You are on the way to your cubicle, coming back from the cafeteria, when you run into Nick. He says he has to fly to Vancouver for a meeting with the solar panel supplier for the new power station project.
Nick knows you’ve been to Vancouver a few times to visit your brother, so he asks you to recommend a couple good restaurants to hit when he’s in there.
Your brain scans thru all the times you were there, cross references the places you ate, and compares them. The whole process, which takes only a few seconds, involves at least two different kinds of memory and neurons called memory-trace cells.
“Memory requires more than the mere dating of an event in the past. It must be dated in my past” - William James
Spatial Cognition And Episodic Memory
Episodic memory is the storage and recollection of observational information linked to specific events in your life. Episodic memory acts like mental time travel. Recollecting details of previous experiences1, it relies on structures in the brain’s medial temporal lobe, such as the hippocampus and the entorhinal cortex.
The same areas are also important for spatial cognition and memory - the kind of memory that contains information about your environment as well as information about the interconnections between objects and landmarks in your environment.
But how do we align the location in space of a memory with it’s specific location in time?
Research from 2013 suggests that our brains mark memories using tags that have information about where and when a memory was formed.
Research in mice has shown that within the hippocampus, neurons called place cells fire when the animals are in a specific location, or even if they are dreaming about that location.
But you might be more likely to tell Nick to check out the Italian bistro where you had that moist chocolate cake stuffed with vanilla bean ice cream for desert, a new study3 from researchers in The Netherlands suggests. They found that people remember the locations of high calorie foods more accurately than low calorie foods.
Chocolate Brownies vs. Cucumbers
In the research, Rachelle de Vries, MSc, and colleagues at Wageningen University had 512 study participants follow a fixed route around a room. The route featured either eight food samples or eight food-scented cotton pads placed in different locations.
When the participants reached a sample, they tasted the food (or smelled the cotton pad) and then rated how much they liked the sample. Food and odour samples included apples, potato chips, cucumbers and chocolate brownies.
Participants then had to pinpoint the location of each food or food odour sample on a map of the room.
The participants were around 27% closer when they were mapping high calorie foods than when they were mapping low calorie foods to the actual location. The results suggest that the spatial memory of humans is optimized for finding high calorie foods.
For about 99 percent of human evolution, our ancestors were hunter-gatherers inhabiting a highly complex and variable physical food environment, where food sources varied on both spatial and temporal availabilities. A cognitive adaptation that could have evolved to optimize foraging efforts within such erratic food habitats of the past is a high-calorie bias in spatial memory. Such an inbuilt spatial bias entails the automatic registration and prioritization in memory of high-calorie food locations. This would have enabled foragers to efficiently navigate toward valuable calorie-dense resources – without competing for limited attentional capacities required in other important activities such as avoiding predation. Indeed, a similar mechanism has been observed in other animal species,
the authors write.
James E. Kragel, Neal W Morton1, and Sean M. Polyn Neural Activity in the Medial Temporal Lobe Reveals the Fidelity of Mental Time Travel The Journal of Neuroscience, 18 February 2015, 35(7): 2914-2926; doi: 10.1523/JNEUROSCI.3378-14.2015 ↩︎
Qasim, Salman E., Jonathan Miller, Cory S. Inman, Robert E. Gross, Jon T. Willie, Bradley Lega, Jui-Jui Lin, et al. Memory Retrieval Modulates Spatial Tuning of Single Neurons in the Human Entorhinal Cortex. Nature Neuroscience 22, no. 12 (December 2019): 2078–86. ↩︎
de Vries, R., Morquecho-Campos, P., de Vet, E. et al. Human spatial memory implicitly prioritizes high-calorie foods. Sci Rep 10, 15174 (2020). ↩︎