The Good, the Bad, and the Ugly

Research team:
Dr. Uri Hasson, Prof. Rafi Malach
The Department of Neurobiology, Weizmann Institute of Science, Rehovot

Background
One of the primary goals of brain research is to understand how our brains process the complex sensory stimulation that we encounter in our natural environment. However, many researchers exploring this phenomenon present individuals with simple, artificial stimuli with the aim of activating specific areas of their brains. Using these kinds of stimuli also simplifies the researchers' analysis of the results. Dr. Uri Hasson and Prof. Rafi Malach chose to examine the brain activity of individuals while they watched a movie ("The Good, the Bad, and the Ugly"), one that contains highly complex visual and auditory information and simulates the input we receive from our natural environment.

Research Questions
What is the appearance of brain activity in response to "natural" input?
Does similar activity occur in the brains of different individuals in response to the same natural input?

Research Methods
The technology used in this research was fMRI-functional magnetic resonance imaging-a method based on the fact that active nerve cells make use of energy, and one indication of this energy use is the level of oxygen in the blood. The magnetic characteristics of the blood's hemoglobin, which carries the oxygen, change depending on whether or not oxygen is present. By measuring the corresponding magnetic signals through instruments placed on a person's head, researchers can monitor the active areas within the brain under different conditions.

In a typical experiment, the individual lies inside a large electromagnet (as shown in the illustration) and performs certain tasks, such as watching visual stimuli and listening to auditory stimuli. The visual images are transmitted to the magnet optically, so that the computer generating the images and the screen on which they appear are not affected by the magnetic field. A second computer continually records the measurements of brain activity and later analyzes the data collected.

This research is unconventional both in its experimental design and the methods it uses to analyze results. For one, it measures brain activity while the participants are viewing a segment of a movie. This stimulus is complex and "natural," in contrast with the simple and artificial stimuli, such as static pictures, used in conventional research. Its methods of data analysis are also unique. The usual method is to start with a predetermined series of simple stimuli and look for the areas of the brain that are activated by each separate stimulus. Here, the researchers took the opposite approach. They presented the brain with a complex stimulus consisting, essentially, of a wide variety of different stimuli. Then, they looked for the moments in the movie during which the greatest amount of brain activity was recorded. In this way, for each area of the brain examined, the researchers were able to characterize the type of stimulus to which that area was sensitive.

The Experiment
Five individuals participated in the experiment. All viewed the same half-hour segment of the movie, "The Good, the Bad, and the Ugly." As they watched, the researchers measured their brain activity using functional magnetic resonance imaging.

Results of the Experiment
One of the major findings of the experiment was that approximately 30 percent of the brain areas functioned in similar ways for different participants as they watched the movie. In other words, the researchers were able to use an activity pattern that they observed at a particular moment in time for one participant in order to predict an activity pattern for another participant.

In follow-up research, Dr. Hasson found that for highly suspenseful movies, like Alfred Hitchcock's, even greater similarity was evident in brain activity: 70 percent of the areas in the brain functioned similarly for different participants.

Another key finding was that it was possible to identify specific "areas of responsibility" for different areas of the brain. The diagram below indicates brain activity in an area called FFA.

Diagram A

If we look at the moments in the move that produced the greatest activity in this area, we can see that they are when faces appear. The diagram shows individual frames from the movie at the moments in time when the greatest brain activity was recorded. The frames are numbered according to the level of activity, in descending order (with the first picture representing the highest level of brain activity). In this same way, the researchers characterized brain areas related to spatial orientation, interpretation of dialogues, and interpretation of hand movements.

Diagram B

The research also showed that different types of movies activate the areas of the brain in different ways. There is a correlation between the brain's level of activity and the degree of arousal or interest created by the movie.

Discussion and Conclusions
Although the participants watched a complex movie and were given no instructions by the researchers, significant findings were achieved regarding the nature of brain activity.

The researchers found striking similarities in the brain activity of the participants who viewed the movie. They noted high correlations not only for brain areas that process initial sensory information, but also for areas in which higher-level information processing, such as face recognition, takes place.

By choosing this unconventional method of analyzing their data, the researchers were able to characterize the functional responsibilities of different areas of the brain. The research supported previous findings about these areas and also discovered new information about brain functioning.

More about...
The Research Methods - Research methods are the collection of tools that a scientist uses to find an answer to his or her research question. These methods determine, among other things, the experimental design, the system for gathering and analyzing data, and the theoretical basis for constructing models. Scientists attempting to answer the same research question may use different research methods to do so. Occasionally, there are problems with the reliability of measurements produced by a particular method, and an alternative method, or combination of methods, must be used to collect and analyze the data. One method may allow scientists to measure only a single variable, while another allows them to measure a whole host of variables. Creative research methods have sometimes been the key to scientific breakthroughs.