Primary motor cortex asymmetry is correlated with handedness in capuchin monkeys (cebus apella).

Abstract

Humans exhibit a population-wide tendency toward right-handedness, and structural asymmetries of the primary motor cortex are associated with hand preference. Reported are similar asymmetries correlated with hand preference in a New World monkey (Cebus apella) that does not display population-level handedness. Asymmetry of central sulcus depth is significantly different between left-handed and right-handed individuals as determined by a coordinated bimanual task. Left-handed individuals have a deeper central sulcus in the contralateral hemisphere; right-handed individuals have a more symmetrical central sulcus depth. Cerebral hemispheric specialization for hand preference is not uniquely human and may be more common among primates in general.

Further evidence of an association between handedness and neuroanatomical asymmetries in the primary motor cortex of chimpanzees (Pan troglodytes)

“…Chimpanzee hand preferences correlate with the depth of the CS, particularly in the more dorsal regions of the motor cortex, a finding consistent with recent studies in humans (Amunts et al, 1996;Foundas et al, 1995) and capuchin monkeys (Phillips & Sherwood, 2005). Moreover, the strongest and most consistent association between handedness and brain asymmetry were linked to the KNOB, a region of the precentral gyrus corresponding to the hand region (at least in humans).…”

“…In squirrel monkeys, greater neural activity in the motor cortex is found in the hemisphere contralateral to the preferred hand (Nudo, Jenkins, Merzenich, Prejean, & Grenda, 1992). In capuchin monkeys, asymmetries in the dorsal portion of the precental gyrus are correlated with hand preferences for coordinated bimanual actions (Phillips & Sherwood, 2005). Similarly, in chimpanzees, hand preferences are associated with asymmetries in the "knob", a region of the precentral gyrus but not with asymmetries in either the inferior frontal gyrus or planum temporale (Hopkins & Cantalupo, 2004).…”

Exploring the relationship between cerebellar asymmetry and handedness in chimpanzees (Pan troglodytes) and capuchins (Cebus apella)

“…Together with recent studies on the relationship between handedness and areas of the primary motor cortex in chimpanzees (Dadda, Cantalupo, & Hopkins, 2006;Hopkins & Cantalupo, 2004) and capuchins (Phillips & Sherwood, 2005), these results contribute to the growing body of literature on the neurobiology of handedness. However, much remains to be addressed concerning the evolution of cerebellar specialization and its relationship to handedness.…”

“…For example, evidence from chimpanzees indicates that hand preferences for non-communicative actions are correlated with asymmetries of the KNOB, a region of the precentral gyrus, but not language area homologues (Dadda, Cantalupo, & Hopkins, 2006;Hopkins & Cantalupo, 2004). Similarly, asymmetries of the dorsal portion of the precentral gyrus are associated with hand preference in capuchin monkeys (Phillips & Sherwood, 2005). In squirrel monkeys, single cell recording studies have shown greater activity in the dorsal portion of the motor cortex in the hemisphere contralateral to the preferred hand (Nudo et al, 1992).…”

Lateralization of the Vertebrate Brain: Taking the Side of Model Systems: Figure 1.

“…Right-handed gesturing chimpanzees have a larger left inferior frontal gyrus compared with non-right-handed gesturing chimpanzees. Second, hand preferences for noncommunicative behaviors do correlate with asymmetries in the dorsal portion of the precentral gyrus, referred to as the "knob," in which neural representation of the hand is located in the primary motor cortex in both chimpanzees and capuchin monkeys (Phillips and Sherwood, 2005). Thus, different behavioral measures of hand use correlate with asymmetries from distinct regions of the frontal lobe.…”