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Similar or different? The role of the ventrolateral prefrontal cortex in similarity detection.

Garcin B, Volle E, Dubois B, Levy R - PLoS ONE (2012)

Bottom Line: These observations raise the question of whether abstraction and similarity detection are distinct processes involved in abstract categorization, and that depend on separate areas of the prefrontal cortex (PFC).We designed an original experimental paradigm for a functional magnetic resonance imaging (fMRI) study involving healthy subjects, confirming the existence of two distinct processes relying on different prefrontal areas, and thus explaining the behavioural dissociation in frontal lesion patients.We showed that: 1) Similarity detection involves the anterior ventrolateral PFC bilaterally with a right-left asymmetry: the right anterior ventrolateral PFC is only engaged in detecting physical similarities; 2) Abstraction per se activates the left dorsolateral PFC.

View Article: PubMed Central - PubMed

Affiliation: CR-ICM-UPMC, Inserm UMR_S 975;CNRS UMR 7225, Groupe Hospitalier Pitié-Salpêtrière, Paris, France. beagarcin@msn.com

ABSTRACT
Patients with frontal lobe syndrome can exhibit two types of abnormal behaviour when asked to place a banana and an orange in a single category: some patients categorize them at a concrete level (e.g., "both have peel"), while others continue to look for differences between these objects (e.g., "one is yellow, the other is orange"). These observations raise the question of whether abstraction and similarity detection are distinct processes involved in abstract categorization, and that depend on separate areas of the prefrontal cortex (PFC). We designed an original experimental paradigm for a functional magnetic resonance imaging (fMRI) study involving healthy subjects, confirming the existence of two distinct processes relying on different prefrontal areas, and thus explaining the behavioural dissociation in frontal lesion patients. We showed that: 1) Similarity detection involves the anterior ventrolateral PFC bilaterally with a right-left asymmetry: the right anterior ventrolateral PFC is only engaged in detecting physical similarities; 2) Abstraction per se activates the left dorsolateral PFC.

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Reaction times (fMRI study).Histograms represent means ± standard errors of the mean. *:p<.05; **:p<.01; ***:p<.001. SSh: Same Shape; DSh: Different Shape, SCat: Same Category; DCat: Different Category. a. Reaction times for shape (SSh and DSh) and category (SCat and DCat) conditions. Paired t-tests were used for comparisons. b. Reaction times for same (SSh and SCat) and different (DSh and DCat) conditions. Paired t-tests were used for comparisons. c. Reaction times under the four different conditions. ANOVAs were performed for comparisons. Tukey's post hoc analysis confirmed a difference between conditions.
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pone-0034164-g002: Reaction times (fMRI study).Histograms represent means ± standard errors of the mean. *:p<.05; **:p<.01; ***:p<.001. SSh: Same Shape; DSh: Different Shape, SCat: Same Category; DCat: Different Category. a. Reaction times for shape (SSh and DSh) and category (SCat and DCat) conditions. Paired t-tests were used for comparisons. b. Reaction times for same (SSh and SCat) and different (DSh and DCat) conditions. Paired t-tests were used for comparisons. c. Reaction times under the four different conditions. ANOVAs were performed for comparisons. Tukey's post hoc analysis confirmed a difference between conditions.

Mentions: Mean errors were at very low levels and are reported in figure S1. Mean reaction times (RTs) (+/− standard deviation) were shorter for same (shape+category) than for different (shape+category) conditions, with a mean difference of 96 msec (t [19] = 7; p<.0001; Fig. 2b). The best performance (i.e. quickest response) was observed in the same shape condition, followed by different shape, same category and different category conditions (F [3,19] = 55.4; p<.0001; Fig. 2c). ANOVA with repeated measures did not reveal significant differences in RTs across the 8 sessions of the experiment (Figure S2).


Similar or different? The role of the ventrolateral prefrontal cortex in similarity detection.

Garcin B, Volle E, Dubois B, Levy R - PLoS ONE (2012)

Reaction times (fMRI study).Histograms represent means ± standard errors of the mean. *:p<.05; **:p<.01; ***:p<.001. SSh: Same Shape; DSh: Different Shape, SCat: Same Category; DCat: Different Category. a. Reaction times for shape (SSh and DSh) and category (SCat and DCat) conditions. Paired t-tests were used for comparisons. b. Reaction times for same (SSh and SCat) and different (DSh and DCat) conditions. Paired t-tests were used for comparisons. c. Reaction times under the four different conditions. ANOVAs were performed for comparisons. Tukey's post hoc analysis confirmed a difference between conditions.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3316621&req=5

pone-0034164-g002: Reaction times (fMRI study).Histograms represent means ± standard errors of the mean. *:p<.05; **:p<.01; ***:p<.001. SSh: Same Shape; DSh: Different Shape, SCat: Same Category; DCat: Different Category. a. Reaction times for shape (SSh and DSh) and category (SCat and DCat) conditions. Paired t-tests were used for comparisons. b. Reaction times for same (SSh and SCat) and different (DSh and DCat) conditions. Paired t-tests were used for comparisons. c. Reaction times under the four different conditions. ANOVAs were performed for comparisons. Tukey's post hoc analysis confirmed a difference between conditions.
Mentions: Mean errors were at very low levels and are reported in figure S1. Mean reaction times (RTs) (+/− standard deviation) were shorter for same (shape+category) than for different (shape+category) conditions, with a mean difference of 96 msec (t [19] = 7; p<.0001; Fig. 2b). The best performance (i.e. quickest response) was observed in the same shape condition, followed by different shape, same category and different category conditions (F [3,19] = 55.4; p<.0001; Fig. 2c). ANOVA with repeated measures did not reveal significant differences in RTs across the 8 sessions of the experiment (Figure S2).

Bottom Line: These observations raise the question of whether abstraction and similarity detection are distinct processes involved in abstract categorization, and that depend on separate areas of the prefrontal cortex (PFC).We designed an original experimental paradigm for a functional magnetic resonance imaging (fMRI) study involving healthy subjects, confirming the existence of two distinct processes relying on different prefrontal areas, and thus explaining the behavioural dissociation in frontal lesion patients.We showed that: 1) Similarity detection involves the anterior ventrolateral PFC bilaterally with a right-left asymmetry: the right anterior ventrolateral PFC is only engaged in detecting physical similarities; 2) Abstraction per se activates the left dorsolateral PFC.

View Article: PubMed Central - PubMed

Affiliation: CR-ICM-UPMC, Inserm UMR_S 975;CNRS UMR 7225, Groupe Hospitalier Pitié-Salpêtrière, Paris, France. beagarcin@msn.com

ABSTRACT
Patients with frontal lobe syndrome can exhibit two types of abnormal behaviour when asked to place a banana and an orange in a single category: some patients categorize them at a concrete level (e.g., "both have peel"), while others continue to look for differences between these objects (e.g., "one is yellow, the other is orange"). These observations raise the question of whether abstraction and similarity detection are distinct processes involved in abstract categorization, and that depend on separate areas of the prefrontal cortex (PFC). We designed an original experimental paradigm for a functional magnetic resonance imaging (fMRI) study involving healthy subjects, confirming the existence of two distinct processes relying on different prefrontal areas, and thus explaining the behavioural dissociation in frontal lesion patients. We showed that: 1) Similarity detection involves the anterior ventrolateral PFC bilaterally with a right-left asymmetry: the right anterior ventrolateral PFC is only engaged in detecting physical similarities; 2) Abstraction per se activates the left dorsolateral PFC.

Show MeSH
Related in: MedlinePlus