Figure 3.

Cu Isotope Mass Balance between CSF and Brain

Calculation of the Cu isotopic offset in the CSF (Δδ⁶⁵Cu_CSF) that results from the incorporation of Cu in the brain (% of exchanged Cu) associated with an isotopic fractionation Δδ⁶⁵Cu_B. The calculations are made with two values of Δδ⁶⁵Cu_B (0.5‰ in red and 0.05‰ in blue) and two extreme values of the M_B/M_CSF ratio. The results thus define two areas in red and blue that overlap giving the dark blue area. The results discussed in the text corresponding to some proportions of exchanged Cu for a Δδ⁶⁵Cu_CSF value of 0.2‰, which represents the difference between CTRL and ALS δ⁶⁵Cu mean values, are illustrated.