Fig. 2.

Acetylcholine increases the signal amplitude while leaving the noise amplitude intact. (Top) Signal and noise amplitudes of the response of neurons in the visual cortex to naturalistic movie sequences, under cholinergic stimulation (ACh) or control (Cont.) conditions. Example taken from a representative bin size corresponding to the vertical bar shown at the Bottom. (Bottom) Percent difference of signal and noise amplitudes in the ACh vs. control conditions for various bin sizes, depicted is the median. Cholinergic activity significantly increases signal amplitudes (sign test, P < 0.001).