How the brain knows a dog is a dog
24 September 2009
One of the defining characteristics of human intelligence is the ability to use prior knowledge when dealing with new situations through the development of 'concepts'. For example, we know that an animal that barks, has four legs, is furry and has a snout is likely to be a dog.
"Although a poodle and a golden retriever look very different from each other, we can easily appreciate their similar attributes because they can be recognised as instances of a particular concept, in this case a dog," explains Dr Dharshan Kumaran from the Wellcome Trust Centre for Neuroimaging at University College London.
Yet while there is little doubt that humans form and use concepts all the time, very little is known about how conceptual knowledge is created in the brain or how it allows us to make efficient choices.
Now, Dr Kumaran and colleagues have used behavioural and neuroimaging techniques to reveal how this knowledge emerges in the human brain, and how it is used to guide decision making. The results of the study, which was funded by the Wellcome Trust, are published in the journal 'Neuron'.
In the study, 25 volunteers were asked to predict whether the weather would be sunny or raining based on the appearance of the night sky. The night sky was represented by patterns on a computer screen. If correct, the participants could win money.
Initially, participants tended to memorise the outcome associated with specific patterns. However, it soon became clear to the participants that groups of patterns were conceptually related - by applying this information, participants were able to solve the task in a different setting where the concepts were similar but the patterns themselves new.
By applying fMRI scanning techniques, which measure changes in blood flow in the brain to identify areas of activity, Dr Kumaran and colleagues were able to show that the emergence of conceptual knowledge was underpinned by a coupled circuit involving the hippocampus (an area of the brain responsible for learning and memory) and the ventromedial prefrontal cortex (used in decision-making).
Most significantly, however, the researchers found that activity in the hippocampus alone predicted which participants would be able to successfully apply the concepts they had learned in a new setting. This suggests that the hippocampus creates and stores these concepts, and passes this information to the prefrontal cortex where it can be put to use, for example in making choices where financial reward is at stake.
The results highlight the role of the hippocampus in acquiring new concepts, possibly through its unique networking capacities, which allow multiple memories to be related to one another.
"Our study offers neurobiological insights into the remarkable capacity of humans to develop concepts based on their visual experiences," say Dr Kumaran. "It reveals how so-called 'memory' regions like the hippocampus team up with 'decision modules' in the prefrontal lobe to put this information to use."
Image: Chinese crested dog. Credit: Tommy Gildseth
Contact
Craig Brierley
Senior Media Officer
Wellcome Trust
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c.brierley@wellcome.ac.uk
Notes for editors
Kumaran D et al. Tracking the emergence of conceptual knowledge during human decision making. Neuron 2009.
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