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Michael Ariel - One of the best experts on this subject based on the ideXlab platform.

  • Shunting Inhibition in Accessory Optic System Neurons
    Journal of neurophysiology, 2004
    Co-Authors: Michael Ariel, Naoki Kogo
    Abstract:

    The interaction of excitatory and inhibitory inputs to the accessory Optic System was studied with whole cell recordings in the turtle basal Optic nucleus. Previous studies have shown that visual p...

  • Connectivity of the turtle accessory Optic System.
    Brain research, 2003
    Co-Authors: Amy E Weber, John R. Martin, Michael Ariel
    Abstract:

    Recent whole-cell recordings show that there are multiple synaptic inputs to the accessory Optic System of the pond turtle Pseudemys scripta elegans (the basal Optic nucleus, BON), suggesting a complex role in visual processing. The BON outputs have now been investigated using transport of diI, rhodamine-conjugated and biotinylated dextrans. Although transport was primarily anterograde, contralateral retinal ganglion cells were labeled retrogradely, confirming that the injection site was a retinal target. Other retrogradely labeled neurons were found ipsilateral to the injection site, in the pretectum, the ventral tegmentum, the dorsal nucleus of the posterior commissure and the lateral habenular nucleus. However, other data indicate that the habenular cells were labeled by spread of the tracer from the BON to the adjacent fasciculus retroflexus and interpeduncular nucleus. Anterogradely labeled fibers projected from BON following three paths, a lateral bundle to the ipsilateral dorsal midbrain, an intermediate bundle to the ipsilateral pretectal area or the posterior commissure and a ventral fiber bundle to the tegmentum bilaterally. Some of these fibers projected caudally through the tegmentum and cerebellar peduncle to terminate just below the Purkinje cell layer of the cerebellar cortex. Fibers that coursed via the intermediate bundle to the posterior commissure were also seen reaching the contralateral pretectal area and the contralateral BON. Injections of the retrograde tracer Fluorogold were also made in the BON to confirm the reciprocal connectivity of both basal Optic nuclei. The pathways revealed by these experiments indicate the existence of multiple afferent and efferent connections of the BON, supporting the view that the accessory Optic System is more than a simple relay of retinal signals into the brainstem for optokinetic reflexes.

  • Morphology of the turtle accessory Optic System
    Visual neuroscience, 2003
    Co-Authors: John R. Martin, Tian Xing Fan, Naoki Kogo, Michael Ariel
    Abstract:

    Neural signals of the moving visual world are detected by a subclass of retinal ganglion cells that project to the accessory Optic System in the vertebrate brainstem. We studied the dendritic morphologies and direction tuning of these brainstem neurons in turtle (Pseudemys scripta elegans) to understand their role in visual processing. Full-field checkerboard patterns were drifted on the contralateral retina while whole-cell recordings were made in the basal Optic nucleus in an intact brainstem preparation in vitro. Neurobiotin diffused into the neurons during the recording and was subsequently localized in brain sections. Neuronal morphologies were traced using appropriate computer software to analyze their position in the brainstem. Most labeled neurons were fusiform in shape and had numerous varicosities along their processes. The majority of dendritic trees spread out in a transverse plane perpendicular to the rostrocaudal axis of the nucleus. Neurons near the brainstem surface were often oriented tangential to that surface, whereas more cells at the dorsal side of the nucleus were oriented radial to the brainstem surface. Further analysis of Nissl-stained neurons revealed the largest neurons are located in the rostral and medial portions of the nucleus although neurons are most densely packed in the middle of the nucleus. The preferred directions of the visual responses of the neurons in this sample did not correlate with their morphology and position in the nucleus. Therefore, the morphology of the cells in the turtle accessory Optic System appears dependent on its position within the nucleus while its visual responses may depend on the synaptic inputs that contact each cell.

  • Synaptic pharmacology in the turtle accessory Optic System.
    Experimental brain research, 2002
    Co-Authors: Naoki Kogo, Tian Xing Fan, Michael Ariel
    Abstract:

    The accessory Optic System of the turtle (the basal Optic nucleus, BON) receives both excitatory and inhibitory inputs that are direction-sensitive. When the dorsal midbrain is ablated, only the monosynaptic direction-sensitive input from the retina to the BON remains. To better understand the central visual processing performed by the accessory Optic System, this study identifies the neurotransmitters and their receptors that mediate the synaptic excitation and inhibition of BON cells. We used a reduced in vitro turtle brainstem preparation in which the two eyes and brain were isolated pharmacologically. Patch recordings were made on BON neurons while drugs were applied to the brain, with the eyes bathed in control media and either exposed to visual pattern motion or subjected to electrical stimulation. An antagonist of the AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) subtype of glutamate receptor applied within the brain chamber blocked the visual responses. In response to electrical stimulation both excitatory and inhibitory synaptic events were blocked in BON cells, presumably by blocking direct excitation by retinal ganglion cell axons in the BON and indirect excitation of inhibitory interneurons elsewhere in the brainstem. An NMDA receptor antagonist was ineffective, even when the response was measured in a BON cell depolarized in Mg2+-free media. A GABAA receptor on the BON cell mediates the inhibitory responses to retinal stimulation. Injection of lidocaine into the contralateral eye caused an increase in spontaneous inhibitory post-synaptic potentials (IPSPs), suggesting that a tonic retinal output exists that reduces brainstem inhibition of BON cells. Also, there may be tonic inhibition of an excitatory path to BON neurons from within the brainstem, because bicuculline increased spontaneous excitatory post-synaptic potentials (EPSPs) observed in a BON cell without retinal input. These results indicate that the BON is a site of complex visual processing of competing visual signals and provide insight into how an interaction of excitation and inhibition creates a retinal slip signal in the accessory Optic System.

  • Direction Tuning of Inhibitory Inputs to the Turtle Accessory Optic System
    Journal of neurophysiology, 2001
    Co-Authors: Michael Ariel, Naoki Kogo
    Abstract:

    Neurons in turtle accessory Optic System (basal Optic nucleus, BON) were studied to compare excitatory and inhibitory visual inputs. Using a reduced in vitro brain stem preparation with the eyes at...

Naoki Kogo - One of the best experts on this subject based on the ideXlab platform.

  • Shunting Inhibition in Accessory Optic System Neurons
    Journal of neurophysiology, 2004
    Co-Authors: Michael Ariel, Naoki Kogo
    Abstract:

    The interaction of excitatory and inhibitory inputs to the accessory Optic System was studied with whole cell recordings in the turtle basal Optic nucleus. Previous studies have shown that visual p...

  • Morphology of the turtle accessory Optic System
    Visual neuroscience, 2003
    Co-Authors: John R. Martin, Tian Xing Fan, Naoki Kogo, Michael Ariel
    Abstract:

    Neural signals of the moving visual world are detected by a subclass of retinal ganglion cells that project to the accessory Optic System in the vertebrate brainstem. We studied the dendritic morphologies and direction tuning of these brainstem neurons in turtle (Pseudemys scripta elegans) to understand their role in visual processing. Full-field checkerboard patterns were drifted on the contralateral retina while whole-cell recordings were made in the basal Optic nucleus in an intact brainstem preparation in vitro. Neurobiotin diffused into the neurons during the recording and was subsequently localized in brain sections. Neuronal morphologies were traced using appropriate computer software to analyze their position in the brainstem. Most labeled neurons were fusiform in shape and had numerous varicosities along their processes. The majority of dendritic trees spread out in a transverse plane perpendicular to the rostrocaudal axis of the nucleus. Neurons near the brainstem surface were often oriented tangential to that surface, whereas more cells at the dorsal side of the nucleus were oriented radial to the brainstem surface. Further analysis of Nissl-stained neurons revealed the largest neurons are located in the rostral and medial portions of the nucleus although neurons are most densely packed in the middle of the nucleus. The preferred directions of the visual responses of the neurons in this sample did not correlate with their morphology and position in the nucleus. Therefore, the morphology of the cells in the turtle accessory Optic System appears dependent on its position within the nucleus while its visual responses may depend on the synaptic inputs that contact each cell.

  • Synaptic pharmacology in the turtle accessory Optic System.
    Experimental brain research, 2002
    Co-Authors: Naoki Kogo, Tian Xing Fan, Michael Ariel
    Abstract:

    The accessory Optic System of the turtle (the basal Optic nucleus, BON) receives both excitatory and inhibitory inputs that are direction-sensitive. When the dorsal midbrain is ablated, only the monosynaptic direction-sensitive input from the retina to the BON remains. To better understand the central visual processing performed by the accessory Optic System, this study identifies the neurotransmitters and their receptors that mediate the synaptic excitation and inhibition of BON cells. We used a reduced in vitro turtle brainstem preparation in which the two eyes and brain were isolated pharmacologically. Patch recordings were made on BON neurons while drugs were applied to the brain, with the eyes bathed in control media and either exposed to visual pattern motion or subjected to electrical stimulation. An antagonist of the AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) subtype of glutamate receptor applied within the brain chamber blocked the visual responses. In response to electrical stimulation both excitatory and inhibitory synaptic events were blocked in BON cells, presumably by blocking direct excitation by retinal ganglion cell axons in the BON and indirect excitation of inhibitory interneurons elsewhere in the brainstem. An NMDA receptor antagonist was ineffective, even when the response was measured in a BON cell depolarized in Mg2+-free media. A GABAA receptor on the BON cell mediates the inhibitory responses to retinal stimulation. Injection of lidocaine into the contralateral eye caused an increase in spontaneous inhibitory post-synaptic potentials (IPSPs), suggesting that a tonic retinal output exists that reduces brainstem inhibition of BON cells. Also, there may be tonic inhibition of an excitatory path to BON neurons from within the brainstem, because bicuculline increased spontaneous excitatory post-synaptic potentials (EPSPs) observed in a BON cell without retinal input. These results indicate that the BON is a site of complex visual processing of competing visual signals and provide insight into how an interaction of excitation and inhibition creates a retinal slip signal in the accessory Optic System.

  • Direction Tuning of Inhibitory Inputs to the Turtle Accessory Optic System
    Journal of neurophysiology, 2001
    Co-Authors: Michael Ariel, Naoki Kogo
    Abstract:

    Neurons in turtle accessory Optic System (basal Optic nucleus, BON) were studied to compare excitatory and inhibitory visual inputs. Using a reduced in vitro brain stem preparation with the eyes at...

  • Membrane properties and monosynaptic retinal excitation of neurons in the turtle accessory Optic System.
    Journal of neurophysiology, 1997
    Co-Authors: Naoki Kogo, Michael Ariel
    Abstract:

    Kogo, Naoki and Michael Ariel. Membrane properties and monosynaptic retinal excitation of neurons in the turtle accessory Optic System. J. Neurophysiol. 78: 614–627, 1997. Using an eye-attached iso...

Marise B. Parent - One of the best experts on this subject based on the ideXlab platform.

  • The accessory Optic System contributes to the spatio-temporal tuning of motion-sensitive pretectal neurons.
    Journal of neurophysiology, 2002
    Co-Authors: Nathan A. Crowder, Hugo Lehmann, Marise B. Parent, Douglas R. Wylie
    Abstract:

    The nucleus of the basal Optic root (nBOR) of the accessory Optic System (AOS) and the pretectal nucleus lentiformis mesencephali (LM) are involved in the analysis of Optic flow that results from s...

  • The Accessory Optic System Contributes to the Spatio-Temporal Tuning of Motion-Sensitive Pretectal Neurons
    2002
    Co-Authors: Nathan A. Crowder, Hugo Lehmann, Marise B. Parent, Douglas R. W. Wylie, Nathan A
    Abstract:

    Douglas R.W. Wylie. The accessory Optic System contributes to the spatio-temporal tuning of motion-sensitive pretectal neurons. J Neurophysiol 90: 1140–1151, 2003; 10.1152/jn.00653.2002. The nucleus of the basal Optic root (nBOR) of the accessory Optic System (AOS) and the pretectal nucleus lentiformis mesencephali (LM) are involved in the analysis of Optic flow that results from self-motion and are important for oculomotor control. These neurons have large receptive fields and exhibit direction selectivity to large moving stimuli. In response to drifting sine wave gratings, LM and nBOR neurons are tuned to either low spatial/high temporal frequencies (SF, TF) or high SF/low TF stimuli. Given that velocity � TF/SF, these are referred to as “fast ” and “slow ” neurons, respectively. There is a heavy projection from the AOS to the pretectum, although its function is unknown. We recorded the directional and spatio-temporal tuning of LM units in pigeons before and after nBOR was inactivated by tetrodotoxin injection. After nBOR inactivation, changes in direction preference were observed for only one of 18 LM units. In contrast, the spatiotemporal tuning of LM units was dramatically altered by nBOR inactivation. Two major effects were observed. First, in response to motion in the preferred direction, most (82%) neurons showed a substantially reduced ( � ��67%) excitation to low SF/high TF gratings. Second, in response to motion in the anti-preferred direction, most (63%) neurons showed a dramatically reduced ( � ��78%) inhibition to high SF/low TF gratings. Thus the projection from the nBOR contributes to the spatio-temporal tuning rather than the directional tuning of LM neurons. We propose a descriptive model whereby LM receives inhibitory and excitatory input from “slow ” and “fast ” nBOR neurons, respectively

Nathan A. Crowder - One of the best experts on this subject based on the ideXlab platform.

  • The accessory Optic System contributes to the spatio-temporal tuning of motion-sensitive pretectal neurons.
    Journal of neurophysiology, 2002
    Co-Authors: Nathan A. Crowder, Hugo Lehmann, Marise B. Parent, Douglas R. Wylie
    Abstract:

    The nucleus of the basal Optic root (nBOR) of the accessory Optic System (AOS) and the pretectal nucleus lentiformis mesencephali (LM) are involved in the analysis of Optic flow that results from s...

  • The Accessory Optic System Contributes to the Spatio-Temporal Tuning of Motion-Sensitive Pretectal Neurons
    2002
    Co-Authors: Nathan A. Crowder, Hugo Lehmann, Marise B. Parent, Douglas R. W. Wylie, Nathan A
    Abstract:

    Douglas R.W. Wylie. The accessory Optic System contributes to the spatio-temporal tuning of motion-sensitive pretectal neurons. J Neurophysiol 90: 1140–1151, 2003; 10.1152/jn.00653.2002. The nucleus of the basal Optic root (nBOR) of the accessory Optic System (AOS) and the pretectal nucleus lentiformis mesencephali (LM) are involved in the analysis of Optic flow that results from self-motion and are important for oculomotor control. These neurons have large receptive fields and exhibit direction selectivity to large moving stimuli. In response to drifting sine wave gratings, LM and nBOR neurons are tuned to either low spatial/high temporal frequencies (SF, TF) or high SF/low TF stimuli. Given that velocity � TF/SF, these are referred to as “fast ” and “slow ” neurons, respectively. There is a heavy projection from the AOS to the pretectum, although its function is unknown. We recorded the directional and spatio-temporal tuning of LM units in pigeons before and after nBOR was inactivated by tetrodotoxin injection. After nBOR inactivation, changes in direction preference were observed for only one of 18 LM units. In contrast, the spatiotemporal tuning of LM units was dramatically altered by nBOR inactivation. Two major effects were observed. First, in response to motion in the preferred direction, most (82%) neurons showed a substantially reduced ( � ��67%) excitation to low SF/high TF gratings. Second, in response to motion in the anti-preferred direction, most (63%) neurons showed a dramatically reduced ( � ��78%) inhibition to high SF/low TF gratings. Thus the projection from the nBOR contributes to the spatio-temporal tuning rather than the directional tuning of LM neurons. We propose a descriptive model whereby LM receives inhibitory and excitatory input from “slow ” and “fast ” nBOR neurons, respectively

Hugo Lehmann - One of the best experts on this subject based on the ideXlab platform.

  • The accessory Optic System contributes to the spatio-temporal tuning of motion-sensitive pretectal neurons.
    Journal of neurophysiology, 2002
    Co-Authors: Nathan A. Crowder, Hugo Lehmann, Marise B. Parent, Douglas R. Wylie
    Abstract:

    The nucleus of the basal Optic root (nBOR) of the accessory Optic System (AOS) and the pretectal nucleus lentiformis mesencephali (LM) are involved in the analysis of Optic flow that results from s...

  • The Accessory Optic System Contributes to the Spatio-Temporal Tuning of Motion-Sensitive Pretectal Neurons
    2002
    Co-Authors: Nathan A. Crowder, Hugo Lehmann, Marise B. Parent, Douglas R. W. Wylie, Nathan A
    Abstract:

    Douglas R.W. Wylie. The accessory Optic System contributes to the spatio-temporal tuning of motion-sensitive pretectal neurons. J Neurophysiol 90: 1140–1151, 2003; 10.1152/jn.00653.2002. The nucleus of the basal Optic root (nBOR) of the accessory Optic System (AOS) and the pretectal nucleus lentiformis mesencephali (LM) are involved in the analysis of Optic flow that results from self-motion and are important for oculomotor control. These neurons have large receptive fields and exhibit direction selectivity to large moving stimuli. In response to drifting sine wave gratings, LM and nBOR neurons are tuned to either low spatial/high temporal frequencies (SF, TF) or high SF/low TF stimuli. Given that velocity � TF/SF, these are referred to as “fast ” and “slow ” neurons, respectively. There is a heavy projection from the AOS to the pretectum, although its function is unknown. We recorded the directional and spatio-temporal tuning of LM units in pigeons before and after nBOR was inactivated by tetrodotoxin injection. After nBOR inactivation, changes in direction preference were observed for only one of 18 LM units. In contrast, the spatiotemporal tuning of LM units was dramatically altered by nBOR inactivation. Two major effects were observed. First, in response to motion in the preferred direction, most (82%) neurons showed a substantially reduced ( � ��67%) excitation to low SF/high TF gratings. Second, in response to motion in the anti-preferred direction, most (63%) neurons showed a dramatically reduced ( � ��78%) inhibition to high SF/low TF gratings. Thus the projection from the nBOR contributes to the spatio-temporal tuning rather than the directional tuning of LM neurons. We propose a descriptive model whereby LM receives inhibitory and excitatory input from “slow ” and “fast ” nBOR neurons, respectively