Concepts of Neurobiology

Introduction v The 1990’s was called the “decade of the Brain” with the challenge of studying the biological basis of behavior v In keeping with the “neuro scientific revolution”, greater emphasis is placed on the organic basis of mental illness v Research is ongoing and new discoveries are being made. fMRI and sMRI’s are giving us new information.

What makes a brain happy and healthy? v Balanced Neurotransmitters v Brain uses the most glucose –Healthy Diet (serotonin/GABA shake) –Aerobic exercise –Empathic conversation –8 hours of sleep –Listening to music –Being in nature –Hearing an inspiring speech –Helping others

What makes a brain happy? But is not so healthy v Coke, potato chips, and chocolate v A margarita v Going shopping v Driving fast v Cocaine v Nicotine v Rollercoasters/action movies v Gambling v Computer Games

Thee Parts of the Brain v 1. Forebrain –A. Cerebrum –B. Diencephalon v 2. Midbrain v 3. Hindbrian or brain stem

v 1. The Forebrain –A. Cerebrum u Consists of right and left hemisphere connected by a deep groove called the corpus callosum. u Each hemisphere is divided into four lobes: –Frontal lobes –Parietal lobes –Temporal lobes –Occipital lobes

The Lobes of the Cerebrum: a closer Look v Frontal lobes –The executive; decision maker, reliant on other parts of the brain for data. Prefrontal is the personality v Parietal Lobes –Perception, interpertation touch body perception v Temporal Lobes –Hearing v Occipital Lobes –Sight

Forebrain: Diencephalon v The diencephalon connects the cerebrum with the lower brain structures – Limbic System: “the bagel”or the “emotional brain:” – Limbic system consists of many structures – Contain “4 F’s”-Feeding, fighting, fleeing and fornicating – Memory, Pleasure Pathway, emotions, motivation

Forebrain: Diencephalon (Limbic System) v Connects the cerebrum with the lower brain structures v Very powerful v Do not underestimate v Pleasure Emotions Cravings Memories v Can overwhelm the Frontal Lobe

Other Important Structures in the Limbic System v Hippocampus-Contains memory v Amigdala-stores affect about memories, ie, fear, anger, rage, love, and happiness v Both structures are bilateral, under the temporal lobe v VTA is a pathway in this area of the brain that is the seat of craving in addiction

Diencephalon Cont. v Basil Ganglia-Modulates motor behavior; appropriate muscle tone and posture v Balances excitatory (acetylcholine) and inhibitory(dopamine) neurotransmitters in extra-pyramidal system. GABA inhibits also. v Hypothalmus, pituitary gland v Thalmus: integrates sensory input,except smell, which Limbic does

The Midbrain and Hindbrain v The midbrain, or mesencephalon, is responsible for visual, auditory, and balance (righting) reflexes. Substantia Nigra Produces Dopamine in this area v Hindbrain or Brain stem – Pons: regulates respiration and muscle tone – Medulla: reg. heart rate, blood pressure, – Cerebellum: muscle tone and coordination

Nerve Tissue v CNS: neurons, composed of: – Cell body, contains nucleus – Axon, transmits message to next cell – Dendrites, receives messages from cells v Three classes of neurons in CNS – Afferent, (sensory) – Efferent, (motor) – Interneurons, in CNS

Neurons: a reveiw

Synapses v The synapse is the junction between two neurons. v Synaptic Cleft: space between neurons v Pre-synaptic neuron: area of axon where neurotransmitters are stored. v Postsynaptic neuron: area of dendrite where receptor sites are located. v Electrical impulses begins the process.

Synapse: a review

Neurotransmitters v Play an important role in human emotions and behavior v Are the target for the mechanism of action for psychotropic medications v Summary: Neurotransmitters are released into the synaptic cleft from the axon to the dendrite. The substance is either inactivated or returned to the axon.

Categories of neurotransmitters v Cholinergics – Acetylcholine: involved in sleep, arousal, movement, MEMORY, v Monoamines – Norepinephrine: effects mood, cognition, perception, locomotion, CV functioning, sleep and arousal

Monoamines: v Dopamine: effects movement, coordination, emotions, voluntary judgment, and release of prolactin v Serotonin: effects sleep, arousal, libido, appetite, mood, aggression, pain perception, coordination, and judgment v Histamine: Not sure of influence on mood

Amino Acids and Neuropeptides v Amino Acid: gamma aminobutyric acid(GABA) functions as an inhibitor neurotransmitter. Has a calming effect. v Neuropeptides: endorphins and enkephlins, modulates pain and reduces peristalsis. Also called “natural opiates”

Autonomic Nervous System v Sympathetic: Dominates in stressful situations, prepares body for fight or flight v Parasympathic: Dominates when person is relaxed

Neuroendocrinology v Hypothalamus-has direct control over the pituitary gland, the “master gland” – All these effect health. Our main concerns are: TSH, ACTH, Melatonin v Circadian Rhythms- implications in many mental illness as it effects the ability to sleep.

Other factors in Neurobiology v Genetics: research has shown that all major mental illness seem to have a genetic base. v Psychoimmunology: Normal immune responses are decreased with grief, bereavement, and depression.

Implications for Nursing v Nature-Nurture dichotomy does not exist. Each effects the other. v A nurse never “Just takes care of the body” even if you want to. v Psychiatric/mental health nurses can not “Just take care of the mind.” v “Pathophysiology” check lab work daily. Listen and observe v

Goals for the Student Nurse in Psychiatric Nursing v Learn about mental illness v Improve communication v Psychotropic Medication v Decrease your fear of “Mental Patients” v Attend groups

Neurobiology The End