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Chapter 1

PSY318H5 Chapter Notes - Chapter 1: Central Nervous System, Traumatic Brain Injury, Temporal Lobe


Department
Psychology
Course Code
PSY318H5
Professor
Ayesha Khan
Chapter
1

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Chapter 1: The Development of Neuropsychology
Traumatic Brain Injury (TBI) a wound to the brain that results from a blow to the head. Of these patients,
235, 000 are hospitalized and 50, 000 die.
Memory and attention are abilities that are required for effectively dealing with everyday problem
solving, a mental skill referred to as executive function. Thus L.D. (from case study) was able to
play golf – because it require that he deal with only one act at a time – but he cannot prepare a
meal – because doing so requires that he keep track of a number of things at the same time.
Neuropsychology: the study of the relation between behaviour and brain function. It draws information
from many disciplines: anatomy, biology, biophysics, ethology, pharmacology, physiology, physiological
psychology, and philosophy among them.
Its central focus is to develop a science of human behaviour based on the function of the human
brain.
Neuropsychology is strongly influenced by two traditional foci of experimental and theoretical
investigations into brain function: the brain hypothesis, the idea that the brain is the source of
behaviour, and the neuron hypothesis, the idea that the unit of brain structure and function is the
neuron, or nerve cell.
The Brain Hypothesis:
What is the Brain?
Brain is an Old English word for the tissue found within the skull.
The brain has two almost symmetrical halves called hemispheres, one on the left side of the body
and the other on the right.
Taken as a whole, the basic plan of the brain is that of a tube filled with salty fluid called
cerebrospinal fluid (CSF) that cushions the brain and may play a role in removing metabolic
waste. Parts of the covering of the tube have bulged outward and folded, forming the more
complicated looking surfaces structures.
The most conspicuous outer feature of the brain is the crinkled tissue that has expanded from the
front of the tube to such an extent that if folds over and covers much of the rest of the brain. This
outer layer is the cerebral cortex: layer of gray matter on the surface of the cerebral hemispheres
and composed of neurons and their synaptic connections, which form from four to six sublayers.
The folds of the cortex are called gyri, and the creases between them are called sulci. Some large
sulci are called fissures, such as the longitudinal fissure that divides the two hemispheres and the
lateral fissure that divides each hemisphere into halves
The cortex of each hemisphere is divided into four lobes, named after the skull bones beneath
which they lie. The temporal lobe is found laterally on the head, below the lateral sulci adjacent to
the temporal bones. Lying immediately above the temporal lobe is the frontal lobe: all the
neocortex forward of the central sulcus. It is located at the front of the brain. The parietal lobe is
the general region of the brain lying beneath the parietal lobe. The occipital lobe is the general
area of the cortex lying in the back part of the head.
The brains hemispheres are connected by pathways called commissures, the largest of which is the
corpus callosum: the fiber system connecting the homotopic areas of the two hemispheres. A
split-brain patient is one whose corpus callosum has been severed.
The cerebral cortex constitutes most of the forebrain, so named because it developsfrom the front
part of the tube that makes up an embryo’s primitive brain.
The remaining “tube” underlying the cortex is reffered to as the brain stem. The brainstem is in
turn connected to the spinal cord, which descends down the back in the vertebral column.
The forebrain mediates cognitive functions; the brainstem mediates regulatory functions such as
eating, drinking, and moving; and the spinal cord is responsible or sending commands to the
muscles.
Neuropsychologists commonly refer to functions performed in the forebrain as higher functions
because they include thinking, perception and planning.
How is the Brain Related to the Rest of the Nervous System?

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The brain and spinal cord together encased in bones are called the central nervous system (CNS).
CNS is connected to the rest of the body through nerve fibers.
Some nerve fibers carry information away from the CNS, and others bring information to it. These
fibers constitute the peripheral nervous system (PNS). CNS does not regenerate tissue, but PNS
does.
Nerve fibers that brings information to the CNS are extensively connected to sensory receptors on
the body’s surface, to internal body organs, and to muscles, enabling the brain to sense what goes
on in the world around us and within our bodies. Organized into sensory pathways, collections of
fibers carry messages for specific sensory systems for specific sensory systems, such as hearing,
vision, and touch.
These pathways carry information collected on one side of the body mainly to the cortex in the
opposite hemisphere by means of a subdivision of the PNS called construct somatic nervous
system (SNS).
Motor pathways are the groups of nerve fibers that connect the brain and spinal cord to the
body’s muscles through the SNS. The parts of the cortex that produce movement mainly use
motor pathways to muscles on the opposite side of the body.
The pathways that control these organs are a subdivision of the PNS called the autonomic
nervous system (ANS).
Figure 1.2:
The Brain Versus the Heart:
Alcmaeon of Croton (500B.C.) located mental processes in the brain and so subscribed to the
brain hypothesis. Emedocles of Acragas (490-430 B.C) located them in the heart and so
subscribed to what could be called the cardiac hypothesis.
Hippocrates (460-377 B.C.) and Galen (A.D. 129-199), influenced by their clinical experience,
described aspects of the brain’s anatomy and argued strongly for the brain hypothesis.
oGalen worked for 5 years to point out that brain damage impairs function, but also that
the nerves from the sense organs go to the brain and not to the heart. He also noted that
pressure on the brain causes cessation of movement and death, whereas pressureon the
heart causes pain but does not arrest voluntary behaviour.
Aristotle: The Mind
Aristotle (38-322 B.C.) was the first person to develop a formal theory of behaviour. He proposed
that a nonmaterial psyche was responsible for human thoughts, perceptions, and emotions and for
such processes as imagination, opinion, desire, pleasure, pain, memory and reason. It worked
through heart.
oAdopted by Christianity in its concept of the soul.
o“Mind” = memory and “psyche” = mind
The philosophical position that a person’s mind is responsible for behaviour is called mentalism,
meaning “of the mind”.
oInfluenced sensation, perception, attention, imagination, emotion, memory and volition
Descartes: the Mind-Body Problem
Rene Descartes (1596-1650), a French anatomist and philosopher who described a relation
between the mind and the brain.

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Described as nonmaterial and without spatial extent, the mind, as Descartes saw it, was different
from the body. The body operated on principles similar to those of a machine, but the mind
decided what movements the machine should make.
oDescartes located the site of action of the mind in the pineal body, small structure high in
the brainstem. This was based on the logic that the pineal body is the only structure in the
nervous system not composed of two bilaterally symmetrical halves and moreover that it
is located close to the ventricles.
oDescartes’ Concept of Reflex Action: in this mechanistic depiction of how Descartes
thought physical reflexes might work, heat from the flame causes a thread in the nerve to
be pulled, released ventricular fluid through an opened pore. The fluid flows through the
nerve, causing not only the foot to withdraw but the eyes and head to turn to look at it,
the hands to advance, and the whole body to bend to protect it. Descartes applied the
reflex concept to behaviours that today are too complex to be reflexive, whereas he did
not conceive of behaviour described as reflexive today.
Today, the pineal body, known as the pineal gland is thought to take part in controlling
biorhythms. Furthermore the cortex became much more central to understanding behaviour.
The position that mind and body are separate but can interact is called dualism, to indicate that
behaviour is caused by two things.
Descartes’ dualism originated what came to be known as the mind-body problem: for Descartes a
person is capable of being conscious and rational only because of having a mind, but how can a
nonmaterial mind produce movements in a material body?
oBody can affect the mind but the mind cannot affect the body avoid problem; body
function is parallel
Other philosophers called monists avoid the mind-body problem by postulating that the mind and
body are simply a unitary whole
Descartes proposed that animals, children (mind develops at age 7, with reason and talk) and
mentally ill (lost their minds) do not have minds and are machinelike.
Darwin and Materialism:
Materialism is the idea that rational behaviour can be fully explained by the working of the
nercous system without any need to refer to a nonmaterial mind. The perspective had its roots in
the evolutionary theories of Alfred Russell Wallace and Charles Darwin.
Studied organisms and their similarities in structure.
Darwin believed that all living things are said to have common descent, a unknown ancestor that
lived in the remote past.
The nervous system is one such common characteristic. It is an adaptation that emerged only once
in animal evolution. The same goes for the brain; all animals with brains evolved from an ancestor
with a brain.
Experimental Approaches to Brain function:
Localization of Function:
The first general theory to present the idea that different parts of the brain have different functions
was developed by German anatomist Franz Josef Gall (1758-1828) and his partner Johann Casper
Spurzheim (1776-1832). They proposed that the cortex and its gyri were functioning parts of the
brain and not just coverings for the pineal body. Through dissection they showed that the brain’s
most distinctive motor pathway, the corticospinal tract, leads from the cortex of each hemisphere
to the spinal cord on the opposite side of the body. Thus, they suggested, the cortex sends
instructions to the spinal cord to command movement of the muscles.
They also propose that the cortex is a functioning part of the brain, they also proposed that it
produces behaviour through the control of other parts of the brain and spinal cord through the
corticospinal tract.
Gall developed the localization of function: hypothetically the control of each kind of behaviour
by a different specific brain area.
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