Split brain research into hemispheric lateralisation
Split-brain research
Hemispheric lateralisation
As we have already seen, the ability to produce and understand language, for
most people, is controlled by the left hemisphere. This suggests that for the
majority of us, language is subject to hemispheric lateralisation. In other words,
the specialised areas associated with language are found in one of the brain's
hemispheres rather than both. The question of whether other neural processes
may be organised in this way was investigated in a series of ingenious experiments
conducted by Roger Sperry and his colleagues (known as split-brain research) for
which Sperry was awarded the Nobel Prize in 1981.
Split-brain studies
Sperry's (1968) studies involved a unique group of individuals, all of whom had
undergone the same surgical procedure - an operation called a commissurotomy
- in which the corpus callosum and other tissues which connect the two
hemispheres were cut down the middle in order to separate the two hemispheres
and control frequent and severe epileptic seizures. This meant that for these
split-brain patients the main communication line between the two hemispheres
was removed. This allowed Sperry and his colleagues to see the extent to which
the two hemispheres were specialised for certain functions, and whether the
hemispheres performed tasks independently of one another.
Procedure
Sperry devised a general procedure in which an image or word could be projected to a
patient's right visual field (processed by the left hemisphere) and the same, or different,
image could be projected to the left visual field (processed by the right hemisphere). In the
'normal' brain, the corpus callosum would immediately share the information between both
hemispheres giving a complete picture of the visual world.
However, presenting the image to one hemisphere of a split-brain patient meant that the
information could not be conveyed from that hemisphere to the other.
Split-brain research
Hemispheric lateralisation
As we have already seen, the ability to produce and understand language, for
most people, is controlled by the left hemisphere. This suggests that for the
majority of us, language is subject to hemispheric lateralisation. In other words,
the specialised areas associated with language are found in one of the brain's
hemispheres rather than both. The question of whether other neural processes
may be organised in this way was investigated in a series of ingenious experiments
conducted by Roger Sperry and his colleagues (known as split-brain research) for
which Sperry was awarded the Nobel Prize in 1981.
Split-brain studies
Sperry's (1968) studies involved a unique group of individuals, all of whom had
undergone the same surgical procedure - an operation called a commissurotomy
- in which the corpus callosum and other tissues which connect the two
hemispheres were cut down the middle in order to separate the two hemispheres
and control frequent and severe epileptic seizures. This meant that for these
split-brain patients the main communication line between the two hemispheres
was removed. This allowed Sperry and his colleagues to see the extent to which
the two hemispheres were specialised for certain functions, and whether the
hemispheres performed tasks independently of one another.
Procedure
Sperry devised a general procedure in which an image or word could be projected to a
patient's right visual field (processed by the left hemisphere) and the same, or different,
image could be projected to the left visual field (processed by the right hemisphere). In the
'normal' brain, the corpus callosum would immediately share the information between both
hemispheres giving a complete picture of the visual world.
However, presenting the image to one hemisphere of a split-brain patient meant that the
information could not be conveyed from that hemisphere to the other.
