Taking advantage of behavioral changes during development and training to assess sensory coding mechanisms

Abstract

The relationship between behavioral and neural performance has been explored in adult animals, but rarely during the developmental period when perceptual abilities emerge. We used these naturally occurring changes in auditory perception to evaluate underlying encoding mechanisms. Performance of juvenile and adult gerbils on an amplitude modulation (AM) detection task was compared with response properties from auditory cortex of age-matched animals. When tested with an identical behavioral procedure, juveniles display poorer AM detection thresholds than adults. Two neurometric analyses indicate that the most sensitive juvenile and adult neurons have equivalent AM thresholds. However, a pooling neurometric revealed that adult cortex encodes smaller AM depths. By each measure, neural sensitivity was superior to psychometric thresholds. However, juvenile training improved adult behavioral thresholds, such that they verged on the best sensitivity of adult neurons. Thus, periods of training may allow an animal to use the encoded information already present in cortex.

Positive impacts of early auditory training on cortical processing at an older age

“…However, higher SOP, the accurate reception of target stimuli in the presence of confusable distractors, and the retained connectional integrity of forebrain systems, all of which were intensely engaged by our simple training task, provide key indices of the measured level of protection that is commonly attributed to this "reserve" (2,43,44). Our results, together with those of others (37)(38)(39)(40)(41), therefore indicate that cognitive reserve may be amplified at any age, that the functional and physical impacts of this amplification can be long enduring, and that with appropriate training dosing, brain health and function is likely sustainable, at a high level, across the lifespan.…”

“…For example, exposing rat pups to noise during the critical period can induce a disrupted tonotopicity and degraded response tuning in the inferior colliculus and in cortical field A1, which in turn results in deteriorated behavioral function in adulthood (36). On the other hand, a period of training in rodents on a specific auditory task (i.e., sound amplitude modulation detection) during development produces a positive effect on adult perception in an identical task (37,38). Studies in humans have also demonstrated a link between music training early in life and better auditory processing skills later in life, especially in challenging listening environments (39)(40)(41).…”

Altered Sensory Code Drives Juvenile-to-Adult Behavioral Maturation inCaenorhabditis elegans

“…Work in nonmodel mammalian systems has attempted to understand the role of developmental behavioral differences at the level of sensory encoding and perception (Sarro et al, 2011). In particular, juvenile gerbils ( Meriones unguiculatus ) exhibit neural sensitivity that is superior to their behavioral threshold, suggesting that the capacity for robust behavior exists but is not executed in immature animals (Sarro et al, 2011).…”

“…In particular, juvenile gerbils ( Meriones unguiculatus ) exhibit neural sensitivity that is superior to their behavioral threshold, suggesting that the capacity for robust behavior exists but is not executed in immature animals (Sarro et al, 2011). Here, we establish the nematode Caenorhabditis elegans as a genetically tractable model for understanding the mechanisms driving behavioral maturation during development.…”

A maximum-likelihood procedure for estimating psychometric functions: Thresholds, slopes, and lapses of attention

“…This could mean a very large number of trials would have to be collected to accurately estimate the psychometric function, despite the fact that these subjects often have only limited time available for the experiment. To provide a third example, for research focused on developmental aspects of the auditory system and the effects of learning, the time required to obtain an estimate of the psychometric function must be minimized to ensure the temporal resolution of the assessment (e.g., Rosen et al, 2010;Sarro et al, 2011).…”