Odor has the power to transfer us across time and space. It could be the sweet scent of jasmine, or the moldy scent of algae. Unexpectedly, you are back at your youth house, or under the burning sun of a distant coast.
This association between smells and puts seems to be a deeply embedded aspect of human cognition. However how are the two connected in the brain? A research study released today (December 22, 2021) in the scientific journal Nature presents a possible description.
A Neural Link between Smell and Space
” Odour molecules do not inherently carry spatial information. Animals in the wild use smells for spatial navigation and memory, which permit them to locate valuable resources such as food,” stated Cindy Poo, the studys first author. “We wished to comprehend the neural basis of these behaviors, therefore we chose to study how the brain combines spatial and olfactory info.”
The researchers concentrated on the main olfactory cortex. “The olfactory system is distinct amongst the senses,” said the research studys senior author, Zachary Mainen, a primary investigator at the Champalimaud Centre for the Unknown in Portugal. “Only olfaction has direct reciprocal connections to the hippocampal system, which is associated with memory and navigation.”
Nerve cells in the primary olfactory cortex develop an odor-spatial map. Credit: Diogo Matias, Champalimaud Foundation
Hippocampal nerve cells are popular for functioning as “location cells.” Due to the fact that each cell ends up being active at a specific location within an environment, this is. Together, these neurons encode the whole area, efficiently developing a neural map of space. Hippocampal location cells, whose discovery in rats resulted in the Nobel Prize for Physiology or Medicine in 2014, are so trustworthy that researchers can inform where an animal is merely by observing their activity.
” We understand that the hippocampal system sends out signals to the primary olfactory cortex,” said Poo. “So we thought that this brain area might do more than simply identify different smells.”
Putting Olfactory Neurons to the Test
The rats sampled smells at the 4 ends of a plus-shaped labyrinth. “In this job, the rats had to discover and remember specific associations of areas and odors,” Poo described.
While the animals were fixing the puzzle, the researchers kept track of the activity of nerve cells in a part of the main olfactory cortex called the posterior piriform cortex. “By recording the electrical signals released by hundreds of specific neurons in this brain area, we were able to decode what specific nerve cells cared about.
” Our outcomes surpassed our expectations,” said Poo. “We had anticipated that some nerve cells here might appreciate location to a certain degree. “However, by carefully studying the activity of olfactory cortex neurons while the animal was navigating in the maze, we discovered that these neurons had actually found out an entire map of the environment.”
Olfactory Neurons Encode Spatial Maps
The researchers discovered a large population of nerve cells that, likewise to hippocampal place cells, became active at a particular location in the maze. Remarkably, the map didnt cover the entire environment similarly. Instead, it was largely restricted to behaviourally significant spots on the labyrinth: where the animals experienced the smells and received benefits.
” It appears that essential areas were found out through experience and encoded into a map. It was exceptional that these cells in the olfactory system started reacting in a provided place when no smells were present, even when the rat was simply walking not participated in the job,” Mainen included.
A Scent of Space
“We discovered that some neurons here reacted to smell, others to area, and yet others to both types of information to differing degrees. All these different nerve cells are mixed together, and are probably interconnected.
” This research study likewise opens up a brand-new window to comprehend how the senses are used for navigation and memory,” added Mainen. “Humans count on visual landmarks more than odors, however its likely that the concepts of how we remember where weve been and get to where were going are really comparable,” he concluded.
Recommendation: “Spatial maps in piriform cortex during olfactory navigation” by Cindy Poo, Gautam Agarwal, Niccolò Bonacchi and Zachary F. Mainen, 22 December 2021, Nature.DOI: 10.1038/ s41586-021-04242-3.
While the animals were resolving the puzzle, the researchers monitored the activity of neurons in a part of the main olfactory cortex called the posterior piriform cortex. “By recording the electrical signals given off by hundreds of specific neurons in this brain location, we were able to decode what specific nerve cells cared about. “However, by carefully studying the activity of olfactory cortex nerve cells while the animal was navigating in the labyrinth, we found that these nerve cells had actually found out an entire map of the environment.”
The scientists found a big population of nerve cells that, likewise to hippocampal place cells, became active at a specific place in the labyrinth. “We found that some nerve cells here reacted to smell, others to location, and yet others to both types of info to differing degrees.
