The Properties of Cortico-motoneuronal Connections and Their Evolutionary Significance for Amyotrophic Lateral Sclerosis

Abstract

Abstract The evolutionary significance of amyotrophic lateral sclerosis (ALS) is apparent from the fact that it is a uniquely human disease. It is a disorder affecting both descending corticospinal projections and the motoneurons which they influence. Direct, cortico-motoneuronal projections from the motor cortex to the cranial and spinal motoneurons are a subdivision of the primate corticofugal and corticospinal systems and have been strongly implicated in ALS. This chapter will review the key structural and functional properties of the cortico-motoneuronal system, emphasizing the late evolutionary development of this system and its unique importance for human motor skills such as gesture and tool manufacture and tool usage. Studying the vulnerability of the cortico-motoneuronal system to ALS might help in understanding and even treating this devastating disease.