Academic literature on the topic 'Leech ganglion neurons'
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Journal articles on the topic "Leech ganglion neurons"
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Becker, T. S., G. Bothe, A. J. Berliner, and E. R. Macagno. "Identified central neurons convey a mitogenic signal from a peripheral target to the CNS." Development 122, no. 8 (August 1, 1996): 2331–37. http://dx.doi.org/10.1242/dev.122.8.2331.
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Regulation of central neurogenesis by a peripheral target has been previously demonstrated in the ventral nerve cord of the leech Hirudo medicinalis (Baptista, C. A., Gershon, T. R. and Macagno, E. R. (1990). Nature 346, 855–858) Specifically, innervation of the male genitalia by the fifth and sixth segmental ganglia (the sex ganglia) was shown to trigger the birth of several hundred central neurons (PIC neurons) in these ganglia. As reported here, removal of the target early during induction shows that PIC neurons can be independently induced in each side of a ganglion, indicating that the inductive signal is both highly localized and conveyed to each hemiganglion independently. Further, since recent observations (Becker, T., Berliner, A. J., Nitabach, M. N., Gan, W.-B. and Macagno, E. R. (1995). Development, 121, 359–369) had indicated that efferent projections are probably involved in this phenomenon, we individually ablated all possible candidates, which led to the identification of two central neurons that appear to play significant roles in conveying the inductive signal to the CNS. Ablation of a single ML neuron reduced cell proliferation in its own hemiganglion by nearly 50%, on the average. In contrast, proliferation on the opposite side of the ganglion increased by about 25%, suggesting the possibility of a compensatory response by the remaining contralateral ML neuron. Simultaneous ablation of both ML neurons in a sex ganglion caused similar reductions in cell proliferation in each hemiganglion. Deletion of a single AL neuron produced a weaker (7%) but nonetheless reproducible reduction. Ablation of the other nine central neurons that might have been involved in PIC neuron induction had no detectable effect. Both ML and AL neurons exhibit ipsilateral peripheral projections, and both arborize mostly in the hemiganglion where they reside. Thus, we conclude that peripheral regulation of central neurogenesis is mediated in the leech by inductive signals conveyed retrogradely to each hemiganglion by specific central neurons that innervate this target and the hemiganglion they affect.
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Kazakova, T. A., A. I. Yusipovich, and G. V. Maksimov. "Investigation of Changes in Membrane Potential and Rhythmic Activity of the Retzius Neuron upon Stimulation of the Sensory P-Neuron." Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no. 6 (93) (December 2020): 137–44. http://dx.doi.org/10.18698/1812-3368-2020-6-137-144.
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It was found that in "natural neural networks", ganglia of the nervous system of a leech, the frequency of rhythmic excitation (a series of nerve impulses, RE) of one neuron is modulated upon activation of other neurons. Changes in the electrophysiological characteristics of the leech Retzius cell in response to electrical stimulation of one of the sensory neurons (P-cells) were revealed. Registration of changes in the membrane potential of neurons, as well as electrical stimulation of the P-cell was carried out using microelectrodes introduced into the cells. It was found that during electrical stimulation, P-cells increase the frequency of spontaneous RE of Retzius cells, the membrane potential of P-cells increases, but Retzius cells do not change. With an increase in the duration of stimulation, the RE frequency increases in both the P-cell and the Retzius cell. It has been found that RE Retzius cells, upon stimulation of P-cells, arise against the background of RE of the Retzius cell. Thus, during RE of sensory neurons and synaptic transmission to the Retzius cell, RE frequency modulation occurs. According to the authors, changes in the frequency of spontaneous RE of the Retzius neuron in the "natural neural network" are associated not only with a change in the RE frequency during excitation along nerve fibers from skin receptors, but also with the transformation of RE both between cells of one ganglion and between cells in different ganglia leech nerve chain
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Szczupak, L., and W. B. Kristan. "Widespread mechanosensory activation of the serotonergic system of the medicinal leech." Journal of Neurophysiology 74, no. 6 (December 1, 1995): 2614–24. http://dx.doi.org/10.1152/jn.1995.74.6.2614.
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The serotonergic system of the medicinal leech comprises a small number of iterated, identified neurons, of which the Retzius (Rz) neurons are major components. Activity in pressure mechanosensory (P) cells sufficient to elicit locomotory and defensive behaviors also excites Rz neurons. We characterized the interactions between P and Rz neurons within the ganglion and at different distances along the nerve cord. 2. Within a ganglion 1) P cells excited both Rz neurons, electrically close to the site of electrical coupling between the Rz neurons; 2) each of the four P cells had similar effects on the Rz neurons; and 3) homologous contralateral P cells shared interneuronal pathways. These data show that P cells provide nearly identical bilateral information onto Rz neurons. 3. Along the nerve cord 1) every P cell excited Rz neurons in ganglia anterior and posterior to the site of stimulation; 2) the signal was carried the entire length of the nerve cord along interneuronal pathways with similar overall (but regionally different) conduction velocities in the two directions; 3) the amplitude of the Rz responses was smaller as the distance to the activated P cell increased; 4) the rate of change of the amplitude along the cord was larger when the signal traveled from front-to-back than in the opposite direction. 4. These data shows that mechanosensory input from any segment could excite Rz neurons along the cord, in proportion to the intensity of the stimulus.
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Pastor, J., B. Soria, and C. Belmonte. "Properties of the nociceptive neurons of the leech segmental ganglion." Journal of Neurophysiology 75, no. 6 (June 1, 1996): 2268–79. http://dx.doi.org/10.1152/jn.1996.75.6.2268.
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1. The electrical responses of nociceptive (N) lateral and N medial neurons of the leech segmental ganglion to mechanical, chemical, and thermal stimulation of the skin were studied in a superfused ganglion-body wall preparation. 2. Mechanical indentation of the skin > 10 mN evoked in both types of cells a sustained discharge of impulses; afterdischarge was often observed with suprathreshold stimulations. 3. Application to the cutaneous receptive area of 10-100 mM acetic acid or of NaCI crystals and solutions also elicited a firing response in N medial and N lateral cells. In contrast, capsaicin applied to the skin (3.3 x 10(-5) to 3.3 x 10(-2) M) excited N lateral but not N medial neurons. Likewise, impulse discharges were obtained when capsaicin was applied to the cell bodies of N lateral but not of N medial neurons. 4. In both types of N neurons, heating of the skin above 39 degrees C evoked a discharge of impulses whose frequency was roughly proportional to temperature values. 5. Application of repeated suprathreshold heating cycles at 10-min intervals enhanced the impulse frequency of the response (sensitization). Shorter time intervals between heating cycles depressed the response to heat. Sensitization could not be obtained by equivalent soma depolarizations obtained by intracellular current injection. 6. Impulse discharges evoked by irritant agents were also augmented by previous application of noxious heat. 7. N lateral neurons fired in response to low-pH solutions and capsaicin directly applied onto the ganglion. N medial neurons responded inconsistently to acid and were insensitive to capsaicin. Action potentials evoked in N lateral cells by capsaicin had a slow rise, a prominent hump, and a prolonged afterhyperpolarization. 8. It is concluded that N neurons of the leech segmental ganglion respond to different modalities of noxious stimuli applied to their peripheral receptive fields and develop sensitization after repeated noxious stimulation. These properties are typical of mammalian polymodal nociceptors; thus N neurons may be a simple model for analysis of membrane mechanisms associated with polymodality of nociceptive neurons.
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Burgin, AM, and L. Szczupak. "Basal acetylcholine release in leech ganglia depolarizes neurons through receptors with a nicotinic binding site." Journal of Experimental Biology 201, no. 12 (June 15, 1998): 1907–15. http://dx.doi.org/10.1242/jeb.201.12.1907.
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The response of Retzius neurons, the main neuronal source of serotonin in the leech nervous system, to cholinergic agonists has been extensively investigated. In this study, we analyzed the effects of inhibiting the acetylcholinesterase (AChE) activity in the leech midbody ganglion on the electrophysiological activity of the Retzius neurons. Bath application of neostigmine and physostigmine (0.1-100 &mgr;mol l-1) produced, after a delay, a strong depolarization of the Retzius neurons with a dose-dependent amplitude and latency. The amplitude of this depolarization increased as the extracellular level of Ca2+ increased and decreased as the extracellular level of Ca2+ decreased. The response to neostigmine and physostigmine was inhibited by curare (100 &mgr;mol l-1), nicotine (10 &mgr;mol l-1), atropine (100 &mgr;mol l-1) and strychnine (100 &mgr;mol l-1), but was not affected by mecamylamine (100 &mgr;mol l-1) or hexamethonium (100 &mgr;mol l-1). Superfusion with solutions containing 100 &mgr;mol l-1 strychnine or atropine produced a progressive hyperpolarization of the Retzius neurons, while superfusion with 100 &mgr;mol l-1 curare did not. The hyperpolarization induced by atropine was inhibited in the presence of curare. Other neurons in the ganglion showed distinctive responses to the AChE inhibitors that were coincident with their responses to cholinergic agonists. The results suggest the existence of a basal level of acetylcholine (ACh) release in the leech ganglion that is powerfully counteracted by endogenous AChE activity. Under control conditions, this basal release appears to be sufficient to generate an ACh tonus that regulates the membrane potential of Retzius neurons. Since these neurons can support a sustained firing rate, which is dependent on the membrane potential, the results presented in this report suggest that the basal ACh tonus regulates the output of these neuromodulatory serotonergic neurons.
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Opdyke, C. A., and R. L. Calabrese. "Outward currents in heart motor neurons of the medicinal leech." Journal of Neurophysiology 74, no. 6 (December 1, 1995): 2524–37. http://dx.doi.org/10.1152/jn.1995.74.6.2524.
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1. Outward currents were studied in isolation in heart motor neurons in the medicinal leech, using the single-electrode voltage-clamp technique. The currents were divided into four distinct types on the basis of their time and voltage characteristics and sensitivity to external Ca2+ concentration. 2. The four types were a fast transient current, IKA; a slow transient current. IK1; a noninactivating current, IK2, all measured in a bathing solution in which Co2+ was substituted for Ca2+; and a calcium-sensitive current. IK1Cal which was revealed in a bathing solution containing normal levels of Ca2+. 3. The outward currents in heart motor neurons studied in different ganglia possessed differences of quality. For example, heart motor neurons from ganglia 3 or 4 had significantly less IK2 and IK1 than neurons recorded from more posterior ganglia. Heart motor neurons from ganglion 3 often had little or no IK1. Soma input resistance, electrotonic length, and soma capacitance measured in heart motor neurons from both anterior and posterior ganglia exhibited no significant differences. 4. IKA started to activate near -45 mV with half-maximal activation at about -20 mV and was fully inactivated by 0 mV: IK1 started to activate near -45 mV with half-maximal activation at about -10 mV and was not fully inactivated by 0 mV; IK2 started to activate near -50 mV; IK1Cal started to activate near -35 mV. The time constant of removal of inactivation for IKA was 25 ms, measured at -80 mV, and that for IK1 was 380 ms, measured at -40 mV. 5. Tetraethylammonium acetate (TEA) allowed to diffuse from the inside of the recording microelectrode effectively blocked IKA, IK1, and IK2. Bath-applied TEA (25 mM) acted similarly but was less effective, particularly at blocking Ik2. Bath-applied 4-aminopyridine effectively blocked the transient currents IKA and IK1. A reversal potential of -65 mV was found for the outward currents, corresponding to a mix of IK1 and IK2.
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Szczupak, L., J. Edgar, ML Peralta, and WB Kristan. "Long-lasting depolarization of leech neurons mediated by receptors with a nicotinic binding site." Journal of Experimental Biology 201, no. 12 (June 15, 1998): 1895–906. http://dx.doi.org/10.1242/jeb.201.12.1895.
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The serotonergic Retzius neurons of the leech midbody ganglia respond in a complex manner to pressure pulses of acetylcholine (ACh) applied onto their soma with a fast depolarization followed by a slower hyperpolarization and an additional delayed long-lasting depolarization. The delayed depolarization is the subject of the present study. The delayed depolarization could be elicited by long (>1 s) ACh pressure pulses or by short pulses (10 ms) of carbachol, nicotine and DMPP, but not by muscarinic agonists. It was inhibited by bath application of nicotine (10-100 micromol l-1), strychnine (100 micromol l-1) and atropine (10-100 micromol l-1). Nicotinic antagonists that blocked the fast depolarization and the slow hyperpolarization (100 micromol l-1 mecamylamine and d-tubocurarine) did not affect the delayed depolarization induced by carbachol. Partial replacement of the extracellular Na+ by glucamine caused a decrease in the amplitude of the response and a shift of its reversal potential to more negative values. Carbachol pulses applied to Retzius neurons of the ganglia innervating the reproductive segments elicited delayed depolarizations of much smaller amplitude than the ones recorded in Retzius neurons from standard segments. The delayed depolarization could be elicited by the application of short agonist pulses onto different loci over the surface of the ganglion, at a distance from the soma. Isolated cultured Retzius neurons did not exhibit the delayed depolarization although they readily expressed the earlier phases of the complex cholinergic response. Carbachol pulses applied to the soma of other neurons in the leech ganglion produced a variety of specific responses.The results suggest that the delayed depolarization was produced by the activation of a cationic conductance mediated by receptors with a pharmacological profile similar to that of the <IMG src="/images/symbols/&agr ;.gif" WIDTH="9" HEIGHT= "12" ALIGN="BOTTOM" NATURALSIZEFLAG="3">9 nicotinic receptors and was not a byproduct of the early phases of the cholinergic response. The response seemed to be initiated in the extensive neuropilar processes of the Retzius cell, enabling a persistent excitatory signal.
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Kuwada, John Y. "Pioneering and pathfinding by an identified neuron in the embryonic leech." Development 86, no. 1 (April 1, 1985): 155–67. http://dx.doi.org/10.1242/dev.86.1.155.
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Numerous investigations of pathfinding by embryonic neurons, including many leech neurons, have demonstrated that pathfinding is precise. Neurons project the correct number of growth cones which grow to their target areas by making specific choices along the way. However, one leech mechanosensory neuron, the dorsal P (PD) neuron, is unusual in the sense that it initially projects an excessive number of growth cones. One of the growth cones will form the peripheral axon while the others are eliminated. This suggests that PD is one of the earliest neurons to project a peripheral axon, i.e., it may pioneer a peripheral nerve, and that it searches with its multiple growth cones for an external cue which can guide it to its target area. Examination of the early PD axon with light and electon microscopy reveals that it indeed is the first growth cone in its nerve and that it grows in contact with a large non-neuronal (DV) cell until it reaches its target area. The DV cell has a unique morphology and location: a large cell body with thin fiat processes extending from the edge of the ganglion to the target area of the PD. It is also present with its unique morphology prior to axonal outgrowth by the PD neuron. These features suggest that the DV cell may be an attractive substrate and/or axonal guidance cue for the PD peripheral axon and therefore for the entire peripheral nerve.
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Becker, T., A. J. Berliner, M. N. Nitabach, W. B. Gan, and E. R. Macagno. "Target-induced neurogenesis in the leech CNS involves efferent projections to the target." Development 121, no. 2 (February 1, 1995): 359–69. http://dx.doi.org/10.1242/dev.121.2.359.
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During a critical period in leech embryogenesis, the sex nerves that connect the 5th and 6th midbody ganglia (MG5 and MG6) to the primordium of the male sexual organ carry a spatially localized signal that induces the birth of several hundred neurons specific to these ganglia. We examined particular cellular elements (afferents, efferents, non-neuronal components) within these nerves as potential conveyors of the inductive signal. We show that axons of peripheral sensory neurons in the male genitalia travel along the sex nerves and into MG5 and MG6, but reach the CNS after the critical period has elapsed and cannot, therefore, be involved in the induction. Of the six sex nerves, four contain non-neuronal cells that span the entire distance between the male genitalia and the sex ganglia. However, when male genitalia were transplanted to ectopic locations close to MG6, induction occurred frequently but only in MG6, mediated by ectopic nerves that do not contain these cells. Thus, non-neuronal cells specific to the normal sex nerves are not necessary for induction. In addition, dye injections into the target during the critical period failed to reveal migrating cells in the sex nerves that could convey the inductive signal to the CNS. Finally, we show that 11 pairs of central neurons in each ganglion project to the male organ early during the critical period. In the adult, at least 3 additional pairs of neurons in MG6 also innervate this target. We conclude that the only components of the sex nerves that connect the sex ganglia to the target during the critical period that could be associated with induced central mitogenesis are the axons of central neurons that innervate the male genitalia.
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Schmidt, J., and J. W. Deitmer. "Photoinactivation of the giant neuropil glial cells in the leech Hirudo medicinalis: effects on neuronal activity and synaptic transmission." Journal of Neurophysiology 76, no. 5 (November 1, 1996): 2861–71. http://dx.doi.org/10.1152/jn.1996.76.5.2861.
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1. We studied the effects of photoinactivation of neuropil glial (NG) cells of the leech Hirudo medicinalis on neuronal activity and synaptic transmission. Each segmental ganglion contains two of these giant glial cells, which are electrically and dye coupled. 2. One of the two NG cells in an isolated segmental ganglion was filled with the dye Lucifer yellow (LY). Subsequent irradiation of the ganglion with laser light (440 nm) to photolyze LY caused irreversible depolarization of both NG cells. The NG cells that were filled with LY depolarized from -73 +/- 1.1 (SE) mV to -22 +/- 2.4 mV within 25 +/- 2.8 min of continuous irradiation (n = 22). The other NG cell, which was not directly filled with LY, depolarized with some delay. 3. Photoinactivation of the NG cells caused an irreversible depolarization of Retzius neurons and noxious (N) sensory cells by a mean of 14 mV (n = 36) and 9 mV (n = 24), respectively. In addition, the input resistance was reduced by 54% in Retzius cells and by 34% in N cells. Spikes could not be evoked in Retzius cells after the inactivation of the NG cells, either by intracellular current injection or by electrical nerve stimulation. Similarly, anterior pagoda neurons, annulus erector neurons, and the excitor neurons of the ventrolateral circular muscles became inexcitable. However, N cells, heart interneurons, and most of the heart motor neurons, touch cells, and pressure cells could still generate spontaneous or evoked action potentials. 4. Photoinactivation of the NG cells impaired the electrical connection between the two Retzius neurons. The electrical coupling was completely eliminated in six of eight cell pairs and reduced by 66% in two others. 5. Photoinactivation of the NG cells in the 3rd and 4th segmental ganglion caused a complete block of the chemical synapse between reciprocal inhibitory heart interneurons in these ganglia; the bursting rhythm either stopped or changed to a tonic activity, whereas inhibitory postsynaptic potentials could not be recorded in either heart interneuron anymore. 6. Laser irradiation alone had no effect on neuronal activity and synaptic transmission. Addition of glutathione (10 mM) and ascorbic acid (10 mM) to the saline to bind extracellular radicals that might be produced by the irradiation did not suppress the effects caused by photoinactivation of NG cells. 7. Elevation of bath K+ concentration to 12 mM, acidification of the saline to pH 5.5, and alkalinization to pH 8.5 for 6 min each did not mimick the effects on membrane properties of Retzius cells as produced by inactivation of NG cells. The results suggest some role of glial cells in the maintenance of neuronal activity and electrical and chemical synaptic transmission.
Dissertations / Theses on the topic "Leech ganglion neurons"
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Moshtagh, Khorasani Majid. "Spontaneous and evoked electrical activity of neurons in leech Hirudo medicinalis studied by a new generation of voltage sensitive dyes." Doctoral thesis, SISSA, 2013. http://hdl.handle.net/20.500.11767/4092.
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By using the newly developed voltage sensitive dye VF2.1.Cl invented by Miller and colleagues (Miller et al. 2012), I monitored simultaneously the spontaneous electrical activity of approximately 80 neurons in a leech ganglion, representing around 20% of the entire neuronal population. Neurons imaged on the ventral surface of the ganglion either fired spikes regularly at a rate of 1-5 Hz or fired sparse spikes irregularly. In contrast, neurons imaged on the dorsal surface, fired spikes in bursts involving several neurons. The overall degree of correlated electrical activity among leech neurons was limited in control conditions but increased in the presence of the neuromodulator serotonin. The spontaneous electrical activity in a leech ganglion is segregated in three main groups: neurons comprising Retzius cells, Anterior Pagoda , Leydig and Annulus Erector motoneurons firing almost periodically, a group of neurons firing sparsely and randomly, and a group of neurons firing bursts of spikes of varying durations. These three groups interact and influence each other only weakly.
I was able to obtain long optical recordings for several minutes. I studied, also, the evoked response of nervous system by stimulating mechanosensory neurons. This work paves the way for further studies of multicellular networks using the new voltage sensitive dye.
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Caulfield, Jason Patrick. "Preparation for nerve membrane potential readings of a leech, laboratory setup and dissection process." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/130.
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A well documented laboratory setup, leech preparation process, and bio-potential data recording process are needed. Repeatability and quality data recordings are essential and thus dictate the requirements of the laboratory setup and processes listed above. Advances in technology have both helped and hindered this development. While very precise equipment is required to record the low voltage bio-potentials, noisy electronic equipment and wires surrounding the work area provide high levels of interference. Proper laboratory setup and data recording processes, however, limit the unwanted interference. Quality data can only be recorded from a properly handled and prepared leech subject. Proper setup and procedures result in quality recordings which lend a clean signal for furthering the understanding of nerve functionality. The electrophysiology lab at California Polytechnic State University in San Luis Obispo is an example of a proven lab setup for high quality signal capture.
Book chapters on the topic "Leech ganglion neurons"
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Pentreath, Victor W. "Metabolic Interactions Between Neurons and Glial Cells in Leech and Snail Ganglia." In Neuron—Glia Interrelations During Phylogeny, 161–96. Totowa, NJ: Humana Press, 1995. http://dx.doi.org/10.1007/978-1-59259-468-9_7.
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Pentreath, V. W., A. J. Pennington, L. H. Seal, and K. Swift. "Modulation by Neuronal Signals of Energy Substrate in the Glial Cells of Leech Segmental Ganglia." In Glial-Neuronal Communication in Development and Regeneration, 211–29. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-71381-1_14.
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Calabrese, Ronald L. "The Heartbeat Neural Control System of the Leech." In Handbook of Brain Microcircuits, edited by Gordon M. Shepherd and Sten Grillner, 575–80. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190636111.003.0053.
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In medicinal leeches, heartbeat is a continuous, automatic function. Rhythmic constrictions of two muscular lateral vessels (the hearts) move blood through the closed circulatory system. The hearts are coordinated so that one beats in a rear-to-front progression (peristaltically), whereas the other one beats nearly synchronously along its length. The same coordination modes as in the hearts—peristaltic and synchronous—occur in the heart motor neurons: on one side, they are active in a rear-to-front progression, while on the other, they are active nearly synchronously. The rhythmic activity pattern of the heart motor neurons derives from the cyclic inhibition that they receive from the heartbeat central pattern generator (CPG). The core CPG comprises seven bilateral pairs of identified heart (HN) interneurons that occur in the first seven ganglia, HN(1)–HN(7).
Conference papers on the topic "Leech ganglion neurons"
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Romanenko, Sergii, Peter H. Siegel, Daniel A. Wagenaar, and Victor Pikov. "Comparison of the effects of millimeter wave irradiation, general bath heating, and localized heating on neuronal activity in the leech ganglion." In SPIE BiOS, edited by Gerald J. Wilmink and Bennett L. Ibey. SPIE, 2013. http://dx.doi.org/10.1117/12.2006504.
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