Features and functions of the brain
● made up of about 100 billion neurons, which are connected to the remainder
of the body via the spinal cord and associated peripheral nerves
● contributes to bodily processes (such as the endocrine system), our ability to
imagine, develop complex languages and communication tools, problem solve and
reason, and have hopes and dreams for the future.
● Takes up around 1300 cm³ of space and weight around 1.4-1.5 kg
● Brain is enclosed by the skull (hard bony case) and three layers of membrane
(meninges) which protect it
● Brain is surrounded by cerebrospinal fluid, which circulates between the meninges
and acts as an additional cushion
● A network of arteries supplies a rich blood flow to the billions of neurons and other
cells that make up the brain so that they can carry out their vital work.
Understanding of the role of the brain over time
The brain-heart debate (c475 BCE - c1650)
● It was questioned whether our thoughts, feelings and behaviours originate from our
brain or our heart
● Perspectives
○ Greek philosopher Alcmaeon identified mental processes as being housed in
the brain and concluded that sensory organs, such as the eye, were
connected to the brain
○ Greek philosophers such as Empedocles and Aristotle argued
that mental processes were located in and around the heart, and Empedocles
also argued that perceptions were formed in the blood
● Investigation
○ Greek physicians such as Hippocrates and Herophilus agreed with Alcmaeon.
Much of their thinking came from their work dissecting the bodies of animals
and some humans
○ Greek physician Galen also agreed with Alcmaeon and made many of his
discoveries through treating Roman gladiators. He observed that injury to
the head and brain affected behaviour, while gladiators who had injuries to
their hearts were still able to think and reason. He concluded that this
demonstrated that such processes did not lie within the heart, and through
additional tests, he determined that they were housed in the brain
,Mind-body problem (c1640 - now)
● Considers the extent to which the mind and the body are the same or separate
things
● Perspectives
○ Aristotle believed that the soul was the living essence of a person’s physical
body, and that the mind and body were one and the same.
○ French philosopher Rene Descartes outlined his theory of ‘dualism’, in which
he suggested that the mind and the body were separate entities, one physical
in nature and one non-physical
○ Over time, scientists have come to understand that the mind and the body
can influence one another in myriad ways, and there is no one central
structure that forms a link between the two.
Phrenology (1796 - c1840s)
● the study of the shape of the skull as an indicator of the extent of one’s mental
faculties and character traits
● Through his studies and comparisons of animal and human skulls and brains, Franz
Joseph Gall believed:
○ that each part of the cerebral cortex was enlarged or reduced depending on
the individual’s mental faculties, traits and personality
○ These differences resulted in subtle changes in the contours of the skull that
could be felt externally
○ that certain areas of the brain were responsible for specific functions and
that bumps and indentations on the head could be linked to the personality,
character and abilities of the individual
● Along with Johann Spurzheim, Gall developed a system of 27 ‘faculties’, each of
which he believed belonged to a different region of the head.
● Although phrenology as a science has been discounted, Gall’s idea that particular
areas of the brain play a significant role in the functioning of different areas of the
body was accurate
Brain experiments (c1800 - now)
● Ablation
○ the surgical removal or destruction of tissue (e.g. brain tissue) by lesioning or
using electrodes
○ Used to determine whether this caused any changes in behaviour or function
● Lesioning
○ the creation of small areas of damage (lesions) in the brain
, ○ challenged the notions of phrenology and established the idea of ‘holistic’
brain function
○ First done by Pierre Flourens then Karl Lashley
○ Was able to determine what parts of the brains were involved in doing
■ E.g. removing small sections of the cortex initially resulted in loss of
movement
○ Lesioning done by Lashley led him to develop the two brain function
principles of equipotentiality (the ability of healthy areas of the cortex to take
over the functions of injured parts) and mass action (the involvement of large
areas of the brain
in functioning as a whole in order to carry out complex functions)
○ Done on animals
● Electrodes
○ small wires used to electrically stimulate biological tissues or measure
electrical activity in these tissues
○ If an electrode is placed on or into a specific area of the brain and stimulation
leads to a bodily response, it can be assumed that area of the brain is
responsible for that action
○ Wilder Penfield used electrodes to understand epilepsy as he sought to
remove the sections of the brain that contributed to seizures. He used
electrodes to locate the abnormally functioning brain tissue, by recording the
responses of his patients who were conscious. As a result, he and his
colleagues created a brain map
Neuroimaging (1890s - now)
● captures an image of the brain
● Structural neuroimaging techniques are MRI and CT → obtain images of the
anatomy of the brain
● Functional neuroimaging techniques are PET and fMRI captures an image of the
brain → view the brain ‘live’ during a response and provide information about both
function and structure
● CT
○ combines a series of x-ray images taken from different angles to create
cross-sectional images of the body
○ The patient may be required to take or be injected with
a substance referred to as ‘contrast’. Helps to make certain structures more
visible, thereby assisting with the interpretation of the images.
● made up of about 100 billion neurons, which are connected to the remainder
of the body via the spinal cord and associated peripheral nerves
● contributes to bodily processes (such as the endocrine system), our ability to
imagine, develop complex languages and communication tools, problem solve and
reason, and have hopes and dreams for the future.
● Takes up around 1300 cm³ of space and weight around 1.4-1.5 kg
● Brain is enclosed by the skull (hard bony case) and three layers of membrane
(meninges) which protect it
● Brain is surrounded by cerebrospinal fluid, which circulates between the meninges
and acts as an additional cushion
● A network of arteries supplies a rich blood flow to the billions of neurons and other
cells that make up the brain so that they can carry out their vital work.
Understanding of the role of the brain over time
The brain-heart debate (c475 BCE - c1650)
● It was questioned whether our thoughts, feelings and behaviours originate from our
brain or our heart
● Perspectives
○ Greek philosopher Alcmaeon identified mental processes as being housed in
the brain and concluded that sensory organs, such as the eye, were
connected to the brain
○ Greek philosophers such as Empedocles and Aristotle argued
that mental processes were located in and around the heart, and Empedocles
also argued that perceptions were formed in the blood
● Investigation
○ Greek physicians such as Hippocrates and Herophilus agreed with Alcmaeon.
Much of their thinking came from their work dissecting the bodies of animals
and some humans
○ Greek physician Galen also agreed with Alcmaeon and made many of his
discoveries through treating Roman gladiators. He observed that injury to
the head and brain affected behaviour, while gladiators who had injuries to
their hearts were still able to think and reason. He concluded that this
demonstrated that such processes did not lie within the heart, and through
additional tests, he determined that they were housed in the brain
,Mind-body problem (c1640 - now)
● Considers the extent to which the mind and the body are the same or separate
things
● Perspectives
○ Aristotle believed that the soul was the living essence of a person’s physical
body, and that the mind and body were one and the same.
○ French philosopher Rene Descartes outlined his theory of ‘dualism’, in which
he suggested that the mind and the body were separate entities, one physical
in nature and one non-physical
○ Over time, scientists have come to understand that the mind and the body
can influence one another in myriad ways, and there is no one central
structure that forms a link between the two.
Phrenology (1796 - c1840s)
● the study of the shape of the skull as an indicator of the extent of one’s mental
faculties and character traits
● Through his studies and comparisons of animal and human skulls and brains, Franz
Joseph Gall believed:
○ that each part of the cerebral cortex was enlarged or reduced depending on
the individual’s mental faculties, traits and personality
○ These differences resulted in subtle changes in the contours of the skull that
could be felt externally
○ that certain areas of the brain were responsible for specific functions and
that bumps and indentations on the head could be linked to the personality,
character and abilities of the individual
● Along with Johann Spurzheim, Gall developed a system of 27 ‘faculties’, each of
which he believed belonged to a different region of the head.
● Although phrenology as a science has been discounted, Gall’s idea that particular
areas of the brain play a significant role in the functioning of different areas of the
body was accurate
Brain experiments (c1800 - now)
● Ablation
○ the surgical removal or destruction of tissue (e.g. brain tissue) by lesioning or
using electrodes
○ Used to determine whether this caused any changes in behaviour or function
● Lesioning
○ the creation of small areas of damage (lesions) in the brain
, ○ challenged the notions of phrenology and established the idea of ‘holistic’
brain function
○ First done by Pierre Flourens then Karl Lashley
○ Was able to determine what parts of the brains were involved in doing
■ E.g. removing small sections of the cortex initially resulted in loss of
movement
○ Lesioning done by Lashley led him to develop the two brain function
principles of equipotentiality (the ability of healthy areas of the cortex to take
over the functions of injured parts) and mass action (the involvement of large
areas of the brain
in functioning as a whole in order to carry out complex functions)
○ Done on animals
● Electrodes
○ small wires used to electrically stimulate biological tissues or measure
electrical activity in these tissues
○ If an electrode is placed on or into a specific area of the brain and stimulation
leads to a bodily response, it can be assumed that area of the brain is
responsible for that action
○ Wilder Penfield used electrodes to understand epilepsy as he sought to
remove the sections of the brain that contributed to seizures. He used
electrodes to locate the abnormally functioning brain tissue, by recording the
responses of his patients who were conscious. As a result, he and his
colleagues created a brain map
Neuroimaging (1890s - now)
● captures an image of the brain
● Structural neuroimaging techniques are MRI and CT → obtain images of the
anatomy of the brain
● Functional neuroimaging techniques are PET and fMRI captures an image of the
brain → view the brain ‘live’ during a response and provide information about both
function and structure
● CT
○ combines a series of x-ray images taken from different angles to create
cross-sectional images of the body
○ The patient may be required to take or be injected with
a substance referred to as ‘contrast’. Helps to make certain structures more
visible, thereby assisting with the interpretation of the images.
