Synaptic plasticity is sensitive to the rate and the timing of presynaptic and postsynaptic action potentials. In experimental protocols inducing plasticity, the imposed spike trains are typically regular and the relative timing between every presynaptic and postsynaptic spike is fixed. This is at odds with firing patterns observed in the cortex of intact animals, where cells fire irregularly and the timing between presynaptic and postsynaptic spikes varies. To investigate synaptic changes elicited by in vivo-like firing, we used numerical simulations and mathematical analysis of synaptic plasticity models. We found that the influence of spike timing on plasticity is weaker than expected from regular stimulation protocols. Moreover, when neurons fire irregularly, synaptic changes induced by precise spike timing can be equivalently induced by a modest firing rate variation. Our findings bridge the gap between existing results on synaptic plasticity and plasticity occurring in vivo, and challenge the dominant role of spike timing in plasticity.

There has been considerable interest in a stimulus ("the dress") that yields starkly divergent subjective color percepts between observers. It has been proposed that individual differences in the subjective interpretation of this stimulus are due to the different assumptions that individuals make about how the dress was illuminated. In this study, we address this possible explanation empirically by reporting on data from ∼13,000 observers who were surveyed online. We show that assumptions about the illumination of the dress-i.e., whether the stimulus was illuminated by natural or artificial light or whether it was in a shadow-strongly affects the subjective interpretation of observers, compared to demographic factors, such as age or gender, which have a relatively smaller influence. We interpret these findings in a Bayesian framework by also showing that prior exposure to long- or short-wavelength lights due to circadian type shapes the subjective experience of the dress stimulus in theoretically expected ways.

In this issue of Neuron, Chowdhury and DeAngelis report that training monkeys to perform a fine depth discrimination abolishes the contribution of signals from area MT to the execution of a different, coarse depth discrimination. This result calls into question the principle of associating particular visual areas with particular visual functions, by showing that such associations are modifiable by experience.

How well do we remember popular music? To investigate how hit songs are recognized over time, we randomly selected number-one Billboard singles from the last 76 years and presented them to a large sample of mostly millennial participants. In response to hearing each song, participants were prompted to indicate whether they recognized it. Plotting the recognition proportion for each song as a function of the year during which it reached peak popularity resulted in three distinct phases in collective memory. The first phase is characterized by a steep linear drop-off in recognition for the music from this millennium; the second phase consists of a stable plateau during the 1960s to the 1990s; and the third phase, a further but more gradual drop-off during the 1940s and 1950s. More than half of recognition variability can be accounted for by self-selected exposure to each song as measured by its play count on Spotify. We conclude that collective memory for popular music is different from that of other historical phenomena.

No abstract