Figure 4.

Effects of spontaneous alternation testing (during gray section of graph) on levels of glucose in the extracellular fluid (ECF) of the hippocampus, as measured with microdialysis procedures applied before, during, and after testing. Glucose levels remained generally constant in rats not tested on the maze (top line, blue ovals). Testing on a 4-arm alternation maze resulted in substantial and significant decreases in ECF glucose levels (bottom line, red diamonds). Testing a a 3-arm maze resulted in smaller decreases in glucose (middle line, green boxes); these values were significantly different than either controls or rats tested on the 4-arm maze. Because rats tested on the 3-arm maze had similar locomotor activity and exhibited alternation scores above baseline, the smaller decrease in glucose appears to be based on the different cognitive loads between the more-demanding 4-arm and less-demanding 3-arm mazes. (From McNay et al., 2000).