Cerebral Asymmetry: A Quantitative, Multifactorial, and Plastic Brain Phenotype

Abstract

The longitudinal fissure separates the human brain into two hemispheres that remain connected through the corpus callosum. The left and the right halves of the brain resemble each other, and almost every structure present in one side has an equivalent structure in the other. Despite this exceptional correspondence, the two hemispheres also display important anatomical differences and there is marked lateralization of certain cognitive and motor functions such as language and handedness. However, the mechanisms that underlie the establishment of these hemispheric specializations, as well as their physiological and behavioral implications, remain largely unknown. Thanks to recent advances in neuroimaging, a series of studies documenting variation in symmetry and asymmetry as a function of age, gender, brain region, and pathological state, have been published in the past decade. Here, we review evidence of normal and atypical cerebral asymmetry, and the factors that influence it at the macrostructural level. Given the prominent role that cerebral asymmetry plays in the organization of the brain, and its possible implication in neurodevelopmental and psychiatric conditions, further research in this area is anticipated.

Brain volume in male patients with recent onset schizophrenia with and without cannabis use disorders

“…[31][32][33] While cortical surface area seems to develop according to a fixed maturation course, 34 cortical thickness is also influenced by ex ternal factors, such as substance use. 32,35 In addition, there is a reduced cortical cerebral asymmetry in patients with schizo phrenia, 9 which can also be influenced by substance use, as there is decreased cortical thickness and altered thickness asymmetry in individuals with cocaine dependence. 35 The aim of the present study was 2fold.…”

“…32,35 In addition, there is a reduced cortical cerebral asymmetry in patients with schizo phrenia, 9 which can also be influenced by substance use, as there is decreased cortical thickness and altered thickness asymmetry in individuals with cocaine dependence. 35 The aim of the present study was 2fold. First, we sought to identify differences in brain volume, cortical thickness, cortical surface area and cortical symmetry in a large and relatively homogeneous group of male patients with recent onset schizophrenia with and without comorbid CUDs and a group of matched healthy controls.…”

Genome-wide association study of handedness excludes simple genetic models

“…The detailed relationships between neural function and brain structure are also clearly asymmetrical, reflected in laterality of modular brain functions, and (in most individuals) in strong laterality preferences for fine hand movements and other complex motor functions (Rentería, 2012;Bishop, 2013). Handedness may result in part from learning, but most evidence has supported an innate and possibly even prenatal origin (Hepper et al, 1998); co-occurrence of handedness in families suggested that handedness may be genetically determined, and some of the earliest models involve relatively simple mechanisms.…”

Left–Right Asymmetry of Maturation Rates in Human Embryonic Neural Development

“…Identifying genes involved in brain asymmetry is important because it can shed light on developmental processes that fine-tune neural circuits for their high-level functions (2,3) and because various psychiatric and cognitive disorders can involve alterations of brain asymmetries (4,5). At 8 weeks postconception, or roughly embryonic Carnegie stage (CS) 23, 85% of fetuses move their right arms more than their left arms, a proportion strikingly similar to the adult rate of right handedness (6).…”