scholarly journals Rhythmic patterns in the thoracic nerve cord of the stick insect induced by pilocarpine

1995 ◽  
Vol 198 (2) ◽  
pp. 435-456 ◽  
Author(s):  
A Büschges ◽  
J Schmitz ◽  
U Bässler
Keyword(s):  
Phase Transitions ◽  
Nerve Cord ◽  
Rhythmic Activity ◽  
Stick Insect ◽  
Burst Duration ◽  
Cycle Period ◽  
Muscarinic Agonist ◽  
Thoracic Nerve ◽  
Similar Range

Bath application of the muscarinic agonist pilocarpine onto the deafferented stick insect thoracic nerve cord induced long-lasting rhythmic activity in leg motoneurones. Rhythmicity was induced at concentrations as low as 1x10(-4) mol l-1 pilocarpine. The most stable rhythms were reliably elicited at concentrations from 2x10(-3) mol l-1 to 5x10(-3) mol l-1. Rhythmicity could be completely abolished by application of atropine. The rhythm in antagonistic motoneurone pools of the three proximal leg joints, the subcoxal, the coxo-trochanteral (CT) and the femoro-tibial (FT), was strictly alternating. In the subcoxal motoneurones, the rhythm was characterised by the retractor burst duration being correlated with cycle period, whereas the protractor burst duration was almost independent of it. The cycle periods of the rhythms in the subcoxal and CT motoneurone pools were in a similar range for a given preparation. In contrast, the rhythm exhibited by motoneurones supplying the FT joint often had about half the duration. The pilocarpine-induced rhythm was generated independently in each hemiganglion. There was no strict intersegmental coupling, although the protractor motoneurone pools of the three thoracic ganglia tended to be active in phase. There was no stereotyped cycle-to-cycle coupling in the activities of the motoneurone pools of the subcoxal joint, the CT joint and the FT joint in an isolated mesothoracic ganglion. However, three distinct 'spontaneous, recurrent patterns' (SRPs) of motoneuronal activity were reliably generated. Within each pattern, there was strong coupling of the activity of the motoneurone pools. The SRPs resembled the motor output during step-phase transitions in walking: for example, the most often generated SRP (SRP1) was exclusively exhibited coincident with a burst of the fast depressor trochanteris motoneurone. During this burst, there was a switch from subcoxal protractor to retractor activity after a constant latency. The activity of the FT joint extensor motoneurones was strongly decreased during SRP1. SRP1 thus qualitatively resembled the motoneuronal activity during the transition from swing to stance of the middle legs in forward walking. Hence, we refer to SRPs as 'fictive step-phase transitions'. In intact, restrained animals, application of pilocarpine also induced alternating activity in antagonistic motoneurone pools supplying the proximal leg joints. However, there were marked differences from the deafferented preparation. For example, SRP1 was not generated in the latter situation. However, if the ipsilateral main leg nerve was cut, SRP1s reliably occurred. Our results on the rhythmicity in leg motoneurone pools of deafferented preparations demonstrate central coupling in the activity of the leg motoneurones that might be incorporated into the generation of locomotion in vivo.

Rhythmic patterns evoked in locust leg motor neurons by the muscarinic agonist pilocarpine

1993 ◽  
Vol 69 (5) ◽  
pp. 1583-1595 ◽  
Author(s):  
S. Ryckebusch ◽  
G. Laurent
Keyword(s):  
Motor Neurons ◽  
Rhythmic Activity ◽  
Cycle Period ◽  
Muscarinic Agonist ◽  
Strongly Coupled ◽  
Weakly Coupled ◽  
Metathoracic Ganglion ◽  
Common Drive ◽  
Muscarinic Cholinergic

1. When an isolated metathoracic ganglion of the locust was superfused with the muscarinic cholinergic agonist pilocarpine, rhythmic activity was induced in leg motor neurons. The frequency of this induced rhythm increased approximately linearly from 0 to 0.2 Hz with concentrations of pilocarpine from 10(-5) to 10(-4) M. Rhythmic activity evoked by pilocarpine could be completely and reversibly blocked by 3 x 10(-5) M atropine, but was unaffected by 10(-4) M d-tubocurarine. 2. For each hemiganglion, the observed rhythm was characterized by two main phases: a levator phase, during which the anterior coxal rotator, levators of the trochanter, flexors of the tibia, and common inhibitory motor neurons were active; and a depressor phase, during which depressors of the trochanter, extensors of the tibia, and depressors of the tarsus were active. Activity in depressors of the trochanter followed the activity of the levators of the trochanter with a short, constant interburst latency. Activity in the levator of the tarsus spanned both phases. 3. The levator phase was short compared with the period (0.5-2 s, or 10-20% of the period) and did not depend on the period. The interval between the end of a levator burst and the beginning of the following one thus increased with cycle period. The depressor phase was more variable, and was usually shorter than the interval between successive levator bursts. 4. Motor neurons in a same pool often received common discrete synaptic potentials (e.g., levators of trochanter or extensors of tibia), suggesting common drive during the rhythm. Coactive motor neurons on opposite sides (such as left trochanteral depressors and right trochanteral levators), however, did not share obvious common postsynaptic potentials. Depolarization of a pool of motor neurons during its phase of activity was generally accompanied by hyperpolarization of its antagonist(s) on the same side. 5. Rhythmic activity was generally evoked in both hemiganglia of the metathoracic ganglion, but the intrinsic frequencies of the rhythms on the left and right were usually different. The activity of the levators of the trochanter on one side, however, was strongly coupled to that of the depressors of the trochanter on the other side. 6. The locomotory rhythm was weakly coupled to the ventilatory rhythm such that trochanteral levator activity on either side never occurred during the phase of spiracle opener activity corresponding to inspiration. 7. The rhythmic activity observed in vitro bears many similarities to patterns of neural and myographic activity recorded during walking. The similarities and differences are discussed.

Crawling motor patterns induced by pilocarpine in isolated larval nerve cords of Manduca sexta

1996 ◽  
Vol 76 (5) ◽  
pp. 3178-3195 ◽  
Author(s):  
R. M. Johnston ◽  
R. B. Levine
Keyword(s):  
Motor Activity ◽  
Motor Neurons ◽  
Nerve Cord ◽  
Body Wall ◽  
Motor Nerve ◽  
Rhythmic Activity ◽  
Cycle Period ◽  
Nerve Activity ◽  
Bursting Activity ◽  
Nerve Cords

1. Larval crawling is a bilaterally symmetrical behavior that involves an anterior moving wave of motor activity in the body wall muscles in conjunction with sequential movements of the abdominal prolegs and thoracic legs. The purpose of this study was to determine whether the larval CNS by itself and without phasic sensory feedback was capable of producing patterned activity associated with crawling. To establish the extent of similarity between the output of the isolated nerve cord and crawling, the motor activity produced in isolated larval nerve cords was compared with the motor activity from freely crawling larvae. 2. When exposed to the muscarinic receptor agonist pilocarpine (1.0 mM), isolated larval nerve cords produced long-lasting rhythmic activity in the motor neurons that supply the thoracic leg, abdominal body wall, and abdominal proleg muscles. The rhythmic activity evoked by pilocarpine was abolished reversibly and completely by bath application of the muscarinic-receptor antagonist atropine (0.01 mM) in conjunction with pilocarpine (1.0 mM), suggesting that the response was mediated by muscarinic-like acetylcholine receptors. 3. Similar to crawling in intact animals, the evoked activity in isolated nerve cords involved bilaterally symmetrical motor activity that progressed from the most posterior abdominal segment to the most anterior thoracic segment. The rhythmic activity in thoracic leg, abdominal proleg, and abdominal body wall motor neurons showed intrasegmental and intersegmental cycle-to-cycle coupling. The average cycle period for rhythmic activity in the isolated nerve cord was approximately 2.5 times slower than the cycle period for crawling in intact larvae, but not more variable. 4. Like crawling in intact animals, in isolated nerve cords, bursting activity in the dorsal body wall motor neurons occurred before activity in ventral/lateral body wall motor neurons within an abdominal segment. The evoked bursting activity recorded from the proleg nerve was superimposed on a high level of tonic activity. 5. In isolated nerve cords, bursts of activity in the thoracic leg levator/extensor motor neurons alternated with bursts of activity in the depressor/flexor motor neurons. The burst duration of the levator/extensor activity was brief and remained relatively steady as cycle period increased. The burst duration of the depressor/ flexor activity occupied the majority of an average cycle and increased as cycle period increased. The phase of both levator/extensor motor nerve activity and depressor/flexor motor nerve activity remained relatively stable over the entire range of cycle periods. The timing and patterning of thoracic leg motor neuron activity in isolated nerve cords quantitatively resembled thoracic leg motor activity in freely crawling larvae. 6. The rhythmic motor activity generated by an isolated larval nerve cord resembled a slower version of normal crawling in intact larvae. Because of the many similarities between activity induced in the isolated nerve cord and the muscle activity and movements of thoracic and abdominal segments during crawling, we concluded that central mechanisms can establish the timing and patterning of the crawling motor pattern and that crawling may reflect the output of a central pattern generating network.

Rhythmic swimming activity in neurones of the isolated nerve cord of the leech

1976 ◽  
Vol 65 (3) ◽  
pp. 643-668
Author(s):  
W. B. Kristan ◽  
R. L. Calabrese
Keyword(s):  
Nerve Cord ◽  
Body Shape ◽  
Sensory Input ◽  
Body Wall ◽  
Motor Neurone ◽  
The Body ◽  
Burst Duration ◽  
Cycle Period ◽  
Motor Neurones ◽  
Central Oscillator

1. Repeating bursts of motor neurone impulses have been recorded from the nerves of completely isolated nerve cords of the medicinal leech. The salient features of this burst rhythm are similar to those obtained in the semi-intact preparation during swimming. Hence the basic swimming rhythm is generated by a central oscillator. 2. Quantitative comparisons between the impulse patterns obtained from the isolated nerve cord and those obtained from a semi-intact preparation show that the variation in both dorsal to ventral motor neurone phasing and burst duration with swim cycle period differ in these two preparations. 3. The increase of intersegmental delay with period, which is a prominent feature of swimming behaviour of the intact animal, is not seen in either the semi-intact or isolated cord preparations. 4. In the semi-intact preparation, stretching the body wall or depolarizing an inhibitory motor neurone changes the burst duration of excitatory motor neurones in the same segment. In the isolated nerve cord, these manipulations also change the period of the swim cycle in the entire cord. 5. These comparisons suggest that sensory input stabilizes the centrally generated swimming rhythm, determines the phasing of the bursts of impulses from dorsal and ventral motor neurones, and matches the intersegmental delay to the cycle period so as to maintain a constant body shape at all rates of swimming.

Swimming rhythm in decerebrated, paralyzed stingrays: normal and abnormal coupling

1983 ◽  
Vol 50 (1) ◽  
pp. 178-191 ◽  
Author(s):  
M. H. Droge ◽  
R. B. Leonard
Keyword(s):  
Rhythmic Activity ◽  
Afferent Input ◽  
Burst Duration ◽  
Cycle Period ◽  
Fictive Locomotion ◽  
Spinal Segment ◽  
Swimming Pattern ◽  
Reciprocal Connections ◽  
Before And After ◽  
Stimulation Of

Rhythmic motoneuronal activity was recorded from decerebrated, paralyzed stingrays and compared with electromyograms recorded from the same animals. Before and after paralysis, a rostral-to-caudal sequence of alternation occurred between dorsal (elevator) and ventral (depressor) efferents. The swimming pattern was thus observed in the absence of phasic afferent input, and this constitutes fictive locomotion. After paralysis, both the intersegmental delay (time between activation at progressively caudal recording sites) and the burst duration remained linearly related to the swim cycle period. In many instances, neither the slope nor the intercept was significantly altered by immobilization. The intercepts all fell near the origin, indicating that the fictive rhythm remains constant phase coupled. Although the swimming rhythm was obtained after paralysis, some differences occurred. These included fewer and shorter spontaneous sequences, a greater range of cycle periods, and longer burst durations. During fictive swimming, the burst duration:cycle period ratio usually increased to 0.53 from 0.39 observed before paralysis. Therefore, the silent periods seen between burst discharges in antagonist efferents during movement were often absent after paralysis. Mechanical stimulation of the tail reduced both cycle periods and burst durations; however, the burst:cycle ratio remained greater than or equal to 0.50. The linear relation between burst duration and cycle period found for spontaneous sequences was not changed by stimulation of the tail. During fictive swimming the inter- and intrasegmental coupling that characterizes stingray swimming becomes labile. Abnormal coupling appears more often during sequences with long swim cycles. Intrasegmental coupling is tighter than intersegmental coupling at any cycle period. Rhythmic activity at one segmental level can be independent of activity at other levels. This suggests that multiple oscillator circuits exist that are not dependent on propriospinal circuits interconnecting different segments. Rhythmicity in elevator and depressor motoneurons is not dependent on reciprocal connections between the circuitry driving the motor nuclei. Therefore, separate oscillators for elevators and depressors appear to be present within one spinal segment.

Interjoint Coordination in the Stick Insect Leg-Control System: The Role of Positional Signaling

2003 ◽  
Vol 89 (3) ◽  
pp. 1245-1255 ◽  
Author(s):  
Dirk Bucher ◽  
Turgay Akay ◽  
Ralph A. DiCaprio ◽  
Ansgar Büschges
Keyword(s):  
Control System ◽  
Motor Activity ◽  
Joint Angle ◽  
Rhythmic Activity ◽  
Stick Insect ◽  
Spike Rate ◽  
Cycle Period ◽  
Walking Behavior ◽  
Interjoint Coordination

Interjoint coordination is essential for proper walking behavior in multi-jointed insect legs. We have shown previously that movement signals from the femur-tibia (FT) joint can shape motor activity of the adjacent coxa-trochanter (CT) joint in the stick insect, Carausius morosus. Here, we present data on the role of position signals from the FT-joint on activity generated in motoneurons (MNs) of the CT-joint. We show that the probability of occurrence of stance (with depression in the CT-joint) or swing movements (with levation in the CT-joint) at the start of walking sequences is influenced by the angle of the FT-joint in the resting animal. We tested the influence of FT-joint angle on pharmacologically induced rhythmic activity of CT-joint depressor (DprTr) and levator (LevTr) MNs. The burst duration, mean spike rate within bursts, and duty cycle for each MN pool were found to depend on FT position. For LevTr MNs, these parameters progressively increased as the FT-joint was moved from extension to flexion, and the opposite was true for DprTr MNs. The cycle period of CT-MN rhythmicity also depended on FT position. In addition, we sometimes observed that the motor output shifted completely to one MN pool at extreme positions, suggesting that the central rhythm-generating network for the CT-joint became locked in one phase. These results indicate that position signals from the FT-joint modulate rhythmic activity in CT-joint MNs partly by having access to central rhythm generating networks of the CT-joint.

Rhythmic Activity of Cat Pial Vessels in vivo

1981 ◽  
Vol 20 (6) ◽  
pp. 448-468 ◽  
Author(s):  
L.M. Auer ◽  
B. Gallhofer
Keyword(s):  
Rhythmic Activity ◽  
Pial Vessels

scholarly journals The AP2 clathrin adaptor protein complex regulates the abundance of GLR-1 glutamate receptors in the ventral nerve cord of Caenorhabditis elegans

2015 ◽  
Vol 26 (10) ◽  
pp. 1887-1900 ◽  
Author(s):  
Steven D. Garafalo ◽  
Eric S. Luth ◽  
Benjamin J. Moss ◽  
Michael I. Monteiro ◽  
Emily Malkin ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Secretory Pathway ◽  
Adaptor Protein ◽  
Intracellular Compartments ◽  
Clathrin Adaptor ◽  
Strength And Plasticity

Regulation of glutamate receptor (GluR) abundance at synapses by clathrin-mediated endocytosis can control synaptic strength and plasticity. We take advantage of viable, null mutations in subunits of the clathrin adaptor protein 2 (AP2) complex in Caenorhabditis elegans to characterize the in vivo role of AP2 in GluR trafficking. In contrast to our predictions for an endocytic adaptor, we found that levels of the GluR GLR-1 are decreased at synapses in the ventral nerve cord (VNC) of animals with mutations in the AP2 subunits APM-2/μ2, APA-2/α, or APS-2/σ2. Rescue experiments indicate that APM-2/μ2 functions in glr-1–expressing interneurons and the mature nervous system to promote GLR-1 levels in the VNC. Genetic analyses suggest that APM-2/μ2 acts upstream of GLR-1 endocytosis in the VNC. Consistent with this, GLR-1 accumulates in cell bodies of apm-2 mutants. However, GLR-1 does not appear to accumulate at the plasma membrane of the cell body as expected, but instead accumulates in intracellular compartments including Syntaxin-13– and RAB-14–labeled endosomes. This study reveals a novel role for the AP2 clathrin adaptor in promoting the abundance of GluRs at synapses in vivo, and implicates AP2 in the regulation of GluR trafficking at an early step in the secretory pathway.

scholarly journals Circadian modulation of neurons and astrocytes controls synaptic plasticity in hippocampal area CA1

2019 ◽  
Author(s):  
John P. McCauley ◽  
Maurice A. Petroccione ◽  
Lianna Y. D’Brant ◽  
Gabrielle C. Todd ◽  
Nurat Affinnih ◽  
...  
Keyword(s):  
Cognitive Processing ◽  
Temporal Dynamics ◽  
Rhythmic Activity ◽  
Surface Expression ◽  
Receptor Activation ◽  
Cellular Mechanisms ◽  
Functional Changes ◽  
Area Ca1 ◽  
Hippocampal Area

SummaryMost animal species operate according to a 24-hour period set by the suprachiasmatic nucleus (SCN) of the hypothalamus. The rhythmic activity of the SCN is known to modulate hippocampal-dependent memory processes, but the molecular and cellular mechanisms that account for this effect remain largely unknown. Here, we show that there are cell-type specific structural and functional changes that occur with circadian rhythmicity in neurons and astrocytes in hippocampal area CA1. Pyramidal neurons change the surface expression of NMDA receptors, whereas astrocytes change their proximity to synapses. Together, these phenomena alter glutamate clearance, receptor activation and integration of temporally clustered excitatory synaptic inputs, ultimately shaping hippocampal-dependent learningin vivo. We identify corticosterone as a key contributor to changes in synaptic strength. These findings identify important mechanisms through which neurons and astrocytes modify the molecular composition and structure of the synaptic environment, contribute to the local storage of information in the hippocampus and alter the temporal dynamics of cognitive processing.

Hormonal Control of the Malpighian Tubules of the Stick Insect, Carausius Morosus

1970 ◽  
Vol 52 (3) ◽  
pp. 653-665 ◽  
Author(s):  
DIANA E. M. PILCHER
Keyword(s):  
Stick Insect ◽  
Hormonal Control ◽  
The State ◽  
Malpighian Tubules ◽  
Suboesophageal Ganglion ◽  
Carausius Morosus ◽  
Corpora Cardiaca ◽  
Diuretic Hormone ◽  
The Brain

1. Urine secretion by isolated Malpighian tubules of Carausius is accelerated by a diuretic hormone which can be extracted from the brain, corpora cardiaca and suboesophageal ganglion. 2. The level of this hormone in the haemolymph varies according to the state of hydration of the insect. 3. The hormone is inactivated by the tubules, and a mechanism is proposed whereby the tubules might be controlled by the hormone in vivo.

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