Effects of Mozart Sonata on the rats' learning and memory performance

The so-called "Mozart effect" indicated that a musical environment might improve the learning capacity and spatial intelligence. After 1 week adaptation and 1 week acquisition period 12 male rats were exposed once a day to a 8.5-min-long arrangement of Mozart Sonata for Two Pianos in D Major (K 448). The animals' spatial learning and memory ability was tested in an 8-arm radial maze. Week 1 (adaptation); all animals had a 10-minute training twice a day, adapting them to find feed pellets in the maze arm ends. Week 2 (acquisition of the task): with one training per day, the rats were first individually trained to learn the general cues of the task, that is, entering each one of the 8 arms only once in a given session, with no more than one error per session in 6 consecutive days. Acquisition errors consisted of revisiting an arm previously entered in the same session. The percent rate of correct responses was counted as (correct responses/acquisition errors) x 100, and was taken as performance indicator. Week 3 and 5 (short-term working memory test): the rats (all 12 per group) were one by one put for 10 min maximum in the centre of the maze, but they were allowed to enter only 4 of the 8 open and baited arms; this was the "event-to-be-remembered". After visiting the four arms, the animal was returned to its cage and kept there for 2 (on week 3) or 4 hours (on week 5). The rats were then put again in the maze centre and allowed to complete arm choices 5-8 to obtain rewards in the 4 baited arms not visited before. In the working memory (WM) tests, WM errors meant re-entry into any of the arms visited in the first run. Week 4 (reference memory test): the feed reward was put only in the 4 arms preferred by the individual rats. Entering a non-baited (empty) arm constituted a reference memory error, from which performance was calculated. Week 6 and 7 (resting period): the animals were kept in the housing room, were exposed to the music once a day, but did not have any testing and were not exposed to new information. Week 8, 9 and 10 (long-term memory tests): in the 8th treatment week (recall), memory return was observed and in the 9th and 10th treatment week, 2- and 4-hours WM, respectively. The rats' spontaneous exploratory activity was investigated in an open field (OF) apparatus, measuring by infrared beam interruptions at the beginning, on the 5th and 10th week of it. There was a continuous white background noise (40 dB) and 25 lux illumination in the testing room. Rats, exposed to the acoustic exposure (Mozart music), tested by maze-learning capacity and memory performance, showed significant improvement of the short-term reference (59.76 +/- 4.24 vs. 75.36 +/- 5.53%, p=0.00155), in the return after the resting period (83.42 +/- 3.06 vs. 88.78 +/- 2.74%, p=0.01929), and 4-hour-interval long-term WM (60.52 +/- 2.49 vs. 65.97 +/- 2.87%, p=0.01258), control vs. musical group, respectively. The spontaneous locomotor activity of the control and music-exposed animals during the OF-test did not show significant differences. The urination and defecation activity during these mobility tests did not indicate any important difference between the emotional state of the control and music-treated rats. The subsequent classical (histo) pathological examination did not show any alterations, related to the musical treatment or substantial stress state. As a conclusion, this particular music in human hearing range was appropriate for improving learning capacity, but the spontaneous free-running movement practically did not change. In the present experiment the Mozart sonata proved to be efficient to improve some memory types without influencing the open-field results.