TMS & Perception (3) Flashcards
What are the different types of journal articles?
-general: all fields, very influential and most impactful topics (ex. nature & science)
-field
-sub-field
-specialized
What is the impact factor?
the impact of influence of the journal calculated by the average of how often an article is cited in a year
What are the different journal distribution models?
-Traditional: free to submit articles, cost to receive (read)
-Open-access: cost to submit articles, free to receive (read)
What are the pros and cons of traditional journal distribution models?
-Pros: rigorous peer-review and high quality to increase sale
-Cons: expensive, limited access to scientific output (particularly to those outside of the academy or less wealthy countries)
What are the pros and cons of open-access journal distribution models?
-Pros: unlimited free access to everyone!
-Cons: incentive to accept submission (some called predatory journals and will publish anything)
What are some alternative journal distribution models?
-funding agencies (ex. NSERC in Canada) require open access after 12 months
-institutionally funded open-access journals
What is the organization of an original research article?
IMRaD hourglass organization
1) Introduction
2) Methods
3) Results
4) Discussion/ Conclusion
What journal was Pascual-Leone and Walsh (2001) published in?
Science
What is Pascual-Leone and Walsh (2001) research question?
what role do backprojections from the motion area to primary visual cortex play in the visual awareness of motion?
What is the organization of the visual system?
- serial, parallel and recurrent processing
- info flows forwards and backwards
- dorsal: “where/how” stream (where things are in the world relative to us. How we need to move to interact w/ them)
-ventral: “what” stream (what things are. Specific to faces)
What is serial processing
allows for only one object at a time to be processed
What is parallel processing?
various objects are processed simultaneously
What is recurrent processing?
information flows forwards and backwards
What areas were the researchers focused on?
- V1: primary visual cortex
- MT/V5: motion area
- info travels up to MT/V5 but also backprojects from MT/V5 to V1
What is visual awareness?
being aware or conscious of what is around you
How do we operationalize visual awareness?
If one is able to self-report it (report their experience or lack of experience of visual awareness of motion)
What is a backprojection?
information sent from a higher level area back down to a lower level area (ex. V5 to V1)
How was V5 calibrated?
-identified scalp location for induction of ‘moving’ phosphenes (flash of light that is experienced when TMS is applied to the visual cortex)
-identified minimum field strength for consistent induction of moving phosphenes
How was V1 calibrated?
-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
What was important when calibrating V1 and V5?
-the moving phosphenes evoked in V5 and stationary phosphenes evoked in V1 were occurring in the same location in the visual field
-allows you to be confident that you’re targeting the same location in the topographic maps in V1 and V5 (parts of the maps that represent the same location in the visual field)
What TMS stimulus did the researchers us?
-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
What was the time between the pulses called?
“V5-V1” asynchrony” or “Conditioning to test asynchrony”
What would the participants report?
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
What is the independent variable and dependent variable in this study?
-IV: V5-V1 asynchrony
-DV: phosphene report
What are the results of the V5 to V1 experiment?
-when reading figure: 0 means pulses were at the same time, positive is how long after V1 is to V5
-pulse of V1 at 25ms after V5, interferes with awareness of moving phosphene
What do the results of the V5 to V1 experiment suggest?
-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
What are the methods of the V5 to V5 experiment?
-single-pulse test stimulus at 100% to V5
-single pulse conditioning stimulus at 80% to V5
-time between called “conditioning to test asynchrony”
What results were seen in the V5 to V5 experiment?
a secondary pulse to V5 does not interfere with the perception of motion in any way
What do the results from the V5 to V5 experiment indicate?
-rules out the interference in V5 due to forward projections from V1 to V5 in the previous experiment
-it is unclear why TMS to V5 does not disrupt visual awareness of motion
What is the researchers conclusion?
- 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
Why is TMS the only possible method to conduct this experiment?
- 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
What are some potential issues with the study?
- 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
What are some possible follow up questions?
- Does V1 play a similar role for other visual phenomena? (colors, shapes, faces)
- Does V1 play a similar role for visually presented motion stimuli?
