Effects of lemon essential oil aroma on the learning behaviors of rats

Abstract

Essential oils (EO) are volatile odors obtained from various plants. Their usage dates from ancient India and Egypt, and they have been used for more than 5 thousand years. The EO can be produced by distillation, expression, and CO2 high-pressure methods. Today, they are widely used for esthetic and therapeutic purposes by inhalation, oral administration, or through the skin. In the fields of medicine and psychiatry, under the name of “aromatherapy,” they are used in various fields, such as in emotion and control of mood, anxiolytics, antidepressants, alertness, improvement of memory, and in the treatment of cognitive disorders. Besides these usages, it is known that aroma is used to increase labor efficiency and to decrease labor errors.1 In addition to esthetic and therapeutic usages; their potential usages in the fields of behavioral attributes and learning has started to attract attention in recent years. Research in this field shows that aroma has important effects on attention level, cognitive performance, creativity, mathematical success and writing skills, task performance, robust perception, and memory. Moreover, it is stated that aroma may have important effects on learning efficiency, learning speed, and learning permanency by positively affecting the mood, which have an important place in directing human behavior. These effects occur through the connection of the olfactory nerve to the hypothalamus and limbic system.2 Lemon essential oil is produced by the cold expression method, and is a volatile fragrant oil. In traditional medicine, lemon oil is used for colds and to calm. In addition, recent studies have shown that lemon oil has anxiolytic, sedative, anti-spasmodic, and antidepressant effects. A study performed on humans showed that it improved creativity and mood and affected heart rhythm.3 The aim of this study is to investigate the effects of lemon essential oil as an aromatic stimulus on the learning behaviors of male rats