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MC > Task 9 > Flashcards

Task 9 Flashcards

1
Q

How does TMS work ?

A
  • > A brief, high amplitude pulse of current is discharge in a electromagnetic coil
  • > The change in electrical current in coil generates a magnetic field
  • > The magnetic field induces a secondary electrical current in the tissues
  • > neurons fire
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2
Q

Name the short version how the TMS work:

A

-> Electric current in stimulating coil produces magnetic field which produces current induced in brain

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3
Q

How does TMS deactivate a region of intrest ?

A
  • > Generally we are doing tak while applying TMS
  • > Neurons fire due to task (internal source ) and due to excitation induced by TMS (external source)
  • > The activation of internak source and external source corss cancel each other
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4
Q

What is a well known Metaphor for describing the effect of TMS ?

A

-> TMS signals are just like noise

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5
Q

What do we do with TMS ?

A
  • > Enhance cognitive function / treatment
  • > Identify functional specialization
  • > Functional integration ( how one brain region influences another )
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6
Q

What are in general side effects of TMS ?

A
  • > In general Effects of single TMS pulse are quickly reversible
  • > But :
    1. Epileptic seizures (if high frequency & intensity)
    2. Potential permanent physiological changes
    3. rTMS can cause suppression / unterdrückung of stimulated area that lasts for hours (usually mild)
    4. Stimulus intensity should always be defined according to individual cortical excitability
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7
Q

What is the SET UP of TMS ?

A
  • > Main power-pulse generation unit = Produce the high discharge current
  • > Electromagnetic Stimulating Coil = apply magnetic pulses up to several Tesla
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8
Q

What is important to know about the shape of the coil ?

A
  • > The shape and size determine how focal / focused the induced current is
  • > Small = more focal / stronger / but field strength decreases more rapidly
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9
Q

What is the most commonly used stmulating coil ?

A
  • > The butterfly / figure of eight coil

- > Important: the focal point of stimulation lies at the intersection of the two loops

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10
Q

Name another coil besides the figure eight coil:

A

-> Circular coil -> The focal ponts lays on the ring

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11
Q

How far can a TMS effect cortical areas ?

A

2 / 3 cm

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12
Q

Name one fact about spatial resolution:

A

-> Can not go to deep bcs stimulating deeper structures may also stimulate overlying cortex

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13
Q

Name so fact about the temporal resolution:

A
  • > Point of maximal activation: stimulated area will have its lowest signal-to-noise ratio with respect to the task it is trying to perform
  • > as neurons recover, the signal will increase
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14
Q

What is the impact of TMS on EEG and MEG signals ?

A

-> an effectively disrupted pulse will interfere with processes that contribute to the buildup of ERP/MEG signal (components)

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15
Q

What are the advantages of TMS over lesion studies ?

A
  • > Effects are brief and reversible / no plasticity
  • > Better temporal resolution
  • > Stimulated location can be removed or moved
  • > Within subjects design are doable
  • > More specific since damage can be controlled
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16
Q

What do lesion studies and TMS studies have in common ?

A

-> Both identify neccesisty of brain areas

17
Q

Which method is highly used in combination with TMS to infer the region to be actiavted:

A

-> FMRI

18
Q

What are the advanatges of lesion studies over TMS ?

A
  • > Subcortical lesions can be studied

- > Changes in behavior/ cognition are more observable in TMS mostly only present in reaction time

19
Q

What is the main advnatge of TMS ?

A

-> Effect are reversable and not long lasting

20
Q

What is are single pulse TMS ?

A
  • > Also know as event related TMS
  • > a single magnetic pulse is delivered at a precise time during a task
  • > TMS pulse is delivered in different time windows
  • > Provides information about the timing of cognition & and necessity
  • > Activation directly impacts brain
21
Q

What is meant by repetitive TMS ?

A
  • > a train of pulses is applied during the task
  • > Its about the effect after the stimulation
  • > Causes plasticity via high freuency and low frequency impulses
22
Q

What type of control condition do we use in TMS ?

A
  • > compare stimulation in critical and non-critical regions
  • > Task control (same region is stimulated but some aspects of the task have changed)
  • > compare performance when the same region is stimulated in critical and non-critical time windows
  • > Sham condition
23
Q

Why is TMS so cool ?

A

-> Because in TMS studies brain activity is the independent variable and task performance the dependent

24
Q

What does Sham condition mean?

A

-> Just using a fake coil as a control condition

25
Q

What is one major apppliaction for rtms

A

-> Treating depression via neuronla plasticity

26
Q

What do high frequency impulse lead to in rtms ?

A
  • > increased synaptic transmission efficiency (LTP)
  • > Cognitive enhancement
  • > everything above 1 HZ
27
Q

What do low frequency impulse lead to in rtms ?

A
  • > decreases synaptic transmission efficiency LTD

- > everything below 1 HZ

28
Q

What is a TDSC ?

A
  • > Instead of using magnetic fields it directly uses electrical fields
  • > uses a ver low current
  • > uses the flow of electrical charge from anode to cathodes
  • > With enough stimulation and repeated exposure the neurons will start to fire more enhancing a certain function
29
Q

What does anode mean ?

A

-> Positive side ( tends to enhance performance ) effected by GABA

30
Q

What does cathode mean ?

A

-> Negative side tends to disrupt performance:

31
Q

What are the benefits of TDCS ?

A
  • > Cheap
  • > Portable
  • > No side effect

MC (9 decks)

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