A"brain cramp" is when you can't think of something like a name), "je cale", "j'ai un trou de mémoire; a "senior moment" (see Golf Brooks's hilarious song "Senior Moments...Brain Farts") is when you can't remember why you've come into a room, for instance - the type of incident that makes you aware you're aging and, if it begins to happen fairly frequently, makes you wonder if it's the onset of Alzheimer's. For "brain cramp", I sometimes say "My neurons misfired" ("J'ai une panne de neurones"), as I mentioned in a much earlier diferent thread.