Fig 3.

Effect of caffeine on the expression of conditioned freezing: (a) Pre-CS freezing and freezing to the tone CS is expressed across successive 2-min bin. The histogram on the right illustrates the mean freezing level per 2-min bin of the 8-min CS period. (b) Freezing to the training context 24 h after the CS-test is expressed in 2-min bins on the left and averaged across the four bins in the histogram on the right. Caffeine significantly impaired the expression of conditioned tone freezing and context freezing irrespective of the time of administration (i.e. before conditioning, before testing, or before both stages. * denotes that the V-V group froze significantly more than all other groups (p < 0.05) based on Dunnett's post-hoc tests. V-V: vehicle-vehicle (n = 8), V-C: vehicle-caffeine (n = 7), C-V: caffeine-vehicle (n = 7), V-V: caffeine-caffeine (n = 8).