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Quantity without numbers and numbers without quantity in the parietal cortex.

Cappelletti M, Muggleton N, Walsh V - Neuroimage (2009)

Bottom Line: Our results showed that IPS involvement in numerical cognition is neither stimulus-specific nor specific for conceptual tasks.However, IPS-TMS showed no impairment for perceptual decisions on numbers without any conceptual processing (i.e. colour judgment), nor for conceptual decisions that did not involve quantity or number stimuli (e.g. summer object: 'bikini' or 'coat'?).Rather, our results show that the IPS is only necessary when conceptual operations need to be explicitly oriented to numerical concepts.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cognitive Neuroscience and Dept of Psychology, University College London, 17 Queen Square, London WC1N 3AR, UK. m.cappelletti@ucl.ac.uk

ABSTRACT
A dominant view in numerical cognition is that processing the quantity indicated by numbers (e.g. deciding the larger between two numbers such as '12.07' or '15.02') relies on the intraparietal regions (IPS) of the cerebral cortex. However, it remains unclear whether the IPS could play a more general role in numerical cognition, for example in (1) quantity processing even with non-numerical stimuli (e.g. choosing the larger of 'bikini' and 'coat'); and/or (2) conceptual tasks involving numbers beyond those requiring quantity processing (e.g. attributing a summer date to either '12.07' or '15.02'). In this study we applied fMRI-guided TMS to the left and right IPS, while independently manipulating stimulus and task. Our results showed that IPS involvement in numerical cognition is neither stimulus-specific nor specific for conceptual tasks. Thus, quantity judgments with numerical and non-numerical stimuli were equally affected by IPS-TMS, as well as a number conceptual task not requiring quantity comparisons. However, IPS-TMS showed no impairment for perceptual decisions on numbers without any conceptual processing (i.e. colour judgment), nor for conceptual decisions that did not involve quantity or number stimuli (e.g. summer object: 'bikini' or 'coat'?). These results are consistent with proposals that the parietal areas are engaged in the conceptual representation of numbers but they challenge the most common view that number processing is so automatic that the simple presentation of numbers activates the IPS and a sense of magnitude. Rather, our results show that the IPS is only necessary when conceptual operations need to be explicitly oriented to numerical concepts.

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Experimental design. In each trial, participants viewed pairs of stimuli presented one above the other with a fixation cross in the middle of the computer screen. Stimuli could be either two Arabic numbers (left column) or two object names (right column) presented in one of four possible colours (red, yellow, blue, green). Participants were instructed to indicate with a button press which of these stimuli was the correct response to a question consisting of two key words presented above the upper stimulus before and during the stimulus display. There were three types of tasks: for quantity tasks (A), there were four possible types of questions: ‘larger?’, ‘smaller?’, ‘more?’, ‘less?’. For non-quantity categorical tasks (B), there were four different types of questions: ‘summer month/object?’, ‘winter month/object?’, ‘sleeping time/object?’, ‘working time/object?’ (either ‘month’ or ‘object’ was displayed depending on the stimulus condition). For the stimulus-colour decision (C) the questions were: ‘blue/red/yellow/green number or object? The 3 different tasks (quantity, non-quantity categorical and colour-decision) with both stimuli (numbers and object names) were blocked (6 stimuli per block) and presented in pseudo-random. Each condition (e.g. quantity) was first presented with numerical stimuli, e.g. ‘larger number?’ (or object names, e.g. ‘larger object?’) and followed by another block with object names (or numerical stimuli) in a counterbalanced order. Presentation of blocks of the same task with both stimuli was followed by about 16-second rest period where subjects were asked to maintain fixation on a cross in the middle of the computer screen. Trials where the correct answer was the upper or the lower stimulus were presented in equal proportion. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
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fig1: Experimental design. In each trial, participants viewed pairs of stimuli presented one above the other with a fixation cross in the middle of the computer screen. Stimuli could be either two Arabic numbers (left column) or two object names (right column) presented in one of four possible colours (red, yellow, blue, green). Participants were instructed to indicate with a button press which of these stimuli was the correct response to a question consisting of two key words presented above the upper stimulus before and during the stimulus display. There were three types of tasks: for quantity tasks (A), there were four possible types of questions: ‘larger?’, ‘smaller?’, ‘more?’, ‘less?’. For non-quantity categorical tasks (B), there were four different types of questions: ‘summer month/object?’, ‘winter month/object?’, ‘sleeping time/object?’, ‘working time/object?’ (either ‘month’ or ‘object’ was displayed depending on the stimulus condition). For the stimulus-colour decision (C) the questions were: ‘blue/red/yellow/green number or object? The 3 different tasks (quantity, non-quantity categorical and colour-decision) with both stimuli (numbers and object names) were blocked (6 stimuli per block) and presented in pseudo-random. Each condition (e.g. quantity) was first presented with numerical stimuli, e.g. ‘larger number?’ (or object names, e.g. ‘larger object?’) and followed by another block with object names (or numerical stimuli) in a counterbalanced order. Presentation of blocks of the same task with both stimuli was followed by about 16-second rest period where subjects were asked to maintain fixation on a cross in the middle of the computer screen. Trials where the correct answer was the upper or the lower stimulus were presented in equal proportion. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Mentions: For each pair, they were instructed to indicate with a button press which stimulus was the correct response to a question consisting of two key words presented above the upper stimulus before and during a block of 6 trials (see Fig. 1). On every trial, participants were instructed to press the upper or the lower-arrow keys on the keyboard for the upper or the lower stimulus respectively.3 Trials where the correct answer was the upper or the lower stimulus were presented in equal proportion.


Quantity without numbers and numbers without quantity in the parietal cortex.

Cappelletti M, Muggleton N, Walsh V - Neuroimage (2009)

Experimental design. In each trial, participants viewed pairs of stimuli presented one above the other with a fixation cross in the middle of the computer screen. Stimuli could be either two Arabic numbers (left column) or two object names (right column) presented in one of four possible colours (red, yellow, blue, green). Participants were instructed to indicate with a button press which of these stimuli was the correct response to a question consisting of two key words presented above the upper stimulus before and during the stimulus display. There were three types of tasks: for quantity tasks (A), there were four possible types of questions: ‘larger?’, ‘smaller?’, ‘more?’, ‘less?’. For non-quantity categorical tasks (B), there were four different types of questions: ‘summer month/object?’, ‘winter month/object?’, ‘sleeping time/object?’, ‘working time/object?’ (either ‘month’ or ‘object’ was displayed depending on the stimulus condition). For the stimulus-colour decision (C) the questions were: ‘blue/red/yellow/green number or object? The 3 different tasks (quantity, non-quantity categorical and colour-decision) with both stimuli (numbers and object names) were blocked (6 stimuli per block) and presented in pseudo-random. Each condition (e.g. quantity) was first presented with numerical stimuli, e.g. ‘larger number?’ (or object names, e.g. ‘larger object?’) and followed by another block with object names (or numerical stimuli) in a counterbalanced order. Presentation of blocks of the same task with both stimuli was followed by about 16-second rest period where subjects were asked to maintain fixation on a cross in the middle of the computer screen. Trials where the correct answer was the upper or the lower stimulus were presented in equal proportion. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2683244&req=5

fig1: Experimental design. In each trial, participants viewed pairs of stimuli presented one above the other with a fixation cross in the middle of the computer screen. Stimuli could be either two Arabic numbers (left column) or two object names (right column) presented in one of four possible colours (red, yellow, blue, green). Participants were instructed to indicate with a button press which of these stimuli was the correct response to a question consisting of two key words presented above the upper stimulus before and during the stimulus display. There were three types of tasks: for quantity tasks (A), there were four possible types of questions: ‘larger?’, ‘smaller?’, ‘more?’, ‘less?’. For non-quantity categorical tasks (B), there were four different types of questions: ‘summer month/object?’, ‘winter month/object?’, ‘sleeping time/object?’, ‘working time/object?’ (either ‘month’ or ‘object’ was displayed depending on the stimulus condition). For the stimulus-colour decision (C) the questions were: ‘blue/red/yellow/green number or object? The 3 different tasks (quantity, non-quantity categorical and colour-decision) with both stimuli (numbers and object names) were blocked (6 stimuli per block) and presented in pseudo-random. Each condition (e.g. quantity) was first presented with numerical stimuli, e.g. ‘larger number?’ (or object names, e.g. ‘larger object?’) and followed by another block with object names (or numerical stimuli) in a counterbalanced order. Presentation of blocks of the same task with both stimuli was followed by about 16-second rest period where subjects were asked to maintain fixation on a cross in the middle of the computer screen. Trials where the correct answer was the upper or the lower stimulus were presented in equal proportion. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Mentions: For each pair, they were instructed to indicate with a button press which stimulus was the correct response to a question consisting of two key words presented above the upper stimulus before and during a block of 6 trials (see Fig. 1). On every trial, participants were instructed to press the upper or the lower-arrow keys on the keyboard for the upper or the lower stimulus respectively.3 Trials where the correct answer was the upper or the lower stimulus were presented in equal proportion.

Bottom Line: Our results showed that IPS involvement in numerical cognition is neither stimulus-specific nor specific for conceptual tasks.However, IPS-TMS showed no impairment for perceptual decisions on numbers without any conceptual processing (i.e. colour judgment), nor for conceptual decisions that did not involve quantity or number stimuli (e.g. summer object: 'bikini' or 'coat'?).Rather, our results show that the IPS is only necessary when conceptual operations need to be explicitly oriented to numerical concepts.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cognitive Neuroscience and Dept of Psychology, University College London, 17 Queen Square, London WC1N 3AR, UK. m.cappelletti@ucl.ac.uk

ABSTRACT
A dominant view in numerical cognition is that processing the quantity indicated by numbers (e.g. deciding the larger between two numbers such as '12.07' or '15.02') relies on the intraparietal regions (IPS) of the cerebral cortex. However, it remains unclear whether the IPS could play a more general role in numerical cognition, for example in (1) quantity processing even with non-numerical stimuli (e.g. choosing the larger of 'bikini' and 'coat'); and/or (2) conceptual tasks involving numbers beyond those requiring quantity processing (e.g. attributing a summer date to either '12.07' or '15.02'). In this study we applied fMRI-guided TMS to the left and right IPS, while independently manipulating stimulus and task. Our results showed that IPS involvement in numerical cognition is neither stimulus-specific nor specific for conceptual tasks. Thus, quantity judgments with numerical and non-numerical stimuli were equally affected by IPS-TMS, as well as a number conceptual task not requiring quantity comparisons. However, IPS-TMS showed no impairment for perceptual decisions on numbers without any conceptual processing (i.e. colour judgment), nor for conceptual decisions that did not involve quantity or number stimuli (e.g. summer object: 'bikini' or 'coat'?). These results are consistent with proposals that the parietal areas are engaged in the conceptual representation of numbers but they challenge the most common view that number processing is so automatic that the simple presentation of numbers activates the IPS and a sense of magnitude. Rather, our results show that the IPS is only necessary when conceptual operations need to be explicitly oriented to numerical concepts.

Show MeSH
Related in: MedlinePlus