Glossary of Phys Neuro Part II
Other Decks By This User
- if you are blind in only one eye? what do you lose?
- monocular vision on that side which is the lateral 30
- process of phototransduction in light and dark
- in dark there is alot of cGMP in photoreceptor so this opens Na/K channels allowing Na to come into photreceptor to depolarize it and cause more glutamate to be released
When Light comes in, it changes the conformation of opsin (Photopigment molecule) this activates transducen which activates phosphodiesterase which in turn decreases cAMP so Na/K channels close and photoreceptor hyperpolarizes causing a decrease in glutamate release
- what has more discs rods or cones?
- rods meaning there are more photopigments and more sensitivety to light so you can see better at night
- describe neural processing of retina
- photoreceptors contact bipolar cells and bipolar cells synaptically contact ganglion cells.
ganglion cells make up optic n.,chiasm, and optic tract that leave the eye
- only retinal cells that provide visual signal to brain
- ganglion cells (they become optic n. tract, and optic chiasm)
- describe retinal ganglia visual receptive field
- 2 types of retinal ganglia
- 1.on center ganglion cells- where if light falls on center of receptive field, neuron is excited. If light falls on surrounding, neuron is inhibited.
2.Off center- If light falls in center, neuron is inhibited. If light falls on the surrounding, neuron is activated
Ganglion cells fire most actively when the contrast is the highest
- what does each hemiretina see in left eye?
- nasal hemiretina sees left visual field, temporal hemiretina sees right visual field
- What does each hemiretina see in the right eye?
- the nasal hemiretina sees the right visual field and the temporal hemiretina sees the left visual field
- since the L brain sees right visual field and the R brain sees the L visual field, how does this happen
- at the optic chiasm the nasal hemiretina crosses over
- lesion in L optic n.
- lose vision in L eye
only lose monocular vision
- Lesion at optic chiasm
- lose crossing fibers so lose peripheral vision get tunnel vision
- lesion of L optic Tract
- lose R visual field
- damage to parietal lobe what visual field is affected
- since visual field is flipped you lose bottom of receptive field
pie in the sky defecit
- Pathway of pupillary light reflex
- retina->optic n.->optic chiasm->optic tract
->pretectal n.in dorsal midbrain->edinger westphal n.->oculomotor n.->ciliary ganglion->circular m. of iris
- transect L optic n. shine light into L eye
- direct response-none
consenual response-none bc pathway is blocked
- transcet L optic n. shine light into R eye
- Direct respone-constricts
- Transect L oculomotor n.
Shine light into L eye
- direct respone-none
consenual respone-yes R consticts
- Transect L occulomotor n. shine light into R eye
- direct response yes
- what CN can be tested by looking at the eyes?
- Mydriasis pathway for response
- hypothalmus and midbrain -> IML of SC -> superior cervical ganglion ->radial muscle contracts and this pulls on the pupil to dialate it
- what innervates sensory for cornea?
- Pathway for corneal blink reflex
- someone touches cornea (ouch!) -> V1 ->spinal trigeminal n. -> facial n.
-> orbicularis oculi m to cause blink
- What initiates blink reflex?
- touch cornea, bright light (due to sensory component of optic n.) or loud sounds (caused by CN VIII)
- Lesion in R V1
Touch R eye
whats the response?
- no direct or consenual respone bc never felt it since sensory component is gone
- Lesion in R V1
Touch L eye
Response of blink reflex?
- Both eyes blink
- Cut R facial nerve
Touch R eye
- R eye wont blink but L eye will
- production of aqueous humor is greater than the drainage causing increased intraocular pressure that damages optic disk which injures ganglion cell and causes blindness
- Color blindness
- occur mainly in men bc X linked
cant distinguish between red and green
- Clouding of the lens
common in old people
- Types of neurons in primary visual cortex
- simple cells
direction selection neurons
- describe simple cells in primary visual cortex
- differs from ganglion cells bc see lines rather than circles
involved with determing motion of an object
- direction selective neurons in primary visual cortex
- responds to direction of a line moving across the receptive field in a certain direction only
- What 2 cells types of the primary visual cortex are involved with determining motion of objects
- simple cells and direction selective neurons
- describe complex cells in primary visual cortex
- determines shape of objects
- Describe blob cells of primary visual cortex
- have circular fields like ganglion cells
Blob cells determine color of object
- Describe the overall organization of primary visual cortex
- four main cell types are organized into cubes of cortex. Each cube analyzes a particular point in space and determines all of the important info of that area. Info from the cubes then flow to a higher order association cortex to interpret what you see. Info then goes into either the dorsal or ventral pathway
- Dorsal pathway of primary visual cortex
- goes to parietal lobe. It detects the location of the objects in space and allows detection of motion. Bilateral lesions make it imposible to percieve moving objects
- Ventral pathway of priamy visual cortex
- courses from the primary visual cortex toward the temporal lobe. It identifies objects. Lesions in this region lead to loss of recognition
- what does frequency of sound waves determine?
- pitch of sound you hear
- What does amplitude of sound waves determine?
- loudness of sound
- outer ear structures
extneral auditory canal
- gathers sound waves. helps determine location of sounds in space
- external auditory canal
- conducts sound waves to tympanic membrane
- tympanic membrane
- eardrum. vibrates at freqency of sound wave. conducts sound waves to middle ear by converting sound energy to mechanical displacements
- Middle Ear structure
- made of 3 small bones (malleus,incus, and stapes) the maleus is attached to the tympanic membrane and the stapes is attached to the oval window. the incus connects the malleus and stapes
- How does middle ear amplify sound?
- It acts as a lever system by acting as a lever and mostly by the force of sound waves that is pushed from the large tympanic membrane to the small oval window. Causes a 20x amplification
- Purpose of auditory eustachian tube in middle ear
- connects middle ear to pharynx and maintain middle ear at atmospheric pressure. tube is normally closed so with changes in altitude causes difference in pressure in middle ear so tympanic membrane moves and produces pain
- describe attenuation (tympanic) reflex
- there are 2 muscles in inner ear, the stapedius (innervated by CN VII) and tensor tympani (innervated by CN V). These muscles are activated during lound sounds to diminsh movement of middle ear bones to reduce damage to hair cells. Works best for loud sounds that last awhile instead of sudden loud sounds
- Auditory portion of inner ear
- Structure of cochlea
- v. boney spiral with 3 fluid filled spaces; the scala vestibuli, scala tympani, and the scala media. The scala vestibuli and tympani contain perilymph and the scala media contains endolymph with lots of potassium.
At the apex of the cochlea, the scala media ends and the scala vestibuli and scala tympani join through space called helicotrema
- how does cochlea transmit sound waves?
- stapes action on oval window converts mechanical displacement to hydraulic displacement. The movement of fluid displaces the basilar membrane and this causes neuronal AP
- in the cochlea, Since the noncompressible fluid is in a nonexpansible bone, where does fluid move?
- round window prevents the fluid from coming out of the cochlea
- Where do hi frequencies displace the basilar membrane of the cochlea?
- at the base
the base is stiff and narrow and sensitive to hi frequencies
- Where do lo frequencies displace the basilar membrane of the cochlea?
- At the Apex
the apex is floppy and wide and sensitive to low frequencies
- How are frequencies organized in basilar membrane of cochlea?
diff frequencies coded at different places along basilar membrane
- describe structure of Organ of Corti
- Attached to the basilar membrane are hair cells (receptor cells, not neurons) At the end of the hair cells, stereocilia attach the hair cells to the tectorial membrane which is on the edge of the cochlea. The stereocilia project into the endolymph of the scala media
- How are hair cells in organ of corti depolarized?
- remember that K+ conc in endolymph is hi and its lo in stereocilia. Tip links connects the stereocilia to the hair cells. When stereocilia move vertical toward tallest one there is enough stress on the tip links to keep K+ channels open so K+ moves into stereocilia causing DEPOLARIZATION. Ca+ also enters the cells so stereocilia can release the NT glutamate
- How are hair cells in organ of corti hyperpolarized?
- if stereocilia bend toward shortest stereocilia there is less tension on the tip lenghth and the K+ channels close and causes hyperpolarization
- Whats in spiral ganglion?
- spiral ganglion is in cochlea and it consists of bipolar cells and they synapse with the hair cells. this forms CN VIII
- What does characteristic freqnecy of a neuron depend on?
- hair cells that the neuron innervates (EX: if neuron innervates hair cells that is located tonotopically at the 8000 Hz level then neuron would be most sensitive to 8000Hz)
- How does in cochlea respond to a louder intensity?
- greater number of AP bc louder sound causes more movement of basilar membrane so more neurons will be activated
- What encodes frequnecy of sound? What encodes loudness of sound?
- frequency is encoded by which neurons are excited (location)
Loudness is coded by frequency of AP and number of neurons activated by sound
- Pathway of central auditory processing
- start at cochlea's spiral ganglion -> synapse bilaterally at the cochlear n. -> inferior colliculus via Lateral lemniscus -> medial geniculate n. _> primary auditory cortex
- what is primary nucleus where horizontal sound localizaion occus?
- Superior olivary n.
Can tell if sound comes from L or R
- How does Superor olivary n. tell if sound comes from L or R?
- there is a time delay with sound. Say sound comes from L side so sound will reach the L ear slightly earlier than the R ear so AP will be initiated earlier in L ear and move farther along axonal pathway than in R ear. Bc of arrangement of neurons in superior olivary n., there are neurons that discharge in response to delay between stimuli reaching ear, these are neurons that fire maximally when they get input from both ear simultaneously.
- What determines vertical sound localization?
- The pinna bc of its shape, sounds arriving from diffeent vertical levels vary so ear can sort out to determine amplitude of sound
- Where is primary auditory cortex?
- on superior temporal lobe. neurons here have tonotopic arrangement
- Where is secondary auditory cortex?
- surrounds primary auditory cortex. process input from primary auditory cortex and allows interpretation of sounds. This area is called Wernickes and is important for speech
- conductive hearing loss
- decrease conduction of sound from outer ear to inner ear
due to ear wax, perforation of tympanic membrane, otosclerosis
- sensorineural hearing loss
- due to loss of hair cells in inner ear
due to noise, drugs, tumors, presbycusis
- ringing in ears or perception without stimulus
caused by CNS problem or auditory problem
- treatments of hearing loss
- hearing aid-with intack auditory system but w/inadequate numbers of hair cell, hearing aids amplify incoming sounds
Cochlear implant: if hair cells are dead, a cochlear implant has electrodes that stimulate cochlear nerve
- structure and basic physiology of utricle and saccule
- both have a sensory apparatus called a macula where the hair cells are . the hair cells contain one long cirlium with a bulbous end called a kinocilium with many stereocilia. All cilia project into a gelatinous substance wich contains Calcium carbonate. Head movement cause the crystals to move due to gravity and this moves cilia changing NT release from hair cells
- What do otolith organs (saccule and utricle detect)
- linear acceleration and displacement of the head
- How does utricle and saccule work?
- when head moves change in gravity of head so crystals move in gelatinous substance bending the cilia. movement of cilia toward kinocilium depolarizes and movement away from kinocilium hyperpolarizes
the macula in the utricle is arranged horizontally, the macula in the saccule is arranged vertically so that no matter which way the head moves you are depolarzing and hyperpolarizing something
- anatomy of semicircular canals
- 3 of em oriented 90 degrees to one another
fluid in tube is endolymph
each canal has a buldge called an ampulla. There are hair cells within the ampulla. The cilia of the hair cells contian one kinocilium along with shorter stereocilia. The cilia project into gelatinous mass called the cupola that extends across the ampula. when the head moves the endolymph pushes on the cupola which then bends the cilia
- What does semicircular canals detect?
- angular acceleration, rotation of head
- Function of semicircular canals
- say the head rotates to the left, the inertia of the endolymph in the horizontal semicircular canal prevents it from following the rotation so it exerts a force in the directioni of the opposite rotatation of the inertia. the force of the endolymph is exerted against the cupola and this bends the cilia
- give pathway of how the central vestibulra pathways influence eye movements
- info leaves the semicircular canal through the vestibulocochlear n. (CN VIII) which goes and terminates in the vestibular nuclei in the medualla/pons
the vestibular n. connects to CN III,IV,and VI to coordinate eye movements
- What innervates Lateral rectus? medial Rectus?
- Lateral rectus innervated by CN VI
Medial recturs innnervated by CN III
- what eye muscles are activated and inhibited when you look to the right?
- R Lateral Rectus and L medial Rectus are activated
R medial rectus and L lateral rectus are inhibibed
- congjugate eye movements
- eyes move together
- Saccadees eye movement
- fast movement of the eye from one fixation point to another
- Smooth pursuit eye movements
- slow movements that track a target across a visual field
- fix eyes on obj but rotate head slowly, your eyes will try to maintain fixation of the object by a slow pursuit movement, eyes then move rapidly back to central position. the combination of both smooth pursuit movement and saccadic movemnt is nystagmus. The direction of nsystagmus depends upon the rapid movement
- describe vestibuloocular reflex
- reflex that maintains visual image on retina during head turning.
Ex: say head turns left, eyes must move to right to maintin image
so it will excite the L vestibular n. which will activate the R lateral rectus and the L medial rectus
- lowest level of motor system hierarchy
- alpha motor neurons that innervate skeletal m.
- middle level of motor system hierarchy
- brain regions that influence lowest level
includes sensorimotor cortex (corticospinal tract) BS, cerebellum, and basal ganglia
function is to execute movement of commandds intended by highest level. coordinate posture
- Highest level of motor system of hierarchy
- Brain regions that initiate desire to move
includes premotor and motor cortices and association areas of cortex and the limbic system
notifies lowere levels of the desired movements
- what is involved in large m. movements and makes sure the right muscle is contracted and inhibited?
- basal ganglia
- 2 major influences on alpha motor neuron
- 1. Brainstem (posture)
2. corticospinal system
- motorneuron pool
- all the motorneurons that inneravate a muscle
- Motor unit
- motorneuron and ALL its muscle fibers
- 2 ways to increase contraction of muscle by alpha motor neuron
- 1. increase frequency of AP in alpha motor neurons which will produce temporal faciliationa
2. recruitment of motor neurons is the most important way to increase force
- Shoud muscles that perform small movements have more or less muscles per motor units?
- should have few muscle fibers per motor neuron for example eye or finger
- what is recruited first smaller or larger motorneurons?
- smaller motorneurons are recruited first then larger ones.
example when you walk, smaller motorneurons, when you run start recruiting bigger motorneurons
size the motorneuron is proportional to AP size
- what is the difference between large and small motorneurons
- small motorneurons have less power but are more fatigue resistant
Large motor neurons have alot of power for a short amount of time bc they faigue quickly
- 2 major organs in muscle
- 1. muscle spindle which is sensitive to muscle length
2. golgi tendon which is sensitive to force and tension
- describe muscle spindles
- it is within the body of muscle and its encapsulated. It consists os specialized muscle fibers (intrafusal fibers) that signal the length of the muscle and the rate of change of length of the muscle.
The intrafusal fibers are innervated by Ia and II fibers that transmit lenght info to CNS
the ends of the intrafusal fibers are innervated by gamma motorneurons
- What info does muscle spindles give to CNS?
- muscle length. Example if muscle gets longer, sensory nerve endings stretch and there is an increase in AP of Ia and II fibers which tells the CNS how long the m. is
- sensory neuron that always comes from the muscle spindle only
- Ia fibers
- what is the firing of Ia fibers proportional to?
- length of muscle bc they are parallel to one another
- function of gamma motor neurons
- they innervate ends of muscle spindle. when it gets excited sends AP to ends of spindle and interfusal m. contracts. If you excite gamma motor neuron, it contract ends of spindle (pull each end of spindle) making the middle of the spindle longer which will increase the AP of the Ia fiber
gamma MN change the gain/sensitivity of the spindle bc spindles are only sensitive over a v. short range of movement. so now spindle sensitivity will change over entire range of movement
- what does golgie tendon do?
- senses tension of muscle.
golgi tendon has Ib fibers that generates AP proportional to AMOUNT OF TENSION (not length)
pull on muscle-tenses so AP caused by golgi tendon but contract m. LOTS more TENSION so more AP released by contracted muscle
- only reflex with just one synapse in pathway
- strethc reflex
- stretch reflex pathway
- muscle lengthens->spindle strectch->activates Ia fibers -> excite alpha motor neurson -> contract muscle
- how is a strech reflex performed?
- stretch reflex is initiated by tapping on a tendon, it activates the spindle which excites Ia fibers which excite alpha motor neurons which cause contraction of muscle
the other component of the stretch reflex comes from the muscle on the other side of the bone. interneurons inhibit the antagonistic m.
- what is the stretch reflex important for every day?
- to maintain posture
- tendon reflex pathway
- muscle tension increases -> golgi tendon Ib rease AP-> excite inhibitory neurons -> inhibit alpha motorneurons so muscle relaxes
- Describe how tendon reflex works?
- initiated by golgi tendon
if increase tension in muscle, Ib fibers are activated and they inhibit muscles by autogenic inhibition
the antagonist muscles are excited via interneurons
- describe withdrawl reflex and the crossed extensor refex and how they work together
- activation of pain fibers leads to flexion which causes withdrawl from the stimulus. so pain fibers basically excite flexors and inhibit extensors to permit withdrawl response
The crossed extensor reflex happens on the opposite side of the withdrawl (flexor) reflex. the crossed extensor reflex activates extensors and inhibit flexors to support you during withdrawl
- 2 types of movement disorders of the Basal ganglia
- 1. hypokinetic
- hypokinetic disorders
- reduced movements
get akinesia, bradykinesia
reduction in thalamocortical projection activity
- Parkinsons Disease
- type of hypokinetic disorder
loss of dopamine in Substania
treat with L Dopa
- hyperkinetic Disorders
- dyskinesias (increase movement)
thalamocortical projection is enhanced
- huntingtons disease
- loss of caudate and putamen
To tread decrease dopamine
- loss of subthalamic nuclei
reduces inhibion on thalmus to thalmocortical projection increases
- index of cortex's EPSPs and IPSPs
- Beta waves
- Delta waves
- deep sleep
- EEG during awake state
- beta and alpha waves
- REM EEG
- looks like awake beta and alpha waves
- purpose of histamine
- keeps you awake
- GABA function in sleep cycle
- inhibits histamine so you get sleepy
- Orexin function in sleep cycle
- allows you to stay awake all day and sleep all night
- During awake state what is hi and what is lo?
and orexin are hi but GABA is lo
- Durin non REM sleep, what is hi, what is lo/
- GABA is hi
and orexin are lo
- During REM sleep, what is hi, what is lo?
- norepi, serotonin are lo
ACH and GABA are hi this causes dreaming and REM sleep
- What is major circadian pacemaker?
- suprachiamatic nucleaus
does light/dark cycle by retinohypothalmic pathway
- What age group has highest REM sleep and goes into deeper sleep?
- how long does sleep cycle last
- 90 min
- when does deepes stages of sleep occur?
- in early evening in the first or second cycle
- What factor is very important for the sleep drive?
- adenosine accumulates through day and it excites GABA in the VLPO making you feel sleepy
- connection between sleep and immunie funciton
- when you are fighting infection, you sleep more
muramyl peptides from bacteria, GHRF, prostaglandin, IL 1 all cause sleep
- irresistible sleep attacks during the day.
pt enters REM wo other stages
due to loss of oxexin
- loss of muscle tone
- Sleep paralysis
- pt becomes paralyzed when drift in or out of sleep
- hypnogogic hallucinations
- graphic dreams that occur at sleep onset
- dysfunction of sleep
- sleep walking but does NOt occur during REM occurs at stage 3 or 4 of sleep
- REM behavior disorder
- paralysis of REM does NOT occur so you can act out dreams
- primary motivations
- allow species to survive
the four fs
3.farenhiet (temp regulation)
- Secondary motivations
- choices you make for primary motivations
most of humans behavior
- 2 components of emotion
- inner emotion
outer emotion-expression of emotion
you can supress the outer expression by you cant supress the inner emotion
- what reguates motivations and emotions?
- limbic system
- papex circuit
- core of limbic system
cingulate cortex (primary sensory cortex)
-> hippocampus ->mammilary body ->ant.nucleus of thalmus
- hippocampus primary role
- Kluver bucy syndrome
- bilateral destuction of temporal lobe
1. visual agnosia
2. oral tendencies
3. increase seeking behavior
5. loss of fear (docile)
6. increased vocal activity
- role of amygdala
- fear response
involved in rage and aggresion
attaches emotional significance to events
- function of prefrontal cortex and anterior cingulate cortex
- cortical areas responsible for experiencing emotion
- Primary function of hypothalmus
- emotional expression
it connects autonomic and somatic groups to mediate emotional responses
- function of ventral striatum
- helps select the appropriate behavior for a situation
- primary thalmic n. associated with the limbic system
- mediodorsal thalamic n.
- four major reward centers
- 1.dorsal pons
2.ventral tegmental area
interconnected by medial forebrain bundle
- common NT of reward centers
most important NT related to mood
- describe unique case of phineus gage
- pole through frontal cortex
found that frontal lobes are involved in expression and experience of emotion
- disorder of limbic
treat w/ drugs that block reuptake of norepi,dopamine,or serotonin
- disorder of limbic/mood
depression and mania
- too much dopamine
so must decreae dopamine to treat
- primary sensory cortices
- areas reciving sensory input from thalmus
- Primary motor cortex
- area producing final motor ouput
- unimodal sensory association cortex
- association cortex that integrates info related to a single sense
- Unimodal motor association
- premotor and supplementary motor regions
- Multimodal association cortex
- integrates multiple sense
analyzes sensory and motor output
- 3 types of multimodal association cortices
- 1. Posterior association area-integrates info from several sensory modalities
2.Anterior association area- prefrontal cortex. Allows thinking and planning
3. Limbic-gives emotional content to sensory info
- general flow of info from sensory input to motor output
- sensory receptors->primary sensory cortex->Unimodal sensory association cortex-> Posterior and limbic association areas-> Anterior association areas-> Unimodal motor association area-> Primary motor cortex -> Skeletal m. movement
- Function of L and R hemisphere reguarding language
- L side control speech
R side control non verbal and prosody
- language disorder due to brain damage
- Lesion of Broca
- Motor aphasia
problem with generating words but the person can understand the language so the person is aware they have a problem
- Lesion of Wernicke
- Sensory aphasia
pt cant understand words and has trouble making sense but does not know they have a problem
- Conduction aphasia
- problem with arcuate fasciculus
pt is fluent and can comprehend speech but they cant repeat words
- explicit (declarative memory
- memories for facts and events
to recall it you have to consciousessly think about it
- episodic memory
- recollection of a persons experieces. Memory of events
- Sementic memory
- knowledge. memory of facts
- implicit (nondeclarative) memory
- recalled memories unconcsiously
- procedural memory
- type of implicit memory
knowledge of how to do thing
- Previous exposure of something allow you to recall it faster
- Nonassociative memory
- person learns aspects of a single stimulus. The process is automatic
- person is used to stimulus its learned to be unimportant
- Response to stimulus gets larger with each repition
- Associative memory
- Requires a relationship between stimuli
- operant conditioning
- positive or negative reinforcement alters response
- What type of memory does the cerebellum store?
- implicity memory associated with muscles
ex:vestibuloocular reflex and the conditined eyeblink
- whay type of memory does the neostriatus store?
- procedural memory
- Where are explicit memories stored?
- multimodal association cortex
- How is memory stored/
- sensory input comes in medial temporal lobe
the amygdala attaches emotion to sensory input
the hippocampus distributes the memory to the proper regions of cortex
- Anterograde Amnesia
- inability to learn new info
- Retrograde amnesia
- inability to retrieve info
- Lesion in medial temporal lobe
- aterograde amnesia but you can recall previous memories
You must Login or Register to add cards