PSYC 344

What are the dendrites? What do they do?

* branches surrounding the body of the cell
* responsible for collecting information from neighboring cells

What is the cell body of the neuron? What is its function?

* located at the center of the dendrites
* responsible for manufacturing NTs and integrating signals received

What are the axons? What are they responsible for?

* part of the neuron surrounded by the myelin sheath, connecting the body of the cell to the axon terminals
* responsible for signal transmission

What are the axon terminals? What are they responsible for?

* located at the ends of the axon, branching out to connect to other neurons’ dendrites
* responsible for releasing NTs into the synaptic cleft

What is the myelin sheath? What is it responsible for?

* the insulating cells surrounding the axon
* responsible for increasing transmission speed

When does myelin development end?

ends in most people’s mid-20s

What is the neuron membrane? What does it do?

* the membrane surrounding the neuron and covered by the myelin sheath
* responsible for allowing specific molecules into the cell and preventing others from coming in or leaving

What molecules do the neuron’s membrane allow to flow freely? Which ones are blocked?

* O2, CO2, and glucose flow freely
* water and other polar molecules are blocked

How are ions and other molecules allowed through the membrane when needed?

through channels, gates, and pumps

What are the two types of gradients?

* electrical: same charges repel & opposite charges attract
* concentration: molecules move from high to low concentrations

What is the resting potential of a neuron? What is the mV value at rest? How are A-, K+, Na+, and Cl- arranged?

* resting potential: when the neuron is at rest and the inside of the cell is more negatively charged than the fluid outside the cell
* -70 mV
* A- & K+ are more concentrated inside the cell at rest
* Na+ & Cl- are more concentrated outside the cell at rest

What is the status of the Na+ channels at rest? Does Na+ want to move?

channels are closed

Na+ is concentrated outside and wants to come in because of concentration and electrical gradients

What is the status of the K+ channels at rest? Does K+ want to move at rest?

channels are partially closed

K+ is concentrated inside and does not want to move

concentration and electrical gradients are balanced (one in and one out)

What is the status of Cl- at rest? Does it want to move?

Cl- concentrated outside

doesn’t want to move; gradients balanced

concentration gradient wants in but electrical gradient wants out

What are graded potentials?

localized changes at one point along the neuron that do not cross threshold

What is depolarization?

neuron charge becomes more positive

neuron is more likely to fire

What is hyperpolarization?

neuron charge is more negative

neuron is less likely to fire

What are action potentials? What charge must be passed?

* all-or-nothing response in which the depolarization threshold must be passed
* occurs at -50mV or higher

What occurs during the first step of the action potential? (aka how does Na+ trigger an AP?)

Na+ channels open

Na+ enters axon and rapidly depolarizes neuron

What occurs at the peak of the AP (aka when the voltage is at +20mV)?

Na+ continues moving in

K+ channels begin to open

What happens during the re-polarization phase of the AP?

Cl- ions come in when neuron is depolarized

ions in and out of the neuron are all unbalanced

When does K+ move out of the cell during the AP?

it moves out during the absolute and relative refractory periods

What is the refractory period?

* a period during and immediately following an AP in which another AP cannot be triggered
* Na/Cl pumps restore the polarity in the cell

What is the purpose of saltatory conduction?

* it increases the speed of transmission by making AP’s more efficient along the axon
* AP occur only at gaps/nodes between the myelin sheath
* AP at one node triggers the opening of Na+ channels at the next node

What is the pre-synaptic membrane?

membrane that encloses the molecules that transmit chemical messages

What are vesicles?

packaging for the neurotransmitters

What is the synaptic cleft?

the space between neurons where the NTs are released

What is the post-synaptic neuron?

the neuron that contains receptors to receive NTs

What are the receptors/binding sites?

located on the post-synaptic neuron and function as a lock and key mechanism with NTs

What are the 6 steps of neurotransmission?

1. NTs are manufactured in the cell body and in the axon terminals
2. AP is propagated along the pre-synaptic neuron → Na+ influx leads to opening of Ca2+ channels
3. Ca2+ influx triggers NT release (vesicles move to axon terminals and release NTs to the cleft)
4. NTs bind to receptor sites on post-synaptic neuron
5. binding triggers depolarization or hyperpolarization
6. NTs are inactivated

What are the 3 ways that NTs can be deactivated?

1. diffusion: NTs move into the intracellular fluid outside the synaptic cleft
2. degradation: enzymes in the synaptic cleft degrade the NTs
3. reuptake: the pre-synaptic neuron picks NTs back up into axon terminal

What is the function of acetylcholine? (4) Where can if be found? What is a clinical example of its importance?

* PNS motor control, sleep, learning, memory
* located throughout the CNS and PNS
* ex: Alzheimer’s (many meds act of ACH → many neurons with ACH receptors die off → meds act at ACH to prolong higher functioning)

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What are the functions of dopamine (4)? What is a clinical example?

* CNS motor control (aka how much force behind movements), reinforcement/pleasure, memories, planning
* ex: schizophrenia (brain has too excess dopamine → leads to hallucinations → meds interrupt binding process)

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What are the functions of norepinephrine and epinephrine (3)? What is a clinical application?

* arousal/attention, sexuality, appetite
* ex: ADHD (meds increase NE in brain to increase attention)

What are the functions of serotonin? (5) What is a clinical application?

* regulates mood, sleeping, appetite, pain, arousal/attention
* ex: depression (the interaction with depression is more complex; serotonin impacts other things that impact depression)

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What are the functions of glutamate? (1 general, 1 specific) How does alcohol impact it?

* general: excitatory
* specific: opens Na+ channels to increase likelihood of AP
* alcohol inhibits glutamate

What is the function of GABA? (1 general, 1 specific) What is a clinical application?

* general: inhibitory
* specific: opens ion channels that are more likely to hyperpolarize neurons
* ex: seizures are an Imbalance between GABA and glutamate (too many excitatory signals)

What are the functions of opioids (2)

1. sensing pain
2. nausea

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What are the functions of oxytocin (3)? What is a clinical example?

* social bonding, initiation of labor, milk release
* ex: autism (difference in social interaction/bonding)

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What are the functions of corticosteroids/cortisol? (2) What is a clinical example?

* impacts stress response, increases arousal and awareness
* ex: PTSD (levels are chronically high → can become toxic)

How is the brain hierarchically organized?

* parts at the base of the brain are responsible for more basic functions (reflexes, essential functioning, etc.)
* the more superior portions of the brain are for higher complexity processing

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What are the three meninges? What are their function?

* dura mater
* arachnoid mater
* pia mater

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* function: to cover the brain and spinal cord and protect them

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What are the characteristics of the dura mater?

* hard, durable
* outer layer by the skull

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What are the characteristics of the arachnoid mater?

* web-like filaments
* vascularized
* fragile

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What are the characteristics of the pia mater?

* thinnest layer
* sits on the surface of the brain

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What are subdural and subarachnoid hematomas? What does severity depend on?

* occurs when there is blood pooling under the dura mater or the arachnoid mater that increases pressure on the skull and on the brain
* more severe if its in the deeper layers

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What are the ventricles in the brain? How did they form? What is their function?

* 2 lateral ventricles, 3rd ventricle, 4th ventricle
* formed out of the hollow space when the NS develops in the first trimester
* function is manufacture CSF to support and maintain the brain and spinal cord

Where is CSF made? Where does it go when it’s used?

* continuously made in the choroid plexxus
* drains into the venous system when it’s used

What is hydrocephalus? How does it differ between infants and adults? What are the signs of hydrocephalus in adults?

* happens when the ventricles swell and push away the brain and the skull bones
* in infants, this enlarges their head because the sutures are not fully formed → needs to be drained
* in adults, the pressure can harm the brain and the skull → pressure needs to be released
* signaled by the three W’s (wet, wobbly, wacky)

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What are the three main sections of the hindbrain?

* medulla
* pons
* cerebellum

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What are the functions of the medulla? (5)

* cardiovascular function
* respiration
* muscle tone
* reflexes (like gagging)
* arousal

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What are the functions of the pons? (2)

* regulates sleep cycle
* arousal

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What are the functions of the cerebellum? (5) What is special about the cerebellum? What condition may it relate to?

* coordinated movement
* posture
* balance
* motor timing
* some cognitive function (attention)

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* connected with all other parts of the brain
* may relate to autism and some social/emotional function

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Why is arousal a common thread between the functions of the hindbrain and the midbrain?

the reticular formation, which is responsible for arousal, stretches along both the midbrain and hindbrain

What are the three main parts of the midbrain?

* superior colliculi
* inferior colliculi
* tegmentum

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What is the function of the superior colliculi?

visual reflexes

What is the function of the inferior colliculi?

auditory processes

What are the functions of the tegmentum? (4) What is included in it and how does it relate to Parkinson’s?

* arousal
* sleep
* dopamine
* neurons important for motor functioning

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* includes the substantia nigra
* the neurons In this region die during Parkinson’s and manifest as motor deficits

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What four structures are a part of the forebrain?

1. thalamus
2. hypothalamus
3. limbic system
4. basal ganglia

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What are the functions of the thalamus? (4)

1. sensory information for all but smell
2. motor function
3. arousal (attention and wakefulness)
4. relays information between sensory receptors and specific areas in the cortex

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What are the functions of the hypothalamus? (4)

1. homeostasis (temperature, sleep, hunger, thirst)
2. motivational states
3. controls autonomic systems
4. controls endocrine systems

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What are the functions of the limbic system? (4)

H. homeostasis and autonomic response (hypothalamus)

O. olfaction (olfactory bulbs)

M. memory formation (hippocampus, septal nucleus, mammary bodies)

E. emotion (amygdala attaches emotional significance to sensory stimuli and memory (especially fear))

How does PTSD relate to the limbic system?

* responsible for some of the underlying mechanisms of PTSD
* parts work together for good and bad

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What are the functions of the basal ganglia? (3)

1. motor movement (regulates force)
2. regulates emotion
3. regulates attention

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What clinical connections does the basal ganglia have?

* Parkinson’s (many dopamine cells and connections to substantia nigra)
* Huntington’s
* Tourette’s (neurons are too excited)
* ADHD
* OCD

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What are the grooves of the cortex called?

sulcus/sulci

What are the ridges/bumps of the cortex called?

gyrus/gyri

What is the purpose of the gyri and sulci?

folding helps to increase surface area

What type of neural tissues is the cortex? Why?

* grey matter
* mostly cell bodies and dendrites which are unmyelinated

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How is the cortex organized into layers? What happens if this development goes wrong?

* some send information
* some receive information
* some integrate information

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* if migration of neurons goes wrong in-utero → seizures may occur because the neurons are not in their intended layer

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What are the hierarchy in the cortex?

* primary areas: mostly sensory-motor processes
* secondary & tertiary areas: integration and complex mental processes

What are the 4 lobes of the cortex?

frontal, parietal, temporal, occipital

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there’s a right and left for both (different responsibilities for each side)

What is the V1 part of the occipital lobe?

* region surruonding the calcarine sulcus

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What is the dividing line of the occipital lobe from other parts of the brain?

posterior to the parieto-occipital sulcus

What is the function of the V1 area?

* the first place where visual information goes to

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How is the V1 organized? Why?

* topographically
* most interior occipital does peripheral vision
* most exterior occipital does center vision
* largest area of V1 dedicated to processing center of visual field → allows for greater acuity

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How is visual information received and sent to the V1?

* each side of the V1 area receives info from the contralateral visual field
* both eyes get information from both sides of vision field
* right hemisphere gets info from left visual field and vice versa

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What kinds of information does the V1 process?

* processes lines and angles
* very basic processes

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What happens if half of V1 is damaged? How does this usually happen? What happens if both sides are damaged?

* homonymous hemianopia: loss of half of visual field
* happens due to stroke
* if both are damaged → total loss of visual field

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What are the functions of V2? (what does it process?)

* processes color (differences in shades)
* processes orientation (curves and angles)

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Where is V2 located?

surrounding the V1

What happens if V2 is damaged?

* cerebral achromatopsia: loss of color cognition due to damage to brain parts that process color
* no color thinking
* only see and imagine in shades of gray

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What is the dorsal stream? What lobe is it located in?

* the “where” pathway
* in the parietal lobe

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What are the responsibilities of the dorsal stream? (3)

* location recall
* visualizing location
* moving through spaces

What happens if there is damage to the dorsal stream?

* akinetopsia: inability to perceive movement and location

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What is the ventral stream? Which lobe is it located in?

* the “what” pathway
* in the temporal lobe

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What is the responsibility of the ventral stream? (1)

identifying what is seen

What happens if there is damage to the ventral stream? How can this condition vary by person?

* visual agnosia: inability to perceive/identify a visual stimulus
* some people may identify people but not objects and vice versa (controlled by different places in the brain)

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How is the frontal lobe involved in visual processing? Where is it located?

* uses memory to interpret and predict visual stimuli
* processes autobiographical info
* where the ventral stream and dorsal stream meet

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What are the secondary and tertiary areas inside the occipital lobe responsible for?

more complex processing

(color, simple shapes, motion, dynamic form)

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dynamic form = the form of a unitary object with the shape changing with movement)

What sense is the highest proportion of the cortex dedicated to?

* vision
* multiple regions outside the occipital lobe that respond to specific aspects to visual world

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What is the anterior boundary of the parietal lobe?

central sulcus

What is the posterior boundary of the parietal lobe?

parieto-occipital lobe

What is the primary area division line of the anterior parietal lobe?

postcentral gyrus

What is the secondary and tertiary dividing line for the posterior parietal lobe?

everything behind the postcentral gyrus

What is the function of the post-central gyrus (aka anterior parietal lobe)? (3)

* body senses in primary somatosensory area (pain, touch, pressure, temp, proprioception)
* interpreting other sensory info (vision/sound)
* sends info to motor areas (frontal lobe) to provide info about body position to guide movement

How is the post-central gyrus organized? What depends on the amount of tissue organization?

* primary somatosensory area organized somatotopically organized
* organized so that lots of tissue is dedicated to specific areas (homunculus)
* sensory thresholds depend on how much cortex is allotted for the body region
* organized contralaterally (right side sensations processed on left side of brain and vice versa)

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What happens if the post-central gyrus is damaged with lesions? (4)

* changes in somatosensory threshold (requires more pressure to register sensation)
* astereagnosia: challenges with using touch to recognize objects
* Impaired position sense
* somatosensory agnosia (such as finger agnosia)

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What is the purpose of the bimodal neurons in the posterior parietal lobe? What pathway does this relate to?

fire in response to activation of two sensory systems

* combines somatosensory and visual / somatosensory and auditory
* “where” pathway for vision and sound

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