Physiological Properties of Neurons in the Optic Layer of the Rat's Superior Colliculus

Lo, Fu-Sun, R. John Cork, and R. Ranney Mize. Physiological properties of neurons in the optic layer of the rat's superior colliculus. J. Neurophysiol. 80: 331–343, 1998. We made intracellular recordings from 74 neurons in the optic layer of the rat superior colliculus (SC). Resting membrane potentials were −62.3 ± 6.2 (SD) mV, and input resistances were 37.9 ± 10.1 MΩ. Optic layer neurons had large sodium spikes (74.2 ± 12.3 mV) with an overshoot of 12 mV and a half-amplitude duration of 0.75 ± 0.2 ms. Each sodium spike was followed by two afterhyperpolarizations (AHPs), one of short duration and one of longer duration, which were mediated by tetraethylammonium (TEA)-sensitive ( I C) or apamin-sensitive ( I AHP) calcium-activated potassium currents, respectively. Sodium spikes were also followed by an afterdepolarization (ADP), which was only revealed when the AHPs were blocked by TEA or apamin. In response to hyperpolarizing current pulses, optic layer neurons showed an inward rectification mediated by H channels. At the break of the current pulse, there was a rebound low-threshold spike (LTS) with a short duration of <25 ms. The LTS usually induced two sodium spikes (doublet). Most optic layer neurons (84%) behaved as intrinsically bursting cells. They responded to suprathreshold depolarization with an initial burst (or doublet) followed by a train of regular single spikes. The remaining 16% of cells acted as chattering cells with high-frequency gamma (20–80 Hz) rhythmic burst firing within a narrow range of depolarized potentials. The interburst frequency was voltage dependent and also time dependent, i.e., showed frequency adaptation. Unmasking the ADP with either TEA or apamin converted all of the tested intrinsically bursting cells into chattering cells, indicating that the ADP played a crucial role in the generation of rhythmic burst firing. Optic layer neurons receive direct retinal excitation mediated by both N-methyl-d-aspartate (NMDA) and non-NMDA receptors. Optic tract (OT) stimulation also led to γ-aminobutyric acid-A (GABAA) receptor–mediated inhibition, the main effect of which was to curtail the excitatory response to retinal inputs by shunting the excitatory postsynaptic current. Intracellular staining with biocytin showed that the optic layer neurons that we recorded from were mostly either wide-field vertical neurons or other cells with predominately superficially projecting dendrites. These cells were similar to calbindin immunoreactive cells seen in the optic layer. The characteristics of these optic layer neurons, such as prominent AHPs, strong shunting effect of inhibition, and short-lasting LTS, suggest that they respond transiently to retinal inputs. This is consistent with a function for these cells as the first relay station in the extrageniculate visual pathway.

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An adaptive Reichardt detector model of motion adaptation in insects and mammals

Visual Neuroscience ◽

10.1017/s0952523800012694 ◽

1997 ◽

Vol 14 (4) ◽

pp. 741-749 ◽

Cited By ~ 37

Author(s):

Colin W.G. Clifford ◽

Michael R. Ibbotson ◽

Keith Langley

Keyword(s):

Dynamic Range ◽

Frequency Tuning ◽

Temporal Frequency ◽

Optic Tract ◽

Intrinsic Property ◽

Wide Field ◽

Motion Adaptation ◽

Motion Sensitivity ◽

Differential Motion ◽

Motion Detectors

AbstractThere are marked similarities in the adaptation to motion observed in wide-field directional neurons found in the mammalian nucleus of the optic tract and cells in the insect lobula plate. However, while the form and time scale of adaptation is comparable in the two systems, there is a difference in the directional properties of the effect. A model based on the Reichardt detector is proposed to describe adaptation in mammals and insects, with only minor modifications required to account for the differences in directionality. Temporal-frequency response functions of the neurons and the model are shifted laterally and compressed by motion adaptation. The lateral shift enhances dynamic range and differential motion sensitivity. The compression is not caused by fatigue, but is an intrinsic property of the adaptive process resulting from interdependence of temporal-frequency tuning and gain in the temporal filters of the motion detectors.

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BOLD Temporal Dynamics of Rat Superior Colliculus and Lateral Geniculate Nucleus following Short Duration Visual Stimulation

PLoS ONE ◽

10.1371/journal.pone.0018914 ◽

2011 ◽

Vol 6 (4) ◽

pp. e18914 ◽

Cited By ~ 23

Author(s):

Condon Lau ◽

Iris Y. Zhou ◽

Matthew M. Cheung ◽

Kevin C. Chan ◽

Ed X. Wu

Keyword(s):

Superior Colliculus ◽

Lateral Geniculate Nucleus ◽

Short Duration ◽

Temporal Dynamics ◽

Visual Stimulation ◽

Lateral Geniculate

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Effects of norepinephrine upon superficial layer neurons in the superior colliculus of the hamster: In vitro studies

Visual Neuroscience ◽

10.1017/s0952523899163156 ◽

1999 ◽

Vol 16 (3) ◽

pp. 557-570 ◽

Cited By ~ 9

Author(s):

HONGJING TAN ◽

RICHARD D. MOONEY ◽

ROBERT W. RHOADES

Keyword(s):

Superior Colliculus ◽

Optic Tract ◽

Reversal Potential ◽

Outward Current ◽

Input Resistance ◽

Superficial Layer ◽

Membrane Properties ◽

Induced Response

Intracellular recording techniques were used to evaluate the effects of norepinephrine (NE) on the membrane properties of superficial layer (stratum griseum superficiale and stratum opticum) superior colliculus (SC) cells. Of the 207 cells tested, 44.4% (N = 92) were hyperpolarized by ≥3 mV and 8.7% (N = 18) were depolarized by ≥3 mV by application of NE. Hyperpolarization induced by NE was dose dependent (EC50 = 8.1 μM) and was associated with decreased input resistance and outward current which had a reversal potential of −94.0 mV. Depolarization was associated with a very slight rise in input resistance and had a reversal potential of −93.1 mV for the single cell tested. Pharmacologic experiments demonstrated that isoproterenol, dobutamine, and p-aminoclonidine all hyperpolarized SC cells. These results are consistent with the conclusion that NE-induced hyperpolarization of SC cells is mediated by both α2 and β1 adrenoceptors. The α1 adrenoceptor agonists, methoxamine and phenylephrine, depolarized 35% (6 of 17) of the SC cells tested by ≥3 mV. Most of the SC cells tested exhibited responses indicative of expression of more than one adrenoceptor. Application of p-aminoclonidine or dobutamine inhibited transsynaptic responses in SC cells evoked by electrical stimulation of optic tract axons. Inhibition of evoked responses by these agents was usually, but not invariably, associated with a hyperpolarization of the cell membrane and a reduction in depolarizing potentials evoked by application of glutamate. The present in vitro results are consistent with those of the companion in vivo study which suggested that NE-induced response suppression in superficial layer SC neurons was primarily postsynaptic and chiefly mediated by both α2 and β1 adrenoceptors.

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High-energy astrophysics and the search for sources of gravitational waves

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2017.0294 ◽

2018 ◽

Vol 376 (2120) ◽

pp. 20170294 ◽

Cited By ~ 1

Author(s):

P. T. O'Brien ◽

P. Evans

Keyword(s):

Gravitational Wave ◽

Short Duration ◽

Gamma Ray ◽

New Technology ◽

High Energy ◽

Compact Objects ◽

Wide Field ◽

High Energy Radiation ◽

Energy Radiation ◽

Binary Mergers

The dawn of the gravitational-wave (GW) era has sparked a greatly renewed interest into possible links between sources of high-energy radiation and GWs. The most luminous high-energy sources—gamma-ray bursts (GRBs)—have long been considered as very likely sources of GWs, particularly from short-duration GRBs, which are thought to originate from the merger of two compact objects such as binary neutron stars and a neutron star–black hole binary. In this paper, we discuss: (i) the high-energy emission from short-duration GRBs; (ii) what other sources of high-energy radiation may be observed from binary mergers; and (iii) how searches for high-energy electromagnetic counterparts to GW events are performed with current space facilities. While current high-energy facilities, such as Swift and Fermi, play a crucial role in the search for electromagnetic counterparts, new space missions will greatly enhance our capabilities for joint observations. We discuss why such facilities, which incorporate new technology that enables very wide-field X-ray imaging, are required if we are to truly exploit the multi-messenger era. This article is part of a discussion meeting issue ‘The promises of gravitational-wave astronomy’.

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Physiological Properties of Central Medial and Central Lateral Amygdala Neurons

Journal of Neurophysiology ◽

10.1152/jn.1999.82.4.1843 ◽

1999 ◽

Vol 82 (4) ◽

pp. 1843-1854 ◽

Cited By ~ 38

Author(s):

Marzia Martina ◽

Sébastien Royer ◽

Denis Paré

Keyword(s):

Conditioned Fear ◽

Brain Slices ◽

Cell Types ◽

Membrane Depolarization ◽

Membrane Properties ◽

Repetitive Firing ◽

Inward Rectification ◽

Current Pulses ◽

Outward Rectification ◽

Physiological Properties

Mounting evidence implicates the central (CE) nucleus of the amygdala in the mediation of classically conditioned fear responses. However, little data are available regarding the intrinsic membrane properties of CE amygdala neurons. Here, we characterized the physiological properties of CE medial (CEM) and CE lateral (CEL) amygdala neurons using whole cell recordings in brain slices maintained in vitro. Several classes of CE neurons were distinguished on the basis of their physiological properties. Most CEM cells (95%), here termed “late-firing neurons,” displayed a marked voltage- and time-dependent outward rectification in the depolarizing direction. This phenomenon was associated with a conspicuous delay between the onset of depolarizing current pulses and the first action potential. During this delay, the membrane potential ( V m) depolarized slowly, the steepness of this depolarizing ramp increasing as the prepulse V m was hyperpolarized from −60 to −90 mV. Low extracellular concentrations of 4-aminopyridine (30 μM) reversibly abolished the outward rectification and the delay to firing. Late-firing CEM neurons displayed a continuum of repetitive firing properties with cells generating single spikes at one pole and high-frequency (≥90 Hz) spike bursts at the other. In contrast, only 56% of CEL cells displayed the late-firing behavior prevalent among CEM neurons. Moreover, these CEL neurons only generated single spikes in response to membrane depolarization. A second major class of CEL cells (38%) lacked the characteristic delay to firing observed in CEM cells, generated single spikes in response to membrane depolarization, and displayed various degrees of inward rectification in the hyperpolarizing direction. In both regions of the CE nucleus, two additional cell types were encountered infrequently (≤ 6% of our samples). One type of neurons, termed “low-threshold bursting cells” had a behavior reminiscent of thalamocortical neurons. The second type of cells, called “fast-spiking cells,” generated brief action potentials at high rates with little spike frequency adaptation in response to depolarizing current pulses. These findings indicate that the CE nucleus contains several types of neurons endowed with distinct physiological properties. Moreover, these various cell types are not distributed uniformly in the medial and lateral sector of the CE nucleus. This heterogeneity parallels anatomic data indicating that these subnuclei are part of different circuits.

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Retinal Projections in the Northern Native Cat, Dasyurus-Hallucatus (Marsupialia, Dasyuridae)

Australian Journal of Zoology ◽

10.1071/zo9870115 ◽

1987 ◽

Vol 35 (2) ◽

pp. 115 ◽

Cited By ~ 3

Author(s):

AM Harman ◽

DP Crewther ◽

JE Nelson ◽

SG Crewther

Keyword(s):

Superior Colliculus ◽

Lateral Geniculate Nucleus ◽

Optic Tract ◽

Dorsal Lateral Geniculate Nucleus ◽

Accessory Optic System ◽

Anterograde Transport ◽

Retinal Projections ◽

Lateral Geniculate ◽

Contralateral Eye ◽

Dorsal Lateral Geniculate

The retinal projections of the northern native cat, Dasyurus hallucatus, were studied by the anterograde transport of tritiated proline and by autoradiography. Seven regions in the brain were found to receive direct retinal projections: (1) the suprachiasmatic nucleus; (2) the dorsal lateral geniculate nucleus; (3) the ventral lateral geniculate nucleus; (4) the lateral posterior nucleus; (5) the nuclei of the accessory optic tract; (6) the pretectal nuclei; (7) the superior colliculus. All nuclei studied received a bilateral retinal projection except the medial terminal nucleus of the accessory optic system, in which only a contralateral input was found. The contralateral eye had a greater input in all cases. As with the related species, Dasyurus viverrinus, there is extensive binocular overlap in the dorsal lateral geniculate nucleus (LGNd). In the LGNd contralateral to the injected eye, the autoradiographs show four contralateral terminal bands occupying most of the nucleus. The axonal terminations in the ipsilateral LGNd are more diffuse but show a faint lamination pattern of four bands. The ventral portion of the LGNd receives only contralateral retinal input, and therefore probably represents the monocular visual field. The other principal termination of the optic nerve, the superior colliculus, has a predominantly contralateral input to both sublayers of the stratum griseum superficiale. However, the ipsilateral fibres terminate only in patches in the more inferior sublayer.

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Wide-field nondirectional visual units in the pretectum: do they suppress ocular following of saccade-induced visual stimulation

Journal of Neurophysiology ◽

10.1152/jn.1994.72.3.1448 ◽

1994 ◽

Vol 72 (3) ◽

pp. 1448-1450 ◽

Cited By ~ 13

Author(s):

M. R. Ibbotson ◽

R. F. Mark

Keyword(s):

Visual Stimulation ◽

Receptive Fields ◽

Optic Tract ◽

Inhibitory Input ◽

Wide Field ◽

Retinal Slip ◽

Spatial Frequencies ◽

Spontaneous Activities ◽

Ocular Following ◽

Temporal Stimuli

1. Direction-selective neurons in the nucleus of the optic tract (NOT) provide motion signals for controlling ocular following responses. When stimulated at low temporal and high spatial frequencies of motion (slow speeds), these retinal-slip neurons produce directional responses. When stimulated by motion at high temporal and low spatial frequencies (the visual conditions during saccades) the spontaneous activities of the neurons are inhibited by motion in all directions. A second class of neurons in, or near, the NOT have large receptive fields, are nondirectional, and are tuned to detect the same spatial and temporal stimuli that induce nondirectional inhibition in the retinal-slip neurons. We suggest that the nondirectional cells provide an inhibitory input for the retinal-slip neurons and therefore prevent ocular following of the visual displacements that accompany saccades.

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New Mechanism That Accounts for Position Sensitivity of Saccades Evoked in Response to Stimulation of Superior Colliculus

Journal of Neurophysiology ◽

10.1152/jn.1998.80.6.3373 ◽

1998 ◽

Vol 80 (6) ◽

pp. 3373-3379 ◽

Cited By ~ 15

Author(s):

A. K. Moschovakis ◽

Y. Dalezios ◽

J. Petit ◽

A. A. Grantyn

Keyword(s):

Electrical Stimulation ◽

Eye Movements ◽

Superior Colliculus ◽

Short Duration ◽

High Frequency ◽

Initial Position ◽

Characteristic Vector ◽

Extraocular Motoneurons ◽

Position Sensitivity ◽

Stimulation Of

Moschovakis, A. K., Y. Dalezios, J. Petit, and A. A. Grantyn. New mechanism that accounts for position sensitivity of saccades evoked in response to stimulation of superior colliculus. J. Neurophysiol. 80: 3373–3379, 1998. Electrical stimulation of the feline superior colliculus (SC) is known to evoke saccades whose size depends on the site stimulated (the “characteristic vector” of evoked saccades) and the initial position of the eyes. Similar stimuli were recently shown to produce slow drifts that are presumably caused by relatively direct projections of the SC onto extraocular motoneurons. Both slow and fast evoked eye movements are similarly affected by the initial position of the eyes, despite their dissimilar metrics, kinematics, and anatomic substrates. We tested the hypothesis that the position sensitivity of evoked saccades is due to the superposition of largely position-invariant saccades and position-dependent slow drifts. We show that such a mechanism can account for the fact that the position sensitivity of evoked saccades increases together with the size of their characteristic vector. Consistent with it, the position sensitivity of saccades drops considerably when the contribution of slow drifts is minimal as, for example, when there is no overlap between evoked saccades and short-duration trains of high-frequency stimuli.

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