The somatosensory cortex has large regions devoted to input from the fingers 
(and hands) and the facial region.  I'm sure many people are familiar with 
the homunculus and his large hands and big face.  These sensory maps are 
moulded by experience- both prenatally and postnatally.   It is known that 
the presence or absence of sensory input can have a significant effect on 
the organization of the cortex.  Tactile stimulation helps to enhance 
neuronal networks, where as deprivation has the opposite effect.  There is a 
substantial amount research on the plasticity of the somatosensory cortex, 
however, these studies are mainly from non-humans.  For example, removal of 
the vibrissa in rat pups leads to changes in the neuronal organization rat 
barrel cortex.  The vibrissa in rodents are somewhat analogous to fingers in 
humans.

The timing of somatosensory development is not identical between rodents and 
humans, although it is likely that tactile experience postnatally is 
important for the normal development of the somatosensory cortex in both 
species.  However, removing the vibrassa is not analogous to covering the 
hands.  A baby whose hands are covered will still be receiving some sensory 
input through their finger tips and it is unlikely that their hands will be 
covered 100% of the time.  Also, the somatosensory cortex retains a certain 
amount of plasticity throughout childhood and into adulthood- so there is 
still lots of opportunity for tactile experience to have an effect on 
cortical organization as baby gets older.  The door doesn't close a few days 
or weeks after birth.  However, a baby whose hands are uncovered has an 
opportunity for a richer assortment of tactile experiences and perhaps this 
could have an impact on brain development.

I don't know if there are any published studies examining the effects of 
hand covering on human brain development in the early postnatal period.

Suzanne Nurse, PhD
LLL Leader, Ontario Canada 

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