Neuronal control of leech behavior

Kristan, William B.; Calabrese, Ronald L.; Friesen, W. Otto

doi:10.1016/j.pneurobio.2005.09.004

Cited by 343 publications

(376 citation statements)

References 306 publications

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“…(iv) Our HCO model consists of two neurons coupled by mutual inhibition. However, many biological CPGs contain more than two populations of neurons (Grillner 2003;Kiehn 2006;Kristan et al 2005;Varkonyi et al 2008;Smith et al 2007). A different analysis may be required to study the phase response properties of these CPGs.…”

Section: Discussionmentioning

confidence: 99%

Phase response properties of half-center oscillators

Zhang

Lewis

2013

J Comput Neurosci

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We examine the phase response properties of half-center oscillators (HCOs) that are modeled by a pair of Morris-Lecar-type neurons connected by strong fast inhibitory synapses. We find that the two basic mechanisms for half-center oscillations, "release" and "escape", give rise to strikingly different phase response curves (PRCs). Release-type HCOs are most sensitive to perturbations delivered to cells at times when they are about to transition from the active to the suppressed state, and PRCs are dominated by a large negative peak (phase delays) at corresponding phases. On the other hand, escape-type HCOs are most sensitive to perturbations delivered to cells at times when they are about to transition from the suppressed to the active state, and PRCs are dominated by a large positive peak (phase advances) at corresponding phases. By analyzing the phase space structure of Morris-Lecar-type HCO models with fast synaptic dynamics, we identify the dynamical mechanisms underlying the shapes of the PRCs. To demonstrate the significance of the different shapes of the PRCs for the release-type and escape-type HCOs, we link the shapes of the PRCs to the different frequency modulation properties of release-type

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Section: Discussionmentioning

confidence: 99%

Phase response properties of half-center oscillators

Zhang

Lewis

2013

J Comput Neurosci

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“…The leech heartbeat system has been described in detail (Kristan et al 2005; Thompson and Stent 1976a, 1976b, 1976c, so we provide a brief summary here. Blood flow in the leech circulatory system is accomplished by the rhythmic constriction of a pair of longitudinal vessels, the lateral heart tubes (referred to as "hearts").…”

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confidence: 99%

Contribution of motoneuron intrinsic properties to fictive motor pattern generation

Wright

Calabrese

2011

Journal of Neurophysiology

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Wright TM Jr, Calabrese RL. Contribution of motoneuron intrinsic properties to fictive motor pattern generation. J Neurophysiol 106: 538-553, 2011. First published May 11, 2011 doi:10.1152/jn.00101.2011.-Previously, we reported a canonical ensemble model of the heart motoneurons that underlie heartbeat in the medicinal leech. The model motoneurons contained a minimal set of electrical intrinsic properties and received a synaptic input pattern based on measurements performed in the living system. Although the model captured the synchronous and peristaltic motor patterns observed in the living system, it did not match quantitatively the motor output observed. Because the model motoneurons had minimal intrinsic electrical properties, the mismatch between model and living system suggests a role for additional intrinsic properties in generating the motor pattern. We used the dynamic clamp to test this hypothesis. We introduced the same segmental input pattern used in the model to motoneurons isolated pharmacologically from their endogenous input in the living system. We show that, although the segmental input pattern determines the segmental phasing differences observed in motoneurons, the intrinsic properties of the motoneurons play an important role in determining their phasing, particularly when receiving the synchronous input pattern. We then used trapezoidal input waveforms to show that the intrinsic properties present in the living system promote phase advances compared with our model motoneurons. Electrical coupling between heart motoneurons also plays a role in shaping motoneuron output by synchronizing the activity of the motoneurons within a segment. These experiments provide a direct assessment of how motoneuron intrinsic properties interact with their premotor pattern of synaptic drive to produce rhythmic output.

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“…from the same, identifiable neuron from one animal to the next and to link changes in a given neuron to a specific behavioral function (Burrell and Sahley, 2005;Kristan et al, 2005). Furthermore, the cellular and molecular properties between leech and vertebrates neurons are highly conserved (Burrell and Sahley, 2001), so discoveries about neural function in invertebrates are relevant to understanding processes in vertebrate neurons.…”

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confidence: 99%

Co-induction of long-term potentiation and long-term depression at a central synapse in the leech

Burrell

2008

Neurobiology of Learning and Memory

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Most studies of long-term potentiation (LTP) have focused on potentiation induced by the activation of postsynaptic NMDA receptors (NMDARs). However, it is now apparent that NMDAR-dependent signaling processes are not the only form of LTP operating in the brain (Malenka and Bear, 2004). Previously, we have observed that LTP in leech central synapses made by the touch mechanosensory neurons onto the S interneuron was NMDAR-independent (Burrell and Sahley, 2004). Here we examine the cellular mechanisms mediating T-to-S (T→S) LTP and find that its induction requires activation of metabotropic glutamate receptors (mGluRs), voltage-dependent Ca 2+ channels (VDCCs) and protein kinase C (PKC). Surprisingly, whenever LTP was pharmacologically inhibited, long-term depression (LTD) was observed at the tetanized synapse, indicating that LTP and LTD were activated at the same time in the same synaptic pathway. This co-induction of LTP and LTD likely plays an important role in activity-dependent regulation of synaptic transmission. Keywordsmetabotropic glutamate receptor; voltage-dependent Ca 2+ channel; protein kinase C; neuroplasticity; invertebrate NMDAR-dependent long-term potentiation (LTP) and long-term depression (LTD) are thought to be critical cellular substrates for mediating learning and memory because their initiation requires coincident activity in both the pre-and postsynaptic neurons (activity dependence) and the resulting changes are restricted to the co-activated synapses (synapse specificity). However, it is now clear that other molecules can perform coincidence-detection in place of NMDARs for both LTP and LTD (Malenka and Bear, 2004;Anwyl, 2006). This heterogeneity in cellular mechanisms mediating LTP and LTD, along with the structural complexity of the vertebrate brain, complicates efforts to determine the functional contribution of synaptic changes to learning-related changes in behavior. The medicinal leech (Hirudo medicinalis) has a number of properties that make it a useful model for studies of LTP and LTD. Most neurons in the leech CNS are large and easily visualized and there are far fewer neurons in the leech CNS (~400 neurons/ganglion with 21 body ganglia plus the head and tail ganglia )) compared to a mammalian brain. Therefore, it is possible to record

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Neuronal control of leech behavior

Cited by 343 publications

References 306 publications

Phase response properties of half-center oscillators

Phase response properties of half-center oscillators

Contribution of motoneuron intrinsic properties to fictive motor pattern generation

Co-induction of long-term potentiation and long-term depression at a central synapse in the leech

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