A Pilot Study of Functional Magnetic Resonance Imaging Brain Correlates of Deception in Healthy Young Men

Ten healthy adults (8 men, 2 women) were recruited and consented for the study, which was approved by the Medical University of South Carolina Investigational Review Board. One woman we scanned had a variation in her exposure paradigm. Thus, we chose not to include the other woman and restrict our analysis to a single gender. Subjects were required to be 18 to 40 years old and right-handed and score at least 9 out of 12 on the Annett Handedness Rating Scale.²⁸ They also had to be able to read and write English and possess the capacity to provide informed consent. Potential subjects were excluded if they had a history of any current or past Axis I Psychiatric Disorder (except simple phobia), including substance abuse/dependence as determined by the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I), a history of neurologic disease, a currently unstable medical condition, any psychotropic medication taken within 5 half-lives of procedure time, caffeinism, nicotine use, any metal implants (not including dental fillings) making an MRI unsafe, irremovable medical devices such as pacemakers or fixed hearing aids, presence of shrapnel, previous inability to tolerate MRI procedure, or claustrophobia severe enough to induce substantial anxiety in closed spaces.

After written consent was obtained, subjects were evaluated with SCID and Annett Handedness scales.²⁸ The subjects underwent a physical exam and review of current and past medical history.

On a subsequent visit, the subjects were escorted to two rooms: one was referred to as the truth room and the other the deception room. The order was randomized with one-half of the subjects going to the truth room first and the other half going to the deception room first. Within each room, subjects were instructed to find under which of five objects a fifty-dollar bill was hidden. They were to remember the location of the money and leave it in place. The subjects were then placed in the MRI scanner with goggles to view pictures of objects in the truth and deception rooms. Electrodermal electrodes were attached to the left hand, and the data (sampling rate 100 per second) were recorded using LabView 5.0.1 on a G4 Macintosh (For details see Shastri, 2001).

The images were acquired using a Picker Edge 1.5T MRI scanner equipped with an actively shielded magnet and high performance whole-body gradients (27 mT/m, 72 T/m-sec). A 15-slice TE20 structural scan was obtained to evaluate structural pathology. The BOLD fMRI consisted of 15 coplanar axial slices covering the entire brain and positioned parallel to the anterior commissure-posterior commissure line using a sagittal scout image. Each fMRI volume consisted of BOLD weighted axial scans and used an asymmetric-spin gradient echo, echo-planar (EPI) fMRI sequence (tip angle=90° TE 45.0 ms; TR 3000 ms; fifteen 8 mm thick / 0 mm gap axial slices; FOV 300 × 300 mm; in-plane resolution 2.109 × 2.109 mm; through-plane resolution 8 mm; frequency selective fat suppression). Given these parameters, for the fMRI, a set of fifteen 8 mm thick / 0 mm gap axial slices covering the entire brain was obtained every 3 seconds.

While the BOLD fMRI scans were being acquired, a modified Control Question Test paradigm was utilized and required subjects to give both truthful and deceitful answers about the location of the money. Through video goggles connected to a computer, the subjects were shown prompt screens and then pictures of the objects in the rooms where the money had been hidden (Figure 1). If the subjects first looked in the truth room, then they were shown only the truth room objects first and then the deception room objects and vice versa if subjects were first shown the deception room. There were five objects in each room (ten unique objects in all), and the objects were each shown one time in a block for a total of four blocks per room. (Table 1) The order of the objects was randomized within each block. Before the picture of the first object and between the pictures of every object in the room, a prompt screen was displayed that reminded the subjects of the instructions. The object and the prompt were each displayed for 10.2 seconds. Subjects were instructed to raise either one (yes) or two (no) fingers to answer the question of whether the money was hidden under an object as soon as the object was visually displayed in the goggles. This was monitored and recorded by an observer (LR).

For the truth room, subjects were instructed to accurately report the location of the money by holding up the right index finger (one finger) when they were shown an object under which the money had been hidden. This would be the “control” with which the deceptive answers would be compared. This controls for the potential confounds of brain changes associated with simply seeing an object that had money under it. They were instructed to raise the right index and middle finger (two fingers) when shown an object under which the money was not hidden.

For the deception room, they were instructed to choose an object that did not have money hidden under it and respond affirmatively (right index finger), in effect creating a positive lie about the money location. They were also asked to respond negatively (right index and middle finger) to all other objects shown. They were thus consistently lying when the object with money hidden under it was shown (a hat). The money was hidden under the same object for all subjects. Subjects were told that a blinded investigator (to order of rooms visited and location of the money) would attempt to determine when they were lying by observing their behavior in the scanner through the control room window. If the subjects accurately reported the position of the money in the truth room, then they would receive 50 dollars. If the subjects “successfully” lied without being detected for the deception room, then they would receive an additional 50 dollars. In fact, all subjects were paid the full 100 dollars. This instruction was included in order to increase the motivation and the anxiety during deception.

The data were analyzed with MEDx 3.3/SPM96 on Sun workstations using the Talairach and Tournoux brain template throughout. Initially, the MEDx motion detection function was performed using the center of intensity weighting method. Any motion greater than 2.0 mm from reference volume would have been corrected using the MEDx 3.3 motion correction function (no subjects required motion correction, largest movement range 0.4 to −1.7 mm). Next, individual volumes were spatially normalized into Talairach space utilizing the SPM Module 96 in MEDx 3.3. Algorithm parameters included basic functions and smoothing x=4, y=5, z=1, iteration=2, smoothing=8.0, deformation=0.2, the SPM template corresponding to the original Talairach and Tournoux atlas²⁹ and output voxel size 4×4×4 mm. Using the SPM module again, spatial smoothing was performed using 8×8×8 mm gaussian kernel. Intensity normalization was performed which first created a with-in-the-brain mask that only included voxels if they had intensity greater than 35% the maximum of each image volume for all time points. The remaining nonzero voxels in each volume were then scaled in the time series to a mean value of 1,000. We then performed high pass temporal filtering which filtered out patterns greater than twice the cycle length of 204 seconds. Due to the SPM module performing another intensity mask during the upcoming SPM statistics step, a .tcl script was written to add 100 to all voxels outside the brain. When the SPM statistics was run, this ensured that no voxels we previously defined as within brain would be eliminated from the analysis but that voxels we previously defined as outside the brain would be eliminated.

Using the SPM module on MEDx 3.3, statistical analysis with a delayed boxcar design without temporal filtering was performed. The epochs were grouped as Lie (the time period when individuals gave a false answer—both indicating that the object did not conceal money when it did {4 epochs} and indicating the object concealed money when it did not {4 epochs}), Lprompt (time period prompt image displayed just prior to each Lie {8 epochs}), True1 (time period subjects answered truthfully the location of the money {4 epochs} and 4 truthful answers that the money was not under an object—temporally surrounding deceptive answers {4 epochs}), Prompt1 (time period prompt displayed immediately preceding True1 epochs), True (time period of all remaining truthful answers {24 epochs}), and Prompt (time period of prompt immediately preceding true epochs {24}). Using these epochs, Lie minus True1 and True1 minus Lie was computed with no threshold (p=0.05 and uncorrected k (cluster size) = 1). The individual unthresholded images were used to obtain group and individual activation profiles.

To calculate a group result, for all individuals, the image calculator in MEDx 3.3 was used to compute unthresholded Lie minus True1 z-maps containing both positive and negative z-scores. Thus, we used the image calculator to obtain the result of (Lie minus True1) minus (True1 minus Lie) z-maps for each subject. Once this was obtained for all individuals, they were summed and then divided by the square root of eight to create the group fixed effects analysis unthresholded z-map. The resulting image was then analyzed with MEDx 3.3 cluster detection with a minimum of z=1.645 and spatial extent threshold of 0.05. A low statistical threshold was chosen since our paradigm could only have a limited number of epochs of Lie. In addition, although we were directly testing our hypothesized regions, we were interested in analyzing the whole brain since we had no previous neuroimaging studies to focus our analysis. The resulting values were used to determine local maxima and visually present the significant clusters. The Talairach Daemon interface in MEDx 3.3 was used to identify locations of the local maxima.³⁰ In addition, the Talairach atlas²⁹ was used to confirm the location of the significant clusters. The Johns Hopkins University BRAID imaging database at http://braid.rad.jhu.edu/ index atlases.html determined the Damasio Talairach space definition of orbitofrontal cortex.

For the individual analysis, in a similar fashion to the group analysis, the unthresholded images of True1 minus Lie were subtracted from Lie minus True1. The resulting image was analyzed using MEDx 3.3 cluster detection with a minimum of z=1.645 and extent threshold of 0.05. The resulting values were used to determine local maxima and generate a visual representation of those significant clusters. The Talairach Daemon interface was used to identify location of the local maxima.³⁰ This was performed for each individual. In addition, the Talairach atlas²⁹ was used to confirm the location of the significant clusters.

The EDA data was converted to a text file by AS and AS. In order to correlate EDA with the functional BOLD signal, MEDx 3.3 analysis package requires an equal number of volumes and EDA data points. The EDA data corresponding to each volume (TR = 3 seconds) was therefore averaged using STATA. Thus, every sequential 300 EDA data points (sampling rate was 100 per second) were averaged to give 272 means that corresponded to the functional brain volumes to be compared. The volumes utilized were the ones that had been motion detected, spatially normalized, smoothed, intensity normalized, and temporally filtered (see above for details). Using MEDx 3.3, independent of the deception paradigm, the changes in EDA were correlated with BOLD fMRI changes using a Pearson's r correlation. This analysis was performed for each individual resulting in a z-map. One of the correlation z-maps was found to have a significant artifact and was not included in the individual or group analysis.

For the group analysis, the remaining seven individual z-maps were added using the MEDx 3.3 calculator and divided by the square root of seven. The resulting image was then analyzed with MEDx 3.3 cluster detection with a minimum of z=1.960 and spatial extent threshold of 0.05. In the direct BOLD comparison above (Lie minus True1), we were only able to use eight epochs. This study is thus underpowered relative to many in the field. For the correlational analysis, we were able to use all time points, and we were justified in using a larger z value threshold. The resulting values were used to determine local maxima and visually present the significant clusters. The Talairach Daemon interface in MEDx 3.3 was used to identify locations of the local maxima.³⁰ In addition, the Talairach atlas²⁹ was used to confirm the location of the significant clusters and the Johns Hopkins University BRAID imaging database for Damasio Talairach space definition of orbitofrontal cortex.

For the individual analysis, the individual correlation z-maps were each analyzed using MEDx 3.3 cluster detection with a minimum of z=1.960 and extent threshold of 0.05. The resulting values were used to determine local maxima and generate a visual representation of those significant clusters. The locations of the significant clusters were determined using the same technique as the group analysis.

Subjects consisted of eight healthy right-handed men (mean age 25 years with a range of 21-28) with no significant history of psychiatric or medical conditions. Average Annett Handedness score for right handedness was 11, with a range of 9 to 12. All subjects responded correctly in the deception room and correctly and truthfully in the truth room. Consistency of response was monitored, and all subjects reported that the same object for each block hid the money when it did not, although the objects chosen for this positive lie varied.

Group analysis for Lie minus True1 (Figure 2 and Table 2).

We generated group image maps to test our hypotheses regarding the functional neuroanatomy involved in deception. We then generated within-individual statistical maps to test for individual heterogeneity and the predictive capacity of imaging to detect deception.

Lie minus True1 is the subtraction that best isolates the act of deception by controlling for the most confounds. Our prestudy hypothesis was that the OFCx, AC, and the amygdala would show increased activation during this comparison. This comparison confirmed our hypothesis regarding the OFCx and AC, but failed to find amygdala activation. The other nonhypothesized regions (superior temporal gyrus, cerebellum, frontal gyrus), which met statistical significance, should be considered exploratory, as they were not hypothesized prior to the study

We next sought to examine the heterogeneity among our subjects in brain activation during the deception task. We examined each individual to determine whether they had significant activation in any of these regions during the deception minus true comparison. Using a minimum statistical threshold of z=1.645 and extent threshold of 0.05, one subject had no significant activation, while seven showed diverse activation patterns. No one brain region was found activated for all subjects when true epochs were subtracted from lie epochs. The mean number of discrete regions identified by the group analysis that were activated by individuals was 2 per individual subject with a range of 0 to 6.

For the group analysis, one of the subjects had significant artifact after the correlational analysis and was not included in the group analysis (Table 3 and Figure 3). Significant activation was found in the orbitofrontal and right anterior cingulate gyrus.

Thus, our prestudy hypothesis concerning the link between EDA changes during deception and OFCx and AC was supported, but again we failed to find amygdala activation. The other areas of activation that were not hypothesized can only be considered exploratory.

Of the seven subjects (one subject with significant artifact), six had significant (z >1.960 and extent threshold < 0.05) right orbitofrontal activation (Figure 4), and five had significant (z >1.960 and extent threshold < 0.05) right anterior cingulate activation. No other regions consistently activated across individuals.