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 ”

Cerebrum Right and left hemispheres connected by the corpus callosum The Forebrain

Lobes of the Cerebrum

The Lobes of the Cerebrum: a Closer Look Frontal LobeFrontal 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.Reliant on other parts of the brain for data. Prefrontal area relates to features of the personality, motivation & goal settingPrefrontal area relates to features of the personality, motivation & goal setting Motor and Premotor areas: voluntary movementMotor and Premotor areas: voluntary movement

Lobes of the Cerebrum, cont’d Parietal LobeParietal Lobe –Perception, interpretation, touch, body perception Temporal LobeTemporal Lobe –Hearing  Occipital Lobe -- Vision

Limbic System “The Emotional Brain:” “The Emotional Brain:” –Consists of many structures –Controls the “4 F’s”: Feeding, Fighting, Fleeing and Fornicating –Functions include Memory, Pleasure, Emotions, 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 Thalamus-association of sensory inputs with pleasant and unpleasant feelingsThalamus-association of sensory inputs with pleasant and unpleasant feelings Hippocampus-memory processing, and making of new memoriesHippocampus-memory processing, and making of new memories Amygdala-stores feelings relating to memories,Amygdala-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” –Contains many dopaminergic neurons that connect to sites in limbic system connect to sites in limbic system –seat of craving in addiction

Basal Ganglia or Extrapyramidal System Regulate motor behavior, appropriate muscle tone and postureBasal Ganglia or Extrapyramidal System Regulate motor behavior, appropriate muscle tone and posture –Balances excitatory and inhibitory neurotransmitters. Important Structures Connecting to the Limbic System, cont’d

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 MesencephalonMidbrain, or Mesencephalon --Responsible for visual, auditory, and balance reflexes and posture --Responsible for visual, auditory, and balance reflexes and posture --Substantia Nigra produces Dopamine in this area --Substantia Nigra produces Dopamine in this area

Pons: regulates respiration and muscle tone Medulla: reg. heart rate, blood pressure Cerebellum: 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: 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: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)Afferent (sensory) Efferent (motor)Efferent (motor) InterneuronsInterneurons

Neurons: Review, cont’d Synapse: the contact point between two neurons.Synapse: the contact point between two neurons. Synaptic Cleft: space between neuronsSynaptic Cleft: space between neurons Pre-synaptic neuron: area of axon where neurotransmitters are stored.Pre-synaptic neuron: area of axon where neurotransmitters are stored. Postsynaptic neuron: area of dendrite where receptor sites are located.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.Neurotransmitters are released into the synaptic cleft (space) from the axon to the dendrite. (--Calcium ions facilitate NT release) (--Calcium ions facilitate NT release) NTs bind with receptors on post-synaptic neuron (dendrite) and activate itNTs bind with receptors on post-synaptic neuron (dendrite) and activate it Then NT substance is either deactivated or returned to the axon (“reuptake”).Then NT substance is either deactivated or returned to the axon (“reuptake”). Nerve cells can release more than one type of neurotransmitterNerve 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 NeurotransmittersNeurotransmitters –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, memoryAcetylcholine (ACh): involved in sleep, arousal, movement, memory

Categories of Neurotransmitters, cont’d MONOAMINES Norepinephrine: affects mood, cognition, perception, locomotion, CV functioning, sleep and arousalNorepinephrine: affects mood, cognition, perception, locomotion, CV functioning, sleep and arousal Dopamine: effects movement, coordination, emotions, voluntary judgment, and release of prolactinDopamine: 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 judgmentSerotonin: 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 moodHistamine (role not well understood): involved in the immune/inflammatory response appears to be involved in mood

Categories of Neurotransmitters, cont’d Amino AcidsAmino 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”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 pituitaryHypothalamus- the “master gland,” has direct control over the pituitary Hormones: all of these affect health. Our main focus in this course = TSH, Melatonin, ACTHHormones: 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.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”)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.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-interpersonal- environmental factorsMI must be seen as interaction of biological-interpersonal- environmental factors Psychiatric/mental health nurses can not “just take care of the mind.”Psychiatric/mental health nurses can not “just take care of the mind.” Medical needs of mental health clients need equal attentionMedical 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?