In vivo effects of temperature on the heart and pyloric rhythms in the crab, Cancer borealis

Abstract

The heart and pyloric rhythms of crustaceans have been studied separately and extensively over many years. Local and hormonal neuromodulation and sensory inputs into these central pattern generator circuits play a significant role in an animal's response to perturbations, but are usually lost or removed during in vitro studies. To examine simultaneously the in vivo motor output of the crustacean heart and pyloric rhythms, we used photoplethysmography. In the population measured (n=49), the heart rhythm frequency ranged from 0.3 to 2.3 Hz. The pyloric rhythm varied from 0.2 to 1.6 Hz. We observed a weak correlation between the frequencies of the heart and pyloric rhythms. During multiple hour-long recordings, many animals held at a controlled temperature showed strong inhibitory bouts in which the heart decreased in frequency or become quiescent and the pyloric rhythm decreased in frequency. We measured the simultaneous responses of the rhythms to temperature ramps by heating or cooling the saline bath while recording both the heart and pyloric muscle movements. Q10, critical temperature (temperature at which muscle function is compromised) and changes in frequency were calculated for each of the rhythms tested. The heart rhythm was more robust to high temperature than the pyloric rhythm.

Coupling between fast and slow oscillator circuits in Cancer borealis is temperature-compensated

“…Here we show that two oscillator circuits can maintain coordinated output across a range of physiologically relevant temperatures. The cardiac ganglion, another circuit in the crab, which governs heartbeat, is also temperature-sensitive across a range of physiological temperature, again with a Q 10 of ~2 ( Kushinsky et al, 2019 ). In the pyloric, gastric mill and cardiac circuits, rhythmicity is maintained up to a critical temperature, and this critical temperature approximates the upper range of native ambient temperatures ( Tang et al, 2010 ; Städele et al, 2015 ; Kushinsky et al, 2019 ).…”

“…The coordination of oscillatory circuits, often with distinct temporal features, is therefore key to circuit function and information processing. Because fluctuations in a circuit’s environment can impact function ( Fonseca and Correia, 2007 ; Tang et al, 2010 ; Haddad and Marder, 2018 ; Haley et al, 2018 ; Kushinsky et al, 2019 ; He et al, 2020 ), it is important to know how robust this coordination is to externally or internally generated perturbations.…”

Variable brain wiring through scalable and relative synapse formation inDrosophila

“…Many neuron-based processes are temperature-compensated at the level of development or function, e.g. the precision of circadian clocks ( 22 ) and other rhythmic circuits ( 23, 24 ). On the other hand, developmental temperature can change outcomes, for example sex-determination in reptiles ( 25, 26 ).…”

Synaptic Strengths Dominate Phasing of Motor Circuit: Intrinsic Conductances of Neuron Types Need Not Vary across Animals

“…CPG neuronal networks have provided excellent opportunities to study this question (Marder and Calabrese, 1996). Studies across animals focused on properties such as constancy of phase (Hooper, 1997; Bucher et al, 2005; Goaillard et al, 2009; Hamood et al, 2015), period regulation (Kushinsky et al, 2019), and morphologic variability (Otopalik et al, 2017) in the pyloric and cardiac motor patterns of the STG of crustaceans. Similar studies have focused on swimming motor pattern in the lamprey (Grillner, 1974) and on the crayfish swimmeret system (Smarandache et al, 2009).…”