Biology and Psychology of Essential Oils - Chapter 10 Notes

Introduction

• Aromatherapy's therapeutic effect is often linked to essential oil aromas, suggesting a treatment involving smell.

Anosmia

• Olfaction significantly affects the quality of life.
• Anosmia: Loss of the ability to smell.
• Temporary anosmia: caused by sinusitis, allergies, cold, and flu.
• Main causes of anosmia:
  • Head injuries or trauma.
  • Viral infections (can cause total loss of smell).

Basic Overview of Olfaction (pg. 112-116)

• Olfaction starts in the nasal cavity and goes through cilia and olfactory neurons to the olfactory bulb.
• The olfactory bulb processes the initial olfactory message and sends it to the brain.

Olfactory Bulb

• Targets in the brain:
  • Primary olfactory cortex: Olfactory discrimination, perception, and memories.
  • Limbic system: Activates smell-related emotions and behaviors.
• Olfactory messages are initially processed and sent to higher olfactory areas in the brain.

Limbic System

• Often referred to as the “nose brain”.
• Key role in the expression of emotion.
• Together with the hypothalamus, governs primitive and emotional drives (sex, thirst, hunger).
• Evokes behavioral mechanisms: rage, fear, sorrow, revulsion, physical affection, and sexual attraction.

Hypothalamus

• Crucial role in controlling the autonomic nervous system.
• Regulates visceral functions: heart rate, blood pressure, respiration.
  • Sympathetic.
  • Parasympathetic.
• Regulates body functions and activities during stress.
• Essential oils can influence the limbic system and hypothalamus, aiding in stress management.

Odours and Memory Associations

• "Smell is a potent wizard that transports you across thousands of miles and all the years you have lived." - Helen Keller
• Long-term odour memory is often stronger than long-term visual memory.