If he is sending you to a 4 hour NeuroCog testing, it sounds like it may be a NeuroPsychological Assessment. A Neuro Psych Assessment is the best way to identify your struggles. I've had 3 full NPAs and one shortened NPA.

Has he told you who or what clinic will do the testing ?

There is no way to prepare for the testing. Just show up as if it is just another day.

Some more basic NeuroCog testing is done with computer tests with just some tests administered by the tester.

It usually takes a few weeks to get the report of the results. They may show speed of processing, executive functioning, memory functions, and a number of other factors. It depends on what battery of tests are done. It is not one test. It is multiple shorter tests.

If you do the brain exercises, keep in mind that they are exercise, not intense effort. Brain challenges are often too intense. You do not want to get frustrated and sense failure. In fact, you want just the opposite. You want to do tasks where you will be successful most of the time.

I did a lot of Windows Solitaire, Spider Solitaire (intermediate, two suits), FreeCell, Minesweeper, and such. They are included with most versions of Windows. There are downloadable versions also available. You can do them as fast as you like. They exercise multi-step processing.

I do a lot of computer based jig saw puzzles.

Jigsaw - MSN Games - Free Online Games
I use the edges function then the arrange function so I don't have to sort the pieces. I shoot for 7 minutes but different puzzles can take up to 20 minutes. I do 3 every day.

and Free Jigsaw Puzzles - Jigsaw Puzzle Games at TheJigsawPuzzles.com - Play Free Online Jigsaw Puzzles I choose the 100 piece puzzles.

Also, Scrabble known as Just Words Play Just Words Online - AOL Games You can set the difficulty so the computer plays at your level.

Crosswords can be a challenge if you are struggling with word finding. I don't push with crossword puzzles. Scrabble/Just Words is better in my view.