Use-dependent facilitation of electrical transmission involves changes to postsynaptic K+ current.

Activity-dependent modulation of electrical transmission typically involves Ca2+ influx acting directly on gap junctions or initiating Ca2+-dependent pathways that in turn modulate coupling. We now describe short-term use-dependent facilitation of electrical transmission between bag cell neurons from the hermaphroditic snail, Aplysia californica, that is instead mediated by changes in postsynaptic responsiveness. Bag cell neurons secrete reproductive hormone during a synchronous afterdischarge of action potentials coordinated by electrical coupling. Here, recordings from pairs of coupled bag cell neurons in culture showed that nonjunctional currents influence electrical transmission in a dynamic manner. Under a dual whole cell voltage-clamp, the junctional current was linear and largely voltage-independent, while in current-clamp, the coupling coefficient was similar regardless of the extent of presynaptic hyperpolarization. Moreover, a train stimulus of action potential-like waveforms, in a voltage-clamped presynaptic neuron, elicited electrotonic potentials, in a current-clamped postsynaptic neuron, that facilitated over time when delivered at a frequency approximating the afterdischarge. Junctional current remained constant over the train stimulus, as did postsynaptic voltage-gated Ca2+ current. However, postsynaptic voltage-gated K+ current underwent cumulative inactivation, suggesting that K+ current run-down facilitates the electrotonic potential by boosting the response to successive junctional currents. Accordingly, preventing run-down by blocking postsynaptic K+ channels occluded facilitation. Finally, stimulation of bursts in coupled pairs resulted in synchronous firing, where active neurons could recruit silent partners through short-term use-dependent facilitation. Thus, potentiation of electrical transmission may promote synchrony in bag cell neurons and, by extension, reproductive function.NEW & NOTEWORTHY The understanding of how activity can facilitate electrical transmission is incomplete. We found that electrotonic potentials between electrically coupled neuroendocrine bag cell neurons facilitated in a use-dependent fashion. Rather than changes to the junctional current, facilitation was associated with cumulative inactivation of postsynaptic K+ current, presumably augmenting responsiveness. When made to burst, neurons synchronized their spiking, in part by use-dependent facilitation bringing quiescent cells to the threshold. Facilitation may foster en masse firing and neurosecretion.

Mind-Body Practices and Self-Enhancement: Direct Replications of Gebauer et al.'s (2018) Experiments 1 and 2.

Mind-body practices such as yoga and meditation are often believed to instill a "quiet ego," entailing less self-enhancement. In two experiments, however, Gebauer et al. (2018) demonstrated that mind-body practices may actually increase self-enhancement, particularly because such practices become self-central bases for self-esteem. We conducted preregistered replications of both of Gebauer et al.'s experiments. Experiment 1 was a field study of Canadian yoga students (N = 97), and Experiment 2 was a multiwave meditation intervention among Canadian university students (N = 300). Our results supported Gebauer et al.'s original conclusions that mind-body practices increase self-enhancement. Although the self-centrality effects were not clearly replicated in either experiment, we found evidence that measurement and sampling differences may explain this discrepancy. Moreover, an integrative data analysis of the original and the replication data strongly supported all of Gebauer et al.'s conclusions. In short, we provide new evidence against the ego-quieting perspective and in support of the self-centrality interpretation of mind-body practices.