The Habituation/Cross-Habituation Test Revisited: Guidance from Sniffing and Video Tracking

Figure 10

Exploration times at targeted criterion thresholds. Top: exploration time (as fraction of total trial time) was established for nose to odor source distance (, <1, <2, <4, and <8 cm), head angle to odor source (, <5, <10, <20, and <40°), and velocity (, >4, >2, >1, and >0.5 cm/s) criteria at four threshold levels using population vectors (top) for S1 trials in WT mice (). Marked () is 2 (distance < 2 cm) as standard criterion reference, yielding 11% (13.2 sec) exploration time. Relaxed criteria yield higher exploration times. Bottom: the effects of head angle and velocity criteria, separately (a5–a40, v4–v0.5) or combined (a5–a40 combined with v0.5) on exploration time using a nose to odor source distance <1, <2, or <4 cm (d1–d4) as additional criterion in each graph. Marked (, black) is the combined criterion and  cm, being the commonly used “standard” criterion, which did not restrict the exploration time over criterion  cm alone (d2, Top). Also marked (, red) is the combination  cm and  cm (d4-v0.5), suggested as useful new criterion (see Results and Figure 11) that yielded 15% exploration time.