PSYCH 320 Exam #1 Review

John Watson (1878-1958)

-Founded behaviorism; restricts study to observable behaviors -Studied maze learning in rats; argued that rats learned automatic motor habits (ability to navigate a maze), independent of external sensory cues (olfactory, auditory, tactile, visual) -Strongly supported empiricism; emphasized experience (nurture) in determining behavior and capabilities -By 1920s, behaviorism dominated the psychology of learning

Functional magnetic resonance imaging (fMRI)

A form of functional neuroimaging -Measures oxygenation level in the blood -Better spatial resolution than PET (1-2mm vs. 5 mm) -Better temporal resolution than PET -Limitations in its signal, not all brain parts are visible

Positron emission tomography (PET)

A form of functional neuroimaging -When a region is active, more oxygen is required = increased blood flow (within 4-6s) or increased glucose utilization -Injection of radioactive compound: PET measures gamma rays from the release of positrons accompanying degradation of radioactive compound

Computerized Tomography (CT)

A form of structural imaging -Takes many X-rays from different angles -High resolution for differentiating structures of different density in the brain (bone, soft tissue, fluids) -Cannot differentiate between types of soft tissues (e.g., gray vs. white matter)

Diffusion tensor imaging (DTI)

A form of structural neuroimaging -Measures diffusion water in tissue -Imaging of white matter -Index of fiber integrity

Magnetic Resonance Imaging (MRI)

A form of structural neuroimaging -Uses changes in magnetic fluid to generate image; magnet aligns atoms in brain or body -Much greater anatomical details than CT -Differentiates gray/white matter

Learning is best described as A. Changes in the mechanisms of behavior B. When you do something well C. Knowledge D. Skill acquisition

A. Changes in the mechanisms of behavior

If you think you can train any baby to be a neurosurgeon, an astronaut, or any other type of specialist, you share the ideas of: A.John Watson B. Charles Darwin C. Francis Galton D. Rene Descartes

A. John Watson

Long-term potentiation can be thought of as: A. Neurons that fire together wire together B. Neurons that fire prior to another neuron predict behavior C. Neurons that share the same neurotransmitter form the basis of learning D. Neurons that work antagonistically enhance learning

A. Neurons that fire together wire together

Gordon Bower is famous for... A. The idea of insight B. Connectionist models C. The stimulus sample theory D. Symbol-manipulation models

A. The idea of insight

Behaviorism focuses on the study of: A. observable behaviors B. brain processes C. internal thoughts D. intentions

A. observable behaviors

Synaptic plasticity

Ability of synapses to change as a result of experience Santiago Ramon y Cajal (1852-1934): speculated that connections between neurons change during learning. Used a new staining technique (Golgi) to study neurons in details, find synapses Donald Hebb (1940s): "neurons that fire together, wire together", if 2 neurons fire at, ~the same time, strengthening the synapse. Probability of neuron B firing when A becomes active increases

George Miller (1920-)

Adapted information theory to psychology -Measures how much information is contained in a message, based not only on message but also listener's prior information Measures human short-term memory capacity -Human short-term memory capacity is limited -Magic #7 -Applies to other stimuli (words, pictures...)

Sensitization in Aplysia

After tail shock (T), weak touches on siphon/mantle will elicit stronger than normal responses Tail's modulatory interneuron -Carries a message between 2 neurons, alters strength of transmission -Releases a neuromodulator (e.g., serotonin); increases the number of glutamate vesicles available from S each time it fires Heterosynaptic: involves changes across several synapses (including those not activated by the sensitizing event); increases response to any future stimulus (e.g., mantle U as well as siphon S) Degree of sensitization depends on strength of stimulus

Edward Thorndike (1874-1949)

American psychologist, student of William James -Cats and puzzle boxes -Instrumental (operant conditioning): probability of an animal making a behavioral response increases or decreases depending on the consequences that follow (law of effect)

William James (1842-1910)

American scientist, instructor at Harvard Authored Principles of Psychology (1890) Subscribed to associationism: memory of an event has many components. Remembering involves connecting these underlying components. Activation of one component can activate another etc. He believed these associations are reflected by physical connections in the brain.

Learning

An enduring change in the mechanisms of behavior involving specific stimuli and/or responses that results from prior experience with those of similar stimuli and responses -Enduring change (vs. fatigue or sensory adaptation) -Mechanisms of behavior (learning can occur without overt change in behavior) -Prior experience: (vs. maturation)

"Practice makes perfect" was first scientifically demonstrated by: A. Galton B. Ebbinghaus C. Pavlov D. Darwin

B. Ebbinghaus

The person who developed the form of learning known as classical conditioning is: A. Francis Galton B. Ivan Pavlov C. John Locke D. John B. Watson

B. Ivan Pavlov

Who was the founder of behaviorism? A. Edward Thorndike B. John B. Watson C. Hermann Ebbinghaus D. Ivan Pavlov

B. John B. Watson

What was Ebbinghaus's main contribution to psychology? A. The use of nonsense syllables B. The experimental study of learning and memory C. Double blind experimental procedures D. The use of correlational research

B. The experimental study of learning and memory

Thorndike is famous for his experiments using A. Skinner boxes on pigeons B. puzzle boxes on cats C. mazes on rats D. fear learning in infants

B. puzzle boxes in cats

If a person learns a task by insight, we expect performance to: A. increase gradually across trials B. show a sudden jump on one particular trial and remain high thereafter C. show a sudden jump on one particular trial and then gradually decline D. remain relatively constant across all trials

B. show a sudden jump on one particular trial and remain high thereafter

Behavior without the brain: Spinal reflexes

Bell-Magendie (1800s) law of natural specialization 2 sets of fibers in the spinal cord -Sensory nerves: sensory information from PNS to spinal cord (dorsal) -Motor nerves: motor signals from spinal cord to muscles (ventral)

Much of the foundation for statistics and scientific methodology can be attributed to: A. Plato B. James C. Galton D. Darwin

C. Galton

What is Thorndike known for? A. The Skinner box B. Latent learning C. Puzzle boxes D. Foundation of statistics

C. Puzzle boxes

If you listen to a list of numbers, how many items will you likely be able to remember? A. About 15 B. exaclty 3 C. about 7 D. more than 20

C. about 7

The typical neuron receives input via the _____, processes information in the _____, and sends output via the ______. A. axon, soma, dendrites B. soma, axon, dendrites C. dendrites, soma, axon D. dendrites, axon, soma

C. dendrites, soma, axon

The principle that the mind and body exist as separate entities, each with different characteristics, governed by its own laws, is called: A. associationism B. contiguity C. dualism D. nativism

C. dualism

Rats that are exposed to circles and triangles for a month can learn to discriminate between these two shapes more quickly than rats not exposed to the shapes. This finding demonstrates A. learning specificity B. sensitization C. mere exposure learning D. priming

C. mere exposure learning

Which of the following is not one of Charles Darwin's proposed criteria for traits to evolve through natural selection? A. the trait must be inheritable B. the trait must vary C. the trait must be able to be learned D. the trait must make the individual more fit to survive

C. the trait must be able to be learned

Neurons

Cells that collect incoming information, process and respond by coordinating body responses. 100 billion neurons in human brain, each with ~1000 connections to other neurons

Who believed that rats were forming a "cognitive map" when they learned to navigate through a maze? A. Clark Hull B. Ivan Pavlov C. John B. Watson D. Edward Tolman

D. Edward Tolman

The 4 lobes of the cerebral cortex are the: A. frontal, cerebellar, hippocampal, and temporal B. Thalamic, parietal, cerebellar, and basal C. Occipital, basal, hippocampal, and thalamic D. Frontal, parietal, temporal, and occipital

D. Frontal, parietal, temporal, and occipital

Who came up with the idea of the magic number 7 for human working memory? A. Rumelhart B. Simon C. Estes D. Miller

D. Miller

If we were to cut the sensory fibers in your arm and you put your hand on a hot stove, you would: A. move your hand off the stove more quickly than normal B. feel more pain than usual C. Not be able to more your hand off the stove D. Not feel the pain

D. Not feel the pain

Which of the following is an example of habituation? A. As you go to bed, you partner starts snoring. The sound becomes more and more annoying as the night goes on. B. Your car spins out on the ice in the winter. Afterwards, you are much more nervous while driving. C. An experienced shepherd can quickly distinguish his sheep from one another. D. On your first day of class, you notice that your professor has a strong accent, but after being there for a while you no longer notice the accent.

D. On your first day of class, you notice that your professor has a strong accent, but after being there for a while you no longer notice the accent.

Which of the following properties was not one of Aristotle's ideas on how we develop associations? A. Contiguity B. Frequency C. Similarity D. Reflex

D. Reflex

What is latent learning? A. A form of classical conditioning B. Shaping C. Fear learning D. The fact that learning can occur without training or consequence

D. The fact that learning can occur without training or consequence

What is an example of habituation? A. getting used to braces B. getting used to the sound of construction outside your house C. getting used to the feel of a new pair of shoes D. all of the above

D. all of the above

The view that all the ideas we have are innate is called: A. associationism B. dualism C. empiricism D. nativism

D. nativism

Chemogenetics

Designer Receptors Exclusively Activated by Designer Drugs (DREADD) a designer receptor that will only respond to a particular drug (usually CNO) is introduced into neurons (via viral vector). CNO will only target that receptor. Can modulate neuronal firing for several hours.

Nervous system

Divided into 2 systems -Central nervous system (CNS): brain and spinal cord -Peripheral nervous system (PNS): nerve fibers that connect CNS to rest of body (from sensory receptors to CNS and from CNS to muscles)

Manipulation of neuronal function with drugs

Drugs- chemicals that change the body's biochemical functioning Can affect -Neurotransmitter release (e.g., amphetamines and increased DA release) -Neural firing (e.g., morphine or heroin into opiod receptor) -Neurotransmitter reuptake (SSRI = selective serotonin reuptake inhibitor)

W.K. Estes (1919-)

Early work with B.F. Skinner Later, finds new methods to interpret learning -Stimulus sampling theory: explained randomness in learning: Each stimulus has many elements; only a random sample (subset of elements) is associated with response in each trial. Statistical probability of a correct response. Helped establish mathematical psychology: mathematical equations to describe the laws of learning and memory

Charles Darwin (1809-1882)

English scientist Authored The Origin of Species (1859) Theory of natural selection: evolution of species -Trait inheritable (genes not discovered at that time!) -Trait must vary -Trait must increase reproductive success -Continuity between mental capacities of mammals and humans: Difference not of kind, but of degree

Sir Francis Galton (1822-1911)

English statistician, inventor, explorer... Studied human individual differences -Fascinated by the physically and mentally fittest -Found that attributes (e.g., height, blood pressure, memory skills) followed a normal distribution, a bell-shaped curve -Began eugenics movement: improving human hereditary traits through intervention (encouraged procreation among society's fittest) -Founded modern statistics Problem: Galton's research did not control for confounds (extraneous variables)

John Locke (1632-1704)

English thinker Subscribed to empiricism; all knowledge results from experience alone -Children are born as a "blank slate" and all have equal potential for knowledge -Strong influence for social philosophy; all should have opportunity for education and opportunity -The mind passively combines simple ideas into more complex ideas

Darwin's 3 Criteria for Traits to Evolve Through Natural Selection

Example: Giraffes 1. Inheritable Trait: Neck length 2. Natural variability: Short to long 3. Relevance to survival: Longer necks allow greater access to high branches of trees, and thus to leaves

Discrimination training

Feedback increases perceptual learning Learning specificity does not transfer automatically to discrimination of other stimuli e.g. dog show judge not good at discriminating among pigs

Jean-Baptiste Lamarck

French naturalist Acquired traits are passed from one generation to the next Ex. giraffe stretches neck to reach branches, next generation has long necks

Rene Descartes (1596-1650)

French thinker Founder of dualism Subscribed to a nativist view; what we know is innate Famous quote: "Cogito ergo sum" (I think therefore I am) Believed that animals lack a mind ("animal-machine")

Synapse

Gap (20 nm) between neurons; pass chemical signals across (neurotransmitters) -10^14 synapses in human brain -Each neuron has ~1000 connections with other neurons Presynaptic neuron: sending neuron Postsynaptic neuron: receiving neuron Receptors: molecules specialized to receive specific neurotransmitters

Hermann Ebbinghaus (1850-1909)

German psychologist Conducted first experiments on human memory, using himself as a participant Especially interested in forgetting (memory deterioration over time) -Used nonsense words -Examined how long it took him to relearn a previously learned list -Established the retention curve (% time saved to relearn a list)

Optogenetics

Get genetic code for opsin ion channels like chR2 (channelrhodopsin) into neurons via a viral vector. Can select specific type of neuron and specific location in the brain ChR2 responds specifically to blue light = if blue light shined, only neurons with chR2 will be turned on = manipulation of neural activity Precise temporal manipulation

Invertebrate model systems: aplysia

Gill withdrawal reflex -24 sensory neurons, 6 motor neurons When siphon is touched -sensory neuron fires -glutamate is released -receptors on motor neuron activated -action potential -muscles retract gill

Aristotle (384-322 BC)

Greek philosopher, taught by Plato Believed in "Tabula rasa" (Brain as a blank slate), knowledge comes with experience (i.e., empiricism) Also subscribed to associationism

Habituation in Aplysia

If repeatedly touched, habituation (gill withdrawal reflex weakens) Occurs rapidly after 10-12 touches, can last 10-15 minutes Synaptic depression: reduction of synaptic transmission, decreased glutamate release Homosynaptic inolves only synapses activated during the habituating event -Habituating in a siphon sensory neuron will not cause habituation in tail or mantle sensory neurons Habituation can last several days. Due to actual elimination of synapses (presynaptic sensory neurons)

Gordon Bower (1932-)

Interested in mathematical psychology and insight learning "One-step" model of human learning: going from ignorance to knowledge in a single trial Shows that individual performance, not just group performance is important

Non-associative learning

Involves only one stimulus at a time; simplest form of learning

Habituation

Lack of response to originally noticeable stimuli -A widespread, basic form of learning (even protozoa) -Automatic, reflexive Decrease in strength or occurrence of a behavior after repeated exposure to the stimulus that produces the behavior Examples: 1. Learning to ignore the hum of the air conditioner 2. Learning to ignore traffic sounds 3. Getting used to wearing glasses In a lab, a researcher can use simple, controllable measures such as the acoustic startle reflex to study this. Acoustic startle reflex: defensive response to a loud, unexpected noise, rat in experimental chamber will jump. If noise presented over and over again, startle response declines. Orienting response: innate response to a novel stimulus. Examples: infants turn their head and gaze at unfamiliar visual stimuli, dogs cock their head in response to novel stimuli Adaptive response, but can be dangerous -Boy who cried wolf

Spatial learning

Learning one's environment or surroundings -Tolman studies showing latent learning -Rats ran maze over 22 days -Group 1 received food for reaching food box on every trial over time, learned maze with few errors -Group 2 received no food for 10 days; on the 11th day, began to receive food. Show rapid learning and fewer errors than group 1

Associative learning

Learning to associate one stimulus with another or to a new response

Factors influencing rate and duration of habituation

Massed exposures (multiple, closely spaced sessions) to stimuli leads to faster habituation Spaced exposures: leads to better memory of the stimulus (and less response) after a period of no presentation Duration of habituation: few minutes or several hours, but not forever After a period of no stimulus presentation, spontaneous recovery (response reappearance) can occur Stimulus-specific: DOES NOT GENERALIZE TO OTHER STIMULI

Electroencephalography (EEG)

Measures electrical activity in the brain Event-related potentials (ERPs): averaged EEGs form a repeated event -Only the neurons specifically active for that event will show repeated activation Very good temporal precision but lack spatial precision

Neuromodulator

Modulate how neurons exchange messages -Some neurons (especially in the brainstem) send axons all over the brain. Can release neuromodulators into entire brain areas rather than a single synapse (e.g., acetylcholine) -Change the conditions for neural firing (e.g., number of receptors that have to be active before postsynaptic neuron can fire)

Sensory pathways into the brain

Most sensory information enters brain through thalamus Thalamus sends information to specialized cortical regions: Primary sensory cortices (A1, S1, V1) More advanced processing occurs in adjacent cortical regions

Neural plasticity and learning

Neural plasticity seems to be the physical basis of learning and memory -Experience induces neural plasticity -This neural plasticity alters the way the brain processes information -On the next experience, behavior will be altered For example, in rats raised in enriched environments, neurons make more synaptic contacts

Plasticity during development

Neuroimaging studies found that areas normally responding to visual stimuli in sighted people respond to sound and tactile information in blind people Opossum study: Kahn and Krubitzer (2002) Opossums blinded at birth show: -Shrunk visual area -Some neurons responding to auditory and tactile stimuli in that area -New multimodal area (X)

Neural plasticity

Neurons are extremely dynamic - the brain is constantly re-wiring itself based on experience The general term for this dynamic rewiring is neural plasticity Lots of ways to do this: -Make more/less transmitter -Have more/less receptors -Make synapses bigger/smaller -Eliminate synapses/make new synapses -And probably many more

Dishabituation

Novel stimulus can renew response. e.g. you make a new sound and your dog cocks his head again

Mere exposure learning

Occurs with only exposure to stimuli, no explicit prompting In studies: -Rats pre-exposed to shapes learned to differentiate shapes more quickly than rats with no pre-exposure -Over time, humans learned to distinguish a target scribble without feedback on accuracy Related to latent learning, original learning is not observed until a later time

Perceptual learning and cortical plasticity

Perceptual learning most likely cannot occur without a cortex. Cortex is necessary in order to learn about features of stimuli. Receptive field: the range of properties to which a neuron responds -an auditory neuron might have a range of 700-3000 Hz, with preferred frequency of 900 Hz -topographical organization in visual, auditory, and somatosensory cortices. Successive neurons respond to gradually increasing frequencies, intensities, etc. -Field can change with experience, contributing to cortical plasticity change in cortical organization as a function of experience Cortical changes after mere exposure Hodzic et al (2004) fMRI study -After 3 hours of fingertip tactile stimulation, participants showed increased discrimination -fMRI shows greater activation in the left somatosensory cortex =example of discrimination training Shortest distance between 2 points where you can distinguish the 2 points as distinct (tactile stimulation)

Erasmus Darwin (1731-1802)

Personal doctor of King George III of England Believed that species change over time Grandfather of Charles Darwin

How is LTP implemented in a neuron?

Postsynaptic receptors may become more sensitive to neurotransmitters (when A fires again, more response in B) Presynaptic neurons may release more NTs. Controversial, would mean that B releases a retrograde messenger back to A Permanent changes, sprouting of new synaptic contacts between co-activated neurons

Motor pathways from brain (outgoing)

Primary motor cortex (M1) gets input from frontal lobes, cerebellum, basal ganglia Sends output to the spinal cord via the brainstem Spinal cord activates motor fibers that control muscles

Perceptual Learning

Prior experience with a set of stimuli make those stimuli easier to distinguish from each other -Increased ability to make fine distinctions among highly similar stimuli Examples: -Chicken-sexers -Medical diagnosticians -Dog show judges

Priming

Prior exposure to a stimulus can improve recognition later -In humans, priming often studied with word-stem completion task -Fill in the blank (word stem completion) MOT____/SUP____ -Examples: motel, motor, moth/suppose, supper, supreme. If shown list of words prior to task, more likely to use them. -People with anterograde amnesia also show priming (implicit memory, not declarative memory)

B.F. Skinner (1904-1990)

Proponent of radical behaviorism Developed the Skinner box -Operant conditioning chamber for automated response learning -Later work advocates radical behaviorism consciousness and free will are illusions. Humans and other animals respond to learned responses to environmental stimuli

Edward Tolman (1886-1959)

Proposed that rats form cognitive maps: internal representations of environment -Rats in maze will find food from new start points Latent learning: learning happens in the absence of training or consequence -Laid groundwork for cognitive studies of learning

The Hippocampus and Spatial Learning

Rats with hippocampal lesions have difficulty learning spatial tasks Humans with medial temporal amnesia also may have problems with spatial tasks O'Keefe -Electrodes in rat's hippocampal area, some neurons fire only when rats move into specific locations = place cells -Place fields location associated with place cell's maximum response Place cell firing may be based on visual input but also direction or speed Some place fields are stable for months Provides basis for cognitive map (representation of spatial environment) Selectivity of place cell increases with experience. The place field becomes smaller and smaller, giving more precise location. Stability and selectivity of place cells firing correlates with spatial learning abilities Place fields are NOT maps -Place cells are not organized in a way that can be related to physical spatial positions. Neighboring place cells do not encode neighboring places. do not form two-dimensional map. -Same place cell responds to locations in many different environments and also responds to nonspatial cues (movements, odors) -How does it help navigation? Not clear (imagine a deck of cards with different street names and other features (dance steps, perfume), impossible to find your way)

Ivan Pavlov (1849-1936)

Russian physiologist Studies of dog digestion (Nobel Prize) lead to studies on learning -Classical conditioning; learning that one stimulus predicts another -Conditioned stimulus (bell, CS) predicts unconditioned stimulus (food, US) -Extinction: weakening a learned response (i.e., pairing a bell with no food) -Generalization -Similar sounds produce similar conditioned responses

Stimulating Neurons into Activity

Stimulation of neurons to observe corresponding behavior -A way to map cortical areas (homunculus in M1) -Transcranial magnetic stimulation (TMS): involves placing a magnet on the skull

Long-term potentiation

Strong stimulation of neuron A: robust response in neuron B Neuron B subsequently over-respond to weak stimulation of A= high stimulation of A potentiates B's response to subsequent stimuli = synaptic transmission is strengthened after recent activity = neurons change activity as a function of experience Long lasting change! can last for hours or days Electrical stimulation not required: as long as both neurons fire together, LTP can occur •What is the relationship of LTP to learning ? -Drugs that block LTP can impair learning -Rats bred to produce more LTP are better learners -No direct proof that LTP is related to learning!

David Rumelhart (1942-)

Student of Estes Disillusioned with symbol manipulation models With James McClelland, designed connectionist models -Cognition as networks of uninformed, unlabeled connections between "nodes" (simple processing units) -Models help integrate neuroscience with psychology

Neurophysiology

Study of neural activation One way to do this is through single-cell recording: microelectrodes implanted into an animal's brain; neuron's firing examined under different behavioral conditions

Difference Image

Subtracts image of baseline brain from the image of a brain engaged in specific activity -Images show which brain regions change or remain constant from baseline to activity -Valid for both techniques (PET and fMRI)

Herbert Simon (1916-2001)

Symbol-Manipulation Models -Gets Nobel prize in economy -A founding father of artificial intelligence (AI) -Develop a new computational approach to memory and cognition -Instead of SR associations, studies how the mind manipulates symbols Symbol-manipulation models: Models that store and manipulate symbols and labeled links

Observing Brain Structure and Function

Techniques to study brain/behavior relationships -Postmortem exams on people with behavioral data -Data on people with surgical or accidental brain insults -Imaging techniques -Experimental brain lesions in animals History Galen (Greek physician) -Correlations between mental abilities and head injuries Broca (French physician) 1880s -Aphasia case; Broca's area in left hemisphere Franz Joseph Gall (German physiologist) Pseudoscience of phrenology: Shape and bumps in skull as a measure of personality and abilities

Subcortical structures

Thalamus- receives sensory information; relays it to brain Basal ganglia- involved in learning skilled movements Hippocampus- linked to learning new facts, memory Amygdala- linked to emotion

Associationism

The principle that memory depends on the formation of linkages ("associations") between pairs of events, sensations, and ideas, such that recalling or experiencing one member of the pair elicits a memory or anticipation of the other 3 principles of associationism: 1. Contiguity: Nearness in time (temporal contiguity) or space (spatial contiguity) 2. Frequency: How often; the more often we experience events that are contiguous, the more strongly we associate them 3. Similarity: How similar; if two things are similar, the thought or sensation of one will tend to trigger a thought of the other

Spatial Learning in Wasps: Use of Landmarks

Tinbergen studies in wasps -Encircle wasp burrows with pinecones -After orientation flights, wasps leave to find food -Next, researchers move pinecone circles -Returning wasps search moved pinecone circles for burrows

Clark Hull (1884-1952)

Tried to develop a comprehensive mathematical model of learning -Variables = number of learning trials, frequency, motivation, incentive value of reward -Followers developed equations to describe basic components of learning -Ideas abandoned; cannot reduce all learning factors to a single equation

The human brain

Weight: 3 lbs (1350 g), approximately 2% of body weight Cerebral cortex: tissue covering top and sides of brain Divided into 4 lobes: frontal, parietal, temporal, and occipital Cerebellum: behind cortex -Important for coordinated movement -Involved in learning that requires physical action Brainstem: connects brain to spinal cord -Key in regulating automatic functions (e.g., breathing, body temperature)

Invertebrates

With recognizable, decentralized brains (e.g., octopus, bee) -Capable of maze learning, learning by observation With no recognizable brain (e.g., jellyfish, worm) -Can learn to avoid negative stimuli Simple invertebrate nervous systems are useful in research Nematodes ~300 neurons Octopus ~few hundreds neurons Human ~100 billion neurons

Sensitization

a startling stimulus leads to a strong response to a later stimulus. New stimulus would normally evoke a weaker response. e.g. strong electric shock increases rats' startle response to future loud noise for 10-15 minutes e.g. skin conductance response (SCR) in humans change in skin's electrical conductivity in response to emotion -Loud noise leads to strong SCR -Musical note leads to mild SCR -Loud noise. Then presents note. Now note elicits strong SCR Fewer trials needed than for habituation and long lasting memories (days or weeks) Not stimulus-specific (sensitizing stimulus can amplify response to any stimulus that comes later)

Reflex

an involuntary, automatic response to a stimulus ("hardwired"); present in all members of a species -Pavlov salivary responses to food -Newborn sucking reflex -Newborn palmar grasp reflex -Adult knee-jerk reflex -Eyeblink reflex

Memory

the record of our past experiences acquired through learning

Long-Term Depression

•Long-Term Depression (LTD) Neurons that do not fire together become disengaged. Synaptic transmission becomes less effective with experience Possible reasons: -Decrease in postsynaptic receptor sensitivity -Decrease in presynaptic neurotransmitter release -Retraction/dismantling of synaptic contacts between non-cooperating neurons