scholarly journals The Telson Flexor Neuromuscular System of the Crayfish: III. The Role of Feedforward Inhibition in Shaping a Stereotyped Behaviour Pattern

1987 ◽  
Vol 127 (1) ◽  
pp. 295-311
Author(s):  
J. P. C. DUMONT ◽  
J. J. WINE
Keyword(s):  
Sensory Input ◽  
Giant Axon ◽  
Behaviour Pattern ◽  
Flexor Muscles ◽  
Motor Neurones ◽  
Observed Behaviour ◽  
Direct Input ◽  
Stimulation Of ◽  
Feedforward Inhibition

1. The telson flexor system is homologous to the fast flexor system of anterior ganglia (Dumont & Wine, 1986a), but important differences exist in connections to the telson motor giants (MoGs) (Dumont & Wine, 1986b). In this paper, we describe additional differences in connections to the telson non-giant fast flexor (FF) motor neurones and to the telson flexor inhibitor (FI). 2. The telson FF motor neurones in ganglion 6 (G6) receive inputs similar to those in G4 and G5 (Miller, Hagiwara & Wine, 1985). The escape command neurones (lateral giants, LGs, and medial giants, MGs) in common provide weak disynaptic input via the telson segmental giant (SG6), and relatively strong trisynaptic input via SG2, SG3 and the corollary discharge interneurones 12 and 13. There may also be some direct input from the MGs, but it, as well as the connections from SG6, appears to vary in different preparations. 3. The compound PSP produced in telson FFs by a single LG or MG impulse was suprathreshold in only five of 55 experiments in isolated abdominal nerve cords, but the probability that a motor neurone would fire increased with additional giant axon impulses, showing that temporal summation of excitation outweighed the possible recruitment of inhibition. Firing probability was higher in semi-intact preparations, where at least one posterior telson FF was fired by a single LG impulse 50% of the time. As was pointed out previously (Dumont & Wine, 1986b), telson flexion would disrupt the behaviour pattern expected from LG commands. 4. Two pathways of feedforward inhibition were found which prevent such disruption. The sensory input that recruits the LG also recruits powerful feedforward inhibition of the telson FF motor neurones, which reduces the probability that they will be fired by the LG. The same sensory stimulus also evokes inhibition of FFs in G5, excitation of FFs in G2 and G3, and mixed excitation and inhibition of FFs in G4. In addition, the telson FIs fire at short latency during LG-mediated tailflips. This occurs because the telson FIs are excited by sensory input. In fact, the firing threshold of the telson FIs to sensory input is lower than that of the LGs, at least for electrical stimulation of nerves. When the LGs do fire, they produce additional excitation of the FIs. The telson FIs also are excited by the LGs but not by the MGs. In contrast, the anterior homologues of the telson FIs receive equivalent, delayed excitation from both MGs and LGs, and weaker sensory input, so that they tend to fire only after the peak of flexion (Wine & Mistick, 1977). 5. The predicted net effect of these connections is that the telson flexor muscles should not contract during naturally elicited LG tailflips, and this is consistent with observed behaviour. The results can be interpreted as providing additional examples of potentially maladaptive central connections which are not expressed in behaviour because of feedforward inhibition.

Neuromuscular transmission in the jellyfish Aglantha digitale

1985 ◽  
Vol 116 (1) ◽  
pp. 1-25 ◽  
Author(s):  
P. A. Kerfoot ◽  
G. O. Mackie ◽  
R. W. Meech ◽  
A. Roberts ◽  
C. L. Singla
Keyword(s):  
Dimensional Space ◽  
Thin Sheet ◽  
Current Source ◽  
Giant Axon ◽  
The Body ◽  
Two Dimensional ◽  
Bathing Medium ◽  
Giant Axons ◽  
Motor Neurones ◽  
Stimulation Of

In the jellyfish Aglantha digitale escape swimming is mediated by the nearly synchronous activity of eight giant motor axons which make direct synaptic contact with contractile myoepithelial cells on the under-surface of the body wall. The delay in transmission at these synapses was 0.7 +/− 0.1 ms (+/− S.D.;N = 6) at 12 degrees C as measured from intracellular records. Transmission depended on the presence of Ca2+ in the bathing medium. It was not blocked by increasing the level of Mg2+ to 127 mmol l-1. The myoepithelium is a thin sheet of electrically coupled cells and injection of current at one point was found to depolarize the surrounding cells. The potential change declined with distance from the current source as expected for two-dimensional current spread. The two-dimensional space constant (lambda) was 770 micron for current flow in the circular direction and 177 micron for radial flow. The internal resistance of the epithelium (178–201 omega cm) and the membrane time constant (5–10 ms) were direction independent. No propagated epithelial action potentials were observed. Spontaneous miniature synaptic potentials of similar amplitude and rise-time were recorded intracellularly at distances of up to 1 mm from the motor giant axon. Ultrastructural evidence confirms that neuro-myoepithelial synapses also occur away from the giant axons. It is likely that synaptic sites are widespread in the myoepithelium, probably associated with the lateral motor neurones as well as the giant axons. Local stimulation of lateral motor neurones generally produced contraction in distinct fields. We suppose that stimulation of a single motor giant axon excites a whole population of lateral motor neurones and hence a broad area of the myoepithelium.

GRAVITY DEPENDENT MECHANISMS OF SENSORIMOTOR REGULATION OFPOSTUREANDLOCOMOTION

2020 ◽  
Vol 54 (6) ◽  
pp. 27-42
Author(s):  
Yu. Gerasimenko ◽  
◽  
V.R. Edgerton ◽  
S. Harkema ◽  
I. Kozlovskaya ◽  
...  
Keyword(s):  
Functional State ◽  
Sensory Input ◽  
Motor Tasks ◽  
Muscle System ◽  
Support Afferentation ◽  
Leading Role ◽  
Injured Brain ◽  
Postural Synergies ◽  
Stimulation Of

This review is dedicated to the memory of Inesa Kozlovskaya, whose contributions to gravitational physiology was and will continue to be decisive. Dr. Kozlovskaya has developed the concept of gravity-dependent motor control and substantiated the role of supporting afferentation in postural – tonic regulation. It was shown that the support afferentation plays the leading role in the control of the tonic muscle system and regulation of postural synergies. In this review the modern mechanisms of posture-locomotion integration as well as the mechanisms of sensory-motor regulation based on stimulation of foot and muscle receptors in combination with spinal cord stimulation will be considered. Based on the results presented in this review the concept of neurorehabilitation is proposed to be considered as the implementation of various neuromodulations aimed at regulating the functional state of the injured nervous system. The concept is based on the interaction of the processes of regulation of the functional state of the injured brain and sensory input during executing of motor tasks.

The Nervous Control of Limb Autotomy in the Hermit Crab Pagurus Bernhardus (L.) and the Role of the Cuticular Stress Detector, CSD1

1977 ◽  
Vol 70 (1) ◽  
pp. 93-104 ◽  
Author(s):  
IAN FINDLAY ◽  
ALISTAIR MCVEAN
Keyword(s):  
Hermit Crab ◽  
Sensory Information ◽  
Sense Organ ◽  
Nervous Control ◽  
Limb Segment ◽  
Motor Neurones ◽  
Pagurus Bernhardus ◽  
Stimulation Of

Limb autotomy results from the fracture of a preformed breakage plane within the second limb segment. Fracture is produced by the contraction of the large anterior levator (AL) muscle at the same time as its synergist, the posterior levator (PL) muscle. The AL force is thus directed on to a small portion of the breakage plane; withdrawal of this plug initiates cuticular fracture. Autotomy is a response to damage inflicted on the limb. In the absence of sensory information from the second limb segment there is less activity in the units serving the PL. It is shown that stimulation of the sense organ, cuticular stress detector one, provides feedback to PL motor neurones. The feedback is an integral part of the nervous control of limb autotomy.

Crayfish Escape Behaviour: Commands for Fast Movement Inhibit Postural Tone and Reflexes, and Prevent Habituation of Slow Reflexes

1979 ◽  
Vol 79 (1) ◽  
pp. 205-224
Author(s):  
JOHN Y. KUWADA ◽  
JEFFREY J. WINE
Keyword(s):  
Nervous System ◽  
Sensory Input ◽  
Neural Mechanisms ◽  
Simultaneous Occurrence ◽  
Neural Pathways ◽  
Escape Behaviour ◽  
Motor Neurones ◽  
Fast Movement ◽  
Postural Tone ◽  
Stimulation Of

Organized behaviour requires central neural mechanisms to prevent the simultaneous occurrence of incompatible movements. We investigated neural pathways in crayfish that suppress slow flexion of the abdomen during rapid flexions (‘tailflips’) produced by a separate set of muscles. The slow flexors are innervated in each half segment of the abdomen by five motor neurones and one peripheral inhibitor. In isolated preparations of the abdominal nervous system, stimulation of identified command neurones, which trigger tailflips in intact animals, inhibited spontaneous activity in the motor neurones to the slow flexors and excited the peripheral inhibitor. These effects are mediated by a population of interganglionic intemeurones interposed between the command cells and the slow flexor efferents. Slow flexor reflexes also were inhibited by escape commands. This inhibition includes pathways that act upon early stages of sensory input. As a result, habituation of reflexes, which normally is produced by repeated stimulation, is abolished if each sensory stimulus is preceded by a burst of impulses in the command neurone.

The whole-body withdrawal response of Lymnaea stagnalis. II. Activation of central motoneurones and muscles by sensory input

1991 ◽  
Vol 158 (1) ◽  
pp. 97-116 ◽  
Author(s):  
G. P. Ferguson ◽  
P. R. Benjamin
Keyword(s):  
Action Potentials ◽  
Sensory Input ◽  
Lymnaea Stagnalis ◽  
Intact Animal ◽  
The Body ◽  
Resting Potential ◽  
Whole Body ◽  
Withdrawal Response ◽  
Stimulation Of

The role of centrally located motoneurones in producing the whole-body withdrawal response of Lymnaea stagnalis (L.) was investigated. The motoneurones innervating the muscles used during whole-body withdrawal, the columellar muscle (CM) and the dorsal longitudinal muscle (DLM) were cells with a high resting potential (−60 to −70 mV) and thus a high threshold for spike initiation. In both semi-intact and isolated brain preparations these motoneurones showed very little spontaneous spike activity. When spontaneous firing was seen it could be correlated with the occurrence of two types of spontaneous excitatory postsynaptic potential (EPSP). One was a unitary EPSP that occasionally caused the initiation of single action potentials. The second was a larger-amplitude, long-duration (presumably compound) EPSP that caused the motoneurones to fire a burst of high-frequency action potentials. This second type of EPSP activity was associated with spontaneous longitudinal contractions of the body in semi-intact preparations. Tactile stimulation of the skin of Lymnaea evoked EPSPs in the CM and DLM motoneurones and in some other identified cells. These EPSPs summated and usually caused the motoneurone to fire action potentials, thus activating the withdrawal response muscles and causing longitudinal contraction of the semi-intact animal. Stimulating different areas of the body wall demonstrated that there was considerable sensory convergence on the side of the body ipsilateral to stimulation, but less on the contralateral side. Photic (light off) stimulation of the skin of Lymnaea also initiated EPSPs in CM and DLM motoneurones and in some other identified cells in the central nervous system (CNS). Cutting central nerves demonstrated that the reception of this sensory input was mediated by dermal photoreceptors distributed throughout the epidermis. The activation of the CM and DLM motoneurones by sensory input of the modalities that normally cause the whole-body withdrawal of the intact animal demonstrates that these motoneurones have the appropriate electrophysiological properties for the role of mediating whole-body withdrawal.

scholarly journals Superior Colliculus Control of Vibrissa Movements

2008 ◽  
Vol 100 (3) ◽  
pp. 1245-1254 ◽  
Author(s):  
Marie E. Hemelt ◽  
Asaf Keller
Keyword(s):  
Motor Cortex ◽  
Superior Colliculus ◽  
Sensory Input ◽  
Field Potential ◽  
Sensory Stimulation ◽  
Set Point ◽  
Sensory Inputs ◽  
Mystacial Vibrissae ◽  
Stimulation Of

This study tested the role of the superior colliculus in generating movements of the mystacial vibrissae—whisking. First, we compared the kinematics of whisking generated by the superior colliculus with those generated by the motor cortex. We found that in anesthetized rats, microstimulation of the colliculus evoked a sustained vibrissa protraction, whereas stimulation of motor cortex produced rhythmic protractions. Movements generated by the superior colliculus are independent of motor cortex and can be evoked at lower thresholds and shorter latencies than those generated by the motor cortex. Next we tested the hypothesis that the colliculus is acting as a simple reflex loop with the neurons that drive vibrissa movement receiving sensory input evoked by vibrissa contacts. We found that most tecto-facial neurons do not receive sensory input. Not only did these neurons not spike in response to sensory stimulation, but field potential analysis revealed that subthreshold sensory inputs do not overlap spatially with tecto-facial neurons. Together these findings suggest that the superior colliculus plays a pivotal role in vibrissa movement—regulating vibrissa set point and whisk amplitude—but does not function as a simple reflex loop. With the motor cortex controlling the whisking frequency, the superior colliculus control of set point and amplitude would account for the main parameters of voluntary whisking.

Stimulation of Ca(2+)-dependent exocytosis of the sperm acrosome by cAMP acting downstream of phospholipase A2

Reproduction ◽  
2000 ◽  
pp. 57-68 ◽  
Author(s):  
J Garde ◽  
ER Roldan
Keyword(s):  
Arachidonic Acid ◽  
Phospholipase A2 ◽  
Phospholipase C ◽  
Phosphodiesterase Inhibitors ◽  
Dibutyryl Camp ◽  
Camp Phosphodiesterase ◽  
Ram Sperm ◽  
Camp Formation ◽  
Stimulation Of

Spermatozoa undergo exocytosis in response to agonists that induce Ca2+ influx and, in turn, activation of phosphoinositidase C, phospholipase C, phospholipase A2, and cAMP formation. Since the role of cAMP downstream of Ca2+ influx is unknown, this study investigated whether cAMP modulates phospholipase C or phospholipase A2 using a ram sperm model stimulated with A23187 and Ca2+. Exposure to dibutyryl-cAMP, phosphodiesterase inhibitors or forskolin resulted in enhancement of exocytosis. However, the effect was not due to stimulation of phospholipase C or phospholipase A2: in spermatozoa prelabelled with [3H]palmitic acid or [14C]arachidonic acid, these reagents did not enhance [3H]diacylglycerol formation or [14C]arachidonic acid release. Spermatozoa were treated with the phospholipase A2 inhibitor aristolochic acid, and dibutyryl-cAMP to test whether cAMP acts downstream of phospholipase A2. Under these conditions, exocytosis did not occur in response to A23187 and Ca2+. However, inclusion of dibutyryl-cAMP and the phospholipase A2 metabolite lysophosphatidylcholine did result in exocytosis (at an extent similar to that seen when cells were treated with A23187/Ca2+ and without the inhibitor). Inclusion of lysophosphatidylcholine alone, without dibutyryl-cAMP, enhanced exocytosis to a lesser extent, demonstrating that cAMP requires a phospholipase A2 metabolite to stimulate the final stages of exocytosis. These results indicate that cAMP may act downstream of phospholipase A2, exerting a regulatory role in the exocytosis triggered by physiological agonists.

Presence, Environment, and Sound and the Role of Imagination

2019 ◽  
pp. 667-681
Author(s):  
Mark Grimshaw-Aagaard
Keyword(s):  
Computer Games ◽  
Virtual World ◽  
Actual World ◽  
Sensory Input ◽  
The World ◽  
Visual Dimension ◽  
The Creation ◽  
First Person Shooter ◽  
Selection Of

Mark Grimshaw-Aagaard addresses the role of sound in the creation of presence in virtual and actual worlds. He argues that imagination is a central part of the generation and selection of perceptual hypotheses—models of the world in which we can act—that emerge from what Grimshaw-Aagaard calls the “exo-environment” (the sensory input) and the “endo-environment” (the cognitive input). Grimshaw-Aagaard further divides the exo-environment into a primarily auditory and a primarily visual dimension and he deals with the actual world of his own apartment and the virtual world of first-person-shooter computer games in order to exemplify how we perceptually construct an environment that allows for the creation of presence.

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