TMS and Perception (3)

Question 1

What are the different types of journal articles?

Answer 1

• general: all fields, very influential articles
• field
• sub-field
• specialized

Question 2

What is the impact number?

Answer 2

• impact or influence of the journal calculated by the average of how often an article is cited in a year

Question 3

What are the different journal distribution models?

Answer 3

• traditional: free to submit articles, cost to receive

- open-access: cost to submit articles, free to receive

Question 4

What are the pros and cons of traditional journal distribution models?

Answer 4

• pros: rigourous peer-review and high quality to increase sale
• cons: expensive, limited access

Question 5

What are the pros and cons of open-access journal distribution models?

Answer 5

• pros: unlimited free access to everyone

- cons: incentive to accept submissions (some called predatory journals and will publish anything)

Question 6

What is the organization of an original research article?

Answer 6

• IMRaD hourglass organization
• introduction
• methods
• results
• discussion/conclusion

Question 7

What journal was Pascual-Leone and Walsh (2001) published in?

Answer 7

• Science

Question 8

What is Pascual-Leone and Walsh (2001) research question?

Answer 8

• What role do backprojections from the motion area to primary visual cortex play in the visual awareness of motion?

Question 9

What is the organization of the visual system?

Answer 9

• serial, parallel and recurrent processing
• info flows forwards and backwards
• dorsal/how stream
• ventral/what stream

Question 10

What areas were the researchers focused on?

Answer 10

• V1: primary visual cortex
• MT/V5: motion area
• info travels up to MT/V5 but also backprojects from MT/V5 to V1

Question 11

What is visual awareness? How do we operationalize it?

Answer 11

• being aware or conscious of what is around you

- if one is able to self-report it

Question 12

How was V5 calibrated?

Answer 12

• identified scalp location for induction of moving phosphenes (flash of light that happens with TMS stimulation)
• identified minimum field strength for consistent induction of moving phosphenes

Question 13

How did the researchers calibrate V1?

Answer 13

• identified scalp location for induction of stationary phosphenes in same perceived location as moving phosphenes
• identified minimum field strength for consistent induction of stationary phosphenes

Question 14

What TMS stimulus did the researchers use?

Answer 14

• single pulse test stimulus to V5 at 100% threshold to induce moving phosphene
• single pulse conditioning stimulus to V1 at 80% threshold to not induce stationary phosphene

Question 15

What was the time between the pulses called?

Answer 15

“V5-V1 asynchrony” or “Conditioning to test asynchrony”

Question 16

What would the participants report?

Answer 16

• 1: moving phosphene same as with single V5 TMS
• 2: moving phosphene, but not as clear as single V5 TMS
• 3: phosphene in same location as V5 TMS but not moving
• 4: no phosphene

Question 17

What is the independent variable and dependent variable of this study?

Answer 17

• IV: V5-V1 asynchrony

- DV: phosphene report

Question 18

What are the results of the V5 to V1 experiment?

Answer 18

• when reading figure: 0 means pulses were at same time, positive is how long after V1 is to V5
• pulse of V1 at 25 ms after V5, interfers with awareness of moving phosphene

Question 19

What do the results of the V5 to V1 experiment suggest?

Answer 19

• feedback to V1 is necessary for visual awareness of motion
• interference in V5 due to forward projections from V1 to V5
• backward masking of motion phosphenes by later stationary phosphenes

Question 20

What are the methods of the V5 to V5 experiment?

Answer 20

• single-pulse test stimulus at 100% to V5
• single pulse conditioning stimulus at 80% to V5
• time between called “conditioning to test asynchrony”

Question 21

What results were seen in the V5 to V5 experiment?

Answer 21

• a secondary pulse to V5 does not interfere with the perception of motion in any way

Question 22

What do the results from the V5 to V5 experiment indicate?

Answer 22

• rules out the interference in V5 due to forward projections from V1 to V5 in previous experiment
• it is unclear why TMS to V5 does not disrupt visual awareness of motion

Question 23

What is the researchers conclusion?

Answer 23

• Our results highlight the importance of the fast feedback projections from V5 to V1 in visual awareness of motion and document the chronometry of the phenomenon

Question 24

Why is TMS the only possible method to conduct this experiment?

Answer 24

• a lesion to V1 would just cause vision loss
• EEG and fMRI not able to block
• TMS is able to block a specific area for a shortened time

Question 25

What are some potential issues with this study?

Answer 25

• backward masking of motion phosphenes by later stationary phosphenes? but no reports of multiple phosphenes
• 18 of 26 participants excluded for failure to perceive reliable V1 or V5 phosphenes
• localization: V1 or nearby areas actually being affected

Question 26

What are some possible follow up questions?

Answer 26

• Does V1 play a similar role for other visual phenomena? (colors, shapes, faces)
• Does V1 play a similar role for visually presented motion stimuli?