scholarly journals Diurnal modulation of multivesicular release controls the efficiency of information transmission at a sensory synapse

2021 ◽  
Author(s):  
Jose Moya-Diaz ◽  
Ben James ◽  
Federico Esposti ◽  
Jamie Johnston ◽  
Leon Lagnado
Keyword(s):  
Information Transmission ◽  
Visual Processing ◽  
Internal State ◽  
Fold Increase ◽  
Bipolar Cells ◽  
Synaptic Function ◽  
Temporal Precision ◽  
Amount Of Information ◽  
Spontaneous Noise ◽  
Key Sites

Sensory circuits adapt to changes in the external world or the animal's internal state through the actions of neuromodulators. Synapses are key sites at which neuromodulators act but it is not known how they alter the amount of information transmitted. We investigated this question in the context of the diurnal regulation of visual processing in larval zebrafish, focusing on ribbon-type synapses of retinal bipolar cells. We demonstrate that contrast-sensitivity peaks in the afternoon accompanied by an average four-fold increase in the Shannon information transmitted at individual active zones. This increase reflects higher synaptic gain, lower spontaneous noise, reduced variability of stimulus-evoked release and improved temporal precision. Simultaneously, an increase in the probability of multivesicular events with larger information content increases the efficiency of information transmission (bits per vesicle) by factors of 2-3. The neuromodulator dopamine contributes to all these changes in synaptic function, although ON and OFF visual channels are differentially affected. Multivesicular release is a property of synapses in many parts of the brain and this study demonstrates that potentiation by neuromodulators can both increase the amount of information that is transmitted and the efficiency of transmission, revealing a previously unknown mechanism for adjusting neural processing.

Dynamical Constraints on Using Precise Spike Timing to Compute in Recurrent Cortical Networks

2008 ◽  
Vol 20 (4) ◽  
pp. 974-993 ◽  
Author(s):  
Arunava Banerjee ◽  
Peggy Seriès ◽  
Alexandre Pouget
Keyword(s):  
Dynamical System ◽  
Initial Conditions ◽  
Internal State ◽  
Spike Timing ◽  
Spiking Neurons ◽  
Spatiotemporal Patterns ◽  
Cortical Networks ◽  
Temporal Precision ◽  
Cortical Areas ◽  
Dynamical Constraints

Several recent models have proposed the use of precise timing of spikes for cortical computation. Such models rely on growing experimental evidence that neurons in the thalamus as well as many primary sensory cortical areas respond to stimuli with remarkable temporal precision. Models of computation based on spike timing, where the output of the network is a function not only of the input but also of an independently initializable internal state of the network, must, however, satisfy a critical constraint: the dynamics of the network should not be sensitive to initial conditions. We have previously developed an abstract dynamical system for networks of spiking neurons that has allowed us to identify the criterion for the stationary dynamics of a network to be sensitive to initial conditions. Guided by this criterion, we analyzed the dynamics of several recurrent cortical architectures, including one from the orientation selectivity literature. Based on the results, we conclude that under conditions of sustained, Poisson-like, weakly correlated, low to moderate levels of internal activity as found in the cortex, it is unlikely that recurrent cortical networks can robustly generate precise spike trajectories, that is, spatiotemporal patterns of spikes precise to the millisecond timescale.

A role for 5HT3 receptors in visual processing in the mammalian retina

1993 ◽  
Vol 10 (3) ◽  
pp. 511-522 ◽  
Author(s):  
William J. Brunken ◽  
Xiao-Tao Jin
Keyword(s):  
Visual Processing ◽  
Ganglion Cells ◽  
Cell Activity ◽  
Phosphatidyl Inositol ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Reciprocal Effect ◽  
Mammalian Retina ◽  
Messenger System

AbstractWe investigated the role of 5HT3 receptors in the mammalian retina using electrophysiological techniques to monitor ganglion cell activity. Activation of 5HT3 receptors with the selective agonist 1-phenylbiguanide (PBG) increased the ON responses of ON-center ganglion cells, while decreasing the OFF responses of OFF-center cells. The application of a selective 5HT3 antagonist had a reciprocal effect, namely it reduced the center response in ON-center cells and concomitantly increased the center responses in OFF-center cells. Since putative serotoninergic amacrine cells in the retina are connected specifically to the rod bipolar cell, these agents most likely affect the rod bipolar terminal. These data, together with previous studies, suggest that both 5HT2 and 5HT3 receptors mediate an excitatory influence which serves to facilitate the output from rod bipolar cells, the former via a phosphatidyl inositol second-messenger system, and the latter via a direction channel.

Information Transmission in Normal and Schizophrenic Subjects by Grids and Tilt of Matrix Patterns

1980 ◽  
Vol 47 (2) ◽  
pp. 552-554 ◽  
Author(s):  
Prem Shanker
Keyword(s):  
Information Transmission ◽  
Normal Subjects ◽  
Factorial Experiment ◽  
Amount Of Information ◽  
Schizophrenic Patients

To measure the amount of information transmitted by matrices containing dots in various patterns, a 2 × 3 × 2 (subjects × matrices × tilt) randomized groups design with factorial experiment was used. 60 normal subjects and 60 hospitalized schizophrenic patients were tested with 27 matrices in two angular positions. The normal subjects received more information from the stimuli than the schizophrenics. The matrices with horizontal grids transmitted more information than those with no grids or oblique grids. The stimuli without any tilt transmitted more information than the ones with a 45° counterclockwise tilt.

scholarly journals State-dependent control of cortical processing speed via gain modulation

2020 ◽  
Author(s):  
David Wyrick ◽  
Luca Mazzucato
Keyword(s):  
Information Processing ◽  
Processing Speed ◽  
Visual Processing ◽  
Large Scale ◽  
Internal State ◽  
Gain Modulation ◽  
Cell Type ◽  
Information Processing Speed ◽  
Afferent Projections ◽  
Cell Type Specific

AbstractTo thrive in dynamic environments, animals can generate flexible behavior and rapidly adapt responses to a changing context and internal state. Examples of behavioral flexibility include faster stimulus responses when attentive and slower responses when distracted. Contextual modulations may occur early in the cortical hierarchy and may be implemented via afferent projections from top-down pathways or neuromodulation onto sensory cortex. However, the computational mechanisms mediating the effects of such projections are not known. Here, we investigate the effects of afferent projections on the information processing speed of cortical circuits. Using a biologically plausible model based on recurrent networks of excitatory and inhibitory neurons arranged in cluster, we classify the effects of cell-type specific perturbations on the circuit’s stimulus-processing capability. We found that perturbations differentially controlled processing speed, leading to counter-intuitive effects such as improved performance with increased input variance. Our theory explains the effects of all perturbations in terms of gain modulation, which controls the timescale of the circuit dynamics. We tested our model using large-scale electrophysiological recordings from the visual hierarchy in freely running mice, where a decrease in single-cell gain during locomotion explained the observed acceleration of visual processing speed. Our results establish a novel theory of cell-type specific perturbations linking connectivity, dynamics, and information processing via gain modulations.

scholarly journals Fructose 1,6-bisphosphatase: getting the message across

2019 ◽  
Vol 39 (3) ◽  
Author(s):  
David J. Timson
Keyword(s):  
Information Transmission ◽  
Binding Site ◽  
Metal Ion ◽  
Drug Target ◽  
Fold Increase ◽  
Fructose 1,6 Bisphosphatase ◽  
Additional Detail ◽  
Key Enzyme ◽  
Mammalian Enzyme ◽  
The Warburg Effect

Abstract Fructose 1,6-bisphosphatase (FBPase) is a key enzyme in gluconeogenesis. It is a potential drug target in the treatment of type II diabetes. The protein is also associated with a rare inherited metabolic disease and some cancer cells lack FBPase activity which promotes glycolysis facilitating the Warburg effect. Thus, there is interest in both inhibiting the enzyme (for diabetes treatment) and restoring its activity (in relevant cancers). The mammalian enzyme is tetrameric, competitively inhibited by Fructose 2,6-bisphosphate and negatively allosterically regulated by AMP. This allosteric regulation requires information transmission between the AMP binding site and the active site of the enzyme. A recent paper by Topaz et al. (Bioscience Reports (2019) 39, pii:BSR20180960) has added additional detail to our understanding of this information transmission process. Two residues in the AMP binding site (Lys112 and Tyr113) were shown to be involved in initiating the message between the two sites. This tyrosine residue has recently be shown to be important with protein’s interaction with the antidiabetic drug metformin. A variant designed to increase metal ion affinity (M248D) resulted in a five-fold increase in enzymatic activity. Interestingly alterations of two residues at the subunit interfaces (Tyr164 and Met177) resulted in increased responsiveness to AMP. Overall, these findings may have implications in the design of novel FBPase inhibitors or activators.

The influences of metabotropic receptor activation on cellular signaling and synaptic function in amacrine cells

2011 ◽  
Vol 29 (1) ◽  
pp. 31-39 ◽  
Author(s):  
EVANNA GLEASON
Keyword(s):  
Metabotropic Glutamate Receptors ◽  
Cannabinoid Receptors ◽  
Cell Function ◽  
Amacrine Cells ◽  
Receptor Activation ◽  
Bipolar Cells ◽  
Synaptic Function ◽  
Metabotropic Receptors ◽  
Metabotropic Receptor ◽  
Metabotropic Glutamate

AbstractAmacrine cells receive glutamatergic input from bipolar cells and GABAergic, glycinergic, cholinergic, and dopaminergic input from other amacrine cells. Glutamate, GABA, glycine, and acetylcholine (ACh) interact with ionotropic receptors and it is these interactions that form much of the functional circuitry in the inner retina. However, glutamate, GABA, ACh, and dopamine also activate metabotropic receptors linked to second messenger pathways that have the potential to modify the function of individual cells as well as retinal circuitry. Here, the physiological effects of activating dopamine receptors, metabotropic glutamate receptors, GABAB receptors, and muscarinic ACh receptors on amacrine cells will be discussed. The retina also expresses metabotropic receptors and the biochemical machinery associated with the synthesis and degradation of endocannabinoids and sphingosine-1-phosphate (S1P). The effects of activating cannabinoid receptors and S1P receptors on amacrine cell function will also be addressed.

ACTIVE NETWORKS THAT MAXIMIZE THE AMOUNT OF INFORMATION TRANSMISSION

2012 ◽  
Vol 22 (02) ◽  
pp. 1230008 ◽  
Author(s):  
M. S. BAPTISTA ◽  
J. X. DE CARVALHO ◽  
M. S. HUSSEIN ◽  
C. GREBOGI
Keyword(s):  
Neural Networks ◽  
Information Transmission ◽  
Network Topology ◽  
Laplacian Matrix ◽  
Active Networks ◽  
Amount Of Information ◽  
Theoretical Approaches ◽  
The Matrix ◽  
And Behavior ◽  
The Relationship

This work clarifies the relationship between network circuit (topology) and behavior (information transmission and synchronization) in active networks, e.g. neural networks. As an application, we show how to determine a network topology that is optimal for information transmission. By optimal, we mean that the network is able to transmit a large amount of information, it possesses a large number of communication channels, and it is robust under large variations of the network coupling configuration. This theoretical approach is general and does not depend on the particular dynamic of the elements forming the network, since the network topology can be determined by finding a Laplacian matrix (the matrix that describes the connections and the coupling strengths among the elements) whose eigenvalues satisfy some special conditions. To illustrate our ideas and theoretical approaches, we use neural networks of electrically connected chaotic Hindmarsh–Rose neurons.

Morphological differentiation of bipolar cells in the ferret retina

1999 ◽  
Vol 16 (6) ◽  
pp. 1133-1144 ◽  
Author(s):  
E.D. MILLER ◽  
M.N. TRAN ◽  
G.-K. WONG ◽  
D.M. OAKLEY ◽  
R.O.L. WONG
Keyword(s):  
Visual Processing ◽  
Plexiform Layer ◽  
Morphological Differentiation ◽  
Bipolar Cells ◽  
Inner Plexiform Layer ◽  
Axon Terminals ◽  
Ribbon Synapses ◽  
Rod Bipolar Cells ◽  
Cone Bipolar Cells ◽  
Dye Labeling

Bipolar cells are not only important for visual processing but input from these cells may underlie the reorganization of ganglion cell dendrites in the inner plexiform layer (IPL) during development. Because little is known about the development of bipolar cells, here we have used immunocytochemical markers and dye labeling to identify and follow their differentiation in the neonatal ferret retina. Putative cone bipolar cells were immunoreacted for calbindin and recoverin, and rod bipolar cells were immunostained for protein kinase C (PKC). Our results show that calbindin-immunoreactive cone bipolar cells appear at postnatal day 15 (P15), at which time their axonal terminals are already localized to the inner half of the IPL. By contrast, recoverin-immunoreactive cells with terminals in the IPL are present at birth, but many of these cells may be immature photoreceptors. By the second postnatal week, recoverin-positive cells resembling cone bipolar cells were clearly present, and with increasing age, two distinct strata of immunolabeled processes occupied the IPL. PKC-containing rod bipolar cells emerged by the fourth postnatal week and at this age have stratified arbors in the inner IPL. The early bias of bipolar axonal arbors in terminating in the inner or outer half of the IPL is confirmed by dye labeling of cells with somata in the inner nuclear layer. At P10, several days before ribbon synapses have been previously observed in the ferret IPL, the axon terminals of all dye-labeled bipolar cells were clearly stratified. The results suggest that bipolar cells could provide spatially localized interactions that are suitable for guiding dendritic lamination in the inner retina.

scholarly journals Asymmetric Distributions of Achromatic Bipolar Cells in the Mouse Retina

2022 ◽  
Vol 15 ◽  
Author(s):  
Zachary J. Sharpe ◽  
Angela Shehu ◽  
Tomomi Ichinose
Keyword(s):  
Visual Processing ◽  
Fluorescent Protein ◽  
Bipolar Cells ◽  
Mouse Retina ◽  
Temporal Region ◽  
Retinal Tissue ◽  
Evolutionary Changes ◽  
Asymmetric Distributions ◽  
Nasal Region ◽  
Green Fluorescent

In the retina, evolutionary changes can be traced in the topography of photoreceptors. The shape of the visual streak depends on the height of the animal and its habitat, namely, woods, prairies, or mountains. Also, the distribution of distinct wavelength-sensitive cones is unique to each animal. For example, UV and green cones reside in the ventral and dorsal regions in the mouse retina, respectively, whereas in the rat retina these cones are homogeneously distributed. In contrast with the abundant investigation on the distribution of photoreceptors and the third-order neurons, the distribution of bipolar cells has not been well understood. We utilized two enhanced green fluorescent protein (EGFP) mouse lines, Lhx4-EGFP (Lhx4) and 6030405A18Rik-EGFP (Rik), to examine the topographic distributions of bipolar cells in the retina. First, we characterized their GFP-expressing cells using type-specific markers. We found that GFP was expressed by type 2, type 3a, and type 6 bipolar cells in the Rik mice and by type 3b, type 4, and type 5 bipolar cells in the Lhx4 mice. All these types are achromatic. Then, we examined the distributions of bipolar cells in the four cardinal directions and three different eccentricities of the retinal tissue. In the Rik mice, GFP-expressing bipolar cells were more highly observed in the nasal region than those in the temporal retina. The number of GFP cells was not different along with the ventral-dorsal axis. In contrast, in the Lhx4 mice, GFP-expressing cells occurred at a higher density in the ventral region than in the dorsal retina. However, no difference was observed along the nasal-temporal axis. Furthermore, we examined which type of bipolar cells contributed to the asymmetric distributions in the Rik mice. We found that type 3a bipolar cells occurred at a higher density in the temporal region, whereas type 6 bipolar cells were denser in the nasal region. The asymmetricity of these bipolar cells shaped the uneven distribution of the GFP cells in the Rik mice. In conclusion, we found that a subset of achromatic bipolar cells is asymmetrically distributed in the mouse retina, suggesting their unique roles in achromatic visual processing.

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.

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