Before revision:  We discuss well-established research and recent methodological trends motivated by experimentally observed lifelong learning factors in biological systems . Such factors include principles of neurosynaptic stability-plasticity, critical developmental stages , intrinsically motivated exploration, transfer learning, and crossmodal integration .
After revision:  We discuss well-established research and recent methodological trends motivated by experimentally observed lifelong learning factors in biological systems such as neurosynaptic plasticity, multi-task transfer learning , intrinsically motivated exploration, transfer learning, and crossmodal integration .