of a criminal charge based upon interrogation and evidence can be a difficult and indeterminate process. Polygraphy is limited by reliance on peripheral manifestations
of anxiety (skin conductance, heart rate, and respiration), which can to certain extents be circumvented. Scalp-recorded event-related potentials (ERPs) reflect neuronal activity associated with a sensory, motor,
or cognitive event. The P-300 wave of the ERP appears in response to rare, meaningful stimuli, and its amplitude and latency
has been associated with deception (lying on the Guilty Knowledge Test, GKT). This suggests that the cognitive differences
between lying and telling the truth could be associated with changes in other correlates of brain activity, such as regional
cerebral blood flow Unfortunately, the ESP provides high temporal but no spatial
resolution in the brain
Since deception-induced mood
and somatic states may vary across individuals, a marker of deception independent of anxiety or guilt is important. Regional
brain activity, manifest as a blood oxygenation level dependent (BOLD) response. elicited by inhibition of the truth response during intentional deception
has been demonstrated to serve as such a marker. Unlike the ERP, the spatial
resolution of BOLD event-related (questioning) functional MRI
neuroimaging is sufficient to anatomically localize changes in cerebral blood flow related to regional neuronal activity during
Langleben and colleagues (2002)
studied fMRI contrasts between deceptive and truthful responses. Responses of 18 participants performing the GKT were measured
and analyzed using statistical parametric mapping. They found that deceptive responses were associated with increased activity
in the anterior cingulate cortex (ACC), the superior frontal gyrus (SFG), and the left premotor, motor, and anterior parietal cortex. This indicated that cognitive differences between deception and truth have neural correlates that
can be detected by fMRI.
Wyland and colleagues (2003) found that suppression of a particular thought, when compared to free-thought control
condition, revealed greater activation in the anterior cingulated area of the brain. When the task of suppressing all conscious
thoughts was compared to free-thought, a more distributed network of brain regions, including the anterior cingulate and the
insula, was activated.
Soltnick and Schacter (2004)
used fMRI to study truth and false visual recognition. They found a preferential truth recognition activity in early visual
processing regions of the brain. In fact, their research implied that the sensory signal distinguishing truth from deception
may not be accessible to conscious awareness, indicating that intentional deception can be identified.
Cognitive Engineering uses
specifically developed imaging and analysis algorithms and customized interrogation protocols to fit the individual situation.
Cognitive Engineering can apply these techniques for forensic purposes to individual circumstances. We will be pleased to discuss how fMRI can be applied to your individual case circumstances.
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