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54 Cards in this Set
- Front
- Back
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43 AD-scribonius largus
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electric torpedo ray to treat headache/gout
peripheral nerves |
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1755 AD- Le Roy
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wires around blind man head
-results= pain & flashes of light!! |
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1804 AD- Aldini
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-building on galvani animal electricity
-put electricity on parietal bone of person suffering melancholia (depression type) =improved mood |
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1960's applied electricity to animal brain!
weak___currents to cortex= current weaker than needed for causing showed that problem |
-DC, spont activity and evoked resonses for hours in rat
-AP's -sub threshold current can change neural excitability -brain under scalp/skull= high electrical resistance |
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faradays electromagnetic induction
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pass current thru coil=current in opposite direction of second coil and generate magnetic field when vary the EF
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magnetic fields good because (2)
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pass thru almost unaltered thru scalp/skull
minimally invasive stimulation |
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1896 d arsonval
1910 thompson show get ___if stimulate with coil |
phosphenes
based on stimulating retina also possible to stimulate thru visual cortex |
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TMS by
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Barker in 1985
76: focused peripheral nerve stimulators 82: improved design 85:tms |
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principles of tms (6)
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-current in coil
-magnetic field pulse change of magnetic field rat induce electric field induce tissue current induce charge density |
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electocompulsive therapy
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not same as tms
used for depression very effective BUT very invasive *tms may be able to do same thing but would be better not there yet |
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is tms non invasive
it excites__neurons is low or high tech 2 effects overtly measured |
yes
cortical low muscle twitches& if stimulate visual system to see flashes light (non random position of coil will affect where see flashes) |
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what affects tms stimulation efficiency
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-hardware ( risetime, intensity, coil shape and size)
-neural anatomy (orientation/length/beding angle, distance from coil, resistance, brain size) |
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tms
spatial resolution= temporal= good at/pros |
.5cm
50ms modulating brain activity minimally invasive **if it disrupts task performance then disrupted area is essential to (not just correlated) to task performance |
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cons of tms
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-not useful without priori info (need to know where we're going to stimulate with tms, ie any type of mapping needs other techniques mostly fMRI &/or ERP
-only stimulate surface structures -safety concerns |
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can you stimulate deeper with tms
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yes but affect/stimulate other ares along the way
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why use mri instead of tms
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see structural lesions/damage
discover areas involved in cognitive processes study role of any brain structure map structural connections |
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why use tms instead mri
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-if area is crucially involved
-better at mapping functional connectivity -induce plasticity -measure intracortical inhibition/facilitation |
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discuss flowchart of how its used/applied
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-intervention/modulating: rTMS (therapeutic or basic research) or time course single pulse
-monitoring: use single or paired pulse |
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single pulse tms good to use on people after rehab training after stroke because
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it porbes corticomotor pathway
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describe single pulse tms and corticomotor probing
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-pulse over primary motor cortex
-attach electrode to hand-->measure muscle activity creates Motor Evoked Potential from CONTRALATERAL hand -look at MEP's latency&luitude (2 good diagnostic tools for stroke/multiple sclerosis |
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TMS intensity for motor/visual target
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-use motor threshold
find stimulation--> twitch look at amp's in emg take the middle value *visible? subjective? EMG? -use visual threshold (flashes of light) |
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TMS intensity for NOT motor/visual target
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relative threshold approach
ex) MT (motor threshold) 61% so lets go above it like 80% and see what happens |
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w/ TMS how do you know where you're stimulating
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-with muscle its easy, stimulate areas until one spot gives best muscle response
-if not muscle, use other techniques ex) BRAINSIGHT --> functional mri, can use as overlay w/ tms |
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after pulse happens have 2 main effects
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-sync neurons activity
-sync--> gaba IPSP's (this also helped us learned about gaba function) lasts 50-250ms |
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TMS=cortical
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inhibition
-pulse pinches muscle= MEP (spike you see) then have silent/dead period= cortical silent period |
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cortical silent period is____in stroke patients and can inhibit many other functions
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prolonged
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next slides discuss paired pulse
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paired pulse
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-little tiny pulse doesnt cause effect itself BUT effects brain--> tiny pulse if given for ex) 1ms before high intensity pulse the MEP of high intensity GONE!!!
-around 6-8 the MEP of high pulse comes back -little pulse influencing brain response to high pulse -as interval time increase MEP of second pulse increases * at 10-15 ms see facilitation |
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w/ paired pulse learned that
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-gaba chemical promote the inhibitory aspects
-glutamate promotes the facilitation ie) can indirectly measure ratio of inhibitory and excitatory neurochemicals in brain |
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sICI
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short-interval intracortical inhibition
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sICI and silent period measures of _____and operate thru____mechanisms
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inhibition
different **sICI uses gaba A-R **silent period uses gaba B-R |
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lisa koski looking at multiple sclerosis (MS) and sICI cSP whats one thing she found
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-those with increased inhibition were performing better on some tasks
-maybe due to adjustment in NT levels/excitability that determines how the damage will be manifested by disabilties |
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tms safety concerns
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-cant do on
pregnant metal in head history of seizure taking TCA/ drugs change neural excitabilty pacemaker -can give you headache (main complaint, more do to constraint on head/sitting there for long time) hearing loss (inconsistent data, just give earplugs) |
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look at intervention: time course single pulse
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used by amassian
showed suppresion of______by tms stimulation of |
visual percpetion
occipital cortex *this study showed TMS as mapping tool |
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describe amassian study
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-flash letters and ask you to say ones you saw
-at intervals combined tms single pulse with flashing letter -smaller the interval the less likely to see certain letters, show time interval that optimal for info to properly reach area/process info -also could promote seeing some letters better like the letter farthest right *reminder: stimulation lead to inhibition of visual perception |
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rTMS
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-repetitive tms
-varying freq of pulses -longer lasting effects!! -summation of neurophysiological effects |
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rTMS:
2 type of study design |
online= stimulation SAME time as task performed
**all online is excitatory offline= stimulation then perform task **1 Hz vs 10Hz applies only to offline |
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1Hz vs 10Hz
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1Hz: suppresses neural excitability
10 Hz: enhances neural excitability |
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safety issues with rTMS;
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similar to single/simple tms
increased chance of seizure risk defined by intensity, freq, number trains international workshop on safety of rTMS= define safety parameters |
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phineas gage example of__lesion
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real
damage to ant frontal lobe |
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virtual lesions
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temporary
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use virtual lesion to study
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area MT--> visual motion perception
PFC--> hand selection in rxn time SMA--> performance of over learned sequential finger movement temporal cortex--> free recall of verbal material *SKY IS THE LIMIT THEORETICALLY (at least at surface) |
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wada test
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-inject sodium amobarbital into internal carotid artery
-ask patient name images -determines laterality function |
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can rTMS be used for wada
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potential there, some shown
-rTMS over brocas area (high intensity/freq) showed similar results to wada |
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first tms lab in canada by
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paus
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Paus:
describe experiment looking at rTMS & PET |
-10 Hz rTMS over right frontal eye field
-5 pulses/train -# trains, 5, 10, 15, 20,25, 30 -brain regions show inc/dec in uptake/metabolism based on # trains -some regions connected to areas that were stimulated also became stimulated **first ever demonstration of effective connectivity without behavioral confound |
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rTMS as therapeutic used on stroke patients discuss study
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-10 Hz on lesions/damaged hemi= increased excitability (not as high as unlesioned)
-also gave 1Hz on unlesioned/normal hemi= decrease in excitabilty of unlesioned hemi BUT increased excitability on lesioned hemi ie) maybe the unlesioned excitabilty has dampening effect on lesioned |
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rTMS in humans vs animals
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-humans
high freq= LTP low freq=LTD -animals LTP/LTD needs longer stimulation/higher frew therefore use THETA burst pulse |
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TBS
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-intermittent or use continuous
-much faster procedure -3 50Hz pulses repeated every 200ms given either: intermittent or continuous |
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would we get better results with theta burst pulse if used in humans
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-for inhibitory
cTBS effect last longer than rTMS BUT effect same size -for facilitation no difference between iTBS and rTMS |
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non fluent aphasia:
lesion that include__area result from identified by |
brocas ;middle cerebral artery infarts
agrammatism in speech/writing |
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giving rTMS to non fluent aphasics=
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long term benefits
supports idea that increased contralateral activity not compensatory potential therapeutic option |
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rTMS also possible therapy for
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depression
symtoms on Ham D scale decrease with rTMS |
