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Monday, 20 June 2016

Introducing Alice


photograph of Alice Wayne


Saturday, 18 June 2016

The Case of the Jumping Carbons






Sunday, 12 June 2016

Face blindness

How do we recognise faces?

Most humans can recognise hundreds of faces, and tell the identity of each one, even in different lighting conditions or when someone has changed their hair colour or aged considerably. But how this works, and how our brain codes for individual people’s identity isn’t known. I spoke to Dr Meike Ramon from the University of Glasgow and University of Louvain, who studies face recognition, to uncover why we still don’t understand this seemingly simple ability.

One famous study using single cell recordings from people undergoing brain surgery claimed to discover a ‘Jennifer Aniston Neuron’[1]. The neuroscientists believed they had found a neuron that responded specifically to pictures of the movie star, suggesting information about the identity of a face may be stored in a single cell. However, these findings should be taken with caution. First, an experiment is always limited in terms of the number and type of stimuli it can test for. Second, we don’t have enough individual cells in our brains to assign one to each of the people we have come into contact with, meaning it can’t be as simple as one cell for each person. It was also discovered that the so called ‘Jennifer Aniston cell’ responded to information relating to her, as well as images, suggesting identity is more complex than was first thought.

Prosopagnosia, or face blindness, is an impairment of the ability to recognise faces that have been seen before.
Image © Yelisa van der Bij (CC BY)

Since the invention of brain-scanning techniques, researchers have tried to find regions of the brain that are involved in face processing; probably the best studied of these is the Fusiform Face Area (FFA)[2]. But while this area is activated more when subjects are looking at faces than at other objects, it is also activated in chess grand masters viewing chess board layouts[3], suggesting that the area might be engaged when looking at anything we are experts in, which for most of us includes faces. It also shows increased activation towards curved and symmetrical images[4], leading to the idea that this area is involved in extracting global patterns for discrimination. As important as this region may be, it is now clear that it alone is not sufficient for face recognition, which seems to depend on a network of regions[5].

One way of studying our normal ability to recognise the faces of people we know is to look at people who don’t have this ability. These people suffer from a condition known as prosopagnosia, or ‘face-blindness’, which can be present from birth or brought on by brain damage. While they may be unaffected in other areas of cognition, prosopagnosia cannot recognise celebrities, their loved ones, or even themselves without using other clues like voice and posture. This is an ability most of us take for granted, but losing it can have a huge impact on a person’s life.