This matter of losing a common word and replacing with an uncommon or arcane synonym or close synonym: it suggests that it’s not a simple matter of loss of meaning. Clearly, the meaning is present, perfectly: I couldn’t remember “birdwatcher” but said “ornithologist” without a beat missed; I couldn’t bring up “actor” but said “thespian” despite with some distaste.
If the meaning is completely present, why would the common word be unavailable [rather] than the arcane word? I can only speculate that it’s not memory that’s the problem — besides, these common words eventually come back to me, so they must already be in memory — it must be a break in the retrieval link, as if the link is haywire, and once off-track, it’s left to tip-of-the-tongue branching down the wrong line route towards the bridge to nowhere.
Could the word-chooser linked wrong to a phonetic element? Or to an agentive/object confusion? Or is there just a broken link to too far down the access to the common word?
In other words, is there a) a mistaken link or is there b) a broken or failed link?
Broken or failed link suggests a dynamic of mere missing connections, either because some cell is not working or not connecting right. Mistaken link suggests more possibilities, I think. The connections could be failing while other pathways are compensating, sometimes wrongly. Or connections are rewired badly. What other possibilities? Could it be that the grammar module, failing at the interaction with the lexicon, the retrieval of the lexical item is broken, so the meaning function has to go back up to other alternative lexical items? But why can’t the meaning function able to back track to find the common word? Why is it easier to find an arcane word? It’s as if tip-of-the-tongue, once occurred, becomes a stubborn mislink.
aphasic diary 
January 20, 2010 at 12:15 am |
I think you are perfectly correct to say that the memory for all the words are intact, since you remember the word later. It is the link to the word that is weak. Sometimes it works, sometimes it doesn’t. Also, in conversation, the retrieval has to be very rapid, and that can be a problem. Perhaps when you have more time to recall the word (as when you are writing), recall is more accurate.
You mentioned that there seemed to be more difficulty with compound words, such as bird watcher and men’s shelter. Perhaps this indicates that these forms are stored differently than single words, and that for some reason, it is harder for you to access these types of words.
Another good question is why sometimes the wrong word is retrieved. One concept that I remember from neural networks theory is that a concept is activated by the convergence of inputs from a variety of sources. If there is an interruption in some of the inputs, then an unbalanced pattern of excitation is set up, and the wrong word could be activated.
It is a bit mysterious why the more common word was not activated. Usually we conceptualize that the pathway to the more common word is stronger. However, in this case, there was obviously some kind of block to the more common word, so as an alternative, a less common word was chosen.
Perseveration is persistence in following the same track, even if it is not correct, and difficulty in “switching gears”. The more similar two tasks are, the easier it is to perseverate. Usually a complete change in the type of task with “break up” the perseveration. For example, if I am talking to a patient who is perseverating, I will say, “Look out the window!” This change in focus to a completely different task “resets” the mechanism. Perseveration seems to be most common immediately after a stroke, and decreases over time. Perhaps it takes time for the brain to regenerate flexible pathways.
It is great that the walking tour went well, even if your language was occasionally “high flown”!