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. Author manuscript; available in PMC: 2017 Jun 15.
Published in final edited form as: Brain Res. 2015 Dec 10;1641(Pt B):306–319. doi: 10.1016/j.brainres.2015.11.039

Figure 1.

Figure 1

MPH can be used to differentiate between distinct behavioral phenotypes that represent two ends of the spectrum of sustained attention performance. A. Distribution of performance in the sustained attention task (VI). Within the rodent population in our study, performance in the sustained attention task varies along a spectrum, from just above the threshold for chance (VI = 0.35) to near perfect performance (VI = 1.0). Animals were grouped to the next highest tenth arbitrary unit of VI in the histogram seen here to visually demonstrate the distribution of the performance of all the animals used in this study (n=25). The distribution of animals fits a Gaussian curve according to Shapiro Wilks Test for normality (W(25)= 0.948, p=0.225). The median level of performance in this set of animals was 0.634 with a mean of 0.654. B. Overall, methylphenidate at a behaviorally relevant dose (8 mg/kg, p.o.) significantly improved performance in the sustained attention task as measured by Vigilance Index (F(1,24)=7.995, p<0.01). C. Distribution of the effect of MPH (8 mg/kg, p.o.) on individual performance (VI). The change in VI of each individual rat was grouped into the next highest 0.05 bin of the arbitrary VI unit to examine the distribution of the effect of MPH. The distribution of MPH’s effect on performance as measured by change in VI following treatment with MPH (8 mg/kg, p.o.) fits a Gaussian distribution (W(25)=0.984, p=0.952). The mean response was 0.0584 and the median response was 0.0598. D. Correlation between baseline VI and VI with MPH. MPH improved sustained attention in more animals with a lower level of baseline performance than those with a higher baseline level of performance. Only 4 of 13 animals (31%) with a baseline VI above 0.65 (vertical dashed line) showed an increase in VI greater than 0.05 after MPH treatment while 9 of 13 animals (69%) with a baseline VI below 0.65 showed a MPH mediated increase in VI of 0.05 or greater. Filled circles = change in VI > 0.05; open circles = change in VI < 0.05.