Monotonic Coding of Numerosity in Macaque Lateral Intraparietal Area
2007

How Monkeys Count: Neurons in the Brain Area for Number Processing

Sample size: 57 publication 10 minutes Evidence: high

Author Information

Author(s): Roitman Jamie D, Brannon Elizabeth M, Platt Michael L

Primary Institution: Duke University

Hypothesis

Do neurons in the lateral intraparietal area of monkeys encode the total number of elements in a visual array?

Conclusion

Neurons in the lateral intraparietal area of monkeys respond in a graded manner to the number of items in a visual array, suggesting they accumulate numerical information.

Supporting Evidence

  • Neurons in the lateral intraparietal area showed graded responses to the number of elements in a visual array.
  • Responses of these neurons were independent of attention and reward expectations.
  • More than 50% of the neurons recorded were sensitive to numerical quantity.

Takeaway

Monkeys have special brain cells that help them count things, and these cells get more active when there are more items to count.

Methodology

The study recorded the activity of single neurons in the lateral intraparietal area of monkeys while they performed a numerical discrimination task with varying numerosities.

Potential Biases

Potential biases may arise from the specific task design and the training of the monkeys.

Limitations

The study was conducted on a small sample of monkeys, which may limit the generalizability of the findings.

Participant Demographics

Two adult rhesus macaque monkeys (Macaca mulatta) were used as subjects.

Statistical Information

P-Value

p<0.0001

Confidence Interval

−8.68 to −2.46

Statistical Significance

p<0.0001

Digital Object Identifier (DOI)

10.1371/journal.pbio.0050208

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