Dr's Casebook: Eyes can reveal the working of the blue spot in the brain.

Dr Keith Souter writes: Recent research from the Max Plank Institute of Human Development has shown that the pupil of the eye can tell you about what is happening inside the brain and give clues about how we focus attention on what is and what isn’t important.

The word pupil is itself intriguing. It actually comes from the Latin pupilla, meaning small doll.

The Romans called it this because one can see a reflection of oneself, like a small doll in the pupil of another.

Researchers at the Max Plank Institute are studying attentiveness and the way that a small cluster of cells, measuring a mere 15mm at the base of the brain regulate how we focus attention.

The small cluster is called the locus coeruleus, which literally means blue spot.

It is the main source of the neurotransmitter noradrenaline, which is known to control focus.

Understanding attention and focus is important.

Being attentive is vital when driving, or carrying out precision tasks where safety of self and others is crucial.

On the other hand a pedestrian may be walking along and daydreaming or thinking about shopping or what to have for tea.

That is inattentiveness.

But if a car suddenly peeps then attentiveness is instant.

Understanding just how the brain snaps to attention is important.

During states of inattentiveness, the brain is governed by slow, rhythmic fluctuations of neural activity, which are called alpha oscillations.

They are thought to suppress the active processing of sensory information so you can dissociate from the main task you are doing and think, daydream or plan your shopping or what to have for tea.

The blue spot is known to have a network of nerve fibres that reach throughout the brain.

It helps control memory, stress reaction and attention.

It has been found that fluctuations in pupil size are linked to activation of the blue spot at the base of the brain.

The researchers have found that during moments of larger pupil size, which is associated with noradrenaline activity and attentiveness, alpha oscillations disappear.

It seems that not only is the pupil a mirror, but it is a window into the working of the blue spot in the brain.