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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.


Sniffing signal processing. (A) Top: Raw sniffing signal recorded by the plethysmograph. An algorithm was applied to detect the zero-crossing points. Bottom: The blue squares represent the detection of the beginning of the inspiratory phase, and the violet squares represent the beginning of the expiratory phase. (B1) Sampling duration and number of sniffs. Sampling duration (Sd) is defined as the time spent in the odor port. The number of sniffs (Ns) is defined as the number of sniffs occurring during the sampling period (pink square). (B2) A representative sniff cycle is shown to illustrate the parameters measured: inspiration duration (ID), expiration duration (ED), and inspiration peak flow rate (IPF).
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Figure 2: Sniffing signal processing. (A) Top: Raw sniffing signal recorded by the plethysmograph. An algorithm was applied to detect the zero-crossing points. Bottom: The blue squares represent the detection of the beginning of the inspiratory phase, and the violet squares represent the beginning of the expiratory phase. (B1) Sampling duration and number of sniffs. Sampling duration (Sd) is defined as the time spent in the odor port. The number of sniffs (Ns) is defined as the number of sniffs occurring during the sampling period (pink square). (B2) A representative sniff cycle is shown to illustrate the parameters measured: inspiration duration (ID), expiration duration (ED), and inspiration peak flow rate (IPF).

Mentions: Using the whole-body plethysmography setup, the natural respiratory signal was a periodic function showing alternating negative (inspiration) and positive (expiration) deflections (Figure 2A). A key aspect of respiratory signal analysis was the detection of these deflections to measure respiratory cycles, which was achieved using an algorithm described in Roux et al. (2006). The algorithm performed signal smoothing for noise reduction and detection of zero-crossing points to accurately define the inspiration and expiration phases. The inspiration phase started at the zero-crossing point of the falling phase and ended at the zero-crossing point of the rising phase. The expiration phase started at the zero-crossing point of the rising phase and ended at the zero-crossing point of the falling phase (Figure 2A). In addition, to eliminate detection artifacts, we determined a cut-off value for signal duration (rejection if value < median/4) and for signal amplitude (rejection if value < median/6).


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)

Sniffing signal processing. (A) Top: Raw sniffing signal recorded by the plethysmograph. An algorithm was applied to detect the zero-crossing points. Bottom: The blue squares represent the detection of the beginning of the inspiratory phase, and the violet squares represent the beginning of the expiratory phase. (B1) Sampling duration and number of sniffs. Sampling duration (Sd) is defined as the time spent in the odor port. The number of sniffs (Ns) is defined as the number of sniffs occurring during the sampling period (pink square). (B2) A representative sniff cycle is shown to illustrate the parameters measured: inspiration duration (ID), expiration duration (ED), and inspiration peak flow rate (IPF).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4017146&req=5

Figure 2: Sniffing signal processing. (A) Top: Raw sniffing signal recorded by the plethysmograph. An algorithm was applied to detect the zero-crossing points. Bottom: The blue squares represent the detection of the beginning of the inspiratory phase, and the violet squares represent the beginning of the expiratory phase. (B1) Sampling duration and number of sniffs. Sampling duration (Sd) is defined as the time spent in the odor port. The number of sniffs (Ns) is defined as the number of sniffs occurring during the sampling period (pink square). (B2) A representative sniff cycle is shown to illustrate the parameters measured: inspiration duration (ID), expiration duration (ED), and inspiration peak flow rate (IPF).
Mentions: Using the whole-body plethysmography setup, the natural respiratory signal was a periodic function showing alternating negative (inspiration) and positive (expiration) deflections (Figure 2A). A key aspect of respiratory signal analysis was the detection of these deflections to measure respiratory cycles, which was achieved using an algorithm described in Roux et al. (2006). The algorithm performed signal smoothing for noise reduction and detection of zero-crossing points to accurately define the inspiration and expiration phases. The inspiration phase started at the zero-crossing point of the falling phase and ended at the zero-crossing point of the rising phase. The expiration phase started at the zero-crossing point of the rising phase and ended at the zero-crossing point of the falling phase (Figure 2A). In addition, to eliminate detection artifacts, we determined a cut-off value for signal duration (rejection if value < median/4) and for signal amplitude (rejection if value < median/6).

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.