Figure 2

Functional impairment of the mossy fiber pathway after 13 months of Tau ^RDΔ expression. (a) Basal synaptic transmission of mossy fibers measured by input output curves (mf-i/o) is decreased in mossy fibers of pro-aggregant (Pro, red circles) and Tau knockout (TKO, blue triangles) mice compared to control littermates (Ctrl, black squares) and anti-aggregant (Anti; green triangles) animals. (b) Paired pulse facilitation of the mossy fiber pathway (mf-ppf) is significantly impaired in pro-aggregant mice (Pro, red column) compared to control littermates (Ctrl, white column), but not changed significantly if compared to anti-aggregant (Anti, green column) and Tau knockout (TKO, blue column) mice. (c) Frequency facilitation of the mossy fiber pathway (mf-ff) is reduced ~40% in pro-aggregant animals (Pro; red circles) compared to wildtype littermate control mice (Ctrl, black squares). (d) Anti-aggregant mice (Anti, green triangles) are less dramatically affected in terms of mf-ff impairment (~30%) compared to control mice. (e) Tau depleted mice (TKO, blue triangles) show no differences in mf-ff compared to control animals (Ctrl, black squares). (f) Long-term depression (LTD) of mossy fiber field excitatory postsynaptic potential (mf-LTD) induced by low frequency stimulation is not expressed in pro-aggregant mice (Pro, red circles), whereas control littermates (Ctrl, black squares) show a synaptic depression of about −30% of baseline. (g) Mossy fiber LTD in anti-aggregant mice (Anti, green triangles) is not different from control littermates. (h) Endogenous Tau is not necessary for normal mossy fiber LTD as shown by Tau knockout mice (TKO, blue triangles). (i) mf-LTD in 2 month old mice is expressed in pro-aggregant mice (Pro, red circles) and control littermates (Ctrl, black squares). Both groups show a synaptic depression of about −30% of baseline. Error bars represent SEM. Values represent recordings from at least 5 animals per group.