Neuropsychology: The Numerate Brain

Question 1

What are the characteristics of the processing of number symbols?

Answer 1

-Symbolic vs non-symbolic number cognition
-Distance vs size effect

Question 2

What is symbolic number cognition?

Answer 2

Symbolic stimuli: consist of words and digits as representation of number
-6 of six

Question 3

What is non-symbolic number cognition?

Answer 3

Non-symbolic stimuli: consist of collections and quantities as representation of number
-. . . . . .

Question 4

What is the distance effect?

Answer 4

-Distance between numbers
-Comparing numbers easier when distance between numbers is bigger
–>Reaction time less in 3-6 than 5-6
-Effect stronger in non-symbolic than in symbolic stimuli

Question 5

What is the size effect?

Answer 5

-Size of numbers themselves
-Comparing numbers easier when set of numbers is smaller
–>Reaction time less in 4-2 than 20-18
-Effect stronger in non-symbolic than in symbolic stimuli

Question 6

What is the neural substrate of number meaning?

Answer 6

-Intraparietal sulcus (IPS)
-(Pre)frontal areas/cortex

Question 7

How is the intraparietal sulcus (IPS) important for number processing?

Answer 7

-Number neurons found in intraparietal sulcus and prefrontal cortex: neurons that respond preferentially to particular set sizes
-Calculation and letter naming: subtraction between neural activity while calculating and while doing letter naming activates several brain regions: intraparietal sulcus and frontal areas
-Lesion studies: people with difficulties in mathematical tasks after brain damage (acalculia) often have lesions in intraparietal sulcus

Question 8

What was found about number representations in the intraparietal sulcus in the single-neuron selectivity study in monkeys?

Answer 8

Response in IPS and PFC to non-symbolic stimuli
-Neurons show tuning curve
-Tuning curves flatten in higher numbers
-Explains distance and size effect

Question 9

What was found about number representations in the intraparietal sulcus in the fMRI study about selectivity in humans?

Answer 9

Selectivity of numbers related to disorders
-Study: difference in neural response between numbers
–>Able to differentiate between conditions
–>Able to quantify how big difference in neural response is
–>Gives measure of selectivity: how selective is response of neuron
-Results
–>Both in control and dyscalculia group: brain regions that can differentiate between different number conditions
–>In comparison: intraparietal sulcus and prefrontal cortex more selective in control group than in dyscalculia group