PMC

Relationship between right diaphragm sniff TM motion and sniff nasal pressure in patients (A), and the relationship between left diaphragm sniff TM motion and sniff nasal pressure in patients (B). TM = time movement; Sniff TM mode = Sniff TM motion.

Sniff TDI peak inspi = sniff peak diaphragm tissue Doppler imaging velocity.

Variability in sniffing strategies during odor discriminations. A: sniff frequency plots of individual rats (n = 7) performing the lick/no-lick 2-odor discrimination. Traces represent the average of 4 behavioral sessions per rat at >80% correct response accuracy, plotted as in . These traces include data from the 3 rats shown in . At right are peak sniff frequencies during odor sampling and lick latencies for each rat. Peak sniff frequencies were determined from each animal's average sniff trace. Median lick latencies relative to odorant onset were calculated from CS+ trials. There was a strong relationship between sniff frequency and lick latencies. B: sniff count histograms and sample sniff traces from rat 5 (top) and rat 6 (bottom) during odor discrimination. Rat 6 frequently showed a rapid sniff bout on odor presentation, whereas rat 5 maintained resting sniff frequencies. C: sniff amplitude plots for rats 5 and 6 during the odor discrimination. Peak inhalation amplitudes for each sniff were placed in 100-ms time bins and averaged across all trials in a given session. Amplitude data were z-normalized before averaging. Each plot shows data from 1 session (∼100 trials) from each rat. Rat 5 shows a slight decrease in sniff amplitude for the duration of odorant presentation, whereas rat 6 shows a larger, brief decrease corresponding to the bout of high-frequency sniffing. D: sniff frequency traces averaged across all 7 rats plotted separately for CS+ (rewarded odorant, solid line) and CS− (nonrewarded odorant, dashed line) trials. Cumulative lick probability (from CS− trials) relative to the time of odorant onset is also shown. Sniff frequency, on average, diverges after the time of licking for the reward.

A. Connections for the artificial sniff apparatus. The trachea and sniff pressure sensor are connected, via a Y-connector, to the NC port of a 3-way solenoid. The vacuum line is connected to the COMM port. Control software is used to drive the switching of the solenoid such that each sniff signal opens the NC port, making a temporary connection with the vacuum line and creating the negative pressure “sniff.” B. Schematics of sniff traces. A suitable sniff trace is shown at top, while a poor trace (showing a clog) is represented on the bottom.