Differential effects of two early life stress paradigms on cerebellar-dependent delay eyeblink conditioning

Alexandra B Moussa-Tooks,William P Hetrick,John T Green

doi:10.1016/j.ynstr.2020.100242

Abstract

Early life stress paradigms have become prominent in the animal literature to model atypical development. Currently, two models have prevailed within the literature: (1) limited bedding or nesting and (2) maternal separation or deprivation. Both models have produced aberrations spanning behavior and neural circuitry. Surprisingly, these two models have yet to be directly compared. The current study utilized delay eyeblink conditioning, an associative learning task with a well-defined cerebellar circuit, to compare the behavioral effects of standard limited bedding (postnatal day 2–9, n = 15) and maternal separation (60 min per day during postnatal day 2–14, n = 13) early life stress paradigms. Animals in all groups exhibited robust learning curves. Surprisingly, facilitated conditioning was observed in the maternal separation group. Rats that underwent limited bedding did not differ from the control or maternal separation groups on any conditioning measures. This study contributes to a clearer understanding of early life stress paradigms and the claims made about their mechanisms, which if better clarified can be properly leveraged to increase translational value.

Highlights

Atypical development of neural and psychological systems is a topic of great interest
A total of 5 rats were removed prior to data analysis: 3 rats had a noisy eyelid EMG, 1 rat had an attenuated response to the eyelid stimulation, and 1 rat lost its headcap
Limited bedding had no effect on acquisition (Figure 1)

Summary

Introduction

Atypical development of neural and psychological systems is a topic of great interest. One particular risk factor known to skew developmental trajectories is early life stress. Paradigms that model early life stress in animals to produce the associated developmental aberrations have become widely utilized in the psychological and neuroscience literatures. One such model is limited bedding, variations of which are referred to as limited nesting or scarcity. Another prominent model is maternal separation or maternal deprivation. Though both models have become widely used and characterized independently, we are not aware of any studies directly comparing these two paradigms

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