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TMS - LECTURE 9-10
Fichas del conjunto (10)
- 1What are the limitations of studying case studies for lesions effectsArea of lesions can't be chosen, one must wait for the lesion to occur, the brain might compensate for the lesioned area therefore the researcher is studying an abnormal brain
- 2What is TMSTMS is a technique which uses a rapidly changing magnetic field to induce electrical current in the brain to lesion a part of the brain temporarily
the currrent is 1ms STRONG 2 TESla magnetic filed
field is created by charging the capactior and then suddenly disabling it. - 3what are the effects generated by TMS• Motor cortex
o Twitches can be observed
• Primary visual cortex
o Generates phosphenes - 4What happens if the magnetic pulse is lower that that to create a phosphene• Current causes neurons to fire randomly and thus increases the level of neural noise which causes the masking of neurons that are firing correctly by these random neurons
• These means that an area ceases to function correctly usually the processing is not totally disrupted - 5What are the advantages of TMS• It produces a focal lesion where and when you want it and moreover does not give the brain time to recognise
• Does not give the subject the time to learn compensatory behaviours and thus the resulting impaired behaviour is more accurate than analysing real life lesions
• Due to short lived TMS lesions the subject can be his own control which is the perfect match - 6Summarise the Ammasin et al experiment• Patients were presented with trigram and initially checked to see if they can see
• Zapped at different intervals
• To ensure the zap had effect you had to wait 10 sec so that the signal enters and interrupts processing
• There were no phosphenes as the voltrage was too low
control experiment was to zap another part of the brain not invovled in interprating the trigram. if the trigram is seen it is not the neck muscles impinging of reading - 7Summarise the second experiment done by Ashbridge et al .After the first experiment Ashbridge et al tired two trigrams. Normally when secodn trigram is presnted the first one is masked straightaway. When TMS is done 100 ms after 2nd trigram the first is seen. the correct hypothesis states that htis is because processing is done else where and when TMS is carried the second trigram can't prcocess as it blocked theremfoe we can see first tirgram
- 8Describe the mastermap hypothesis and how TMS was used to prove itV1 is high resolution
MT ismotion
V4 COLOUR all correlated in V1 to give colour
object to be perceive
Lets take a red disk
• V1 would register the location of the disk as it is area with high resolution
• MT would analyse the motion of the disk
• V1 takes this information
• Neither MT or V4 can individually allow visual awareness as such V1 needed
• Thus deactivating this V1 would disrupt visual awareness
Pascual –Leone Walsh - 9Descirbe the work of Pascual Leone wasljStimulated MT subkects saw moving phosphenes . Stimulated MT/V4 bt inhibited V1 no phospheses V1 is thus proven to be the master map
- 10How did ashbridge prove feature search required attnetion and conjucntio ndid notInhibited attnetion and measured the times taken for both. Inhibiting righr pariteal lobe had no effect on feautre search but did not conjunctio
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- UNIVERSITY OF MELBOURNE (Data Analysis and Imaging Techniques ( Lecture 5- 12) - Pier) BIOPSYCH Fichas sobre TMS - LECTURE 9-10, creado por reesha.cornelio1 el 10/06/2015.
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