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4.6: Cerebral Lateralization

  • Page ID
    139781
    • Todd LaMarr
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    The second year of life marks a period of dramatic advances in childrens’ expressive and receptive language abilities. How does the developing brain support this explosive language growth? Cerebral lateralization refers to the functional specialization of the two cerebral hemispheres. In other words, each hemisphere becomes dominant in primarily processing specific types of information. A common example of cerebral lateralization is language processing. Most adults predominantly process language in the left hemisphere (Lust et al., 2011; Whitehouse & Bishop, 2009); however, lateralization of language to the left hemisphere is not present at birth, but rather develops over the first three years. [1]

    Across the first three years of life, neuroscience has discovered changes in brain activity, especially shifts in cerebral specialization, related to children’s language experience. As Figure \(\PageIndex{1}\) shows, between 13 to 17 months of age, brain activity is bilateral (activated across both hemispheres). However, just a few months later, by 20 months of age, brain activity is predominantly lateralized to the left hemisphere (Mills, Coffey‐Corina & Neville, 1997: Mills et al., 2004). This pattern of results has been supported by studies of word processing in 19 to 22-month-old simultaneous bilingual children (Conboy and Mills, 2006), in late talkers up to age 30 months (Mills et al., 2005a), and in 18 to 30-month-old children with autism spectrum disorder and typically developing controls (Kuhl et al., 2013). These data indicate that left lateralization of brain activity is not present at birth and the timing from bilateral to left lateralization is strongly related to experience with language, specifically word familiarity, rather than chronological age (Mills et al., 2005). [2]

    Activation in both hemispheres. Differences between familiar and unfamiliar words emerged by 150 ms and are sustained across the entire episode. Region Right IFC	Window 150–300 ms	Βa0.51	(95 % CI) (0.24, 0.78)	P 0.001 Region Left IFC	Window 150–300 ms	Βa0.10	(95 % CI) (−0.26, 0.46)	P 0.56
    Figure \(\PageIndex{1}\): Activation in both the left and right hemispheres of the inferior frontal cortex of 14-month-old children listening to familiar and unfamiliar words. Shaded areas reflect significant differences between familiar (blue line) and unfamiliar (red line) words. ( [3])

    [1] Groen et al., (2012). Does cerebral lateralization develop? A study using functional transcranial Doppler ultrasound assessing lateralization for language production and visuospatial memory. Brain and Behavior, 2(3), 256-269. CC by NC 3.0

    [2] Bosseler et al., (2021). Using magnetoencephalography to examine word recognition, lateralization, and future language skills in 14-month-old infants. Developmental Cognitive Neuroscience, 47, 100901. CC by 4.0

    [3] Image from Bosseler et al., (2021). Using magnetoencephalography to examine word recognition, lateralization, and future language skills in 14-month-old infants. Developmental Cognitive Neuroscience, 47, 100901. CC by 4.0


    This page titled 4.6: Cerebral Lateralization is shared under a mixed 4.0 license and was authored, remixed, and/or curated by Todd LaMarr.