Lateralized difference in tympanic membrane temperature: emotion and hemispheric activity

We review literature examining relationships between tympanic membrane temperature (TMT), affective/motivational orientation, and hemispheric activity. Lateralized differences in TMT might enable real-time monitoring of hemispheric activity in real-world conditions, and could serve as a corroborating marker of mental illnesses associated with specific affective dysregulation. We support the proposal that TMT holds potential for broadly indexing lateralized brain physiology during tasks demanding the processing and representation of emotional and/or motivational states, and for predicting trait-related affective/motivational orientations. The precise nature of the relationship between TMT and brain physiology, however, remains elusive. Indeed the limited extant research has sampled different participant populations and employed largely different procedures and measures, making for seemingly discrepant findings and implications. We propose, however, that many of these discrepancies can be resolved by considering how emotional states map onto motivational systems and further examining how validated methods for inducing lateralized brain activity might affect TMT

Superior Episodic Memory Is Associated With Interhemispheric Processing

The dependence of episodic memories on interhemispheric processing was tested. In Experiment 1, positive familial sinistrality (FS+; e.g., the presence of left-handed relatives) was associated with superior episodic memory and inferior implicit memory in comparison with negative familial sinistrality (i.e., FS-). This reflected a greater degree of interhemispheric interaction in FS+ participants, which was hypothesized as facilitating episodic memory. In Experiment 2, the authors directly manipulated inter- versus intrahemispheric processing using tests of episodic (recognition) and semantic (lexical decision) memory in which letter strings were presented twice within trial blocks. Semantic memory was superior when the 2nd presentation went to the same hemisphere as the 1st. Episodic memory, however, was superior when the 2nd presentation of a stimulus went to the opposite hemisphere. Results support an interhemispheric processing basis for episodic memories

Getting a Grip on Memory: Unilateral Hand Clenching Alters Episodic Recall

Unilateral hand clenching increases neuronal activity in the frontal lobe of the contralateral hemisphere. Such hand clenching is also associated with increased experiencing a given hemisphere’s “mode of processing.” Together, these findings suggest that unilateral hand clenching can be used to test hypotheses concerning the specializations of the cerebral hemispheres during memory encoding and retrieval. We investigated this possibility by testing the effects of a unilateral hand clenching on episodic memory. The hemispheric Encoding/Retrieval Asymmetry (HERA) model proposes left prefrontal regions are associated with encoding, and right prefrontal regions with retrieval, of episodic memories. It was hypothesized that right-hand clenching (left hemisphere activation) pre-encoding, and left-hand clenching (right hemisphere activation) pre-recall, would result in superior memory. Results supported the HERA model. Also supported was that simple unilateral hand clenching can be used as a means by which the functional specializations of the cerebral hemispheres can be investigated in intact humans

Findings of an effect of gender, but not handedness, on self-reported motion sickness propensity

Discrepant input from vestibular and visual systems may be involved in motion sickness; individual differences in the organization of these systems may, therefore, give rise to individual differences in propensity to motion sickness. Non-right-handedness has been associated with altered cortical lateralization of vestibular function, such that non-right-handedness is associated with left hemisphere, and right-handedness with right hemisphere, lateralized, vestibular system. Interestingly, magnocellular visual processing, responsible for motion detection and ostensibly involved in motion sickness, has been shown to be decreased in non-right-handers. It is not known if the anomalous organization of the vestibular or magnocellular systems in non-right-handers might alter susceptibility to motion sickness. Undergraduate college students completed online versions of the Edinburgh Handedness Inventory (Oldfield, Neuropsychologia 9:97–113, 1971) and Motion Sickness Susceptibility Questionnaire – Short Form (Golding, Personality and Individual Differences 41:237–48, 2006). Data from 664 undergraduate men and women revealed no support for individual differences in handedness effects on self-reported propensity to experience motion sickness in either childhood or adulthood. Findings replicate previous work of increased motion sickness in women, compared with men. Men reported being less motion sick in adulthood compared to childhood, while women reported no differences in motion sickness between childhood and adulthood. Handedness results are discussed in the context of reported individual differences in handedness effects on memory, and gender effects in terms of social desirability. Given that the handedness groups demonstrate differences in brain organization, the null effects here may shed light on the neural mechanisms that are involved in motion sickness

Hemispheric bases for emotion and memory

The goal of this Research Topic was to bring together diverse scientific perspectives on lateralized brain mechanisms underlying emotion, motivation, and memory. The Topic resulted in eight articles, three of which report original research and five of which review and synthesize past research with the aim of developing new hypotheses and theory. A range of international experts with diverse backgrounds, theoretical perspectives, and experimental methods contributed to the Topic. Contributions strongly reflect this diversity, ranging from examining pupil dilation in response to viewing Rembrandt portraits to understanding how caffeine supplementation influences levels of spatial processing. In all cases, the authors developed strong, empirically guided insights into the lateralized brain mechanisms underlying behavioral effects. Two primary themes emerge to guide and constrain continuing research

Hemispheric bases for emotion and memory

The goal of this Research Topic was to bring together diverse scientific perspectives on lateralized brain mechanisms underlying emotion, motivation, and memory. The Topic resulted in eight articles, three of which report original research and five of which review and synthesize past research with the aim of developing new hypotheses and theory. A range of international experts with diverse backgrounds, theoretical perspectives, and experimental methods contributed to the Topic. Contributions strongly reflect this diversity, ranging from examining pupil dilation in response to viewing Rembrandt portraits to understanding how caffeine supplementation influences levels of spatial processing. In all cases, the authors developed strong, empirically guided insights into the lateralized brain mechanisms underlying behavioral effects. Two primary themes emerge to guide and constrain continuing research

Strength, But Not Direction, of Handedness Is Related to Height

Left-handers are reputed to be shorter than right-handers. However, previous research has confounded handedness direction (left- versus right-handedness) with handedness strength (consistency with which one hand is chosen across a variety of tasks; consistent- versus inconsistent-handedness). Here, we support a relationship between handedness strength, but not direction, and stature, with increasing inconsistent-handedness associated with increasing self-reported height

Asymmetry in Resting Alpha Activity: Effects of Handedness

Frontal electroencephalographic (EEG) alpha band power during rest shows increased right, and/or decreased left, hemisphere activity under conditions of state or trait withdrawal-associated effect. Non-right-handers (NRH) are more likely to have mental illnesses and dispositions that involve such withdrawal-related effect. The aim of the study was to examine whether NRH might be characterized by increased right, relative to left, hemisphere activity during rest. Methods: The present research investigated that hypothesis by examining resting EEG alpha power in consistently-right-handed (CRH) and NRH individuals. Results: In support of the hypothesis, NRH demonstrated decreased right hemisphere alpha power, and therefore increased right hemisphere activity, during rest, compared to CRH.Conclusions: The study demonstrates further support for an association between increased right hemisphere activity and negative affect via an association between such EEG activity and NRH

A combined fMRI and DTI examination of functional language lateralization and arcuate fasciculus structure: Effects of degree versus direction of hand preference Author links open overlay panel

The present study examined the relationship between hand preference degree and direction, functional language lateralization in Broca’s and Wernicke’s areas, and structural measures of the arcuate fasciculus. Results revealed an effect of degree of hand preference on arcuate fasciculus structure, such that consistently-handed individuals, regardless of the direction of hand preference, demonstrated the most asymmetric arcuate fasciculus, with larger left versus right arcuate, as measured by DTI. Functional language lateralization in Wernicke’s area, measured via fMRI, was related to arcuate fasciculus volume in consistent-left-handers only, and only in people who were not right hemisphere lateralized for language; given the small sample size for this finding, the future investigation is warranted. Results suggest handedness degree may be an important variable to investigate in the context of neuroanatomical asymmetries