Digitized Honors Theses (2002-2017)

Date of Award

5-2003

Document Type

Undergraduate Thesis

Degree Name

BS

Department

Biomedical Sciences

Faculty Mentor

Cindy Stanfield, Ph.D.

Advisor(s)

Julio Turrens, Ph.D., Brad Davis, Ph.D.

Abstract

ON and OFF cells located in the rostral ventral medullar are currently hypothesized to inhibit and facilitate nociception, respectively. ON cells are thought to begin firing about half a second before the withdrawal reflex occurs, independent of stimulus intensity. Other research studying ON cells has categorized them using two separate methods, background activity or action potential characteristics. ON cells characterized by a regular pattern of background activity are considered "regular" ON cells, while ON cells that are relatively quiet are "silent" ON cells. ON cells can also be classified as fast spike or slow spike ON cells. Fast spike ON cells have a fast rate of depolarization and a shorter duration action potentials than slow spike ON cells. Fast spike ON cells also respond to noxious stimuli nearly twice as fast as slow spike ON ce11s. Eight ON cells were isolated for study and, based on the background activity, categorized as a "regular" ON cell with a regular pattern of background activity or as a "silent" ON cell without much background activity. Of the 8 ON cells, 4 were "regular'' ON cells and 4 were "silent" ON cells. The cumulative sum of the neural counts was measured and graphed, and the onset of neural activity prior to the tail flick was determined from the graphs. All 4 of the "regular" ON cells responded about 3 seconds before the tail flick occurred, twice as fast as the "silent" ON cells that responded about 1.5 seconds before the tail flicked. Based on these data, it can be concluded that "regular" ON cells and fast spike ON cells are two different names for the same subpopulation. "Silent" ON cells and slow spike ON cells together comprise a separate subpopulation of ON cells.

Download

Share

COinS