Functional brain imaging: Evaluation of the effects of violent media exposure

Although there is mounting evidence that such exposure is detrimental to the emotional and physical well-being of children and youth, there is little information on the neurophysiological consequences of such viewing on the developing brain. In this review, by using various imaging techniques, the authors provide preliminary evidence that violent visual images may have a damaging effect on the frontal lobe function of young viewers. These preliminary findings, presented at a poster session of the Radiology Society of North America in 2002 should spur more research in children. The majority of studies have been conducted in adults with underlying neuropsychiatric disorders, not on naïve individuals, and have reported abnormal findings, particularly in the frontal lobes, when these subjects are exposed to violent images. Some questions that may be addressed in the future include whether the frontal lobe neurobiological changes observed by changes observed in the functional magnetic resonance images (fMRI) are transient or do they become permanent with excessive exposure; whether the age of the child is critical; whether the function is different between normal children and those with neuropsychiatric problems; whether there a difference in the function of the frontal lobes between viewing violent video games and TV programs, and ‘regular TV programming’; and does disruption of the frontal lobe function alter executive functioning and thus adversely effect long term academic performance? It is no longer debatable whether the child or adolescent viewer's exposure to violent media causes increased aggressive behaviour and contributes to youth violence. In addition to the well-established, large body of literature linking television violence to aggressive behaviour in children and young adults (1–3), recent studies confirm increases in both short and long term aggression caused by violent video games, with potentially more severe consequences on delinquent childhood behaviour than violent television programs (4,5). While the behavioural effects of media violence continue to be investigated, little research has been conducted to assess the neurophysiological effects of violent media exposure. The armamentarium of functional neuroimaging techniques, including functional magnetic resonance imaging (fMRI), magnetic resonance spectroscopy (MRS), positron emission tomography (PET) and single-photon emission computed tomography (SPECT), is ideal for such applications. The majority of functional and structural imaging research exploring brain function and aggression has been performed in adult violent offenders (6–8), and aggressive or violent adults with underlying psychiatric, personality or other organic disorders (9,10). Few functional imaging studies have been conducted evaluating aggression in children. The majority of these studies focus on aggressive children with disruptive behavioural disorders (attention deficit hyperactivity disorder, oppositional defiant disorder and conduct disorder) (11,12). These studies, whether in adults or in children, have identified abnormalities involving the frontal lobe. Specifically, depending on the functional imaging technique employed, decreased glucose metabolism (PET), N-acetyl aspartate and creatine/phosphocreatine (MRS), blood flow (PET and SPECT) and activation (fMRI) in the resting or task-activated state have all been described in the prefrontal cortex of the populations studied (6–12). In addition, a recent MRI volumetric study identified decreased pre-frontal cortical brain volume in adult subjects with antisocial personality disorder compared with substance dependent, psychiatric and normal controls (13). The results of the functional imaging studies described above are concordant with the results of neurophysiological and neurological studies conducted within similar population groups identifying prefrontal executive dysfunctions and abnormal anterior electroencephalography tracings, respectively (14). Even fewer functional imaging studies have detailed the effects of aggression and violent media viewing on the young brain. In a PET study performed on healthy adult volunteers, visual evocation of unrestrained aggression was significantly correlated with focal reductions in blood flow to the ventromedial frontal lobe compared with an emotionally neutral scenario (15). Although violent media was not evaluated in this experiment, this study does implicate frontal lobe alterations with aggressive emotion or imagery. Preliminary results from ongoing research presented at the Radiologic Society of North America identified decreased frontal lobe activation in aggressive, behaviourally disordered youths undergoing fMRI while viewing violent video games compared with normal controls (16). In addition, among the normal control subjects, brain activation patterns in youths with significant past violent media exposure were different from those with a minimal amount of past violent media exposure (17). This last observation is perhaps the most interesting and useful in the context of media violence and its effect on youth. Although the data are unpublished conference proceedings, this is the first functional imaging study correlating repetitive violent media exposure with alterations in brain activation. The exact implications of these preliminary findings are unknown. For example, the location (focal versus global) and type of alteration (increased or decreased function) in normal youths with significant past violent media exposure is not specified. Therefore, it is unknown whether the youths displayed decreased frontal lobe activation as has been described in behaviourally disordered aggressive adults and children, and in normal individuals imagining aggressive scenarios. Furthermore, in this scenario, the significance of decreased frontal lobe activation while viewing a violent video is unclear because decreased frontal lobe activation would be expected from violent video game viewing by itself. In addition, the temporal nature of the brain alteration is unknown. For example, the effects of past violent media exposure may be transient with ultimate normalization, as long as abstinence from viewing violent media exposure is maintained. Although many questions remain unanswered, these preliminary findings suggest that significant past violent media exposure has an effect on brain activation. Within the psychiatric domain, functional imaging research has elucidated the patterns of abnormal brain activation in schizophrenia, personality disorders, mood disorders and substance abuse (18). Functional MRI has also identified altered frontal lobe function in aggressive adults and youths with psychiatric, behavioural and personality disorders (9–12). With the explosion of the digital age, increasing youth violence from repetitive violent media exposure is a real and frightening concern. Functional neuroimaging remains an essentially untapped medium for the physiological evaluation of these effects on the brain. New preliminary findings suggest that brain activation is altered in normal youths with significant past violent media exposure while viewing violent video games (17). Additional functional imaging research will help clarify the relationship between violent media exposure, aggression and altered brain activation. Such elucidation may provide important organic evidence of the deleterious effects of violent video game exposure on children and youths, further highlighting the need for solutions to this growing problem.

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