Figure 1.

Deficits in nest building behavior of Prnp0/0 mice. (A) The nest building behavior of WT (1) and Prnp0/0 mice (2) was assayed by assessing the nest quality after overnight exposure to a sheet of tissue paper. (B) Comparing the nest quality, statistically significant differences were obtained between WT and Prnp0/0 mice independent of their age. Values are depicted as mean ± SEM (n = 6). The quality of the nests was evaluated using a modified 5-point scale according to method of Deacon et al.³⁹ Tissue not noticeably touched (>90 % intact, 1 point); tissue partially shredded (50–90% remained intact, 2 points); mostly shredded but not identifiable as a nest (>50 % of the tissue is shredded, 3 points), an almost intact nest (>90 % of the tissue is shredded, 4 points); an intact nest (100% of the tissue is shredded, 5 points).