Understanding Moods and Anxiety

Many years of scientific research has helped us to understand how even such things as moods, thoughts and feelings are regulated in distinct brain regions. However, we are still a long way from fully understanding the mysteries of the brain.

Where in the brain do moods and feelings of anxiety come from?

The brain contains a series of structures that are involved in emotional regulation, motivation and memory, and are known as the "limbic system". The limbic system consists of many interacting structures, but most importantly, the hippocampus, amygdala and hypothalamus. (Figure 2). These structures are located deep inside the brain, under the cortex.

The amygdala is most commonly associated with fear and anxiety-related behaviour. The amygdala receives information involved in the recognition of fear, and in the memory of fear. Signals are then sent from the amygdala to other brain areas to initiate the appropriate response. Lesions of this area have a calming effect, whereas stimulation of this area induces fear, anxiety and increased vigilance. Recent evidence suggests that the amygdala may also be involved in the recognition of rewards and positive experiences as well.

The hippocampus is a large structure in the brain involved in many aspects of memory, especially storage and retrieval of information on spatial and environmental context, and linking this information with emotional memory. The hippocampus is a special region of the brain in that it is one of only a few areas in the brain where neurogenesis occurs. Neurogenesis is the formation of new nerve cells. The hippocampus is also vulnerable to the damage induced by chronic stress. As a result, the hippocampus is also implicated in mood disorders.

The hypothalamus, along with the pituitary gland, is a structure involved in maintaining homeostasis (a steady state) in basic bodily functions such as temperature regulation, feeding, drinking, and the regulation of hormones involved in stress.