Indexed on: 25 Jan '17Published on: 25 Jan '17Published in: Alcoholism: Clinical and Experimental Research
Negative emotional status and adverse emotional events increase vulnerability to alcohol abuse. Ultrasonic vocalizations (USVs) emitted by rats are a well-established model of emotional status that can reflect positive or negative affective responses in real-time. Most USV studies assess counts, yet each USV is a multidimensional data point characterized by several acoustic characteristics that may provide insight into the neurocircuitry underlying emotional response.USVs emitted from selectively bred alcohol-naïve and alcohol-experienced alcohol-preferring and non-preferring rats (P and NP rats) were recorded during 4-hr sessions on alternating days over 4 weeks. Linear mixed modeling (LMM) and linear discriminant analysis (LDA) were applied to USV acoustic characteristics (e.g., frequency, duration, power and bandwidth) of negative (22-28 kHz) and positive (50-55 kHz) affect-related USVs.100% separation between alcohol-naïve P and NP rats was achieved through a linear combination (produced by LDA) of USV acoustic characteristics of 22-28 kHz USVs, whereas poor separation (36.5%) was observed for 50-55 kHz USVs. 22-28 kHz LDA separation was high (87%) between alcohol-experienced P and NP rats, but was poor for 50-55 kHz USVs (57.3%). USV mean frequency and duration were the highest weighted characteristics in both the naïve and experienced 22-28 kHz LDA representations suggesting that alcohol experience does not alter the representations. LMM analyses of 22-28 kHz USV acoustic characteristics matched the LDA results. Poor LDA separation was observed between alcohol-naïve and experienced P rats for both 22-28 and 50-55 KHz USVs.Advanced statistical analysis of negative affect-associated USV data predicts future behaviors of excessive alcohol drinking and alcohol avoidance in selectively bred rats. USV characteristics across rat lines reveal affect-related motivation to consume alcohol and may predict neural pathways mediating emotional response. Further characterization of these differences could delineate particular neurocircuitry and methods to ameliorate dysregulated emotional states often observed in human alcohol abusers. This article is protected by copyright. All rights reserved.