1. Volume 27, Issue 10, Pages 1542-1548.e4 (May 2017)
Spontaneous Rapid Odor Source Localization Behavior Requires Interhemispheric Communication 
José Esquivelzeta Rabell, Kadir Mutlu, João Noutel, Pamela Martin del Olmo, Sebastian Haesler 
Current Biology 
Volume 27, Issue 10, Pages e4 (May 2017)
DOI: /j.cub
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2. Current Biology 2017 27, 1542-1548.e4DOI: (10.1016/j.cub.2017.04.027)
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3. Figure 1 Nasal Thermography for Measuring Sniffing Dynamics
(A) Behavioral setup.
(B) Video frames at different times during the sniff cycle. Inhalation and exhalation appear as cooling (dark) and warming (light) of the intranasal surface, respectively.
(C) Example respiratory signal measured simultaneously through an implanted cannula (black) and by IR thermography (green).
(D) Example respiratory signal measured with IR thermography (green) in an anesthetized mouse.
(E) Example respiratory signal waveform obtained by IR thermography (upward and downward arrowheads indicate inhalation onset and offset, respectively; gray bars indicate inhalation time). Following the conventions in respiration research, the signal was inverted compared to (C) and (D), and so inhalation is upward.
(F) Inhalation onsets (n = 1,475) measured by intranasal pressure and IR thermography in 29 trials from two mice (Pearson’s correlation coefficient > 0.99).
(G) Distribution of respiration rates measured through an implanted cannula (top) and IR thermography (bottom). Solid lines indicate corresponding probability density functions.
(H) Timing of inhalation detection. The inhalation time of each breathing cycle measured by IR thermography was subtracted from the respective inhalation time measured by intranasal pressure. The difference between the two measurements shows variability but no consistent lag across respiration frequencies (median difference 3 ms ± SD 96 ms).
See also Figure S1.
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4. Figure 2 Odor Source Localization in a Single Sniff
(A) Examples of spatial orienting responses to novel (dark purple; filled and open circles indicate left and right odor trials, respectively) and familiar (light purple, no circles) stimuli in five different mice. Dashed lines indicates odor onset; light gray bars indicate the first sniff cycle after odor onset; chemical structures of novel stimuli are shown.
(B) Significant orienting to novel (dark purple), but not familiar (light purple), stimuli. Rightward responses are inverted such that displacement toward novel smells is always positive whereas displacement away from it is negative (mean ± SEM, n = 11 animals, repeated-measures ANOVA, novel versus familiar, F1,14 = 15.72, p = 0.001).
(C) Significant displacement from the origin in the first and subsequent sniffs after stimulation with novel (dark purple), but not familiar (light purple), stimuli (Student’s t test; displacement at each sniff cycle versus the pre-odor mean; horizontal dashed line indicates Bonferroni-corrected significance level, α = 0.003).
(D) Novel (dark green), but not familiar (light green), odorants trigger exploratory sniffing, as described previously.
(E) Both sniffing (green) and directional responses (purple) habituate concurrently with subsequent odor presentations. Error bars represent the SEM.
See also Figure S2 and Movies S1, S2, and S3.
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5. Figure 3 Involvement of the AC and AON in Nasal Orienting
(A) Illustration of the AON in olfactory circuits (OB, olfactory bulb; PCx, piriform cortex; AON, anterior olfactory nucleus; AC, anterior commissure).
(B) Transection of the AC eliminates nasal orienting to novel smells (pink; n = 5) but sham control surgery (purple; n = 6) does not (repeated-measures ANOVA, AC-lesioned versus sham control, F1,14 = 51.82, p = ).
(C) There was no difference in the sniffing response between AC-lesioned (pink) and sham control (green) animals (repeated-measures ANOVA, AC-lesioned versus sham control, F1,14 = 0.53, p = 0.49).
(D and E) Unilateral AON lesions reverse orienting to ipsilateral (D), but not contralateral (E) stimulation (pink; n = 9; mean displacement pre- versus post-odorant stimulation, contralateral t8 = 2.04, p = 0.05, ipsilateral t8 = −2.28, p = 0.05; shading indicates ±SEM). Sham-lesioned control animals correctly responded to both sides (purple; n = 7; mean displacement pre- versus post-odorant stimulation, contralateral t6 = 3.50, p = 0.006, ipsilateral t6 = 5.73, p = 6.12e-04; shading indicates ±SEM).
(F) Novel stimuli elicit exploratory sniffing in animals with unilateral AON lesions (pink; mean sniff rate ± SEM, n = 9 mice, Student’s t test, mean sniff rate pre- versus post-odorant stimulation, t8 = 12.15, p = 9.75e-07) and sham controls (green; n = 7, mean sniff rate pre- versus post-odorant stimulation, t6 = 9.67, p = 3.51e-05; shading indicates ±SEM), although with slightly different temporal profile and magnitude (repeated-measures ANOVA, AON-lesioned versus sham control, F1,14 = 4.46, p = 0.05).
See also Figure S3.
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6. Figure 4 Unilateral Activation of the AON Triggers Orienting
(A) Confocal tile scan of the brain of an experimental animal at the level of the AON. Expression of ChR2 (red) and fluorescent Nissl stain (green). The dashed area marks the zone magnified (top right). Bottom right: anatomical subdivisions of the AON (AOM, AOV, AOL, and AOD, medial, ventral, lateral, and dorsal AON, respectively; ac, anterior commissure; AOE, AON pars externa).
(B) Unilateral optogenetic AON activation triggers directional nostril movements in ChR2-expressing animals (pink; n = 9 mice, mean displacement pre- versus post-optogenetic stimulation, t8 = 1.88, p = 0.05; shading indicates ±SEM), but not control animals expressing mCherry (purple; n = 6 mice, mean displacement pre- versus post-optogenetic stimulation, t5 = −0.62, p = 0.72; shading indicates ±SEM).
(C) Unilateral optogenetic AON activation also elicits exploratory sniffing (pink; mean sniff rate pre- versus post-optogenetic stimulation, ChR2, t8 = 3.86, p = 0.02; shading indicates ±SEM). No significant sniffing response in control animals expressing mCherry but not ChR2 (green; mean sniff rate pre- versus post-optogenetic stimulation, t5 = 0.71, p = 0.25).
See also Figure S4.
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