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Sniff adjustment in an odor discrimination task in the rat: analytical or synthetic strategy?

Courtiol E, Lefèvre L, Garcia S, Thévenet M, Messaoudi B, Buonviso N - Front Behav Neurosci (2014)

Bottom Line: We found that sniffing variations were not only a matter of odorant sorption properties and that the same odorant was sniffed differently depending on the odor pair in which it was presented.These results suggest that rather than being adjusted analytically, sniffing is instead adjusted synthetically and depends on the pair of odorants presented during the discrimination task.Our results show that sniffing is a specific sensorimotor act that depends on complex synthetic processes.

View Article: PubMed Central - PubMed

Affiliation: Centre de Recherche en Neurosciences de Lyon, Equipe Olfaction: du codage à la mémoire, CNRS UMR 5292-INSERM U1028-Université Lyon1 Lyon, France.

ABSTRACT
A growing body of evidence suggests that sniffing is not only the mode of delivery for odorant molecules but also contributes to olfactory perception. However, the precise role of sniffing variations remains unknown. The zonation hypothesis suggests that animals use sniffing variations to optimize the deposition of odorant molecules on the most receptive areas of the olfactory epithelium (OE). Sniffing would thus depend on the physicochemical properties of odorants, particularly their sorption. Rojas-Líbano and Kay (2012) tested this hypothesis and showed that rats used different sniff strategies when they had to target a high-sorption (HS) molecule or a low-sorption (LS) molecule in a binary mixture. Which sniffing strategy is used by rats when they are confronted to discrimination between two similarly sorbent odorants remains unanswered. Particularly, is sniffing adjusted independently for each odorant according to its sorption properties (analytical processing), or is sniffing adjusted based on the pairing context (synthetic processing)? We tested these hypotheses on rats performing a two-alternative choice discrimination of odorants with similar sorption properties. We recorded sniffing in a non-invasive manner using whole-body plethysmography during the behavioral task. We found that sniffing variations were not only a matter of odorant sorption properties and that the same odorant was sniffed differently depending on the odor pair in which it was presented. These results suggest that rather than being adjusted analytically, sniffing is instead adjusted synthetically and depends on the pair of odorants presented during the discrimination task. Our results show that sniffing is a specific sensorimotor act that depends on complex synthetic processes.

No MeSH data available.


Non-invasive sniff recording. (A) Schematic representation of the whole-body plethysmography. This setup allows us to access the respiratory signal of the animal in a non-invasive manner. The plethysmograph is equipped with three ports: an odor port (pink, central) connected to the olfactometer and two reward ports (black and white circles surrounded with blue lines) equidistant from the central odor port. (B) Example of one trial. The rat starts the trial by poking its nose into the central port; this motion triggers the delivery of an odorant for 3 s (green). Each odorant was associated with a reward port: odorant A/left port and odorant B/right port. If the rat makes the correct choice, water is available at the reward port for 6 s from the beginning of the trial. The first lick (light green) triggers the delivery of 60 μL of water (blue).
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Figure 1: Non-invasive sniff recording. (A) Schematic representation of the whole-body plethysmography. This setup allows us to access the respiratory signal of the animal in a non-invasive manner. The plethysmograph is equipped with three ports: an odor port (pink, central) connected to the olfactometer and two reward ports (black and white circles surrounded with blue lines) equidistant from the central odor port. (B) Example of one trial. The rat starts the trial by poking its nose into the central port; this motion triggers the delivery of an odorant for 3 s (green). Each odorant was associated with a reward port: odorant A/left port and odorant B/right port. If the rat makes the correct choice, water is available at the reward port for 6 s from the beginning of the trial. The first lick (light green) triggers the delivery of 60 μL of water (blue).

Mentions: The recording apparatus consisted of a whole-body customized plethysmograph (diameter: 20 cm, height: 30 cm, EMKA Technologies, France; Figure 1A) placed in a homemade sound-attenuating cage (length: 60 cm, width: 60 cm, height: 70 cm). The apparatus was composed of two independent airtight chambers: the animal chamber and the reference chamber. The pressure changes that resulted from animal respiration were measured by a differential pressure transducer (Model dpt, EMKA Technologies) with one sensor in the animal chamber and another in the reference chamber. The measured signal was amplified, digitally sampled at 1 kHz and acquired with a PC using an acquisition card (MC-1608FS, Measurement Computing, USA).


Sniff adjustment in an odor discrimination task in the rat: analytical or synthetic strategy?

Courtiol E, Lefèvre L, Garcia S, Thévenet M, Messaoudi B, Buonviso N - Front Behav Neurosci (2014)

Non-invasive sniff recording. (A) Schematic representation of the whole-body plethysmography. This setup allows us to access the respiratory signal of the animal in a non-invasive manner. The plethysmograph is equipped with three ports: an odor port (pink, central) connected to the olfactometer and two reward ports (black and white circles surrounded with blue lines) equidistant from the central odor port. (B) Example of one trial. The rat starts the trial by poking its nose into the central port; this motion triggers the delivery of an odorant for 3 s (green). Each odorant was associated with a reward port: odorant A/left port and odorant B/right port. If the rat makes the correct choice, water is available at the reward port for 6 s from the beginning of the trial. The first lick (light green) triggers the delivery of 60 μL of water (blue).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4017146&req=5

Figure 1: Non-invasive sniff recording. (A) Schematic representation of the whole-body plethysmography. This setup allows us to access the respiratory signal of the animal in a non-invasive manner. The plethysmograph is equipped with three ports: an odor port (pink, central) connected to the olfactometer and two reward ports (black and white circles surrounded with blue lines) equidistant from the central odor port. (B) Example of one trial. The rat starts the trial by poking its nose into the central port; this motion triggers the delivery of an odorant for 3 s (green). Each odorant was associated with a reward port: odorant A/left port and odorant B/right port. If the rat makes the correct choice, water is available at the reward port for 6 s from the beginning of the trial. The first lick (light green) triggers the delivery of 60 μL of water (blue).
Mentions: The recording apparatus consisted of a whole-body customized plethysmograph (diameter: 20 cm, height: 30 cm, EMKA Technologies, France; Figure 1A) placed in a homemade sound-attenuating cage (length: 60 cm, width: 60 cm, height: 70 cm). The apparatus was composed of two independent airtight chambers: the animal chamber and the reference chamber. The pressure changes that resulted from animal respiration were measured by a differential pressure transducer (Model dpt, EMKA Technologies) with one sensor in the animal chamber and another in the reference chamber. The measured signal was amplified, digitally sampled at 1 kHz and acquired with a PC using an acquisition card (MC-1608FS, Measurement Computing, USA).

Bottom Line: We found that sniffing variations were not only a matter of odorant sorption properties and that the same odorant was sniffed differently depending on the odor pair in which it was presented.These results suggest that rather than being adjusted analytically, sniffing is instead adjusted synthetically and depends on the pair of odorants presented during the discrimination task.Our results show that sniffing is a specific sensorimotor act that depends on complex synthetic processes.

View Article: PubMed Central - PubMed

Affiliation: Centre de Recherche en Neurosciences de Lyon, Equipe Olfaction: du codage à la mémoire, CNRS UMR 5292-INSERM U1028-Université Lyon1 Lyon, France.

ABSTRACT
A growing body of evidence suggests that sniffing is not only the mode of delivery for odorant molecules but also contributes to olfactory perception. However, the precise role of sniffing variations remains unknown. The zonation hypothesis suggests that animals use sniffing variations to optimize the deposition of odorant molecules on the most receptive areas of the olfactory epithelium (OE). Sniffing would thus depend on the physicochemical properties of odorants, particularly their sorption. Rojas-Líbano and Kay (2012) tested this hypothesis and showed that rats used different sniff strategies when they had to target a high-sorption (HS) molecule or a low-sorption (LS) molecule in a binary mixture. Which sniffing strategy is used by rats when they are confronted to discrimination between two similarly sorbent odorants remains unanswered. Particularly, is sniffing adjusted independently for each odorant according to its sorption properties (analytical processing), or is sniffing adjusted based on the pairing context (synthetic processing)? We tested these hypotheses on rats performing a two-alternative choice discrimination of odorants with similar sorption properties. We recorded sniffing in a non-invasive manner using whole-body plethysmography during the behavioral task. We found that sniffing variations were not only a matter of odorant sorption properties and that the same odorant was sniffed differently depending on the odor pair in which it was presented. These results suggest that rather than being adjusted analytically, sniffing is instead adjusted synthetically and depends on the pair of odorants presented during the discrimination task. Our results show that sniffing is a specific sensorimotor act that depends on complex synthetic processes.

No MeSH data available.