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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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Analysis of variance in the Regions of Interest (ROIs) in the Ventrolateral PFC.Analyses of variance (ANOVAs) were performed for the ventrolateral regions of interest (ROIs) to examine their activation profile during Similarity detection and Abstraction. *: p<.05; **:p<.01; ***:p<.001. SSh: Same Shape, DSh: Different Shape, SCat: Same Category, DCat: Different Category. DLPFC: dorsolateral prefrontal Cortex; VLPFC: Ventrolateral Prefrontal Cortex. In each ROI, two-way ANOVAs were performed to compare activation across the conditions. Shape/Category effect: There was significantly more activation in the left DLPFC (p<.001) and left posterior VLPFC during category than during shape tasks (p<.001). There was a significantly greater signal change in the right anterior VLPFC during shape than during category tasks (p = .025). There was no shape/category effect on activation in the left anterior VLPFC. Same/Different effect: There was significantly more activation during same than during different tasks in the left posterior VLPFC (p<.001), left anterior VLPFC (p = .0000), and right anterior VLPFC (p<.001). Interactions: There was no interaction between similarity detection and abstraction in the ROIs selected.
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pone-0034164-g005: Analysis of variance in the Regions of Interest (ROIs) in the Ventrolateral PFC.Analyses of variance (ANOVAs) were performed for the ventrolateral regions of interest (ROIs) to examine their activation profile during Similarity detection and Abstraction. *: p<.05; **:p<.01; ***:p<.001. SSh: Same Shape, DSh: Different Shape, SCat: Same Category, DCat: Different Category. DLPFC: dorsolateral prefrontal Cortex; VLPFC: Ventrolateral Prefrontal Cortex. In each ROI, two-way ANOVAs were performed to compare activation across the conditions. Shape/Category effect: There was significantly more activation in the left DLPFC (p<.001) and left posterior VLPFC during category than during shape tasks (p<.001). There was a significantly greater signal change in the right anterior VLPFC during shape than during category tasks (p = .025). There was no shape/category effect on activation in the left anterior VLPFC. Same/Different effect: There was significantly more activation during same than during different tasks in the left posterior VLPFC (p<.001), left anterior VLPFC (p = .0000), and right anterior VLPFC (p<.001). Interactions: There was no interaction between similarity detection and abstraction in the ROIs selected.

Mentions: Further analyses were performed in order to determine: 1) whether or not the left and right anterior VLPFC, involved in similarity detection, also participated in abstraction, and 2) whether or not the left mid-VLPFC and the left DLPFC, involved in abstraction, also participated in similarity detection. For this purpose, we selected regions of interest (ROIs) in the following areas: the two largest activated prefrontal clusters identified by the same>different contrast (right and left anterior VLPFC) and the two most ventral clusters identified by the category>shape contrast (left mid VLPFC and left DLPFC) (Fig. 5). We then performed two-way ANOVAs on the parameter estimates extracted for each ROI, orthogonally crossing category (different and same conditions)/shape (different and same conditions) and same (shape and category conditions)/different (shape and category conditions) dimensions.


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

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

Analysis of variance in the Regions of Interest (ROIs) in the Ventrolateral PFC.Analyses of variance (ANOVAs) were performed for the ventrolateral regions of interest (ROIs) to examine their activation profile during Similarity detection and Abstraction. *: p<.05; **:p<.01; ***:p<.001. SSh: Same Shape, DSh: Different Shape, SCat: Same Category, DCat: Different Category. DLPFC: dorsolateral prefrontal Cortex; VLPFC: Ventrolateral Prefrontal Cortex. In each ROI, two-way ANOVAs were performed to compare activation across the conditions. Shape/Category effect: There was significantly more activation in the left DLPFC (p<.001) and left posterior VLPFC during category than during shape tasks (p<.001). There was a significantly greater signal change in the right anterior VLPFC during shape than during category tasks (p = .025). There was no shape/category effect on activation in the left anterior VLPFC. Same/Different effect: There was significantly more activation during same than during different tasks in the left posterior VLPFC (p<.001), left anterior VLPFC (p = .0000), and right anterior VLPFC (p<.001). Interactions: There was no interaction between similarity detection and abstraction in the ROIs selected.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0034164-g005: Analysis of variance in the Regions of Interest (ROIs) in the Ventrolateral PFC.Analyses of variance (ANOVAs) were performed for the ventrolateral regions of interest (ROIs) to examine their activation profile during Similarity detection and Abstraction. *: p<.05; **:p<.01; ***:p<.001. SSh: Same Shape, DSh: Different Shape, SCat: Same Category, DCat: Different Category. DLPFC: dorsolateral prefrontal Cortex; VLPFC: Ventrolateral Prefrontal Cortex. In each ROI, two-way ANOVAs were performed to compare activation across the conditions. Shape/Category effect: There was significantly more activation in the left DLPFC (p<.001) and left posterior VLPFC during category than during shape tasks (p<.001). There was a significantly greater signal change in the right anterior VLPFC during shape than during category tasks (p = .025). There was no shape/category effect on activation in the left anterior VLPFC. Same/Different effect: There was significantly more activation during same than during different tasks in the left posterior VLPFC (p<.001), left anterior VLPFC (p = .0000), and right anterior VLPFC (p<.001). Interactions: There was no interaction between similarity detection and abstraction in the ROIs selected.
Mentions: Further analyses were performed in order to determine: 1) whether or not the left and right anterior VLPFC, involved in similarity detection, also participated in abstraction, and 2) whether or not the left mid-VLPFC and the left DLPFC, involved in abstraction, also participated in similarity detection. For this purpose, we selected regions of interest (ROIs) in the following areas: the two largest activated prefrontal clusters identified by the same>different contrast (right and left anterior VLPFC) and the two most ventral clusters identified by the category>shape contrast (left mid VLPFC and left DLPFC) (Fig. 5). We then performed two-way ANOVAs on the parameter estimates extracted for each ROI, orthogonally crossing category (different and same conditions)/shape (different and same conditions) and same (shape and category conditions)/different (shape and category conditions) dimensions.

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