GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Control of locomotion in marine mollusc Clione limacina III. On the origin of locomotory rhythm (1985)
    Springer
    Experimental brain research 58 (1985), S. 273-284 
    Details
    ISSN: 1432-1106
    Keywords: Pteropodial mollusc ; Pedal ganglia ; Locomotion ; Central pattern generator ; Neuron polarization ; Tetrodotoxin ; Cobalt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Neurons from the isolated pedal ganglia of the marine mollusc Clione limacina were recorded from intracellularly during generation of the locomotory rhythm. Polarization of single type 7 or type 8 interneurons (which discharge in the D-and V-phases of a swim cycle, respectively) strongly affected activity of the rhythm generator. Injection of depolarizing and hyperpolarizing current usually resulted in shortening and lengthening of a swim cycle, respectively. A short pulse of hyperpolarizing current shifted the phase of the rhythmic generator. The same effect could be evoked by polarization of efferent neurons of types 2, 3 and 4 which are electrically coupled to interneurons. On the contrary, polarization of types 1, 6 and 10 efferent neurons, having no electrical connections with interneurons, did not affect the locomotory rhythm. 2. A number of observations indicate that type 7 and 8 interneurons constitute the main source of postsynaptic potentials that were observed in all the “rhythmic” neurons of the pedal ganglia. Type 7 interneurons excited the D-phase neurons and inhibited the V-phase neurons; type 8 interneurons produced opposite effects. 3. Tetrodotoxin eliminated spike generation in all efferent neurons of the pedal ganglia, while in interneurons spike generation persisted. After blocking the spike discharges in all the efferent neurons, type 7 and 8 interneurons were capable of generating alternating activity. One may conclude that these interneurons determine the main features of the swim pattern, i.e., the rhythmic alternating activity of two (D and V) populations of neurons. 4. Both type 7 and type 8 interneurons were capable of endogenous rhythmic discharges with a period like that in normal swimming. This was demonstrated in experiments in which one of the two populations of “rhythmic” neurons (D or V) was inhibited by means of strong electrical hyperpolarization, as well as in experiments in which interaction between the two populations, mediated by chemical synapses, was blocked by Co2+ ions. 5. Type 7 and 8 interneurons were capable of “rebound”, i.e. they had a tendency to discharge after termination of inhibition. 6. V-phase neurons exerted not only inhibitory but also excitatory action upon D-phase neurons, the excitatory action being longer than the inhibitory one. 7. The main experimental findings correspond well to the model of rhythm generator consisting of two half centres possessing endogenous rhythmic activity. The half-centres exert strong, short duration inhibitory and weak long duration excitatory actions upon one another. The behaviour of such a model is considered and compared with that of the locomotor generator of Clione.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235309
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Control of locomotion in marine mollusc Clione limacina (1986)
    Springer
    Experimental brain research 63 (1986), S. 106-112 
    Details
    ISSN: 1432-1106
    Keywords: Pteropodial mollusc ; Pedal ganglia ; Locomotion ; Interneurons and efferent neurons ; Endogenous activity ; Isolated cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the pteropodial mollusc Clione limacina, the rhythmic locomotor wing movements are controlled by the pedal ganglia. The locomotor rhythm is generated by two groups of interneurons (groups 7 and 8) which drive efferent neurons. In the present paper, the activity of isolated neurons, which were extracted from the pedal ganglia by means of an intracellular electrode, is described. The following results have been obtained: 1. Isolated type 7 and 8 interneurons preserved the capability for generation of prolonged (100–200 ms) action potentials. The frequency of these spontaneous discharges was usually within the limit of locomotor frequencies (0.5–5 Hz). By de- or hyperpolarizing a cell, one could usually cover the whole range of locomotor frequencies. This finding demonstrates that the locomotor rhythm is indeed determined by the endogenous rhythmic activity of type 7 and 8 interneurons. 2. Type 1 and 2 efferent neurons, before isolation, could generate single spikes as well as high-frequency bursts of spikes. These two modes of activity were also observed after isolating the cells. Thus, the bursting activity of type 1 and 2 neurons, demonstrated during locomotion, is determined by their own properties. Type 3 and 4 efferent neurons generated only repeated single spikes both before and after isolation. 3. The activity of the isolated axons of type 1 and 2 neurons did not differ meaningfully from the activity of the whole cells. Furthermore, in the isolated pedal commissure, we found units whose activity (rhythmically repeating prolonged action potentials) resembled the activity of type 7 and 8 interneurons. These units seemed to be the axons of type 7 and 8 interneurons. Thus, different parts of the cell membrane (soma and axons) have similar electric properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235652
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Control of locomotion in marine mollusc Clione limacina IV. Role of type 12 interneurons (1985)
    Springer
    Experimental brain research 58 (1985), S. 285-293 
    Details
    ISSN: 1432-1106
    Keywords: Pteropodial mollusc ; Pedal ganglia ; Locomotion ; Central pattern generator ; Plateau potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Type 12 interneurons in pedal ganglia of Clione limacina exerted a strong influence upon the locomotor generator during “intense” swimming. These neurons generated “plateau” potentials, i.e. their membrane potential had two stable states: the “upper” one when a neuron was depolarized, and the “down” one, separated by 30–40 mV. The interneurons could remain in each state for a long time. Short depolarizing and hyperpolarizing current pulses, as well as excitatory and inhibitory postsynaptic potentials, could transfer the interneurons from one state to another. 2. When the pedal ganglia generated the locomotory rhythm, type 12 neurons received an EPSP and passed to the “upper” state in the V2-phase of a locomotor cycle. They remained at this state until the beginning of the D1-phase when they received an IPSP and passed to the “down” state. The EPSP in type 12 neurons was produced by type 8d neurons, and the IPSP by type 7 neurons. 3. Type 12 neurons exerted inhibitory influences upon many neurons active in the V1 and V2 phases, and excitatory influences upon the D-phase interneurons (type 7). 4. The functional role of type 12 neurons was to limit the activity of neurons discharging in the V-phase of a locomotory cycle. In addition, they enhanced the excitation of the D-phase neurons and promoted, thus, the transition from the V-phase to the D-phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235310
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Control of locomotion in marine mollusc Clione limacina I. Efferent activity during actual and fictitious swimming (1985)
    Springer
    Experimental brain research 58 (1985), S. 255-262 
    Details
    ISSN: 1432-1106
    Keywords: Pteropodial mollusc ; Locomotion ; Pedal ganglion ; Central pattern generator ; Identified neurons ; Serotonin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1.The marine mollusc Clione limacina swims by making rhythmic movements (with a frequency of 1–5 Hz) of its two wings. Filming demonstrated that the wings perform oscillatory movements in the frontal plane of the animal. During both the upward and downward movements of the wing, its posterior edge lagged behind the anterior one, i.e. the wing plane was inclined in relation to the longitudinal axis of an animal. As a result of this inclination, the wing oscillations in the frontal plane produce a force directed forwards. 2.In restrained animals with the body cavity opened (a whole-animal preparation), the wing position, electrical activity in the wing nerve and activity of two identified efferent neurons (1A and 2A) were recorded during locomotory wing movements. There were two bursts of activity in the wing nerve during the locomotory cycle, the first one corresponding to the excitation of efferent neurons controlling the wing elevation, and the second one, to the excitation of efferent neurons controlling the lowering of the wing. Neurons 1A and 2A fired reciprocally at the beginning of the phase of elevating and lowering the wing, respectively. During excitation of one of the neurons, an IPSP appeared in its antagonist. 3. A pair of isolated pedal ganglia of Clione was capable of generating the locomotory rhythm (“fictitious swimming”). In fictitious swimming, as in actual swimming, there were two bursts of activity in the wing nerve per locomotory cycle, and the 1A and 2A neurons fired reciprocally. Homologous neurons from the left and right ganglia fired inphase. A single pedal ganglion was also capable of generating the locomotory rhythm. 4.Serotonin (10-5–10-6 M) increased the locomotor activity both in the whole-animal preparation and in the isolated pedal ganglia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235307
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Control of locomotion in marine mollusc Clione limacina II. Rhythmic neurons of pedal ganglia (1985)
    Springer
    Experimental brain research 58 (1985), S. 263-272 
    Details
    ISSN: 1432-1106
    Keywords: Pteropodial mollusc ; Locomotion ; Pedal ganglion ; Interneurons ; Efferent neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1.Activity from neurons in isolated pedal ganglia of Clione limacina was recorded intracellularly during generation of rhythmic swimming. To map the distribution of cells in a ganglion, one of two microelectrodes was used to monitor activity of the identified neuron (1A or 2A), while the second electrode was used to penetrate successively all the visible neurons within a definite area of the ganglion. In addition, pairs of neurons of various types were recorded in different combinations with each other. Intracellular staining of neurons was also performed. 2.Each ganglion contained about 400 neurons, of which about 60 neurons exhibited rhythmic activity related to a swim cycle. These rhythmic neurons were divided into 9 groups (types) according to axonal projections, electrical properties and the phase of activity in a swim cycle. Three types of interneurons and six types of efferent neurons were distinguished. 3.Type 7 and 8 interneurons generated only one spike of long (50–150 ms) duration per swim cycle. Type 7 interneurons discharged in the phase of the cycle that corresponded (in actual swimming) to the dorsal movement of wings (D-phase). Type 8 interneurons discharged in the opposite phase corresponding to the ventral movement of wings (V-phase). With excitation of type 7 interneurons, an IPSP appeared in the type 8 interneurons, and vice versa. Neuropilar branching of these neurons was observed in the ipsilateral ganglion. In addition, they sent an axon to the contralateral ganglion across the pedal commissure. 4.Efferent neurons (i.e. the cell sending axons into the wing nerve) generated spikes of 1–5 ms duration. Type 1 and 3 neurons were excited in the D-phase of a swim cycle and were inhibited in the V-phase. Type 2 and 4 neurons were excited in the V-phase and inhibited in the D-phase. Type 10 neurons received only an excitatory input in the V-phase, while type 6 neurons received only an inhibitory input in the D-phase. 5. Type 12 interneurons were non-spiking cells, they generated a stable depolarization (“plateau”) throughout most of the V-phase. 6. Neurons of the same type from one ganglion (except for type 6) were electrically coupled to each other. There were also electrical connections between most neurons firing in the same phase of the cycle, i.e. between types 3 and 7, as well as between types 2, 4 and 8. Type 7 interneurons from the left and right ganglia were electrically coupled, the same was true for type 8 interneurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235308
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Control of locomotion in marine mollusc Clione limacina (1989)
    Springer
    Experimental brain research 78 (1989), S. 398-406 
    Details
    ISSN: 1432-1106
    Keywords: Pteropod mollusc ; Locomotion ; Central pattern generator ; Interneurons ; Plateau potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In previous work carried out on the isolated pedal ganglia of the pteropod mollusc Clione limacina we described the activity of a neuronal element (type 12 neuron) and looked into its role in the locomotor rhythm generation (Arshavasky et al. 1985d). As we learned subsequently, the activity was recorded from the neuron axon passing in the pedal ganglia, while the neuron soma was located in the pleural ganglia and consequently was cut off in the course of pedal ganglia isolation. It thus became necessary to reinvestigate the properties of this neuron and its role in locomotory rhythm generation by using less reduced preparation of the central nervous system. The following results were obtained. (1) Each pleural ganglion contains only one neuron of this type, this cell is thus to be considered as the identified neuron. The neuron's axon reaches into the pedal ganglion via the pleuro-pedal connective. Then the axon divides into two branches terminating in the lateral regions of both pedal ganglia. The neurons 12 from the left and right pleural ganglia have no direct connections with one another; their synchronous operation in the locomotor cycle is determined by common inputs. (2) The electrical properties of an intact neuron 12 and one without a soma are about the same. In either case the neuron generates “plateau” potentials, i.e., it may persist for a long time in the depolarized state. Plateau potentials can be induced by a depolarizing current pulse or by an EPSP, and terminated by hyperpolarizing current or by an IPSP. The neuron input resistance drops about twofold during generation of the plateau potential. (3) Recording of the neuron 12 in the pleural ganglia showed that its activity during “fictive swimming” does not differ from that of somadeprived axon recorded in the isolated pedal ganglia. The neuron generates a plateau potential in the V-phase of the locomotor cycle (definitions for the phases of the cycle were given in Arshavsky et al. 1985b). This potential is triggered by an EPSP evoked by subgroup 8d pedal neurons. The plateau potential terminates in the D-phase under the influence of an IPSP evoked by group 7 neurons. The effects of the neuron 12 on other neuronal elements of the locomotor generator in pedal ganglia do not depend on the presence of the cell soma either. (4) The pedal ganglia locomotor generator sometimes generates an “anomalous rhythm” when normal cycles alternate with reduced ones in which the activity of some groups of neurons is inhibited. Simultaneous recording from two neurons 12 demonstrated that the alternating rhythm generation was caused by the anomalous behaviour of one of the neurons 12: the neuron persisted in the depolarized state for one cycle and a half and not for half a cycle, as during the normal operation of the locomotor generator.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228912
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Activity of propriospinal neurons in segments C3 and C4 during fictitious locomotion in cats (1985)
    Springer
    Neurophysiology 17 (1985), S. 226-231 
    Details
    ISSN: 1573-9007
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Activity of propriospinal neurons in segments C3 and C4 was recorded in immobilized decerebrate cats, whose spinal cord was divided at the lower thoracic level, during locomotor activity of neuronal mechanisms controlling the forelimbs (fictitious locomotion of the forelimbs). Neurons were identified according to antidromic responses to stimulation of the lateral column of the spinal cord at level C6. Antidromic responses also appeared in 70% of these neurons to stimulation of the medullary lateral reticular nucleus. During fictitious locomotion, i.e., in the absence of afferent signals from the limb receptors, rhythmic modulation of the discharge of most neurons was observed, correlating with activity of motoneurons. If the rostral region of the cervical enlargement of the spinal cord was cooled, causing generation of the locomotor rhythm to cease, rhythmic activity of propriospinal neurons in segments C3 and C4 also ceased. The main source of modulation of activity of propriospinal neurons in segments C3 and C4 is thus the central spinal mechanisms controlling activity of the forelimbs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01052458
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Regeneration of pedal ganglion neurons in the sea butterfly Clione limacina (1985)
    Springer
    Neurophysiology 17 (1985), S. 317-322 
    Details
    ISSN: 1573-9007
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the pedal ganglia ofClione limacina the growth of neurites is traced in motoneurons after transection of the wing nerve and in interneurons after transection of the pedal commissure. Neurons were stained intracellularly with Lucifer yellow. In the motoneurons the neurites growing from the transected end of the axon and from the neuron soma spread to all nerve trunks departing from the ipsi- and contralateral ganglia. For nerve transection in the intact mollusk, wing movements were restored 10 days after the operation. In the interneurons the growing neurites branched within the pedal ganglion or spread to the cerebral ganglia, but they never reached the periphery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01052341
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Neurite growth and formation of connections in pteropodial mollusk neurons in culture (1987)
    Springer
    Neurophysiology 19 (1987), S. 70-75 
    Details
    ISSN: 1573-9007
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neurons from the peripharyngeal nerve ring detached from the pteropodial molluskClione limacina were cultured in polylysine prepared in a 25% Leibovitz saltwater medium containing 2% embryonic calf serum. Neurite outgrowth was observed in a proportion of the neurons, reaching its peak rate during the first three days. Neurites grew up to 300 µm in length. Membrane potential of the neurons measured 40–60 mV. The latter generated either single action potentials or volleys of spikes. Neural connections between 70 pairs of cells with overlapping neurites were investigated on days 3–4. An electrical connection was discovered between cells in 20% of the pairs examined and, in 6%, stimulating one neuron of a pair produced an inhibitory postsynaptic potential in the other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01055998
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Neural control of heartbeat in the pteropod mollusk Clione limacina (1989)
    Springer
    Neurophysiology 21 (1989), S. 137-143 
    Details
    ISSN: 1573-9007
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The heart of the pteropod molluskClione limacina is innervated by the median nerve arising from the left abdominal ganglion. Five neurons sending axons to the heart have been identified in theClione central nervous system with retrograde cobalt or Lucifer yellow staining. Neuron H1 located in the left pedal ganglion produced an excitatory effect on heart beat. Stimulation of three neurons, H2–H4, situated in a compact group in the medial region of the left abdominal ganglion, led to inhibition of cardiac contraction, while H5, located in the caudal region of the left abdominal ganglion, did not affect heart beat. The activity of efferent cardiac neurons (ECN) was found to be related to the operation of the locomotor rhythm generator. Spontaneous or reflex depression of the latter was found to inhibit neuron H1 and activate units H2–H4. The behavior of these ECN accounts for the positive correlation between heart operation and locomotor activity inClione limacina.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01056971
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...