Activity of crayfish abdominal-positioning interneurones during spontaneous and sensory-evoked movements (original) (raw)
Related papers
Abdominal positioning interneurons in crayfish: participation in behavioral acts
Journal of Comparative Physiology A, 1989
Intracellular recording, stimulation, and Lucifer dye injections were used to characterize abdominal positioning interneurons from the neuropile of the second through sixth abdominal ganglia of the crayfish, Procambarus clarhii. Motor outputs of these cells were recorded with extracellular electrodes placed on various flexion and extension roots along the nerve cord. In a n effort to assess the functional relationships between the postural interneurons in the abdomen and those known to exist in the circumesophageal connectives (CECs), a stimulus pulse train was delivered to each of the CECs while monitoring the intracellular responses of the impaled interneurons. Abdominal positioning interneurons were grouped into four general categories based on their responses to CEC stimulation: 1) those that projected their axons directly through the CECs; 2) those that were remotely activated to spiking; 3) those locally activated to produce EPSPs or IPSPs; and 4) those that were not affected by CEC stimulation.
The Journal of experimental zoology, 1984
Intracellular recording, stimulation, and Lucifer dye injections were used to characterize abdominal positioning interneurons from the neuropile of the second through sixth abdominal ganglia of the crayfish, Procambarus clarkii. Motor outputs of these cells were recorded with extracellular electrodes placed on various flexion and extension roots along the nerve cord. In an effort to assess the functional relationships between the postural interneurons in the abdomen and those known to exist in the circumesophageal connectives ( CECs ), a stimulus pulse train was delivered to each of the CECs while monitoring the intracellular responses of the impaled interneurons. Abdominal positioning interneurons were grouped into four general categories based on their responses to CEC stimulation: 1) those that projected their axons directly through the CECs ; 2) those that were remotely activated to spiking; 3) those locally activated to produce EPSPs or IPSPs; and 4) those that were not affecte...
Neural basis of a simple behavior: Abdominal positioning in crayfish
Microscopy Research and Technique, 2003
Crustaceans have been used extensively as models for studying the nervous system. Members of the Order Decapoda, particularly the larger species such as lobsters and crayfish, have large segmented abdomens that are positioned by tonic flexor and extensor muscles. Importantly, the innervation of these tonic muscles is known in some detail. Each abdominal segment in crayfish is innervated bilaterally by three sets of nerves. The anterior pair of nerves in each ganglion controls the swimmeret appendages and sensory supply. The middle pair of nerves innervates the tonic extensor muscles and the regional sensory supply. The superficial branch of the most posterior pair of nerves in each ganglion is exclusively motor and supplies the tonic flexor muscles of that segment. The extension and flexion motor nerves contain six motor neurons, each of which is different in axonal diameter and thus produces impulses of different amplitude. Motor programs controlling each muscle can be characterized by the identifiable motor neurons that are activated. Early work in this field discovered that specific central interneurons control the abdominal positioning motor neurons. These interneurons were first referred to as "command neurons" and later as "command elements." Stimulation of an appropriate command element causes a complex, widespread output involving dozens of motor neurons. The output can be patterned even though the stimulus to the command element is of constant interval. The command elements are identifiable cells. When a stimulus is repeated in a command element, from either the same individual or from different individuals, the output is substantially the same. This outcome depends upon several factors. First, the command elements are not only identifiable, but they make many synapses with other neurons, and the synapses are substantially invariant. There are separate flexion-producing and extension-producing command elements. Abdominal flexion-producing command elements excite other flexion elements and inhibit extensor command elements. The extension producing elements do the opposite. These interactions insure that interneurons of a particular class (flexion-or extension-producing) synaptically recruit perhaps twenty others of similar output, and that command elements promoting the opposing movements are inhibited. This strong reciprocity and the recruitment of similar command elements give a powerful motor program that appears to mimic behavior.
Interactions between the tonic and cyclic postural motor programs in the crayfish abdomen
Journal of Comparative Physiology A, 1988
** To whom offprint requests should be sent presumably may form the basis of switching from one behavior to the other. We conclude, therefore, that each behavioral subsystem relies upon its own unique set ofpremotor interneurons. Finally, those interneurons contributing to the cyclic motor pattern have not yet been identified.
Temporal and Spatial Spread of an Intersegmental Reflex in Crayfish
SUMMARY An intersegmental reflex initiated by flexing a crayfish leg at the mero- carpal joint was examined by recording reflex response latencies of cephalic, thoracic and abdominal muscles. The first response was an intrasegmental resistance reflex in the extensor muscle of the stimulated leg. Spread of the intersegmental reflex occurred in both cephalic and caudal directions. Activation of the cephalic appendages occurred first (antennal levators, with latencies of 14-18 ms) while the abdominal musculature was activated last (superficial extensors, with latencies of 51-62ms). Shift of the stimulus site from the second to the fifth leg resulted in shorter latencies of the fifth leg and abdominal muscle responses while the latency for second leg extensor muscle discharge increased. Low correlation coefficients between the response latencies of pairs of cephalic and abdominal muscles, and thoracic and abdominal muscles, in- dicate that reflex pathways which initiate the abdominal re...
Monosynaptic Interjoint Reflexes and their Central Modulation During Fictive Locomotion in Crayfish
European Journal of Neuroscience, 1991
An in vitro preparation of the crayfish nervous system has been utilized to study an interjoint reflex pathway and its variability during rhythmic locomotor activity. The coxo-basal chordotonal organ (CBCO) is a joint stretch receptor spanning the second joint of walking legs in crayfish, where it encodes joint movements and position. Mechanical stimulation (stretch and release) of the CBCO and electrical stimulation of the CBCO nerve elicits reflex responses in promotor and remotor motor neurons innervating muscles moving the basal thoracocoxal (TC) leg joint. Promotor and remotor motor neurons receive monosynaptic excitatory inputs from at least four CBCO afferents, including both stretch-and release-sensitive CBCO afferents. In a tonic preparation, in which there is no tendency to produce alternating bursts of activity in antagonistic motor neurons, the reflex responses were evoked during each cycle of imposed movement. However, when the preparation became rhythmic and produced bouts of fictive locomotion, the reflex responses were unstable and their gain was phasically modulated. Paired recordings indicate that such a modulation of the monosynaptic interjoint reflex could be due to both a phasic change in the excitability of the motor neurons and presynaptic inhibition that reduces the excitatory input from CBCO primary afferents.
Extensor motor neurons of the crayfish abdomen
Journal of Comparative Physiology ? A, 1975
The somata of five deep extensor motoneurons of the third abdominal ganglion of the crayfish (Procambarus clarkii) were located and identified. The positions of these somata within the ganglion and their distal distribution to muscles have been mapped and were constant. The soma of the extensor inhibitor was noted to touch the soma of the flexor inhibitor. Three of the excitatory neurons were clustered near their exit route. Sensory and cord routes of activation of the extensor motoneurons were also found and were constant from preparation to preparation. Sub-threshold recording showed that these motoneurons exhibited radically different types of post-synaptie response to stimuli at different sites in the nervous system. No interaction between extensor motoneurons or between the extensor and flexor motoneurons was observed.
The Journal of experimental zoology, 1993
Crayfish exhibit complex cyclical adjustments in abdominal posture during certain forms of backward walking. An isolated nerve cord preparation was used to investigate the properties of the interneurons which direct this alternation of abdominal flexion and extension. The command function for this cyclic postural behavior appears to be the domain of a distributed network of multiple pattern-initiating interneurons: each interneuron may be viewed as a command element within a command system. The cyclic pattern may be elicited by stimulation of small axon bundles pulled from the ventrolateral margins of any of the abdominal connectives. As few as one stimulus pulse to the axon bundle can elicit a single cycle of patterned output, although more pulses are generally necessary. This suggests some convergence or amplification step in the pattern-initiating interneurons. The amplification may be accomplished by several pattern-initiating interneurons that are coupled to one another and con...
Intersegmental coordination in the crayfish swimmeret system reconsidered
Journal of Experimental Zoology
Stein c71, '74) demonstrated that lesions in areas 78 and 81 of the nerve cord of the crayfish Procambarus affected intersegmental coordination. In these areas he found neurons which appeared to be local interneurons and whose discharge was correlated with motor discharge in the swimmeret roots. He suggested that these neurons might be responsible for intersegmental coordination and termed them coordinating fibres. We reexamined the same areas of the ventral nerve cord in the crayfish Cherax by recording extracellularly from small bundles of axons during rhythmic activity in the swimmeret motor nerves. All the units we located that exhibited correlated discharge appeared to be plurisegmental. Physiological examination revealed that such units may be sensory, motor, or interneurons. We confirmed this finding morphologically by staining some of the units intracellularly with cobalt. Deafferentation experiments and the effects of stimulating units showing correlated discharge suggest that all three types of neurons may be involved in intersegmental coordination. We conclude that the present coordinating fibre model should be abandoned.