Stress is a well-known factor influencing mental health, but its impact extends beyond psychiatric disorders. It can also reshape the way we perceive the world, from heightened sensitivity to noise to an increased awareness of irritating textures and odors.
A recent study published in PLOS Biology sheds light on how repeated stress alters auditory processing in mice, offering new insights into how chronic stress may affect human sensory perception.
The Study: Examining the Link Between Stress and Hearing
The research, led by Ghattas Bisharat and colleagues at Ben-Gurion University of the Negev, sought to determine how repeated exposure to stress affects the brain’s ability to process sound. The team subjected mice to a mild but persistent stressor—being confined in a small space for 30 minutes daily over the course of a week. Following this repeated stress, the researchers measured changes in the mice’s auditory perception and neural activity.
The study revealed that while the mice’s basic hearing ability remained intact at the auditory brainstem level, their auditory cortex exhibited significant changes. Specifically, the researchers observed an increase in spontaneous neuronal activity in the auditory cortex, coupled with altered responses in specific types of inhibitory and excitatory neurons.
One of the key behavioral findings was that stressed mice showed a diminished perception of loudness. In a task requiring them to categorize sounds as loud or soft, they were more likely to misidentify loud sounds as soft. This suggests that chronic stress can impair the brain’s ability to accurately assess sound intensity, potentially leading to changes in how individuals perceive their environment.
Neural Changes: A Closer Look
At a neurological level, the study found distinct shifts in how different types of neurons responded to sound:
- Parvalbumin-expressing neurons (PV cells) and pyramidal neurons showed a reduced sensitivity to auditory stimuli, meaning that their activity in response to sound was dampened after stress.
- Somatostatin-expressing inhibitory neurons (SST cells) exhibited an increased response to sound, possibly contributing to the altered perception.
These findings indicate that stress-induced changes in auditory perception are not due to damage in the hearing pathway but rather result from shifts in how the brain processes auditory information.
The Gradual Impact of Chronic Stress
One of the most striking findings of the study was that the effects of stress on hearing did not occur immediately but developed gradually over the week of repeated exposure. This suggests that prolonged stress leads to cumulative neural adaptations that reshape sensory perception over time.
Fig 1. Physiological and behavioral evidence of stress. (a) Corticosterone levels increased significantly after 30 minutes of restraint stress and remained elevated over a week of repeated stress. (b) Pre-restraint corticosterone levels showed a slight increase over time. (c) Stressed mice exhibited reduced movement in open-field tests, with no signs of adaptation between the first and seventh day. (d) Schematic of two-photon imaging setup, showing cortical activity tracking during baseline and stress conditions. Source: Bisharat, et al, PLOS Biology
Previous studies have shown that stress can heighten responses to emotionally charged stimuli, such as threats or pain. However, this study demonstrates that stress can also alter the perception of neutral stimuli—such as everyday sounds—potentially affecting how individuals interact with their environments.
Potential Implications for Human Hearing and Mental Health
While this study was conducted in mice, the findings raise important questions about how chronic stress might affect human hearing and sensory processing. Heightened or altered sound perception has been reported in individuals with anxiety disorders, PTSD, and stress-related conditions, suggesting a potential parallel to the effects observed in mice.
For example, individuals experiencing chronic stress or anxiety often describe being more easily startled by loud noises or feeling overwhelmed in noisy environments. This could be due, in part, to the same type of cortical changes observed in the study.
The study’s findings highlight the potential importance of stress management in maintaining not just mental well-being but also sensory processing and perception.
Understanding how stress alters brain function may help in developing interventions to mitigate its negative effects, whether through therapeutic strategies, stress reduction techniques, or potential treatments that target auditory processing pathways.
As scientists continue to unravel the complex relationship between stress and sensory processing, studies like this offer crucial insights into how our brains adapt to prolonged challenges—and how these adaptations can influence the way we experience the world.
Reference:
Bisharat, G., Kaganovski, E., Sapir, H., Temnogorod, A., Levy, T., & Resnik, J. (2025). Repeated stress gradually impairs auditory processing and perception. PLOS Biology, 23(2), e3003012. https://doi.org/10.1371/journal.pbio.3003012
