scholarly journals Neural mechanism of experience-dependent sensory gain control in C. elegans

2021 ◽  
Author(s):  
Yosuke Ikejiri ◽  
Yuki Tanimoto ◽  
Kosuke Fujita ◽  
Fumie Hiramatsu ◽  
Shuhei J. Yamazaki ◽  
...  
Keyword(s):  
Gradual Increase ◽  
Adaptive Modulation ◽  
Gain Control ◽  
Neural Mechanism ◽  
Fast Component ◽  
Protein Signaling ◽  
Nociceptive Neurons ◽  
C Elegans ◽  
Stimulus Response ◽  
Integrative Study

Animals' sensory systems adjust their responsiveness to environmental stimuli that vary greatly in their intensity. Here we report the neural mechanism of experience-dependent sensory adjustment, especially gain control, in the ASH nociceptive neurons in Caenorhabditis elegans. Using calcium imaging under gradual changes in stimulus intensity, we find that the ASH neurons of naive animals respond to concentration increases in a repulsive odor 2-nonanone regardless of the magnitude of the concentration increase. However, after preexposure to the odor, the ASH neurons exhibit significantly weak responses to a small gradual increase in odor concentration while their responses to a large gradual increase remain strong. Thus, preexposure changes the slope of stimulus-response relationships (i.e., gain control). Behavioral analysis suggests that this gain control contributes to the preexposure-dependent enhancement of odor avoidance behavior. Mathematical analysis reveals that the ASH response consists of fast and slow components, and that the fast component is specifically suppressed by preexposure. In addition, genetic analysis suggests that G protein signaling is required for the fast component. Thus, our integrative study demonstrates how prior experience dynamically modulates stimulus-response relationships in sensory neurons, eventually leading to adaptive modulation of behavior.

scholarly journals Hierarchical decision processes that operate over distinct timescales underlie choice and changes in strategy

2016 ◽  
Vol 113 (31) ◽  
pp. E4531-E4540 ◽  
Author(s):  
Braden A. Purcell ◽  
Roozbeh Kiani
Keyword(s):  
Decision Making ◽  
Neural Mechanism ◽  
Decision Processes ◽  
Response Strategy ◽  
Limited Information ◽  
Decision Strategy ◽  
Stimulus Response ◽  
Hierarchical Decision ◽  
The Right ◽  
High Level

Decision-making in a natural environment depends on a hierarchy of interacting decision processes. A high-level strategy guides ongoing choices, and the outcomes of those choices determine whether or not the strategy should change. When the right decision strategy is uncertain, as in most natural settings, feedback becomes ambiguous because negative outcomes may be due to limited information or bad strategy. Disambiguating the cause of feedback requires active inference and is key to updating the strategy. We hypothesize that the expected accuracy of a choice plays a crucial rule in this inference, and setting the strategy depends on integration of outcome and expectations across choices. We test this hypothesis with a task in which subjects report the net direction of random dot kinematograms with varying difficulty while the correct stimulus−response association undergoes invisible and unpredictable switches every few trials. We show that subjects treat negative feedback as evidence for a switch but weigh it with their expected accuracy. Subjects accumulate switch evidence (in units of log-likelihood ratio) across trials and update their response strategy when accumulated evidence reaches a bound. A computational framework based on these principles quantitatively explains all aspects of the behavior, providing a plausible neural mechanism for the implementation of hierarchical multiscale decision processes. We suggest that a similar neural computation—bounded accumulation of evidence—underlies both the choice and switches in the strategy that govern the choice, and that expected accuracy of a choice represents a key link between the levels of the decision-making hierarchy.

P2X Receptor–Mediated Ionic Currents in Dorsal Root Ganglion Neurons

1999 ◽  
Vol 82 (3) ◽  
pp. 1590-1598 ◽  
Author(s):  
Edward C. Burgard ◽  
Wende Niforatos ◽  
Tim van Biesen ◽  
Kevin J. Lynch ◽  
Edward Touma ◽  
...  
Keyword(s):  
Dorsal Root ◽  
Slow Component ◽  
Ionic Currents ◽  
P2x Receptors ◽  
Fast Component ◽  
Dorsal Root Ganglion Neurons ◽  
P2x Receptor ◽  
Receptor Subtype ◽  
Nociceptive Neurons ◽  
Ganglion Neurons

Nociceptive neurons in the dorsal root ganglia (DRG) are activated by extracellular ATP, implicating P2X receptors as potential mediators of painful stimuli. However, the P2X receptor subtype(s) underlying this activity remain in question. Using electrophysiological techniques, the effects of P2X receptor agonists and antagonists were examined on acutely dissociated adult rat lumbar DRG neurons. Putative P2X-expressing nociceptors were identified by labeling neurons with the lectin IB4. These neurons could be grouped into three categories based on response kinetics to extracellularly applied ATP. Some DRG responses (slow DRG) were relatively slowly activating, nondesensitizing, and activated by the ATP analogue α,β-meATP. These responses resembled those recorded from 1321N1 cells expressing recombinant heteromultimeric rat P2X2/3 receptors. Other responses (fast DRG) were rapidly activating and desensitized almost completely during agonist application. These responses had properties similar to those recorded from 1321N1 cells expressing recombinant rat P2X3 receptors. A third group (mixed DRG) activated and desensitized rapidly (P2X3-like), but also had a slow, nondesensitizing component that functionally prolonged the current. Like the fast component, the slow component was activated by both ATP and α,β-meATP and was blocked by the P2X antagonist TNP-ATP. But unlike the fast component, the slow component could follow high-frequency activation by agonist, and its amplitude was potentiated under acidic conditions. These characteristics most closely resemble those of rat P2X2/3 receptors. These data suggest that there are at least two populations of P2X receptors present on adult DRG nociceptive neurons, P2X3 and P2X2/3. These receptors are expressed either separately or together on individual neurons and may play a role in the processing of nociceptive information from the periphery to the spinal cord.

scholarly journals Heterotrimeric G protein signaling functions with dynein to promote spindle positioning in C. elegans

2007 ◽  
Vol 179 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Claudia Couwenbergs ◽  
Jean-Claude Labbé ◽  
Morgan Goulding ◽  
Thomas Marty ◽  
Bruce Bowerman ◽  
...  
Keyword(s):  
G Protein ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
Dynein Light Chain ◽  
Loss Of Function ◽  
Functional Link ◽  
Heterotrimeric G Protein ◽  
Spindle Positioning ◽  
C Elegans ◽  
Heterotrimeric G Protein Signaling

Proper orientation and positioning of the mitotic spindle is essential for the correct segregation of fate determinants during asymmetric cell division. Although heterotrimeric G proteins and their regulators are essential for spindle positioning in many cell types, their mechanism of action remains unclear. In this study, we show that dyrb-1, which encodes a dynein light chain, provides a functional link between heterotrimeric G protein signaling and dynein activity during spindle positioning in Caenorhabditis elegans. Embryos depleted of dyrb-1 display phenotypes similar to a weak loss of function of dynein activity, indicating that DYRB-1 is a positive regulator of dynein. We find that the depletion of dyrb-1 enhances the spindle positioning defect of weak loss of function alleles of two regulators of G protein signaling, LIN-5 and GPR-1/2, and that DYRB-1 physically associates with these two proteins. These results indicate that dynein activity functions with regulators of G protein signaling to regulate common downstream effectors during spindle positioning in the early C. elegans embryo.

scholarly journals Tuning Low-Voltage-Activated A-Current for Silent Gain Modulation

2012 ◽  
Vol 24 (12) ◽  
pp. 3181-3190 ◽  
Author(s):  
Ameera X. Patel ◽  
Naomi Murphy ◽  
Denis Burdakov
Keyword(s):  
Low Voltage ◽  
Model Neuron ◽  
Low Frequency ◽  
Gain Control ◽  
Inactivation Kinetics ◽  
Stimulus Response ◽  
Functional Capabilities ◽  
Low Threshold ◽  
Intrinsic Firing ◽  
Current Mechanism

Modulation of stimulus-response gain and stability of spontaneous (unstimulated) firing are both important for neural computation. However, biologically plausible mechanisms that allow these distinct functional capabilities to coexist in the same neuron are poorly defined. Low-threshold, inactivating (A-type) K+ currents (IA) are found in many biological neurons and are historically known for enabling low-frequency firing. By performing simulations using a conductance-based model neuron, here we show that biologically plausible shifts in IA conductance and inactivation kinetics produce dissociated effects on gain and intrinsic firing. This enables IA to regulate gain without major changes in intrinsic firing rate. Tuning IA properties may thus represent a previously unsuspected single-current mechanism of silent gain control in neurons.

scholarly journals An extrasynaptic GABAergic signal modulates a pattern of forward movement in Caenorhabditis elegans

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Yu Shen ◽  
Quan Wen ◽  
He Liu ◽  
Connie Zhong ◽  
Yuqi Qin ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Activity Patterns ◽  
Gain Control ◽  
Metabotropic Receptors ◽  
Forward Movement ◽  
C Elegans ◽  
A Value ◽  
Signaling Mechanisms ◽  
Optimal Efficiency ◽  
Gabaergic Modulation

As a common neurotransmitter in the nervous system, γ-aminobutyric acid (GABA) modulates locomotory patterns in both vertebrates and invertebrates. However, the signaling mechanisms underlying the behavioral effects of GABAergic modulation are not completely understood. Here, we demonstrate that a GABAergic signal in C. elegans modulates the amplitude of undulatory head bending through extrasynaptic neurotransmission and conserved metabotropic receptors. We show that the GABAergic RME head motor neurons generate undulatory activity patterns that correlate with head bending and the activity of RME causally links with head bending amplitude. The undulatory activity of RME is regulated by a pair of cholinergic head motor neurons SMD, which facilitate head bending, and inhibits SMD to limit head bending. The extrasynaptic neurotransmission between SMD and RME provides a gain control system to set head bending amplitude to a value correlated with optimal efficiency of forward movement.

Response Properties and Organization of Nociceptive Neurons in Area 1 of Monkey Primary Somatosensory Cortex

2000 ◽  
Vol 84 (2) ◽  
pp. 719-729 ◽  
Author(s):  
Dan R. Kenshalo ◽  
Koichi Iwata ◽  
Maurice Sholas ◽  
David A. Thomas
Keyword(s):  
Somatosensory Cortex ◽  
Dynamic Range ◽  
Receptive Fields ◽  
Primary Somatosensory Cortex ◽  
Isolated Cells ◽  
Nociceptive Neurons ◽  
Response Properties ◽  
Stimulus Response ◽  
Noxious Mechanical Stimulation ◽  
Wdr Neurons

The organization and response properties of nociceptive neurons in area 1 of the primary somatosensory cortex (SI) of anesthetized monkeys were examined. The receptive fields of nociceptive neurons were classified as either wide-dynamic-range (WDR) neurons that were preferentially responsive to noxious mechanical stimulation, or nociceptive specific (NS) that were responsive to only noxious stimuli. The cortical locations and the responses of the two classes of neurons were compared. An examination of the neuronal stimulus-response functions obtained during noxious thermal stimulation of the glabrous skin of the foot or the hand indicated that WDR neurons exhibited significantly greater sensitivity to noxious thermal stimuli than did NS neurons. The receptive fields of WDR neurons were significantly larger than the receptive fields of NS neurons. Nociceptive SI neurons were somatotopically organized. Nociceptive neurons with receptive fields on the foot were located more medial in area 1 of SI than those with receptive fields on the hand. In the foot representation, the recording sites of nociceptive neurons were near the boundary between areas 3b and 1, whereas in the hand area, there was a tendency for them to be located more caudal in area 1. The majority of nociceptive neurons were located in the middle layers (III and IV) of area 1. The fact that nociceptive neurons were not evenly distributed across the layers of area 1 suggested that columns of nociceptive neurons probably do not exist in the somatosensory cortex. In electrode tracks where nociceptive neurons were found, approximately half of all subsequently isolated neurons were also classified as nociceptive. Low-threshold mechanoreceptive (LTM) neurons were intermingled with nociceptive neurons. Both WDR and NS neurons were found in close proximity to one another. In instances where the receptive field shifted, subsequently isolated cells were also classified as nociceptive. These data suggest that nociceptive neurons in area 1 of SI are organized in vertically orientated aggregations or clusters in layers III and IV.

scholarly journals Repeated whisker stimulation evokes invariant neuronal responses in the dorsolateral striatum of anesthetized rats: a potential correlate of sensorimotor habits

2011 ◽  
Vol 105 (5) ◽  
pp. 2225-2238 ◽  
Author(s):  
Todd M. Mowery ◽  
Jon B. Harrold ◽  
Kevin D. Alloway
Keyword(s):  
Barrel Cortex ◽  
Neural Mechanism ◽  
Brain Regions ◽  
Original Position ◽  
Induced Response ◽  
Neuronal Responses ◽  
Dorsolateral Striatum ◽  
Stimulus Response ◽  
Computer Controlled ◽  
Whisker Stimulation

The dorsolateral striatum (DLS) receives extensive projections from primary somatosensory cortex (SI), but very few studies have used somesthetic stimulation to characterize the sensory coding properties of DLS neurons. In this study, we used computer-controlled whisker deflections to characterize the extracellular responses of DLS neurons in rats lightly anesthetized with isoflurane. When multiple whiskers were synchronously deflected by rapid back-and-forth movements, whisker-sensitive neurons in the DLS responded to both directions of movement. The latency and magnitude of these neuronal responses displayed very little variation with changes in the rate (2, 5, or 8 Hz) of whisker stimulation. Simultaneous recordings in SI barrel cortex and the DLS revealed important distinctions in the neuronal responses of these serially connected brain regions. In contrast to DLS neurons, SI neurons were activated by the initial deflection of the whiskers but did not respond when the whiskers moved back to their original position. As the rate of whisker stimulation increased, SI responsiveness declined, and the latencies of the responses increased. In fact, when whiskers were deflected at 5 or 8 Hz, many neurons in the DLS responded before the SI neurons. These results and earlier anatomic findings suggest that a component of the sensory-induced response in the DLS is mediated by inputs from the thalamus. Furthermore, the lack of sensory adaptation in the DLS may represent a critical part of the neural mechanism by which the DLS encodes stimulus-response associations that trigger motor habits and other stimulus-evoked behaviors that are not contingent on rewarded outcomes.

scholarly journals Bounded Rationality in C. elegans

2018 ◽  
Author(s):  
Dror Cohen ◽  
Meshi Volovich ◽  
Yoav Zeevi ◽  
Lilach Elbaum ◽  
Kenway Louie ◽  
...  
Keyword(s):  
Bounded Rationality ◽  
Rational Choice Theory ◽  
Choice Theory ◽  
Gain Control ◽  
Information Coding ◽  
Genetic Manipulations ◽  
C Elegans ◽  
Choice Sets ◽  
Basic Axiom ◽  
Value Coding

AbstractRational choice theory assumes optimality in decision-making. Violations of a basic axiom of economic rationality known as “Independence of Irrelevant Alternatives” (IIA), have been demonstrated in both humans and animals, and could stem from common neuronal constraints. We developed tests for IIA in the nematode Caenorhabditis elegans, an animal with only 302 neurons, using olfactory chemotaxis assays. We found that in most cases C. elegans make rational decisions. However, by probing multiple neuronal architectures using various choice sets, we show that asymmetric sensation of odor options by the AWCON neuron can lead to violations of rationality. We further show that genetic manipulations of the asymmetry between the AWC neurons can make the worm rational or irrational. Last, a normalization-based model of value coding and gain control explains how particular neuronal constraints on information coding give rise to irrationality. Thus, we demonstrate that bounded rationality could arise due to basic neuronal constraints.

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