From thoughtless awareness to effortful cognition: alpha - theta cross-frequency dynamics in experienced meditators during meditation, rest and arithmetic.

Neural activity is known to oscillate within discrete frequency bands and the synchronization between these rhythms is hypothesized to underlie information integration in the brain. Since strict synchronization is only possible for harmonic frequencies, a recent theory proposes that the interaction between different brain rhythms is facilitated by transient harmonic frequency arrangements. In this line, it has been recently shown that the transient occurrence of 2:1 harmonic cross-frequency relationships between alpha and theta rhythms (i.e. falpha ≈ 12 Hz; ftheta ≈ 6 Hz) is enhanced during effortful cognition. In this study, we tested whether achieving a state of 'mental emptiness' during meditation is accompanied by a relative decrease in the occurrence of 2:1 harmonic cross-frequency relationships between alpha and theta rhythms. Continuous EEG recordings (19 electrodes) were obtained from 43 highly experienced meditators during meditation practice, rest and an arithmetic task. We show that the occurrence of transient alpha:theta 2:1 harmonic relationships increased linearly from a meditative to an active cognitive processing state (i.e. meditation < rest < arithmetic task). It is argued that transient EEG cross-frequency arrangements that prevent alpha:theta cross-frequency coupling could facilitate the experience of 'mental emptiness' by avoiding the interaction between the memory and executive components of cognition.

The Role of Gesture in Supporting Mental Representations: The Case of Mental Abacus Arithmetic.

People frequently gesture when problem-solving, particularly on tasks that require spatial transformation. Gesture often facilitates task performance by interacting with internal mental representations, but how this process works is not well understood. We investigated this question by exploring the case of mental abacus (MA), a technique in which users not only imagine moving beads on an abacus to compute sums, but also produce movements in gestures that accompany the calculations. Because the content of MA is transparent and readily manipulated, the task offers a unique window onto how gestures interface with mental representations. We find that the size and number of MA gestures reflect the length and difficulty of math problems. Also, by selectively interfering with aspects of gesture, we find that participants perform significantly worse on MA under motor interference, but that perceptual feedback is not critical for success on the task. We conclude that premotor processes involved in the planning of gestures are critical to mental representation in MA.

On the role of visual experience in mathematical development: Evidence from blind mathematicians.

Advanced mathematical reasoning, regardless of domain or difficulty, activates a reproducible set of bilateral brain areas including intraparietal, inferior temporal and dorsal prefrontal cortex. The respective roles of genetics, experience and education in the development of this math-responsive network, however, remain unresolved. Here, we investigate the role of visual experience by studying the exceptional case of three professional mathematicians who were blind from birth (n=1) or became blind during childhood (n=2). Subjects were scanned with fMRI while they judged the truth value of spoken mathematical and nonmathematical statements. Blind mathematicians activated the classical network of math-related areas during mathematical reflection, similar to that found in a group of sighted professional mathematicians. Thus, brain networks for advanced mathematical reasoning can develop in the absence of visual experience. Additional activations were found in occipital cortex, even in individuals who became blind during childhood, suggesting that either mental imagery or a more radical repurposing of visual cortex may occur in blind mathematicians.

Neurocognitive mechanisms of mathematical giftedness: A literature review.

Mathematically gifted children/adolescents have demonstrated exceptional abilities and traits in logical reasoning, mental imagery, and creative thinking. In the field of cognitive neuroscience, the past studies on mathematically gifted brains have concentrated on investigating event-related brain activation regions, cerebral laterality of cognitive functions, functional specialization that is uniquely dedicated for specific cognitive purposes, and functional interactions among discrete brain regions. From structural and functional perspectives, these studies have witnessed both "general" and "unique" neural characteristics of mathematically gifted brains. In this article, the theoretical background, empirical studies, and neurocognitive mechanisms of mathematically gifted children/adolescents are reviewed. Based on the integration of the findings, some potential directions for the future research are identified and discussed.

Mathematics and mysticism.

Is there a world of mathematics above and beyond ordinary reality, as Plato proposed? Or is mathematics a cultural construct? In this short article we speculate on the place of mathematical reality from the perspective of the mystical cosmologies of the ancient traditions of meditation, psychedelics, and divination.

Femoral subtrochanteric shape variation in Albania: implications for use in forensic applications.

This paper investigates temporal trends in femoral subtrochanteric shape in Albanian skeletal material to evaluate levels of platymeria in a set of populations with European ancestry. Although flattening of the diaphysis in the subtrochanteric region has been associated with individuals of Native American and Asian ancestry, high levels of platymeria may not be unique to those groups. The forensic utility of Gilbert and Gill's (Skeletal Attribution of Race: Methods for Forensic Anthropology, University of New Mexico, Albuquerque, 1990) method for identifying ancestry from femoral subtrochanteric shape is examined using non-American skeletons of European ancestry. Femoral subtrochanteric anteroposterior and mediolateral diameters for Albanian skeletons from Apollonia (n=117) and Lofkënd (n=50) are assessed for temporal trends and then compared with published data using one-way ANOVA and post-hoc Tukey tests. High degrees of subtrochanteric flattening are identified in the Albanian samples and statistically significant temporal trends of decreasing platymeria are documented. Although recent publications suggest that subtrochanteric shape is less effective in identifying ancestry then was initially proposed, forensic anthropologists still commonly use femoral subtrochanteric shape to determine ancestry among skeletonized remains. This paper's findings support the assertion that proximal femoral morphology is functionally related, and more likely to be influenced by biomechanical adaptation and body proportions than genetic constraints.