How smells affect the brain's decision-making mechanism

summary: Researchers have discovered a new function for the hippocampus in decision-making, showing that specific brain cells, known as 'time cells', are stimulated by odors to facilitate quick decision-making.

This study shows how rats learned to associate fruity odors with reward, resulting in faster and more efficient decision-making.

By tracking the activation of these cells in response to odors, the team revealed a direct link between odor, hippocampal function, and associative learning, suggesting that these cells play a critical role beyond memory retrieval, and directly influence decision-making in the brain.

Key facts:

1. The study identified “time cells” in the hippocampus as key players in the brain's decision-making process, which are stimulated by specific odors to stimulate quick decision-making.
2. The mice were able to associate fruity odors with positive outcomes, demonstrating how odor cues can enhance the learning of decision-making behaviors.
3. This research sheds light on the complex relationship between sensory perception and cognitive processes, and reveals new insights into the role of the hippocampus in associative learning and decision making.

source: University of Colorado

Researchers at the University of Colorado Anschutz Medical Campus have discovered that scents stimulate specific cells in the brain that may play a role in rapid decision making.

The study was published online Tuesday in the journal Current biology.

The scientists focused on the hippocampus, an area of ​​the brain important for memory and learning. They knew that so-called “time cells” played a key role in hippocampal function, but they did not know their role in associative learning.

“These cells will remind you to make a decision — do this or do that,” said study senior author Diego Restrepo, a neuroscientist and professor of cell and developmental biology at the University of Colorado School of Medicine.

The researchers observed that when mice were given the option to respond to the fruit scent by licking a faucet that delivered sweet water, they quickly learned to lick the fruit scent rather than the mineral oil scent.

“They have to associate the smell with the outcome of what they do, and that's why they learn to make a decision,” said Ming Ma, Ph.D., first author of the study and a senior instructor in cell and developmental biology at CU. Medicine. “When it smells fruity, they lick and get a reward. When it comes to mineral oil, they stop licking.”

“The more they learned, the more the cells were stimulated which led to faster decoding of odors and allowing the mice to quickly become skilled at selecting fruity odors,” said Fabio Simoes de Souza, Ph.D., another first author of the study. Assistant Research Professor of Cell and Developmental Biology at CU School of Medicine.

The stimulus for decision-making is the smell that is transmitted through the nose to send nerve signals to the olfactory bulb and to the hippocampus. The two devices are closely linked. Information is processed quickly and the brain makes a decision based on the input.

“Before that, we didn't know that there were decision-making cells in the hippocampus,” Restrepo said. “The hippocampus is a multitasker.”

Restrepo speculated that the cells are not always turned on, otherwise the stimuli may become overwhelming.

This study expands current knowledge about what goes into the brain's decision-making process, specifically those quick, no-holds-barred decisions that humans and mice make all the time.

“The hippocampus turns on time cells to predict the decision, which can give you a glimpse into what you should remember,” Restrepo said. “In the past, time cells were thought to only remind you of events and time. Here we see memory encoded in neurons and then retrieved immediately when a decision is made.

About this neuroscience research news

author: David Kelly
source: University of Colorado
communication: David Kelly – University of Colorado
picture: Image credited to Neuroscience News

Original search: Open access.
“Sequential activity of hippocampal CA1 cells forms a temporal memory map for associative learning in mice“By Diego Restrepo et al. Current biology

a summary

Sequential activity of hippocampal CA1 cells forms a temporal memory map for associative learning in mice

Neural sequential dynamics encoded by time cells play a crucial role in hippocampal function. However, the role of hippocampal sequential neural dynamics in associative learning is an open question.

We used two-photon Ca²⁺ Imaging of dorsal CA1 (dCA1) neurons in the stratum pyramidale (SP) in head-fixed rats performing an associative learning task does not go to investigate how odor valence is temporally encoded in this brain region.

We found that SP cells responded differently to a rewarding or unrewarding odor. The stimuli were accurately decoded by the activity of the neural population, and accuracy increased dramatically as the animal learned to discriminate between the stimuli.

Decoding the stimulus from individual differentially responding SP cells revealed that decision making occurred at discrete times after stimulus presentation. Prediction of licking was decoded from the activity of a cell population in dCA1 that was linearly related to licking behavior.

Our findings indicate that sequential activity of SP cells in dCA1 forms a temporal memory map used for decision making in associative learning.