Alan J. Sokoloff
Assistant Professor of Physiology (Research)
The focus of our research is the organization of muscles of speech, feeding and respiration using anatomical, physiological, histochemical and molecular approaches in non-primate mammal, non-human primate and human models. The molecular bases of age- and disease-related dysfunction in tongue, hyoid and pharyngeal muscle systems subserving these oromotor behaviors differ by system, offering unique opportunities to identify the mechanisms of pathology.
Muscles typically lose tissue and function with aging, i.e., undergo sarcopenia, but our neuromuscular studies suggest that tongue muscles are resistant to many features of sarcopenia. We are investigating growth and atrophy related signaling pathways to understand the biological bases of preservation of tongue neuromuscular function with aging. Several features of tongue muscle organization likely influence signaling pathways that promote muscle health. (1). Tongue movements involve complex changes in tongue body shape, including extensive eccentric contraction. (2) Some tongue muscle fibers are persistently active to control the airway. (3) Tongue muscles undergo submaximal activation (i.e., during swallowing). An understanding of the biological underpinnings of dysfunction by system can enable targeted and optimized therapeutic interventions.
We are currently engaged in four areas of investigation: (1) Neuromuscular organization of tongue, hyoid and pharyngeal muscles in health, aging and disease; (2) Growth and atrophy related signaling; (3) Tongue wound repair and prosthetics and (4) Bases of oromotor dysfunction in developmental disorders.
1). Tongue, hyoid and pharyngeal muscle systems have unique activity profiles associated with phonation, respiration, and feeding and offer a functional contrast to appendicular muscles. They also differ from other skeletal muscles in their embryonic derivation from branchial arches and cranial neural crest tissue and their direct innervation by motor neurons from the brainstem. These features often result in extreme specialization of muscles, but our research to date reveals that tongue and suprahyoid muscles are more similar to conventional skeletal muscle than specialized eye and jaw muscles.
2). Because of their resistance to sarcopenia, tongue muscles offer a unique opportunity to understand signaling through pathways associated with muscle growth and atrophy. In collaboration with Dr. Thomas Burkholder at the Georgia Institute of Technology we are investigating the involvement of signaling pathways that transduce mechanical stress and muscle activity in tongue versus hyoid and pharyngeal muscles in aging and disease.
3). The tongue heals quickly, and voluntary control of tongue musculature is spared in high spinal cord injury, enabling control of assistive technologies by tongue movement. With Dr. Maysam Ghovanloo at the Georgia Institute of Technology we are investigating the histological and functional consequences of tongue implantation to determine optimization and safety of tongue implants for assistive technologies.
4). Oromotor dysfunction is common in many developmental disorders including Autism Spectrum Disorder. This dysfunction is likely related to peripheral (sensorimotor) and central aspects of oromotor system organization. We are currently developing models to understand the genesis of oromotor dysfunction in these disorders.
Publications: PubMed search
Department of Physiology