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Mixed signals: How the brain interprets social cues

image of neural pathways stained green
Neural pathways, stained neon green above, carry smell signals through the mouse brain from the basal amygdala to the auditory cortex.

Imagine you鈥檙e at a dinner party, but you can鈥檛 smell the food cooking or hear the dinner bell. Sounds like a dream, right? What if it wasn鈥檛?

鈥淲hen we experience the world and interact with people, we use all our senses,鈥 LaboratoryProfessor Stephen Shea says. 鈥淭hat鈥檚 true for animals and humans.鈥 However, that鈥檚 not always the case in developmental disorders like autism. These conditions can affect how the brain processes incoming information, making it difficult to interpret the social cues that drive conversations, dates, and other interpersonal activities.

Exactly how such signals mix and influence each other in the brain isn鈥檛 well understood. To shed light on the subject, Shea and graduate student Alexandra Nowlan traced how smell and hearing interact in mouse brains during a maternal behavior called pup retrieval. This activity isn鈥檛 limited to mothers. It can also be learned by surrogates. Think stepmoms and babysitters. Shea explains:

鈥淧up retrieval is one of the most important things for mothers or caregivers. It requires the ability to smell and hear the pup. If these things are both important, that may mean they merge somewhere in the brain. One interesting thing we found was a projection from a location called the basal amygdala (BA).鈥

In mice and humans, the BA is involved in learning and processing social and emotional signals. During pup retrieval, the team found that BA neurons carry smell signals to the brain鈥檚 hearing center, the auditory cortex (AC). There, they merge with incoming sound signals and influence the animal鈥檚 response to future sounds鈥攍ike pups鈥 cries. Amazingly, when Shea鈥檚 team blocked maternal mice from accessing smell signals, their pup retrieval response almost completely broke down.

image of medial geniculate
The Shea lab traced neural pathways connecting the AC to several other parts of the brain, including the medial geniculate (seen here), which is thought to help direct and maintain attention.

鈥淲e think what鈥檚 reaching the AC is being filtered through social-emotional signals from BA neurons,鈥 Shea explains. 鈥淭hat processing can be impaired in autism and neurodegenerative conditions. We think many parts of the brain participate in this behavior and that it鈥檚 very richly controlled.鈥

Shea鈥檚 lab is now exploring how these brain regions connect and interact with one another. Their work may lead to a better understanding of how autism can affect a person鈥檚 ability to interpret social cues. But that鈥檚 just the beginning.

鈥淭丑别 idea that we found a neural circuit that may allow emotional processes to directly interact with perception is very exciting to me,鈥 Shea says. He鈥檚 not alone there. His research might yet provide answers to one of humanity鈥檚 oldest questions. How do our senses inform the ways we connect with one another and experience the world?

Written by: Nick Wurm, Communications Specialist | wurm@cshl.edu | 516-367-5940


Funding

National Institute of Mental Health, C.M. Robertson Foundation

Citation

Nowlan, A.C., et al., 鈥淢ultisensory integration of social signals by a pathway from the basal amygdala to the auditory cortex in maternal mice鈥, Current Biology, December 3, 2024. DOI:

Core Facilites

Animal Facility 鈥淭丑别 Animal Shared Resource houses and cares for the animals essential for scientific research. Our staff perform all aspects of animal husbandry, ensure humane care, and assist researchers with highly technical procedures and protocol design and development.鈥 鈥 Animal Facility Director and Attending Veterinarian Rachel Rubino, DVM

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Principal Investigator

Stephen Shea

Stephen Shea

Professor
Ph.D., University of Chicago, 2004

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