FMRI lie detection

Psychiatrist and scientific researcher Daniel Langleben was inspired to test lie detection while he was at Stanford University studying the effects of a drug on children with attention deficit disorder (ADD).^[1] He found that these children have a more difficult time inhibiting the truth.^[2] He postulated that lying requires increased brain activity compared to truth because the truth must be suppressed, essentially creating more work for the brain. In 2001, he published his first work with lie detection using a modified form of the Guilty Knowledge Test, which is sometimes used in polygraph tests.^[3] The subjects, right-handed, male college students, were given a card and a Yes/No handheld clicker.^[4] They were told to lie to a computer asking questions while they underwent a brain scan only when the question would reveal their card.^[5][6] The subjects were given $20 for participating, and told they would receive more money if they deceived the computer; however, none did.^[7]

His studies showed that the inferior and superior prefrontal and anterior cingulate gyri and the parietal cortex showed increased activity during deception.^[8] In 2002, he licensed his methods for lie detection to the No Lie MRI company located in San Diego, California.

As "Prospects of fMRI as a Lie Detector"^[9] states, fMRIs use electromagnets to create pulse sequences in the cells of the brain. The fMRI scanner then detects the different pulses and fields that are used to distinguish tissue structures and the distinction between layers of the brain, matter type, and the ability to see growths. The functional component allows researchers to see activation in the brain over time and assess efficiency and connectivity by comparing blood use in the brain, which allows for the identification of which portions of the brain are using more oxygen, and thus being used during a specific task. This is called the blood-oxygen-level-dependent (BOLD) hemodynamic response.^[10]

FMRI data have been examined through the lens of machine learning algorithms to decode whether subjects believed or disbelieved statements, ranging from mathematical, semantic to religious belief statements. In this study, independent component features were used to train the algorithms, achieving up to 90% accuracy on predicting a subjects response, when prompted to indicate with a button press whether they believed or disbelieved a given assertion.^[11]

Activation of BA 40, the superior parietal lobe, the lateral left MRG, the striatum, and left thalamus was unique^[12] to truth while activation of the precuneus, posterior cingulate gyrus, prefrontal cortex, and cerebellum will be used to show a similar network for truth and lie.^[12] The most brain activity occurs in both sides of the prefrontal cortex, which is linked to response inhibition. This indicates that deception may involve inhibition of truthful responses. Overall bilateral activation occurs in deception in the middle frontal gyrus, parahippocampal gyrus, the precuneus, and the cerebellum.^[12] When looking into the different styles of lying we see differentiation in the locations of activation. Spontaneous lies require retrieval from the semantic and episodic memory to be able to quickly formulate a viable situation that remains in working memory while visual images are created to further hide the truth. The areas associated with this retrieval, the ventrolateral prefrontal cortex, anterior prefrontal cortex, and precuneus, are activated as well as the dorsolateral prefrontal cortex, anterior cingulate, and posterior visual cortex are activated. The anterior cingulate cortex is used for cross-checking and probability. For well-rehearsed, memorized, and coherent lies episodic memory activation is needed. This creates increased activation in the right anterior prefrontal cortex, BA 10, and the precuneus. The Parahippocampal cortex may be used in this process to generalize lies to situations because no cross-checking is needed. Newer studies have considered the salience of lying in a variety of situations.^[12] If a lie is of lower salience activation is broader and general while salient lies have specific activation in regions associated with inhibition and selection.^[13] Many areas are much more active in lying than truth possibly meaning its harder to retrieve false information compared to true memories^[9] because truth has more encoded retrieval cues. Interestingly, the limbic system, which is involved in many different emotional responses including the sympathetic nervous system, is not activated in deception.^[14]