Chapter 2 Neuroscience and Behavior

Neural Communication Biological/neuroscience Psychology –branch of psychology concerned with the links between biology and behavior –Want a better understanding of sleep and dreams, depression and schizophrenia, hunger, sex, stress and disease

Neural Communication Neuron –a nerve cell –the basic building block of the nervous system Dendrite –the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body –Brings in info

Axon –the extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands Myelin [MY-uh-lin] Sheath –a layer of fatty cells that encase the fibers of many neurons –Speeds up neutral impulses –MS

Neural Communication Action Potential –a neural impulse; a brief electrical charge (Ion) that travels down an axon –Outside the Axon= positive ions –Inside the Axon= negative ions –Even positive and negative= resting potential, which acts like a gate. – Depolarization= unfreezes or ungates the axon allowing the message to go through –Refractory period= resting period, when extra atoms are pushed out –Some signals excite and some inhibit

Threshold –the level of stimulation required to trigger a neural impulse –All or nothing

Neural Network

Neural Communication SynapseSynapse –junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron –tiny gap at this junction is called the synaptic gap or cleft Neurotransmitters –chemical messengers that cross the synaptic gaps between neurons –Excite or inhibit –Lock and key –Reuptake

Neurotransmitters Each pathway uses different neurotransmitters, each neurotransmitter has a different function Acetylcholine ( ACH) - muscle contraction, learning and memory –Alzheimer's Endorphins- –“morphine within” –natural, opiatelike neurotransmitters – linked to pain control and to pleasure Dopamine- alertness and movement –Parkinson's –schizophrenia

Neurotransmitters Serotonin- mood, hunger,sleep and arousal depression Norepinephrine- controls alertness and arousal Gamma-aminobutryic acid (GABA)- inhibitory neurotransmitter Glutamate- A major excitatory neruo., memory –Migraines –Seizures

Dopamine pathways

How Drugs Effect Neurotransmitters Many drugs mimic the neurotransmitter –Agonists excite –Antagonists inhibit

Neurotransmitter molecule Receiving cell membrane Receptor site on receiving neuron Agonist mimics neurotransmitter Antagonist blocks neurotransmitter

The Nervous System

Central (brain and spinal cord) Nervous system Autonomic (controls self-regulated action of internal organs and glands) Skeletal (controls voluntary movements of skeletal muscles) Sympathetic (arousing) Parasympathetic (calming) Peripheral

The Nervous System –Body’s communication system –2 parts- Central and Peripheral –The Nervous System uses 3 types of neurons 1. Sensory 2. Interneurons 3. Motor neurons

Central Nervous System

Peripheral Nervous System

A. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cordA. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cord A. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cordA. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cord A. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cordA. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cord A. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cordA. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cord

The Peripheral System 2 components Somatic Nervous System –1. Somatic Nervous System- controls our skeletal muscles Autonomic Nervous System –2.Autonomic Nervous System- glands,muscles of our internal organs –Heartbeat, digestion, hormones Sympathetic Nervous System –1. Sympathetic Nervous System- defense actions ( increases heartbeat, muscles contract…..) Parasympathetic –2. Parasympathetic- it conserves energy

Central Nervous System ( CNS) Spinal Cord and Brain Spinal Cord connects peripheral system to the brain Reflexes

Skin receptors Muscle Sensory neuron (incoming information) Motor neuron (outgoing information) Brain Interneuron Spinal cord

The Brain

Tools of Discovery Manipulating the brain – Lesions electromagnetic charges chemical and magnetic stimulation Clinical Observations - looking at damaged brains Recording Electrical Activity EEG ( electroencephslogram) an amplified recording of the waves of electrical activity that sweep across the brain’s surface

EEG

Tools of Discovery Neuroimaging- –CT ( Computed tomography) Scan- X- Ray photographs –PET ( Positron emission tomography) Scan Looks at sugar glucose to determine brain activity –“HOT SPOTS” –MRI- ( Magnetic Resonance Imaging) generated images that distinguish among different types of soft tissue; allows us to see structures within the brain.

PET Scan

MRI

The Brain

Lower Level Brain Structure

Lower Brain Lower Brain- performs life saving operations freeing the higher brain regions to think, dream, memorize.. We are unaware of most of its functions

Lower Level Brain Structure The Brainstem 1.Brainstem- where spinal cord enters the skull Crossover point for nerves responsible for automatic survival functions 2.Medulla- Heartbeat and breathing

Lower Level Brain Structure The Brainstem 3. Reticular Formation- Filter and relay station Controls arousal 4. Thalamus- Sensory input station,except smell Receives higher brains replies Controls electrical cycles. Slows during sleep;speeds up while awake

Lower Level Brain Structure The Brainstem 5. The Cerebellum Coordinates voluntary movements –Balancing, walking………. Nonverbal voluntary movement 6. Pons –Regulates sleep

The Limbic System

The Limbic System –associated with emotions such as fear and aggression and drives such as those for food and sex –includes the hippocampus, amygdala, and hypothalamus.

The Limbic System 1. Hippocampus- Processes memory Forms new memories 2. Amygdala- Aggression and fear

The Limbic System 3. Hypothalamus- –Controls pituitary gland (hormones) –directs several maintenance activities eating drinking body temperature –Triggers autonomic nervous system –Pleasure Center –Reward Deficiency Syndrome- alcoholism, binge drinking, drug abuse

Psychosurgery? What is psychosurgery?

The Cerebral Cortex Thin layer covering your cerebral hemispheres- wrinkly thing Neural cells Controls body and info The bigger the better

The Cerebral Cortex Structure and Functions 1.Each hemisphere is divided up into 4 lobes Frontal Occipital Temporal Parietal 2.Glial Cells- - neural nannies Support the 22 billion nerve cells

The Cerebral Cortex 1. Frontal Lobe- speaking, muscle movement, making plans, judgments Motor Cortex- outgoing messages to the body

The Cerebral Cortex 2.Parietal Lobe- sensory cortex Sensory Cortex-registers and processes body sensations Receives info from skin receptors More sensitive= bigger area 3.Occipital Lobe- receives visual from opposite sides

The Cerebral Cortex 4.Temporal Lobes- receive auditory simulation from opposite sides Don’t need real sounds

Functional MRI scan of the visual cortex activated by light shown in the subject’s eyes`

Auditory cortex Visual cortex

The Cerebral Cortex Association Areas- zareas of the cerebral cortex that are not involved in primary motor or sensory functions zinvolved in higher mental functions such as learning, remembering, thinking, and speaking

Association Areas Aphasia –impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding) Broca’s Area –an area of the left frontal lobe that directs the muscle movements involved in speech Wernicke’s Area –an area of the left temporal lobe involved in language comprehension Angular Gyrus-auditory sounds

The Cerebral Cortex zBrain activity when hearing, seeing, and speaking words

Brain Reorganization Plasticity- neural tissue can reorganize in response to damage Orgasm in foot Most plastic when young

Our Divided Brain Corpus Callosum –largest bundle of neural fibers –connects the two brain hemispheres –carries messages between the hemispheres Corpus callosum

Split Brain a condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them “alien hand syndrome”

Hemispheric Differences Specialization Each hemisphere has its own specialties Most people are stronger in one hemisphere Left- logical, verbal, sequential Right- emotional, expressive, better at spatial relations

Handedness 90% right handed The percentage of lefties sharply declines with age Age in years 14% Percentage of left-handedness

Neural and Hormonal Systems Endocrine System –the body’s “slow” chemical communication system –a set of glands that secrete hormones into the bloodstream

Endocrine System Hormones –chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another –Growth, reproduction, metabolism, mood………

Endocrine System Adrenal Glands –a pair of endocrine glands just above the kidneys –secrete the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which help to arouse the body in times of stress –Increases heart beat, blood pressure, blood sugar….. Gives us energy

Endocrine System Pituitary Gland –under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands –Master gland

Other Hormones /Glands 1.Pineal Gland- Produces melatonin regulates circadian rhythms Seasonal Affective disorder 2. Thyroid- Maintains metabolic activities Lack of thyronixe= mental retardation in children 3. Pancreas- releases insulin and glucagon which regulates blood sugar

Other Hormones /Glands 4. Gonads- –Testis and Ovaries –Release estrogen and testosterone