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# Categorization in single neurons

## Details

**Authors** Pellegrino

**Year** 2001

**Publisher** Trends in Cognitive Sciences

**Discipline** Neuroscience

[Read it at the publisher](https://doi.org/10.1016/s1364-6613(00)01669-7) 
10.1016/s1364-6613(00)01669-7

## In authors' words

### What they set out to do (purpose)

Summary of research done on how categorization functions in neurons.

### What they found (results)

The monkeys had a surprisingly high success rate of categorization (90%) even when the image was close to being a 50-50 split. For example, if the split was 60% dog and 40% cat, the monkey would correctly categorize the image as dog 90% of the time. In addition, they found that the neurons fired differently when the split was 60/40 dog to cat, then when it was 60/40 cat to dog. Neurons responded differently to stimuli that were morphologically similar (i.e., dog and cat) but rested on opposite sides on the spectrum than it did to stimuli that were morphologically different (i.e., dog and shark).

## Commentary

### In short

Categorical knowledge and the elemental patterns of part-whole systems is explicitly represented in the firing rates of prefrontal neurons.

### In more detail

While Anderson offered that categorization can be predicted from the external environment, Pellegrino, 2001 implied that categorization is a shortcut to deal with complex environments or concepts. Pellegrino reported on experiments in which morphs of dogs and cats were made, so that each image was a certain percentage of a cat and a dog, but the images were never 100% dog or cat. The images were shown to monkeys, and the monkeys had a surprisingly high success rate of categorization (90%) even when the image was close to being a 50-50 split. For example, if the split was 60% dog and 40% cat, the monkey would correctly categorize the image as dog 90% of the time. In addition, they found that the neurons fired differently when the split was 60/40 dog to cat, then when it was 60/40 cat to dog.

They observed that “categorical knowledge is explicitly represented in the firing rates of prefrontal neurons.” He also found that neurons responded differently to stimuli that were morphologically similar (i.e., dog and cat) but rested on opposite sides on the spectrum than it did to stimuli that were morphologically different (i.e., dog and shark). This led to further exploration of where in the brain the act of categorization - or organizing into parts and whole systems occurs.

**Patterns it shows** S

**How to cite this** Pellegrino (2001). Categorization in single neurons. Trends in Cognitive Sciences.