Due to these variations in layer-dependent microvascular density, it can be challenging to interpret single-condition layer-profiles without reference conditions. This challenge can be mitigated by introducing the control- analysis steps described in the section shared sources of signal fluctuations. Alternatively, this bias can be mitigated by explicitly measuring the layer-dependent vascular reactivity, e.g. by means of gas calibrations, by means of resting-state, or by means of the residuals of the task design (Guidi et al. 2017; 2020).
