Action of locust neuromodulatory neurons is coupled to specific motor patterns

1995 ◽  
Vol 74 (1) ◽  
pp. 347-357 ◽  
Author(s):  
M. Burrows ◽  
H. J. Pfluger
Keyword(s):  
Motor Neurons ◽  
Motor Pattern ◽  
Intracellular Recordings ◽  
Flexor Muscle ◽  
Motor Patterns ◽  
Specific Subset ◽  
Metathoracic Ganglion ◽  
Flexor Muscles ◽  
Dum Neurons ◽  
Dorsal Unpaired Median

1. Many muscles of the locust are supplied by dorsal unpaired median neurons (DUM neurons) that release octopamine and alter the contractions caused by spikes in motor neurons. To determine when these neuromodulatory neurons are normally activated during behaviour, intracellular recordings were made simultaneously from them and from identified motor neurons during the specific motor pattern that underlies kicking. A kick consists of a rapid and powerful extension of the tibia of one or both hind legs that is produced by a defined motor pattern. Only 3 identified DUM neurons of the 20 in the metathoracic ganglion spike during a kick, and they supply muscles involved in generating the kick. Their spikes occur in a distinctive and repeatable pattern that is closely linked to the pattern of spikes in the flexor and extensor tibiae motor neurons. When the extensor and flexor muscles cocontract, these three DUM neurons produce a burst of spikes at frequencies that can rise to 25 Hz, and with the number of spikes (3-15) related to the duration of this phase of the motor pattern. The spikes stop when the flexor muscle is inhibited and therefore before the tibia is extended rapidly. The other DUM neurons which supply muscles that are not directly involved in kicking are either inhibited or spike only sporadically. 2. The activation of a specific subset of DUM neurons during kicking may thus be timed to influence the action of the muscles that participate in this movement and appear to be controlled by the same circuits that determine the actions of the participating motor neurons. These modulatory neurons thus have specific individual actions in the control of movement.

Coupling of Efferent Neuromodulatory Neurons to Rhythmical Leg Motor Activity in the Locust

1998 ◽  
Vol 79 (1) ◽  
pp. 361-370 ◽  
Author(s):  
Sylvie Baudoux ◽  
Carsten Duch ◽  
Oliver T. Morris
Keyword(s):  
Motor Activity ◽  
Motor Neurons ◽  
Spike Activity ◽  
Motor Pattern ◽  
Rhythmic Activity ◽  
Motor Output ◽  
Variable Activity ◽  
Metathoracic Ganglion ◽  
Dum Neurons ◽  
Dorsal Unpaired Median

Baudoux, Sylvie, Carsten Duch, and Oliver T. Morris. Coupling of efferent neuromodulatory neurons to rhythmical leg motor activity in the locust. J. Neurophysiol. 79: 361–370, 1998. The spike activity of neuromodulatory dorsal unpaired median (DUM) neurons was analyzed during a pilocarpine-induced motor pattern in the locust. Paired intracellular recordings were made from these octopaminergic neurons during rhythmic activity in hindleg motor neurons evoked by applying pilocarpine to an isolated metathoracic ganglion. This motor pattern is characterized by two alternating phases: a levator phase, during which levator, flexor, and common inhibitor motor neurons spike, and a depressor phase, during which depressor and extensor motor neurons spike. Three different subpopulations of efferent DUM neurons could be distinguished during this rhythmical motor pattern according to their characteristic spike output. DUM 1 neurons, which in the intact animal do not innervate muscles involved in leg movements, showed no change apart from a general increase in spike frequency. DUM 3 and DUM 3,4 neurons produced the most variable activity but received frequent and sometimes pronounced hyperpolarizations that were often common to both recorded neurons. DUM 5 and DUM 3,4,5 neurons innervate muscles of the hindleg and showed rhythmical excitation leading to bursts of spikes during rhythmic activity of the motor neurons, which innervate these same muscles. Sometimes the motor output was coordinated across both sides of the ganglion so that there was alternating activity between levators of both sides. In these cases, the spikes of DUM 5 and DUM 3,4,5 neurons and the hyperpolarization of DUM 3 and DUM 3,4 neurons occurred at particular phases in the motor pattern. Our data demonstrate a central coupling of specific types of DUM neurons to a rhythmical motor pattern. Changes in the spike output of these particular efferent DUM neurons parallel changes in the motor output. The spike activity of DUM neurons thus may be controlled by the same circuits that determine the action of the motor neurons. Functional implications for real walking are discussed.

Innervation pattern of a pool of nine excitatory motor neurons in the flexor tibiae muscle of a locust hind leg

1998 ◽  
Vol 201 (12) ◽  
pp. 1885-1893 ◽  
Author(s):  
K Sasaki ◽  
M Burrows
Keyword(s):  
Motor Neurons ◽  
Muscle Fibres ◽  
Main Body ◽  
Intracellular Recordings ◽  
Innervation Pattern ◽  
Flexor Muscle ◽  
Fibre Bundles ◽  
Metathoracic Ganglion ◽  
Overlapping Sets ◽  
Individual Motor

The flexor tibiae muscle of a locust hind leg consists of 10-11 pairs of fibre bundles in the main body of the muscle and a distal pair of bundles that form the accessory flexor muscle, all of which insert onto a common tendon. It is much smaller than the antagonistic extensor tibiae muscle and yet it is innervated by nine excitatory motor neurons, compared with only two for the extensor. To determine the pattern of innervation within the muscle by individual motor neurons, branches of the nerve (N5B2) that supplies the different muscle bundles were backfilled to reveal somata in the metathoracic ganglion. This showed that different muscle bundles are innervated by different numbers of excitatory motor neurons. Physiological mapping of the innervation was then carried out by intracellular recordings from the somata of flexor motor neurons in the metathoracic ganglion using microelectrodes. Spikes were evoked in these neurons by the injection of current, and matching junctional potentials were sought in fibres throughout the muscle using a second intracellular electrode. Each motor neuron innervates only a restricted array of muscle fibres and, although some innervate a larger array than others, none innervates fibres throughout the muscle. Some motor neurons innervate only proximal fibres and others only more distal fibres, so that the most proximal and most distal bundles of muscle fibres are innervated by non-overlapping sets of motor neurons. More motor neurons innervate proximal bundles than distal ones, and there are some asymmetries in the number of motor neurons innervating corresponding bundles on either side of the tendon. Individual motor neurons cause slow, fast or intermediate movements of the tibia, but their patterns of innervation overlap in the different muscle bundles. Furthermore, individual muscle fibres may also be innervated by motor neurons with different properties.

Peptidergic modulation of a multioscillator system in the lobster. I. Activation of the cardiac sac motor pattern by the neuropeptides proctolin and red pigment-concentrating hormone

1989 ◽  
Vol 61 (4) ◽  
pp. 833-844 ◽  
Author(s):  
P. S. Dickinson ◽  
E. Marder
Keyword(s):  
Nervous System ◽  
Motor Neurons ◽  
Motor Pattern ◽  
Stomatogastric Ganglion ◽  
Red Pigment ◽  
Stomatogastric Nervous System ◽  
Two Phase ◽  
Motor Patterns ◽  
Neuronal Element

1. The cardiac sac motor pattern consists of slow and irregular impulse bursts in the motor neurons [cardiac sac dilator 1 and 2 (CD1 and CD2)] that innervate the dilator muscles of the cardiac sac region of the crustacean foregut. 2. The effects of the peptides, proctolin and red pigment-concentrating hormone (RPCH), on the cardiac sac motor patterns produced by in vitro preparations of the combined stomatogastric nervous system [the stomatogastric ganglion (STG), the paired commissural ganglia (CGs), and the oesophageal ganglion (OG)] were studied. 3. Bath applications of either RPCH or proctolin activated the cardiac sac motor pattern when this motor pattern was not already active and increased the frequency of the cardiac sac motor pattern in slowly active preparations. 4. The somata of CD1 and CD2 are located in the esophageal and stomatogastric ganglia, respectively. Both neurons project to all four of the ganglia of the stomatogastric nervous system. RPCH elicited cardiac sac motor patterns when applied to any region of the stomatogastric nervous system, suggesting a distributed pattern generating network with multiple sites of modulation. 5. The anterior median (AM) neuron innervates the constrictor muscles of the cardiac sac. The AM usually functions as a part of the gastric mill pattern generator. However, when the cardiac sac is activated by RPCH applied to the stomatogastric ganglion, the AM neuron becomes active in antiphase with the cardiac sac dilator bursts. This converts the cardiac sac motor pattern from a one-phase rhythm to a two-phase rhythm. 6. These data show that a neuropeptide can cause a neuronal element to switch from being solely a component of one neuronal circuit to functioning in a second one as well. This example shows that peptidergic "reconfiguration" of neuronal networks can produce substantial changes in the behavior of associated neurons.

Modulation of the crayfish swimmeret rhythm by octopamine and the neuropeptide proctolin

1987 ◽  
Vol 58 (3) ◽  
pp. 584-597 ◽  
Author(s):  
B. Mulloney ◽  
L. D. Acevedo ◽  
A. G. Bradbury
Keyword(s):  
Spontaneous Activity ◽  
Motor Neurons ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Motor Pattern ◽  
Threshold Concentration ◽  
Power Stroke ◽  
Motor Patterns ◽  
Dose Dependent ◽  
Characteristic Motor

1. The swimmeret system can be excited by perfusing the neuropeptide proctolin through the isolated ventral nerve cord of the crayfish. Previously silent preparations begin to generate a characteristic motor pattern, the swimmeret rhythm, in the nerves that innervate the swimmerets. The response to proctolin is dose dependent and reversible. The threshold concentration of proctolin perfused through the ventral artery is approximately 10(-8) M. The EC50 is 1.6 X 10(-6) M. 2. Proctolin-induced motor patterns have periods and phases similar to those of spontaneously generated motor patterns. The durations of the bursts of impulses in power-stroke motor neurons generated in the presence of proctolin are, however, significantly longer than those that occur during spontaneous activity. 3. DL-Octopamine inhibits the swimmeret system, both when the system is spontaneously active and when it has been excited by proctolin. The inhibition by octopamine is dose dependent and reversible. The threshold for inhibition is approximately 10(-6) M, and the EC50 is approximately 5 X 10(-5) M. 4. Octopamine's effect is mimicked by its agonists, synephrine and norepinephrine. Synephrine has a lower threshold concentration than does octopamine, but norepinephrine is much less effective than octopamine. 5. Octopamine's inhibition is partially blocked by an antagonist, phentolamine. 6. Phentolamine also blocks inhibition of the swimmeret system by inhibitory command interneurons. This block is dose dependent and can be partially overcome by stimulating the command interneurons at higher frequencies. 7. Perfusion with 11 other suspected crustacean neurotransmitters and transmitter analogues did not similarly excite or inhibit the swimmeret system, so we suggest that proctolin and octopamine are transmitters used by the neurons that normally control expression of the swimmeret rhythm.

Interneuronal and motor patterns during crawling behavior of semi-intact leeches.

1997 ◽  
Vol 200 (9) ◽  
pp. 1369-1381 ◽  
Author(s):  
A P Baader
Keyword(s):  
Motor Neurons ◽  
Behavior Pattern ◽  
Activity Patterns ◽  
Medicinal Leech ◽  
Intracellular Recordings ◽  
Motor Patterns ◽  
Potential Oscillations ◽  
Different Types ◽  
Inhibitory Motor Neurons ◽  
Membrane Potential Oscillations

Semi-intact tethered preparations were used to characterize neuronal activity patterns in midbody ganglia of the medicinal leech during crawling. Extra- and intracellular recordings were obtained from identified interneurons and from motor neurons of the longitudinal and circular muscles during crawling episodes. Coordinated activities of nine excitatory and inhibitory motor neurons of the longitudinal and circular muscles were recorded during the appropriate phases of crawling. Thus, during crawling, the leech uses motor output components known to contribute to other types of behavior, such as swimming or the shortening/local bending reflex. Interneurons with identified functions in these other types of behavior exhibit membrane potential oscillations that are in phase with the behavior pattern. Therefore, the recruitment of neuronal network elements during several types of behavior occurs not only at the motor neuron level but also involves interneurons. This applies even to some interneurons that were previously thought to have dedicated functions (such as cells 204 and 208 and the S cell). The function of neuronal circuitries in producing different types of behavior with a limited number of neurons is discussed.

Variations in Motor Patterns During Fictive Rostral Scratching in the Turtle: Knee-Related Deletions

2004 ◽  
Vol 91 (5) ◽  
pp. 2380-2384 ◽  
Author(s):  
Paul S. G. Stein ◽  
Susan Daniels-McQueen
Keyword(s):  
Motor Neuron ◽  
Motor Neurons ◽  
Activity Patterns ◽  
Motor Pattern ◽  
Knee Extensor ◽  
Reciprocal Inhibition ◽  
Knee Extensors ◽  
Motor Patterns ◽  
Knee Flexor ◽  
Hip Flexor

Agonist motor neurons usually alternate between activity and quiescence during normal rhythmic behavior; antagonist motor neurons are usually active during agonist motor neuron quiescence. During an antagonist deletion, a naturally occurring motor-pattern variation, there is no antagonist activity and no quiescence between successive bursts of agonist activity. Motor neuron recordings of normal fictive rostral scratching in the turtle displayed rhythmic alternation between activity and quiescence for hip flexors, knee flexors, and knee extensors. Knee-flexor activity occurred during knee-extensor quiescence. During a hip-extensor deletion, a variation of rostral scratching, rhythmic hip-flexor bursts occurred without intervening hip-flexor quiescence. There were 3 distinct patterns of knee motor activity during the cycle before or after a hip-extensor deletion. In most cycles, there was knee flexor-extensor rhythmic alternation. In some cycles, termed knee-flexor deletions, there was no knee-flexor activity and rhythmic knee-extensor bursts occurred without intervening knee-extensor quiescence. In other cycles, termed knee-extensor deletions, there was no knee-extensor activity and rhythmic knee-flexor bursts occurred without intervening knee-flexor quiescence. The concept of a module refers to a population of motor neurons and interneurons with similar activity patterns; interneurons in a module coordinate agonist and antagonist motor neuron activities, either with excitation of agonist motor neurons and interneurons, or with inhibition of antagonist motor neurons and interneurons. Previous studies of hip-extensor deletions support the concept of a rhythmogenic hip-flexor module. The knee-related deletions described here support the concept of rhythmogenic knee-flexor and knee-extensor modules linked by reciprocal inhibition.

scholarly journals Amine Modulation of Glutamate Responses From Pyloric Motor Neurons in Lobster Stomatogastric Ganglion

1997 ◽  
Vol 78 (6) ◽  
pp. 3210-3221 ◽  
Author(s):  
Bruce R. Johnson ◽  
Ronald M. Harris-Warrick
Keyword(s):  
Synaptic Transmission ◽  
Motor Neurons ◽  
Motor Pattern ◽  
Input Resistance ◽  
Synaptic Strength ◽  
Stomatogastric Ganglion ◽  
Ionic Conductance ◽  
Motor Patterns ◽  
Pyloric Network ◽  
Pyloric Dilator

Johnson, Bruce R. and Ronald M. Harris-Warrick. Amine modulation of glutamate responses from pyloric motor neurons in lobster stomatogastric ganglion. J. Neurophysiol. 78: 3210–3221, 1997. The amines dopamine (DA), serotonin (5-HT), and octopamine (Oct) each elicit a distinctive motor pattern from a quiescent pyloric network in the lobster stomatogastric ganglion (STG). We previously have demonstrated that these amines alter the synaptic strength at multiple, distributed sites within the pyloric network that could contribute to the amine-induced motor patterns. Here, we examined the postsynaptic contribution to these changes in synaptic strength by determining how the amines modify responses of pyloric motor neurons to glutamate (Glu), one of the network transmitters, applied iontophoretically into the STG neuropil. Dopamine reduced the Glu responses of the pyloric dilator (PD), ventricular dilator (VD), and inferior cardiac (IC) neurons and enhanced the Glu responses of the lateral pyloric (LP) and pyloric constrictor (PY) neurons. The only effect of 5-HT was to reduce the Glu response of the VD neuron. Oct enhanced the Glu responses of the LP and PY neurons but did not affect the PD, VD, and IC responses. We also examined amine effects on the depolarizing responses to iontophoresed acetylcholine (ACh) in the PD and VD and found that they paralleled the amine effects on Glu responses in these neurons. This suggests that amine modulation of PD and VD responses to Glu and ACh may be explained by general changes in the ionic conductance of these neurons. We compare our results with our earlier work describing amine effects on synaptic strength and input resistance to show that amines act at both pre- and postsynaptic sites to modify graded synaptic transmission in the pyloric network.

scholarly journals Imaging fictive locomotor patterns in larval Drosophila

2015 ◽  
Vol 114 (5) ◽  
pp. 2564-2577 ◽  
Author(s):  
Stefan R. Pulver ◽  
Timothy G. Bayley ◽  
Adam L. Taylor ◽  
Jimena Berni ◽  
Michael Bate ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Imaging Techniques ◽  
Motor Pattern ◽  
Pattern Generation ◽  
Motor Patterns ◽  
Posterior Direction ◽  
Muscle Groups ◽  
Locomotor Patterns ◽  
Left Right Asymmetry ◽  
The Brain

We have established a preparation in larval Drosophila to monitor fictive locomotion simultaneously across abdominal and thoracic segments of the isolated CNS with genetically encoded Ca2+ indicators. The Ca2+ signals closely followed spiking activity measured electrophysiologically in nerve roots. Three motor patterns are analyzed. Two comprise waves of Ca2+ signals that progress along the longitudinal body axis in a posterior-to-anterior or anterior-to-posterior direction. These waves had statistically indistinguishable intersegmental phase delays compared with segmental contractions during forward and backward crawling behavior, despite being ∼10 times slower. During these waves, motor neurons of the dorsal longitudinal and transverse muscles were active in the same order as the muscle groups are recruited during crawling behavior. A third fictive motor pattern exhibits a left-right asymmetry across segments and bears similarities with turning behavior in intact larvae, occurring equally frequently and involving asymmetry in the same segments. Ablation of the segments in which forward and backward waves of Ca2+ signals were normally initiated did not eliminate production of Ca2+ waves. When the brain and subesophageal ganglion (SOG) were removed, the remaining ganglia retained the ability to produce both forward and backward waves of motor activity, although the speed and frequency of waves changed. Bilateral asymmetry of activity was reduced when the brain was removed and abolished when the SOG was removed. This work paves the way to studying the neural and genetic underpinnings of segmentally coordinated motor pattern generation in Drosophila with imaging techniques.

Central input to primary afferent neurons in crayfish, Pacifastacus leniusculus, is correlated with rhythmic motor output of thoracic ganglia

1986 ◽  
Vol 55 (4) ◽  
pp. 678-688 ◽  
Author(s):  
K. T. Sillar ◽  
P. Skorupski
Keyword(s):  
Motor Neurons ◽  
Motor Pattern ◽  
Reversal Potential ◽  
Motor Output ◽  
Resting Membrane Potential ◽  
Strongly Correlated ◽  
Motor Patterns ◽  
Thoracic Ganglia ◽  
Rhythmic Motor ◽  
Receptor Organ

A preparation is described in which the thoracic ganglia of the crayfish are isolated together with the thoracocoxal muscle receptor organ (TCMRO) of the fourth leg. This preparation allows intracellular analysis of both centrally generated and reflex activity in leg motor neurons (MNs). The isolated thoracic ganglia can spontaneously generate a rhythmic motor pattern resembling that used during forward walking (Fig. 4). This involves the reciprocal activity of promotor and remotor MNs, with levator MNs firing in phase with promotor bursts. Stretch of the TCMRO in quiescent preparations evokes a resistance reflex in promotor MNs (Fig. 6). In more active preparations the response is variable and often becomes an assistance reflex, with excitation of remotor MNs on stretch (Fig. 7). When rhythmic motor patterns occur, the neuropilar processes of the S and T fibers receive central inputs that are strongly correlated with the oscillatory drive to the MNs and probably have the same origin (Figs. 8 and 9). Central inputs to the S and T fibers occur in opposite phases within a cycle of rhythmic motor output. The S fiber is depolarized in phase with promotor MNs and the T fiber in phase with remotor activity. The input to the T fiber is shown to be a chemical synaptic drive that has a reversal potential approximately 14 mV more depolarized than the fiber's resting membrane potential. This input substantially modulates the amplitude and waveform of passively propagated receptor potentials generated by TCMRO stretch (Fig. 11). It is argued that the central inputs to the TCMRO afferents will modulate proprioceptive feedback resulting from voluntary movements.

Analysis and modeling of the multisegmental coordination of shortening behavior in the medicinal leech. II. Role of identified interneurons

1992 ◽  
Vol 68 (5) ◽  
pp. 1693-1707 ◽  
Author(s):  
G. Wittenberg ◽  
W. B. Kristan
Keyword(s):  
Nervous System ◽  
Motor Neurons ◽  
Motor Pattern ◽  
Back Propagation ◽  
Motor Output ◽  
Sensory Cells ◽  
Motor Patterns ◽  
Trained Neural Network ◽  
Motor Effects

1. Mechanical stimulation of the leech, Hirudo medicinalis, elicits withdrawal behavior that has two components: local bending in the segment stimulated and shortening in outlying segments. Local bending is characterized by excitation of longitudinal muscle on one side of the segment and inhibition on the other side. In shortening, all longitudinal muscles are excited. We wished to understand how these distinct motor patterns are produced by a nervous system with segmentally iterated neurons, a configuration that places some limitations on the complexity of connection patterns. 2. We searched for neurons in the segmental nervous system that subserved shortening behavior, expecting to find at least one interneuron in each segment that was involved in shortening behavior exclusively. We found instead that all interneurons involved in shortening are also involved in local bending, and no individual interneuron can completely account for shortening. 3. The motor output caused by individual identified interneurons is not entirely consistent with the shortening motor output pattern. For instance, one interneuron, cell 115, has the same pattern of motor effects from segment to segment, causing excitation of dorsal excitatory motor neurons and inhibition of ventral excitatory motor neurons. These effects would cause dorsal local bending, not shortening, in a few segments. Only one interneuron, cell 125, has motor effects that would cause shortening. 4. Individual interneurons were hyperpolarized while single sensory cells were stimulated, to quantify the contributions of individual interneurons to the observed motor pattern. Interneurons 115 and 125, and the inhibitory motor neuron, cell 1, were found to have significant roles in producing the shortening motor output. 5. A quantitative estimate of the role of each interneuron type showed that the identified interneurons account for most of the excitation of dorsal motor neurons, but for very little of the excitation of ventral motor neurons. This predicts that at least one additional interneuron type remains to be identified, one that would provide excitation to ventral motor neurons in several segments. 6. A back-propagation trained neural network model was constructed to predict the connections of the as yet unidentified interneurons. To match the known properties of interneurons, it was necessary to include a segmental similarity constraint in the training algorithm for segmentally iterated model neurons. The modeled networks predicted that there are at least two kinds of interneurons yet to be found. Also, the modeling showed that interneurons can have input and output patterns that differ very little from segment to segment but yet produce major differences in the motor output.

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