Researchers have discovered that in the mouse brain’s auditory center, signals from smell and sound combine, affecting social behaviors such as retrieving young mice (pups). This finding could enhance our understanding of how neurological disorders, like autism, impact a person’s ability to grasp social signals.
Picture yourself at a dinner gathering, unable to detect the aroma of the cooking food or the sound of the dinner bell. Sounds appealing, right? But what if it turned out to be a nightmare?
According to Stephen Shea, a professor at Cold Spring Harbor Laboratory, “As we navigate the world and engage with others, we rely on all our senses. This applies to both animals and humans.” Unfortunately, this multi-sensory experience is not always the case for individuals with developmental disorders like autism. Such disorders can hinder the brain’s ability to process sensory information, making it challenging to understand the social signals crucial for communication, dating, and other interactions.
However, the specifics of how these sensory signals interact in the brain remain unclear. To investigate this, Shea and graduate student Alexander Nowlan studied the interplay between smell and hearing in mouse brains during a maternal instinct known as pup retrieval. This behavior is not exclusive to biological mothers; it can also be adopted by caregivers such as stepmoms and babysitters.
“Pup retrieval is essential for mothers and other caregivers as it requires both olfactory and auditory detection of the pups. The merging of these senses suggests a common processing area in the brain. One noteworthy discovery was a projection from an area called the basal amygdala (BA),” Shea explains.
In both mice and humans, the BA plays a role in processing emotional and social signals. During the pup retrieval process, the researchers found that neurons in the BA transmit smell signals to the auditory cortex (AC), the part of the brain responsible for processing sounds. Here, these signals blend with incoming auditory information, shaping how the animals respond to subsequent sounds, such as the cries of their pups. Remarkably, when Shea’s team prevented maternal mice from receiving smell signals, the mice’s ability to retrieve their pups almost entirely failed.
“We believe that the signals reaching the AC undergo filtering through social-emotional signals from BA neurons,” Shea states. “This type of processing could be disrupted in autism and neurodegenerative diseases. Various brain regions likely contribute to this behavior, and it is exceptionally well-regulated.”
Currently, Shea’s lab is investigating the connections and interactions between these brain regions. Their research may help clarify how autism affects the ability to interpret social cues, but this is merely the tip of the iceberg.
“The discovery of a neural circuit that may facilitate the direct interaction between emotional processes and sensory perception is incredibly thrilling to me,” says Shea. He shares this excitement with others as this research could potentially address one of humanity’s fundamental questions: How do our senses shape our connections with one another and how we perceive the world?
