Pathways and polarities of synaptic interactions in the inner retina of the mudpuppy: II. Insight revealed by an analysis of latency and threshold

γ-Aminobutyric acid (GABA) receptors on retinal bipolar cells (BCs) are highly relevant to spatial and temporal integration of visual signals in the outer and inner retina. In the present work, subcellular localization and complements of GABAA and GABACreceptors on BCs were investigated by whole cell recordings and local drug application via multi-barreled puff pipettes in the bullfrog retinal slice preparation. Four types of the BCs (types 1–4) were identified morphologically by injection of Lucifer yellow. According to the ramification levels of the axon terminals and the responses of these cells to glutamate (or kainate) applied at their dendrites, types 1 and 2 of BCs were supposed to be off type, whereas types 3 and 4 of BCs might be on type. Bicuculline (BIC), a GABAA receptor antagonist, and imidazole-4-acetic acid (I4AA), a GABAC receptor antagonist, were used to distinguish GABA receptor-mediated responses. In all BCs tested, not only the axon terminals but also the dendrites showed high GABA sensitivity mediated by both GABAA and GABACreceptors. Subcellular localization and complements of GABAA and GABAC receptors at the dendrites and axon terminals were highly related to the dichotomy of offand on BCs. In the case of off BCs, GABAA receptors were rather evenly distributed at the dendrites and axon terminals, but GABAC receptors were predominantly expressed at the axon terminals. Moreover, the relative contribution of GABAC receptors to the axon terminals was prevalent over that of GABAA receptors, while the situation was reversed at the dendrites. In the case of on BCs, GABAA and GABAC receptors both preferred to be expressed at the axon terminals; relative contributions of these two GABA receptor subtypes to both the sites were comparable, while GABAC receptors were much less expressed than GABAA receptors. GABAA, but not GABAC receptors, were expressed clusteringly at axons of a population of BCs. In a minority of BCs, I4AA suppressed the GABAC responses at the dendrites, but not at the axon terminal, implying that the GABAC receptors at these two sites may be heterogeneous. Taken together, these results suggest that GABAA and GABAC receptors may play different roles in the outer and inner retina and the differential complements of the two receptors on off and on BCs may be closely related to physiological functions of these cells.

Download Full-text

Thickness mapping of the inner retina by spectral-domain optical coherence tomography in an N-methyl-d-aspartate-induced retinal damage model

Experimental Eye Research ◽

10.1016/j.exer.2013.05.009 ◽

2013 ◽

Vol 113 ◽

pp. 19-25 ◽

Cited By ~ 5

Author(s):

Yuta Ohno ◽

Shuichi Makita ◽

Masamitsu Shimazawa ◽

Kazuhiro Tsuruma ◽

Yoshiaki Yasuno ◽

...

Keyword(s):

Optical Coherence Tomography ◽

Damage Model ◽

Spectral Domain ◽

Retinal Damage ◽

Optical Coherence ◽

Inner Retina

Download Full-text

Population dynamics of the modified theta model: macroscopic phase reduction and bifurcation analysis link microscopic neuronal interactions to macroscopic gamma oscillation

Journal of The Royal Society Interface ◽

10.1098/rsif.2014.0058 ◽

2014 ◽

Vol 11 (95) ◽

pp. 20140058 ◽

Cited By ~ 25

Author(s):

Kiyoshi Kotani ◽

Ikuhiro Yamaguchi ◽

Lui Yoshida ◽

Yasuhiko Jimbo ◽

G. Bard Ermentrout

Keyword(s):

Bifurcation Analysis ◽

Field Potential ◽

Reversal Potential ◽

Planck Equation ◽

Gamma Oscillations ◽

Gamma Oscillation ◽

Synaptic Coupling ◽

Time Constants ◽

Shunting Inhibition ◽

Synaptic Interactions

Gamma oscillations of the local field potential are organized by collective dynamics of numerous neurons and have many functional roles in cognition and/or attention. To mathematically and physiologically analyse relationships between individual inhibitory neurons and macroscopic oscillations, we derive a modification of the theta model, which possesses voltage-dependent dynamics with appropriate synaptic interactions. Bifurcation analysis of the corresponding Fokker–Planck equation (FPE) enables us to consider how synaptic interactions organize collective oscillations. We also develop the adjoint method (infinitesimal phase resetting curve) for simultaneous equations consisting of ordinary differential equations representing synaptic dynamics and a partial differential equation for determining the probability distribution of the membrane potential. This method provides a macroscopic phase response function (PRF), which gives insights into how it is modulated by external perturbation or internal changes of parameters. We investigate the effects of synaptic time constants and shunting inhibition on these gamma oscillations. The sensitivity of rising and decaying time constants is analysed in the oscillatory parameter regions; we find that these sensitivities are not largely dependent on rate of synaptic coupling but, rather, on current and noise intensity. Analyses of shunting inhibition reveal that it can affect both promotion and elimination of gamma oscillations. When the macroscopic oscillation is far from the bifurcation, shunting promotes the gamma oscillations and the PRF becomes flatter as the reversal potential of the synapse increases, indicating the insensitivity of gamma oscillations to perturbations. By contrast, when the macroscopic oscillation is near the bifurcation, shunting eliminates gamma oscillations and a stable firing state appears. More interestingly, under appropriate balance of parameters, two branches of bifurcation are found in our analysis of the FPE. In this case, shunting inhibition can effect both promotion and elimination of the gamma oscillation depending only on the reversal potential.

Download Full-text

GABAergic synaptic interactions in the substantia nigra

Brain Research ◽

10.1016/0006-8993(93)91095-a ◽

1993 ◽

Vol 617 (2) ◽

pp. 274-284 ◽

Cited By ~ 21

Author(s):

I. Mendez ◽

K. Elisevich ◽

B.A. Flumerfelt

Keyword(s):

Substantia Nigra ◽

Synaptic Interactions

Download Full-text

POSTOPERATIVE RESTORATION OF FOVEAL INNER RETINAL CONFIGURATION IN PATIENTS WITH EPIRETINAL MEMBRANE AND ABNORMALLY THICK INNER RETINA

Retina ◽

10.1097/iae.0000000000000276 ◽

2015 ◽

Vol 35 (1) ◽

pp. 111-119 ◽

Cited By ~ 21

Author(s):

Hyun Seung Yang ◽

Jee Taek Kim ◽

Soo Geun Joe ◽

Joo Yong Lee ◽

Young Hee Yoon

Keyword(s):

Epiretinal Membrane ◽

Inner Retina

Download Full-text

DEVELOPMENT OF FEEDFORWARD RECEPTIVE FIELD STRUCTURE OF A SIMPLE CELL AND ITS CONTRIBUTION TO THE ORIENTATION SELECTIVITY: A MODELING STUDY

International Journal of Neural Systems ◽

10.1142/s0129065705000104 ◽

2005 ◽

Vol 15 (01n02) ◽

pp. 55-70 ◽

Cited By ~ 1

Author(s):

AKHIL R GARG ◽

KLAUS OBERMAYER ◽

BASABI BHAUMIK

Keyword(s):

Receptive Field ◽

Field Structure ◽

Orientation Selectivity ◽

Simple Cell ◽

Homogeneous State ◽

Synaptic Efficacy ◽

Synaptic Interactions ◽

Experimental Findings ◽

Modeling Study

Recent experimental studies of hetero-synaptic interactions in various systems have shown the role of signaling in the plasticity, challenging the conventional understanding of Hebb's rule. It has also been found that activity plays a major role in plasticity, with neurotrophins acting as molecular signals translating activity into structural changes. Furthermore, role of synaptic efficacy in biasing the outcome of competition has also been revealed recently. Motivated by these experimental findings we present a model for the development of simple cell receptive field structure based on the competitive hetero-synaptic interactions for neurotrophins combined with cooperative hetero-synaptic interactions in the spatial domain. We find that with proper balance in competition and cooperation, the inputs from two populations (ON/OFF) of LGN cells segregate starting from the homogeneous state. We obtain segregated ON and OFF regions in simple cell receptive field. Our modeling study supports the experimental findings, suggesting the role of synaptic efficacy and the role of spatial signaling. We find that using this model we obtain simple cell RF, even for positively correlated activity of ON/OFF cells. We also compare different mechanism of finding the response of cortical cell and study their possible role in the sharpening of orientation selectivity. We find that degree of selectivity improvement in individual cells varies from case to case depending upon the structure of RF field and type of sharpening mechanism.

Download Full-text

Impulse Identification and Axon Mapping of the Nine Neurons in the Cardiac Ganglion of the Lobster Homarus Americanus

Journal of Experimental Biology ◽

10.1242/jeb.47.2.327 ◽

1967 ◽

Vol 47 (2) ◽

pp. 327-341

Author(s):

DANIEL K. HARTLINE

Keyword(s):

Large Cell ◽

Homarus Americanus ◽

Simultaneous Recording ◽

Small Cell ◽

Complete Analysis ◽

Cardiac Ganglion ◽

Cell Identification ◽

Cell Axon ◽

Synaptic Interactions ◽

Stimulation Of

1. Simultaneous recording from several pairs of electrodes placed along the ganglion and certain efferent nerves, during stimulation of other efferents, allows the course of antidromic impulses in each stimulated axon to be mapped. 2. These impulses disappear as they approach their somata, being incapable of invading them, a fact which permits identification of a particular efferent axon with a particular soma. 3. By these means the courses of all such efferent axons, and their corresponding somata, have been determined. These all belong to the five large cells. 4. The impulses from each such axon occurring during the spontaneous burst can be identified, as can impulses from each small cell. 5. Each large-cell axon appears to be inexcitable until it is a few mm from the soma. 6. If the axon branches within this inexcitable region, the branches tend to fire impulses independently. 7. The technique of cell identification opens the way to a more complete analysis of the ganglion's activity and the synaptic interactions which produce it.

Download Full-text

Synaptic Interactions Between Thalamic and Cortical Inputs Onto Cortical Neurons In Vivo

Journal of Neurophysiology ◽

10.1152/jn.01105.2003 ◽

2004 ◽

Vol 91 (5) ◽

pp. 1990-1998 ◽

Cited By ~ 22

Author(s):

Pablo Fuentealba ◽

Sylvain Crochet ◽

Igor Timofeev ◽

Mircea Steriade

Keyword(s):

Cortical Neurons ◽

Time Course ◽

Input Resistance ◽

Maximal Effect ◽

Time Intervals ◽

Neocortical Neurons ◽

Synaptic Interactions ◽

Cortical Responses ◽

Cortical Inputs

To study the interactions between thalamic and cortical inputs onto neocortical neurons, we used paired-pulse stimulation (PPS) of thalamic and cortical inputs as well as PPS of two cortical or two thalamic inputs that converged, at different time intervals, onto intracellularly recorded cortical and thalamocortical neurons in anesthetized cats. PPS of homosynaptic cortico-cortical pathways produced facilitation, depression, or no significant effects in cortical pathways, whereas cortical responses to thalamocortical inputs were mostly facilitated at both short and long intervals. By contrast, heterosynaptic interactions between either cortical and thalamic, or thalamic and cortical, inputs generally produced decreases in the peak amplitudes and depolarization area of evoked excitatory postsynaptic potentials (EPSPs), with maximal effect at ∼10 ms and lasting from 60 to 100 ms. All neurons tested with thalamic followed by cortical stimuli showed a decrease in the apparent input resistance ( Rin), the time course of which paralleled that of decreased responses, suggesting that shunting is the factor accounting for EPSP's decrease. Only half of neurons tested with cortical followed by thalamic stimuli displayed changes in Rin. Spike shunting in the thalamus may account for those cases in which decreased synaptic responsiveness of cortical neurons was not associated with decreased Rin because thalamocortical neurons showed decreased firing probability during cortical stimulation. These results suggest a short-lasting but strong shunting between thalamocortical and cortical inputs onto cortical neurons.

Download Full-text