November 14, 12
PSYCH Lecture Week 10
Localization, Lateralization, and Plasticity
Localization of function
Lateralization of function
Myth: creative brain on the right side, analytics on the left side is a myth. Left brain vs.
right brain isn’t true – there are some specializations but they aren’t so complete.
To what extent can we understand the brain as a single integrated organ that works
together to accomplish thought and behaviour? To what extent is it functionally
specialized? Both of the understandings are true.
The pop culture idea of the right vs. the left is taken to extremes and they are wrong.
There are very dense connections between areas of the brain, so it sometimes doesn’t
make sense to single out specific areas for functions, that is, it often doesn’t make sense
to talk about brain functions being located in particular areas.
Connections in the brain are generally bidirectional – for every connection from area A to
B, there is an equality dense connection from B back to A.
Function of the brain is determined by the structural and chemical composition, and
connection of the area.
Functions like memory or language are so complex that they rely on networks, and dense
interconnections to accomplish these highly complex functions. So it doesn’t rely on
discreet, specialized regions of the brain.
Localization of function in the brain
Phrenology: in the 1800s, not scientific in its origins, had a lasting impact on psychology.
Flourens (1824): Origin of the idea that brain functions can be found in discreet areas of
the cortex. However, the functions recognized were not well received and don’t hold true
today. Flourens started the experimental technique of legions, on pigeons and rabbits.
Found several things out, but couldn’t find out specific things.
Broca (1861): Localization of function – stroke damage that caused a person to loss
ability to use language, first
Fritsch and Hitzig (1870): mapping of the dog’s motor cortex, supporting that functions
are localized in the brain.
All of this work has led us to our current understanding: Several local centres work
together in parallel to support complex functions.
The Cerebral Cortex November 14, 12
Anatomical support that the brain is not just one thing, that there is some specialization to
it. The layers of cortex made visible using three different anatomical stains…the staining
techniques were used to show the different structural features of the cortex, stainging in a
certain way shows the cells clearly. Different layers have different kinds of cells in them.
This shows us that different parts of the brain have different structures.
Grey matter and white matter – we can divide the brain up into different structures that
have things in common, like tissue matter.
Brodmann Map (1909): began to divide the brain up.
Methods used before the 1940s to study localization of