Fig. 9.
Obstructions to diffusion in the synaptic cleft increase synaptic independence. Possible submicroscopic obstacles to diffusion within the synaptic cleft were modeled by setting the volume fraction and tortuosity of the synaptic cleft to the following pairs of values: αcleft = 1, λcleft = 1 (ctrl, unimpeded diffusion); αcleft = 0.7, λcleft = 1.3; αcleft = 0.3, λcleft = 1.7; αcleft = 0.1, λcleft = 1.9. Increased synaptic AMPA (A), and NMDA (B) responses are observed as α is decreased and λ is increased, but spillover responses (500 nm; C, D) are unchanged.