Faculty Opinions recommendation of Embryonic assembly of a central pattern generator without sensory input.

Small Proportion ◽

Nerve Cord ◽

Sensory Input ◽

Pattern Generator ◽

Nerve Cords

Please send reprint requests and enquiries to this author A machine was used to impose controlled movements, closely resembling natural movements, on some of the swimmerets of crayfish with their ventral nerve cords cut between thorax and abdomen. The rhythm of the unrestrained swimmerets could be entrained to the imposed frequency. Full entrainment occurred most readily when three or four swimmerets were controlled and was uncommon with two. When one was controlled, only partial entrainment was seen. A small proportion of preparations could not be entrained irrespective of the number of swimmerets controlled. Entrainment of the neural rhythm also occurred when movement was imposed on one or more swimmerets attached to an otherwise isolated nerve cord. This is the first demonstration that sensory input affects the periodicity of the swimmeret rhythm. In the light of this result, the hypothesis that swimmeret rhythm is largely controlled by a central pattern generator should be viewed with caution. It now appears that there is also an influential sensory component responsible for stabilizing and adjusting the timing of the swimmeret rhythm.

Gating of Afferent Input by a Central Pattern Generator

10.1152/jn.1999.81.2.950 ◽

1999 ◽

Vol 81 (2) ◽

pp. 950-953 ◽

Cited By ~ 8

Author(s):

Ralph A. DiCaprio

Keyword(s):

Sensory Input ◽

Motor Pattern ◽

Pattern Generator ◽

Afferent Input ◽

Inhibitory Input ◽

Cycle Period ◽

Intracellular Recordings ◽

Afferent Fibers ◽

Sufficient Magnitude

Gating of afferent input by a central pattern generator. Intracellular recordings from the sole proprioceptor (the oval organ) in the crab ventilatory system show that the nonspiking afferent fibers from this organ receive a cyclic hyperpolarizing inhibition in phase with the ventilatory motor pattern. Although depolarizing and hyperpolarizing current pulses injected into a single afferent will reset the ventilatory motor pattern, the inhibitory input is of sufficient magnitude to block afferent input to the ventilatory central pattern generator (CPG) for ∼50% of the cycle period. It is proposed that this inhibitory input serves to gate sensory input to the ventilatory CPG to provide an unambiguous input to the ventilatory CPG.

Rhythmic activity of feline dorsal and ventral spinocerebellar tract neurons during fictive motor actions

10.1152/jn.00649.2012 ◽

2013 ◽

Vol 109 (2) ◽

pp. 375-388 ◽

Cited By ~ 20

Author(s):

Brent Fedirchuk ◽

Katinka Stecina ◽

Kasper Kyhl Kristensen ◽

Mengliang Zhang ◽

Claire F. Meehan ◽

...

Keyword(s):

Sensory Input ◽

Rhythmic Activity ◽

Pattern Generator ◽

Afferent Feedback ◽

Fictive Locomotion ◽

Decerebrate Cat ◽

Motor Behaviors ◽

Spinocerebellar Tract ◽

Motor Actions

Neurons of the dorsal spinocerebellar tracts (DSCT) have been described to be rhythmically active during walking on a treadmill in decerebrate cats, but this activity ceased following deafferentation of the hindlimb. This observation supported the hypothesis that DSCT neurons primarily relay the activity of hindlimb afferents during locomotion, but lack input from the spinal central pattern generator. The ventral spinocerebellar tract (VSCT) neurons, on the other hand, were found to be active during actual locomotion (on a treadmill) even after deafferentation, as well as during fictive locomotion (without phasic afferent feedback). In this study, we compared the activity of DSCT and VSCT neurons during fictive rhythmic motor behaviors. We used decerebrate cat preparations in which fictive motor tasks can be evoked while the animal is paralyzed and there is no rhythmic sensory input from hindlimb nerves. Spinocerebellar tract cells with cell bodies located in the lumbar segments were identified by electrophysiological techniques and examined by extra- and intracellular microelectrode recordings. During fictive locomotion, 57/81 DSCT and 30/30 VSCT neurons showed phasic, cycle-related activity. During fictive scratch, 19/29 DSCT neurons showed activity related to the scratch cycle. We provide evidence for the first time that locomotor and scratch drive potentials are present not only in VSCT, but also in the majority of DSCT neurons. These results demonstrate that both spinocerebellar tracts receive input from the central pattern generator circuitry, often sufficient to elicit firing in the absence of sensory input.

Multiple mechanisms for peripheral activation of the peptide-containing radula mechanoafferent neurons B21 and B22 of Aplysia

10.1152/jn.1996.76.2.1344 ◽

1996 ◽

Vol 76 (2) ◽

pp. 1344-1351 ◽

Cited By ~ 14

Author(s):

E. C. Cropper ◽

C. G. Evans ◽

S. C. Rosen

Keyword(s):

Sensory Neurons ◽

Sensory Input ◽

Pattern Generator ◽

Contractile Properties ◽

Mechanical Stimuli ◽

Buccal Ganglion ◽

Motor Programs ◽

Peripheral Activation ◽

Stimulation Of

1. Recently a cluster of sensory neurons (peptidergic radula mechanoafferents) has been identified in the buccal ganglion of Aplysia that is likely to play an important role in influencing the activity of feeding motor programs. All of the neurons of this cluster, which includes the identified cells B21 and B22, send axons via the radula nerve to a layer of tissue that lies under the chitinous radula (the subradula tissue). 2. We show that the subradula tissue has contractile properties. In the absence of the CNS, contractions of the subradula tissue are elicited if the subradula tissue is stretched. Alternatively, contractions are elicited when extracellular suction electrodes are used to stimulate buccal nerve 3 or the radula nerve. 3. Previous studies have shown that neurons of the B21/B22 cluster respond to peripherally applied mechanical stimuli. We show that these neurons are also activated when the subradula tissue contracts. Axon spikes (A spikes) can be intracellularly recorded from radula mechanoafferent neurons when contractions of the subradula tissue are elicited either by stretch or by extracellular stimulation of buccal nerve 3. 4. Mechanical stimuli that are subthreshold when applied alone elicit A spikes if they are applied while the subradula tissue is contracting. We postulate that this type of interaction may play an important role in gating sensory input to the feeding central pattern generator.

Embryonic assembly of a central pattern generator without sensory input

Nature ◽

10.1038/416174a ◽

2002 ◽

Vol 416 (6877) ◽

pp. 174-178 ◽

Cited By ~ 112

Author(s):

Maximiliano L. Suster ◽

Michael Bate

Keyword(s):

Sensory Input ◽

Pattern Generator

Defense reaction in the pond snail Planorbis corneus. II. Central pattern generator

10.1152/jn.1994.71.3.891 ◽

1994 ◽

Vol 71 (3) ◽

pp. 891-897 ◽

Cited By ~ 4

Author(s):

Y. I. Arshavsky ◽

T. G. Deliagina ◽

I. L. Okshtein ◽

G. N. Orlovsky ◽

Y. V. Panchin ◽

...

Keyword(s):

Motor Neurons ◽

Sensory Input ◽

Pattern Generator ◽

Excitatory Input ◽

Whole Body ◽

Pond Snail ◽

Defense Reaction ◽

Initial Stimulus ◽

Planorbis Corneus

1. In the isolated CNS of the pond snail Planorbis corneus, spontaneous bursts of activity in the motor neurons (MNs) supplying the columellar muscle were occasionally observed. The biphasic pattern of this activity, with a shorter (3-5 s) initial burst and longer (20-40 s) subsequent burst, was similar to that of the motor output during the general ("whole-body") defense reaction. In preparations consisting of the CNS isolated with the columellar muscle or with the lung, spontaneous biphasic contractions of the muscle as well as openings of the pneumostome with a temporal pattern characteristic of the defense reaction were observed. These findings demonstrated that the efferent pattern of the defense reaction in the snail is, to a large extent, produced by a special neuronal mechanism (the central pattern generator, CPG) triggered by the sensory input, rather than generated by ongoing processing of sensory input. The CPG consists of two components responsible for generation of two phases of the defense reaction. A characteristic feature of the CPG is that the magnitude of its response depends in a graded fashion on the strength of the initial stimulus. 2. In the pleural ganglia there are at least two electrically connected interneurons (DRN1s) that play an important role in generation of the first phase of the defense reaction. Processes of the DRN1s form a ring passing through all (except pedal and buccal) ganglia. The DRN1s received an excitatory input when a peripheral nerve was stimulated. They generated action potentials of long (0.2-2 s) duration. The DRN1 from the right ganglion was studied in more detail.(ABSTRACT TRUNCATED AT 250 WORDS)