Functional consequences of animal-to-animal variation in circuit parameters

Abstract

How different are the neuronal circuits for a given behavior across individual animals? To address this question, we measured multiple cellular and synaptic parameters within individual preparations to see how they correlate with circuit function, using neurons and synapses within the pyloric circuit of the stomatogastric ganglion (STG) of the crab Cancer borealis. There was considerable preparation-to-preparation variability in the strength of two identified synapses, in the amplitude of a modulator-evoked current, and in the expression of six ion channel genes. Nonetheless, across preparations we found strong correlations among these parameters and attributes of circuit performance. These data illustrate the importance of making multidimensional measurements from single preparations to understand how variability in circuit output is related to the variability of multiple circuit parameters.

Contribution of motoneuron intrinsic properties to fictive motor pattern generation

“…In the pyloric network of the stomatogastric system, for example, the onset of the LP motoneuron is correlated to the synaptic conductance of each of its inputs from the pacemaker kernel, the AB/PD complex (Goaillard et al 2009). We do not see such correlations between single inputs and output phase in our system (Norris et al 2011), suggesting that there may be a more complex interaction between elements of the premotor synaptic conductance pattern and the heart motoneuron intrinsic properties.…”

Single Synapse Information Coding in Intraburst Spike Patterns of Central Pattern Generator Motor Neurons

“…The pyloric CPG can present a vast repertoire of rhythms in a single animal and across different specimens due to intrinsic variability in cellular excitability machinery, synaptic strength, and baseline neuromodulator concentrations. All animals used in our experiments were collected from their natural habitat, so we may consider the variability of pyloric activity observed to be representative of the dynamical repertoire that would be found in the natural environment (Goaillard et al, 2009). Our results revealed an information flow phenomenon that is ubiquitous among different preparations and for different species, despite striking differences in pyloric period, number of spikes per burst, or phase relations between LP and PD across different animals.…”

“…Recent experimental and theoretical works have shown that circuits with different cellular and network properties can present similar activity regarding bursting period and phase, meaning that they must be functionally equivalent (Marder and Prinz, 2002;Goaillard et al, 2009;Grashow et al, 2010). It has been proposed that such a remarkable phenomenon can be part of intricate mechanisms responsible for homeostasis maintenance.…”

“…It is widely known that pyloric neurons can present similar behavior in different preparations despite variations of their intrinsic excitability properties (Marder and Prinz, 2002;Goaillard et al, 2009). Is it possible for pyloric neurons of different animals to share a common information coding mechanism?…”

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“…Thus, control and experimental cells could be compared in the same 84 animal. MNs expressing EKI were identified by co-expression of a red fluorescent 85 protein (RFP) tag attached to the promoter and a green fluorescent protein (GFP) tag 86 attached to the EKI construct [22]. 87 Figure 1.…”