Neuro mod 2 Flashcards
Process of Brain organization and specialization
brain development
processes in prenatal brain development (there are 5, list in order)
- cell division (mitosis)
- cell migration
- cell differentiation
- cell connections (synaptogenesis: connecting with other cells)
- cell death (apoptosis)
most development is shaped by?
environment
brain + skin
ectoderm
central stuff in body
endoderm
proliferation of neurons
neurogenesis
when does neurogenesis begin
42 days post conception
neurogenesis ends
20 weeks
where do cells proliferate
ventricular zone
in the ventricular zone cells migrate using what
radial glia and intercellular signaling
birth date of cells matters for (2 words)?
final location
cell type is dependent on
what a gene cell expresses
cell-autonomous –> genes in cell direct expression
intrinsic factors
signaling molecules from other cells
Inducing factors
substance causing differentiation
Inducer
substance that can cause cells to differentiate into different types based on its concentration
Morphogen
in CNS most neuronal differentiation is based on
local cell-cell interaction
central core
growth cone
Have cues to tell to stop, go, or turn (repulsive or attractive cues
Filopodia
uses structural support to guide growth
pioneer axons
o Released from post synaptic to pre-synaptic cell
o Prevent apoptosis –> survival of presynaptic neuron
o Lack of neurotrophic factors –> cell death
Neurotrophic factors
o “falling leaves”
o Natural cell death
Blebbing
Cell shrinkage
Condensation of chromatin
Phagocytosis of cellular remains
o Many pathways to the of apoptosis, but all have something to do with
Mitochondria
Ca2+ concentration
o Each pro-apoptotic factors works in a different wat, but generally activate caspases
o Cascade if events destroy proteins and AND and cell can’t survive
o Too much calcium breaking up of mitochondria
o Protective factors
o Bcl-2 protein family
Apoptosis
blind if deprived during sensitive period
binocular deprivation
deprived eye will not respond
monocular deprivation
Neurons that fire together, wire together
Hebbian synapse
process of receiving stimulus energies from external environment and transferring them into neural energy
sensation
organizing + interpreting info
perception
sense stimulus
sensory receptor organs
point at which an individual detects a 50% of time
absolute threshold
receptor cells convert energy into electrical signals
sensory transduction
-rules by which action potentials in a sensory system reflect a physical stimulus
–frequency of action potentials
–pattern of action potentials
–# of neurons
–identity of neurons firing
coding
less hyper polarized = ?
less signaling needed
many receptors become less and less responsive as stimulus is maintained
adaptation
go through phases and becomes less responsive
phasic receptors
stable receptors
tonic receptors
accessory structure can reduce the level of input we get through sensory receptor
controlling sensory processing
attend to one thing instead of all things
top=down processing
skin is a type of what
sensory organ
info is transduced by ___ in skin + muscles innervated by DORSAL ROOT and GANGLION NEURONS
mechanoreceptors
receptor involved in touch, vibration, and pressure
*respond to stretch so Na can come in
mechanoreceptors
Tactile sensitivity is greatest on __ skin
glabrous (hairless)
palms + sole of feet + lips + fingertips
glabrous (hairless skin)
at boundary of epidermis and dermis
Type 1
deep within dermis
type 2
cease firing in response to constant amplification
*active when velocity stimulation changes
rapid adapting neurons
firing rate proportional to skin indentation
steady pressure
response to sensory stimuli
-how quickly does a cell stop responding to a stimulus
temporal dynamics
-high threshold
-initial spiking proportional to speed skin is indented and total amount of pressure
-info about spatial attributes
slow-adapting
region of skin in which a stimulus will modify firing of action potential
affected by:
-branches characteristics of afferent with in skin
-density of affect fibers supplying
receptive fields
-cells detect change over wide area
-less precise perception
large receptive fields
-cells detect change over small area
-more precise perception
small receptive fields
minimum intensity of stimulation required to generate an AP
sensory threshold
lower threshold for responding goals and detect charge
fast adapting neurons
-10-15%
-deep in hypodermic
-receptive fields –> large + ambiguous
-look like onions (small)
*detect vibrations transmitted through objects being grasped
*functional displacement of skin when hand moves across object
-adapting propertiesL fast-adapting
-sensory threshold: low response threshold
-receptive field: large + ambiguous
Pacinian afferent
-dense innervation of skin
-tips of dermal papillae adjacent to primary ridges *closest to skin surface
-globular fluid filled structure
-encloses flattened epithelial cells with nerve terminal entwined in layers
-Receptive fields: relatively small
-Adaptation properties: fast adapting
-sensory threshold: decrease response threshold
*sensitive to abrupt changes in shapes of objects (edges + corners)
-Texture: fluttering, stroking
Meisser corpuscle afferent
-not encapsulated + no layers
*especially dense in fingertips
-only afferent to sample info from receptor cells
-located in epidermis
-detects changes in steady pressure good for curvature/form of objects
-detects texture (holding bball)
-slow adapting (high threshold)
*highest spatial resolution (0.5mm)
Merkel cell afferent
-elongated spindle shape
-deep in dermis; ligaments and tendons
-respond to internally generated stimuli
-stretch of skin
-large and vague receptive field
-slow adapting (high threshold)
Ruffini cell afferent
auditory processing sensory organ
ear (cochlea)
auditory processing sensory receptors
inner hair cells (IHS)
adequate stimuli stimuli
sound (pressure waves)
-pressure waves
-increase when waves are densely packed
longitudinal waves
How sounds differ
-pitch (high vs low): frequency
-loudness: amplitude
-Timbre: quality of sound – complexity
-wave length (how many cycles pass a given pt in a sec)
-measured in Hz
frequency
increasing frequency = ?
increase pitch, increase waves + decrease wavelength
decreasing frequency = ?
decrease pitch, decrease waves, increase length
“height” (intensity) of sound wave
-measured in decibels
-increase amplitude, more molecules in crest
-0 db = weakest sound ear can detect
-120 db = max
-1 dB just noticeable difference
amplitude
sounds with numerous frequencies of sound blended together
complexity sound
amplifies sound + boost frequencies
Pinna
end is ear drum
- 1.5 in long
ear canal
aka ear drum
-flexible + vibrates
-end of ear canal
-attaches to malleus
tympanic membrane
smallest bones in body
-malleus, incus, stapes
ossicles
-stapes push on oval window
-connecting to inner ear
middle –> inner ear
sound converted into neural activity in cochlea
*filled with non compressible fluid
inner ear
attach to oval window
scala vestibuli
contains basilar membrane that sits under organ of corti
scala media
attaches to round window
scala tympani
*affects pitch
-thickness + width vary
-properties affect mechanical properties of membrane
-lies under organ of corti (has IHCS)
*different frequencies cause max displacement at different points on ___
basilar membrane
3 rows of __
OHC (outer hair cells)
1 row of ___
IHC
basilar membrane driven upwards –> shearing motion btw tectorial membrane + organ of court –> bending of sterocilia –> ___
excitation
___ sterocilia extend into bottom of tectorial membrane
IHC
basilar membrane moves downwards –> opposite –> bending of sterocilia in opposite direction –> ___
inhibition
-bending of stereo cilia –> ___ opening
tip links
all levels of auditory pathways are spatially arranged according to auditory frequencies to which they respond
tonotopic organization
where does synapse happen at inferior colliculus
midbrain
where does synapse happen at medial geniculate
thalamus
where does synapse happen in auditory cortex
temporal lobe
min. discriminable frequency difference
2 hz
area of basilar membrane that vibrates determines perceived pitch
place theory
rate of neuronal firing is directly related to frequency
- not 1:1 correspondence for increase frequencies
temporal theory
multiple hair cells respond to __ frequencies + amplitude
increase
-“loudness”
-IHC= most sensitive to a particular frequencies but resounds to similar frequencies
-tuning curves –> more intense stimulus –> increase IHCs respond
encoding amplitude
when you age, there is a __ in sensitivity go IHCs
decrease
lack of functional IHCs cochlear hair cells
-auditory nerve cells not excitable in typical manner
-gives affecting hair cell structure + function
sensorineural deafness
electrically stimulates cochlea + auditory nerve fibers
cochlear implant
-signaling btw brain + muscles
-be able to receive sensory feedback from muscles , tendons, + joints to monitor movement
made of muscle fibers
- diameter of 50–100 mm
-length 2-6 cm
-muscles contain millions of muscle fibers
–> made of myofibrils
–> contains thick (myosin) and thin (actin) filaments
skeletal muscle
-helps control spinal cord + brain muscles
-final common pathway: info processing pathway consisting of ALL motor neurons in body
motor neuron
motor neurons meet muscle fibers at ____
neuromuscular junction (NMJ)
single motor neuron + all the muscle fibers it innervates via axonal branches
motor unit
number of muscle fibers innervated by motor neurons
innervation ratio
muscles involved in fine movement ___ innervation ratio
decrease
gross movements ___ innervation ratio
increase
- ACH released from motor neuron at endplate of muscle fiber – ACH binds to receptors depolarizing the end plate causing action potential
- action potential travels across membrane of muscle fiber
- depolarization cases ca2+ being released from sarcoplasmic reticulum
- ca2+ binds to sites on thin filaments –> conformational change
– myosin head binds to thin filament actin and overalls btw thick and thin filaments increasing shortening of fiber –> muscle contractions - acetylcholinesterase breaks down ACH at NMJ –> no more AP –> membrane returning to normal
- ca2+ actively transported back to sarcoplasmic reticulum
- conformational change in thin filament –> myosin head can’t stay attached –> overlap btw thick and thin filament decreases
presynaptic synapse on muscle fiber
info about position and movement of the body that is sent to the brain
-body sense
different types: muscle spindles and Golgi tendon organ
proprioceptive feedback
*only lengthening and shortening
-send AP to CNS in response to lengthening of muscle and velocity of muscle stretch
- muscle stretches
- stretch causes deformation of spindle at sensory ending
- deformation –> A.P in afferent fibers that inform CNS of stretch and triggers changes in motor neurons
muscle spindles
deals with velocity of muscles
primary sensory ending
deals with how much we are lengthening the muscles
secondary sensory ending
simple, highly stereotyped + unlearned respond to stimulus
reflex
-doesn’t involve brain, only spinal cord + cells in PNS
stretch reflex
responds to stretch + contraction
-provides feedback about force of muscle contractions
-extend arm – little to no rxn
-lift something heavy – reaction
golgi tendon
-primary motor cortex
-supplemental motor area
-premotor cortex
cortical motor
-executive region for movement initiation
-contralateral control
-more M1 devoted to body parts involved in elaborate movements
*actually having movement happen
*more neurons code direction of movements
primary motor cortex (M1)
communicate to M1 + non cortical motor regions
*MOVEMENT PLANNING
premotor + supplementary motor areas
with strong initiation movement initiated –> more complex movement than m1
premotor cortex
movement based on internal cues “stretching”
-strong stimulation –> bilateral movements –> coordinate movement on both sides
supplemental motor area
for change in PNS, cortical neurons project to motor neurons in spinal cord via ____
cortical spinal tract
basal ganglia + cerebellum
subcortical region
set of nuclei important of restarting and ending movement
-modulates activity in cortical motor regions –> loss of communications with m1 * important for acquired skills
basal ganglia
important for monitoring ongoing movements
-modulates activity in cortical motor region –> lots of communication with SMA
-works with inhibition
cerebellum
project to motor neurons in spinal cord via extrapyramidal system (brainstem)
-communicates with cortical areas via thalamus
messages sent form subcortical regions
