Hammers and Distributed Memory

In “The Feeling of what Happens” (1999), Antonio Damasio describes, among many other things, the distributed nature of memory. The following quote describes an example of how the concept of an object (in this case a hammer) may be represented in the brain (from page 220 of the book):

The brain forms memories in a highly distributed manner. Take, for instance, the memory of a hammer. There is no single place of our brain where we will find an entry with the word hammer followed by a neat dictionary definition of what a hammer is. Instead, as current evidence suggests, there are a number of records in our brain that correspond to different aspects of our past interaction with hammers: their shape, the typical movement with which we use them, the hand shape and the hand motion required to manipulate the hammer, the result of the action, the word that designates it in whatever many languages we know. These records are dormant, dispositional, and implicit, and they are based on separate neural sites located in separate high-order cortices. The separation is imposed by the design of the brain and by the physical nature of our environment. Appreciating the shape of a hammer visually is different from appreciating its shape by touch; the pattern we use to move the hammer cannot be stored in the same cortex that stores the pattern of its movement as we see it; the phonemes with which we make the word hammer cannot be stored in the same place, either. The spatial separation of the records poses no problem, as it turns out, because when all the records are made explicit in image form they are exhibited in only a few sites and are coordinated in time in such a fashion that all the recorded components appear seamlessly integrated.

If I give you the word hammer and ask you to tell me what hammer means, you come up with a workable definition of the thing, without any difficulty, in no time at all. One basis for the definition is the rapid deployment of a number of explicit mental patterns concerning these varied aspects. Although the memory of separate aspects of our interaction with hammers are kept in separate parts of the brain, in dormant fashion, those different parts are coordinated in terms of their circuitries such that the dormant and implicit records can be turned into explicit albeit sketchy images, rapidly and in close temporal proximity. The availability of all those images allows us, in turn, to create a verbal description of the entity and that serves as a base for the definition.

This 'story' of the recall of an abstract concept (by which I mean something which is not explicitly tied to a particular sensory experience) describes a situation where memory, as is generally thought of (recalling objects and events), is fully distributed throughout the brain, and can not be localised in a particular region. This concept has had much supporting empirical evidence found in recent years, including that I've reviewed in last weeks series of posts (which I believe was first proposed by Lashley in the early 20th century).