Scientists decode how brain senses direction and location

A critical component involved in establishing direction process is the set of neurons called “head direction cells”.

These cells act like a compass based on the direction the head is facing. They are located in the thalamus,a structure that sits on top of the brainstem,near the centre of the brain.

Neurons called “place cells” work to establish location relative to some landmarks or cues in the environment. The place cells are found in the hippocampus,part of the brain’s temporal lobe.

Studies were conducted using implanted microelectrodes that enabled the monitoring of electrical activity as these different cell types fired.

The research found that the two populations the head direction cells and the place cells talk to one another.

“They put that information together to give you an overall sense of ‘here’,location wise and direction wise. That is the first ingredient for being able to ask the question,’How am I going to get to point B if I am at point A?’ It is the starting point on the cognitive map,” said Taube,a professor in the Department of Psychological and Brain Sciences.

The study checked the responses of the spatial navigation system when an animal made an error and arrived at a destination other than the one targeted – its home refuge,in this case.

The researchers described two error-correction processes that may be called into play resetting and remapping¿differentiating them based on the size of error the animal makes when performing the task.

When the animal makes a small error and misses the target by a little,the cells will reset to their original setting,fixing on landmarks it can identify in its landscape.

“We concluded that this was an active behavioural correction process,an adjustment in performance,” Taube said.

“However,if the animal becomes disoriented and makes a large error in its quest for home,it will construct an entirely new cognitive map with a permanent shift in the directional firing pattern of the head direction cells. This is the ‘remapping’,” he said in a statement.

Taube said that others have talked about remapping and resetting,but they have always regarded them as if they were the same process.

“What we are trying to argue in this paper is that they are really two different,separate brain processes,and we demonstrated it empirically,” he said.

The study was published in the journal Nature Neuroscience.