Subliminal versus supraliminal stimuli activate neural responses in anterior cingulate cortex, fusiform gyrus and insula:a meta-analysis of fMRI studies

Background: Non-conscious neural activation may underlie various psychological functions in health and disorder. However, the neural substrates of non-conscious processing have not been entirely elucidated. Examining the differential effects of arousing stimuli that are consciously, versus unconsciously perceived will improve our knowledge of neural circuitry involved in non-conscious perception. Here we conduct preliminary analyses of neural activation in studies that have used both subliminal and supraliminal presentation of the same stimulus. Methods: We use Activation Likelihood Estimation (ALE) to examine functional Magnetic Resonance Imaging (fMRI) studies that uniquely present the same stimuli subliminally and supraliminally to healthy participants during functional magnetic resonance imaging (fMRI). We included a total of 193 foci from 9 studies representing subliminal stimulation and 315 foci from 10 studies representing supraliminal stimulation. Results: The anterior cingulate cortex is significantly activated during both subliminal and supraliminal stimulus presentation. Subliminal stimuli are linked to significantly increased activation in the right fusiform gyrus and right insula. Supraliminal stimuli show significantly increased activation in the left rostral anterior cingulate. Conclusions: Non-conscious processing of arousing stimuli may involve primary visual areas and may also recruit the insula, a brain area involved in eventual interoceptive awareness. The anterior cingulate is perhaps a key brain region for the integration of conscious and non-conscious processing. These preliminary data provide candidate brain regions for further study in to the neural correlates of conscious experience

Proverb interpretation in fluent aphasia and Alzheimer's disease: Implications beyond abstract thinking

This study compared proverb processing across three groups, i.e. patients with fluent aphasia (APH), patients with Alzheimer's Disease (AD), and normal control subjects (NC). Proverb stimuli were used to examine the effects of group membership and proverb familiarity in two presentation formats (i.e. spontaneous versus multiple-choice) on performance. The sensitivity of cognitive measures as predictors of ability to interpret proverbs was also investigated. In relation to NC subjects, patients with fluent APH exhibited significant difficulty formulating responses for familiar and unfamiliar spontaneous proverbs, whereas patients with AD demonstrated lower performance only on the unfamiliar proverbs. On the multiple-choice paradigm, however, patients with APH exhibited minimal difficulty. Conversely, the patients with AD manifested significant problems selecting the correct abstract response for familiar proverbs. With regard to predictors, language was relevant to familiar proverb interpretations and to proverbs presented in the spontaneous format. Cognition was a sensitive predictor for unfamiliar proverb interpretations and to the multiple-choice format. Deficits on the proverb tasks are discussed with reference to the potential breakdown of underlying linguistic and cognitive processes. The present data support the diagnostic value of proverbs in elucidating brain- behaviour relationships

Rearrangements of Spiropentyl Cation

The structures of spiropentyl cation and its rearrangement products have been studied via ab initio geometry optimization at the MP2/6-31G* and B3LYP/6-311G* theoretical levels with additional calculations at the MP4/6-311G* level. The cation was calculated to be a transition state and underwent a cyclopropylcarbinyl to cyclobutyl cation rearrangement. This led to the products observed in the nitrous acid deamination of spiropentylamine. A closely related transition state, with the second cyclopropyl ring rotated 20° from the normal Cs geometry, was located. It led to a cyclopropyl cation type ring opening to an allyl cation, which formed the products observed in the solvolysis of spiropentyl chloride. The two transition states have essentially the same energy

Atomic Energy Commission Reports

Report regarding the structural evaluations made of the upper head of the Experimental Gas Cooled Reactor (EGCR). This report includes descriptions of the model, experimental procedures, and analyses of the results. Appendix begins on page 139