A team of researchers led by Professor Emeritus Toshiya Matsushima at Hokkaido University has found an ASD-like behavioral impairment in chicks, suggesting a molecular pathway of ASD pathogenesis. Their results were published in the online journal Cerebral Cortex Communications.

One of the earliest indications of ASD is a retarded preference for animate objects such as face configuration and biological motion (BM). This preference typically appears in neonates (newborns), but it is hampered in individuals with familial ASD risk. Common mammalian model animals such as rats and mice are not valid for studying this aspect of ASD as they do not spontaneously exhibit BM preference.

The team used chicks as a model to study BM preference. Similar to humans, chicks exhibit a preference for BM very early in life, concomitant with social attachment formation by imprinting. Although birds and mammals diverged some 300 million years ago, some of their visual and motor control systems are conserved despite the evolutionary distance.

The authors initially hypothesized that spontaneous movement of fetuses is critical for the BM preference to develop. To test this, they injected fertilized eggs with ASD-risk chemicals while "listening" to the fetal movements through a record stylus gently placed on the shell surface. After hatching, preference of the chicks was tested in a T-shaped maze.