Divide et impera, divide and conquer, a motto used by Caesar, Napoleon,… but also by our brains? University of Queensland (UQ) researchers have found human brains ‘divide and conquer’ when people learn to navigate around new environments.
From the press release:
The study found that the mental picture people create to help navigate to a new location is split into two sections.
The size of the environment is coded by one area of the brain and its complexity is coded in another.
QBI postdoctoral research fellow and lead researcher Dr Oliver Baumann said the work shed new light on how learning the layout of a new environment, and then accessing this information from memory, was represented in the brain.
“We’ve known for some time that a part of the brain called the hippocampus is important for building and maintaining cognitive maps,” he said.
“The results of our study have shown for the first time that different aspects of a learned environment – specifically its size and complexity – are represented by distinct areas within the hippocampus.”
QBI Cognitive Neuroscience Laboratory Head Professor Jason Mattingley said the findings could have important implications for people suffering from spatial memory impairments.
“This research is important for understanding how our brain normally stores and manages spatial information,” Professor Mattingley said.
“It also gives us clues as to why people with memory loss due to Alzheimer’s disease often become lost in new or previously familiar surroundings.”
Dr Baumann said 18 people navigated their way through three virtual mazes that differed either in the number of corridors through which they could travel or the length of the corridors.
After learning the task, the participants were asked to recall mental maps from each of the mazes while their brain activity was measured using functional magnetic resonance imaging.
“We found that one region in the hippocampus was more active when participants recalled a complex maze in which there were many corridors to choose from, irrespective of the overall size of the maze,” Dr Baumann said.
“Conversely, we found that a separate area of the hippocampus was more active when the overall size of the maze increased, regardless of the number of corridors.”
Abstract of the research:
The hippocampus is widely assumed to play a central role in representing spatial layouts in the form of “cognitive maps.” It remains unclear, however, which properties of the world are explicitly encoded in the hippocampus, and how these properties might contribute to the formation of cognitive maps. Here we investigated how physical size and complexity, two key properties of any environment, affect memory-related neural activity in the human hippocampus. We used functional magnetic resonance imaging and a virtual maze-learning task to examine retrieval-related activity for three previously learned virtual mazes that differed systematically in their physical size and complexity (here defined as the number of distinct paths within the maze). Before scanning, participants learned to navigate each of the three mazes; hippocampal activity was then measured during brief presentations of static images from within each maze. Activity within the posterior hippocampus scaled with maze size but not complexity, whereas activity in the anterior hippocampus scaled with maze complexity but not size. This double dissociation demonstrates that environmental size and complexity are explicitly represented in the human hippocampus, and reveals a functional specialization for these properties along its anterior–posterior axis.