Hemispheric Asymmetries: The Comparative View

Abstract

Hemispheric asymmetries play an important role in almost all cognitive functions. For more than a century, they were considered to be uniquely human but now an increasing number of findings in all vertebrate classes make it likely that we inherited our asymmetries from common ancestors. Thus, studying animal models could provide unique insights into the mechanisms of lateralization. We outline three such avenues of research by providing an overview of experiments on left–right differences in the connectivity of sensory systems, the embryonic determinants of brain asymmetries, and the genetics of lateralization. All these lines of studies could provide a wealth of insights into our own asymmetries that should and will be exploited by future analyses.

Right ear advantage for vocal communication in frogs results from both structural asymmetry and attention modulation

“…Interestingly, communication asymmetry has been reported in bats at the level of single cortical neurons, with left-hemispheric neuronal advantage for processing social calls and right-hemispheric neuronal advantage in processing navigational signals [24]. These findings including the present results suggest a phylogenetically early emergence of vocal communication asymmetries [4]. Accordingly, language lateralization in humans may reflect a more primitive left-hemispheric dominance for processing basic features of species-typical sounds [16] in which temporal features might be determinant auditory cues for call recognition.…”

“…lateralization or asymmetry of brain function, has been described in many vertebrate taxa including fish, frogs, reptiles, birds and mammals [1][2][3], as a fundamental aspect of nervous system organization [4]. The left hemisphere is specialized to categorize information and responds to features that are invariant and repeated, while the right domestic horses [18] and rhesus macaques [19].…”

Gene(s) and individual feeding behavior: Exploring eco‐evolutionary dynamics underlying left‐right asymmetry in the scale‐eating cichlid fishPerissodus microlepis

“…A similar complex architecture has been reported in human and other fish handedness and brain lateralization (reviewed in Ocklenburg & Gunturkun, 2012). …”

Components of the Language-Ready Brain

“…I agree with Ocklenburg and Güntürkün (2012) (Hynd et al, 1995), white matter constitutes a perfect mirror candidate of the developmental nature of human language acquisition. Besides, as I noted above, the chemical mechanisms of myelination are decisive for axons' generating action potentials, something that can be directly associated with the oscillatory basis of language I will shortly highlight.…”

“…Comparative studies have suggested a left-hemispheric dominance for conspecific communication in a wide variety of species (Ocklenburg and Güntürkün, 2012), such as chimpanzees (Taglialatela et al, 2008), rhesus monkeys (Hauser and Andersson, 1994), dogs (Siniscalchi et al, 2008), mice (Ehret, 1987), sea lions (Böye et al, 2005), and frogs (Bauer, 1993). More tellingly, a left-dominance has been reported in canaries as regards to hypoglossal functions (Nottebohm, 1971), in zebra finches concerning vocal learning (Voss et al, 2007; and in Bengalese finches for song discrimination (Okanoya et al, 2001).…”