PSY 255- Exam 2

What are simple and complex cells in V1?

-Simple cells: Respond to oriented bar of light -Complex cells: not simple cells

Know over what frequency ranges we rely more on the place theory, vs. the temporal theory, vs. both.

?? Below 1,000 Hz: Rutherford's temporal theory Above 5,000 Hz: Bekesy's place theory Between 1,000 and 5,000 Hz: Both mechanisms code frequency (Remember, this is the range most important for understanding speech.)

Be able to decide which of two retinal ganglion cells will be firing faster based on their center/surround organization.

???

Dopamine may not only be associated with reward but maybe more with "being relevant to my interests."

???

How are simple cells built up out of inputs from center-surround retinal ganglion cells?

???

Sound is...

??? Sound: Pressure changes in a medium capable of being detected by human auditory organs. Sound= compression waves in a medium. That is why in space, no one can hear you scream.

Peptide neurotransmitters Some of their properties? Know some examples of each.

A short chain of amino acids E.g. oxytocin, endorphin Peptide neurotransmitters are strings of amino acids linked by peptide bond. Example: opioid neurotransmitters, such as endorphins

Amino acid neurotransmitters Some of their properties? Know some examples of each.

A single amino acid E.g. GABA, glutamate Most common neurotransmitters in the brain are amino acids. -Glutamate -GABA

What is the blind spot and why do we have it?

Blind spot is where the optic nerve attaches to the eye therefore any visual input being sent there we cannot see

Know about the retinotopic map and cortical magnification in V1. What is cortical magnification and how does it work?

Cortical magnification refers to the fact that the number of neurons in the visual cortex responsible for processing the visual stimulus of a given size varies as a function of the location of the stimulus in the visual field. Organization: Layers and columns, like the LGN Each layer contains a retinotopic map (like LGN) This retinotopic map devotes more space to stimuli in the fovea: cortical magnification ???

The place theory of frequency coding: How does it work? Over what ranges of frequencies does it work best? Why does it not work well at other ranges? What is some evidence we have for this theory? What is a cochlear implant and how does it work?

Different parts of the basilar membrane respond to different frequencies.(Notice that the area that is vibrating is larger for low-frequency sounds.) EVIDENCE: Neurons at different locations on the basilar membrane respond to different frequencies. In other words, different auditory neurons respond to different frequencies. Exposure to loud sounds at a particular frequency: -Causes hearing impairment at those frequencies -Destroys hair cells at a particular place on the membrane. HOW IMPLANTS WORK!!! Simulating auditory neurons at a location corresponding to a certain pitch.

What are reasons for thinking that dopamine neurons might be related to "wanting"

Dopamine has to do with motivation and motivation is Traditionally associated with "wanting"

What is the role of dopamine neurons in reward prediction error?

Dopamine often described as being associated with pleasure, but in fact seems to be associated more with reward. Dopamine traditionally associated with reward.However, there is some evidence to suggest that you get activation in the VTA in response to aversive stimuli.You also see patterns like reward prediction error to punishing stimuli. So perhaps dopamine is not all about reward?

Amine neurotransmitters Some of their properties? Know some examples of each.

E.g. acetylcholine, dopamine, serotonin Neurotransmitters that have a particular chemical structure We will discuss four major amine neurotransmitters: -Acetylcholine -Norepinephrine -Serotonin -Dopamine

The lateral geniculate nucleus

Each layer of the LGN gets input from only one kind of retinal ganglion cell. Each layer of the LGN gets input from only one eye Retinotopic map: Receptive fields of adjacent cells correspond to adjacent points on the retina. How is its layer structure organized? -Each eye has separate layer -Each type of retinal ganglion cell has separate layer -Layers have retinotopic maps: -Corresponding locations on the retina form columns across the layers

Effects on postsynaptic neuron (Receptor activation: What are agonists and antagonists? (Can also alter how strongly receptors respond) They can also change the postsynaptic neuron in a variety of ways via second messengers. Don't worry about this.)

Effects on the postsynaptic neuron: -Receptor activation: Agonists: Agonists are drugs that lock into a receptor and activate it just as the neurotransmitter itself would. -Partial agonist activates the receptor, but less strongly than the neurotransmitter would. Antagonists: Antagonists are drugs that lock into a receptor and do nothing. -Blocks the actual neurotransmitter from attaching to the receptor. (Can also alter how strongly receptors respond) -Postsynaptic intracellular processes

Drugs effects on presynaptic neuron:

Effects on the presynaptic neuron: -Transmitter production: A drug can increase or decrease how much neurotransmitter the presynaptic neuron makes. -Transmitter releas: A drug can increase or decrease the release of a neurotransmitter. -Transmitter clearance:A drug can increase or decrease the rate at which a neurotransmitter is removed from the synapse.

Acetylcholine Know about the properties and major functions of these neurotransmitters. What sort of drugs affect them?

First neurotransmitter discovered. Acetylcholine is the most common excitatory neurotransmitter in the peripheral nervous system -Involved in both voluntary and involuntary muscle movement Main neurotransmitter of parasympathetic nervous system It is also found in the CNS -Involved in memory, alertness -Decreased in people with Alzheimer's Drugs that affect acetylcholine include: nicotine, curare (poison arrows), botulism, sarin nerve gas

Know that sound frequency is related to perception of pitch. What is the approximate range of human hearing?

Frequency: Number of times per second the wave repeats Humans can sense 20-20,000 Hz range

Gas neurotransmitters How are they different from the other major kinds of neurotransmitters? Some of their properties? Know some examples of each.

Gas molecules that travel in and out of neurons -Gas neurotransmitters differ from other neurotransmitters: Instead of binding to receptors, they diffuse across cell membranes. -Activates second messengers in the neuron -Can also be a retrograde transmitter that travels from the postsynaptic neuron to the presynaptic neuron. -Plays an important role in learning and memory by changing the strength of synapses -Examples: Carbon monoxide, nitric oxide

What are the four major types of neurotransmitters

Gas neurotransmitters Amino acid neurotransmitters Peptide neurotransmitters Amine neurotransmitters

How does transduction work in the inner ear?

Hair cells' cilia wave back and forth with the movement of fluid and vibration of the basilar membrane As the cilia wave back and forth K+ ion channels open and close This causes the hair cell to release neurotransmitters that excite the auditory neurons

Ionotropic receptors

Is an ion channel that opens when a neurotransmitter locks in Quick but short response This makes the neuron -more likely to fire (excitation) -less likely to fire (inhibition)(Depending on what ions the receptor lets through)Work quickly, but effects don't last long

Olfactory receptor neurons (ORN)

Know that each ORN responds to a certain feature of a molecule, and the pattern of ORNs firing encodes the identity of the molecule - we do not have a different ORN for every molecule or smell -Neurons embedded in the olfactory mucosa Located at the top of the nasal cavity. Each dies after a few weeks. We have a continuous supply of mucus: -Completely regenerated every 10 minutes -Washes old molecules away so we can detect new ones -Protects CNS 350 types of ORN in humans

What is the center-surround organization of retinal ganglion cells? What does that mean?

Lateral inhibition: Inhibition that spreads laterally across a neural circuit Lateral inhibition creates "center-surround" ganglion cells

How does lateralization of visual information work?

Lateralization: Left visual field projects to the right hemi-retina and the right brain (and vice versa) (Mostly) travels through the LGN, located in the thalamus

Know the basics of the path of light through the eye and onto the retina.

Light passes through the front of the eye (cornea) to the lens. The cornea and the lens help to focus the light rays onto the back of the eye (retina). The cells in the retina absorb and convert the light to electrochemical impulses which are transferred along the optic nerve and then to the brain Light comes through the clear cornea Light travels through the pupil Light is focused by the lens Light is detected by the retina

What is a double dissociation? Be able to identify examples.

Looking at just patient DF we have a single dissociation: -Damage to a particular area of the brain causes one function to be damaged while another one is intact -Suggests that the two functions are independent of each other, BUT... -It could be that the function that was preserved is just easier than the function that was lost Damage to monkey's temporal lobe causes problems in object discrimination -Difficulty picking the rectangular object (which has the monkey treat). Damage to monkey's parietal lobe causes problems in landmark discrimination -Difficulty picking the object closer to the cylinder (which has the monkey treat) The monkey data shows a double dissociation -Damage to one area of the brain causes function A to be damaged while function B is intact -Damage to a different area of the brain causes function A to be intact while function B is damages -Strongly suggests that the two functions are independent of each other, and one is not just easier than the other

Norepinephrine Know about the properties and major functions of these neurotransmitters. What sort of drugs affect them?

Main neurotransmitter of the sympathetic nervous system Arousal and alertness -Plays important role in fight-or-flight response -Lowest levels when we are asleep Focuses attention and enhances memory Mood Drugs that affect norepinephrine include: Wellbutrin, tricyclic antidepressants, SNRI antidepressants, beta blockers

How do drugs of addiction mess with the reward prediction system?

Many (most? all?) drugs of addiction affect dopamine One possible mechanism is by affecting reward prediction error. -With a drug of addiction the burst of dopamine when you get the drug never goes away.

Which has more convergence, rods or cones? What are some of the consequences of this fact?

Many rods connect to one ganglion cell Few cones connect to one ganglion cell. This is one reason rods are more sensitive to light than cones.(The rods are also intrinsically more sensitive than cones, responding to as little as a single photon.) The low convergence in cones (especially the fovea) gives cones a greater ability to detect details.

Glutamate Know about the properties and major functions of these neurotransmitters. What sort of drugs affect them?

Most common excitatory neurotransmitter in CNS Over 90% of synapses in brain are thought to contain glutamate.Does most things.Very important in synaptic plasticity ➔ learning and memory.Drugs that affect it include ketamine and alcohol.

GABA Know about the properties and major functions of these neurotransmitters. What sort of drugs affect them?

Most common inhibitory neurotransmitter in CNS GABA is the most common inhibitory receptor in the brain. Also does a lot of things. High levels of GABA in the brain tend to be sedating and anxiety-reducing. Drugs that affect it include benzodiazepines (e.g. Valium) and alcohol.

Where are most of the dopamine neurons in the brain located?

Most of these are in one of two locations in the midbrain: -Substantia nigra -Ventral tegmentum (VTA)

What is convergence?

Multiple rods/cones can connect to one ganglion cell

What is the reason for thinking opioids play a role in "liking" and dopamine in "wanting" Be able to describe the results of the experiments we discussed in class on rats with their opioid system disabled vs. rats with the dopamine system disabled.

OPIOIDS: Studies have found that using drugs to increase the activity of opioid receptors in the nucleus accumbens of rats: -Increases their feeding behavior (especially for favorite foods) -Increases their expressions of "liking" Blocking these receptors: -Decreases preference for favorite foods -Decreases expressions of "liking" DOPAMINE: is traditionally associated with "wanting" A classic study found that rats with their dopaminergic neurons destroyed: -Showed the normal "liking" reactions to having sucrose placed in their mouth -But they weren't eating of their own accord. -(Whereas rats with opiate system knocked out eat but don't show the evidence of liking)

What are some of the areas in the brain involved with smell? Why does smell seem to have a heightened association with emotion and memory?

Olfactory bulb Piriform cortex (primary olfactory cortex) Amygdala (deal with memory and emotion) Hippocampus (deal with memory and emotion)

A neurotransmitter has many different kinds of receptors.

One reason a neurotransmitter does so many things Different functions, different anatomical distributions -Thus different receptors tend to be associated with different functions (but not always in a tidy manner). A drug can affect different kinds of receptors for a neurotransmitter in different ways A drug can affect some receptors for a neurotransmitter more than others This is why different drugs that affect the same neurotransmitter can have very different effects -E.g. LSD, Prozac, and triptans

Serotonin Know about the properties and major functions of these neurotransmitters. What sort of drugs affect them?

Only about 200,000 serotonergic neurons in brain (out of about 80 billion) Mostly in raphe nuclei in the brain stem Plays a role in mood, perception, nausea, controlling pain Drugs that affect serotonin include: -Many antidepressants such as SSRIs -Most hallucinogens such as LSD -Many antipsychotics -Many migraine medications (such as triptans)

Dopamine Know about the properties and major functions of these neurotransmitters. What sort of drugs affect them?

Only about 500,000 - 1,000,000 dopaminergic neurons in the brain, out of about 80 billion total neurons. Most of these are in one of two locations in the midbrain: -Substantia nigra -Ventral tegmentum (VTA) Drugs that affect dopamine include: -many drugs of addiction -L-DOPA (treats Parkinson's) -Wellbutrin and some other -anti-depressants anti-psychotics (especially first-generation antipsychotics)

What are reasons for thinking that dopamine neurons might be more associated with "seeking" or "working for" a reward rather than "wanting" it? (Be able to describe the results of the experiment with smokers we discussed in class)

Other studies suggest dopamine is less about "wanting" and more about willingness to work to get something.For example, a study on smokers found that when their dopamine synthesis was temporarily decreased: -Their self-reported pleasure in smoking did not decrease -Their self-reported craving for smoking did not decrease -However, how much work they were willing to do to get a cigarette did decrease.

What are the following parts of the ear? What function do they serve?

Pinna: Visible external ear -Funnel, amplify and localize sound -Keeps our glasses from falling Eardrum: (Tympanic membrane) -Vibrates in response to pressure changes -Transmit sound to middle ear Middle ear bones (do not need to know names of the bones): Little bones amplify sound before transmission the inner ear. Oval window: attached to stapes Transmits vibrations to cochlear fluid Cochlea: Where transduction takes place! Basilar membrane: Vibrates in response to sound (inner ear) Hair cells: attached to basilar membrane (inner ear) Move because of vibrations in the fluid Transduction! As the cilia move back and forth, ion channels open and closePotassium ions rush in, creating electrical charge. Hair cell releases neurotransmittersThese make the auditory nerve fire.

What is the distinction between "liking" and "wanting"?

Psychologists make a distinction between "liking" and "wanting". -"Liking" is how much you enjoy something. -"Wanting" is how compelled you are to do it. E.g smokers often report they don't especially like smoking, but they can't stop. Traditionally, the opioid system has been linked to "liking" and the dopamine system to "wanting." -It appears to be more complicated than this. -But, there is some truth to it as well.

How does the number of olfactory receptors relate to the organism's sensitivity to smell?

Rats are 8 to 50 times more sensitive to odors than humans. Dogs are 300 to 10,000 times more sensitive. However, individual receptors for all of these animals are equally sensitive: only one molecule is required. The difference lies in the number of receptors they each have. -Humans have 5-10 million -Cats have 45-80 million -Dogs have 100-220 million (or more?)

What is the path of information through the visual system to the point where it splits into the dorsal and ventral streams?

Retina Retinal ganglion cells LGN V1 V2 V3 90% of ganglion cell axons go to the lateral geniculate nucleus (LGN) in the thalamus10% go to other structures The most important is the superior colliculus (SC; important for eye movements) Lateralization: Left visual field projects to the right hemi-retina and the right brain (and vice versa) (Mostly) travels through the LGN, located in the thalamus Cells in V1 respond to particular points in the visual field Multiple types of cells in V1: -Respond to particular colors -Respond to particular distances -Respond to particular sizes -Simple cells: oriented bars -Complex cells: not simple cells

Know the anatomy of the retina

Retinal ganglion cells: The rods and cones connect ultimately connect to retinal ganglion cells. The ganglion cell passes the information from the rods and cones to the brain. When a ganglion cell fires, we see light. Each have their own receptive field Bipolar cells Rods and cones Fovea- a small depression in the retina of the eye where visual acuity is highest. The center of the field of vision is focused in this region, where retinal cones are particularly concentrated. Blind spot: Where the optic nerve attaches to the eye Optic nerve: The axons of the ganglion cells form the optic nerve. Which transmits the information from the retina to the brain.

Rods vs cones:

Rods: Mostly in periphery High light sensitivity Don't detect color Many rods connect to one ganglion cell lower ability to detect details Cones: Mostly in center Lower light sensitivity Detect color Few cones connect to one ganglion cell. greater ability to detect details

Metabotropic receptors

Sets off a chain of protein second messengers Can open ion channels Can make many other alternations to postsynaptic neuron like: -make new ion channels -cause the neuron to make new proteins Can amplify response Slow but longer response

What are top-down and bottom-up processing? Be able to identify examples.

TOP-DOWN: Information processing guided by higher-level mental processes as we construct perceptions, drawing on our experience and expectations. (uses background knowledge to influence perception) ex. knowing it should look like a cube so we see it as such BOTTOM-UP: Analysis of the stimulus begins with the sense receptors and works up to the level of the brain and mind. (no previous idea of what you're looking at so you have to let the stimulus explain what you're looking at) ex cockpit of a plan

What is the relationship between smell and taste?

Taste and smell are very closely linked. -Volatile compounds in food travel from mouth to nose -(Smell of food doesn't come through nose, but is nose is stopped up the air doesn't flow.) -Many connections between the taste and smell pathways in the brain.

What is transduction? Where and (roughly) how does it happen in the eye?

The rods and the cones are where transduction happens. Transduction is the process of converting information from the outside world into the electrical and chemical signals of our nervous system. The sensory receptors that we have determines what we perceive. -E.g. how many colors you can see depends on how many types of cones you have.

The temporal/frequency/volley theory of frequency coding How does it work? What is the role of the volleys in this theory? Over what ranges of frequencies does it work best? Why does it not work well at other ranges?

Theory: -Basilar membrane vibrates at the sound's frequency -Every vibration causes auditory nerve cells to fire -Firing rate signals frequency Problem: -Max firing rate is 1,000 times/sec (1,000 Hz) Solution: -Volley principle -Neuron does not fire with every sound wave -When it does, it fires at the peak pressure -In combination they are firing with every peak

Opioids Know about the properties and major functions of these neurotransmitters. What sort of drugs affect them?

Two major roles of opioid neurotransmitters in the brain: -Control of pain -Pleasure/ Liking Drugs that affect opioid receptors include heroin, morphine, opium, OxyContin...

What are some of the areas in the ventral stream? What sort of visual input are they responding to?

V4- Contains cells sensitive to curved edges and simple shapes inferotemporal cortex (IT)- responds to more complex shapes over a larger part of the visual field than V4 Fusiform face area- responds best to faces. -Although also active in other tasks that involve subtle distinctions, e.g. bird experts identifying different kinds of birds

What are the dorsal and ventral pathways?

What lobes are involved in each of the two pathways? What visual tasks are they responsible for? What is some evidence for this in brain-damaged patients? What is some evidence for this in normal subjects? DORSAL Neurons in MT are strongly selective for motion Neurons in intraparietal sulcus play a role in visually guided action: -E.g. eye movements -E.g. reaching parietal lobe "where" tasks ??? VENTRAL V4 - the first area in the visual cortex exclusively part of the ventral stream temporal lobe "what" pathway ???

Why do we need to amplify sound in the middle ear?

Without amplification, only 1% of the vibrations would be transmitted.

What is prosopagnosia?

a neurological condition characterized by the inability to recognize the faces of familiar people.

How is reward prediction error related to classical conditioning?

classical conditioning is an example of a positive reward prediction error

What are the two basic kinds of receptors?

ionotropic receptors Metabotropic receptors

Olfactory mucosa How often does the mucus replace itself? Why?

is located in the upper region of the nasal cavity and is made up of the olfactory epithelium and the underlying lamina propria, connective tissue containing fibroblasts, blood vessels, Bowman's glands and bundles of fine axons from the olfactory neurons. ????

Smell and taste are chemical senses

meaning actual molecules from the substance we are smelling/tasting bind to receptors.

What is reward prediction error? Be able to describe what is happening with reward prediction error - and dopamine neurons: Before conditioning After conditioning when expected reward is received After conditioning when expecting reward is NOT received.

the difference between the actual reward received versus the amount of predicted or expected reward. For example, when an animal presses a lever and receives an unexpected food reward, a positive prediction error occurs (a better than expected outcome) and the animal learns to press the lever again. By contrast, when an animal expects to receive a reward from pressing a lever but does not receive it, a negative prediction error occurs (a worse than expected outcome) and the animal will subsequently be less likely to press the lever again. Reward prediction error can thus serve as a kind of "teaching signal" that helps the animal to learn to behave in a way that maximizes reward. As the response becomes expected, the prediction error drops to zero. DOPAMINE: You also see patterns like reward prediction error to punishing stimuli.

Know about MT's role in motion processing.

the primary sources of visual motion information that are used to construct the motor commands for pursuit. This motion information is also used to adjust the size of saccades made to moving visual targets. ???