American Journal for Young Scientists · ISSN 3068-9015
A Coupled HPA–Mirror Neuron Model of Chronic Maternal Stress and Autism Susceptibility
Authors: Bhavya Dwivedi
Published: September 26, 2025
Category: Computational Neuroscience
Abstract
Stress experienced by a mother during pregnancy can profoundly influence the neurodevelopment of the fetus, potentially increasing susceptibility to autism spectrum disorders. We investigate these effects by extending a minimal mathematical model of the hypothalamic–pituitary–adrenal (HPA) axis to include mirror neuron activity in the premotor cortex. Our coupled system of differential equations captures the short-term (acute) versus long-term (chronic) impacts of maternal stress on embryonic development. We show that acute stress causes transient elevations in cortisol and mild alterations in mirror neuron activity, whereas chronic stress yields persistent physiological changes—elevated adrenal gland mass, higher baseline cortisol levels, and diminished mirror neuron activity that can remain even after the stressor is removed. Through phase-portrait and fixed-point analysis, we identify a key parameter, D, which governs the dynamics of mirror neuron activity. When D is small, three fixed points arise, including two stable equilibria—one corresponding to a “healthy” (euthymic) state and the other associated with reduced mirror neuron activity (an “autistic” state). Under large D, the system supports only the euthymic fixed point, indicative of a non-susceptible population. Finally, we demonstrate that while acute reductions in stress have negligible impact on the long-term dynamics, chronic reduction of stress can restore cortisol levels and mirror neuron activity to the euthymic range. These findings suggest that chronic maternal stress can be a critical determinant in the onset of autism-like neurodevelopmental trajectories for susceptible individuals and underscore the importance of sustained stress management interventions during pregnancy.