In 13 mice, new spine groups showed no clear added match to lost calcium tuning over final spine groups with the same count

We tested whether new dendritic spine groups replace the visual tuning of lost groups in the same imaged segment. We used repeated calcium responses and structural tracking from mouse visual cortex during development. The primary sample had 112 segment intervals from 22 cells in 13 mice, with 495 lost and 466 new spine interval records. A fixed reference selected the same number of spines from each final segment. Its exact expected response controlled the final local population and the new spine count. The added match to lost tuning was -0.0000467 source noise SD squared. Its 95% whole-mouse bootstrap range was -0.000199 to 0.0000981. The upper-tail score from 9,999 conditional label assignments was 0.782. An activity-group reference gave an added match of -0.00000832. Products of separate repeats gave lost and new group energies of 0.000825 and 0.000590, with pointwise ranges above zero under independent repeat errors. Thus, both groups carried visual tuning, but this test found no clear formation-specific match. Accepted trials changed the estimate, and removal of one mouse could change its sign. The result does not prove absence of functional replacement. It concerns a count-normalized sum of calcium responses, not synaptic current. The package preserves source extraction, provenance, data, code, exact reference checks, figures and repeat instructions.

dendritic spines · structural turnover · visual cortex · calcium imaging · functional replacement · repeated measurements