Friday, February 09, 2007

Finding out beforehand what the intentions in our brains are:
Every working day, we make decisions that guide us through our daily lives. Each of these decisions are the products of emotional, cognitive and motivational dispositions acting out their neural concerts in specified regions of our brain. Most (not all) of these decisions are carried out based on pre-planned intentions that may sometimes be voiced aloud and sometimes not. John-Dylan Haynes from the Max Planck Institute for Human Cognitive and Brain Sciences (in cooperation with researchers from London and Tokyo) were able to isolate how and where the brain stores these intentions (the full paper is online here). Most of our secret intentions remain hidden in our brains and in our thoughts until we actually decide to carry them out at which point it becomes an action.

The researchers using a combination of functional magnetic resonance imaging (fMRI) and algorithms that inferred the intentions from patterns of neural activity obtained from the fMRI were able to decode the intention that the volunteers had in their heads without them uttering their inner thoughts. They also confirmed the long standing view that actions are not encoded in single neurons but in a whole spatial pattern of brain activity.

"They let subjects freely and covertly choose between two possible tasks - to either add or subtract two numbers. They were then asked to hold in mind their intention for a while until the relevant numbers were presented on a screen. The researchers were able to recognize the subjects intentions with 70% accuracy based alone on their brain activity - even before the participants had seen the numbers and had started to perform the calculation.
Participants made their choice covertly and initially did not know the two numbers they were supposed to add or subtract. Only a few seconds later the numbers appeared on a screen and the participants could perform the calculation. This ensured that the intention itself was being read out, rather than brain activity related to performing the calculation or pressing the buttons to indicate the response. "It has been previously assumed that freely selected plans might be stored in the middle regions of the prefrontal cortex, whereas plans following external instructions could be stored on the surface of the brain. We were able to confirm this theory in our experiments", Haynes explained.

The work of Haynes and his colleagues goes far beyond simply confirming previous theories. It has never before been possible to read out of brain activity how a person has decided to act in the future. The trick by which the invisible is made visible lies in a new method called "
multivariate pattern recognition". A computer is programmed to recognize characteristic activation patterns in the brain that typically occur in association with specific thoughts. Once this computer has been "trained" it can be used to predict the decisions of subjects from their brain activity alone. An important technical innovation also lies in combining information across extended regions of the brain to strongly increase sensitivity."

“Taken together, our results extend previous studies on the processing of goals in prefrontal cortex in several important ways. They reveal for the first time that spatial response patterns in medial and lateral prefrontal cortex encode a subject's covert intentions in a highly specific fashion. They also demonstrate a functional separation in
medial prefrontal cortex, where more anterior regions encode the intention prior to its execution and more posterior regions encode the intention during task execution. These findings have important implications not only for the neural models of executive control, but also for technical and clinical applications, such as the further development of brain-computer interfaces, that might now be able to decode intentions that go beyond simple movements and extend to high-level cognitive processes”

I am sure that this research will help improve the lives of paralyzed patients currently using brain computer interfaces (BMIs). Imagine a time when a BMI helping a paralyzed patient with motor deficiency would be able to read a complex intention like “I would like to go to the bedroom and rest awhile – robot can you make the bed for me?”…

I also remember reading somewhere (unfortunately I am not able to link to that paper, but will do so as soon as I ferret it out) that there is a time gap between the instant that an intention is formed in our brains and the time that we become consciously aware of the same. In fact I remember being a little perturbed by this fact. Imagine that neural patterns in the brain form an intention based on pre-existing dispositions that you have towards the subject and then you become aware of it - almost like a inner homunculus (albeit a diffuse one) making up decisions and revealing them to you later…

Papers of interest:

Reading hidden intentions in the human brain - John-Dylan Haynes et al.

Brain reading” with fMRI: Decoding of conscious and unconscious information processing
John-Dylan Haynes

Predicting the orientation of invisible stimuli from activity in the human primary visual cortex - Geraint Rees and John-Dylan Haynes; Nature neuroscience Volume 8 Number 5, May 2005

Predicting the Stream of Consciousness from Activity in Human Visual Cortex - Geraint Rees and John-Dylan Haynes; Current Biology, Vol. 15, 1301–1307, July 26, 2005

The cognitive neuroscience of individual differences - new perspectives

No comments: