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. 2015 Dec 10;4:e09460. doi: 10.7554/eLife.09460

Figure 6. Memory deficits arise from misaligned feeding in mice.

(a) Recall of the fear conditioned (FC) context is measured by the percentage of freezing when re-exposed to the fearful context. Misaligned mice (n = 8) show significant deficits in recall of contextual (FC) compared to aligned mice (n = 8;***p < 0.001) when trained and tested during the day (ZT 2). Circadian regulation of learning and memory is demonstrated by the decreased recall in aligned mice trained and tested at night (ZT 14; n = 8; #p < 0.001). This time of day effect is lost in misaligned mice (n = 8), which perform equally poorly at both times. (b) Novel object recognition (NOR) is reported using a discrimination index of Tnovel/(Tnovel+Tfamiliar), and mice are considered to exhibit NOR at values of 0.5 and above (dotted red line). NOR is impaired in misaligned mice trained and tested at night (ZT 21; n = 8) compared to aligned mice (n = 8; ***p < 0.001). Time of day effects were also found for NOR in aligned mice (n = 8; #p < 0.01), which perform better during the night than day (ZT 9). Misaligned mice fail to show a time of day effect (n = 7), again showing equally poor performance at both times. Box and whisker plots display the median as a line, the 25th to 75th percentiles, and the 10th to 90th percentiles respectively.

DOI: http://dx.doi.org/10.7554/eLife.09460.015

Figure 6—source data 1. Performance on long term memory tests in mice subjected to aligned and misaligned feeding.
DOI: http://dx.doi.org/10.7554/eLife.09460.016
elife-09460-fig6-data1.xls (30.5KB, xls)
DOI: 10.7554/eLife.09460.016

Figure 6.

Figure 6—figure supplement 1. Acquisition of FC freezing in the day (ZT 2, n = 8/group) and night (ZT 14; n = 8/group) are unaltered by misaligned feeding.

Figure 6—figure supplement 1.

(a) Misaligned mice did not show significant changes in baseline freezing (p = 0.3), freezing in response to the first foot shock (US-1; p = 0.9), or freezing in response to the second foot shock (US-2; p = 0.1). Recall was significantly reduced in misaligned mice as reported in the main text and Figure 6. (b) Misaligned feeding did not cause differences in baseline freezing (p = 1.0), nor in acquisition of freezing in response to US-1 (p = 0.9) and US-2 (p = 0.5). There was a time of day effect on freezing in response to US-2 (#p < 0.05), as previously reported (2).
DOI: http://dx.doi.org/10.7554/eLife.09460.017