Fig. 7.

Perisynaptic astroglia. 3D reconstructions from the mild (a) and moderate (b) cases show perisynaptic astroglial processes (turquoise) at the edges of synapses (PSDs, red) between dendritic spines (yellow) and presynaptic axons (green). (c) In the severe case, the astroglial processes (turquoise) hovered around the periphery of many pre-synaptic axons (multicolored), which synapses on a single multisynaptic spine (yellow). (d) Fraction of synapses with perisynaptic astroglia at the ASI is less in the severe than mild (*P < 0.05) or moderate (**P < 0.01) cases. (e) Synapses were smaller when astroglial processes were absent from the ASI (*P < 0.05). (f) Correlation between total PSD area and the length of the ASI perimeter not apposed by astroglial processes (mild, r = 0.73, P < 0.0001; moderate, r = 0.58, P < 0.0001; severe, r = 0.28, P = 0.18, data not shown). (g) The average astroglia-free distance through extracellular space to the nearest neighboring synapse was greater in moderate (0.98 ± 0.17 µm) than the mild (0.46 ± 0.05 µm) case (**P < 0.01).