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Biological Bases of Behavior
The Nervous System
The Hindbrain
Neurons
The Midbrain
2 Categories
The Forebrain
3 Kinds
Right/Left Hemisphere
Anatomy of a neuron
Plasticity in the brain
Communication
The Endocrine system
Neurotransmitters
Heredity and behavior
CNS/PNS
Agonist/Antagonist
The Brain
The Limbic system
• GABA is a major inhibitory neurotransmitter in
the brain. A lack of GABA can lead to
involuntary motor actions, including tremors
and seizures. Alcohol stimulates the release of
GABA. Low levels of GABA produce anxiety,
and GABA agonists (tranquilizers) are used to
reduce anxiety.
• Glutamate is the most common
neurotransmitter, it’s released in more than
90% of the brain’s synapses. Glutamate is
found in the food additive MSG…excessive
glutamate can cause overstimulation,
migraines and seizures.
The Central and Peripheral Nervous Systems
• What components make up the CNS?
• The brain and spinal cord
• What are the two systems that comprise the
PNS?
• The somatic and the autonomic
• What are the two components that comprise
the autonomic?
• The sympathetic and the parasympathetic
The Nervous System
The Brain, The Hindbrain
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The hindbrain is located at the skull’s rear
The hindbrain is the lowest portion of the brain
There are three parts of the hindbrain…
The medulla
Helps controls life sustaining behaviors
The cerebellum
Plays pivotal roles in motor coordination
The pons
A bridge in the hindbrain involved in sleep and
arousal and also plays a role in movements of the
body such as walking and balance.
The Brain, The Midbrain
• The midbrain is located between the hindbrain and forebrain
• Nerve fibers ascend and descend to connect the higher and lower
portions of the brain and contains areas that are concerned with
integrating sensory processes
• The midbrain contains the reticular formation
• The reticular formation is a collection of neurons involved in
behaviors such as walking, sleeping, sex, and reacting. The reticular
formation is also responsible for filtering out stimuli that are
coming into the brain from the spinal cord and to relay the
remainder of the signals to other areas of the brain.
• When electrical stimulation is applied to the reticular formation of
an animal, the animal becomes fully awake, when severed, the
animal falls into a deep coma
• The midbrain also consists of small groups of neurons that use the
neurotransmitters serotonin, dopamine, and norepinephrine
• They send signals to a variety of brain regions and are why they are
involved in higher level and integrative functions
The Brain, The Forebrain
• The forebrain is the largest and most complex region of the
brain
• What are the components that make up the forebrain?
• The thalamus, the hypothalamus, the limbic system, and
the cerebrum
• The thalamus is referred to as the relay station and is
involved in integrating and filtering information and
relaying some of the remaining signals to higher brain
levels
• The hypothalamus is involved in the regulation of basic
biological needs
• The limbic system regulates emotion, especially pleasure
centers and includes the thalamus, the hypothalamus, the
hippocampus, and the amygdala
• The cerebrum is the largest and most complex part of the
human brain divided into 2 parts the left and right
hemispheres
The Brain
The Cerebral hemisphere
• The cerebral hemisphere is
• divided by lobes
• The occipital lobe is at the back of the head
and is responsible for visual signals
• The parietal lobe registers the sense of touch
• The temporal lobe contains areas responsible
for auditory processing and when damaged,
people experience the inability to
comprehend speech and language, or aphasia
• Broca’s aphasia…people find it difficult or
impossible to produce speech, but can
comprehend speech (verbal/spoken)
• Wernicke’s aphasia…people can speak, but they
have difficulty finding the correct words and have
difficulty comprehending written or spoken
communication
• Mirror neurons are neurons that are activated by
performing an action or by seeing another or
person perform the same action
Front Part Of The brain
Plasticity in the Brain
• What is plasticity?
• Plasticity is descriptive of the brain because of its ability to
change and adapt can be functional plasticity or structural
• Structural plasticity-when presented with new learning
opportunities, the brain’s structure will change in an effort
to adapt to the new processes… the hippocampus of New
York cab drivers
• Functional plasticity-when areas of the brain have
sustained damage that affects incoming sensory pathways,
the brain will reorganize the neural pathways, in blind
people, areas in the occipital lobe will assist in verbal
processing
• Plasticity is limited and declines with age…“use it or lose it”
Right/Left Brain
• The left hemisphere of the brain controls the right side
of the body and contains areas dedicated to logic,
reasoning, analysis, and language
• The right hemisphere controls the left side of the body
and contains brain areas dedicated to emotional and
creative impulses
• Lateralization allows for information to be shared
between the hemispheres
• In split-brain surgery, the corpus callosum is cut to
reduce the severity of epileptic seizures only done in
cases in which the patient doesn’t respond to other
treatment…split brain study
The Endocrine System
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The endocrine system consist of glands that secrete chemical messengers into the bloodstream to
help control bodily functions
The messengers are called hormones
What are hormones?
Hormones are the chemical substances released by the endocrine glands
The endocrine system is controlled by the nervous system through the hypothalamus
The hypothalamus works in concert with the pituitary gland
The pituitary gland (master gland) releases a great variety of hormones that extend throughout the
body, stimulating actions in other endocrine glands
The endocrine system is involved in the fight-or-flight response
Too much stress may also suppress the process of neurogenesis in the hippocampus
In times of stress, the hypothalamus sends signals along two pathways…
the autonomic and through the pituitary gland----adrenal glands
Then the adrenal glands secrete hormones throughout the body in preparation for the emergency
Too much stress can suppress the immune response system, making the person vulnerable to
diseases
Testosterone is a male sex hormone produced by the testes
Women secrete small amounts of testosterone from the adrenal cortex
There are positive correlations between testosterone levels and aggression in both men and
women
Testosterone levels-aggression??? Aggression-testosterone levels???
There are correlations between testosterone and cognitive abilities
But for older adults, higher testosterone levels are predictive of higher scores on memory,
information processing, and spatial abilities
The Evolutionary Bases of Behavior
• Darwin and natural selection
• Adaption is an inherited characteristic,
because of natural selection...it occurs slowly,
gradual, lingering in a population…humans
show a taste for fatty foods, but we no longer
need to intake lots of calories