stimulus duration altered the VSTM stage, of mouse perception. Additionally, mice discriminated targets as brief as 100 ms, and exhibited classic psychometric curves in a visual search task. Our results reveal surprising parallels between mouse and human visual perceptual processes, and provide a quantitative scaffold for exploring neural circuit mechanisms of visual perception.

scholarly journals Spatial integration during active tactile sensation drives elementary shape perception

2020 ◽  
Author(s):  
Jennifer Brown ◽  
Ian Antón Oldenburg ◽  
Gregory I. Telian ◽  
Sandon Griffin ◽  
Mieke Voges ◽  
...  
Keyword(s):  
High Speed ◽  
Neural Circuit ◽  
Barrel Cortex ◽  
Object Identification ◽  
Surface Orientation ◽  
Orientation Discrimination ◽  
Spatial Integration ◽  
Two Photon ◽  
Photon Imaging ◽  
Two Photon Imaging

SummaryActive haptic sensation is critical for object identification and manipulation, such as for tool use in humans, or prey capture in rodents. The neural circuit basis for recognizing objects through active touch alone is poorly understood. To address this gap, we combined optogenetics, two photon imaging, and high-speed behavioral tracking in mice solving a novel surface orientation discrimination task with their whiskers. We found that orientation discrimination required animals to summate input from multiple whiskers specifically along the whisker arc. Many animals discriminated the orientation of the stimulus per se, as their performance was invariant to the specific location of the presented stimulus. Two photon imaging showed that populations of neurons in the barrel cortex encoded each of the discriminated orientations, and this coding depended on integration over the whisker array. Finally, acute optogenetic inactivation of the barrel cortex strongly impaired surface orientation discrimination, and even cell-type specific optogenetic suppression of layer 4 excitatory neurons degraded performance, implying a role for superficial layers in this computation. These data suggest a model in which spatial summation over an active haptic array generates representations of an object’s surface orientations. These computations may facilitate the encoding of complex three-dimensional objects during active exploration.

scholarly journals Role of matrix metalloproteinase-9 in neurodevelopmental disorders and plasticity in Xenopus tadpoles

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Sayali V Gore ◽  
Eric J James ◽  
Lin-chien Huang ◽  
Jenn J Park ◽  
Andrea Berghella ◽  
...  
Keyword(s):  
Matrix Metalloproteinase ◽  
Neurodevelopmental Disorders ◽  
Neuronal Development ◽  
Neural Circuit ◽  
Critical Role ◽  
Matrix Metalloproteinase 9 ◽  
Abnormal Development ◽  
Synaptic Connectivity ◽  
And Behavior ◽  
Metalloproteinase 9

Matrix metalloproteinase-9 (MMP-9) is a secreted endopeptidase targeting extracellular matrix proteins, creating permissive environments for neuronal development and plasticity. Developmental dysregulation of MMP-9 may also lead to neurodevelopmental disorders (ND). Here we test the hypothesis that chronically elevated MMP-9 activity during early neurodevelopment is responsible for neural circuit hyperconnectivity observed in Xenopus tadpoles after early exposure to valproic acid (VPA), a known teratogen associated with ND in humans. In Xenopus tadpoles, VPA exposure results in excess local synaptic connectivity, disrupted social behavior and increased seizure susceptibility. We found that overexpressing MMP-9 in the brain copies effects of VPA on synaptic connectivity, and blocking MMP-9 activity pharmacologically or genetically reverses effects of VPA on physiology and behavior. We further show that during normal neurodevelopment MMP-9 levels are tightly regulated by neuronal activity and required for structural plasticity. These studies show a critical role for MMP-9 in both normal and abnormal development.

scholarly journals Reflex sympathetic tachycardia during intravenous infusions in chronic spinal cats

1976 ◽  
Vol 230 (1) ◽  
pp. 25-29 ◽  
Author(s):  
VS Bishop ◽  
F Lombardi ◽  
A Malliani ◽  
M Pagani ◽  
G Recordati
Keyword(s):  
Spinal Cord ◽  
Heart Rate ◽  
Neural Circuit ◽  
Blood Substitute ◽  
Neural Mechanisms ◽  
Resting Heart Rate ◽  
Average Increase ◽  
Vagal Blockade ◽  
Intravenous Infusions ◽  
Reflex Tachycardia

The reflex tachycardia elicited by rapid intravenous infusions of a blood substitute was studied in 21 chronic cats with spinal sections at C8. All animals could breath spontaneously. The day after section the average resting heart rate (HR) and arterial pressure (AP) were 109 beats/min and 98/67 mmHg, respectively. Vagal blockade with atropine (0.5-0.7 mg/kg iv) was performed prior to each infusion, increasing the average HR To 127 beats/min. In 39 infusions in 21 cats the average increase in HR was 10 beats/min (range from -6 to +22 beats/min). A tachycardia was observed in all but five trials, four of which were obtained in two cats that subsequently responded with a tachycardia. In seven animals the neural circuit mediating the response was partially or totally interrupted by section of several thoracic dorsal roots (T1-T4 or T1-T6) and of the spinal cord at the inferior level of these sections (between T6 and T7). The tachycardia response was progressively reduced and finally abolished by these procedures. These experiments indicate that spinal neural mechanisms are likely to contribute to the phenomenon first described by Bainbridge.

From the periphery to the brain: Wiring the olfactory system

2011 ◽  
Vol 2 (4) ◽  
Author(s):  
Albert Blanchart ◽  
Laura López-Mascaraque
Keyword(s):  
Olfactory Bulb ◽  
Olfactory System ◽  
Neural Circuit ◽  
Critical Role ◽  
Precise Location ◽  
Reliable Transmission ◽  
Molecular Events ◽  
Perfect Model ◽  
Molecular Signals ◽  
The Brain

AbstractThe olfactory system represents a perfect model to study the interactions between the central and peripheral nervous systems in order to establish a neural circuit during early embryonic development. In addition, another important feature of this system is the capability to integrate new cells generated in two neurogenic zones: the olfactory epithelium in the periphery and the wall of the lateral ventricles in the CNS, both during development and adulthood. In all these processes the combination and sequence of specific molecular signals plays a critical role in the wiring of the olfactory axons, as well as the precise location of the incoming cell populations to the olfactory bulb. The purpose of this review is to summarize recent insights into the cellular and molecular events that dictate cell settling position and axonal trajectories from their origin in the olfactory placode to the formation of synapses in the olfactory bulb to ensure rapid and reliable transmission of olfactory information from the nose to the brain.

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