Research On The Neural Mechanism And Application Of The Effect Of Mozart’s Music On Spatial Memory

Since the 1990 s, increasing evidence has shown that there is a close relationship between music cognition and advanced brain function. Therefore, research on the music-cognition interaction has gradually become a hot topic in recent decades. In 1993,Rauscher and colleagues investigated the relationship between music and spatial reasoning and found that the subject’s spatial cognitive function increased after listening to Mozart K.448 or other similar music, namely the "Mozart effect". This effect has received widespread attention after it was reported. However, some research has questioned for the reliability of the "Mozart effect". In order to confirm the existence of the effect, many studies used different experimental paradigms in a variety of experimental conditions for empirical evidence. Some of them successfully replicated the effect, but some didn’t. The reasons for the instability of the effects mainly lie in the choice of experimental paradigms, musical works, and measurement tools. In additon, those that replicated the "Mozart effect" proposed different interpretations in the respect of its mechanism. Some of them suggested that listening to the music activates neurons in the brain and serves to “prime” the neural pathways of the subsequent spatial cognition task, leading to the improvement of spatial memory. Others argued that music preference contributes to the alteration of arousal while listening to the music, and thus improves learning and memory indirectly.In this dissertation, using positively and negatively structured music of Mozart K.448 as auditory materials, we first verified the existence of the "Mozart effect" in animal experiments employing behavioral and molecular neural biological technologies, and in human experiments as well; then, in order to study the characteristics of music structure producing the "Mozart effect", we focused on key musical elements underlying the effect; Finally, we branched out and investigated the effect of Mozart’s music exposure on the recovery of cognitive deficits in epilepsy. These studies are presented and discussed as follows:1. We used the retrograde Mozart K.448(the Mozart K.488 music notes to the opposite sequence) as a music control and ensure the same physical attributes of music. The subjects included 60 college students and 45 rats. By testing the spatial cognitive behavioral performance of rats and college students after listening to music, we found that Mozart music improved the subjects’ spatial cognitive ability, this has verified the existence of the "Mozart effect", meanwhile, retrograde Mozart K.448 may have a negative effect.2. We tested the expression levels of BDNF/TrkB and the number of newborn neurons related to learning and memory in developing rats, and found that being exposed to the Mozart music increased the expression of BDNF/Trk B in the hippocampus and auditory cortex and induced the neurogenesis in the dentate gyrus. On the contrary, the retrograde Mozart music reduced the protein expression levels of BDNF/Trk B and inhibited the neurogenesis in the same brain region. The results suggest that the "Mozart effect" could be attributed to up-regulating the expression level of BDNF/TrkB and promoting the increase of newborn neurons. Moreover, by examining the levels of BDNF/TrkB in the dorsal hippocampal subregions, we found that improvement of spatial cognition was related to increased expression of BDNF/Trk B in the dorsal hippocampus CA3 area and dentate gyrus, which suggests that the hippocampal subregions play differential roles in music cognition.3. In order to explore the influence of music structure on cognitive ability, we compared the essential structural components(i.e., pitch and rhythm) of the normal and retrograde Mozart’s music. In the animal behavioral experiment, we found that rhythm in the normal music improved subjects’ performance in the spatial memory test while retrograde rhythm reduced their spatial cognitive function. On the other hand, pitch did not produce any significant changes in the cognitive ability of rats. The results indicate that rhythm of music plays a key role in the "Mozart effect".4. Music therapy has been used in the treatment of clinical neurological disorders. We applied the "Mozart effect" to animal model research of temporal lobe epilepsy, and found that music exposure could improve the cognitive impariment in epilepsy and the effect was more significant at the early stage of the occurrence of epilepsy. This finding may provide new therapeutic strategies for dysfunction of nervous system.In conclusion, the current dissertation has verified the "Mozart effect" in the presence of reliability through animal and human experiments, confirmed that the key music elements of the effect is musical rhythm; In addition, we have revealed that retrograde music may have negative effects on individuals; based on the analysis of neurotrophic factors in the brain, we have explored the neuropsychological mechanism of the "Mozart effect" and extended the effect to serve as a potential adjuvant therapy tool for abnormal function due to nervous system disease. The work may help to speed up the understanding for human music cognition.