scholarly journals Modulation of the vesicle code transmitting the visual signal in the retina

2020 ◽  
Author(s):  
José Moya-Díaz ◽  
Ben James ◽  
Leon Lagnado
Keyword(s):  
Substance P ◽  
Visual Information ◽  
Calcium Influx ◽  
Calcium Transient ◽  
Bipolar Cells ◽  
Visual Signals ◽  
Visual Signal ◽  
Temporal Precision ◽  
Low Pass ◽  
Presynaptic Calcium

SummaryMultivesicular release (MVR) allows retinal bipolar cells to transmit visual signals as changes in both the rate and amplitude of synaptic events. How do neuromodulators reguate this vesicle code? By imaging larval zebrafish, we find that the variability of calcium influx is a major source of synaptic noise. Dopamine increases synaptic gain up to 15-fold while Substance P reduces it 7-fold, both by acting on the presynaptic calcium transient to alter the distribution of amplitudes of multivesicular events. An increase in gain is accompanied by a decrease in the temporal precision of transmission and a reduction in the efficiency with which vesicles transfer visual information. The decrease in gain caused by Substance P was also associated with a shift in temporal filtering from band-pass to low-pass. This study demonstrates how neuromodulators act on the synaptic transformation of the visual signal to alter the way information is coded with vesicles.

scholarly journals An amplitude code increases the efficiency of information transmission across a visual synapse

2018 ◽  
Author(s):  
Ben James ◽  
Léa Darnet ◽  
José Moya-Díaz ◽  
Sofie-Helene Seibel ◽  
Leon Lagnado
Keyword(s):  
Synaptic Vesicles ◽  
Visual Information ◽  
Dynamic Range ◽  
Bipolar Cells ◽  
Visual Signals ◽  
Temporal Precision ◽  
Ribbon Synapses ◽  
Analogue Signals ◽  
Rate Coding ◽  
The Brain

Most neurons in the brain transmit information digitally using sequences of spikes that trigger release of synaptic vesicles of fixed size. The first stages of vision and hearing are distinct in operating with analogue signals, but it is unclear how these are recoded for synaptic transmission. By imaging the release of glutamate in live zebrafish, we demonstrate how ribbon synapses of retinal bipolar cells transmit analogue visual signals by changes in both the rate and amplitude of synaptic events. Higher contrasts released glutamate packets composed of more vesicles and coding by amplitude often continued after rate coding had saturated. Glutamate packets equivalent to five vesicles transmitted four times as many bits of information per vesicle compared to independent release events. By discretizing analogue signals into sequences of numbers ranging up to eleven, ribbon synapses increase the dynamic range, temporal precision and efficiency with which visual information is transmitted.

Presynaptic Ca2+ Influx at the Inhibitor of the Crayfish Neuromuscular Junction: A Photometric Study at a High Time Resolution

2000 ◽  
Vol 83 (1) ◽  
pp. 552-562 ◽  
Author(s):  
Andrey Vyshedskiy ◽  
Jen-Wei Lin
Keyword(s):  
Action Potential ◽  
Time Resolution ◽  
Transmitter Release ◽  
Calcium Influx ◽  
Calcium Transient ◽  
High Time ◽  
High Time Resolution ◽  
Presynaptic Calcium ◽  
Crayfish Neuromuscular Junction ◽  
Fluorescence Transients

Presynaptic calcium influx at the inhibitor of the crayfish neuromuscular junction was investigated by measuring fluorescence transients generated by calcium-sensitive dyes. This approach allowed us to correlate presynaptic calcium influx with transmitter release at a high time resolution. Systematic testing of the calcium indicators showed that only low-affinity dyes, with affinities in the range of micromolar, should be used to avoid saturation of dye binding and interference with transmitter release. Presynaptic calcium influx was regulated by slowly increasing the duration of the action potential through progressive block of potassium channels. The amplitude of the calcium transient, measured from a cluster of varicosities, was linearly related to the duration of the action potential with a slope of 1.2. Gradual changes in potassium channel block allowed us to estimate the calcium cooperativity of transmitter release over a 10-fold range in presynaptic calcium influx. Calcium cooperativity measured here exhibited one component with an average value of 3.1. Inspection of simultaneously recorded presynaptic calcium transients and inhibitory postsynaptic currents (IPSCs) showed that prolonged action potentials were associated with a slow rising phase of presynaptic calcium transients, which were matched by a slow rate of rise of IPSCs. The close correlation suggests that fluorescence transients provide information on the rate of calcium influx. Because there is an anatomic mismatch between the presynaptic calcium transient, measured from a cluster of varicosities, and IPSC, measured with two-electrode voltage clamp, macropatch recording was used to monitor inhibitory postsynaptic responses from the same cluster of varicosities from which the calcium transient was measured. Inhibitory postsynaptic responses recorded with the macropatch method exhibited a faster rising phase than that recorded with two-electrode voltage clamp. This difference could be attributed to slight asynchrony of transmitter release due to action potential conduction along fine branches. In conclusion, this report shows that fluorescence transients generated by calcium-sensitive dyes can provide insights to the properties of presynaptic calcium influx, and its correlation with transmitter release, at a high time resolution.

Temporal Modulation of Scotopic Visual Signals by A17 Amacrine Cells in Mammalian Retina In Vivo

2003 ◽  
Vol 89 (4) ◽  
pp. 2159-2166 ◽  
Author(s):  
Cun-Jian Dong ◽  
William A. Hare
Keyword(s):  
Light Intensity ◽  
Visual Information ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Visual Signals ◽  
Temporal Properties ◽  
Mammalian Retina ◽  
Show Evidence ◽  
Light Stimuli

We examined function of the feedback pathway from A17 GABAergic amacrine cells to rod bipolar cells (A17 feedback), a critically located inhibitory circuit in the classic rod pathway of the mammalian retina whose role in processing of scotopic visual information is still poorly understood. We show evidence that this A17 feedback has a profound influence on the temporal properties of rod-driven postphotoreceptoral responses (assessed with the scotopic electroretinogram b-wave). Application of a GABAcantagonist prolonged preferentially the decay of the scotopic b-wave. The degree of prolongation increased as the light intensity decreased. Application of selective GABAa antagonists accelerated the kinetics of the scotopic b-wave. This effect was abolished when the GABAc antagonist was coapplied. Selective ablation of A17 cells mimicked the action of the GABAc antagonist. In A17 cell–ablated retinas, the GABAc antagonist was no longer very effective to slow the decay of the scotopic b-wave. Thus the A17 feedback, activated by light stimulation and mediated mainly by the GABAc receptors, makes the scotopic b-wave more transient by accelerating preferentially its decay. The strength of the feedback can be modulated by GABAa receptor–mediated inhibition and by light intensity. Our results also suggest that in the mammalian retina the feedback may be a novel mechanism that contributes postphotoreceptorally to the termination of rod signals, especially those elicited by very dim light stimuli.

scholarly journals Activation of Neuronal Nicotinic Receptors Inhibits Acetylcholine Release in the Neuromuscular Junction by Increasing Ca2+ Flux through Cav1 Channels

2021 ◽  
Vol 22 (16) ◽  
pp. 9031
Author(s):  
Nikita Zhilyakov ◽  
Arsenii Arkhipov ◽  
Artem Malomouzh ◽  
Dmitry Samigullin
Keyword(s):  
Nervous System ◽  
Neuromuscular Junction ◽  
Calcium Influx ◽  
Motor Nerve ◽  
Calcium Transient ◽  
Receptor Activation ◽  
Motor Nerve Terminal ◽  
Ach Release ◽  
Neuronal Nicotinic Receptors ◽  
Presynaptic Calcium

Cholinergic neurotransmission is a key signal pathway in the peripheral nervous system and in several branches of the central nervous system. Despite the fact that it has been studied extensively for a long period of time, some aspects of its regulation still have not yet been established. One is the relationship between the nicotine-induced autoregulation of acetylcholine (ACh) release with changes in the concentration of presynaptic calcium levels. The mouse neuromuscular junction of m. Levator Auris Longus was chosen as the model of the cholinergic synapse. ACh release was assessed by electrophysiological methods. Changes in calcium transients were recorded using a calcium-sensitive dye. Nicotine hydrogen tartrate salt application (10 μM) decreased the amount of evoked ACh release, while the calcium transient increased in the motor nerve terminal. Both of these effects of nicotine were abolished by the neuronal ACh receptor antagonist dihydro-beta-erythroidine and Cav1 blockers, verapamil, and nitrendipine. These data allow us to suggest that neuronal nicotinic ACh receptor activation decreases the number of ACh quanta released by boosting calcium influx through Cav1 channels.

scholarly journals Living in the dark does not mean a blind life: bird and mammal visual communication in dim light

2017 ◽  
Vol 372 (1717) ◽  
pp. 20160064 ◽  
Author(s):  
Vincenzo Penteriani ◽  
María del Mar Delgado
Keyword(s):  
Visual Information ◽  
Visual Communication ◽  
Current Knowledge ◽  
Visual Signals ◽  
Visual Signal ◽  
Chemical Signalling ◽  
Coloration Pattern ◽  
Dim Light ◽  
Visual Signalling ◽  
Review Current

For many years, it was believed that bird and mammal communication ‘in the dark of the night’ relied exclusively on vocal and chemical signalling. However, in recent decades, several case studies have conveyed the idea that the nocturnal world is rich in visual information. Clearly, a visual signal needs a source of light to work, but diurnal light (twilight included, i.e. any light directly dependent on the sun) is not the only source of luminosity on this planet. Actually, moonlight represents a powerful source of illumination that cannot be neglected from the perspective of visual communication. White patches of feathers and fur on a dark background have the potential to be used to communicate with conspecifics and heterospecifics in dim light across different contexts and for a variety of reasons. Here: (i) we review current knowledge on visual signalling in crepuscular and nocturnal birds and mammals; and (ii) we also present some possible cases of birds and mammals that, due to the characteristics of their feather and fur coloration pattern, might use visual signals in dim light. Visual signalling in nocturnal animals is still an emerging field and, to date, it has received less attention than many other means of communication, including visual communication under daylight. For this reason, many questions remain unanswered and, sometimes, even unasked. This article is part of the themed issue ‘Vision in dim light’.

scholarly journals Activation of neuronal nicotinic receptors inhibits acetylcholine release in the neuromuscular junction by increasing Ca2+ flux through Cav1 channels

2021 ◽  
Author(s):  
Nikita Zhilyakov ◽  
Arsenii Arkhipov ◽  
Artem Malomouzh ◽  
Dmitry Samigullin
Keyword(s):  
Nervous System ◽  
Neuromuscular Junction ◽  
Calcium Influx ◽  
Motor Nerve ◽  
Calcium Transient ◽  
Motor Nerve Terminal ◽  
Stable Form ◽  
Ach Release ◽  
Presynaptic Calcium ◽  
Ach Receptors

Background and Purpose: Cholinergic neurotransmission is a key signal pathway in the peripheral nervous system (PNS) and in several branches of the central nervous system (CNS). Despite the fact that it has been studied extensively for a long period of time, some aspects of its regulation still have not yet been established. One is relationship between nicotine-induced autoregulation of acetylcholine (ACh) release with changes in the concentration of presynaptic calcium levels. Experimental Approach: The mouse neuromuscular junction of m. Levator Auris Longus was chosen as the model of the cholinergic synapse. ACh release was assessed by electrophysiological methods. Changes in the calcium transients were recorded using a calcium-sensitive dye. Functional interaction between nicotinic ACh receptors and calcium channels was investigated pharmacologically using specific agonists and antagonists. Key Results: Nicotine hydrogen tartrate salt (considered as a stable form for potential therapeutic delivery of nicotine) effects on the parameters of ACh release from the nerve ending were analyzed. Nicotine application (10 μM) decrease the amount of evoked ACh release, while calcium transient increase in the motor nerve terminal. Both of these effects of nicotine were abolished by the neuronal ACh receptor antagonist dihydro-beta-erythroidine and Cav1 blockers, verapamil and nitrendipine. Conclusion and Implications: Neuronal nicotinic ACh receptors activation decreases the number of ACh quanta released by boosting calcium influx through Cav1 channels. Understanding of mechanisms of autoregulation of ACh release is important for the searching new approaches treat diseases associated with cholinergic dysfunction.

Subcellular Localization and Complements of GABAA and GABAC Receptors on Bullfrog Retinal Bipolar Cells

2000 ◽  
Vol 84 (2) ◽  
pp. 666-676 ◽  
Author(s):  
Jiu-Lin Du ◽  
Xiong-Li Yang
Keyword(s):  
Subcellular Localization ◽  
Receptor Antagonist ◽  
Gaba Receptor ◽  
Drug Application ◽  
Bipolar Cells ◽  
Visual Signals ◽  
Receptor Subtypes ◽  
Inner Retina ◽  
Axon Terminals ◽  
Retinal Bipolar Cells

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.

Visual Anticipatory Information Modulates Multisensory Interactions of Artificial Audiovisual Stimuli

2010 ◽  
Vol 22 (7) ◽  
pp. 1583-1596 ◽  
Author(s):  
Jean Vroomen ◽  
Jeroen J. Stekelenburg
Keyword(s):  
Visual Information ◽  
Speech Sound ◽  
Human Action ◽  
Visual Signal ◽  
Multisensory Interactions ◽  
Temporal Occurrence ◽  
Audiovisual Stimuli ◽  
The Moment ◽  
Integrative Processing ◽  
Audiovisual Interaction

The neural activity of speech sound processing (the N1 component of the auditory ERP) can be suppressed if a speech sound is accompanied by concordant lip movements. Here we demonstrate that this audiovisual interaction is neither speech specific nor linked to humanlike actions but can be observed with artificial stimuli if their timing is made predictable. In Experiment 1, a pure tone synchronized with a deformation of a rectangle induced a smaller auditory N1 than auditory-only presentations if the temporal occurrence of this audiovisual event was made predictable by two moving disks that touched the rectangle. Local autoregressive average source estimation indicated that this audiovisual interaction may be related to integrative processing in auditory areas. When the moving disks did not precede the audiovisual stimulus—making the onset unpredictable—there was no N1 reduction. In Experiment 2, the predictability of the leading visual signal was manipulated by introducing a temporal asynchrony between the audiovisual event and the collision of moving disks. Audiovisual events occurred either at the moment, before (too “early”), or after (too “late”) the disks collided on the rectangle. When asynchronies varied from trial to trial—rendering the moving disks unreliable temporal predictors of the audiovisual event—the N1 reduction was abolished. These results demonstrate that the N1 suppression is induced by visual information that both precedes and reliably predicts audiovisual onset, without a necessary link to human action-related neural mechanisms.

Abstract P498: Polycystin-1 Regulates Excitation-contraction Coupling In Atrial Cardiomyocytes

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Troy Hendrickson ◽  
William Perez ◽  
Vincent Provasek ◽  
Francisco J Altamirano
Keyword(s):  
Electrical Stimulation ◽  
Action Potentials ◽  
Primary Cilia ◽  
Calcium Influx ◽  
Calcium Transient ◽  
Calcium Handling ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Atrial Cardiomyocytes ◽  
Atrial Excitation

Patients with Autosomal Dominant Polycystic Kidney disease (ADPKD) have multiple cardiovascular manifestations, including increased susceptibility to arrhythmias. Mutations in polycystin-1 (PC1) encoding gene accounts for 85% cases of ADPKD, whereas mutations in polycystin-2 (PC2) only accounts for 15%. In kidney cells, PC1 interacts with PC2 to form a protein complex at the primary cilia to regulate calcium influx via PC2. However, cardiomyocytes are non-ciliated cells and the role of both PC1 and PC2 in atrial cardiomyocytes remains unknown. We have previously demonstrated that PC1 regulates action potentials and calcium handling to fine-tune ventricular cardiomyocyte contraction. Here, we hypothesize that PC1 regulates action potentials and calcium handling in atrial cardiomyocytes independent of PC2 actions. To test this hypothesis, we differentiated human induced pluripotent stem cells (iPSC) into atrial cardiomyocytes (iPSC-aCM) using previously published protocols. To determine the contribution of PC1/PC2 in atrial excitation-contraction coupling, protein expression was knocked down utilizing specific siRNA constructs, for each protein, or a universal control siRNA transfected using lipofectamine RNAiMAX. We measured action potentials using the potentiometric dye FluoVolt and intracellular calcium with Fura-2 AM or Fluo-4. Changes in fluorescence were monitored using a multiwavelength IonOptix system. iPSC-aCM were paced at 2 Hz to synchronize the beating pattern using field electrical stimulation. Our data shows that PC1 ablation significantly decreased action potential duration at 50% and 80% of repolarization, by 24% and 23%, respectively. Moreover, we observed that PC1 knockdown significantly reduced calcium transient amplitude elicited by field electrical stimulation without changes in calcium transient decay. Interestingly, PC2 knockdown did not modify calcium transients in atrial cardiomyocytes (iPSC-aCM). Our data suggest that PC1 regulates atrial excitation-contraction coupling independent of PC2 actions. This study warrants further investigation into atrial dysfunction in ADPKD patients with PC1 mutations.

Sign in / Sign up

Export Citation Format

Share Document