One way of assigning meaning and behavioural relevance to sensory stimuli is to categorize them - if our brains didn't do this, the world would be a pretty confusing place. For example, a continuous distribution of target speeds can be grouped into 'fast' or 'slow' categories. Neuroscientists have now characterized brain cells that seem to reflect this sorting process in monkey brains.
David Freedman and John Assad trained rhesus monkeys (Macaca mulatto) to divide dots moving on a screen into two categories, depending on their direction of movement. As they report, in a paper published online by Nature, the activity of neurons in a brain region called the lateral intraparietal (LIP) area strongly corresponded with the motion direction category viewed by the monkeys. When the monkeys were retrained to group the same stimuli into two new categories, the activity of neurons in the LIP changed to reflect the new rule.
This suggests that neurons in the LIP may play an important part in the process of transforming visual information into representative forms that allow us to attach meaning to stimuli.
David Freedman (Harvard Medical School, Boston, MA, USA)
(C) Nature press release.
Message posted by: Trevor M. D'Souza