AP Psych Unit 2

Structures of the Brain

• Hemisphere - the brain has two hemispheres, the left side and the right side

  • The left side controls the right side of the body, and the right side controls the left side of the body (decussation)

    • The two slides of the brain are always working together

  • Left Hemisphere - specializes in language, speech, handwriting, critical thinking, calculation, sense of time and rhythm, and basically any kind of thought requiring thought analysis 

  • Right Hemisphere - appears to specialize in more widespread processing involving perception, visualization, spatial pattern, recognition of patterns, faces, emotions, melodies, and expression of emotion

• Corpus Callosum - bundle of nerve fibers that connect the two hemispheres, messages move from one side of the brain to the other

• Lateralization - there is some evidence that each brain hemisphere has its own distinct functions

• Cerebral Cortex “Gray Matter” - outer layer of the brain, the tissue is folded on itself, the folding and wrinkling allows for more surface area cortex to fit into the skull

  • Distinctly human traits including higher thought, language, and human consciousness as well as the ability to think, reason and imagine all originate in the cerebral cortex

•  Lobes - areas of the cerebral cortex, location and primary function, each with a speciality

  • Frontal Lobe - areas of the cortex located in the front and top of the brain, associated with reasoning, motor skills, higher level, cognition, and expressive language

    • Prefrontal Cortex - the brain region has been implicated in planning complex cognitive behavior, personality expression, decision making, and moderating social behavior

    • Motor Cortex - this area of the brain receives information from various lobes of the brain 

    • Broca’s Area - located in the lower portion of the left frontal lobe, controls motor functions involved with speech production and language comprehension 

      • May be involved with muscle movements for speech

  • Temporal Lobe - areas of the cortex located just behind the temples containing the neurons responsible for the sense of hearing and meaningful speech

    • Wernicke’s Area - it is located in the temporal lobe on the left side of the brain and is responsible for the comprehension of speech

      • Broca = physical    Wernicke = understanding

  • Parietal Lobe - sections of the brain located at the top and back of each cerebral hemisphere containing the centers for processing sensory signals such as touch, pressure, temperate, and pain

    • Somatosensory Cortex - part of your brain that receives and processes sensory information from the entire body

  • Occipital Lobe -  section of the brain located at the rear and bottom of each cerebral hemisphere containing the visual centers of the brain

• Brain Stem - most primitive part of the brain, base of the brain connected to the spinal cord 

  • The brain stem controls the flow of messages between the brain and the rest of the body

  • Controls basic body functions such as breathing, swallowing, heart rate, blood pressure, consciousness, and whether one is awake or sleepy

  • Medulla Oblongata “Medulla” - located at the top of the spinal cord (transition zone) controls life sustaining functions

    • Controls many vital automatic functions such as heart rate, breathing, and blood pressure

    • Where most fibers cross, resulting in contralateral (opposite side) control

  • Pons - the larger swelling above the medulla that connects the top of the brain to the bottom, the bridge between cerebral hemispheres and both medulla and cerebellum

    • Role in several autonomic functions such as stimulating breathing and controlling sleep cycles

  • The Reticular Formation - network of nerves that carry messages between parts of the brain stem (integrating the nervous system)

    • It helps regulate the intensity of pain and controls some parts of the body

    • Helps people focus on useful sensory input 

• Cerebellum “Little Brain” - helps control posture, balance, and the coordination of voluntary movements. This allows different muscle groups in the body to act together and produce coordinated fluid movement.

  • Muscle memory takes 3x as long as regular memory to set in

  • The cerebellum contains 70% of the nerves in your central nervous system

• Thalamus - processes and transmits movement and sensory information. Considered the sensory “relay station” of the brain, passing information on the cerebral cortex

  • Receives information from all the senses (routes it to the higher brain regions that deal with seeing, hearing, tasting, and touching)

• Limbic System - network of structures located beneath the cerebral cortex

  • Coordinates:

    • Emotions such as fear and aggression

    • Basic drives such as hunger and sex

    • The formation of episodic memories

• Hypothalamus - connects with many other regions of the brain and is responsible for controlling hunger, thirst, emotions, body temperature regulation, and circadian rhythms

  • The hypothalamus also controls the pituitary gland by secreting hormones

• Hippocampus - the hippocampus plays a critical role in the formation, organization, and storage of new memories as well as connecting sensation and emotions to these memories

• Amygdala “Fear Center” - primarily involved in processing emotions and survival responses

  • Becomes active during potentially threatening situations (coordinates fight or flight response)

  • Influence aggression and fear

Tools for Examining the Brain

• Researchers are still discovering the complexities of the brain. The 1990s and 2010s have each earned the title “Decade of the Brain.”

  • Researchers have learned more about the brain in the last fifty years than have been learned in the entirety of human history before that point

• Neuroscience “Brain Researchers” - neuroscience is an interdisciplinary brain science that works closely with other disciplines

  • Researchers might look into the brain activity with different tools

• Phineas Gage - known for surviving an accident where an iron rod was driven through his head, lived for 11 years after the accident

  • The most well known patient of neuroscience, when scientists realized electric shocks are not necessary for studying the brain

• Brain Autopsy - examination of brain tissue after death is currently the only definitive way to diagnose the specific neurodegenerative disorder of an individual

  • Once a specific neurodegenerative disorder is known to be common in the family, physicians may better treat the surviving family members

• Lesioning Studies - humans with brain lesions are often the subjects of research with the goal of establishing the function of the area where their lesion occurred

  • These studies, generally performed on lab rats, measure the ability to learn new skills and then transfer that learning to other situations

• Prefrontal Lobotomy - operation that removes parts of the brain to control behavior, disconnects the prefrontal cortex rom the rest of the brain

  • Developed in the 1930s, Nobel Prize in medicine in 1949 for treatment of schizophrenia 

• Hemispherectomy - brain surgery used to treat behavioral disorders or illnesses, removal of one of the halves of the brain

  • Control seizures in people who have epilepsy

• Deep Brain Stimulation - newer, less invasive method of altering the brain to eliminate behavioral symptoms

  • Surgeon creates an opening in the skull then carefully inserts an electrode through the opening to stimulate a specific area

• Transcranial Magnetic Stimulation (TMS) - noninvasive technique that alters brain activity 

  • Involves the use of an electromagnetic wand that alters the magnetic fields that affect how the brain processes emotions and mood (treat depression)

• Brain Scanning - not used to treat disorders rather they provide information about the structure of the brain or about the activity of the brain

• X-Rays - primarily show bones and other solid structures, especially useful when a person has broken bones (skull fractures)

  • Does not show details of the soft tissue in the body, not a complete evaluation

• Electroencephalograph (EEG) - measurement of the electrical activity of the brain by recording from electrodes placed on the scalp

  • Electrical output forms waves that may indicate things such as stages of sleep, seizures, and even tumors

  • Traces represent an electrical signal from a large number of neurons

• Computer Tomography (CT or CAT Scan) - two-dimensional x-ray photographs from different angles and using to create three-dimensional representation of organ

  • Identify a muscle or bone disorder, tumor, or blood clot

  • Reveals gross features of the brain

  • Often used in emergency rooms because doctors can identify critical problems in quickly

• Magnetic Resonance Imaging (MRI Scan) - brain imaging method using radio waves and magnetic fields of the body to produce three dimensional detailed images of the brain

  • GIves much better resolution of the brain than a CT scan

• Magnetoencephalography (MEG) - imaging technique used to measure the magnetic fields produced by electrical activity in the brain by extremely sensitive devices

  • Brain sends electrical signals that generate magnetic fields (activity of neurons is the activity of the brain

• Functional MRI (fMRI) - measuring Brain Activity, detects the changes in blood oxygenation and flow that occur in response to neural activity 

• Positron Emission Tomography (PET Scan) - uses trace amounts of short lived radioactive material to map functional processes in the brain (glucose)

  • When the material undergoes radioactive decay a positron is emitted, which can be picked up by the detector 

Is it Possible to Live Functionally with Half a Brain? YES!

Is it Possible to Live Functionally with Two Different Brains in the Same Head? YES!

The Adaptable Brain

• Neuroplasticity - the ability to constantly change both the structure and function of many cells in the brain in response to experience and even trauma

  • Brain is resistant to damage

  • Functional Plasticity - the brain’s ability to move functions from a damaged area of the brain to other undamaged area

  • Structural Plasticity - the brain’s ability to change its physical structure

• Split Brain - the left and right side of the brain and not working in unison and are split

The Nervous System

• Body’s communication network that consists of all nerve cells

  • “Body’s electrical wiring”

  • Allows organisms to sense, organize, and react to information in the environment

• Central Nervous System (CNS) - coordinates the actions and interactions of the brain and spinal cord, body’s main control center

  • Largest part of the nervous system

  • The spinal cord is an information highway connecting the peripheral nervous system to the brain

• Peripheral Nervous System (PNS) - includes the sensory nerves outside the brain and spinal cord that connect the CNS to the rest of the body

• Somatic Nervous System - includes the nerves that transmit signals from your brain to the skeletal muscles to allow voluntary movement 

• Sensory Neurons “Afferent Neurons” - carry information from the nerves to the central nervous system 

  • It is these sensory neurons that allow us to take in sensory information

• Motor Neurons “Efferent Neurons” - carry information from the brain and spinal cord to muscle fibers throughout the body

• Interneurons - neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs

• Sympathetic Nervous System - emergency response system, if something alarms, enrages, or challenges you “Fight, flight, or freeze”

• Parasympathetic Nervous System - functions to calm the person “rest and digest”

  • Reduces body arousal, energy, decreases blood sugar, increases blood flow to the digestive organs, decreases heart rate

• Interneurons - neurons within the brain

• Reflex Arc - signal is sent from a sensory organ to the spinal cord, which processes the information instead of passing it on to the brain

• Autonomic Nervous System - regulates involuntary and unconscious action

Neuron: “Nerve Cell”

• Specialized cell in the nervous system that receives and sends messages to different parts of the nervous system

• Neurotransmitters - are chemical messengers that carry messages from the brain to other neurons

• Glial Cells - cells that provide physical support for the neurons to grow on and around (glue)

  • 90% of the brain is composed of glial cells

  • Surround neurons, get nutrients to the neurons, clean up remains of neuron that have died

• Dendrites “Antenna” - part of a neuron, branch-like extensions that receives electrical messages from other cells

• Receptor Sites - receive signals, receptor sites are the lock where the neurotransmitter molecule fits into

• Soma “Life Support” - the cell body of the neuron responsible to maintain the cell and keep the neuron functional (nucleus included)

• Axon “Talker” - fiber that extends from the cell body to the terminal endings, its job is to carry messages out to other cells

• Axon Terminals - tips at the end of the axon, send signal to other neurons

• Synapse “Contact Point” - meeting point between neurons, at the end of the terminal button is a gap known as a synapse 

  • Synaptic Vesicles - store various neurotransmitters that are released at the synapse

  • Synaptic Cleft or Gap - less than a millionth of an inch wide

The Endocrine System

• Oxytocin - powerful hormone that acts as a neurotransmitter in the brain, regulates social interaction and sexual reproduction

  • Levels increase when we hug or kiss someone, or do a loving action

• Epinephrine “Adrenaline” - hormone produced in high stress or exciting situations, physical boost, and heightened awareness.

  • It stimulates increased heart rate, contracts blood vessel

• Cortisol - body’s main stress hormone, works with a certain part of your brain to control your mood, motivation, and fear

  • It is important that the body’s relaxation response be activated so the body’s functions can return to normal following a stressful event

Nature and Nurture 

• Nature (Genes) - all of the genes and hereditary factors that influence who we are - from our physical appearance to our personality characteristics

• Nurture (Environment) - refers to all the environmental variables that impact who we are as a person

  • Early childhood experiences

  • How we were raised

  • Social relationships

  • Our surrounding culture 

• Biological Psychology - tends to stress the importance of genetics and biological influences 

• Heredity - the sum of all biological processes by which particular characteristics are transmitted from parents to their offspring

• Genes “Little Instructions” - segments of DNA molecules are the functional units of heredity, make up the body’s blueprint

  • We have about 24,000 genes 

  • Most of the genes are same between people

  • A small percentage of our genes are different from others 

• Epigenetics - study of heritable changes in gene expression (active versus inactive genes). Study of changes in gene expression due from non-genetic crosses

  • Methylation - process by which genes turn off due to protein interaction

• Sensitive Period - for some behaviors or physical characteristics, a particular environment is important at a particular time in life for the genetic information to be expressed 

• Monozygotic Twins “Identical” - result from a single fertilized egg that splits in two, are genetically identical

• Dizygotic Twins “Fraternal” - develop from two zygotes and share 50% of their DNA

• Heritability - the extent to which differences in the appearance of a trait across several people can be accounted for by differences in their genes 

  • Can only be applied to groups of people, not an individual

Evolutionary Psychology 

• Study of how natural selection favored behaviors that contributed to survival and the spread of our ancestors’ genes, and may currently contribute to our survival into the next generation

  • It combines the science of psychology with the study of biology 

  • It can simply explain a wide variety of human behavior

• Charles Darwin’s Theory of Natural Selection - heritable characteristics that provide a survival or reproductive advantage 

• Psychological Adaptations - development or change of a mechanism in the mind