Of Mice and Music

In 2008, researchers from the University of Texas studied MDMA-conditioned reward responses under the influence of auditory stimuli (Feduccia & Duvauchelle, 2008). In this study, the researchers administered MDMA, also known as the party drug ecstacy, to mice and measured the dopamine, serotonin and locomotor responses in order to determine what effects noise had on the effects of MDMA. Did the auditory stimulus increase neurotransmitters in the reward center of the brain? Was locomotor response affected?

In order to answer this question, they administered methylenedioxymethamphetamine HCL (MDMA) to 100 adult male Sprague-Dawley rats and then exposed them to 3 levels of the independent variable, which was noise. In the primary experiment, the control group was exposed to an environment free of external auditory stimulus. The second experimental group was treated to white noise, and yet a third group was exposed to music (The Very Best Euphoric House Breakdown; Telstar Records, UK). The researchers hypothesized that auditory stimulus present in environments paired with MDMA would influence behavioral and nuerochemical responses. The dependent variables measured were levels of dopamine and serotonin in the nucleus accumbens and the locomotor responses of the rats. In a secondary experiment, they enabled the rats to self administer MDMA or saline, and observed frequency of use under the 3 noise conditions.

After the test sessions, they found that the levels of dopamine and serotonin were increased after MDMA injections, but were significantly higher in animals exposed to music during the sessions. Interestingly, DA and 5-ht levels were also higher in subjects administered saline. Noted also was that only under conditions of music + MDMA did the rats show an increased locomotor response. The rats danced, in effect. They concluded that paired sensorial stimulation can engage the same systems activated during drug use and significantly increase the neurochemical and behavioral responses. This conclusion supported their hypothesis and revealed that assessment of human drug abuse potential is difficult if studies do not reflect the conditions of use in a sensory rich environment.

The only real problem I can see in this experiment is that it does not truly replicate but one aspect (auditory) of the atmosphere in which the human drug user is exposed to during use. The average user of this "party drug" is exposed to sensory stimulus that is highly visual and tactile in nature as well. If the true goal is to understand the impact of sensory stimulus and its increased potential for neurotoxicity, then further study of a true sensory rich environment is needed to better replicate realistic conditions.