To represent the action Put the apple in the pail, the Origin pronome must be assigned to an apple-neme, and the Destination pronome to a polyneme for pail. However, at another time, another process might need the Origin to represent a block and the Destination to represent a tower top. Each pronome must be assigned to different things at different times, and only for long enough to complete the task of the moment. In other words, a pronome is a type of short-term memory.
This suggests a simple way to embody the idea of a pronome: each pronome is simply a temporary K-line. The basic difference, then, between a pronome and a K-line is that a pronome's connections are temporary rather than permanent. We can assign a pronome by temporarily connecting it to whichever currently active agents it reaches. Then, when we activate that pronome again, those same agents will be aroused. To make the Origin pronome represent an apple, first activate an apple-neme; this will arouse certain agents.
Next, quickly assign the Origin pronome. Those agents will then become attached to that pronome and presumably remain attached until the pronome is reassigned.
If we compare pronomes and polynemes from this point of view, we see that they are closely related.
Polynemes are permanent K-lines. They are long-term memories. Pronomes are temporary K-lines. They are short-term memories.
It is not yet known today how brains form long-term memories. One hypothesis would be that we don't really have temporary K-lines at all, but that after a pronome's K-line is used, it becomes permanent, and the pronome machinery gets connected to another, previously unused K-line. However this works, we know little about it except that it requires a substantial amount of time to form a permanent memory — a time on the order of half an hour. If there is any serious disturbance in that interval, no memory will be formed. There also is some evidence that we can form new long-term memories at rates on the order of no more than perhaps one every few seconds, but this is very imprecise because we have no good definition of what we mean by separate memories. In any case, this seems to suggest that we might have several hundred such processes going on at once.
Why does the process take so long? Perhaps because it simply takes that long to synthesize chemicals used to make permanent connection bridges between agents. Perhaps most of that time is consumed in searching for an unused K-line agent, particularly for one that already has the required potential connections. Or perhaps the required connections could emerge from distributed memories like those we mentioned briefly in section 20.9.