, 2008, Teramitsu et al., 2010 and Teramitsu and White, 2006). During song development, FoxP2 knockdown in Area MG-132 supplier X by lentivirus-mediated RNA interference causes inaccurate song imitation and a reduction in neural spine density ( Haesler et al., 2007). Thus, the thalamocortical–basal ganglia circuit is thought to contribute during development to song learning and vocal control in songbirds, with FoxP2 intimately involved, similar to the situation in humans ( Haesler et al., 2007, Schulz et al., 2010 and Teramitsu et al., 2010). Overall, these results suggest that the FoxP2 expression pattern in the thalamocortical–basal

ganglia circuit is conserved between marmoset and other species. The IO is important for learning and timing of motor control ( De Zeeuw et al., 1998), and is closely associated with the cerebellum. Jurgens and Richter (1986) reported that vocalizations can be induced by electrically stimulating the IO ( Jurgens & Richter, 1986). Therefore, although the relationship between the IO and

speech is unclear, it may be associated with vocalization in humans. Future studies are necessary to investigate the role of the IO and speech disorder-related genes in vocalization. Almost all speech impairments and reading disabilities are Buparlisib nmr learning disorders, prevalent in childhood. Most of the genes associated with these disorders play important roles in neural development, yet show different expression Celecoxib patterns in different brain areas. Furthermore, expression levels or patterns of these genes also changed during development in the marmoset brain (Table 2). Non-human primates do not have language or acquire

vocalization in the way that humans do, because of differing neuroanatomical connectivity of the auditory–vocal regions between humans and non-human primates. The arcuate fasciculus is a white-matter fiber tract that links the lateral temporal cortex with the frontal cortex, via a dorsal projection that arches around the Sylvian fissure (Rilling et al., 2008). The arcuate fasciculus shows significant differences between human and monkey brain, with projections to the middle and inferior temporal gyrus absent in monkey (Thiebaut de Schotten, Dell’Acqua, Valabregue, & Catani, 2012). In addition, from the point of view of vocal learning, direct connections between the telencephalon and medullary vocal motor nucleus have been reported in a limited number of vertebrates. In mammals, direct connections between the primary motor cortex and nucleus ambiguus that controls the vocal organ, are present in humans (Iwatsubo et al., 1990, Kuypers, 1958a and Schoen, 1969), but not observed in monkeys (Jurgens, 1976, Jurgens, 2002, Kuypers, 1958b and Simonyan and Jurgens, 2002). In contrast, neural activation in the homologue of Broca’s area is observed in vocalizing marmosets using gene expression analysis of immediate early genes (Simoes et al., 2010).