NEUROBIOLOGICAL BASES OF BEHAVIOR MODULE 1 RNSG 2213.

NEUROBIOLOGICAL BASES OF BEHAVIOR

MODULE 1RNSG 2213

PART IAnatomy and

Physiology Review

A & P Review

Three Main Parts of the BrainThree Main Parts of the Brain1. Forebrain:1. Forebrain:

a. Cerebruma. Cerebrum

b. Diencephalonb. Diencephalon

22. . MidbrainMidbrain

3.3. Hindbrain or Brain StemHindbrain or Brain Stem

Cerebral cortex “Gray matter”

CerebrumRight and left hemispheres connected by the corpus callosum

The Forebrain

Lobes of the Cerebrum

The Lobes of the Cerebrum: The Lobes of the Cerebrum:

a Closer Looka Closer Look

• Frontal LobeFrontal Lobe– ““The Executive” or decision maker; The Executive” or decision maker;

regulation of behavior, e.g. planning, regulation of behavior, e.g. planning, adaptation to change, etc.adaptation to change, etc.• Reliant on other parts of the brain Reliant on other parts of the brain

for data. for data. • PrefrontalPrefrontal areaarea relates to features relates to features

of the personality, motivation & goal of the personality, motivation & goal settingsetting

• MotorMotor and Premotor areas: and Premotor areas: voluntary movementvoluntary movement

Lobes of the Cerebrum, cont’d

• Parietal LobeParietal Lobe– Perception, interpretation, touch, body Perception, interpretation, touch, body

perceptionperception

• Temporal LobeTemporal Lobe – HearingHearing

Occipital Lobe --Vision

Limbic System

• ““The Emotional Brain:”The Emotional Brain:”

– Consists of many structuresConsists of many structures– Controls the “4 F’s”: Feeding, Fighting, Controls the “4 F’s”: Feeding, Fighting,

Fleeing and FornicatingFleeing and Fornicating– Functions include Memory, Pleasure, Functions include Memory, Pleasure,

Emotions, MotivationEmotions, Motivation

The Forebrain: Cerebrum, cont’d

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

• ThalamusThalamus-association of sensory inputs with -association of sensory inputs with pleasant and unpleasant feelingspleasant and unpleasant feelings

• HippocampusHippocampus-memory processing, and making -memory processing, and making of new memoriesof new memories

• AmygdalaAmygdala-stores feelings relating to memories, -stores feelings relating to memories,

Structures Connecting to Limbic System cont’d

• VTA (Ventral Tegmental Area) -midbrainVTA (Ventral Tegmental Area) -midbrain– ““Pleasure pathway” or “Reward Center”Pleasure pathway” or “Reward Center”– Contains many dopaminergic neurons that Contains many dopaminergic neurons that connect to sites in limbic systemconnect to sites in limbic system– seat of craving in addictionseat of craving in addiction

• Basal Ganglia or Extrapyramidal System Basal Ganglia or Extrapyramidal System Regulate motor behavior, appropriate Regulate motor behavior, appropriate muscle tone and posturemuscle tone and posture– Balances excitatory and inhibitory Balances excitatory and inhibitory

neurotransmitters. neurotransmitters.

Important Structures Connecting to theLimbic System, cont’d

The Forebrain, cont’d

DiencephalonDiencephalon– Connects the cerebrum with the lower brain Connects the cerebrum with the lower brain

structuresstructures– Relays sensory info. to cerebral cortex Relays sensory info. to cerebral cortex

((thalamusthalamus) ) – Releases and inhibits hormones Releases and inhibits hormones

((hypothalamushypothalamus))– Regulates fluid, temperature, GI, CV function Regulates fluid, temperature, GI, CV function

(hypothalamus)(hypothalamus)

The Midbrain

• Midbrain, or Midbrain, or MesencephalonMesencephalon

--Responsible for --Responsible for visual, auditory, and visual, auditory, and balance reflexes and balance reflexes and postureposture

----Substantia NigraSubstantia Nigra produces produces Dopamine Dopamine in this area in this area

PonsPons: regulates respiration and muscle : regulates respiration and muscle tonetoneMedullaMedulla: reg. heart rate, blood pressure: reg. heart rate, blood pressureCerebellumCerebellum: muscle tone and coordination: muscle tone and coordination

The Hindbrain & Brain Stem

• Hindbrain/Brain Stem Structures

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 SystemAutonomic Nervous System– Sympathetic:Sympathetic: Dominates in stressful Dominates in stressful

situations, prepares body for fight or flightsituations, prepares body for fight or flight– ParasympathicParasympathic: Dominates when person is : Dominates when person is

relaxedrelaxed

Neurons: A Review

Nerve TissueNerve Tissue

• CNS: neurons, composed of: CNS: neurons, composed of: – Cell bodyCell body contains nucleus (genetic material) contains nucleus (genetic material)– AxonAxon transmits message to next cell transmits message to next cell– Dendrites receive messages from cell

Neurons: Review, cont’d

Three classes of neurons in CNSThree classes of neurons in CNS

• AfferentAfferent (sensory) (sensory)

• EfferentEfferent (motor) (motor)

• InterneuronsInterneurons

Neurons: Review, cont’d

• Synapse: Synapse: the contact point between two the contact point between two neurons.neurons.

• Synaptic CleftSynaptic Cleft: space between neurons: space between neurons

• Pre-synaptic neuronPre-synaptic neuron: area of axon where : area of axon where neurotransmitters are stored.neurotransmitters are stored.

• Postsynaptic neuronPostsynaptic neuron: area of dendrite : area of dendrite where receptor sites are located.where receptor sites are located.

Neurotransmission =

Chemical Signalling

Neurotransmission (Physiology)

• Neurotransmitters are released into the Neurotransmitters are released into the synaptic cleft (space) from the axon to the synaptic cleft (space) from the axon to the dendrite. dendrite.

(--Calcium ions facilitate NT release)(--Calcium ions facilitate NT release)• NTs bind with receptors on post-synaptic NTs bind with receptors on post-synaptic

neuron (dendrite) and activate itneuron (dendrite) and activate it• Then NT substance is either deactivated or Then NT substance is either deactivated or

returned to the axon (“returned to the axon (“reuptakereuptake”).”).• Nerve cells can release more than one type of Nerve cells can release more than one type of

neurotransmitterneurotransmitter

Pre-synaptic and postsynaptic neuron interchange

Neurotransmission Across the Synapse

Role of Neurotransmitters

in Mental Health

• NeurotransmittersNeurotransmitters– Play an important role in human emotions and Play an important role in human emotions and

behavior behavior – Influence motor activity and hormone levelsInfluence motor activity and hormone levels– Are the target for the mechanism of action for Are the target for the mechanism of action for

psychotropic medicationspsychotropic medications

Categories of Categories of NeurotransmittersNeurotransmitters

CholinergicsCholinergics• Acetylcholine (ACh):Acetylcholine (ACh): involved in involved in

sleep, arousal, movement, sleep, arousal, movement, memorymemory

Categories of Neurotransmitters, cont’d

MONOAMINESMONOAMINES• NorepinephrineNorepinephrine: affects mood, cognition, : affects mood, cognition,

perception, locomotion, CV functioning, sleep perception, locomotion, CV functioning, sleep and arousaland arousal

• DopamineDopamine: effects movement, coordination, : effects movement, coordination, emotions, voluntary judgment, and release of emotions, voluntary judgment, and release of prolactinprolactin

Monoamines, cont’d

• SerotoninSerotonin: effects sleep, arousal, libido, : effects sleep, arousal, libido, appetite, mood, aggression, pain perception, appetite, mood, aggression, pain perception, coordination, and judgmentcoordination, and judgment

• HistamineHistamine (role not well understood): (role not well understood): involved in the immune/inflammatory response involved in the immune/inflammatory response appears to be involved in moodappears to be involved in mood

Categories of Neurotransmitters, cont’d

• Amino AcidsAmino Acids– Gamma Aminobutyric Acid (GABA)Gamma Aminobutyric Acid (GABA)

functions as an inhibitory neurotransmitter functions as an inhibitory neurotransmitter (“(“brain calmerbrain calmer”) ”)

– GlutamateGlutamate excitatory excitatory

Categories of NTs, cont’d

• NeuropeptidesNeuropeptides: : endorphins and endorphins and enkephlinsenkephlins, modulate pain and reduce , modulate pain and reduce peristalsis. Also called peristalsis. Also called “natural or “natural or endogenous opiates”endogenous opiates”

NeuroendocrinologyNeuroendocrinology

• HypothalamusHypothalamus- the “master gland,” has direct - the “master gland,” has direct control over the pituitarycontrol over the pituitary

• HormonesHormones: all of these affect health. Our main : all of these affect health. Our main focus in this course = TSH, Melatonin, ACTHfocus in this course = TSH, Melatonin, ACTH

• Circadian Rhythms-Circadian Rhythms- implications in many implications in many mental illnesses: affect sleep cycles and mental illnesses: affect sleep cycles and regulate hormones which influence mood and regulate hormones which influence mood and emotions. emotions.

Other Factors in Other Factors in NeurobiologyNeurobiology

• GeneticsGenetics: research has shown that all : research has shown that all major mental illness seem to have genetic major mental illness seem to have genetic markers. (Increases “risk for”)markers. (Increases “risk for”)

• PsychoimmunologyPsychoimmunology: Normal immune : Normal immune responses are decreased with acute and responses are decreased with acute and chronic stress, grief, bereavement, and chronic stress, grief, bereavement, and depression.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 NursingImplications for Nursing

• MI must be seen as interaction of MI must be seen as interaction of biological-interpersonal- biological-interpersonal- environmental factorsenvironmental factors

• Psychiatric/mental health nurses Psychiatric/mental health nurses can not “just take care of the can not “just take care of the mind.”mind.”

• Medical needs of mental health Medical needs of mental health clients need equal attentionclients 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?