I’ve decided to work on and post one (very) rough draft of each subchapter of my PhD thesis at a time, so that I can focus on just one part at a time without being distracted by the rest of it. I also find that I write best when writing for an immediate audience. Please feel free to ask any questions and give comments as I go along. I’ll start with the Table of Contents. As you can see, I’m experimenting with a Socratic/question-based approach to chapter organization:
Tentative title: Reactivation of Visual Representations With Transcranial Magnetic Stimulation
- What is this thesis about?
- What are the contributions of this work?
- How is this thesis structured?
- Background: TMS and visual cortex
- What do we already know about how information is represented in visual cortex?
- What is transcranial magnetic stimulation (TMS)?
- What does TMS offer us that other techniques do not?
- What is already known about how TMS interacts with representations in visual cortex?
- What can we learn from TMS reactivation of visual representations?
- Related work: Prior experiments with reactivation and related effects
- What related experiments were previously performed by Daw-An Wu and Juha Silvanto?
- How does the work described in this thesis build upon earlier work?
- Chapter: Replay of natural images
- How do you invoke the TMS-based visual replay effect?
- What was the methodology used for the natural image replay experiments?
- What do subjects report seeing when the replay effect is elicited?
- What are the implications of the figure-ground segregation reported by many subjects during replay?
- What is the timecourse of the visual replay effect?
- What do the effects of switching current direction in the coil tell us about the nature of the replay effect?
- What can we determine about what regions of cortex are being stimulated during visual replay?
- Chapter: Replaying visual masks
- What is visual masking?
- What can the replay of visual masks tell us about what is happening during replay?
- How did we replay visual masks?
- What happened when we replayed visual masks?
- What does the interaction between replay and visual masking tell us about the representation which gets reactivated?
- Chapter: entrainment effect and masking paradigm
- What is the entrainment effect?
- Chapter: retrieval?
- Chapter: Contributions and future work
- Future work
Don’t have access to the full details to determine how solid the results are, but it seems like an intriguing cognitive neuroscience study of cross-cultural differences:
There is evidence that the collectivist nature of East Asian cultures versus individualistic Western cultures affects both brain and behavior. East Asians tend to process information in a global manner whereas Westerners tend to focus on individual objects. There are differences between East Asians and Westerners with respect to attention, categorization, and reasoning. For example, in one study, after viewing pictures of fish swimming, Japanese volunteers were more likely to remember contextual details of the image than were American volunteers. Experiments tracking participants eye movements revealed that Westerners spend more time looking at focal objects while Chinese volunteers look more at the background. In addition, our culture may play a role in the way we process facial information. Research has indicated that when viewing faces, East Asians focus on the central region of faces while Westerners look more broadly, focusing on both the eyes and mouth.
Examining changes in cognitive processes — how we think — over time can provide information about the aging process as well as any culture-related changes that may occur. When it comes to free recall, working memory, and processing speed, aging has a greater impact than does culture — the decline in these functions is a result of aging and not cultural experience. Park and Huang note that, “with age, both cultures would move towards a more balanced representation of self and others, leading Westerners to become less oriented to self and East Asians to conceivably become more self-focused.”
While numerous studies suggest that culture may affect neural function, there is also limited evidence for the effect of cultural experiences on brain structure. A recent study conducted by Park and Michael Chee of Duke/National University of Singapore showed evidence for thicker frontal cortex areas involved in reasoning in Westerners compared to East Asians, whereas East Asians had thicker cortex in perceptual areas. Park and Huang observe that using neuroimaging to study the impact of culture on neuroanatomy faces many challenges. They write, “The data are collected from two groups of participants who typically differ in many systematic ways besides their cultural values, rendering interpretation of any differences found quite difficult.”
via Culture wires the brain: A cognitive neuroscience perspective.
More than 10 million Americans moved from one county to another during 2008. The map below visualizes those moves. Click on any county to see comings and goings: black lines indicate net inward movement, red lines net outward movement.
via Map: Where Americans Are Moving – Forbes.com.
This is a really interesting visualization showing from where to where people are moving around the country, based on IRS data.
I’ve added in support for drawing your own boxes (as many as you want!) into gwt-phys2d. It’s fun to try to do things like create a long see-saw shape and try to balance boxes on both sides. Check it out: http://gwt-phys2d.appspot.com/
If you try drawing enough boxes, you’ll find that performance doesn’t scale all too well (or at least it doesn’t on my netbook). I watched memory in the task manager and saw it repeatedly spike and fall back down, suggesting that it’s definitely the garbage collector which is eating up much of the time. I still haven’t had a chance to rewrite the phys2d code to stop creating so many new objects (esp. collision Arbiters) every frame, but I imagine that’ll improve performance considerably.
I’ve also created a Google Code and subversion repository for the project: http://code.google.com/p/gwt-phys2d/
If you’re interested in contributing let me know, and I’ll be happy to add you. Here’s a screen capture of the current version: