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Completed Project

Attention Correlates with Glutamate Recycling in Astrocytes: Using Reaction Times and Accuracy from the Sustained Attention Task to Measure Vigilance in Attending and Non-Attending Rats

Benjamin Goya ’21 and Professor Lori Newman (Psychological Science)

Astrocytes have an important role in cognition as they possess a unique function to recycle glutamate (an excitatory neurotransmitter) from synapses using the enzyme, glutamine synthetase (GS). Dysfunctional astrocytes found in neurodegenerative disorders, like Alzheimer’s disease, have decreased levels of GS correlating with cognitive impairment. We seek to understand how GS levels relate to sustained attention within male and female Long Evans rats. Using the sustained attention task (SAT) created by McGaughy & Sarter (1994), the rats are tasked with discriminating between a signal trial (500 ms, 100 ms, 25 ms) and a non-signal trial. To examine the effects of time on task, we divide each session into three blocks of trials. Based on their performance on the task we divided our samples into groups of attending (higher performance) and non-attending animals. Our SAT analysis showed a significant difference between signal lengths, with 500 ms signal trials having the fastest reaction times and the most accurate results, and 25 ms signal trials having the slowest reaction times and the least accurate results. Between the signal and the nonsignal trial, the animals demonstrated a significantly faster reaction to signal trials compared to the nonsignal trial. Our SAT analysis also showed no significant sex difference between females and males, but showed that attending animals respond significantly faster than non-attending animals. There was a significant effect of task progression on attention, with accuracy of correct hits decreasing as the blocks increased. This demonstrates that the animals experienced a vigilance decrement as time progressed. Our data highlights the relationship between the reaction times of the SAT and attention.  Additionally using immunohistochemistry for GS, we observed significantly higher levels of GS present in the prefrontal cortex and hippocampus of attending animals compared to non-attending animals. Thus we can further connect our understanding of attention to GS recycling. By understanding this connection between astrocytes and cognitive function, we can design therapeutic targets for patients suffering from disorders.