Fig 1.

The experimental set up (A), aversive stimulus employed (B) and the recording session timeline (C) are shown. Note that a flat panel LCD computer monitor was placed above the test tank facing down and this screen could present a moving black filled bird silhouette on a constant white background (shown on panel B). The recording session consisted of a 5 min pre-stimulus period during which no stimulus was shown, a 3 min stimulus period (during which the “bird flew” above the tank once in every 5 sec) and a 4 min post-stimulus period.