Abstract:

The objective of this study was to determine whether Single Photon Emission Computed Tomography (SPECT) imaging techniques could quantitatively differentiate brain activity levels between attention-focused and non-focused mental states in brain structures related to attention. Comparisons of SPECT data were made among five behavioral sub-groups of an adult male population diagnosed with attention deficit disorder (ADD): hyperactive, inattentive, over-focused, depressive, and explosive. Diagnoses were based on {\it DSM-III-R\/} and {\it DSM-IV\/} criteria, behavioral information from psychiatric intake examinations and interview, and managing physicians' evaluations. Cerebral SPECT images were obtained for both an attention-focused state (working on a series of simple arithmetic problems) and non-focused state (relaxed, no task). Software was written to uniformly and quantitatively analyze the SPECT images to determine relative activity of 33 regions of the brain. Using {\it t-test\/} and correlation analyses, participants rated highest (top quartile) in hyperactivity were found to have a 12\% {\it decrease\/} in anterior cingulate gyrus activity in the focused attention state compared to the non-focused state, whereas those rated lowest in hyperactivity (bottom quartile) showed an {\it increase\/} in cingulate gyrus activity of about the same amount. Results also showed the explosive subtype with lowered temporal lobe activity and the depressive subtype with lowered frontal cortex activity with respect to the other subgroups, in both focused and non-focused states. This research confirms earlier work on the role of the cingulate gyrus in selective attention, and raises important questions about the role of brain function in the control of the selective attention function in ADHD and whether deficits in this area might be the result of organic dysfunction. An organically dysfunctional attention system could have a significant impact on the ability of an individual to establish and sustain the focused and self-aware states that are often cited as important aspects of transpersonal experience.