Hemispheric lateralization in reasoning

Abstract

A growing body of evidence suggests that reasoning in humans relies on a number of related processes whose neural loci are largely lateralized to one hemisphere or the other. A recent review of this evidence concluded that the patterns of lateralization observed are organized according to two complementary tendencies. The left hemisphere attempts to reduce uncertainty by drawing inferences or creating explanations, even at the cost of ignoring conflicting evidence or generating implausible explanations. Conversely, the right hemisphere aims to reduce conflict by rejecting or refining explanations that are no longer tenable in the face of new evidence. In healthy adults, the hemispheres work together to achieve a balance between certainty and consistency, and a wealth of neuropsychological research supports the notion that upsetting this balance results in various failures in reasoning, including delusions. However, support for this model from the neuroimaging literature is mixed. Here, we examine the evidence for this framework from multiple research domains, including an activation likelihood estimation analysis of functional magnetic resonance imaging studies of reasoning. Our results suggest a need to either revise this model as it applies to healthy adults or to develop better tools for assessing lateralization in these individuals.

A neural correlate for common trait dissociation: Decreased EEG connectivity is related to dissociative absorption

“…For example, left-hemispheric activity is associated with better ability to ignore irrelevant information (Ambrosini & Vallesi, 2016b) and to infer and create explanations even at the cost of ignoring conflicting evidence (Turner, Marinsek, Ryhal, & Miller, 2015). Conversely, right-hemispheric activity is associated with the ability to reduce conflict between elements to create a refined explanation when faced with new evidence (Turner et al, 2015). Possibly, in light of our findings, individuals with desynchronized left hemispheres tend to ignore peripheral information more (i.e., be oblivious to it) and integrate less.…”

Pre-trauma Methylphenidate in rats reduces PTSD-like reactions one month later

“… 40 , 41 That is, while upregulation of left-hemisphere dopaminergic function is related to task accuracy and left-PFC control over working memory (WM) processes, 42 single low doses of MPH were shown to normalize left-hemisphere dopaminergic underfunctioning in ADHD, 41 and to upregulate functional activation in left-PFC regions involved in temporal processing 43 and mediation of WM load. 40 These lateralized effects become specifically relevant given that functional lateralization is strongly related to emotional regulation 44 , 45 and memory processing 8 , 46 in healthy human populations, and the intrusive nature of traumatic recollections 47 , 48 and severity of symptoms 49 , 50 in PTSD. Moreover, while in healthy subjects successful regulation of emotional responses during aversive learning involves left-hemisphere activity increment 51 and selective left-hippocampus activation modulates the accuracy of its associative representations, 8 cued-retrieval of traumatic representations and emotional flashbacks in PTSD were found to involve selective left-hemisphere underactivation 47 , 48 (see Hughes et al 47 for a comprehensive review).…”

Mapping Cortical Brain Asymmetry in 17,141 Healthy Individuals Worldwide via the ENIGMA Consortium

“…Keywords: brain asymmetry; lateralization; cortical thickness; surface area; meta-analysis Understanding the functional specialization of the cerebral hemispheres is a long-standing and central issue in human neuroscience research. At the population-level, hemispheric asymmetry, or lateralization, is involved in various perceptual and cognitive functions, including language (1, 2), face processing (3)(4)(5), visuospatial processing (3,6,7), and reasoning (8,9), as well as handedness (10).…”

“…Understanding the functional specialization of the cerebral hemispheres is a long-standing and central issue in human neuroscience research. At the population-level, hemispheric asymmetry, or lateralization, is involved in various perceptual and cognitive functions, including language (Vigneau et al, 2006;Vigneau et al, 2011), face processing (Badzakova-Trajkov et al, 2010;Willems et al, 2010;Zhen et al, 2015), visuospatial processing (Badzakova-Trajkov et al, 2010;Zago et al, 2017;Zhen et al, 2017), and reasoning (Fornito et al, 2004;Turner et al, 2015), as well as handedness (Steinmetz et al, 1991). For example, language lateralization involves leftward dominance for various processes involved in speech perception and production in most people (Vigneau et al, 2006;Vigneau et al, 2011).…”