Figure 5

Variation of the imaging signal profile and depth within a single rat at each time-point after the craniotomy. (A) Fluorescent signal intensity versus cortical depth at each two week interval, between 2 and 14 weeks. The signal represents the mean signal intensity across each imaged slice, normalized to the brightest pixel’s signal intensity. Within the cranial window, two sites were selected at random for imaging, at each time-point. The data collected from these two fields-of-view were averaged to provide an estimate of signal decay with depth at that time-point. Fluorescence a.u. – arbitrary units. (B) Comparison of the cortical depth at signal intensity level of e⁻¹ of the maximum surface signal intensity and the maximum imaging depth achieved in the rat at each time-point. (• e⁻¹; ━ maximum).