Transcript Biological Bases Of Behaviour

Biological Bases Of Behaviour
Central Nervous System
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Consists of the brain and the spinal cord
The spinal cord connects the brain to the
peripheral nervous system
Cerebral Cortex
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Is the thin, folded covering of the cerebrum.
The cerebrum is the largest part of the brain
and consists of two halves called the cerebral
hemispheres
Corpus callosum
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The structure consisting of about 200 million
nerve fibres that provide communication
between the left and right hemispheres of the
brain
Frontal Lobe
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Consists of the primary motor cortex which is
responsible for generating movement of body parts.
Specific points are responsible for certain parts of the
body (motor homunculus)
The association area is involved in expressing
emotional behaviour, personality and temperament
Broca’s area (only in left hemisphere!) is responsible
for the production of clear, articulate speech, as well as
with analysing the grammatical structure of sentences
Parietal Lobe
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Contains the somatosensory cortex, which is
responsible for registering sense of touch, and
receives sensory information from sensory
receptors about touch, pain, pressure, muscle
movement and position.
Also responsible for integrating visual
information
Occipital Lobe
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Regions where visual information is received
and processed.
Visual association areas bring together both
visual information and information from other
areas of the cerebral cortex.
Enables us to form visual images of memories
and to think visually
Temporal Lobe
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Responsible for receiving and processing
sound.
Play an important part in our ability to
remember faces, and the storing of memories
such as events we have experienced.
Wernicke’s area (only in left lobe!) is
responsible for interpreting sound and
understanding speech. Also for locating
appropriate words when we speak or write
Hemispheric Specialisation
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The specialisation and dominance of certain
brain functions by each of the cerebral
hemispheres
Whilst certain hemispheres dominate, the
functions can still be taken over by the other
hemisphere if damage occurs (plasticity of
brain)
Functions of Left Hemisphere
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Verbal functions such as reading, writing,
speaking and understanding speech
Analytical functions such as mathematical
logic, analysing, organising and interpreting
data
Functions of the right hemisphere
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Non-verbal functions such as:
Recognising faces or music
Spatial tasks
Jigsaw puzzles
Producing/ appreciating art
daydreaming
Studies of people with damaged
brains
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Studies of brain damage by Paul Broca and
Karl Wernicke showed that separate areas
were responsible for language production and
language comprehension
Roger Sperry’s split brain surgery showed
that the left and right hemispheres were
dominant in different tasks (know the results of
his study!)
Studies of people with intact brains
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EEG- electroencephalograph
EMG- electromyograph
EOG- electro-oculargram
MRI- Magnetic Resonance Imaging
CAT- Computerised Axial Tomography
PET- Positron Emission Tomography
Spinal Cord
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Column of nerve fibres that run from the base
of the brain to the lower back region
31 pairs of nerves
White matter- solely bundles of axons which
are covered in myelin (myelin sheath)
Grey matter- contains cell bodies along with
their axons and dendrites and are located
mainly near the centre of the spinal cord.
How is sensory info transmitted
from the body to the brain?
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Sensory information is sent from the sensory
receptor cells in the PNS via sensory neurons
to the CNS
How is motor information sent from
the brain?
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Motor information leaves the brain via motor
neurons that depart the motor cortex
Message is transmitted via motor neurons
down the spinal cord to the skeletal muscles in
the body, the visceral muscles of the internal
organs or glands which secrete hormones
At their destination they connect to effector
cells which control movement or hormone
secretion
The Peripheral Nervous System
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Is comprised of all neurons outside of the
Central Nervous System
It provides the pathway from the brain and
spinal cord to all other parts of the body.
Is separated into the somatic and autonomic
nervous systems
Somatic Nervous System
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Has a sensory and motor function. Sensory function
is to transmit info to the brain from the sensory
receptors and the motor function involves moving
muscles attached to the body’s skeleton.
Involves controlling skeletal muscles that are involved
in movement
If the spinal cord is severed, the somatic nervous
system below the point of damage becomes paralysed
because the messages cannot bridge across.
Autonomic Nervous System
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The network of neurons connecting the CNS to our
internal muscles and organs. Controls non-skeletal
muscles such as the heart, kidneys, glands, etc.
The majority of functions occur without our control, but
we can gain control of some functions through
biofeedback. This is a process whereby an individual
receives feedback about a particular function and
learns techniques to control these functions, such as
meditation, relaxation, etc.
Has 2 sub-branches: Sympathetic and
parasympathetic nervous systems
Sympathetic Nervous System
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The branch of the ANS that provides the body
with a sudden burst of energy due to needing
to deal with a threatening or stressful situation.
Number of changes occur such as pupils
dilate, secretion of adrenalin, increased heart
rate, digestion decreases, etc.
Parasympathetic Nervous System
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Returns the body to a state of homeostasis
once threat or stressor has passed
Keeps the body in homeostasis (regulates
internal systems and minimises energy)
Physiological Systems Involved In
Arousal
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Arousal- an organisms state of alertness and
readiness for action
Fight-flight response- an automatic reaction
by the sympathetic N.S to prepare the body for
dealing with a physically or psychologically
threatening situation.
Polygraph
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A device that detects fluctuations in certain
physiological functions that are controlled by the
autonomic nervous system
Typically measures heart rate, respiration rate, blood
pressure and galvanic skin response
Person is asked control questions and relevant
questions, which are compared to assess arousal in
the participant
Limitations include similarity in arousal levels between
different emotions including lying, naturally low rates in
certain people, and the participant creating high
fluctuations on control questions. Produces too many
false hits
Effects of Prolonged or intense
arousal
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Stress- a condition involving psychological and
physiological tension that arises from internal
or external sources
Stressor- events or circumstances that cause
stress.
Stress may be acute or high in intensity, or
may be chronic.
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Physiological effects- fatigue and lowered
immune system
Psychological effects- 3 categories;
behavioural effects (shaky hands, jumpiness,
furrowed brow), emotional effects (feelings of
anger, depression, helplessness, irritability)
and cognitive effects (forgetfulness, inability to
concentrate or make decisions)
General Adaptation Syndrome
(Hans Seyle)
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A pattern of physiological responses an
organism experiences when placed under
intense or prolonged stress
Consists of 3 identifiable stages
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Alarm reaction- first aware of stressor. Temporary
state of shock as if injured, but quickly recovers as the
sympathetic N.S is activated (countershock). Flightfight is activated.
Resistance- resistance to stressor rises above normal
level. Cortisol is released to help repair tissue, but
presence lowers immune system
Exhaustion- extreme fatigue, high anxiety and
depression. Illness due to low immune system.
Relationship between stress and
disease
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A psychosomatic illness is one in which the
physical symptoms are caused or heightened
by psychological factors. It is not imagined.
Conditions identified include arthritis, asthma,
chronic back pain, colds, diabetes, headaches,
migraines, menstrual discomfort, stomach
ulcers, ulcerative colitis, cancer, heart disease
and multiple sclerosis.