Transcript The Brain.

Chapter 4 – The Brain
•Evolution
•Baby Theresa
•Brain Injury
•Play Dough Brains revisited
•The Brain
•Cortex/Four Lobes
•Hemispheres – Left and Right
•Fore Brain
•Mid Brain – Limbic System
•Hind Brain
Evolution(p. 69)
Baby Theresa (p.74)
Infants born with anencephaly have either a severely
underdeveloped brain or total brain absence. A portion
of the brain stem usually protrudes through the skull,
which also fails to develop properly. (Gale Group)
Baby Theresa II
The infants are kept alive by the
developed midbrain and the hindbrain.
The medulla is key in maintaining life.
The Brain
Thalamus
Cerebrum
(Cortex)
Corpus callosum
Hypothalamus
Pituitary gland
Cerebellum
Medulla
Cortex (Cerebrum)
Neurons and Glials
The Neurons make up the outside layers
of the cortex. The wrinkles that are made
on the brain are wrinkles in the Neuron
layer of the cortex.
Making the damage to the outside layer
(concussion/injury) ever present
The Glial cells are under the Neurons.
Functions of the cortex are localised into discrete areas:
Sensory Areas- these receive impulses via sensory neurones
from receptors that detect the stimuli reaching the body. The
skin has more receptors in some parts of the body than others.
Motor areas send impulses to skeletal muscles along nerve
fibres passing down the brain stem and spinal cord. As with the
sensory areas the part of the body is represented by an area of
the motor cortex.
 Association areas make decisions and send impulses
through the motor areas.
The Lobes
Prefrontal
Lobe
Frontal Lobe p.74
Function: This lobe is divided into three different areas and is
responsible for cognition, memory and emotional intelligence.
Prefrontal Area – This area is responsible for planning, complex
ideas, behaviors, concentration and the ability to focus. This
area is also responsible for emotional traits, judgment and
inhibition.
Motor – The rear-most portion of the frontal lobe, this area is
responsible for voluntary motor activity.
Premotor –This area is involved with volitional movement
(storage of motor patterns) and motor activity to the opposite
side of the body. In other words, the right side of the brain is
responsible for the left side of the body.
Frontal Lobe Injury
Injury to this area, or a lack of
accurate sensory information from
the lower levels of the brain, causes
among other things: inability to
retrieve recent memories,
inattentiveness, lack of focus,
difficulty learning new information,
lack of inhibition, and inappropriate
sexual and social behavior.
Frontal Lobotomy
Was a surgical procedure in which
about one-third of the frontal part of
the frontal lobe was cut away from the
rest of the brain.
This was to help those people with
sever emotional problems.
18,000 done in the 1940s and 1950s.
Frontal Lobotomy
Follow the link to
learn more about
prefrontal lobotomies
http://www.answers.com/topic/lobotomy-1
Temporal Lobe
This lobe is responsible for receiving auditory information and
recognizing words; it is thus central to the process of learning
and understanding language. It is also an important structure for
emotions, for making new memories, and for short-term
memory. Other parts of this lobe appear to integrate memories
of taste, sound, sight, and touch.
Injury to the temporal lobe, or a lack of accurate sensory
information from the lower levels of the brain, impairs the
ability to process auditory information accurately, as well as
other hearing impairments. Injury to this area can also
cause a person to become overly agitated or irritable, and
to exhibit childish behavior.
Parietal Lobe
This lobe is responsible for processing sensory input and
sensory discrimination. It is also called the ‘association
area’. It is responsible to receive and utilize from the lower
levels of the brain, information about: temperature, taste,
touch, and movement from the rest of the body – such as
distance and position of objects. It is also responsible for
reading and arithmetic.
Injury to this area, or lack of accurate sensory
information from the lower levels of the brain, create an
inability to discriminate between different stimuli, locate
and recognize parts of the body, inability to write and
disorientation in environmental space.
Occipital Lobe
This is the primary visual center of the brain. It processes
information from the eyes, and links that information with
images stored in memory. In other words, this area helps
you determine what you are looking at.
The most common effect of injury to the occipital
lobe is visual impairment; severe injury to this lobe
can cause blindness. Along with visual impairment,
injury to the occipital lobe can cause hallucinations,
can cause objects to appear larger or smaller than
they are, and can cause colors to appear abnormal.
 The visual sensory area is at the back of the brain and
receives sensory input from the optic nerve.
 Neurones from the left half of the retinas of both eyes go to
the visual sensory area in the left hemisphere and likewise for
the right half of the retina.
 Therefore the two hemispheres see slightly different images
from opposite sides of the visual field, these differences help
judge distance.
p. 76-79
Midbrain p.80
The Midbrain p.80
The Midbrain – is a sub cortical level of the
brain. Through the body of the midbrain pass
a substantial number of various fiber tracts
especially related to vision, voluntary muscle
activity and other important functions. The
midbrain contains:
Thalamus
Hypothalamus
Hippocampus
Basal Ganglia
Pineal Body
Corpus Callosum
Thalamus
Thalamus - A main sensory relay and integrative center connecting
with many areas of the brain, including the cerebral cortex.
Hypothalamus
Hypothalmamus – The master control of the autonomic nervous
system, parasympathetic and sympathetic. This system stimulates
and controls structures such as the heart, most glands and smooth
muscles. In effect, this system allows your systems to excite and
relax, as needed. This system integrates the autonomic and
endocrine functions with behavior.
Hippocampus
Hippocampus – This area of the brain, apart from its other
functions, is primarily responsible for short term memory.
Amygdala
(part of Basal Ganglia)
Amygdala –is involved in forming, recognizing, and remembering
emotional experiences, especially fear as well as emotional facial
expressions.
Hindbrain p.73
Pons
Pons—functions as a bridge to interconnect messages between
the spinal cord and brain. The pons also makes involved in sleep.
Medulla (Oblongata)
Medulla—located at the top of the spinal cord, including a group
of cells that control vital reflexes, such as respiration, heart rate
and blood pressure.
Cerebellum
Cerebellum—located in the back and under the brain. Involved in
coordinating movements but not in initiating voluntary movement.
Key in timed motor activities like sports
Hemispheres (Cortex) p. 87
Left – Right Brain …
Characteristics of Left Brain:
Logical
Sequential
Rational
Looks at parts
Analytical
Objective
In addition, this part likes
technicalities, numbers, data,
facts, logic and precision.
Characteristics of Right Brain:
Random
Intuitive
Subjective
Looks at wholes
Holistic
Synthesizing
This part is more interested in
challenge, risk, new ideas,
imagination, and whole picture.
Right Brain vs. Left Brain
http://www.news.com.au/dailytelegraph/story/0,22049,22535838-5012895,00.html
Split Brain Operation
Splitting the corpus callosum (the tissue connecting the left
and right halves of the brain – 200 million nerve fibers).
This is done especially with epileptic patients. It splits the
two halves into independent parts of the brain.
This takes some therapy to find out what each half can do.
Right Brained or Left Brained
When reading your left side actually
reads the words and allows you to
decode the words.
Your right side keeps track of the
story and visualizes the details and
recalls related personal experiences.
Both is the most likely answer.
 The upper part of the brain, the cerebrum is responsible for
all voluntary activities, it is connected to the nervous system.
 The cerebrum is divided down the middle by a deep cleft
into two cerebral hemispheres connected by the nerve fibres
of the corpus callosum
 The inside contains fluid and only the outer few mm of
the cerebral hemispheres contains neurones and this is called
the cerebral cortex.
 The cortex is highly folded providing a large surface area.
Parts of the brain in
relationship to your face …
MRI Brain Images p. 70
http://www.lahey.org/Medical/Radiology/MRI_CommonTypes_Brain.asp
MRI p. (70)
Magnetic resonance imaging
involves passing nonharmful
radio frequencies through the
brain.
MRIs are used to study the
structure of the brain.
PET Brain Scans (p. 71)
Positron emission tomography (PET) is a nuclear
medicine medical imaging technique which produces a
three-dimensional image or map of functional
processes in the body.
PET Scans (p. 71)
Done by injecting slightly
radioactive solution into the
blood and then measuring the
absorption by the brain.
Indicating the activity of
neurons.
Other uses of PET Scans
A normal PET scan which shows the difference in brain activity
between reciting a set of well memorized and practiced words; and a
set of words not practiced much.
PET scans of a schizophrenia
sufferer's brain (left) and normal
brain (right).
Other PET Scans
PET scans are used most often
to detect cancer and to examine
the effects of cancer therapy by
characterizing biochemical
changes in the cancer.
PET Scans can be
used to view
activity in other
parts of the body
Divisions of the Nervous System
Central Nervous
System
Somatic Nervous
System
Network of nerves to
move voluntarily
Sympathetic Division
Triggered by a threat
Peripheral Nervous System
Automatic Nervous
System
Regulates heart rate,
breathing, blood pressure
without conscience effort
Parasympathetic Division
Returns body to calmer/relaxed
state
Sympathetic Nervous System
Autonomic nervous system
is triggered by a
threatening or challenging
physical stimuli –
=Increases blood pressure
=dilate pupils
=heightened physiological
Autonomic Nervous System p.81
Regulates Physiological responses to stimuli
Sympathetic Nervous System-Fight or Flight
response to stimuli
Parasympathetic Nervous System-Relaxed
state (Often following a stressful period or
event)
Parasympathetic Nervous System
Decreasing physiological arousal and calming
your body down. The body triggers the
hypothalamus
Homeostasis
Homeostasis means that sympathetic and
parasympathetic systems work together to
keep the body’s level of arousal in balance
for optimum functioning.
Amygdala
Amygdala – limbic structure
involved in many brain functions,
including emotion, learning and
memory. It is part of a system
that processes "reflexive"
emotions like fear and anxiety.
Cerebellum
Cerebellum – governs movement.
Coordinates (but not initiates)
voluntary movement.
Cortex/Cerebrum
Cortex or Cerebrum – are the four
lobes of the “gray” matter. It is dived
unto four major lobes and is the part
of the brain used in high level brain
activities.
Frontal Lobe
Frontal Lobe – helps control
skilled muscle movements,
mood, planning for the future,
setting goals and judging
priorities.
Hippocampus
Hippocampus –
plays a significant
role in the
formation of longterm memories.
Medulla (Oblongata)
Medulla (Oblongata) – contains
centers for the control of vital
processes such as heart rate,
respiration, blood pressure, and
swallowing.
Limbic System
Limbic system – a group of
interconnected structures that
mediate emotions, learning and
memory.
Occipital Lobe
Occipital Lobe –
helps process
visual information.
Parietal Lobe
Parietal Lobe – receives and
processes information about
temperature, taste, touch, and
movement coming from the rest of
the body. Reading and arithmetic
are also processed in this region.
Pons
Pons – contains centers for the
control of vital processes,
including respiration and
cardiovascular functions. It also is
involved in the coordination of
eye movements and balance.
Thalamus
Thalamus – a major relay station
between the senses and the cortex
(the outer layer of the brain
consisting of the parietal, occipital,
frontal and temporal lobes).
Temporal Lobe
Temporal Lobe – processes
hearing, memory and language
functions.
The Different Regions of
the Brain
 The medulla controls heart rate, breathing, peristalsis,
and reflexes such as sneezing.
 The hypothalamus controls temperature and water
homeostasis. Also controlling the release of hormones
by the pituitary gland.
 The thalamus is a relay station, integrating sensory
input and channelling it to the sensory areas of the
cerebrum.
 The cerebellum co-ordinates muscle movement and so
controls balance, posture and movement.
 The main motor area controls the main skeletal muscles of the
body and the main sensory area receives input from the various
skin receptors all over the body.
 The areas are duplicated onto the two cerebral hemispheres,
which control opposite sides of the body.
 Therefore, those situated on the left cerebral hemisphere are
linked to the right side of the body and vice versa.
 The regions of the body with many sensory neurones have
correspondingly large areas of the cortex linked to them. For
example, the lips occupy a larger region of the sensory cortex
than the shoulder, because they have more sensory neurones.
Theses are involved in advanced kills such as visual
recognition , language understanding, speech and memory
retrieval.
 The frontal lobes are particularly large in humans, they
are thought to responsible for higher functions such as
abstract thought, personality and emotion.
 The association areas are not duplicated in the two
hemispheres. The right hemisphere has association area for
face recognition, spatial skills and musical sense. The left
hemisphere has association areas for speech language and
language mathematical logical and analytical