Mixture discrimination training induces durable and generalizable olfactory learning independent of odorant structure and concentration
- State Key Laboratory of Cognitive Science and Mental Health, Institute of Psychology, Chinese Academy of Sciences, China
- Department of Psychology, University of Chinese Academy of Sciences, China
- School of Artificial Intelligence, University of Chinese Academy of Sciences, China
Figures
Figure 1 with 2 supplements
Experiment 1: distinct patterns of specificity and transfer in mixture and enantiomer discrimination learning.
(A) Schematic illustration of the experimental procedure, consisting of three phases: baseline (Day 0), unilateral olfactory training (Day 1 to Day N), and post-training testing (Day N, N+1, N+3, N+7, and N+14). Participants were assigned to one of two groups: the mixture group (n = 12), trained and tested with binary odor mixtures, or the enantiomer group (n = 12), trained and tested with odor enantiomers. Each participant trained with a designated nostril (trained nostril) and a specific odor pair (training pair). (B) Chemical structures of the olfactory stimuli. Top: constituents of two binary odor mixture pairs; bottom: two enantiomer pairs. (C) Improvements in mixture discrimination (red) and enantiomer discrimination (green) over the course of training. Data points were interpolated (gridded interpolation) and averaged across participants; squares indicate mean discrimination accuracies for the training pair in the trained nostril at baseline and at the Day N post-training test. (D) Discrimination accuracies at baseline (Day 0, lighter bars) and at the Day N post-training test (darker bars) for the training pair (red and green bars) and the control pair (brown and blue bars), presented to the trained (solid bars) and untrained (striped bars) nostrils in the mixture group (top) and enantiomer group (bottom). Gray lines represent individual participants. (E) Discrimination accuracies across post-training test sessions for the training and control pairs, presented to the trained and untrained nostrils in the mixture group (top) and enantiomer group (bottom). Black dashed lines: chance level (1/3). Shaded areas and error bars: SEMs. **p < 0.01, ***p ≤ 0.001.
Figure 1—figure supplement 1
Odor evaluations of guaiacol, eugenol, 2-butanol, and 2-heptanol by a panel of 24 participants.
(A) Intensity and valence ratings of each compound on 7-point Likert scales (7 = extremely intense/pleasant). (B) Average pairwise odor similarity ratings for structurally similar compounds (both phenols or both aliphatic alcohols) and structurally dissimilar compounds (one phenol and one aliphatic alcohol), assessed on a 7-point Likert scale (7 = extremely similar). Gray lines: individual participants. Error bars: SEMs.
Figure 1—figure supplement 2
Experiment 1: training-related olfactory adaptation and recovery.
(A) Odor intensity ratings at baseline (Day 0, lighter bars) and at the Day N post-training test (darker bars) for the training pair (red and green bars) and the control pair (brown and blue bars), presented to the trained nostril (TN, solid bars) and the untrained nostril (UN, striped bars) in the mixture group (top, n = 12) and the enantiomer group (bottom, n = 12). (B) Trajectories of odor intensity ratings for the training and control pairs presented to the trained and untrained nostrils across post-training test sessions (Day N, N+1, N+3, N+7, and N+14), averaged across participants who provided intensity ratings in all sessions (n = 13). Gray lines: individual participants. Error bars: SEMs. **p < 0.01, ***p ≤ 0.001.
Figure 2 with 2 supplements
Experiment 2: replication and extension of long-term transfer and generalization of mixture discrimination learning.
(A) Chemical structures of the constituents of two new binary odor mixture pairs used in Experiment 2. (B) Discrimination accuracies at baseline (Day 0, lighter bars) and at the Day N post-training test (darker bars) for the training pair (red bars) and the control pair (brown bars), presented to the trained (solid bars) and untrained (striped bars) nostrils. Gray lines represent individual participants (n = 12). (C) Discrimination accuracies across post-training test sessions (Day N, N+1, N+3, N+7, and N+14) for the training and control pairs, presented to the trained and untrained nostrils. Black dashed lines: chance level (1/3). Error bars: SEMs. ***p ≤ 0.001.
Figure 2—figure supplement 1
Odor evaluations of acetophenone, 2-octanone, methyl salicylate, and isoamyl butyrate by a new panel of 24 participants.
(A) Intensity and valence ratings of each compound on 7-point Likert scales (7 = extremely intense/pleasant). (B) Average pairwise odor similarity ratings for compounds within the same functional group (both ketones or both esters) and across different functional groups (one ketone and one ester), assessed on a 7-point Likert scale (7 = extremely similar). Gray lines: individual participants. Error bars: SEMs.
Figure 2—figure supplement 2
Experiment 2: training-related olfactory adaptation and recovery.
(A) Odor intensity ratings at baseline (Day 0, lighter bars) and at the Day N post-training test (darker bars) for the training pair (red bars) and the control pair (brown bars), presented to the trained nostril (TN, solid bars) and the untrained nostril (UN, striped bars). Gray lines: individual participants (n = 12). (B) Trajectories of odor intensity ratings for the training and control pairs of odor mixtures presented to the trained and untrained nostrils across post-training test sessions (Day N, N+1, N+3, N+7, and N+14). Error bars: SEMs. *p < 0.05, **p < 0.01.
Figure 3 with 1 supplement
Experiment 3: specificity and transience of concentration discrimination learning.
(A) Chemical structures of the single-compound solutes used for the training and control solutions in Experiment 3. (B) Improvements in concentration discrimination over the course of training. Data points were interpolated (gridded interpolation) and averaged across participants (n = 12); squares indicate mean discrimination accuracies for the training pair in the trained nostril at baseline and at the Day N post-training test. (C) Concentration discrimination accuracies at baseline (Day 0, lighter bars) and at the Day N post-training test (darker bars) for the training pair (purple bars) and the control pair (gray bars), presented to the trained (solid bars) and untrained (striped bars) nostrils. Gray lines represent individual participants. (D) Concentration discrimination accuracies across post-training test sessions (Day N, N+1, N+3, N+7, and N+14) for the training and control pairs, presented to the trained and untrained nostrils. Black dashed lines: chance level (1/3). Error bars: SEMs. **p < 0.01.
Figure 3—figure supplement 1
Experiment 3: concentration discrimination and training-related olfactory adaptation and recovery.
(A) Learning curve for concentration discrimination (purple, Experiment 3, n = 12), compared with mixture discrimination (red, Experiments 1 and 2 combined, n = 24) and enantiomer discrimination (green, Experiment 1, n = 12). Data points were interpolated (gridded interpolation) and averaged across participants; squares indicate condition-specific mean discrimination accuracies for the training pair in the trained nostril at baseline and at the Day N post-training test. (B) Concentration discrimination accuracies at baseline (Day 0, lighter bars) and at the Day N post-training test (darker bars) for the structurally related and structurally unrelated control pairs, presented to the trained (solid bars) and untrained (striped bars) nostrils. Gray lines represent individual participants. (C, D) Odor intensity (C) and valence (D) ratings at baseline (Day 0, lighter bars) and at the Day N post-training test (darker bars) for the training pair (purple bars) and the structurally related and structurally unrelated control pairs (gray bars), presented to the trained nostril (TN, solid bars) and the untrained nostril (UN, striped bars). (E, F) Trajectories of odor intensity (E) and valence (F) ratings for the training and control concentration pairs (collapsed across structural relatedness) presented to the trained and untrained nostrils across post-training test sessions (Day N, N+1, N+3, N+7, and N+14). Gray lines: individual participants. Error bars: SEMs. *p < 0.05, **p < 0.01, ***p ≤ 0.001.
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Mixture discrimination training induces durable and generalizable olfactory learning independent of odorant structure and concentration
eLife 15:e102999.
https://doi.org/10.7554/eLife.102999
