Back when I was a youngin’, I dearly loved the characters Pinky and the Brain from the Animaniacs show; eventually the megalomaniacal rodent and his unique friend spun off into their own dedicated series. One of my favorite childhood memories is of the charmingly surreal segment where Pinky and the Brain sing about the parts of the brain to the melody of Camptown Races. Mo over at the neurophilosophy blog found a YouTube video of the segment, which I’ve pinned below. The neurophilosophy blog also has a transcript of the lyrics. A quick bit of trivia: Maurice LeMarche, who performed the voice of the Brain, also did the voices of Kif, Calculon, and Hedonism Bot in Futurama. Now you know!
According to an announcement (pasted below) on visionlist, the current issue of Advances in Cognitive Psychology is a special issue all about visual masking. The issue (consisting of 27 papers) is entirely free to download, and seems to be a pretty nice overview of recent research in the field.
We are pleased to announce the publication of a special issue of the journal Advances in Cognitive Psychology on "Visual masking and the dynamics of human perception, cognition, and consciousness." Guest editors for the special issue are Ulrich Ansorge, Greg Francis, Michael Herzog and Haluk Öğmen. The 27 papers in the special issue derived from a workshop that was held at the Hanse-Wissenschafts Kolleg in Delmenhorst, Germany. The workshop brought together an international group of researchers to present state-of-the-art research on dynamic visual processing with a focus on visual masking. This special issue provides a contemporary synthesis of how visual masking can inform the dynamics of human perception, cognition, and consciousness. The various papers discuss empirical studies of perception, theoretical challenges, computational models, and neuroscience techniques. The special issue is available free of charge on-line at: http://www.ac-psych.org/?id=2&rok=2007&issue=1-2 -Greg Francis Professor of Psychological Sciences Purdue University http://www.psych.purdue.edu/~gfrancis/home.html
I recently added the ‘Friend Wheel’ application to my Facebook profile, and I’m rather fascinated by the results:
I think there’s some issues with their ordering, but you can still clearly see three distinct groups with high within-group linkage. The three groups line up pretty nicely with people I know from high school (LMHS), people I know from my undergrad at Carnegie Mellon, and people I know from grad school at Caltech. There’s also some interesting between-group linkages — for example, I had no idea that my friend Andy from Caltech knew my friend Ashley from CMU.
It looks like all the abstracts from the Vision Sciences Society conference we were at a few months ago have now been published in the Journal of Vision. Below is the text of the abstract for the poster I presented. If you have any questions, please leave a comment!
We have previously demonstrated that transcranial magnetic stimulation (TMS) can cause the re-perception of recently presented visual stimuli. Here we find that such replays can be experienced for natural scene stimuli, with a level of detail suggesting low-level rather than iconic representations.
TMS was administered using a Magstim dual-pulse setup sending pulses with 50 ms separation through a figure-8 coil. The coil position over occipital cortex was optimized to elicit vivid flashes of brightness (phosphenes) in a darkened room. We screened subjects to find those that perceived large, bright phosphenes near fixation. To these subjects (N=7), we presented pictures of natural scenes and animals for 100 ms, followed by TMS at various ISIs. Subjects provided verbal descriptions, subjective ratings, and drew figures on the screen.
While TMS in a stable visual environment generally elicits phosphenes that are consistent across trials, colorless, and internally featureless, we found that TMS delivered shortly after image presentation led to the perception of clearly defined forms that varied according to the content of the flashed image.
In this experiment, five out of the seven subjects reported percepts that drew from the preceding images. In the most vivid cases, these would appear to be nearly photographic repetitions in portions of the display. In other cases, subjects would perceive uniformly-filled, phosphene-like figures whose outlines matched, in detail, contours drawn from the preceding image (abstract by Wu et. al. describes double-blind validation of these effects). In early trials, subjects experienced the most vivid replay effects within narrow time windows, which varied from subject to subject between 150-250 ms. With continued stimulation, longer ISIs (as much as one second) became effective.
This study indicates that rich, detailed visual information remains encoded well after visual perception has ended, and that TMS can allow conscious access to these nascent low-level representations.
Also, here’s the abstract for our complementary poster: TMS “instant replay” validated using novel double-blind stimulation technique
After a hiatus of more than a year, I’ve decided to try reactivating this jolly ol’ blog. As before, my plan is to periodically share commentary on various interesting happenings in neuroscience and artificial intelligence.
As for myself, for the past year I’ve been doing research using transcranial magnetic stimulation (TMS) to reactivate recently-viewed visual percepts in occipital cortex. The basis of the work can be found in the PhD thesis of my colleague Daw-An Wu, titled “How perception adheres color to objects and surfaces : studies using visual illusions and transcranial magnetic stimulation.” At some point I’ll elaborate on the directions we’ve been pursuing in the past year, which have had some rather fascinating results.