TY - JOUR
T1 - Animal-to-animal variability in the phasing of the crustacean cardiac motor pattern
T2 - An experimental and computational analysis
AU - Williams, Alex H.
AU - Kwiatkowski, Molly A.
AU - Mortimer, Adam L.
AU - Marder, Eve
AU - Zeeman, Mary Lou
AU - Dickinson, Patsy S.
PY - 2013
Y1 - 2013
N2 - The cardiac ganglion (CG) of Homarus americanus is a central pattern generator that consists of two oscillatory groups of neurons: "small cells" (SCs) and "large cells" (LCs). We have shown that SCs and LCs begin their bursts nearly simultaneously but end their bursts at variable phases. This variability contrasts with many other central pattern generator systems in which phase is well maintained. To determine both the consequences of this variability and how CG phasing is controlled, we modeled the CG as a pair of Morris-Lecar oscillators coupled by electrical and excitatory synapses and constructed a database of 15,000 simulated networks using random parameter sets. These simulations, like our experimental results, displayed variable phase relationships, with the bursts beginning together but ending at variable phases. The model suggests that the variable phasing of the pattern has important implications for the functional role of the excitatory synapses. In networks in which the two oscillators had similar duty cycles, the excitatory coupling functioned to increase cycle frequency. In networks with disparate duty cycles, it functioned to decrease network frequency. Overall, we suggest that the phasing of the CG may vary without compromising appropriate motor output and that this variability may critically determine how the network behaves in response to manipulations.
AB - The cardiac ganglion (CG) of Homarus americanus is a central pattern generator that consists of two oscillatory groups of neurons: "small cells" (SCs) and "large cells" (LCs). We have shown that SCs and LCs begin their bursts nearly simultaneously but end their bursts at variable phases. This variability contrasts with many other central pattern generator systems in which phase is well maintained. To determine both the consequences of this variability and how CG phasing is controlled, we modeled the CG as a pair of Morris-Lecar oscillators coupled by electrical and excitatory synapses and constructed a database of 15,000 simulated networks using random parameter sets. These simulations, like our experimental results, displayed variable phase relationships, with the bursts beginning together but ending at variable phases. The model suggests that the variable phasing of the pattern has important implications for the functional role of the excitatory synapses. In networks in which the two oscillators had similar duty cycles, the excitatory coupling functioned to increase cycle frequency. In networks with disparate duty cycles, it functioned to decrease network frequency. Overall, we suggest that the phasing of the CG may vary without compromising appropriate motor output and that this variability may critically determine how the network behaves in response to manipulations.
KW - Central pattern generator
KW - Morris-Lecar model
KW - Neuronal oscillators
KW - Phase relationships
UR - http://www.scopus.com/inward/record.url?scp=84878620113&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84878620113&partnerID=8YFLogxK
U2 - 10.1152/jn.01010.2012
DO - 10.1152/jn.01010.2012
M3 - Article
C2 - 23446690
AN - SCOPUS:84878620113
SN - 0022-3077
VL - 109
SP - 2451
EP - 2465
JO - Journal of neurophysiology
JF - Journal of neurophysiology
IS - 10
ER -