Fine structural localization of acetylcholinesterase in sensory and motor neurons of the muscle receptor organ inHomarus

1970 ◽  
Vol 140 (4) ◽  
pp. 399-419 ◽  
Author(s):  
Joseph B. Nadol ◽  
Miro Brzin ◽  
A. J. Darin de Lorenzo
Keyword(s):  
Motor Neurons ◽  
Structural Localization ◽  
Muscle Receptor ◽  
Receptor Organ

Phase-dependent reversal of reflexes mediated by the thoracocoxal muscle receptor organ in the crayfish, Pacifastacus leniusculus

1986 ◽  
Vol 55 (4) ◽  
pp. 689-695 ◽  
Author(s):  
P. Skorupski ◽  
K. T. Sillar
Keyword(s):  
Motor Neurons ◽  
Negative Feedback ◽  
Positive Feedback ◽  
Motor Output ◽  
Dependent Manner ◽  
Muscle Receptor ◽  
Reflex Pathways ◽  
Receptor Organ ◽  
Positive And Negative Feedback ◽  
Central Excitability

Both negative feedback, resistance reflexes and positive feedback, assistance reflexes are mediated by the thoracocoxal muscle receptor organ (TCMRO) in the crayfish, depending on the central excitability of the preparation. In this paper we present evidence that the velocity-sensitive afferent T fiber of the TCMRO may elicit either resistance or assistance reflexes in different preparations. In preparations displaying assistance reflexes, the S and T fibers of the TCMRO exert reciprocal effects on leg motor neurons (MNs). The S fiber excites promotor MNs (negative feedback) and inhibits remotor MNs, the T fiber excites remotor MNs (positive feedback) and inhibits promotor MNs. During reciprocal motor output of promotor and remotor MNs, reflexes mediated by the TCMRO are modulated in a phase-dependent manner. The TCMRO excites promotor MNs during their active phases (negative feedback) but inhibits them during their reciprocal phases. Remotor MNs are excited by the TCMRO during their active phases (positive feedback). It is proposed that depolarizing central inputs that occur in the S and T fibers at opposite phases of the motor output cycle (21) facilitate the output effects of each afferent in alternation, effectively mediating a phase-dependent shift between the effects of one afferent and the other. The implications of central modulation of reflex pathways and the possible functions of positive and negative feedback reflexes during locomotion are discussed.

scholarly journals Abdominal postural motor responses initiated by the muscle receptor organ in lobster depend upon centrally generated motor activity

1992 ◽  
Vol 162 (1) ◽  
pp. 167-183
Author(s):  
S. C. Sukhdeo ◽  
C. H. Page
Keyword(s):  
Motor Activity ◽  
Motor Neurons ◽  
Procambarus Clarkii ◽  
Homarus Americanus ◽  
Abdominal Muscle ◽  
Sensory Response ◽  
Reflex Responses ◽  
Muscle Receptor ◽  
Postural Reflex ◽  
Receptor Organ

1. Stretch stimulation of the abdominal muscle receptor organ of the lobster Homarus americanus initiated spike discharge of its tonic sensory neuron (SR1). This sensory response evoked a series of tonic postural reflex responses in the motor neurons that innervate the superficial extensor and flexor muscles of the abdominal postural system. The type of motor response depended on whether a flexion or extension pattern of spontaneous activity was being generated by the postural efferents. Spontaneous shifts between these centrally generated motor activities completely changed the SR1-evoked reflex responses. 2. During spontaneous centrally initiated flexion activity, tonic SR1 neuron discharge elicited an assistance response that included excitation of a medium-sized flexor excitor (f3) and the peripheral extensor inhibitor (e5), and inhibition of at least one extensor excitor. Neither the other flexor excitors nor the peripheral flexor inhibitor (f5) were affected by SR1 excitation. 3. During spontaneous centrally initiated extension activity, SR1 activity elicited a response that included excitation of the extensor excitors and the flexor peripheral inhibitor (f5) only, f3 and e5 spontaneous activities were unchanged. This response was a resistance reflex, since SR1 discharge normally resulted from an imposed abdominal flexion. 4. The SR1-initiated control of postural motor activity in lobster differs from previously published results in the crayfish Procambarus clarkii.

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.

A muscle receptor organ in the scorpion postabdomen

1972 ◽  
Vol 81 (2) ◽  
pp. 133-146 ◽  
Author(s):  
Robert F. Bowerman
Keyword(s):  
Muscle Receptor ◽  
Receptor Organ

Sensory feedback and central afferent interaction in the muscle receptor organ of the crab, Carcinus maenas

1996 ◽  
Vol 76 (2) ◽  
pp. 788-798 ◽  
Author(s):  
M. Wildman ◽  
A. Cannone
Keyword(s):  
Action Potentials ◽  
Sensory Feedback ◽  
Carcinus Maenas ◽  
Small Diameter ◽  
Sensory Response ◽  
Fiber Direction ◽  
Single Action ◽  
Muscle Receptor ◽  
Leg Muscles ◽  
Receptor Organ

1. An interaction exists between two proprioceptive afferent neurons innervating the thoracic-coxal muscle receptor organ (TCMRO) of the crab, Carcinus maenas. Intracellular recordings were made from the extraganglionic regions of the afferents in order to characterize this interaction and its effects on sensory feedback. 2. A current-induced depolarization of the nonspiking T fiber of the TCMRO results in a depolarization of the P fiber, a small-diameter (7 microns) neuron innervating the same receptor. This interaction is graded in amplitude, and may result in a single action potential being superimposed on the graded response of the P fiber. A hyperpolarization of the T fiber has a smaller effect on the P fiber than a depolarization of similar amplitude. The interaction is rectified in a T- to P-fiber direction, and has a minimum central delay of approximately 3.6 ms. 3. The site of the interaction between the afferents is situated centrally, within the thoracic ganglion. Action potentials evoked in the P fiber by a T-fiber depolarization propagate actively and antidromically to the periphery. 4. Central modulation of the interaction occurs, because the amplitude of a T-fiber-induced depolarization is reduced in the P fiber during centrally generated spontaneous bursts of activity in the motoneurons of basal leg muscles. 5. Because of the interaction between T and P fibers, action potentials recorded from the peripheral portion of the P fiber during receptor stretch may be either orthodromic, resulting directly from the effects of the stretch on the sensory endings of the P fiber, or antidromic, resulting from the central input from the T fiber. 6. The T- to P-fiber interaction may serve to extend the dynamic sensitivity range of the P fiber, in particular by amplifying its sensory response at short receptor lengths and low velocities of stretch.

Synaptic connections between nonspiking afferent neurons and motor neurons underlying phase-dependent reflexes in crayfish

1992 ◽  
Vol 67 (3) ◽  
pp. 664-679 ◽  
Author(s):  
P. Skorupski
Keyword(s):  
Motor Neurons ◽  
Active State ◽  
Synaptic Delay ◽  
Dependent Manner ◽  
Synaptic Connections ◽  
Afferent Neurons ◽  
Motor Patterns ◽  
Dependent Inhibition ◽  
Receptor Organ ◽  
Group 1

1. This paper analyzes the synaptic connections made by nonspiking afferent neurons of the thoracocoxal muscle receptor organ (TCMRO) with basal limb motor neurons in the crayfish. The T fiber, a dynamically sensitive afferent, monosynaptically excites promotor motor neurons. Evidence suggests that both tonic graded chemical transmission and electrical synaptic transmission may be involved, depending on the motor neuron under consideration. 2. In preparations in the active state (spontaneously producing reciprocal motor patterns), the T fiber also inhibits promotor motor neurons in a phase-dependent manner. This inhibitory pathway is probably indirect, because it involves additional synaptic delay. 3. The statically sensitive S fiber also excites promotor motor neurons, but phase-dependent inhibition of promotor motor neurons by the S fiber was not seen. 4. The T fiber excites a subclass of remotor motor neurons (group 1) by a combination of direct chemical input and electrical input. This connection underlies the positive feedback reflex that excites these remotor motor neurons, in a phase-dependent manner, on stretch of the TCMRO during the active state. In inactive preparations, this connection remains subthreshold. 5. Central synaptic outputs of group 1 remotor motor neurons can also inhibit promotor motor neurons. This pathway may contribute to the phase-dependent reflex inhibition of promotor motor neurons that occurs in the active state.

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