NGF and amyotrophic lateral sclerosis: Interestingly, it is well known that extraocular motoneurons are much less vulnerable than other brainstem and spinal motoneurons to degenerating motoneuron diseases such as ALS [79,116,117,118], and spinal motoneurons that survive ALS in human patients have shown an increased TrkA expression, suggesting that NGF may provide trophic support to surviving motoneurons in this disease [119].