Figure 2

Effect of anandamide (AEA) on the activity of inferior colliculus (IC) neurons. (A) Typical recording of an IC neuron under an oddball stimulation paradigm before (control), during (AEA) and after (recovery) an i.v. application of AEA. (For this neuron, the standard frequency was 2105 Hz and the deviant frequency was 1724 Hz.) Application of AEA decreased the CSI from 0.58 to 0.28. For this and subsequent figures, the gray horizontal bars indicate the duration of sound stimulation and asterisks indicate a P-value less than 0.05. The insets are PSTHs that represent the mean response to the oddball sequence, in all conditions showing a significantly larger neuronal response to the deviant tone (red) than to the standard (blue). (B) Scatter plot of the CSI in control condition versus drug application. It can be seen that the CSI of most neurons decreases. (C) Bootstrapping analysis for each neuron. White dots indicate the control CSI and stars indicate the AEA application (purple stars: significant change; white stars: no change). (D) Bars represent the average value ± SE of the change for the population that had significant changes in the CSI. (E) Scatter plot of the spike count in the control condition versus AEA application for standard (blue dots) and deviant (red dots) stimuli. (F) Percent change in the responses to deviant and standard stimuli (vertical bars represent the % change ± SE). The AEA significantly increases the response to the standard stimulus. (G) Time course of adaptation for the mean response to the standard frequency for each position (time) in the oddball sequence of neurons significantly affected by anandamide. The baseline (gray circles) and anandamide data (orange circles) had fast and slow decay components and a steady-state component that were fitted by a double exponential function (black lines).