On this model, there are no images in the brain (or mind[1]) — there are neuronal firing patterns. But some neuronal firing patterns correlate with differentiations of the visually perceivable. The firing of such patterns correlate with experiencing the differentiation of the visible, with having visual experiences.[2] Regenerations of past firing patterns can result in visual experiences in the absence of the originally experienced perceivable. By generating portions of different past visual experiences as an integrated whole, it is possible to create new visual experiences that have not previously been experienced — to imagine. And such simulations can be expressed through the skeleto-muscular system as pictorial images that others can experience.
More generally, to be congruent[3], there are no symbols or representations (things) in brains[4]; there are cells and tissues and the functions they perform (processes). Neurological systems make symbols and representations possible, but, through skeleto-muscular action, as perceivable expressions which can be categorised and recategorised and re-expressed, and so on. Lamb (2005) has expressed this point clearly in modelling language with respect to neurological systems:
Likewise, if we consider production of speech, no one has ever found any evidence at all, neurological or otherwise, to support an hypothesis that it operates by the use of symbols represented somehow in the brain. The more realistic alternative is to suppose that what is internal is not symbolic representations of words or morphemes or the like, but the means of producing such forms (as speech or writing).
Footnotes:
[1] Sometimes the word ‘mind’ is used in these contexts rather than ‘brain’. However, since the mind is not detectable as a (material) thing, it cannot be construed congruently as a place in the material universe that science models, and it is thus incongruent to speak of ‘in the mind’. See the discussion of ‘mind-as-process’ later in the chapter.
[2] See Edelman & Tononi (2000: 202-3).
[3] Those who might claim to speaking metaphorically (eg Hofstadter, Ramachandran) do not provide a congruent reformulation.
[4] The idea that symbols exist in brains is consistent with the instructionist model and with naïve realism: the belief that the world consists of true or real categories, and these are represented (accurately or not) in brains.