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Neural circuits controlling behavior and autonomic functions in medicinal leeches.

Lamb DG, Calabrese RL - Neural Syst Circuits (2011)

Bottom Line: In the study of the neural circuits underlying behavior and autonomic functions, the stereotyped and accessible nervous system of medicinal leeches, Hirudo sp., has been particularly informative.In this review, we discuss some of the best understood of these movements and the circuits which underlie them, focusing on swimming, crawling and heartbeat.We also discuss the rudiments of decision-making: the selection between generally mutually exclusive behaviors at the neuronal level.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA. ronald.calabrese@emory.edu.

ABSTRACT
In the study of the neural circuits underlying behavior and autonomic functions, the stereotyped and accessible nervous system of medicinal leeches, Hirudo sp., has been particularly informative. These leeches express well-defined behaviors and autonomic movements which are amenable to investigation at the circuit and neuronal levels. In this review, we discuss some of the best understood of these movements and the circuits which underlie them, focusing on swimming, crawling and heartbeat. We also discuss the rudiments of decision-making: the selection between generally mutually exclusive behaviors at the neuronal level.

No MeSH data available.


Related in: MedlinePlus

(A1) Voltage-sensitive dye recording of dorsal and a ventral excitatory longitudinal motor neurons, as well as a nerve, on which dorsal excitatory motor neuron bursts are recorded, in midbody ganglion 15. (Data in Figure 1A were kindly provided by Kevin Briggman from experiments described in [30].) Initially, in phase oscillations of the dorsal longitudinal excitatory (DE) and ventral longitudinal excitatory (VE) motor neurons with a period of about 20 seconds indicate fictive crawling. At the end of the recording, fictive swimming behavior commences. (A2) Zoom of fictive swimming motor pattern from (A1): DE and VE motor neurons oscillate out of phase and with a period of about one second. (B) Dorsal posterior (DP) nerve recordings from multiple ganglia during crawling demonstrate the phase lag between ganglia from front to rear. Downward arrows and lines indicate the start of a motor neuron burst for a selected cycle of fictive crawling. (Data kindly provided by Karen Mesce and Joshua Puhl.) (C) Simplified circuit schematic of a segmental oscillator of the swimming CPG and its intersegmental connectivity: component neurons are broken down into three phase groups, 0, 0.33 and 0.67, with the inter- and intrasegmental connectivity indicated. Less important elements are omitted from the schematic, that is, cells VI-2 and VI-119. The anterior projections are replications of the intrasegmental connectivity, whereas the posterior projections differ. Inhibitory motor neurons DI-102 and DI-1 participate in and can strongly influence the pattern produced. Only cells 28 and 27 have strictly reciprocal connectivity. (Original artwork adapted from [12], Figure 10, and from [5], Figure 15.)
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Figure 1: (A1) Voltage-sensitive dye recording of dorsal and a ventral excitatory longitudinal motor neurons, as well as a nerve, on which dorsal excitatory motor neuron bursts are recorded, in midbody ganglion 15. (Data in Figure 1A were kindly provided by Kevin Briggman from experiments described in [30].) Initially, in phase oscillations of the dorsal longitudinal excitatory (DE) and ventral longitudinal excitatory (VE) motor neurons with a period of about 20 seconds indicate fictive crawling. At the end of the recording, fictive swimming behavior commences. (A2) Zoom of fictive swimming motor pattern from (A1): DE and VE motor neurons oscillate out of phase and with a period of about one second. (B) Dorsal posterior (DP) nerve recordings from multiple ganglia during crawling demonstrate the phase lag between ganglia from front to rear. Downward arrows and lines indicate the start of a motor neuron burst for a selected cycle of fictive crawling. (Data kindly provided by Karen Mesce and Joshua Puhl.) (C) Simplified circuit schematic of a segmental oscillator of the swimming CPG and its intersegmental connectivity: component neurons are broken down into three phase groups, 0, 0.33 and 0.67, with the inter- and intrasegmental connectivity indicated. Less important elements are omitted from the schematic, that is, cells VI-2 and VI-119. The anterior projections are replications of the intrasegmental connectivity, whereas the posterior projections differ. Inhibitory motor neurons DI-102 and DI-1 participate in and can strongly influence the pattern produced. Only cells 28 and 27 have strictly reciprocal connectivity. (Original artwork adapted from [12], Figure 10, and from [5], Figure 15.)

Mentions: Leeches swim with a dorsoventral, approximately sinusoidal, undulatory traveling wave with a wavelength of approximately one body length [12]. Swimming begins with undulations at the anterior of the leech that travel toward the posterior sucker. Upon initiation of swimming, dorsoventral flattener muscles contract and flatten the entire leech, which takes on a body form reminiscent of a ribbon with a flared posterior sucker paddle. Dorsal and ventral longitudinal muscles are primarily responsible for swimming undulations and are innervated by dorsal excitatory motor neurons (DE-3, DE-5, DE-18 and DE-107), dorsal inhibitory motor neurons (DI-1 and DI-102), ventral excitatory motor neurons (VE-4, VE-8 and VE-108) and ventral inhibitory motor neurons (VI-2, VI-7 and VI-119) [10,13-15]. Alternating contraction and relaxation of the dorsal and ventral muscles results in rhythmic bending of the body segments with a period of 0.3 to 1.0 second and a phase lag, or intersegmental delay normalized to period, of 0.044 to 0.1 second per segment, which generates the traveling wave that is leech swimming [10,16]. In response to various inputs, isolated or semi-intact preparations can exhibit fictive swimming, in which DE and VE motor neurons show alternating bursts of activity within a period range similar to that of swimming (Figure 1A2) and intersegmental coordination with front-to-rear phase lags.


Neural circuits controlling behavior and autonomic functions in medicinal leeches.

Lamb DG, Calabrese RL - Neural Syst Circuits (2011)

(A1) Voltage-sensitive dye recording of dorsal and a ventral excitatory longitudinal motor neurons, as well as a nerve, on which dorsal excitatory motor neuron bursts are recorded, in midbody ganglion 15. (Data in Figure 1A were kindly provided by Kevin Briggman from experiments described in [30].) Initially, in phase oscillations of the dorsal longitudinal excitatory (DE) and ventral longitudinal excitatory (VE) motor neurons with a period of about 20 seconds indicate fictive crawling. At the end of the recording, fictive swimming behavior commences. (A2) Zoom of fictive swimming motor pattern from (A1): DE and VE motor neurons oscillate out of phase and with a period of about one second. (B) Dorsal posterior (DP) nerve recordings from multiple ganglia during crawling demonstrate the phase lag between ganglia from front to rear. Downward arrows and lines indicate the start of a motor neuron burst for a selected cycle of fictive crawling. (Data kindly provided by Karen Mesce and Joshua Puhl.) (C) Simplified circuit schematic of a segmental oscillator of the swimming CPG and its intersegmental connectivity: component neurons are broken down into three phase groups, 0, 0.33 and 0.67, with the inter- and intrasegmental connectivity indicated. Less important elements are omitted from the schematic, that is, cells VI-2 and VI-119. The anterior projections are replications of the intrasegmental connectivity, whereas the posterior projections differ. Inhibitory motor neurons DI-102 and DI-1 participate in and can strongly influence the pattern produced. Only cells 28 and 27 have strictly reciprocal connectivity. (Original artwork adapted from [12], Figure 10, and from [5], Figure 15.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3278399&req=5

Figure 1: (A1) Voltage-sensitive dye recording of dorsal and a ventral excitatory longitudinal motor neurons, as well as a nerve, on which dorsal excitatory motor neuron bursts are recorded, in midbody ganglion 15. (Data in Figure 1A were kindly provided by Kevin Briggman from experiments described in [30].) Initially, in phase oscillations of the dorsal longitudinal excitatory (DE) and ventral longitudinal excitatory (VE) motor neurons with a period of about 20 seconds indicate fictive crawling. At the end of the recording, fictive swimming behavior commences. (A2) Zoom of fictive swimming motor pattern from (A1): DE and VE motor neurons oscillate out of phase and with a period of about one second. (B) Dorsal posterior (DP) nerve recordings from multiple ganglia during crawling demonstrate the phase lag between ganglia from front to rear. Downward arrows and lines indicate the start of a motor neuron burst for a selected cycle of fictive crawling. (Data kindly provided by Karen Mesce and Joshua Puhl.) (C) Simplified circuit schematic of a segmental oscillator of the swimming CPG and its intersegmental connectivity: component neurons are broken down into three phase groups, 0, 0.33 and 0.67, with the inter- and intrasegmental connectivity indicated. Less important elements are omitted from the schematic, that is, cells VI-2 and VI-119. The anterior projections are replications of the intrasegmental connectivity, whereas the posterior projections differ. Inhibitory motor neurons DI-102 and DI-1 participate in and can strongly influence the pattern produced. Only cells 28 and 27 have strictly reciprocal connectivity. (Original artwork adapted from [12], Figure 10, and from [5], Figure 15.)
Mentions: Leeches swim with a dorsoventral, approximately sinusoidal, undulatory traveling wave with a wavelength of approximately one body length [12]. Swimming begins with undulations at the anterior of the leech that travel toward the posterior sucker. Upon initiation of swimming, dorsoventral flattener muscles contract and flatten the entire leech, which takes on a body form reminiscent of a ribbon with a flared posterior sucker paddle. Dorsal and ventral longitudinal muscles are primarily responsible for swimming undulations and are innervated by dorsal excitatory motor neurons (DE-3, DE-5, DE-18 and DE-107), dorsal inhibitory motor neurons (DI-1 and DI-102), ventral excitatory motor neurons (VE-4, VE-8 and VE-108) and ventral inhibitory motor neurons (VI-2, VI-7 and VI-119) [10,13-15]. Alternating contraction and relaxation of the dorsal and ventral muscles results in rhythmic bending of the body segments with a period of 0.3 to 1.0 second and a phase lag, or intersegmental delay normalized to period, of 0.044 to 0.1 second per segment, which generates the traveling wave that is leech swimming [10,16]. In response to various inputs, isolated or semi-intact preparations can exhibit fictive swimming, in which DE and VE motor neurons show alternating bursts of activity within a period range similar to that of swimming (Figure 1A2) and intersegmental coordination with front-to-rear phase lags.

Bottom Line: In the study of the neural circuits underlying behavior and autonomic functions, the stereotyped and accessible nervous system of medicinal leeches, Hirudo sp., has been particularly informative.In this review, we discuss some of the best understood of these movements and the circuits which underlie them, focusing on swimming, crawling and heartbeat.We also discuss the rudiments of decision-making: the selection between generally mutually exclusive behaviors at the neuronal level.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA. ronald.calabrese@emory.edu.

ABSTRACT
In the study of the neural circuits underlying behavior and autonomic functions, the stereotyped and accessible nervous system of medicinal leeches, Hirudo sp., has been particularly informative. These leeches express well-defined behaviors and autonomic movements which are amenable to investigation at the circuit and neuronal levels. In this review, we discuss some of the best understood of these movements and the circuits which underlie them, focusing on swimming, crawling and heartbeat. We also discuss the rudiments of decision-making: the selection between generally mutually exclusive behaviors at the neuronal level.

No MeSH data available.


Related in: MedlinePlus