Your brain tracks time constantly and when you’re involved in an event, your brain immediately records the time, the place, and where it happened. These memories are called episodic memories and can disappear when brain areas responsible for memory formation become damaged or diseased.
Indeed, both Alzheimer’s disease and dementia are conditions in which memories degrade and then disappear over time. Several brain structures, most notably, the medial temporal lobe containing the hippocampus is where memories of events are made and stored.
In addition, neurons and cells involved in tracking time are also found here.
The question is whether there is a connection between your brains ability to track time, memories and Alzheimer’s disease?
Your Brain Tracks Time: Study Investigates Connection To Alzheimer’s
Drs. James Heys and Daniel Dombeck investigated whether hippocampus brain cells also help track time. The research was supported by the National Institute of Mental Health (NIMH).
Mice ran on a treadmill surrounded by a virtual reality screen. The mice saw a virtual track as they ran. Using a brain imaging technique, the researchers tracked neuron activity in the medial cortex.
As the mice made their way through the track, they came upon an invisible door they couldn’t run past. If they did, they had to start the track over. To open the door, they had to wait at least 6 seconds without moving. If they moved before 6 seconds, they had to start the wait time over. Once the mice figured out how long to sit still to open the door, they could complete the track and receive their reward.
When the animals were running through the track, the specific set of cells responsible for recording spatial information were active. Once the mice stopped at the invisible door, those cells turned off and a different set of cells became active. These new cells appeared to keep track of how long the mice waited for the door to open. The ensemble of these timing cells predicted how long the mice waited.
Your Brain Tracks Time: Study Results, Part II
Next, the mice were given a different virtual track to run through, and many of the same neurons responded to the same spatial and time components. This suggests that there are two separate sets of brain circuits in the medial cortex that are specifically tuned to record either time or spatial information.
These finding are similar to what happens o people with Alzheimer’s disease. Patients with Alzheimer’s forget when things happened in time. And, the medial cortex in the hippocampus part of the brain is one of the first brain regions affected by the Alzheimer’s disease.
This finding might lead to new early-detection tests for Alzheimer’s, say the study authors.
“We could start asking people to judge how much time has elapsed or ask them to navigate a virtual reality environment—essentially having a human do a ‘door stop’ task”, says Dr Heys.