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. Author manuscript; available in PMC: 2015 Mar 1.
Published in final edited form as: Psychopharmacology (Berl). 2013 Nov 7;231(5):909–918. doi: 10.1007/s00213-013-3309-0

Figure 3. Fifty-kHz ultrasonic vocalizations increase following cocaine administration (load-up) before subsequently decaying.

Figure 3

The average number of ultrasonic vocalizations (USVs; mean ± SEM) is shown as a function of the number of infusions earned. Twenty-two kHz USVs were highest prior to cocaine SA and decayed following the first infusion of cocaine. Fifty-kHz USVs rapidly increased following the first infusion but decayed as SA continued. During the pre-drug period (i.e., ‘0’ infusions earned) individual subjects emitted exclusively 22- or 50-kHz USVs during 85% of observations. The remaining observations were characterized by baseline rates of USV emission or a mix of 22- and 50-kHz USVs with one call category always predominating (Mean=15-fold difference). Nine of eleven subjects exhibited increases in 50-kHz USVs following the first infusion of cocaine while the remaining two subjects exhibited primarily decreases in 22-kHz USVs over the same period. +: p < 0.10, *: p <0.05 when compared to the 22-kHz range. α: p< 0.05 when compared within frequency to baseline.