Dr. Grossi's Blog

Synchronized Viewing

Dr. Philip Grossi
Sunday, 29 August 2010

illustration to synchronized viewing blogWhen I turned on the television about ten days ago, I came across the movie classic The Good, the Bad, and the Ugly  with Clint Eastwood.  As I watched for a few moments, I was reminded of several articles  I read over the last eight or nine years..  After a little research I found them. In the last of those papers, Hasson and colleagues had subjects watch a 30 minute segment of  The Good, the Bad, and the Ugly  and record the fMRI signals that are sent to the brain.  They took two participants, who watched the same segment,  and asked whether the signals from one fMRI could predict the fMRI signals from the second participant.  They found that about 30% of  cortical activation signals from one participant could predict the fMRI signals from the paired participant.  They then converted each brain into a common coordinate system allowing the location in one person's brain to be aligned with the same locations in the second persons brain.  They demonstrated a degree of correlation in brain activation that suggests that  individual brains "tick together" in synchronized patterns when exposed to the same visual stimulus i.e., the movie. This study is different than earlier studies of Nancy Kanwisher and J.V. Haxby in which a more controlled and fixed stimuli are presented and the subject is asked to perform some task in response.  Hasson is presenting a situation that is more akin to real life. 

How is it possible for one brain to predict another as well as apparently they do?  They separated very emotionally stimulating scenes (gunshots) and found that these area produced substantial brain activation. Possibly then they are measuring emotional stimulation or attention that people would share. However, they also took out these areas and still found a correspondence of almost 25%.  They further confirmed that the fusiform face area strongly responds to faces as Kanwisher found in 1997.  They also found that a region of the collateral  sulcus was stimulated by indoor and outdoor scenes. Hassan also turned upside down the customary analysis and used the signal amplitude of response to predict  what type of stimulus to expect.  They also found there were some areas of the cortex that were not involved including the parietal and frontal. 

A terrific piece of work.