04/20/2021 at 08:00 CEST
In two different and parallel investigations, scientists from Princeton University in the United States have discovered a kind of magic trick that the brain does to combine two permanent and simultaneous sources of information that can confuse us.
One of the permanent sources of information is that which comes from the senses, which forces the brain to process and react according to stimuli.
The other source of information is that which comes from our memory, which stores simultaneous memories of each of the experiences.
The brain carries out its daily activity in the midst of this crossing of information and has to ensure at all times that the decisions we are going to make are the most appropriate, whether it is choosing a car park or greeting an acquaintance or not.
Crucial interactionsThe decisions we make on a daily basis depend on the instantaneous interactions that occur between these two strategic cognitive functions: perception and memory.
Perception is the first stage of the cognitive process: through it we apprehend everything that happens in the environment. The second stage is memory, since we remember in the short term everything that we are living and experiencing.
However, the information that comes from both sources must be managed in parallel: if they are mixed, perception can be confused with memories stored in memory and cause confusion and poor decisions.
A spontaneous process complicates the task of managing perception and memory separately: the neural regions involved in both processes share information from both sources.
Computing dilemmaHow, then, does the brain manage to solve with the brilliance that characterizes this “computerized” dilemma?
It was discovered, not without surprise, by the two teams of scientists: the brain flips sensory information to encode it as a memory.
It is as if you write the sensory information that you need to analyze on one side of a sheet of paper. Then he turns the sheet of paper over to write the memory associated with the memory of the sensory experience on the other side.
In other words, when we perceive something that the brain needs to process, such as the aroma of a flower, that information carries the seed of a memory that will be preserved in our memory and will be activated every time we see a flower.
Related topic: Memories modify our perception of reality
Two faces of the same neuron
Two faces of the same neuronThe information that reaches the brain is therefore two-dimensional and what the brain does is write the sensory information on one side and the information associated with the memory of that sensation, on the opposite side.
In the same neuronal sheet it files everything, in such a way that, although separated from each other, perception and memory remain together in the neural recesses forming a memory.
When the time comes to use these registers, the brain consults the information stored on both neural faces: on one face it obtains the information from the experience. Then you flip it over and get the associated memory. Next, guide our behavior.
Mouse experimentTo study how sensory inputs and memories are represented, the researchers recorded the activity of neurons in the auditory cortex of mice as they learned sequences of sounds.
They discovered a population of neurons that recorded sensory inputs and memory of recent stimuli, in two orthogonal (perpendicular) dimensions, equivalent to the two sides of the same sheet of paper.
In one of the dimensions, a combination of stable neurons stored the sensory information. In the other dimension, other “switch” neurons encoded the sensory information.
Together, these neuronal responses rotated the representation of the neuron population 90 degrees, transforming sensory inputs into memory, sensations into memories.
The theoretical model developed by the researchers demonstrated that this rotational dynamics is an efficient mechanism for generating orthogonal representations, thus protecting memories from sensory interference, and vice versa.
Even moreIn another parallel investigation, part of the same team from Princeton University developed another similar study with Rhesus macaques and reached the same conclusion.
He discovered that the neurons focused on sensory stimuli in monkeys are the same neurons that focus on memory, and that the neural representations of memories associated with the experience are dynamically rotated to be encoded as memory on the other side of the nerve cells they record. sensory stimuli.
These findings, the journal Quanta highlights, fuel an emerging trend in neuroscience: that populations of neurons, even in lower sensory regions, are involved in richer dynamic coding than previously thought.
Rotational dynamics reduces interference between sensory and memory representations. Alexandra Libby & Timothy J. Buschman. Nature Neuroscience (2021). DOI: https: //doi.org/10.1038/s41593-021-00821-9
Shared mechanisms underlie the control of working memory and attention. Matthew F. Panichello & Timothy J. Buschman. Nature (2021). DOI: https: //doi.org/10.1038/s41586-021-03390-w
Top photo: chenspec. Pixabay.