Article

Two distinct forms of functional lateralization in the human brain

Section on Cognitive Neuropsychology, Laboratory of Brain and Cognition, and Scientific and Statistical Computing Core, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 08/2013; 110(36). DOI: 10.1073/pnas.1302581110
Source: PubMed

ABSTRACT The hemispheric lateralization of certain faculties in the human brain has long been held to be beneficial for functioning. However, quantitative relationships between the degree of lateralization in particular brain regions and the level of functioning have yet to be established. Here we demonstrate that two distinct forms of functional lateralization are present in the left vs. the right cerebral hemisphere, with the left hemisphere showing a preference to interact more exclusively with itself, particularly for cortical regions involved in language and fine motor coordination. In contrast, right-hemisphere cortical regions involved in visuospatial and attentional processing interact in a more integrative fashion with both hemispheres. The degree of lateralization present in these distinct systems selectively predicted behavioral measures of verbal and visuospatial ability, providing direct evidence that lateralization is associated with enhanced cognitive ability.

3 Followers
 · 
288 Views
  • Source
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: One of the most robust and oft-replicated findings in cognitive neuroscience is that several spatially distinct, functionally dissociable ventral occipitotemporal cortex (VOTC) regions respond preferentially to different categories of concrete entities. However, the determinants of this category-related organization remain to be fully determined. One recent proposal is that privileged connectivity of these VOTC regions with other regions that store and/or process category-relevant properties may be a major contributing factor. To test this hypothesis, we used a multicategory functional magnetic resonance imaging (MRI) localizer to individually define category-related brain regions of interest (ROIs) in a large group of subjects (n = 33). We then used these ROIs in resting-state functional connectivity MRI analyses to explore spontaneous functional connectivity among these regions. We demonstrate that during rest, distinct category-preferential VOTC regions show differentially stronger functional connectivity with other regions that have congruent category-preference, as defined by the functional localizer. Importantly, a “tool”-preferential region in the left medial fusiform gyrus showed differentially stronger functional connectivity with other left lateralized cortical regions associated with perceiving and knowing about common tools—posterior middle temporal gyrus (involved in perception of nonbiological motion), lateral parietal cortex (critical for reaching, grasping, manipulating), and ventral premotor cortex (involved in storing/executing motor programs)—relative to other category-related regions in VOTC of both the right and left hemisphere. Our findings support the claim that privileged connectivity with other cortical regions that store and/or process category-relevant properties constrains the category-related organization of VOTC. Hum Brain Mapp, 2015. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.
    Human Brain Mapping 02/2015; 36(6). DOI:10.1002/hbm.22764 · 6.92 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Sequence learning relies on formation of unconscious transitional and conscious ordinal memories. The influence of practice type on formation of these memories that compose skill and systems-level neural substrates are not known. Here, we studied learning of transitional and ordinal memories in subjects trained on motor sequences while scanned using fMRI. Practice structure was varied or grouped (mixing or grouping sequences during training respectively). Memory was assessed 30mins and one-week later. Varied practice improved transitional memory, enhanced coupling of the dorsal premotor cortex with thalamus, cerebellum, lingual and cingulate regions, and greater transitional memory correlated with this coupling. Thus, varied practice improves unconscious transitional memories in proportion to coupling within a cortico-subcortical network linked to premotor cortex. This result indicates practice structure influences unconscious transitional memory formation and identifies underlying systems-level mechanisms.
    Journal of Cognitive Neuroscience 02/2015; DOI:10.1162/jocn_a_00796 · 4.69 Impact Factor