I think neurological motivation isn't quite like the classical use of the word motivation, but is more a composite of understanding problems and approving outcomes. If you expect the reward to be dissatisfactory it won't trigger all the proper neurological response, or problems within the brain won't produce expected motivational behavior.
I currently do not think this is a good explanation, at least with respect to executive function in ME. I would argue that, in my experience and that of others I have discussed this with, we understand and consider things desirable, we just cannot go there. In my case I can break a problem down into nice easy steps, with a step by step plan to achieve my goals. Then I go to do the very first thing, something easy ... no idea how to do it! This is not with everything, or all the time, just generally the case, and much worse when I am sleep deprived or in a crash.
There are also holes in my cognition, like today I could not deal with plastic bags, they are amorphous monstrosities from the Twilight Zone. I picked one up, and consistently held it the wrong way, dropping the rubbish to the floor. In the past I have had a big issue figuring out where the opening is ... my three techniques to open an open plastic bag are to rip a hole, pick it up and shake it till something falls out, or to use tactile discovery and keep feeling around the bag till I find the hole. This is about visual spatial reasoning ... there is a big fail in my cognition somewhere.
Similar issues occur with numbers. I have tutored university level math. At my very bad days, not bad enough I lose language, but bad, I cannot count to three. Most things involving numbers are really, really difficult. Yet I still grasp relationships, trends etc. The concepts are there, its the numbers I have issues with. I can do some things with numbers only if I treat them as letters, and do pattern matching. This is one of the reasons I am less engaged with science these days ... science and numbers go together.
My point is that cognition is a complex mix of many different capacities, and if one or more from that mix of capacities is broken then the complex outcomes are flawed.