scholarly journals Slow Active Potentials in Walking-Leg Motor Neurones Triggered by Non-Spiking Proprioceptive Afferents in the Crayfish

1986 ◽  
Vol 126 (1) ◽  
pp. 445-452
Author(s):  
KEITH T. SILLAR ◽  
ROBERT C. ELSON
Keyword(s):  
Neural Network ◽  
Nervous System ◽  
Motor Neurone ◽  
Pacifastacus Leniusculus ◽  
Intracellular Recordings ◽  
Synaptic Inputs ◽  
Rhythmic Motor ◽  
Motor Neurones ◽  
Receptor Organ ◽  
Proprioceptive Afferents

Intracellular recordings have been made from walking-leg motor neurones of the crayfish, Pacifastacus leniusculus, in isolated preparations of the thoracic ganglia. Some motor neurones display slow depolarizations that can drive bursts of spikes and resemble ‘plateau’ potentials described in other invertebrate and vertebrate neurones. Evidence is presented which suggests that the potentials are regenerative and endogenous to the motor neurones, and are not the result of feedback from a neural network. These potentials can be induced by synaptic inputs from the non-spiking afferent neurones of the thoracic-coxal muscle receptor organ, a basal limb proprioceptor. Reflex input from this receptor is augmented during the active depolarization of the motor neurone. The results are discussed in terms of the control of rhythmic motor output and the central modulation of reflexes in the crayfish's thoracic nervous system.

Patterned activation of unpaired median neurons during fictive crawling in manduca sexta larvae

1999 ◽  
Vol 202 (2) ◽  
pp. 103-113 ◽  
Author(s):  
R.M. Johnston ◽  
C. Consoulas ◽  
H. Pflüger ◽  
R.B. Levine
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Manduca Sexta ◽  
Motor Pattern ◽  
Intracellular Recordings ◽  
Subesophageal Ganglion ◽  
Synaptic Inputs ◽  
Functional Consequences ◽  
Manduca Sexta Larvae ◽  
Synaptic Drive

The unpaired median neurons are common to the segmental ganglia of many insects. Although some of the functional consequences of their activation, among them the release of octopamine to modulate muscle contraction, have been described, less is understood about how and when these neurons are recruited during movement. The present study demonstrates that peripherally projecting unpaired median neurons in the abdominal and thoracic ganglia of the larval tobacco hornworm Manduca sexta are recruited rhythmically during the fictive crawling motor activity that is produced by the isolated central nervous system in response to pilocarpine. Regardless of the muscles to which they project, the efferent unpaired median neurons in all segmental ganglia are depolarized together during the phase of the crawling cycle when the thoracic leg levator motoneurons are active. During fictive crawling, therefore, the unpaired median neurons are not necessarily active in synchrony with the muscles to which they project. The rhythmical synaptic drive of the efferent unpaired median neurons is derived, at least in part, from a source within the subesophageal ganglion, even when the motor pattern is evoked by exposing only the more posterior ganglia to pilocarpine. In pairwise intracellular recordings from unpaired median neurons in different ganglia, prominent excitatory postsynaptic potentials, which occur with an anterior-to-posterior delay in both neurons, are seen to underlie the rhythmic depolarizations. One model consistent with these findings is that one or more neurons within the subesophageal ganglion, which project posteriorly to the segmental ganglia and ordinarily provide unpatterned synaptic inputs to all efferent unpaired median neurons, become rhythmically active during fictive crawling in response to ascending information from the segmental pattern-generating network.

INTEGRATION OF POSITIVE AND NEGATIVE FEEDBACK LOOPS IN A CRAYFISH MUSCLE

1994 ◽  
Vol 187 (1) ◽  
pp. 305-313
Author(s):  
P Skorupski ◽  
P Vescovi ◽  
B Bush
Keyword(s):  
Negative Feedback ◽  
Positive Feedback ◽  
Motor Neurone ◽  
Chordotonal Organ ◽  
Negative Feedback Loops ◽  
Reflex Pathways ◽  
Motor Neurones ◽  
Receptor Organ ◽  
Group 2

It is now well established that in arthropods movement-related feedback may produce positive, as well as negative, feedback reflexes (Bassler, 1976; DiCaprio and Clarac, 1981; Skorupski and Sillar, 1986; Skorupski et al. 1992; Vedel, 1980; Zill, 1985). Usually the same motor neurones are involved in both negative feedback (resistance) reflex responses and positive feedback reflexes. Reflex reversal involves a shift in the pattern of central inputs to a motor neurone, for example from excitation to inhibition. In the crayfish, central modulation of reflexes has been described in some detail for two basal limb proprioceptors, the thoracocoxal muscle receptor organ (TCMRO) and the thoracocoxal chordotonal organ (TCCO) (Skorupski et al. 1992; Skorupski and Bush, 1992). Leg promotor motor neurones are excited by stretch of the TCMRO (which, in vivo, occurs on leg remotion) in a negative feedback reflex, but when this reflex reverses they are inhibited by the same stimulus. Release of the TCCO (which corresponds to leg promotion) excites some, but not all, promotor motor neurones in a positive feedback reflex. There are at least two ways in which the reflex control of a muscle may be modulated in this system. Firstly, inputs to motor neurones may be routed via alternative reflex pathways to produce different reflex outputs. Secondly, the pattern of inputs to a motor pool may be inhomogeneous, so that activation of different subgroups of the motor pool causes different outputs. Different crayfish promotor motor neurones are involved in different reflexes. On this basis, the motor neurones may be classified into at least two subgroups: those that are excited by the TCCO in a positive feedback reflex (group 1) and those that are not (group 2). Do these motor neurone subgroups have different effects on the promotor muscle, or is the output of the two promotor subgroups summed at the neuromuscular level? To address this question we recorded from the promotor nerve and muscle in a semi-intact preparation of the crayfish, Pacifastacus leniusculus. Adult male and female crayfish, 8-11 cm rostrum to tail, were decapitated and the tail, carapace and viscera removed. The sternal artery was cannulated and perfused with oxygenated crayfish saline, as described previously (Sillar and Skorupski, 1986).

Sensory and Motor Neurones Responsible for the Local Bending Response in Leeches

1982 ◽  
Vol 96 (1) ◽  
pp. 161-180 ◽  
Author(s):  
WILLIAM B. KRISTAN
Keyword(s):  
Body Wall ◽  
Longitudinal Muscle ◽  
Motor Neurone ◽  
Intracellular Recordings ◽  
Firing Rates ◽  
Macrobdella Decora ◽  
Motor Neurones ◽  
The Central Nervous System ◽  
P Cells ◽  
Bending Response

1. Intracellular recordings were made from identified mechanosensory neurones (T and P cells) and longitudinal muscle motor neurones of leeches Hirudo medicinalis and Macrobdella decora while the skin was electrically stimulated to produce local bending responses. 2. The stimulus intensity required to produce local bending was found to activate the mechanosensory neurones at physiological firing rates. For a given stimulation frequency, intracellular activation of the mechanosensory neurones produced the same local bending response as did skin stimulation. Hyperpolarization sufficient to block the propagation of the afferent impulses into the central nervous system eliminated the local bending response to skin stimulation. 3. Stimulating identified longitudinal muscle motor neurones at frequencies observed during the local bending response produced body wall movements similar to those seen in local bending. Hyperpolarization of the motor neurones to block impulse initiation abolished local bending. 4. Mechanosensory neurone to longitudinal muscle motor neurone connexions were demonstrated to be effective and reliable, but polysynaptic for all but the previously documented monosynaptic connexions from mechanosensory neurones onto the L motor neurone (Nicholls & Purves, 1970). 5. It is concluded that the previously identified mechanosensory and motor neurones are exclusively responsible for the local bending response.

scholarly journals Central Synaptic Coupling of Walking Leg Motor Neurones in the Crayfish: Implications for Sensorimotor Integration

1988 ◽  
Vol 140 (1) ◽  
pp. 355-379
Author(s):  
PETER SKORUPSKI ◽  
KEITH T. SILLAR
Keyword(s):  
Motor Control ◽  
Sensorimotor Integration ◽  
Afferent Input ◽  
Stretch Receptor ◽  
Motor Neurone ◽  
Synaptic Coupling ◽  
Muscle Receptor ◽  
Motor Neurones ◽  
Receptor Organ ◽  
Inhibitory Interactions

We present electrophysiological evidence for the presence of central output synapses on crayfish walking leg motor neurones. The effect of these central outputs is that a motor neurone can exert tonic graded control over other motor neurones without the requirement for spiking. Excitatory interactions among synergists and inhibitory interactions among antagonists are described. This central coupling among leg motor neurones profoundly affects their responses to afferent input from an identified stretch receptor, the thoracocoxal muscle receptor organ (TCMRO). Injecting current into a motor neurone can change the gain of TCMRO reflexes in other motor neurones. Some motor neurones are also capable of reversing the sign of TCMRO reflexes by inhibiting reflex firing of antagonists and facilitating reflex activity in synergists. The implications of these central interactions of motor neurones in motor control are discussed.

Convergent Chemical and Electrical Synaptic Inputs From Proprioceptive Afferents Onto an Identified Intersegmental Interneuron in the Crayfish

1997 ◽  
Vol 77 (5) ◽  
pp. 2826-2830 ◽  
Author(s):  
Toshiki Nagayama ◽  
Hitoshi Aonuma ◽  
Philip L. Newland
Keyword(s):  
Nervous System ◽  
Escape Behavior ◽  
Current Injection ◽  
Synaptic Delay ◽  
Chordotonal Organ ◽  
Electrical Transmission ◽  
Synaptic Inputs ◽  
Modes Of Transmission ◽  
Low Calcium ◽  
Proprioceptive Afferents

Nagayama, Toshiki, Hitoshi Aonuma, and Philip L. Newland. Convergent chemical and electrical synaptic inputs from proprioceptive afferents onto an identified intersegmental interneuron in the crayfish. J. Neurophysiol. 77: 2826–2830, 1997. Synaptic transmission between proprioceptive afferents from a chordotonal organ in the tailfan of the crayfish and an identified ascending interneuron, interneuron A, in the terminal abdominal ganglion was analyzed. Interneuron A is part of a disynaptic pathway from primary afferent neurons to the lateral giant interneuron involved in producing the characteristic ballistic escape behavior of crayfish. Interneuron A received short and long latency excitatory postsynaptic potentials (EPSPs) from chordotonal afferents. Short latency EPSPs occurred with little central synaptic delay, were unchanged by hyperpolarizing current injection of −2 nA, and remained at a constant amplitude when the nervous system was bathed in saline with a low calcium concentration or saline containing the nicotinic antagonist curare. These EPSPs are thus thought to be mediated by electrical transmission. Longer latency potentials were increased in amplitude by hyperpolarizing current injection, reduced in amplitude when the nervous system was bathed in low-calcium saline, and also reduced by bath application of saline containing curare. These potentials are thus thought to be mediated by chemical transmission. The functional significance of the dual modes of transmission at a key synapse in the escape circuitry is discussed.

Control of abdominal extension in the freely moving intact crayfish cherax destructor. II. Activity Of the superficial extensor motor neurones

1999 ◽  
Vol 202 (2) ◽  
pp. 183-191 ◽  
Author(s):  
B.J. Mccarthy ◽  
D.L. Macmillan
Keyword(s):  
Firing Rate ◽  
Motor Neurone ◽  
Full Extension ◽  
Sensory Neurone ◽  
Load Compensation ◽  
Muscle Receptor ◽  
Cherax Destructor ◽  
Motor Neurones ◽  
Receptor Organ ◽  
Freely Moving

The activity of the superficial extensor motor neurones was recorded during slow abdominal extension in the crayfish Cherax destructor. Postural extensions were evoked by lowering a platform from beneath the suspended crayfish. During extensions where the abdomen was physically blocked from achieving full extension, the largest superficial extensor motor neurone (SEMN6) fired at a higher rate than during unhindered extensions. Blocking a segment neighbouring that being examined also increased SEMN6 activity, demonstrating an intersegmental spread of the reflex. The increase in SEMN6 firing rate occurred in the absence of activity in the sensory neurone of the tonic muscle receptor organ, demonstrating that the tonic sensory neurone is not necessary for load compensation during these abdominal extensions in C. destructor. The findings support earlier evidence suggesting that other receptor systems can mediate load compensation in the abdomen of the crayfish.

Postsynaptic neuronal geometry and synaptic effectiveness

1987 ◽  
Vol 45 ◽  
pp. 690-697
Author(s):  
C.J. Wilson
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Synaptic Function ◽  
Postsynaptic Neuron ◽  
Synaptic Inputs ◽  
Partial Analysis ◽  
Postsynaptic Cell ◽  
Neuronal Geometry ◽  
The Relationship ◽  
Complex Scale

Most central nervous system neurons receive synaptic input from hundreds or thousands of other neurons, and the computational function of such neurons results from the interactions of inputs on a large and complex scale. In most situations that have yielded to a partial analysis, the synaptic inputs to a neuron are not alike in function, but rather belong to distinct categories that differ qualitatively in the nature of their effect on the postsynaptic cell, and quantitatively in the strength of their influence. Many factors have been demonstrated to contribute to synaptic function, but one of the simplest and best known of these is the geometry of the postsynaptic neuron. The fundamental nature of the relationship between neuronal shape and synaptic effectiveness was established on theoretical grounds prior to its experimental verification.

scholarly journals Multiplexed neurochemical transmission emulated using a dual-excitatory synaptic transistor

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Mingxue Ma ◽  
Yao Ni ◽  
Zirong Chi ◽  
Wanqing Meng ◽  
Haiyang Yu ◽  
...  
Keyword(s):  
Neural Network ◽  
Central Nervous System ◽  
Nervous System ◽  
Long Term Potentiation ◽  
Short Term ◽  
Term Potentiation ◽  
Binary Neural Network ◽  
Neuromorphic Systems ◽  
Human Brains

AbstractThe ability to emulate multiplexed neurochemical transmission is an important step toward mimicking complex brain activities. Glutamate and dopamine are neurotransmitters that regulate thinking and impulse signals independently or synergistically. However, emulation of such simultaneous neurotransmission is still challenging. Here we report design and fabrication of synaptic transistor that emulates multiplexed neurochemical transmission of glutamate and dopamine. The device can perform glutamate-induced long-term potentiation, dopamine-induced short-term potentiation, or co-release-induced depression under particular stimulus patterns. More importantly, a balanced ternary system that uses our ambipolar synaptic device backtrack input ‘true’, ‘false’ and ‘unknown’ logic signals; this process is more similar to the information processing in human brains than a traditional binary neural network. This work provides new insight for neuromorphic systems to establish new principles to reproduce the complexity of a mammalian central nervous system from simple basic units.

Central connections of sensory neurones from a hair plate proprioceptor in the thoraco-coxal joint of the locust.

1995 ◽  
Vol 198 (7) ◽  
pp. 1589-1601 ◽  
Author(s):  
F Kuenzi ◽  
M Burrows
Keyword(s):  
Stance Phase ◽  
Swing Phase ◽  
Motor Neurone ◽  
Sensory Neurone ◽  
Sensory Neurones ◽  
Selective Stimulation ◽  
Basal Joint ◽  
Motor Neurones ◽  
Individual Motor ◽  
Stimulation Of

The hair plate proprioceptors at the thoraco-coxal joint of insect limbs provide information about the movements of the most basal joint of the legs. The ventral coxal hair plate of a middle leg consists of group of 10-15 long hairs (70 microns) and 20-30 short hairs (30 microns). The long hairs are deflected by the trochantin as the leg is swung forward during the swing phase of walking, and their sensory neurones respond phasically during an imposed deflection and tonically if the deflection is maintained. Selective stimulation of the long hairs elicits a resistance reflex that rotates the coxa posteriorly and is similar to that occurring at the transition from the swing to the stance phase of walking. The motor neurones innervating the posterior rotator and adductor coxae muscles are excited, and those to the antagonistic anterior rotator muscle are inhibited. By contrast, selective stimulation of the short hairs leads only to a weak inhibition of the anterior rotator. The excitatory effects of the long hairs are mediated, in part, by direct connections between their sensory neurones and particular motor neurones. A spike in a sensory neurone elicits a short-latency depolarising postsynaptic potential (PSP) in posterior rotator and adductor motor neurones whose amplitude is enhanced by hyperpolarising current injected into the motor neurone. When the calcium in the saline is replaced with magnesium, the amplitude of the PSP is reduced gradually, and not abruptly as would be expected if an interneurone were interposed in the pathway. Several sensory neurones from long hairs converge to excite an individual motor neurone, evoking spikes in some motor neurones. The projections of the sensory neurones overlap with some of the branches of the motor neurones in the lateral association centre of the neuropile. It is suggested that these pathways would limit the extent of the swing phase of walking and contribute to the switch to the stance phase in a negative feedback loop that relieves the excitation of the hairs by rotating the coxa backwards.

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