The claim that humans only use about 10 percent of the brain has not been proven. Even
when Flourens and Lashley took out large parts (90%) of the brain still had its basic
Psychology: the study of behaviour and attempting to describe, explain, change, and
Neuropsychology: the study of behaviour too but a specialty, including the relation between
behaviour and the activity of the brain, assuming that the activity of the brain is partially
responsible for one’s behaviour. There are 2 types of neuropsychology:
Clinical neuropsychology: the branch of neuropsychology dealing with psychological
assessment, management, and rehabilitation of neurological disease and injury.
Experimental Neuropsychology: also known as cognitive neuroscience/
neuropsychology, thebranch of neuropsychology focusing on how human behaviour
arises from brainactivity, including how behavioural changes can be explained in
terms of damaged neuralcomponents.
It is important to learn the history of neuropsychology because there were many instances
in time where scientist created theories about brain and behaviour relationships that are
now proven to be false. Today we know that the brain affects behaviour but in the past that
was not the case.
Empedocles (known for theory about matter being composed of water, air, fire and
earth): a philosopher who proposed the idea of “the cardiac” or “cardiocentric
hypothesis”, where the heart was the source of behaviour. This hypothesis still has an
effect on pop culture today, like how humans associate love with the heart and not the
Aristotle: also came to the conclusion that the heart was the centre involved with
thought and sensation but only because it is warm and active and that since heat rises,
the brain was the blood cooling centre because it is covered with a network of
vasculature so according to him it must have been the radiator. He was wrong the blood
actually helps cool the brain.
Hippocrates and Galen: argues that the brain is not the source of human behaviour,
they proposed the “brain hypothesis” or “cephalocentric hypothesis” where the brain is
responsible for thought and sensation. Both of them were still wrong about some of the
details. Galen thought that the brain’s ventricles and cerebrospinal fluid (supports,
nourishes, cleans brain) played a role in cognition, which was later corrected by Magnus
Despite the ancient claims that the heart controls emotions and intellect, there is evidence
others experimented with brain function. Observations of a fossilized skull fracture suggests
that there was recognition that damaging the brain would cause death or disabling of an
individual. Another skull that was found from 7000 years ago was cut open twice for
surgical purposes and the individual survived this surgery as shown in bone regrowth. This
was done to cure something. Ancient Egyptian writing from 5000 years ago also documents
symptoms of brain damage but they didn’t consider the brain important enough to
mummify . They appreciate the brain in behaviour and perhaps some diseased states. Early
theories did not recognize the importance of the brain in higher cognitive functions. It was
looked at as an interpreter of signals while the mind was characterized as a separate entity
from the brain.
Trephination: producing a hole in the skull to produce therapeutic effects in ancient
times. It was thought that the brain interpreted signals and that the mind was a separate
Mind-Body Problem: The brain – behaviour idea made a lot of phiolosphical questions become
a problem. René Descartes proposed a reflexive theory of controlling behaviour describes as
flowing animal spirits through valvules in nervous tissue. It described how external stimuli
would move the skin then the filaments, releasing spirits and innervating the muscles. It could
account for involuntary behaviour but could not account for voluntary behaviour or the
variability in behaviour. Descartes believed the voluntary behaviours depended on a
mechanical body with a decision-making soul, located in the pineal gland since it doesn’t have a
left and right component it is a midline structure and was surrounded by cerebrospinal fluid
that cleanses and supports the brain (contained animal spirits which produce movement during
voluntary action). Therefore voluntary movement caused movement of the pineal gland,
resulting in the release of animal spirits throughout the body causing the body to move.
Hydraulic machines were in at the time in Paris and this affected his theory. Theories of the
human brain over time really relied on explanations from technologies that were present at the
time. One explanation didn’t even look at the brain as just a computers, it looked at the brain as
a network of computers like todays supercomputers. However with all of this mechanical
associations with behaviour, it still couldn’t solve the variability in behaviour in the same
situations. According to the Harvard Law of Animal Behaviour animals in the same situations
will react as it pleases. However the variability in behaviour isn’t the only problem, Descartes
proposed that the body and mind are separate but interacting entities. This is referred to as
dualism. But what has been left unexplained is how they both interact or what affects what.
Dualism: an idea proposed by Descartes that the mind and body are separate but interact.
Monism: the idea that the mind and body are one, accepted today.
1990s was the age of the brain where a lot was discovered but still rooted back to the
research of the pioneers, it still reached out to many other disciplines too.
Lesioning: destroying tissue in the medulla was discovered by Legallois to stop breathing. This
respiratory centre was the first widely accepted function to be localized in the brain.
Magendie and Bell: they studied the nerves that exited the spinal cord. They discovered that
the dorsal roots that leave the spinal cord on the back have sensory functions and the ventral
roots the nerves that leave the spinal cord from the front had motor functions, which suggested
that the brain could also be divided into sensory and motor areas for functional as well as
anatomical segragational reasons.
Franz Joseph Gall: suggested that the cortex was functionally localized. He stated that the brain
was divided into 27 different areas called faculties (cognitive abilities), which could be found on
the cortex of the human brain (nonhuman animals had 19 of these faculties). However these
faculties were not distinguished well in terms of cognitive abilities but some of the cognitive
localizations he made have been proven today. He also believed the cortex acted as a muscle,
where a larger area was associated with a larger function, for example the wiser a person the
bigger there brain. This increase in size of the cortical area would cause a bump (deformation of