Hypothesis on cerebral dominance

Development of infant ear asymmetries for speech and music

“…On the other hand, Leavitt et al, (1976) tested 6-week-olds in a cardiac habituation study of sound-pattern discrimination, and found evidence for earlier cortical involvement in the detection of pulsed-tone frequency contrasts than in the detection of phonetic contrasts. In line with this report of greater maturity for the early processing of nonspeech than of speech, the suggestion that the right hemisphere is more "active" than the left in early infancy (Brown & Jaffe, 1975;Crowell et aI., 1973;Taylor, 1969) would predict a music LEA to be found earlier than a speech REA, perhaps in our 2-month-olds.…”

“…Others, however, contend that while some form of lateralization is present early, asymmetries for various abilities emerge only as those abilities mature (e.g., Witelson, 1977). Alternatively, some researchers have claimed that specialized right-hemisphere functions dominate in early development (e.g., Brown {Jc, Jaffe, 1975;Crowell, Jones, Kapuniai, & Nakagawa, 1973;Taylor, 1969), or conversely that left-hemisphere specialization precedes that for the right (e.g., Corballis & Morgan, 1978). Unfortunately, extant empirical work cannot resolve the controversy, because there has been little systematic developmental research on infant cerebral asymmetries.…”

Performance of younger and older adults in lateralised right and left hemisphere asymmetry tasks supports the HAROLD model

“…In more detail, the commonly observed left face bias was indeed evident in younger men, and was in magnitude more pronounced to the one in older men, but also more pronounced to the one in younger women. Taken together, findings from both tasks would rather support the HAROLD 22 model (Cabeza, 2002) than the RHAM (Albert & Moss, 1988;Brown & Jaffe, 1975), at least when considering men's performances.…”

“…According to the RHAM (Albert & Moss, 1988;Brown & Jaffe, 1975), age-related cognitive decline should be more pronounced for functions of the right hemisphere (e.g. spatial processing, visual face processing) due to a smaller gray/white matter ratio in the right than the left hemisphere (Good et al, 2001;Gur et al, 1980;Pujol et al, 2002; but see Smeets et al, 2010).…”

“…Another explanation 4 could be that the brains of high-performing older adults compensate for age-related neural decline by means of reorganization and changes in functional connectivity between brain areas (Cabeza, Anderson, Locantore, & McIntosh, 2002), in particular within prefrontal structures (Park & Reuter-Lorenz, 2009). Two models on the cerebral markers of healthy aging have been presented with the first being the right hemi-aging model (RHAM) (Albert & Moss, 1988;Brown & Jaffe, 1975), and a later model being the Hemispheric Asymmetry Reduction in Older Adults (HAROLD) Model (Cabeza, 2002). Both models assume that the human brain compensates for age-related changes in neuronal mechanisms that affect cognitive functioning by methods of reorganization and changes on functional connectivity (see also Cabeza, 2001;Grady et al, 1994;Raz, 2000;Tsujii, Okada, & Watanabe, 2010).…”