Download NEUROBIOLOGICAL BASIS OF BEHAVIOR

NEUROBIOLOGICAL
BASES OF BEHAVIOR
MODULE 1
RNSG 2213
PART I
Anatomy and Physiology
Review
A & P Review
Three Main Parts of the Brain
1. Forebrain:
a. Cerebrum
b. Diencephalon
2. Midbrain
3. Hindbrain or Brain Stem
Cerebral cortex
“Gray matter”
The Forebrain
Cerebrum
Right and left hemispheres connected by the
corpus callosum
Lobes of the Cerebrum
The Lobes of the Cerebrum:
a Closer Look
• Frontal Lobe
– “The Executive” or decision maker;
regulation of behavior, e.g. planning,
adaptation to change, etc.
• Reliant on other parts of the brain
for data.
• Prefrontal area relates to features
of the personality, motivation & goal
setting
• Motor and Premotor areas:
voluntary movement
Lobes of the Cerebrum, cont’d
• Parietal Lobe
– Perception, interpretation, touch, body
perception
• Temporal Lobe
– Hearing
 Occipital Lobe
--Vision
The Forebrain: Cerebrum, cont’d
Limbic System
• “The Emotional Brain:”
– Consists of many structures
– Controls the “4 F’s”: Feeding, Fighting,
Fleeing and Fornicating
– Functions include Memory, Pleasure,
Emotions, Motivation
Functions of The Limbic System
More Functions of
Limbic System
• Olfactory Functions
• Feeding Functions
(consider the relationships between
emotions, pleasure, smell, and food
intake!)
Some Important Structures
Connecting to the Limbic System
• Hypothalamus-activates & controls many
body functions: endocrine, sleep, appetite,
body temp.
• Pineal Gland- role in sleep (secretes
melatonin) and consciousness
Important Structures Connecting to Limbic
System, cont’d
• Thalamus-association of sensory inputs with
pleasant and unpleasant feelings
• Hippocampus-memory processing, and making
of new memories
• Amygdala-stores feelings relating to memories,
Structures Connecting to Limbic System cont’d
• VTA (Ventral Tegmental Area) -midbrain
– “Pleasure pathway” or “Reward Center”
– Contains many dopaminergic neurons that
connect to sites in limbic system
– seat of craving in addiction
Important Structures
Connecting to the
Limbic System, cont’d
• Basal Ganglia or Extrapyramidal System
Regulate motor behavior, appropriate
muscle tone and posture
– Balances excitatory and inhibitory
neurotransmitters.
The Forebrain, cont’d
Diencephalon
– Connects the cerebrum with the lower brain
structures
– Relays sensory info. to cerebral cortex
(thalamus)
– Releases and inhibits hormones
(hypothalamus)
– Regulates fluid, temperature, GI, CV function
(hypothalamus)
The Midbrain
• Midbrain, or
Mesencephalon
--Responsible for
visual, auditory, and
balance reflexes and
posture
--Substantia Nigra
produces Dopamine
in this area
The Hindbrain & Brain Stem
• Hindbrain/Brain
Stem Structures
Pons: regulates respiration and muscle
tone
Medulla: reg. heart rate, blood pressure
Cerebellum: muscle tone and coordination
More (Hindbrain) Brainstem
Structures
• Reticular Formation- Integrates sensory
input
– Reticular Activating System-regulates
alertness and ability to pay attention (tune
out some stimuli); allows us to fall asleep
as well as wake up
A & P: Systems
• Autonomic Nervous System
– Sympathetic: Dominates in stressful
situations, prepares body for fight or flight
– Parasympathic: Dominates when person is
relaxed
Neurons: A Review
Nerve Tissue
• CNS: neurons, composed of:
– Cell body contains nucleus (genetic material)
– Axon transmits message to next cell
– Dendrites receive messages from cell
Neurons: Review, cont’d
Three classes of neurons in CNS
• Afferent (sensory)
• Efferent (motor)
• Interneurons
Neurons: Review, cont’d
• Synapse: the contact point between two
neurons.
• Synaptic Cleft: space between neurons
• Pre-synaptic neuron: area of axon where
neurotransmitters are stored.
• Postsynaptic neuron: area of dendrite
where receptor sites are located.
Neurotransmission =
Chemical Signalling
Neurotransmission (Physiology)
• Neurotransmitters are released into the
synaptic cleft (space) from the axon to the
dendrite.
(--Calcium ions facilitate NT release)
• NTs bind with receptors on post-synaptic
neuron (dendrite) and activate it
• Then NT substance is either deactivated or
returned to the axon (“reuptake”).
• Nerve cells can release more than one type of
neurotransmitter
Pre-synaptic and postsynaptic
neuron interchange
Neurotransmission Across the Synapse
Role of Neurotransmitters in
Mental Health
• Neurotransmitters
– Play an important role in human emotions and
behavior
– Influence motor activity and hormone levels
– Are the target for the mechanism of action for
psychotropic medications
Categories of Neurotransmitters
Cholinergics
• Acetylcholine (ACh): involved in
sleep, arousal, movement,
memory
Categories of Neurotransmitters, cont’d
MONOAMINES
• Norepinephrine: affects mood, cognition,
perception, locomotion, CV functioning, sleep
and arousal
• Dopamine: effects movement, coordination,
emotions, voluntary judgment, and release of
prolactin
Monoamines, cont’d
• Serotonin: effects sleep, arousal, libido,
appetite, mood, aggression, pain perception,
coordination, and judgment
• Histamine (role not well understood):
involved in the immune/inflammatory response
appears to be involved in mood
Categories of Neurotransmitters, cont’d
• Amino Acids
– Gamma Aminobutyric Acid (GABA)
functions as an inhibitory neurotransmitter
(“brain calmer”)
– Glutamate excitatory
Categories of NTs, cont’d
• Neuropeptides: endorphins and
enkephlins, modulate pain and reduce
peristalsis. Also called “natural or
endogenous opiates”
Neuroendocrinology
• Hypothalamus- the “master gland,” has direct
control over the pituitary
• Hormones: all of these affect health. Our main
focus in this course = TSH, Melatonin, ACTH
• Circadian Rhythms- implications in many
mental illnesses: affect sleep cycles and
regulate hormones which influence mood and
emotions.
Other Factors in Neurobiology
• Genetics: research has shown that all
major mental illness seem to have genetic
markers. (Increases “risk for”)
• Psychoimmunology: Normal immune
responses are decreased with acute and
chronic stress, grief, bereavement, and
depression.
PART 2
Neurobiology and
Mental Illness
Neurobiology and Mental Illness
• Neuroanatomical Changes
(examples)
-Enlargement of ventricles: schizophrenia,
alcoholism
-Atrophy of hippocampus: trauma or
severe stress in early life
Which one is the schizophrenic
brain?
Neurobiology and Mental Illness,
cont’d
• Decreased Cerebral Blood Flow
(Some examples:)
-In Prefrontal cortex: Schizophrenia
-In Frontal lobe: Attention-Deficit Hyperactivity
Disorder (ADHD)
Which one is the schizophrenic
brain?
Cerebral blood flow (CBF) levels
in middle cerebral artery of gray matter
Source: Romanian Journal of Psychopharmacology, 2008
Neurobiology and Mental Illness,
cont’d
• Neurotransmitter Dysfunction
Lack of availability or lack of secretion
(Some examples:)
– Too much dopamine: Schizophrenia
– Insufficient serotonin: Depression
– Insufficient norepinephrine: Depression
– Insufficient GABA: Anxiety disorders
– Too much norepinephrine: Anxiety Disorders
NB and MI, cont’d
• Neuroendocrine Dysfunction
(examples)
-Altered Hypothalamic regulatory mechanisms:
Anorexia Nervosa
-Increased Hypothalamic-Pituitary-Adrenal Axis
(HPA) activity causing elevated cortisol (stress
hormone) levels: Caused by early life
deprivation, trauma or stress
-Thyroid dysfunction: (Hyper-)Anxiety,
(Hypo-) Depression
Implications for Nursing

• MI must be seen as interaction of
biological-interpersonalenvironmental factors
• Psychiatric/mental health nurses
can not “just take care of the
mind.”
• Medical needs of mental health
clients need equal attention
Psychopharmacology
• Metabolism of Psychotropic Drugs
Involves 2 Enzyme Systems
– Cytochrome P-450 (CYP) System
• controls 75% of all drug metabolism
– Monamine oxidase (MAO)-inactivates
monoamines
• dysfunction in this system causes serious
sympathetic SEs
Psychopharmacology: Drug
Interactions and Adverse Effects
• Synergism and opposition are common
problems
• The “right” prescription: how do you know?
• Ethical and legal implications
Implications for Nursing: Client
Teaching
• Must have patient Consent in order to teach
• Client and Family Attitudes: What are the
issues?
• Side Effects: What are the issues?
• Culture and Personal Beliefs: What are your
attitudes about these drugs? How do they
compare to your client’s?