Flashcards in Neuro3Jordan Deck (122):
What 4 things do we use to classify peripheral axons?
and what waves they use to contribute to an action potential
Thicker = faster
What type of fiber, sensory or motor, contains Aalpha, Agamma, B, and C?
What about Aalpha, Abeta, Adelta, and C?
Motor = AABC
Sensory = AAAC
What is a slowly adapting fiber?
Responds to prolonged and constant stimulation
Responds to beginning and end of a stimulus or intensification
What mechanoreceptor interprets fine, light touch and proprioception? Where are they located? What do they look like? Receptive field size?
- Meissner Corpuscles
- Glabrous (hairless) skin (Superficial)
- Large, myelinated fibers, adapt quickly.
- Receptive field is small
What mechanoreceptor interprets vibration and pressure? Where are they located? What do they look like? Receptive field?
- Deep skin, ligaments, joints. (Deep)
- Large, myelinated, quick adaptors
- Look like onions
- Large receptive fields
What mechanoreceptor does (visceral?) pain and temperature?
Pressure, deep static touch and proprioception?
Pressure, slippage of objects, and joint angles?
Free nerve endings
How does a pre-synaptic inhibition work?
Inhibitory neuron releases GABA --> Cl- influx --> hyperpolarization --> less Ca+ --> Less NT release
What are the functions of S1, S2 and PTO?
S1 - initial processing, position sense, size and shape discrimination
S2 - integration of many processes into larger schemes; comparison between objects and memory, cognitive touch
PTO - emotional responese; spatial coordinates of self, names objects.
Which Cortical processing unit can be altered, and how is this arranged?
S1 can be grown or diminished with practice. It is arranged in teh hounculus
Most (Primary sensory) cortex projections go to:
For the purpose of: ?
Thalamus via corticothalamic axons
What are cortico- cortical projections
links primary and association areas of sensory; processes multiple info at once
What are corticofugal projections?
Cortex --> thalamus, medulla, SC
inhibit and prevent sensory intensity
What is the structur eof a free nerve ending? What about the types?
Lack specialized capsules or cells
- Non peptidergic
Which type of nociceptor receptor is most cutaneous nerve endings?
What ions are allowed through on the TRP nocicpeotrs?
Ca, Na, K
What is a nociception channel that allows sodium through?
What are 3 other ligands that can act as noxious stimuli?
Histamin, bradykinin, SP & CGRP
What NTs are relased by C fibers and alpha delta fibers onto interneurons? What receptor do the interneurons hav?
Alpha delta fibers: EAA only
C fibers: EAA and SP, CGRP
The gate control theory is specific to what pain fibers?
and Ab, that excite the inhibitory post synaptic neuron
What is the mechanism of rubbing a painful spot to decrease stuff?
Ab fiber by normal stimuli --> Synapse on inhibitory interneuron --> EAA --> internuron release Glyicine --> Reduces sensation of pain.
What is the mechanism of descending inhibition?
PAG --> LC (NE) Raphe Nuclei (Serotonin) --> secondary inhibitory interneuron --> opiods --> Mu receptor on C fiber --> Reduce nociception
How can PAG be activated?
EAA, opiates, Cannabinoids
HOw does bradykinin influence chronic pain? (2)
Increase inflammation via vasodilation
Mediates NGF (nerve growth factor) --> production of BDNF, which is an NT that binds to TrkA
Nociception interpretation happens in what area of the brain? Damage of this causes what?
Asymbolia - pain without unpleasantness
What is afterdischarge?
Discharge of neural impulses after termination of initating simulation?
Monosynaptic or polysynaptic?
DTRs Stretch = mono
GTO = poly
Golgi tendon organ is used for what sensation? What fiber type?
Nuclear bag fiber?
Annulospiral, length and speed of length
length only, tension
Limb position, joint movements. I
What sensory fiber of the msucle spindle is the primary afferent fiber?
1a, from annulospiral fibers
When a muscle is contracted, the muscle spindle is loose. What tightens that back up? Why do we need to tighten it?
gamma motor neurons. Makes sensory portions sensitive again .
What is the reaction of muscle spindles in a UMN to cause spasticity? Rigidity?
The gamma motor neurons are constantly activated.
Rigidity: Alpha motor Neurons continuous activation (inhibitory cortical influences are messed up)
What causes decorticate lesioning? ANd what is the pt sxs?
Sx: Flexor position
Cause: Internal capsule stroke above superior colliculus. Severe brain damage.
What causes decerebrate lesioning? Sx?
Sx: Extensor position, (worse prognosis)
Cause: lesion below red nucleus, on postural centers.
Where are central pattern generator cells located?
In the Spinal Cord.
Where does the dorsal pathway go to?
Inferior temporal cortex
When reaching for an object, what isthe motor pathway in the cortex?
V1 --> Along dominant neurons (either visual or motor or both) --> AIP, PFG --> F5
We talk about columns all the time, but in different places they are differnet hings.
In the cortex the columns are organized:
Primary motor columns?
Cortex: They go through the entire 6 layers, but IV receives input and V/VI output.
Primary motor Cortex:
has one column with 2 types of neurons in it, one to start motion, one to maintain motion
- Excited by angles of light, and prefer one eye over the other
- Third spatial dimension adds depth to vision
Which of the 3 motor complexes can switch strategies in the middle of a movement? This itself has 2 separate divisions, wha tare they and their fxns?
Supplementary motor complex
SMA: Sets motor programs for learned sequences
pSMA: Learns the new complex sequences
What part of teh cerebellum ensures proper execution of coordinated movements and anticipates future body position in a feed forward manner? What if this is lesioned? What nuclei are used? What are the inputs?
Lesion: truncal ataxia
fastigial, globose, emboliform
Inputs: spinocerebellar tract, spinal trigeminal, visual and auditory systems
What part of the cerebelum sequences rapid movements and timing? Lesion? Inputs? Outputs?
Cerebro (ponto) cerebellum!
Input: cortex --> dentate nucleus via thalamus
Output: back to thalamus via premotor nucleus
What part of the cerebellum sequences balance and eye movements? Input? output? Lesion?
input: eyes and ears, vestibular nucleus
output: LMN in SC
balance and gait issues
What NTs do the cerebellum fibers use?
Name Walking or Arm/Hand:
CPG in spinal cord?
Sensory input is crucial?
Comes from Cerebellum, basal ganglia?
Derived from cortex?
The straitum is stimulated from what?
Substantia nigra w/ glutamate and motor corte. via glutamate
What happens if you lesion the substantia nigra pars compacta?
Parkinson tremors, slowness, rigidity
The Striatonigral path is from what to what with what NT?
Straitum to GPi or SNpr
A pt presents with Sx of huntington's disease. in order to Dx you can do a CT and look at what part of teh brain? What NT?
B/n the straitum parts, ACh.
What is the largest input to the striatum? Next?
From cortex with glutamate.
From substantia nigra with dopamine
Output: inhibitory Medium spiny neurons via GABA
Parkinsons' can be caused by lesions of what now? (3)
Subthalamic nucleus gets inputs from what?
outputs go to where?
inputs: frontal lobe & globus pallidius externus
Outputs: Excitatory via glutamate
Dopamine has 2 receptors. What are they and their fxns?
D1 - excitator the direct pathway
D2 - inhibitory. Inhibit the indirect pathway = more movement
IN parkinsons, which basal ganglia is continous?
Indirect pathway overactive, and direct cannot be stimulated.
In the taste pathway, serotonin binds to what? ATP?
Post and pre-gustatory
MOA for salty?
Epithelial salt channels (ENaC) → Na crosses into cells → depolarizes it → increases intracellular Ca → serotonin released
MOA for sour?
H+ ions → inhibit potassium channels → depolarization → increased intracellular Ca → serotonin release
MOA for sweet, umami, and bitter?
Binds to GPCR → PLC-IP3 pathway → IP3R3--> increase intracellular calcium → TRPM5 activation → sodium flows in→ depolarization → ATP release via Panx1 channels → neurotransmitter release
Bitter: high affinity
MOA for smell rceptors
Odorant binds Golf → adenylyl cyclase → ↑ cAMP → opens cyclic nucleotide gated channels CNGC → cation influx and depolarization
How does smell adaptation work?
CNGC loses sensitivity for cAMP
What ganglion are for what taste nerves? What is the pathway from these 3
VII - geniculate
IX - petrosal
X - nodose
Nucleus tractus solitarius/gustatory area --> VPM --> PLIC --> Gustatory complex (post central gyrus, frontal operculum, insular cortex)
What is the function of the orbitofrontal cortex?
Pathway of smell back to brain?
Olfactory neuron release→ glutamate → glomerulus → mitral, granule, periglomerular cells → olfactory tract → olfactory cortex → all over
Fxns of smell cells? Mitral, granule, periglomerular?
granule and perigromlerular = Gaba
Mitral - projects to olfactory
Components of Olfactory cortex?
- Anterior olfactory nucleus --> Relay to cortex
- Olfactory tubercle
- Piriform complex:
--> hypothalamus --> appetite and hunger
--> thalamus --> medial orbitofrontal cortex --> taste, sight, smell
- Anterior cortical amgydaloid --> emotion and fear
- Periamygdaloid --> emotional odor
- Lateral entorhinal --> hippocampus --> memory of eating
Neurons or taste cells?
- Stays open at rest with fixed permeability?
- Na+ gradient fluctuates?
- Voltage dependent?
- Sodium permeability can change?
A pt with migraines or psychotic states may experience what olfactory/gustatory symptom?
What acts on ciliary muscle to change shape of lens?
Parasympathetics make it more round
Sympathetics flatten it
What visual cells are vertical? Horizontal?
Vertical: rods/cones, bipolar, ganglion cells
Horizontal and amacrine
What is the difference between on center and off centers vesides where the depolarization is?
The depolar glutamate receptors are AMPA, where as the on center ones are GPCR Gi.
AMPA --> incease Na
What type of cell do Rods converge on?
ON CENTER bipolar --> amacrine --> cone bipolar --> ganglion
What is the purpose of horizontal cells?
to repress the ganglion to sharpen the image via GABA
What is the function of the lateral geniculate body?
Control motions of eyes to converge, control focus based on distance, map objects in space
There are a bunch of layers in the primary visual cortex. What are the fxns of each?
IV and V, VIis important
I-III - networking between V1 and other parts of cortex
IV - Input
V - VI - output to Lateral Geniculate body, thalamus, subcortical regions
VI - Edges and contours of objects
Name the Brodman area associated with this Visual area, and the fxn of the Visual area.
V1 - Brodman 17
- Primary visual cortex
V2 - Greater 18
- Depth perception
V3a = Lesser 18
- Identifies motion
V4 - 19
- Processes Color inputs
V5- 19 (Middle temporal)
S1- 3, 1, 2
- Primary Sensory Area
What end of hair cells is endolymph? Perilymph?
Endolymph: apical end
Perilymph: basal end.
Ah yes, sound waves. pathway?
*sound waves* → tympanic membrane → ossicles → oval window → Scala vestibuli pressure falls below scala tympani --> vibrates basement (basilar) membrane of cochlea→ tectorial membrane --> muscle called prestin moves the outer hair cells --> TRPA1 --> K+ influx --> depolar --> Ca --> glutamate to perilymph --> AP
Inner hair cells
Outer hair cells
Inner: primary source of auditory info
outer: Amplifier, Contractile, boosts vibrations
WHere do the afferent fibers come from to the hair cells?
Afferent - spiral ganglia
Efferent - superior olivary complex to outer
There is a ventral and dorsal cochlear nuclei. Difference in fxn?
Ventral - Nature of sound, high or low
Dorsal - lcoation of sound. localizes
There is a medial and lateral superior olivary nuclei, different fxns?
Medial SO - Interaural time difference via glutamate
lateral SO - intensity differences also help localize
Inferior colliculi fxn?
Suppresses echo information to spatially map sounds
What is the general pathway of sound wave data?
Cochlear nuclei --> Superior Olivary Nucleus --> Inferior colliculi --> Superior Colliculi --> Medial Geniculate
Difference between primary auditory complex and associated auditory cortical areas?
A1 - yes sound! volume, rate, loudness!
Association: Music and more complex stuff
What can protect the ear from loud noises?
OCN (olivocochlear nucleus)
Tensor tympani V and stapedius VII; prevents low frquency damage
What are otoacoustic emissions?
sensorineural hearing loss?
Otoacoustic: Ears producing sound via motile outer hair cells (hear loss testing)
Sensorineural: damage to hair fibers and nerve, usually OHC damage
Cerebellum has a big part in vestibular activities.
Describe what is stimulated when a person is:
Suppresses optic reflexes to allow for voluntary motion.
Spinning: Horizontal semicircular canals --> medial rectus activated, lateral rectus inhibited, oppo on other eye
Fall back: posterior semicircular canal --> superior oblique activated, inferior oblique inhibited
Falling forward --> anterior semicircular canal --> superior rectus and inferior rectus muscle inhibited.
WHat are 2 insular cortex fxns?
interpretation of pain
Each part of the Central Nervous System has reactions. Name these reflexes for where they lie (cortex, brainstem, spinal reflexes):
Where exactly are GTOs located on the muscle?
Where the muscle junctions with the tendon
What is lost in a spinal shock?
Sensation and reflexes under the lesion
There are 6 layers in the cortex. 2 of which are enlarged in the primary sensory cortex. Which ones and why?
III and IV
bc the axons from the thalamus terminate there.
Neuronal columns organized side by side?
Side by side are totally different, only same location on body
Up and down = same same
2 actions of serotonergic and noradrenergic neurons:
1. Acivate local interneurons to inhibit
2. Suppress spinothalamic projections
What is antidromic signaling?
The efferent actions of nociceptors - Smooth muscle contraction, arteriole dilation, mast cell degranulation
Also cause of referred pain
What makes up gustatory complex?
(post central gyrus, frontal operculum, insular cortex)
What 2 places can neurogenesis occur?
Olfactory and dentate gyrus of hippocampus
Which part of the cerebellum can sense future movements and make changes for that?
What is the function of basal ganglia?
PLanning and programming,
(Somehwere in initiaiton)
Difference between SNpr and SNpc?
SNpc receives inputs
- relays to striatum via nigrostriatal path (dopamine)
SNpr is the output
Out usually to inhibit thalamus (GABA)
Which basal ganglia receives most of the input?
Where does input come from?
How does it talk to other basal ganglia?
How does it talk to itself?
Cortex via glutamate
SNpc via dopamine
Output is inhibitory via medium spiny neurons GABA.
Self: intrastriatal: cholinergic, stimulatory
Which basal ganglia receives all the input from the frontal lobe?
How does it talk to other basal ganglia?
Excitatory via glutamate
corticostriatum what does it release?
What is released from nigrostriatal tract?
SN --> striatum dopamine
What is the effect of the loss of dopamine in Parkinson's pts? Where does this dopamine come from?
Comes from SNpc
The thalamus direct and indirect pathways.
If no Dopamine binding to D2 to inhibit the inhibitory pathway, then pt has trouble starting the movement.
If no dopamine binding to D1 to excite the direct pathway, also trouble starting movement. ( can still be stimulated by cortex via glutamate)
What is the path of light to the RPE?
Where does the retina send information to? (6)
Accessory optic nuclei
Of the targets that the retina sends information to, which is in charge ofthe:
- pupillary light reflex?
- Circadian Rhythms and light-dark entrainment?
- Advanced visual processsing?
- Controls accommodation, distance vision and positions of objects?
- Saccadic movement (simultaneous movement of both eyes)
Accessory optic nuclei
Lateral Geniculate body
What part of the brain allows you to recognize faces and name objects?
Ventral pathway, "What" from V1 to the inferior temporal cortex
Indirect pathway of basal ganglia, go!
Direct pathway, Go!
What happens in Parkinson's?
Striatum (GABA) --> GPe (GABA) --> STN (glutamate) --> Gi (GABA) -->Thalamus --> movement
Cortex (glutamate) --> Striatum (Gaba) SNpr & GPi (Gaba) --> Thalamus --> movement
Which semicircular canal activates the oblique eye muscles?
posterior semicircular canals
Anterior semicircular canal
Where do taste and olfactory first integrate?
Nucleus Tractus Solitarius
Cross talk between hypothalamus and cortex in the gustatory
Interpret hunger and appetite
A sign change is used on what receptor?
Difference between the PTO and the medial orbitofrontal complex?
PTO --> Cortical processing, somatosensory, hearing, vision
MOF --> Integration of visual, somatosensory, olfactory, gustatory
Where is the Cl- influx tract located?
What autonomic receptors have the same function and intracellular stuff?
HAV1 M&M --> Smooth muscle contraction via Phospholipase C
MAD 2s --> Gi (adenylyl cyclase)
What releases glycine in what pathway?
Gate control theory, the inhibitory interneuron releases glycine after being stimulated by the Ab with glutamate
What FIBERS recept heat? Cold?
Heat: C fibers
Cold: C fiber sand alpha delta
In a Parkinson's pt, what are the concentrations of:
Ach is increased
GABA is decreased
Dopamine is decreased.
TRPM5 is found where?
SUB taste pathways
Hair cells are rich in what protein?
Depolarization in a hair cell stimulates 2 paths.
Fxn of superior colliculus?
Vertical height to sound
Fxn of medial geniculate body?
Processes speech inflections
Which olivocochlear efferent innervates what hair cells?
Medial = outer
Lateral = inner