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Adult consciousness in five-month-old babies

By Eko Armunanto     Jun 6, 2013 in Science
Babies are able to think and store memories from as early as five-months-old, according to new research. French scientists discovered that the brain processes a great deal of visual information before any of it reaches a level of conscious awareness.
Once an adult brain detects something, such as a moving object, a signal travels through the brain allowing it to briefly store the image. A spike in brain activity is visible when this happens and also when the brain’s prefrontal cortex receives the message – this spike in brain activity is known as a ‘late slow wave’. The researchers wanted to discover when these spikes in brain activity could also be detected in babies
Researchers in France led by Dr Sid Kouider of the Ecole Normale Superieure in Paris wondered if such a two-step pattern might be present in infants. They monitored infants’ brain activity through caps fitted with electrodes. About 240 babies, ages 5 months, 12 months, or 15 months, participated, but two-thirds were too squirmy for the movement-sensitive caps. The remaining 80 babies were shown a picture of a face on a screen for a fraction of a second
Looking for consciousness in babies too young to talk, they took the advantage of research on visual perception, which showed that the brain processes a great deal of visual information before any of it reaches a level of conscious awareness. EEG signals measured by placing electrodes on the head can clearly differentiates between visual data that is consciously seen and that which is simply taken in by the brain. These signals show a major alteration when a person first becomes consciously aware of an object that has previously received only subliminal attention.
They watched for swings in electrical activity, known as Event-Related Potentials (ERPs), in the babies’ brains. In babies who were at least 1 year old, Kouider saw a pattern of ERP similar to adult’s but it was about three times slower. They were surprised to see that the 5-month-olds also showed a late slow wave, although it was weaker and more drawn out than in the older babies. Kouider speculates that the late slow wave may be present in babies as young as 2 months.
Kouider explains there are two stages of perceptual processing. Activation of neurons in the sensory cortex is the first stage. Just a little visual stimulation, even if you can’t see it consciously, is going to activate this brain region. The brain, he says, still shows electrical activity on an EEG, for example, even if images or words flash by so quickly that they aren’t consciously perceived. This information registers somewhere in the brain, however, because such “subliminal” data can affect responses to later tasks. The second stage, reported verbally by adults, comes with a distinctive signal and is essentially either all, when you can see it, or none, if the object isn’t visible at all, signifying a conscious level of attention and processing.
“The team displayed remarkable patience to gather data from infants,” says cognitive neuroscientist Lawrence Ward of the University of British Columbia, Vancouver, in Canada, who was not involved in the study. But the well-executed work is not the last word, he says. “I expect we’ll find several different neural activity patterns to be correlated with consciousness.”
“Comparing infant brain waves to adult patterns is tricky,” says Charles Nelson, a neuropsychologist at Harvard Medical School in Boston. ERP components, according to him, change dramatically over the first few years of life. “I would be reluctant to attribute the same mental operation (i.e., consciousness) in infants as in adults simply because of similar patterns of brain activity,” he says.
Agrees with that notion, Kouider says “He’s right, the ERP components are not exactly the same as in adults,” – but the ERP signature he saw had the same characteristics. His next plan is to study how these signs of conscious thought are related to learning, especially to the development of language. “We make the assumption that babies are learning very quickly and that they’re fully unconscious of what they learn. Maybe that’s not true,” he says.
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