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Stephanie Alfonso, PhD

Literature Researcher

Stephanie Alfonso, PhD

Dr. Stephanie Alfonso was raised in a small Mexican border town and was schooled on both sides of the border. She moved to La Jolla to start her undergrad at UCSD; however, she was not an ordinary college freshman, she was an eighteen year old single mother. To her, a career in science translated to a life of perpetual learning and training. Stephanie wanted to pursue a career with rewarding and challenging questions that would set an example for her son of perseverance and the fulfillment of hopes and dreams.

The summer before her sophomore year, she began as a research assistant in Dr. Andrea Chiba’s lab. Her first project dealt with the corticopetal cholinergic system and its effect on cortical plasticity. To assess the role of cholinergic input to a specific sensory area, she examined the learning capacity of rats whose visual cortex was pharmacologically depleted of cholinergic input. Although rats with cholinergic deafferentation in visual cortex learned the task, their discrimination abilities were impaired when compared to controls.

For her Senior Honors’ Thesis, she wanted to examine the importance of emotional salience in memory. Her project integrated behavior with advanced molecular biology techniques. Under the guidance of Andrea Chiba and Fred H. Gage of the Salk Institute, they looked at the amygdala, a structure involved in emotions and fear-based learning, and adult neurogenesis, specifically, the birth of new neurons in the hippocampus of the adult brain. These new cells are added to an existing network of dentate gyrus neurons and are important for learning and memory. Rats were allowed limited exposure to an enriched environment during temporary inactivation of the basolateral amygdalar nucleus in order to assess the role of the amygdala in mediating the enhanced survival of new neurons due to these manipulations.

As a graduate student, she investigated the mechanism of amyloid-β (Aβ)- induced synaptic depression. Cells over-expressing Aβ and nearby control cells were recorded from using patch clamp techniques to measure their excitatory currents. They found that AMPA receptors are preferentially removed from the synapse in the presence of Aβ. Stephanie tested a proprietary compound designed to block the PDZ domain of PICK1 and found it to prevent AMPA receptor endocytosis and reverse the depressive effects of Aβ on synapses using paired patch clamp techniques and surface immunohistochemistry  (Alfonso et al 2014). She also studied a pathway in which PKCα interacts with

PICK1 by promoting its localization to the membrane. She tested a mutant  PKCα that can no longer interact with PICK1 by using patch clamp techniques and found this blocked the Aβ-induced depression. She then virally reintroduced wild-type PKCα into PKCα KO tissue and found this rescued Aβ-induced depression (Alfonso et al 2016).

Her journey has also traversed paths outside of the lab. As a volunteer with the UCSD Neuroscience Outreach Program, she learned the importance of improving public scientific literacy and continues to be active in this field.

Stephanie is now an instructor of record for the Biology and Cognitive Science departments at UCSD and her career goal is to become a full time teaching professor.