Isabella Pelosi, FCLC '26

Major: Integrative Neuroscience

Bio: Hi! I am Isabella Pelosi, a senior Integrative Neuroscience student concentrating in Cellular Molecular studies, and minoring in Biological Ethics at Fordham University Lincoln Center. I am passionate about all things science-related, including; neurology, medicine, ethics, and chemistry. I am originally from Downingtown, Pennsylvania. Some of my main interests outside of my studies are dance, coffee, and cats!

Title of Research: Masseter muscle Sensory-motor circuit is affected in Spinal muscular Atrophy (SMA)

Mentor: Danny Florez Paz, Natural Science

Abstract: Spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disorder and the leading genetic cause of infant mortality. It is caused by mutations in the survival motor neuron 1 (SMN1) gene, resulting in reduced levels of SMN protein. Clinically, SMA is characterized by motor neuron (MN) degeneration, muscle weakness, and impaired motor function. Disease severity is influenced by the number of survival motor neuron 2 (SMN2) gene copies, which produce only ~10% functional SMN protein. SMA Type 1 is typically lethal within the first 6 months of life, while milder forms (Types 2 and 3) allow longer survival but are associated with feeding difficulties and reduced body weight.

The masseter muscle is essential for suckling and mastication throughout development, yet the impact of SMA on orofacial musculature remains poorly understood. We hypothesized that the sensory-motor circuit controlling masseter activity is disrupted in SMA.
Using a mouse model, SMNΔ7 +/+, this study investigated motor neuron death and synaptic impairments in the sensory motor circuit innervating the masseter muscle in postnatal day 10 (p10) mice. MN, synaptic quantification, and motor neuron cell area analysis were performed in SMNΔ7 +/+ and wild-type (WT) mice.

SMNΔ7 +/+ mice exhibited a significant reduction in motor neurons, proprioreceptive synapses, and soma area size within the trigeminal motor nucleus (MoV), which innervates the masseter muscle, compared to WT controls. These findings suggest an increase in neurodegeneration within the sensory-motor circuit innervating the masseter muscle, potentially contributing to weight loss in these animals due to masseter muscle malfunction during feeding.