Control of abdominal extension in the freely moving intact crayfish cherax destructor. I. Activity Of the tonic stretch receptor

1999 ◽  
Vol 202 (2) ◽  
pp. 171-181 ◽  
Author(s):  
B.J. Mccarthy ◽  
D.L. Macmillan
Keyword(s):  
Activity Pattern ◽  
Stretch Receptor ◽  
Sensory Neurone ◽  
Muscle Receptor ◽  
Cherax Destructor ◽  
Tonic Muscle ◽  
Receptor Organ ◽  
Servo Loop ◽  
Freely Behaving ◽  
Freely Moving

Electrical recordings were made from the sensory neurone of the tonic muscle receptor organ in the abdomen of the intact, freely behaving crayfish Cherax destructor. Slow extensions of the abdomen were evoked by lowering a platform from beneath the suspended crayfish, and the movements and tonic sensory neurone activity were video-recorded simultaneously. The recordings showed that the tonic sensory neurone was active when the abdomen was fully flexed prior to the extension. When the extension began, however, the sensory neurone ceased firing shortly after movement was detected, irrespective of the load applied to the abdomen. When the abdomen was physically blocked from extending fully, the sensory neurone did not fire. The tonic muscle receptor organ is considered to be the length-detecting sensor for a load-compensating servo-loop, but the results demonstrate that its activity pattern during extensions evoked by a platform-drop in C. destructor are not consistent with that role.

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.

The role of the muscle receptor organ in the control of abdominal extension in the crayfish, Cherax destructor

1995 ◽  
Vol 198 (11) ◽  
pp. 2253-2259 ◽  
Author(s):  
B Mccarthy ◽  
D Macmillan
Keyword(s):  
Constant Load ◽  
Abdominal Muscle ◽  
Muscle Receptor ◽  
Complete Extension ◽  
Cherax Destructor ◽  
Before And After ◽  
Error Detector ◽  
Receptor Organ ◽  
Servo Loop

A platform was lowered from beneath suspended crayfish, Cherax destructor, to evoke slow abdominal extension. The movements were filmed and the length between segments plotted as a function of time. Unlike abdominal flexion, which starts posteriorly and progresses anteriorly, extension occurs at all joints simultaneously. Although the duration of extension varied from trial to trial for an individual, the movement was organised in a stereotyped manner: the abdomen achieved a consistent position for any given proportion of the time for complete extension. We examined the role of the abdominal muscle receptor organs (MROs) in extension by cutting the nerves of selected MROs to abolish their input. The extension movement was measured before and after nerve section for animals with either unloaded or loaded abdomens. Removal of MRO input had no significant effect on extension of the unloaded abdomen. In animals with a loaded abdomen, the extension at joints spanned by sectioned MROs was slowed, whereas that at joints with intact MROs was not. The findings are consistent with the hypothesis that the MRO is an error detector in a servo-loop controlling abdominal position. The results provide the first demonstration that this load-compensating reflex loop operates during naturally evoked extension of the abdomen under constant load.

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.

scholarly journals The Actions of Proctolin, Octopamine and Serotonin on Crustacean Proprioceptors Show Species and Neurone Specificity

1990 ◽  
Vol 152 (1) ◽  
pp. 485-504 ◽  
Author(s):  
VALERIE M. PASZTOR ◽  
DAVID L. MACMILLAN
Keyword(s):  
General Property ◽  
Receptor Potential ◽  
Homarus Americanus ◽  
Primary Afferents ◽  
Stretch Receptor ◽  
The Other ◽  
Broad Distribution ◽  
Cherax Destructor ◽  
Receptor Organ ◽  
Comparative Survey

A comparative survey is presented of the responsiveness of crustacean mechanoreceptors to the neurohormones proctolin, octopamine and serotonin. Seven identifiable primary afferents were examined in the crayfish Cherax destructor and the lobster Homarus americanus: three from the oval organ (OO) of the second maxilla, two from the non-spiking stretch receptor (NSSR) of the swimmeret and two from the muscle receptor organ (MRO) of the abdomen. Proctolin modulation was observed in 10 of the 14 fibres tested and was invariably potentiating, resulting in enhanced receptor potential amplitudes and increased firing. Octopamine and serotonin each modulated 8 of the 14 fibres and their effects were excitatory or depressive depending upon the target fibre. In the latter case the receptor potentials became attenuated, often to subthreshold levels, with loss of spiking. A comparison of results from Cherax with those of Homarus shows that there is species specificity in the responses of homologous neurones. Neurohormones that are excitatory in one species may be ineffective or depressive in the other. The broad distribution of modulatory effects observed here suggests that sensitivity to biogenic amines and peptides is a general property of proprioceptors.

A new muscle receptor organ in the antenna of the rock lobster Palinurus vulgaris : mechanical, muscular and proprioceptive organization of the two proximal joints J0 and J1

1983 ◽  
Vol 218 (1210) ◽  
pp. 95-110 ◽  
Keyword(s):  
Anterior Part ◽  
Proximal Part ◽  
The Other ◽  
Chordotonal Organ ◽  
Excitatory Postsynaptic Potentials ◽  
Rock Lobster ◽  
Postsynaptic Potentials ◽  
Muscle Receptor ◽  
Physiological Properties ◽  
Receptor Organ

(i) Following previous work on the morphological and physiological properties of the two distal joints (J2, J3) of the atenna of the rock lobster Palinurus vulgaris , the mechanical, muscular and proprioceptive organization of the two proximal joints between the antennal segments S1 and S2 (J1) and between S1 and the cephalothorax (J0) have now been studied. (ii) Articulated by two classical condyles, J1 moves in a mediolateral plane. One external rotator muscle (ER) and three internal rotator muscles (IR1, IR2, IR3) subserve its movements. J0 is articulated by two different systems: a classical ventrolateral condyle and a complex sliding system constituted by special cuticular structures on the dorsomedial side of the S1 segment and on the rostrum between the two antennae. J0 moves in the dorsoventral plane by means of a levator muscle (Lm) and a depressor muscle (Dm). A third muscle, the lateral tractor muscle (LTm), associated with J0 and lying obliquely across S1, may modulate the level of friction between the S1 segment and the rostrum. (iii) Proprioception in J1 is achieved by a muscle receptor organ AMCO-J1 (antennal myochordotonal organ for the J1 joint) associating a small accessory muscle (S1.am) located in the proximal part of the S1 segment and a chordotonal organ inserted proximally on the S1.am muscle and distally on the S2 segment. J0 proprioception is ensured by a simple chordotonal organ (CO-J0) located in the anterior part of the cephalothorax. (iv) The S1.am muscle is innervated by three motoneurons characterized by their very small diameters and inducing respectively tonic excitatory postsynaptic potentials, phasic excitatory postsynaptic potentials and inhibitory postsynaptic potentials. Anatomical and physiological observations suggest functional correlation between S1.am and IR1 motor innervation. (v) Mechanical and muscular organization of J0 and J1 are compared with that of the other joints of the antenna. The properties of the AMCO-J1 proprioceptor are discussed in relation to the other muscle receptor organs described in crustaceans.

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