Abstract. Background: Exposure to music during pregnancy enhances brain development and improves learning in neonatal rats. Methods: In these experiments, we examined the effects of exposure to silence, hard rock, classical, and rap music in utero plus 60 days postpartum on learning and memory in adult Wistar rats. Passive avoidance learning (PAL) was assessed at age 60 days, and a retention test was done 24 hours after training. Elevated plus maze (EPM) was also used as a standard behavioral task for assessing the effects of music therapy on anxiety. Furthermore, we measured serum corticosterone levels and adrenal weight at the end of experiments to show the possible effect of stress on the rats’ behavior. Results: Hard rock music impaired acquisition, increasing the number of trials to acquisition in PAL task. Hard rock music also impaired the retrieval process by decreasing step-through latency and increasing time spent in the dark compartment during the retention trial. Further, in the hard rock group, there were increases in serum corticosterone and adrenal weight of rats. Classical music, in turn, improved acquisition learning and retention memory and decreased serum corticosterone levels compared to the silence group. Rats’ exposure to rap music did not show any significant change in acquisition and retrieval processes compared to the silence group. In the EPM task, classical music exposure had anxiolytic-like effects revealed in an increase in the number of entries into open arms and time spent in the open arms. However, in this task, hard rock music induced an anxiogenic effect. Conclusions: Prenatal and postnatal exposure to music improves PAL and memory in adult rats. The effects of music therapy with classical music might be related to stress reduction by lowering corticosterone as a stress biomarker or anxiolytic effects; this deserves further examination.

Disorder in chewing food is a major problem in patients with stroke, some of those who suffer from brain lesion, multiple sclerosis, and other diseases such as head and neck cancer. This kind of disorder causes significantly decreased food consumption and consequently malnutrition or dehydration and in severe cases leads to suffocation. It can also increase the rate of death during the first year after the stroke to 45%. Therefore, finding an appropriate and common pattern of cooperation of jaw muscles in the act of chewing can have a very important role in assisting the process of rehabilitation in these patients. In this article, to improve current rehabilitation techniques for patients with chewing problems, attempts have been made to investigate the physiology of human chewing and involved muscles in this process. Extracting synergy patterns of jaw muscles during chewing action was also carried out in this article using analysis of the main components of electromyogram signal and quantification of muscle activity. The results show that each individual applies the same motion during different times for chewing action. Moreover, cooperation and interaction of the involved muscles are maintained in this process during various times in which the share of masseter muscle is more than temporal one in this collaboration.

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