Fig. 3: Dynamics of neuronal cell turnover in the human amygdala.

Mathematical modelling of different neuronal cell turnover scenarios. a Scenario A assumes a constant turnover rate of neurons in the human amygdala over the lifetime of the individual. Fitting all samples to the model results in a median turnover rate of 0.2%/year [0.02;1.35]. However, separate fits for each sample revealed a negative correlation between age and individual turnover rate (r = −0.9, p = 0.083) with an annual decline in turnover of −0.03%/year. Green dots are amygdala measurements from both hemispheres from the same individual. Mean of these two dots are shown as black dot in between. b Scenario LIN, assuming a linear decline in cell turnover with age, revealed a median annual change in turnover rate (black vertical line) of −1 %/year [−4;0.08]. c Markov-Chain-Monte Carlo sampling for neuronal turnover for scenario 2POP, which assumes a quiescent and a renewing neuronal population, showing a two-dimensional marginal posterior distribution for turnover rate and fraction of renewing cells; blue: low probability, yellow: high probability, 1-sigma confidence region is framed by a red line. d Marginal posterior distribution for the estimated turnover rate calculated to the entire neuronal population, which is the product of the renewing rate of the renewing fraction, and the fraction of renewing cells, based on scenario POP2. Vertical red lines indicate lower and upper estimates (one sigma) of neuronal turnover. Black vertical line indicates median of turnover. e Age of amygdaloid neurons in relation to subject age based on the lower turnover limit of scenario 2POP. The bisecting (dashed) line represents a no-turnover-scenario in which every cell is as old as the individual, the blue line progressively deflects from the bisector with increasing subject age, reflecting lifelong post-natal neuronal cell turnover.