New study tries to decode how brains convert sounds into actions
Researchers from the Champalimaud Centre for the Unknown have discovered how the brain converts sounds to actions. These discoveries could someday help us unravel how the brain translates perceptions into actions.
The study’s foundation is to question how we make many daily decisions based on sounds without realizing it. The study helps us understand better how sensory information and behavioral choices are connected within the cortex.
This is the brain’s outer layer responsible for shaping our conscious perception of the world. The cortex is a part of the brain divided into different regions, each responsible for specific functions.
The sensory areas in the cortex process information from our surroundings, while the motor areas manage our actions. Interestingly, even though signals related to future actions are expected to be found only in motor areas, they also appear in sensory areas.
How do we perceive sound?
This raises the question of why movement-related signals are present in regions dedicated to sensory processing and when and where these signals emerge. By exploring these questions, the study authors sought better to understand the origin and role of these signals.
To achieve this, they conducted a study using mice.
The study’s lead author, Raphael Steinfeld, explained that they carefully designed a task for the mice to perform. In previous studies, the “Go-NoGo” task was often used, but it mixed signals related to specific movements with those related to general movements.
The mice were trained to decide between two actions to isolate signals for specific actions. They had to determine if a sound was high or low compared to a set threshold and indicate their decision by licking one of two spouts on the left or right side.
However, this wasn’t enough on its own.
“To separate brain activity related to the sound from that related to the response, we introduced a critical half-second delay. During this interval, the mice had to withhold their decision,” Steinfeld explained.
What is going on?
“Crucially, this delay allowed us to temporally separate brain activity linked to the stimulus from that linked to the choice and track how movement-related neural signals unfolded over time from the initial sensory input,” he added.
“We found that sensory- and choice-related signals displayed distinct spatial and temporal patterns,” Renart continues.
“Signals related to sound detection appeared quickly but faded fast, vanishing around 400 milliseconds after the sound was presented, and were distributed broadly across all cortical layers,” he stressed.
“In contrast, choice-related signals, which indicate the movement the mouse is about to make, emerged later, before the decision was executed, and were concentrated in the cortex’s deeper layers.”
“So, what might the origin of these choice signals in the auditory cortex be?,” notes explains Alfonso Renart, principal investigator and the study’s senior author.
“The early sensory signals in the auditory cortex don’t seem to predict the mice’s eventual choice, and the choice signals emerge significantly later,” added Renart. “This suggests that the sensory signals in the auditory cortex don’t directly cause the mice’s actions and that the choice signals we observe are likely computed elsewhere in higher brain regions involved in planning or executing movements, which then send their feedback to the auditory cortex.”
Source: Interesting Engineering
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New study tries to decode how brains convert sounds into actions