Figure 2.

Distal network activation causes context-dependent synaptic effects. (a) Whole-cell patch clamp recordings of V_m in current clamp mode from a single neuron in the absence of visual stimulation. Responses to distal network activation are shown for 20 trials (gray) and on average (thick black). The average trace in the absence of distal network activation (control) is shown for comparison (thin black). (b) Effect of distal network activation on V_m, relative to control condition, averaged over 14 neurons. Traces show mean±s.e.m.. mV values indicate mean potential in the absence of distal network activation. (c,d) Same as a, b, in the presence of visual stimulation (100% contrast). a and c are from the same neuron. (e,f) Same as b,d, during positive (e, +50 pA) or negative (f, −223±16 pA) current injection. (g) Measurements of IPSCs in another neuron in the absence of visual stimulation, obtained in voltage clamp mode at V_hold =+20mV. Same format as in a. Gray traces show 15 individual trials. (h) Difference between activated and control traces, averaged over 10 neurons (mean±s.e.m.). (i-j) Same as g-h, but at 100% contrast. (k-n) Same as g-j measured at V_hold=−60 mV to estimate EPSCs. g,i,k,m are from the same neuron.