Experimental pipeline, image processing, and decreasing pruning rates.

(A) Schematic of the somatotopic mapping of whiskers to neocortical columns in the mouse somatosensory cortex. (B) Tangential sections from flattened brains preserve the structure of the barrel-field, enabling easy identification and isolation of the D1 barrel in tissue from different ages. (C) A support vector machine (SVM) classifier is trained using manually labeled examples of synapses and non-synapses in electron microscopy images. (D) Example images of synapses at three different time points corresponding to peak synapse density (P19), and later drop-off (P24 and P32). Scale bar represents 500nm. (E) Developmental pruning rate (raw data, left; binned data, right). Red lines show spline interpolations of the data points. Insets show that the majority of synapses are pruned during the first half of the developmental pruning period.