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The Biological Basis of Behavior
The Nervous System
 The Nervous system is living tissue composed of cells.
The cells in the nervous system are composed of
Neurons and glia cells.
 Neurons are individual cells in the nervous system
that receive, integrate, and transmit information.
 Glia cells are found throughout the nervous system .
They provide nourishment to the neurons, help remove
waste products and provide insulation around many
axons. The out number neurons in ten to one.
Parts of the Neuron
 The Soma is the cell body containing most of the
chemical machinery in the neuron.
 Dendrites are part of the neuron which receive
information, information flows into the soma. The
information then travels away from the soma and along
the axon.
 The Axon is a long thin fiber that transmits
information from the soma to other neurons or muscle
glands. Axons are covered with myelin sheaths.
Parts of the Neuron
 The Myelin Sheath is a fatty, whit insulating material which
covers the axons and speeds up transmission between
neurons.
 Terminal buttons are at the end of axons and are small
knobs that secrete chemicals called neurotransmitters.
 Synapses are junctions where information is transmitted
from one neuron to another . This is where neurons meet ,
however they do not actually touch.
 The neurons meet at the synaptic cleft. The synaptic cleft
is the microscopic gap between the terminal button of one
neuron and the cell membrane of another neuron.
The Neuron
Classification of Neurons
 Sensory Neurons send signals to the CNS.
 Motor Neurons send signals away from
CNS.
 Interneuron's collect signals within cells.
Neurotransmitters
 Neurotransmitters are chemicals that act
as messengers that may activate neighboring
neurons. Neurotransmitters are
fundamental to behavior, playing a key role
in everything from muscle movement to
moods and mental health.
Neurotransmitters and
Behavior
 Acetylcholine (Ach)- attention, memory, and arousal
 Dopamine (DA)- voluntary movement
 Norepinephrine (NE)- mood and arousal
 Serotonin- sleep, wakefulness, eating and aggression
 GABA- anxiety, sleep and arousal
 Glutamate- learning and memory
 Endorphins- pain relief and stress
Communication of Neurons
Presynaptic neurons sends signal to postsynaptic
neuron.
 Messages travel across the gaps between neurons
with the arrival of an action potential and the
terminal buttons trigger the release of
neurotransmitters.
 EPSP is an excitatory postsynaptic neuron with
positive voltage which increases the likelihood the
neuron will fire an action potential.
 IPSP is an inhibitory neuron in which there is a
negative voltage and decreases the likelihood the
neuron will fire an action potential.
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Communication of neurons
Neuron Resting Potential and Action
potentials
 A neuron at resting potential is at a stable negative
charge of about -40mv to -90mv, typically averaging
about a -70mv charge. The neuron is inactive at
resting potential and contains chloride ions.
 An Action Potential is a brief shift in the neurons
electrical charge that travels along an axon. During
an action potential the charge of the neuron becomes
positively charged to about +50mv. During this time
the chloride ions flow out of neuron and sodium
neurons flow into the cell. A neuron will either fire or
not, this is called the “All or Nothing Law”.
The Nervous System
 The Nervous System is divided into two different parts. The two
parts of the nervous system are the Central Nervous System
(CNS) and the Peripheral Nervous System (PNS).
 The CNS is the brain and the spinal cord.
 The PNS is the cranial and spinal nerves . The PNS contains both
sensory and motor neurons. Motor neurons in the PNS are
divided into two systems. These two systems are the somatic
nervous system, which is the voluntary part of the PNS and the
autonomic nervous system, which is the involuntary part of the
PNS.
 The Autonomic Nervous System (ANS) is divided into two parts.
These two parts are the sympathetic nervous system (“flight or
fight”) and the parasympathetic nervous system (rest).
The Nervous system
The Hindbrain
 Medulla oblongata - Attaches to the spinal cord,
controls largely unconscious but essential
functions, such as; breathing, maintaining muscle
tone, and regulating circulation.
 Brainstem- is the region of the brain that connects
the cerebrum with the spinal cord. Motor and
sensory neurons travel through the brainstem
allowing for the relay of signals between the brain
and the spinal cord.
The Hindbrain
 Pons- Bridge of fibers that connects the brainstem
with the cerebellum. The pons also contains several
clusters of cell bodies involved with sleep and arousal.
The Hindbrain
 Cerebellum- Also called the “little brain” that is
involved in the coordination of movement and is
critical to the sense of equilibrium, or physical balance.
The Midbrain
 The Midbrain- segment of brainstem that lies between
hindbrain and forebrian.
 Reticular formation -Contributes to functions of
muscles reflexes, breathing and pain perception. It is
best known for its regulation of sleep and wakefulness.
The Forebrain
The Forebrain
 Thalamus- all sensory information (except
smell) must pass through this structure to
reach the cerebral cortex. It is the relay
station for incoming and out coming signals.
The Forebrain
 Hypothalamus - involved in the
regulation of biological needs. The
hypothalamus lies beneath the
thalamus. It is responsible for
regulating the needs of; hunger, thirst,
and temperature control.
The Forebrain
Hippocampus- part of the limbic
system involved in learning and
memory. It appears to contain
emotion “pleasure centers”.
The Forebrain
Amygdala- part of the limbic
system involved in emotion and
aggression. The “Fear Center” in the
brain.
The Forebrain
 Corpus Callosum- bridge of fibers passing information
between the two cerebral hemispheres.
The Forebrain
 Cerebrum- the largest and most complex part of the
human brain. It is responsible for our most complex
mental activities, including learning, remembering,
thinking and consciousness.
The Forebrain
 Cerebral Cortex- is divided into right and left
hemispheres. It encompasses about two-thirds of the
brain mass and lies over and around most of the
structures of the brain. It is the most highly developed
part of the human brain and is responsible for
thinking, perceiving, producing and understanding
language. It is also the most recent structure in the
history of brain evolution.
Language areas in the brain
 The brain is divided into two halves, a left
hemisphere and a right hemisphere.
 In human beings, it is the left hemisphere that
usually contains the specialized language
areas. While this holds true for 97% of righthanded people, about 19% of left-handed people
have their language areas in the right hemisphere
and as many as 68% of them have some language
abilities in both the left and the right hemispheres.
The Brain’s Association areas
Broca’s Area
 The first language area within the left hemisphere to be discovered is called Broca's Area,
after Paul Broca. Broca was a French neurologist who had a patient with severe language
problems: Although he could understand the speech of others with little difficulty, the
only word he could produce was "tan.“
 After the patient died, Broca performed an autopsy, and discovered that an area of the
frontal lobe, just ahead of the motor cortex controlling the mouth, had been seriously
damaged. He correctly hypothesized that this area was responsible for speech
production.
 Physicians called the inability to speak aphasia, and the inability to
produce speech was therefore called Broca's aphasia, or expressive
aphasia. Someone with this kind of aphasia has little problem
understanding speech. But when trying to speak themselves are capable
only of slow, laborious, often slurred sequences of words. They don't
produce complete sentences, seldom use regular grammatical endings such
as -ed for the past tense, and tend to leave out small grammatical words.
Broca’s and Wernicke’s Area
Wernicke’s Area

The second language area to be discovered is called Wernicke's Area, after Carl
Wernicke, a German neurologist. Wernicke had a patient who could speak quite well, but
was unable to understand the speech of others. After the patient's death, Wernicke
performed an autopsy and found damage to an area at the upper portion of the temporal
lobe, just behind the auditory cortex. He correctly hypothesized that this area was
responsible for speech comprehension.
 This kind of aphasia is known as Wernicke's Aphasia, or receptive aphasia. When you
ask a person with this problem a question, they will respond with a sentence that is more
or less grammatical, but which contains words that have little to do with the question or,
for that matter, with each other. Strange, meaningless, but grammatical sentences come
forth, a phenomenon called "word salad."
 Like Broca's area is not just about speech production, Wernicke's is not just about speech
comprehension. People with Wernicke's Aphasia also have difficulty naming things, often
responding with words that sound similar, or the names of related things, as if they are
having a very hard time with their mental "dictionaries."
Brain Plasticity
 Brain Plasticity is the ability of the brain to change
through 1) experience 2) damage to incoming sensory
pathways or destruction of brain tissue can lead to
neural reorganization and 3) the adult brain can
generate new neurons, a process called neurogenesis.
 Brain Plasticity shows the brain is flexible and
constantly evolving.
The Endocrine System
 The Endocrine System consists of glands that secrete
chemicals into the bloodstream that help control
bodily functioning.
 Hormones are the chemical substances released by
the endocrine glands. Most of the endocrine system is
controlled by the nervous system through the
hypothalamus.
The Endocrine System
The Endocrine Glands
 The Pituitary gland secretes growth hormones and regulates
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secretions of thyroid gland, pancreas, adrenal cortex, and gonads.
It is the “master gland” of the endocrine system, however the real
power behind it is the hypothalamus.
The Pancreas secretes insulin and glucagon to regulate sugar
metabolism.
The Thyroid gland regulates metabolic rates.
The pineal gland is an endocrine gland, like the pituitary gland, it
secretes a hormone -- melatonin.
The Adrenal glands consist of the Adrenal cortex Affects (salt
and carbohydrate metabolism and inflammatory reactions) and
the Adrenal medulla (sleep and emotional arousal).
The Gonads are the Ovaries and the Testes which secrete sex
hormones.
Brain Imaging Techniques
Magnetic Resonance Imaging (MRI) is a sophisticated software
system called Computerized Tomography (CT) converts this
information into a three-dimensional picture of any part of the body. A
brain scan taken this way looks like a grayish X-ray, the different, clearly
delineated types of tissue.
Brain Imaging Techniques
 Functional MRI (fMRI) is a brain imaging technique in which neuronal firing is
fueled by glucose and oxygen, which are carried in blood. When an area of the
brain is fired up, these substances flow towards it, and fMRI shows up the areas
where there is most oxygen. The brain takes about half a second to react to a
stimulus, so this rapid scanning technique can clearly show the ebb and flow of
activity in different parts of the brain as it reacts to various stimuli or
undertakes different tasks. fMRI is proving to be the most rewarding of
scanning techniques, but it is phenomenally expensive and brain mappers often
have to share a machine with clinicians who have more pressing claims to it.
Brain Imaging Techniques
Positron Emission Topography (PET) is a technique that achieves a
similar end result to fMRI -- it identifies the brain areas that are
working hardest by measuring their fuel intake. The pictures produced
by PET are very clear (and strikingly pretty) but they cannot achieve
the same fine resolution as fMRI. The technique also has a serious
drawback in that it requires an injection into the bloodstream of a
radioactive marker.
Brain Imaging Technique
An electroencephalogram (EEG) is a test used to detect
abnormalities related to electrical activity of the brain. This
procedure tracks and records brain wave patterns. Small
metal discs with thin wires (electrodes) are placed on the
scalp, and then send signals to a computer to record the
results. Normal electrical activity in the brain makes a
recognizable pattern. Through an EEG, doctors can look for
abnormal patterns that indicate seizures and other
problems.