Prolonged maturation of auditory perception and learning in gerbils

Abstract

In humans, auditory perception reaches maturity over a broad age range, extending through adolescence. Despite this slow maturation, children are considered to be outstanding learners, suggesting that immature perceptual skills might actually be advantageous to improvement on an acoustic task as a result of training (perceptual learning). Previous non-human studies have not employed an identical task when comparing perceptual performance of young and mature subjects, making it difficult to assess learning. Here, we used an identical procedure on juvenile and adult gerbils to examine the perception of amplitude modulation (AM), a stimulus feature that is an important component of most natural sounds. On average, Adult animals could detect smaller fluctuations in amplitude (i.e. smaller modulation depths) than Juveniles, indicating immature perceptual skills in Juveniles. However, the population variance was much greater for Juveniles, a few animals displaying adult-like AM detection. To determine whether immature perceptual skills facilitated learning, we compared naïve performance on the AM detection task with the amount of improvement following additional training. The amount of improvement in Adults correlated with naïve performance: those with the poorest naïve performance improved the most. In contrast, the naïve performance of Juveniles did not predict the amount of learning. Those Juveniles with immature AM detection thresholds did not display greater learning than Adults. Furthermore, for several of the Juveniles with adult-like thresholds, AM detection deteriorated with repeated testing. Thus, immature perceptual skills in young animals were not associated with greater learning.

Learning, worsening, and generalization in response to auditory perceptual training during adolescence

“…In both cases, no more than half of the trained adolescents benefited from a training regimen that reliably yielded across-session learning in adults, the adolescents who did learn across sessions did so at a slower rate than did adults, and a subset of adolescents, including some who were 14 years of age or older, actually got worse at the trained condition across training sessions. These trends are remarkably similar to those recently reported for juvenile vs adult gerbils trained on auditory amplitude modulation detection (Sarro and Sanes, 2010). Further, regardless of their across-session performance, the adolescents in both human studies showed a greater magnitude of within-session worsening than did adults.…”

Developmental hearing loss impairs signal detection in noise: putative central mechanisms

“…Each day of testing used a range of sound levels that bracketed the previous day’s threshold (Sarro and Sanes, 2010). Animals were tested for 4–5 days with increasing difficulty in order to determine thresholds for detecting the signal in noise (signal-to-noise ratio, SNR, quantified as the signal in dB minus the noise in dB).…”

A Behavioral Framework to Guide Research on Central Auditory Development and Plasticity

“…In fact, measures of attention during performance on an auditory task can remain stable during development, even though perceptual performance improves. For example, measures of attention do not have the same developmental trajectory as performance on tasks such as AM detection, FM detection, or intensity discrimination (Dawes and Bishop 2008; Sarro and Sanes, 2010; Buss et al, 2009; Banai et al, 2011). Furthermore, the maturation rates for different auditory tasks are not correlated (Figure 1), as would be expected if a non-sensory factor (e.g., selective attention) had a uniform influence on performance (Jensen and Neff, 1993; Hartley et al, 2000; Werner and Boike, 2001; Wright and Zecker, 2004; Dawes and Bishop, 2008; Moore et al, 2011; Banai et al, 2011).…”