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Superior colliculus

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https://www.readbyqxmd.com/read/28424576/defensive-vocalizations-and-motor-asymmetry-triggered-by-disinhibition-of-the-periaqueductal-gray-in-non-human-primates
#1
Patrick A Forcelli, Hannah F Waguespack, Ludise Malkova
Rapid and reflexive responses to threats are present across phylogeny. The neural circuitry mediating reflexive defense reactions has been well-characterized in a variety of species, for example, in rodents and cats, the detection of and species-typical response to threats is mediated by a network of structures including the midbrain tectum (deep and intermediate layers of the superior colliculus [DLSC]), periaqueductal gray (PAG), and forebrain structures such as the amygdala and hypothalamus. However, relatively little is known about the functional architecture of defense circuitry in primates...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28413825/color-change-detection-activity-in-the-primate-superior-colliculus
#2
James P Herman, Richard J Krauzlis
The primate superior colliculus (SC) is a midbrain structure that participates in the control of spatial attention. Previous studies examining the role of the SC in attention have mostly used luminance-based visual features (e.g., motion, contrast) as the stimuli and saccadic eye movements as the behavioral response, both of which are known to modulate the activity of SC neurons. To explore the limits of the SC's involvement in the control of spatial attention, we recorded SC neuronal activity during a task using color, a visual feature dimension not traditionally associated with the SC, and required monkeys to detect threshold-level changes in the saturation of a cued stimulus by releasing a joystick during maintained fixation...
March 2017: ENeuro
https://www.readbyqxmd.com/read/28407001/effect-of-hypoxia-on-the-retina-and-superior-colliculus-of-neonatal-pigs
#3
Noelia Ruzafa, Carmen Rey-Santano, Victoria Mielgo, Xandra Pereiro, Elena Vecino
PURPOSE: To evaluate the effect of hypoxia on the neonatal pig retina and brain, we analysed the retinal ganglion cells (RGCs) and neurons in the superior colliculus, as well as the response of astrocytes in both these central nervous system (CNS) structures. METHODS: Newborn pigs were exposed to 120 minutes of hypoxia, induced by decreasing the inspiratory oxygen fraction (FiO2: 10-15%), followed by a reoxygenation period of 240 minutes (FiO2: 21-35%). RGCs were quantified using Brn3a, a specific nuclear marker for these cells, and apoptosis was assessed through the appearance of active caspase-3...
2017: PloS One
https://www.readbyqxmd.com/read/28392756/brain-metabolic-changes-in-rats-following-acoustic-trauma
#4
Jun He, Yejin Zhu, Jiye Aa, Paul F Smith, Dirk De Ridder, Guangji Wang, Yiwen Zheng
Acoustic trauma is the most common cause of hearing loss and tinnitus in humans. However, the impact of acoustic trauma on system biology is not fully understood. It has been increasingly recognized that tinnitus caused by acoustic trauma is unlikely to be generated by a single pathological source, but rather a complex network of changes involving not only the auditory system but also systems related to memory, emotion and stress. One obvious and significant gap in tinnitus research is a lack of biomarkers that reflect the consequences of this interactive "tinnitus-causing" network...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28388698/the-magnification-factor-accounts-for-the-greater-hypometria-and-imprecision-of-larger-saccades-evidence-from-a-parametric-human-behavioral-study
#5
Françoise Vitu, Soazig Casteau, Hossein Adeli, Gregory J Zelinsky, Eric Castet
Saccades quite systematically undershoot a peripheral visual target by about 10% of its eccentricity while becoming more variable, mainly in amplitude, as the target becomes more peripheral. This undershoot phenomenon has been interpreted as the strategic adjustment of saccadic gain downstream of the superior colliculus (SC), where saccades are programmed. Here, we investigated whether the eccentricity-related increase in saccades' hypometria and imprecision might not instead result from overrepresentation of space closer to the fovea in the SC and visual-cortical areas...
April 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/28379979/rat-superior-colliculus-neurons-respond-to-large-visual-stimuli-flashed-outside-the-classical-receptive-field
#6
Juntaute Bytautiene, Gytis Baranauskas
Spatial integration of visual stimuli is a crucial step in visual information processing yet it is often unclear where this integration takes place in the visual system. In the superficial layers of the superior colliculus that form an early stage in visual information processing, neurons are known to have relatively small visual receptive fields, suggesting limited spatial integration. Here it is shown that at least for rats this conclusion may be wrong. Extracellular recordings in urethane-anaesthetized young adult rats (1...
2017: PloS One
https://www.readbyqxmd.com/read/28361990/a-retinoraphe-projection-regulates-serotonergic-activity-and-looming-evoked-defensive-behaviour
#7
Lu Huang, Tifei Yuan, Minjie Tan, Yue Xi, Yu Hu, Qian Tao, Zhikai Zhao, Jiajun Zheng, Yushui Han, Fuqiang Xu, Minmin Luo, Patricia J Sollars, Mingliang Pu, Gary E Pickard, Kwok-Fai So, Chaoran Ren
Animals promote their survival by avoiding rapidly approaching objects that indicate threats. In mice, looming-evoked defensive responses are triggered by the superior colliculus (SC) which receives direct retinal inputs. However, the specific neural circuits that begin in the retina and mediate this important behaviour remain unclear. Here we identify a subset of retinal ganglion cells (RGCs) that controls mouse looming-evoked defensive responses through axonal collaterals to the dorsal raphe nucleus (DRN) and SC...
March 31, 2017: Nature Communications
https://www.readbyqxmd.com/read/28334242/reciprocal-connections-between-cortex-and-thalamus-contribute-to-retinal-axon-targeting-to-dorsal-lateral-geniculate-nucleus
#8
Yupu Diao, Liyuan Cui, Yuqing Chen, Timothy J Burbridge, Wenqi Han, Brunhilde Wirth, Nenad Sestan, Michael C Crair, Jiayi Zhang
The dorsal Lateral Geniculate Nucleus (dLGN) is the primary image-forming target of the retina and shares a reciprocal connection with primary visual cortex (V1). Previous studies showed that corticothalamic input is essential for the development of thalamocortical projections, but less is known about the potential role of this reciprocal connection in the development of retinal projections. Here, we show a deficit of retinal innervation in the dLGN around E18.5 in Tra2β conditional knockout (cKO) "cortexless" mice, an age when apoptosis occurs along the thalamocortical tract and in some dLGN neurons...
March 10, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28324979/strategies-to-improve-stimulation-efficiency-for-retinal-prostheses
#9
Navya S Davuluri, Kiran Nimmagadda, Artin Petrossians, Mark S Humayun, James D Weiland
Retinitis Pigmentosa (RP) is a degenerative disease of the retina that leads to vision loss. Retinal prostheses are being developed in order to restore functional vision in patients suffering from RP. We conducted in-vivo experiments in order to identify strategies to efficiently stimulate the retina. We electrically stimulated the retina and measured electrically evoked potentials (EERs) from the superior colliculus of rats. We compared the strength of EERs when voltage-controlled and current-controlled pulses of varying pulse width and charge levels were applied to the retina...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28322188/a-molecular-mechanism-for-the-topographic-alignment-of-convergent-neural-maps
#10
Elise Savier, Stephen J Eglen, Amélie Bathélémy, Martine Perraut, Frank W Pfrieger, Greg Lemke, Michael Reber
Sensory processing requires proper alignment of neural maps throughout the brain. In the superficial layers of the superior colliculus of the midbrain, converging projections from retinal ganglion cells and neurons in visual cortex must be aligned to form a visuotopic map, but the basic mechanisms mediating this alignment remain elusive. In a new mouse model, ectopic expression of ephrin-A3 (Efna3) in a subset of retinal ganglion cells, quantitatively altering the retinal EFNAs gradient, disrupts cortico-collicular map alignment onto the retino-collicular map, creating a visuotopic mismatch...
March 14, 2017: ELife
https://www.readbyqxmd.com/read/28298886/mapping-and-analysis-of-the-connectome-of-sympathetic-premotor-neurons-in-the-rostral-ventrolateral-medulla-of-the-rat-using-a-volumetric-brain-atlas
#11
Bowen Dempsey, Sheng Le, Anita Turner, Phil Bokiniec, Radhika Ramadas, Jan G Bjaalie, Clement Menuet, Rachael Neve, Andrew M Allen, Ann K Goodchild, Simon McMullan
Spinally projecting neurons in the rostral ventrolateral medulla (RVLM) play a critical role in the generation of vasomotor sympathetic tone and are thought to receive convergent input from neurons at every level of the neuraxis; the factors that determine their ongoing activity remain unresolved. In this study we use a genetically restricted viral tracing strategy to definitively map their spatially diffuse connectome. We infected bulbospinal RVLM neurons with a recombinant rabies variant that drives reporter expression in monosynaptically connected input neurons and mapped their distribution using an MRI-based volumetric atlas and a novel image alignment and visualization tool that efficiently translates the positions of neurons captured in conventional photomicrographs to Cartesian coordinates...
2017: Frontiers in Neural Circuits
https://www.readbyqxmd.com/read/28298302/visual-and-presaccadic-activity-in-area-8ar-of-the-macaque-monkey-lateral-prefrontal-cortex
#12
Kelly R Bullock, Florian Pieper, Adam J Sachs, Julio C Martinez-Trujillo
Common trends observed in many visual and oculomotor-related cortical areas include retinotopically organized receptive and movement fields exhibiting a Gaussian shape and increasing size with eccentricity. These trends are demonstrated in the frontal eye fields (FEF), many visual areas, and the superior colliculus (SC), but have not been thoroughly characterized in prearcuate area 8Ar of the prefrontal cortex. This is important since area 8Ar, located anterior to the FEF, is more cytoarchitectonically similar to prefrontal areas than premotor areas...
March 15, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28286472/deafferentation-of-the-superior-colliculus-abolishes-spatial-summation-of-redundant-visual-signals
#13
Martijn van Koningsbruggen, Kristin Koller, Robert D Rafal
Two visual signals appearing simultaneously are detected more rapidly than either signal appearing alone. Part of this redundant target effect (RTE) can be attributed to neural summation that has been proposed to occur in the superior colliculus (SC). We report direct evidence in two neurological patients for neural summation in the SC, and that it is mediated by afferent visual information transmitted through its brachium. The RTE was abolished in one patient with a hemorrhage involving the right posterior thalamus that damaged part of the SC and that disrupted its brachium; and in another patient in whom the SC appeared intact but deafferented due to traumatic avulsion of its brachium...
2017: Frontiers in Systems Neuroscience
https://www.readbyqxmd.com/read/28261046/fast-detector-first-responder-interactions-between-the-superior-colliculus-pulvinar-pathway-and-stimuli-relevant-to-primates
#14
REVIEW
Sandra C Soares, Rafael S Maior, Lynne A Isbell, Carlos Tomaz, Hisao Nishijo
Primates are distinguished from other mammals by their heavy reliance on the visual sense, which occurred as a result of natural selection continually favoring those individuals whose visual systems were more responsive to challenges in the natural world. Here we describe two independent but also interrelated visual systems, one cortical and the other subcortical, both of which have been modified and expanded in primates for different functions. Available evidence suggests that while the cortical visual system mainly functions to give primates the ability to assess and adjust to fluid social and ecological environments, the subcortical visual system appears to function as a rapid detector and first responder when time is of the essence, i...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28242738/neuronal-control-of-fixation-and-fixational-eye-movements
#15
REVIEW
Richard J Krauzlis, Laurent Goffart, Ziad M Hafed
Ocular fixation is a dynamic process that is actively controlled by many of the same brain structures involved in the control of eye movements, including the superior colliculus, cerebellum and reticular formation. In this article, we review several aspects of this active control. First, the decision to move the eyes not only depends on target-related signals from the peripheral visual field, but also on signals from the currently fixated target at the fovea, and involves mechanisms that are shared between saccades and smooth pursuit...
April 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28242727/models-of-inhibitory-control
#16
REVIEW
Jeffrey D Schall, Thomas J Palmeri, Gordon D Logan
We survey models of response inhibition having different degrees of mathematical, computational and neurobiological specificity and generality. The independent race model accounts for performance of the stop-signal or countermanding task in terms of a race between GO and STOP processes with stochastic finishing times. This model affords insights into neurophysiological mechanisms that are reviewed by other authors in this volume. The formal link between the abstract GO and STOP processes and instantiating neural processes is articulated through interactive race models consisting of stochastic accumulator GO and STOP units...
April 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28242726/mechanisms-of-saccade-suppression-revealed-in-the-anti-saccade-task
#17
REVIEW
Brian C Coe, Douglas P Munoz
The anti-saccade task has emerged as an important tool for investigating the complex nature of voluntary behaviour. In this task, participants are instructed to suppress the natural response to look at a peripheral visual stimulus and look in the opposite direction instead. Analysis of saccadic reaction times (SRT: the time from stimulus appearance to the first saccade) and the frequency of direction errors (i.e. looking toward the stimulus) provide insight into saccade suppression mechanisms in the brain. Some direction errors are reflexive responses with very short SRTs (express latency saccades), while other direction errors are driven by automated responses and have longer SRTs...
April 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28239342/informative-cues-facilitate-saccadic-localization-in-blindsight-monkeys
#18
Masatoshi Yoshida, Ziad M Hafed, Tadashi Isa
Patients with damage to the primary visual cortex (V1) demonstrate residual visual performance during laboratory tasks despite denying having a conscious percept. The mechanisms behind such performance, often called blindsight, are not fully understood, but the use of surgically-induced unilateral V1 lesions in macaque monkeys provides a useful animal model for exploring such mechanisms. For example, V1-lesioned monkeys localize stimuli in a forced-choice condition while at the same time failing to report awareness of identical stimuli in a yes-no detection condition, similar to human patients...
2017: Frontiers in Systems Neuroscience
https://www.readbyqxmd.com/read/28228585/fixation-target-representation-in-prefrontal-cortex-during-the-anti-saccade-task
#19
Xin Zhou, Christos Constantinidis
Neurons that discharge strongly during the time period of fixation of a visual target and cease to discharge prior to saccade initiation have been described in the brain stem, superior colliculus, and cortical areas. In subcortical structures, fixation neurons play a reciprocal role with saccadic neurons during the generation of eye movements. Their role in the dorsolateral prefrontal cortex is less obvious and it is not known if they are activated by fixation, inhibit saccade generation, or play a role in more complex functions such as the inhibition of inappropriate responses...
February 22, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28228269/diverse-central-projection-patterns-of-retinal-ganglion-cells
#20
Emily M Martersteck, Karla E Hirokawa, Mariah Evarts, Amy Bernard, Xin Duan, Yang Li, Lydia Ng, Seung W Oh, Benjamin Ouellette, Joshua J Royall, Michelle Stoecklin, Quanxin Wang, Hongkui Zeng, Joshua R Sanes, Julie A Harris
Understanding how >30 types of retinal ganglion cells (RGCs) in the mouse retina each contribute to visual processing in the brain will require more tools that label and manipulate specific RGCs. We screened and analyzed retinal expression of Cre recombinase using 88 transgenic driver lines. In many lines, Cre was expressed in multiple RGC types and retinal cell classes, but several exhibited more selective expression. We comprehensively mapped central projections from RGCs labeled in 26 Cre lines using viral tracers, high-throughput imaging, and a data processing pipeline...
February 21, 2017: Cell Reports
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