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. Author manuscript; available in PMC: 2016 Mar 29.
Published in final edited form as: Science. 2015 Nov 27;350(6264):aac9462. doi: 10.1126/science.aac9462

Fig. 5. Principles of connectivity in neocortical circuits.

Fig. 5

(A) Connection probability correlates with mean synaptic strength. Plot of the mean amplitudes of uIPSPs or uEPSPs of each type of connection against the connectivity rate for each type of connection [r(96) = 0.70, P < 0.0001 for interneuron→interneuron connection; r(20) = 0.65, P = 0.001 for interneuron→pyramidal neuron connection; r(14) = 0.56, P = 0.03 or pyramidal neuron→interneuron connection]. (B) (Left) Connectivity rate from excitatory cells to MCs and NGCs. (Right) Connectivity rate from all (non-MC, non-NGC) interneurons to MCs and NGCs. (C) (Left) The self-connections of PTI occurs in 44.2% (257/582; pooling across all PTIs), whereas self-inhibition between ISIs occurs only in 3.2% (3/95) of tested connections (GLM with factor of class of interneuron (PTI vs. ISI); P < 0.0001). (Right) There is a strong positive correlation between inhibition of pyramidal neurons and self-inhibition [r(11) = 0.72; p = 0.01]. Note that origin contains three points. (D) Pyramidal cells provided input to PTIs in 14.7% (61/415; pooling across all PTIs, from L23Pyr) and 5.3% (27/505, from L5Pyr) of the tested connections, whereas pyramidal cells rarely provided input to ISIs (0.74%, 1/135; 0.0%, 0/148 for L23 and L5 pyramidal neurons, respectively; GLM with factors of class of interneuron (PTI vs. ISI) and layer of pyramidal neuron; effect of interneuron class: P = 0.005; layer: P = 0.009; interaction: P = 0.76).