thief get under a lie detector test .. at that time which part of his brain is active .. describe

Asked by  | 8th Jan, 2009, 12:50: PM

Expert Answer:

The act of lying or suppressing the truth triggers activities in the brain that send blood to the prefrontal cortex (located just above the eye sockets), which controls several psychological processes, including the one that takes place when a person crafts a new rather than a known response to something.

A technology called functional Magnetic Resonance Imaging (fMRI) technology is used to determine whether someone is fibbing by tracing blood flow to certain areas of the brain, which indicates changes in neuronal activity at the synapses (gaps between the neurons). If you're using fMRI, the scanner is detecting a change in the magnetic properties in the blood. More specifically, hemoglobin molecules in red blood cells exhibit different magnetic properties depending on the amount of oxygen they contain. The most active brain regions use—and thereby contain—the most oxygen.

Functional magnetic resonance imaging (fMRI) is a technology that measures changes in blood flow to different areas of the brain over time. Working neurons require more oxygen and thus more blood, just as working muscles do, so by tracking blood flow, fMRI shows which areas of the brain are most active at any particular moment.

An fMRI is a full body scanner. The subject is completely immersed by the machine, which contains microphones, speakers and a keyboard that enable him or her to communicate with researchers. Researchers compare images taken of the subjects at rest with those snapped after they had been asked to respond to a series of questions. The fMRI, images the actual processes involved in deception.

Many fMRI studies have concluded that a few key areas of the brain are more active during deception than truth-telling. These include the anterior cingulate cortex, which is involved in attention and monitoring processes, and the left dorsolateral and right anterior prefrontal cortices, areas of executive function involved in working memory and behavioral control.

Certain parts of the brain work harder to deceive, so there is  more oxygenated blood flow to those thousand voxels when subjects lie. It requires more brain activation to lie—although exactly why producing a deceptive versus a truthful response results in increased brain work is not known.

Answered by  | 8th Jan, 2009, 07:32: PM

Queries asked on Sunday & after 7pm from Monday to Saturday will be answered after 12pm the next working day.