YOUR BRAIN’S INTERNAL CLOCK

THE INTERVAL TIMER THEORY EXPLAINS HOW YOUR BRAIN KEEPS TIME LIKE A NEUROLOGICAL METRONOME.

START THE CLOCK 01

A ‘start’ signal is activated by the onset of an event that lasts a familiar amount of time, such as the three minutes it takes to boil some water in a kettle.

SYNCHRONISATION 02

This triggers specific cortical nerve cells (which usually fire at different speeds, shown in A) to briefly fire together at the same time (B). They then return to their original firing rates, but because they all started simultaneously their activity follows a particular pattern.

DOPAMINE 03

A subtype of brain cells called spiny neurons monitor the cortical neurons’ activity, keeping track of how many times their firing patterns repeat. When the event finishes — in this case, once the kettle has boiled — bursts of dopamine are sent towards the striatum.

MEMORY 04

The release of dopamine causes the spiny neurons to commit the firing pattern of the cortical neurons at that particular instant to memory. This creates a kind of ‘time stamp’ for the given event. Research suggests that there are unique memories for a whole range of different intervals.

TIME’S UP 04

Now the spiny neurons have ‘learned’ these intervals they will monitor cortical firing rates until they match the memory for the time stamp that signals that particular event is over. Once this occurs the striatum sends signals to other areas of the brain involved in memory and decision making, giving you an internal ‘time’s up!’ alert.