Psych 202 (Midterm #3)
Dendrites
-branchlike extensions of the neuron that detect info/signals from other adjacent neurons -INPUT (reception phase) -signals arrive at dendrites by the thousands (these signals affect polarization and therefore tell the neuron whether or not to fire)
Neurons
-cells that receive, integrate, and transmit info in the nervous system -operate thru electrical impulses, communicate with other neurons thru chemical signals, and form neural networks -3 types (sensory, motor, and interneurons) -nerve impulse flows from dendrites, to cell body, to axon, to terminal buttons, then to synapse -chain of communication between 2 neurons referred to as presynaptic (before synapse) or postsynaptic (after synapse)
Hormones
-chemical substances released into bloodstream by ductless endocrine glands (such as pancreas, thyroid, testes, or ovaries) -travel thru bloodstream until they reach target tissues where they bind to receptor sites and influence the tissues
Monoamine Oxidase Inhibitors vs. SSRIs
-both agonists of Serotonin and both reduce symptoms of depression, but they have different mechanisms of action -SSRIs block the reuptake of Serotonin and Monoamine Oxidase Inhibitors prevent the breakdown of Serotonin (increasing the amount available in synapse)
Growth Hormone (GH)
-released by pituitary gland -prompts bone, cartilage, and muscle tissue to grow or helps them regenerate after injury -many people have self-administered to increase body weight and size
Schizophrenia
-result of too much dopamine and hyperactive dopamine receptors -antipsychotic medications=dopamine antagonists (interfere w/ DA at post-synaptic receptors) results in those affected with less delusion and more communicative when taking meds
Cerebral Cortex
-thought, planning, detailed perceptions, and complex behaviors -outer layer of brain tissue which forms the convoluted surface of the brain -2 hemispheres consisting of 4 lobes
Oligodendrocytes
-type of Glial cell -asymmetrical and branched -forms myelin around axons located in brain and spinal cord (CNS)
Schwann Cells
-type of glial cell -asymmetrical -forms myelin around peripheral nerves (PNS)
Endocrine System
-ultimately under central nervous system's control -communication system that uses hormones to influence thoughts, behaviors, and actions -works together with nervous system to regulate psychological activity -uses HORMONES to communicate whereas the nervous system uses electrochemical signals
Wernicke's Area
-understanding/making sense of language -reception, receiving, comprehension of what we hear and see with regard to language -mostly in temporal lobe, some projects into parietal -damage to Wernicke's Area results in you not understanding whats being said or read
Resting Membrane Potential
-when a neuron is not active, the inside and outside differ electrically (electrical charge inside the neuron is slightly more negative than the charge outside of the neuron) -two types of ions that contribute are sodium ions and potassium ions -a neuron at rest is polarized
"Stress" and HPA-Axis
-when too much cortisol is released due to chronic stress, it increases probability of disease, exhaustion, and even premature death -consequences: more abdominal fat, arterial fats (higher likelihood of strokes), weaker immune system, and a reduction in hippocampal neurogenesis (memory/cognition reduced as a result)
Axon Hillock
-where cell body and axon meet (very sensitive to shift in charge) -where depolarization occurs -when ionic state of membrane shifts to a certain point, axon hillock "flips" which results in sending an action potential
Drugs/Toxins Effects on Neurotransmitters
1. can alter how a NT is synthesized 2. can raise or lower the amount of an NT released from terminal buttons 3. can block reuptake (change way NT is deactivated in synaptic cleft) and affect the concentration of the neurotransmitter -can also mimic neurotransmitters and bind with their receptor as if they are the real thing (receptor cannot tell a real NT from a forgery)
Sympathetic Division of Autonomic Nervous System
-"fight or flight" -prepares body for action (pupils dilate, bronchi relax, heartbeat accelerated and strengthened, digestion inhibited, blood vessels of internal organs contract) -activated in distress, sexual arousal, anxiety, or unhappiness -chronic activation of sympathetic nervous system is associated with medical problems (heart disease, asthma, ulcers, etc.) via Hans Selye
"Neocortical Areas"
-"higher" order cognitive processes (above reptilian/alligator brain) -each area performs different functions, all work together
Repolarization
-"natural restoration" -neuron returns to its slightly negative resting state
Hippocampus
-MEMORY
Action Potential
-"neural firing" -CAUSES EXOCYTOSIS (migration of synaptic vesicles toward synaptic space; binding of synaptic vesicle with membrane of synaptic knob; release of NT in vesicles into synaptic space) -neural impulse that passes along the axon and subsequently causes the release of chemicals from the terminal buttons -when a neuron fires, sodium gates in cell membrane open (sodium ions rush into the neuron which causes the inside of the neuron to become slightly more positively charged than the outside) -fraction of a second later, potassium channels open and allow potassium ions inside the cell membrane -(this change in charge of the inside/outside of the neuron is the basis of the action potential) -as sodium gates close, sodium stops entering cell -potassium ions also stop exiting the cell
Parasympathetic Division of Autonomic Nervous System
-"rest and digest" -returns body to its resting state -pupils contract, bronchi constrict, heartbeat slows, digestion stimulates, vessels dilate
Physostygmine Injection (Joseph Martinez Experiment)
-ACh agonist (ENHANCEMENT of memory) -stimulates synapse by blocking the enzyme that usually breaks down ACh -prevents enzymatic deactivation of ACh
Amphetamines, Cocaine
-AGONIST (increase/facilitate NT effects) -especially powerful effects on dopamine (stimulates pleasure center)
L-Dopa
-AGONIST (increase/facilitate NT effects) -molecule that is necessary in synthesizing dopamine (in cell body) -first line of defense in onset of Parkinson's disease (help neurons produce more Dopamine) -more L-Dopa in system=potentially more Dopamine product made
Ecstasy
-AGONIST (increase/facilitate NT effects) -release massive amounts of Serotonin-makes people extremely happy (for time being) -terminal buttons destroyed if ecstasy is taken often which can result in depression later in life
Antipsychotic Medications
-ANTAGONIST (decreases/interferes with NT effects) -block post-synaptic Dopamine receptors (which results in impaired motor effects) -side effects: produce symptoms that mimic Parkinson's disease (Parkinsonian-like side effects) -main goal of medications: reduce dopamine levels that are interfering with thinking and judgments and that are causing hallucinations and delusions
Curare
-ANTAGONIST (decreases/interferes with NT effects) -operates in peripheral nervous system by competing with Acetycholine at junction motor nerve and muscle--temporarily paralyzes -essentially blocks Acetylcholine from fitting in with its receptor
Acetylcholine (ACh)
-NT -motor control at junctions between nerves and muscles (binds with receptors on muscles making them contract or relax) -links motor neurons and muscles (synapse at muscle) -usually allows muscle fibers to operate -excites skeletal muscle and inhibits heart muscle -Botulism (Botox) inhibits release of ACh (because of its ability to paralyze muscles) -ACh antagonists can cause temporary amnesia (Curare is ACh antagonist) -ACh agonists may enhance memory -Alzhemirs patients have low levels of ACh -also involved in learning, memory, sleeping, and dreaming (affects memory and attention) IN CNS!!!
Endorphins
-NT -pain reduction, reward
GABA (gamma-aminobutyric acid)
-NT -primary inhibitory neurotransmitter in the nervous system -more widely distributed throughout brain than any other NT -w/o inhibitory effect of GABA, synaptic excitation might get out of control and spread throughout brain chaotically -epileptic seizures may be cause by low levels of GABA -GABA agonists are widely to treat anxiety disorders -inhibition of action potentials, anxiety reduction, intoxication (through alcohol) -lowers arousal levels, reduces anxiety
Results/Conclusions of Joseph Martinez Experiment
-Scopolomine caused blocked post-synaptic ACh receptors and impaired memory (ACh antagonist) -Physostygmine caused memory enhancement by inhibiting the enzyme that catabolizes ACh
Autonomic Nervous System (ANS)
-a component of PNS that transmits sensory signals and motor signals between the CNS and the body's glands and internal organs (visceral muscles) -regulates the body's internal environment by stimulating glands and by maintaining internal organs -nerves in ANS also carry somatosensory signals from glands/internal organs to the CNS (how full you are, how anxious you feel)
Plasticity
-a property of the brain that allows it to change as a result of experience, drugs, or injury
Limbic System
-above brainstem, surrounded by cortex -critical to motivation, emotion, memory -contains: thalamus (sensory relay station), amygdala (aggression and fear-anxiety), hippocampus (memory formation), basal ganglia (movement and via NUCLEUS ACCUMBENS, reward), hypothalamus (regulates temp, some weight regulatory disorders, hunger, activity of ANS, hormone release via pituitary, site of "pleasure center")
Saltatory Conduction
-action potentials "jump" along the axon from one node of ranvier to the next -produces faster neural speed and thereby increases how quickly effects at the synapse can occur
Selective Permeability
-affects ion flow through the membrane -membrane only allows some types of ions to cross more easily than others -partially because of this, more potassium than sodium is inside the neuron (contributes to polarization)
Depolarization
-as neuron fires, it allows more positive ions into the cell
Alzheimers Disease
-associated with diminished Acetylcholine functioning (low levels of ACh)
Frontal Lobe
-association cortex -thought, planning, movement
Occipital Lobe
-back portion of head -important for vision -"visual cortex" -there exists a pathway where signals are send back to occipital lobe allowing us to see (vision ultimately an internal event)
Neurotransmitters
-chemical substances that carry signals across the synaptic cleft from one neuron to another -when an action potential travels to the terminal button, it causes the vesicles to attach to the presynaptic membrane and release neurotransmitters into the synaptic cleft -neurotransmitters then spread across the cleft and bind to SPECIFIC receptors on the postsynaptic neuron -the same neurotransmitter can send excitatory or inhibitory postsynaptic signals depending on the particular receptor's properties and its location in the brain -effects of neurotransmitter are a function of the receptor to which it binds, not the neurotransmitter itself
Cell Body (Soma)
-collects and integrates info from thousands of other neurons (INTEGRATION) -neurotransmitters are synthesized in the cell body
Interneurons
-communicate within local or short-distance circuits only with other neurons -within CNS transmission -vastly outnumber sensory and motor neurons (several millions of each compared to 100 billion interneurons)
Somatic Nervous System
-component of PNS that transmits sensory signals and motor signals between the CNS and the skin, muscles, and joints -initiate, inhibit, or modulate movement
Peripheral Nervous System (PNS)
-consists of all other nerve cells in the body not in CNS -includes somatic and autonomic nervous systems -transmits variety of info to central nervous system -responds to specific messages from CNS to perform specific behaviors
Central Nervous System (CNS)
-consists of brain and spinal cord -organizes and evaluates info received from PNS and directs PNS to perform certain behaviors/adjustments -
Synaptic Vesicles
-contain bundles of neurotransmitters -vesicle attaches to presynaptic membrane and releases neurotransmitters into synaptic cleft
Hypothalamus
-critical in integrating the nervous and endocrine systems -indispensable to organism's survival -located just above roof of mouth -receives input from and projects influence to almost everywhere in the body and brain -affects function of many internal organs, regulates body temperature, body rhythms, blood pressure, and blood glucose levels -involved in many motivated behaviors as well (thirst, hunger, aggression, and lust) -pleasure center
Glial Cells
-different than neurons -support neurons -outnumber neurons 10:1 -make up the myelin sheath -3 types of Glial cells (oligodendrocytes, schwann cells, and astrocytes)
Motor Neurons
-direct muscles to contract or relax (producing movement) -often called EFFERENT neurons (transmit signals from the brain to the muscles throughout the body) -both sensory and motor neurons work together to control movement
Antagonists
-drugs that inhibit the actions of neurotransmitters -decrease release of NTs, fewer inside each vesicle -can help destroy NTs in synapse -can mimic an NT to block real NT from binding to that receptor
Amygdala
-emotion -immediately in front of hippocampus -vital role in learning to associate things with emotional responses (unpleasant food with disgust) -enables us to overcome instinctive responses -intensifies function of memory during times of emotional arousal -responds to stimuli that elicits fear -involved in evaluating a facial expression's emotional significance -involved in processing of sexual arousal -shows increased activity when people view fearful expressions
Enzyme Deactivation
-enzyme destroys the neurotransmitter in synaptic cleft -diff enzymes break down diff neurotransmitters -metabolic breakdown process (catabolism) -NT's broken down into parts, metabolize, and then are eliminated through blood and urine -a type of enzyme is monoamine oxidase
Monoamines
-epinephrine, norepinephrine, dopamine, and serotonin -grouped together because of their same molecular structure -major functions are to regulate arousal, regulate feelings, and motivate behavior
Joseph Martinez Experiment
-explores causal relationships between CNS Acetylcholine Processes and Learning and Memory Processes ("consolidation" of learning) -took drug and manipulated them in experiments with mice (Scopolomine and saline injections) -used simple learning situation (maze with 2 arms and food in one arm) -mouse learns quickly to run down the arm with food -because it takes a long time for a memory to become permanent, it allowed for interference of the process by injecting the mice with said drugs (mice were initially trained in a drug-free situation) -Operational IV: Scopolomine (ACh antagonist) vs. Saline injection -Operation DV (what they measured): "time" it took to find food -Theoretical DV (what was inferred): "memory"
Brainstem
-extension of spinal cord, "inner core" of brain, regulates life support -consists of medulla oblongata (vital functions), pons (reticular formation), and midbrain -contains network of neurons known as "reticular formation" which projects up into the cerebral cortex and affects general alertness/sleep/attention/wakefulness (serotonin neurons involved in reticular formation) -houses structures that control functions associated with survival (such as breathing, swallowing, vomiting, urination, and orgasm)
Myelin Sheath
-fatty material made up of glial cells -insulates axon (like plastic tubing around wires) and allows for rapid movement of electrical impulses along the axon
Ion Channel
-flow of ions thru channel is controlled by gating mechanism -located at Nodes of Ranvier -when a gate is open, ions flow in and out of the cell membrane -a closed gate prevents this passage ^
Prefrontal Cortex
-frontmost portion of frontal lobes, esp. prominent in humans -important for attention, working memory, decision making, appropriate social behavior, and personality
Synaptic Cleft
-gap between axon of a "sending" neuron and dendrites of a "receiving neuron that contains extracellular fluid (neurons do not touch each other, they communicate by sending signals into the synaptic cleft) -chemicals leave one neuron, cross the synapse, and pass signals along to other neurons' dendrites
Thalamus
-gateway to cortex -receives almost all incoming sensory info before that info reaches the cortex
Pituitary Gland
-gland located at base of hypothalamus that sends hormonal signals to other endocrine glands, controlling their release of hormones. -"master gland" of the body
Temporal Lobe
-hearing/memory/object and face perception -most of Wernicke's Area is here
Nucleus Accumbens
-important for experiencing reward and motivating behavior -nearly every pleasurable experience activates dopamine neurons in the nucleus accumbens -the more desirable objects are, the more they activate basic reward circuitry in our brains
Parietal Lobe
-in front of occipital lobes and behind frontal lobes -touch, spatial relations/layout of an environment -somatosensory cortex located here -some of Wernicke's Area extends here
Agonists
-increase/facilitate/enhance the actions of neurotransmitters -can increase how much NT is made, so there is more inside each vesicle -can block reuptake of NTs -can mimic a particular NT and bind to its receptors
Terminal Buttons
-knoblike structures at the end of an axon -release chemical signals from the neuron into the synapse because of action potentials
Cerebellum
-large protuberance connected to back of brain stem -looks like extra little brain -important for proper motor function -COORDINATED MOVEMENT AND BALANCE -damage to different parts produces very different effects
Substantial Nigra
-located within basal ganglia -particularly associated with the death of dopamine-containing neurons -mostly associated with motor control
Axon
-long, narrow, outgrowth of a neuron by which info/electrical impulses are transmitted to other neurons (TRANSMISSION) -vary tremendously in length -OUTPUT
Gonads
-main endocrine glands influencing sexual behavior -males=testes, females=ovaries -Androgens more prevalent in males and estrogens are more prevalent in females -gonadal hormones influence development of secondary sex characteristics and adult sexual behavior
Phineas Gage
-man damaged skull -rod drove thru prefrontal cortex - recovered well but his personality changed -became more fitful, irreverent, profane, impatient, not as receptive to social norms
Corpus Callosum
-massive bridge of millions of axons connecting the two hemispheres of the cerebral cortex -allows info to flow between them
Sodium-Potassium Pump
-mechanism in the membrane that also contributes to polarization -works to increase potassium and decrease sodium inside the neuron
Dopamine (DA)
-monoamine NT -DA tracts "project" widely throughout the brain (limbic system and cortical structures) dealing with emotion/motivation and thinking/planning/judgment/language -reward and motivation (eating when hungry, drinking when thirsty, and having sex when aroused activate dopamine receptors and are therefore perceived as pleasurable) -also involved in motor control over voluntary movement and planning (muscular activity) **critical in control of movement -lack of dopamine: problems with movement
Serotonin (5-HT)
-monoamine NT -especially important for emotional states, impulse control, and dreaming -involved in sleep-wakefulness rhythms -massively depleted by Ecstacy (terminal buttons often destroyed) -low levels associated with sad and anxious moods, food cravings, and aggressive behavior -drugs that block serotonin reuptake are used to treat depression, OCD, eating disorders, and obesity. -SSRIs specifically target serotonin (ex: Prozac) and are prescribed widely to treat depression (AGONISTS)
Norepinephrine (NE)
-monoamine NT -increases arousal, vigilance, and alertness (heightened sensitivity to surroundings) -increased levels may be involved in mania -decreased levels may be involved in depression -tricyclic antidepressant medications inhibit reuptake, thus functioning as norepinephrine agonists
Epinephrine
-monoamine NT -initially called adrenaline -responsible for burst of ENERGY after an event that is exciting or threatening -"fight or flight"
HPA-Axis
-neural hormonal loop/complex chain of events triggered by stressful events -hypothalamus-->pituitary gland-->adrenal glands -hypothalamus sends chemical message to pituitary gland and the pituitary gland secretes the hormone ACTH. ACTH then travels through the bloodstream and reaches the adrenal glands. The adrenal glands then secrete cortisol. ---cortisol increases the amount of glucose in the bloodstream. Adrenal glands also release norepinephrine and epinephrine which activate the sympathetic nervous system. -help body prepare to respond to a stressor
All-or-None Principle
-neuron normally barraged by thousands of excitatory and inhibitory signals, firing determined by frequency of those signals (any one signal doesn't have much influence on the neuron firing) -if sum of excitatory and inhibitory signals leads to a positive change in voltage that exceeds threshold, an action potential is generated -a neuron either fires or it doesn't, it cannot partially fire -neuron fires with same potency each time (can't be described as weak or strong) -how often neuron fires depends on strength of stimulation
Neurons vs. Nerves vs. Tracts
-neurons: cell that transmits info in nervous system -nerve: group of axons of neurons that come together in a cable of fibers (PNS) -tract: same as nerve but refers to CNS!!!
Sensory Neurons
-often called AFFERENT neurons (carry info from sensory receptors to brain) -transmit somatosensory info from peripheral sensory organs to CNS usually via the spinal cord -affect the brain/emotional processes
Basal Ganglia
-part of limbic system -system of subcortical structures crucial for planning and MOVEMENT -receive input from entire cerebral cortex and project that input to brain stem and back to the motor planning area of cerebral cortex via the thalamus -damage can produce symptoms from parkinsons to huntingtons disease -damage can also impair the learning of moments and habits (such as automatically looking for cars before you cross the street) -large tracts of dopamine containing neurons link up with motor processes here
Potassium Ions
-pass through the membrane through potassium channels -more of potassium ions inside the neuron than sodium -negatively charged ion
Sodium Ions
-pass through the membrane through sodium channels -positively charged ion
Reuptake
-process whereby a neurotransmitter is taken back into the presynaptic terminal buttons, thereby stopping its activity -action potential prompts terminal buttons to release neurotransmitter into the synaptic cleft and then take it back for recycling -cycle of reuptake and release repeats continuously
Broca's Area
-production of language -ability to speak/articulate coherently -located in frontal lobe (left frontal region)
Parkinson's Disease
-results from dopamine depletion (dopamine producing neurons slowly die off) -tracts of DA neurons degenerate in Basal Ganglia -characterized by muscular rigidity, tremors, and difficulty initiating voluntary action -in later stages, people suffer from cognitive and mood disturbances -affects about 1 in every 200 older adults (usually don't experience symptoms until after age 50) -antipsychotic medications are DA antagonists, interfering with DA at post-synaptic receptors -treatment=L-DOPA
Excitatory Signals
-signals arriving at dendrites that depolarize the cell membrane (reduce polarization) -increase likelihood that neuron will fire -if total about of excitatory input surpasses the neuron's threshold, an action potential is generated
Inhibitory Signals
-signals arriving at dendrites that hyper polarize the cell (increasing polarization) -decrease likelihood that neuron will fire
Synapse
-site where chemical communication occurs between neurons
Nodes of Ranvier
-small gaps of exposed axon, between the segments of myelin sheath, where action potentials are transmitted -ion channels ("pores") located at these gaps which allow negatively and positively charged molecules (called ions) to pass in and out of the cell when the neuron transmits signals down the axon -each ion channel matches a specific type of ion -3 part process (resting membrane potential-polarization, action potential-depolarization, repolarization-natural resting state) occurs at every node of ranvier along an axon
Receptors
-specialized protein molecules in neurons on the postsynaptic membrane (each receptor can only be influenced by one type of neurotransmitter) -neurotransmitters bind to these after passing through the synaptic cleft -receptor always has a specific response (either excitatory or inhibitory) -once neurotransmitter is released into cleft, it fills the receptor and blocks new signals until its influence is terminated -3 things terminate the neurotransmitters influence (reuptake, enzyme deactivation, and auto reception)
Astrocytes
-star shaped glial cell -supportive structural function and provides nutrients/oxygen for neurons (OF CNS)
Polarization
-state of neuron when it has more negative ions inside it than outside it -polarized state of resting neuron creates electrical energy necessary to power the firing of the neuron
Growth Hormone Releasing Factor (GRF)
-stimulates release of GH which relies on protein to build bones and muscles -also selectively stimulates the eating of protein but not of fats or carbohydrates -area of hypothalamus connected to GRF neurons is involved in sleep/wake cycles -bursts of GH, the need for protein, and the consumption of protein are controlled by the body's internal clock
Multiple Sclerosis
-symptoms can begin in young adulthood (numbness in the limbs and blurry vision) -motor actions become jerky, people lose ability to coordinate motor movements -movement, sensation, and coordination are impaired severely over time -characterized by deterioration of myelin sheath -because of demyelination, neural impulses are slowed down (axons essentially short-circuit and normal neural communication is interrupted) -as deterioration continues, axons are exposed and may start to break down -life expectancy is 5-10 years less than those who are not afflicted
Propagation
-the movement of a cell's depolarization along the axon like a wave -sodium ions rush through their ion channels, causing adjacent sodium channels to open (like toppling dominos, gates successively open) -action potential moves away from cell body to terminal buttons
Antidepressants (3 types)
AGONIST (increase/facilitate NT effects) 1. Tricycling inhibits NT reuptake, old school method that was used before SSRIs-still used if SSRIs don't work 2. Selective Serotonin Reuptake Inhibitor: inhibit 5-HT reuptake, prevent serotonin from being reuptook, resulting in more in the synapse (safer and have less side effects than Tricyclic drugs) 3. Mono-Amine Oxidase Inhibitors: (MAO-Is) slow enzymatic deactivation which prevents catabolism and results in more monoamine neurotransmitters (serotonin, norepinephrine, epinephrine, dopamine)
Scopolomine vs. Saline Injections (Joseph Martinez Experiment)
Scopolomine: -injected after mice learned the maze -as a result, animals don't remember the maze (experimental amnesia) -Scopolomine blocks receptor for neurotransmitter and essentially deactivates the synapse (ACh antagonist=IMPAIRED MEMORY) -lack of consolidation (didn't become a part of long-term memory) Saline: - necessary control group of mice -given to traumatize the mice equally with an injection to make sure they have similar experience/levels of stress
