Figure 6.

Rats sniff actively when going forward toward the odor compartment. a, Scatter of sniff rate in forward path versus return path averaged over the entire dataset, all rats. Line is for equal rates. Forward rate is almost always faster than return. b, Sniff rate for direct and serial trials is the same. Each point is mean of rate in serial trials versus direct trials for a given rat on a given day. Line is for equal rates. c, Average sniff rate plotted against average running speeds. Blue dots are forward direction and red dots are return. These form distinct clusters. Forward sniff is faster, and run is slower, than return.