Developmental stress impairs performance on an association task in male and female songbirds, but impairs auditory learning in females only

Abstract

In songbirds, early-life environments critically shape song development. Many studies have demonstrated that developmental stress impairs song learning and the development of song-control regions of the brain in males. However, song has evolved through signaller-receiver networks and the effect stress has on the ability to receive auditory signals is equally important, especially for females who use song as an indicator of mate quality. Female song preferences have been the metric used to evaluate how developmental stress affects auditory learning, but preferences are shaped by many non-cognitive factors and preclude the evaluation of auditory learning abilities in males. To determine whether developmental stress specifically affects auditory learning in both sexes, we subjected juvenile European starlings, Sturnus vulgaris, to either an ad libitum or an unpredictable food supply treatment from 35 to 115 days of age. In adulthood, we assessed learning of both auditory and visual discrimination tasks. Females reared in the experimental group were slower than females in the control group to acquire a relative frequency auditory task, and slower than their male counterparts to acquire an absolute frequency auditory task. There was no difference in auditory performance between treatment groups for males. However, on the colour association task, birds from the experimental group committed more errors per trial than control birds. There was no correlation in performance across the cognitive tasks. Developmental stress did not affect all cognitive processes equally across the sexes. Our results suggest that the male auditory system may be more robust to developmental stress than that of females.

Early life conditions that impact song learning in male zebra finches also impact neural and behavioral responses to song in females

“…Our finding of elevated ZENKir in dNCM of females from larger broods could indicate that developmental stress dampens the relatively higher response to novel acoustic stimuli. Our data cannot directly address this hypothesis because of our experimental design, but similar studies by Schmidt and colleagues (2013a) and Farrell and colleagues (2015;2016) support this conclusion.…”

“…These results are consistent with the interpretation that females from different treatment groups memorized tutor song equally well and were equally good at referencing those memories. We cannot rule out the possibility that females from larger broods have a dampened perceptual sensitivity to song, as is suggested by other studies (Farrell et al, 2016), but the finding that females from large broods had lower overall response levels during operant trials suggests birds in this study had reduced motivation to respond to song. Given that our brood size manipulation had no impact on boldness per se, it is unlikely that such reduced response reflects a treatment effect on behavioral phenotype or "personality".…”

Task Differences and Prosociality; Investigating Pet Dogs’ Prosocial Preferences in a Token Choice Paradigm

“…What this difference between the two tasks in this condition does highlight however, is i) that dogs, and probably other animals, are sensitive to rather subtle methodological changes in prosociality studies and ii) the social facilitation control is an extremely important condition to include in order to disentangle any differences between test and non-social control conditions (see also [2]). Other than the current study and the previous bar-pull task, this control has only been used in one other PCT paradigm study to date and the authors also found that chimpanzees chose the prosocial option equally often when the partner was, and was not, able to access the food [8].…”

“…The most commonly employed experimental methodology for investigating these prosocial, or other-regarding, preferences is the prosocial choice test (PCT)- whereby individuals can typically choose between rewarding only themselves (selfish; 1/0) or rewarding themselves and their partners (prosocial; 1/1). These studies, however, have produced contradictory results, with findings seemingly being affected by the methodology, species and even specific individuals or dyads [2]. …”

Proactive prosociality in a cooperatively breeding corvid, the azure-winged magpie ( Cyanopica cyana )

“…[1]), and prosociality was subsequently considered a human hallmark. Prosociality, here defined as helping another individual at low or no cost to the self [1], has since been tested in a multitude of primates with sometimes positive, sometimes negative and sometimes mixed results per species (for a review, see [2]). One of the hypotheses that tries to explain the evolutionary reasons for this mixed pattern is the cooperative breeding hypothesis (CBH), originally developed based on the relatively high prosocial tendencies of cooperatively breeding common marmosets [3].…”