hallervorden-spatz syndrome is a disorder characterized by dystonia, parkinsonism, and iron accumulation in the brain. the disease is caused by mutations in gene encoding pantothenate kinase 2 (pank2) and patients have pantothenate kinase-associated neurodegeneration. we present an 8-year-old boy with progressive muscle dystonia, neuroregression, frequent fall and multiple injury marks of diffe...

The contributions to this special issue on cognitive development collectively propose ways in which learning involves developing constraints that shape subsequent learning. A learning system must be constrained to learn efficiently, but some of these constraints are themselves learnable. To know how something will behave, a learner must know what kind of thing it is. While this has led previous...