PSYC Chapter 2

neuron: responsible for information transmission throughout the nervous system; receive, send and integrate information in brian and rest of nervous system

glial cells: constitute the support system for the neurons.; ex = take away waste products of neurons and keep neurons chemical environment stable; typically a 1:1 ration of glial cells to neurons, but this varies in different areas of the brain.

parts of a neuron: dendrites, cell body, axon

• dendrites: fibers that project out of the cell body like tree branches; function is to receive information from other neurons, and to pass information to the cell body

• cell body: contains nucleus of the cell and other biological machinery to keep the cell alive; decides whether to pass information from dendrites to other neurons by way of axon

• axon: long singular fiber leaving the cell body; conduct information from cell body to axon terminals to trigger transmission of information

neuron communication is partly electrical and partly chemical; inside the neuron it is electrical, with an actual electrical impulse; neuron to neuron communication is chemical

• electrically, a stimuli triggers an impulse that is sent down the axon at a constant speed, no matter the strength of the stimuli

• myelin sheath: an insulating layer of a white fatty substance; impulse leaps from gap to gap instead of slowly and continuously; damage to the myelin sheath results in problems like M.S.; responsible for white matter versus grey matter in the brain

• chemically: impulse hits and causes a neurotransmitter to come out into the synaptic gap = microscopic gap between neurons; neurotransmitters enter receptor sites of dendrites of other neurons

positron emission tomography (PET) scans: harmless dose of radioactive sugar sent into the bloodstream and moves to more active areas of the brain, its metabolized and emits positrons that are detected by the computer

functional magnetic resonance imaging (fMRI): detects areas with increased blood flow and highlights them through a computer

agonist: drug or poison that increases the activity of neurotransmitters versus antagonist: drug or poison that decreases the activity of neurotransmitters.

acetylcholine (ACh): a neurotransmitter involved in learning, memory, and muscle movement; Alzheimer’s patients tend to have lower ACh; some poisons paralyze us by preventing ACh from fulfilling its function

dopamine: a neurotransmitter that impacts our arousal and mood states, thought processes, and physical movement; low levels can lead to Parkinson’s disease; l-dopa, can pass through blood-brain barrier, but not 100% effective; amphetamines and cocaine are related to dopamine as agonists

• blood-brain barrier: a protective mechanism by which blood capillaries create a barrier to prevent dangerous substances from entering the brain.

serotonin and norepinephrine:neurotransmitters that play a role in mood disorders like depression; pills prescribed are selective serotonin reuptake inhibitors that work by blocking the reuptake of serotonin

GABA and glutamate:

• GABA: is the main inhibitory neurotransmitter in the nervous system, so it keeps the brain from becoming to aroused; lack of GABA can lead to epilepsy; anti-anxiety drugs/tranquilizers are agonists for GABA

• glutamate: the main excitatory neurotransmitter in the nervous system; involved with memory storage and pain perception; excessive glutamate activity can cause death of neurons, ex = stroke

endorphins: neurotransmitters that are involved in pain relief and feelings of pleasure; nervous system’s natural pain killers; ex: runner’s high; morphine and heroin have agnostic effects on endorphins and increase the activity; biologically explain placebo effects on pain

2 major parts of the nervous system: central nervous system: made up of the brian and the spinal cord ; peripheral nervous system: remainder of the nervous system throughout the body, linking the CNS with the body’s sensory receptors, muscles, and glands

• 3 types of neurons in the nervous system: interneurons = integrate information within CNS by communicating with one another ONLY IN CNS; sensory neurons = carry information to CNS from sensory receptors, muscles, and glands; motor neurons = carry movement commands from CNS to rest of the body

• spinal cord: spans from stem of the brain down through the neck and center of the spinal column; two functions = conduit for incoming sensory data and outgoing movement commands to muscles in the body; and spinal reflexes: simple automatic action not requiring involvement of the brian

• somatic/skeletal nervous system: carries sensory input from the receptors to the CNS and relays commands from the CNS to the skeletal muscles to control their movement

• autonomic nervous system: regulates the functioning of our internal environment; involuntary

  • sympathetic nervous system: in control when we are aroused like in an emergency; expands energy

  • parasympathetic nervous system: takes over when the aroused state ends in order to return the body to its normal resting state; conserves energy

endocrine glandular system: the body’s other major communication system; not a part of the nervous system; it secretes hormones within the body into the bloodstream; connected to a part of the brain called the hypothalamus which controls the pituitary gland = releases hormones responsible for human growth and hormones to trigger release of other hormones.

emotion: a complex psychological state that involves three components: a physical component (triggered by autonomic nervous system), a behavioral component (somatic nervous system), and a cognitive component

• james-lange theory: physiological arousal and backing away are responses to the stimulus of seeing the bear; you are afraid because you are sweating and backing away

• cannon-bard theory: arousal patterns for different emotions are too physiologically alike to b used to determine which emotion is being experienced; motor nervous system produces behavioral response of backing away from the bear, and the brain produces the emotional feeling of fear

• schachter-singer two-factor theory: two important ingredients in determining the emotion: physiological arousal to tell how intense the emotion is and cognitive appraisal of entire situation allows us to label the emotion, leading to the emotional feeling

central core: brain stem spans from spinal cord to the thalamus

• medulla: links spinal cord to the brain; involved in regulating essential body functions such as heartbeat, breathing, blood pressure, digestion, and swallowing

• pons: serves as a passageway for neural signals to and from higher areas in the brain; functions as a bridge between the cerebellum and the rest of the brain and is involved in deep sleep and dreaming

• reticular formation: a network of neurons running up the center of the brain stem and into the thalamus, involved in controlling our different levels of arousal and consciousness

• cerebellum: coordination of our movements, sense of balance, and motor learning; looks like 2 mini spheres attached to the rear of the brain stem; more neurons than the rest of the brain combined; affected by alcohol

• thalamus: located at the top of the brain stem; serves as a relay station for incoming sensory information and sends each type of information to the appropriate location in the cerebral cortex

• basal ganglia: outer sides of the thalamus and concerned with the initiation and execution of physical movements; affected by alcohol

the limbic system: made up of the hypothalamus, amygdala, and hippocampus; important role in survival, memory, and emotions

• hypothalamus: a tiny structure that controls the pituitary gland and the autonomic nervous system to maintain the body’s internal environment and basic drives such as eating and drinking

• hippocampus: formation of memories, can generate new neurons

• amygdala: major role in regulating emotional experiences fear, anger, and aggression, and generating quick emotional responses directly

cerebral cortex: the control and information processing center for the nervous system; perception, language, memory, decision making, and other high order processing; largest part of the brain

• four lobes of the brain:

  • frontal: the area in front of the central fissure and above the lateral fissure

  • parietal: are behind the central fissure and above the lateral fissure

  • temporal lobe: beneath the lateral fissure

  • occipital lobe: in the lower back of each hemisphere

• motor cortex: the frontal lobe strip of cortex directly in front of the central fissure in each hemisphere; allows us to move different parts of our body

• somatosensory cortex: the parietal lobe strip of cortex directly behind the central fissure in each hemisphere where our body sensations of pressure, temperature, limb position, and pain are processed.

• visual and auditory cortex:

  • visual: primarily located in the occipital lobes at the backs of the hemispheres

  • auditory: temporal lobes

  • after passed through visual and auditory complex, it goes to the association cortex

  • association cortex: all the areas of the cerebral cortex except for those devoted to primary sensory or motor processing

broca’s area: which is responsible for fluent speech production

wernicke’s area: responsible for the comprehension of speech and reading

specializations of the left and right hemispheres:

• field of vision has 2 halves: left visual field and right visual field

consciousness: a persons subjective awareness of his inner thinking and feeling as well as his immediate surroundings; thus it is both internal and external

5 stages of sleep: 1= 5mins, 2=20 mins, 3=transitional then 4= deep sleep, then go back to stages 2 and 3 then into REM