How do Brains Imagine?

Cognitive scientists hypothesize that our ability to imagine is the result of something called a “mental workplace,” a neural network that coordinates activity across multiple regions of the brain.

Discussing his latest research, neuroscientist Alex Schlegel explores this in its relation to consciousness and the future of ‘fathoming the mind’.

Question: What do you understand by the word ‘Imagination’?

I think of imagination as a flexible, creative, playful process in which we recall things we have experienced or learned in the past and reshape them into new possibilities, ideas, concepts, theories, art works, etc.  Note that imagination doesn’t need to be visual.  Probably through lack of imagination, we tend to use the single term “imagery” for all sorts of both visual and non-visual internally driven experiences.

Question: Cognitive scientists hypothesize that our ability to imagine, to come up with mental images and creative new ideas, is the result of what they call a ‘mental workspace’. What is the ‘mental workspace’?

The idea of a mental workspace grew out of one theory about how consciousness works.  There are (at least) two opposing views of consciousness.  One view advanced by Semir Zeki and others states that conscious experience arises in any area of the brain that makes information explicit.  For instance, according to this theory the neural correlates of the conscious experience of color are the areas of visual cortex that first represent information about color.  The experience of motion, on the other hand, arises in the parts of visual cortex that process information about motion.  A contrasting view, dubbed Global Workspace Theory and advanced by scholars such as Bernard Baars and Stanislas Dehaene, suggests instead that conscious experience occurs not wherever information is first made explicit or represented, but rather after that information is transferred to some kind of mental space that can access and manipulate information from all over the brain in a common format.

Regardless of its relationship to consciousness, this mental workspace appears to be highly developed in humans.  Within our own internal mental world, we humans can mull over past experiences and reshape them into new ideas, plans, and possible futures.  As neuroscientists we still have very basic questions about how this system works.  Which brain areas are involved in the mental workspace and how do they communicate with each other?  Are a fixed set of areas responsible for the mental workspace, or can the neural structures that compose it change depending on the task at hand (for instance, recruiting the auditory cortex if we are composing a piece of music, or visual cortex if we are imagining the layout of this year’s garden).

Question: Imagery is defined as the production of mental images associated with previous percepts, and imagination as the faculty of forming mental images of a novel character relating to something that has never been actually experienced by the subject (something that emerges from a person’s inner world). A number of neuroscientists have proposed that imagination is the result of a “tinkering” that combines and modifies stored perceptual information and concepts, leading to the creation of novel “mental objects” that are shaped by the subject peculiar inner world (related to a person’s self-awareness).  Do you agree with this hypothesis, and, if not, why not?

That all sounds reasonable.  What would the alternative to this hypothesis be?  That the imagination can create concepts with absolutely no basis in previously stored information?  To me, the beauty of imagination is not that it is unconstrained by past experience, but that it is free to reshape past experiences in new ways.

Question: Your study focused on visual forms of imagination. Are you planning research that looks at other forms, for instance, conceptual and intellectual, or the imagination that creates stories or is involved in memory retrieval?

One idea we are testing is whether the mental workspace can be thought of as a core of functionality that recruits specialized subsystems for tasks as needed.  Our study involved the manipulation of visual imagery, so in this case you could think of the visual cortex in the occipital lobe as being such an example of a specialized subsystem.  If we did another experiment involving manipulations of auditory imagery, would we find auditory cortex recruited instead?  If so, how does this core work?  How does it make all of these domain-specific systems do its bidding?

I am definitely interested in studying imagination in all its forms.  However, we need to be careful not to assume that our concepts about cognitive processes map cleanly onto what is going on in the brain.  The concept of “attention” is a good case in point.  For a long time, attention was thought of as a unitary control mechanism that directed how the brain would allocate its limited processing resources.  We now know that attention actually takes many forms, and thus several independent brain areas are responsible for directing it.  For instance, exogenous or bottom-up attention tells the brain to direct processing resources to important external stimuli, like that tiger running at you from the left.  Contrast this with endogenous or top-down attention, which is what happens when you scan visually through that thicket over there to find the tiger lurking in the shadows and waiting to pounce.  As we better understand the brain, we are finding it necessary to rethink attention and many other concepts such as the self, the mind, and consciousness itself.

In that light, I suspect that many forms of imagination may arise out of the same general neural machinery.  We have to let our findings about the brain shape our concepts as much as we let our existing concepts direct the questions we ask about the brain.

Question: What, in your view, makes some people more creative (or imaginative) than others?

There are probably far more factors that influence creativity than I can discuss in a single response!  However, my general inclination is that the results of our creative or imaginative efforts are more a product of what we put our minds to, i.e. what we believe is possible and how determined we are to make those possibilities happen, than they are the products of innate and unchangeable abilities.  We are working on publishing the results of a study that found art students becoming more creative thinkers as they studied, and that these improvements in creativity were associated with changes in the structural organization of the brain.  So it appears that creativity can definitely be cultivated.  Why some people feel more inclined to cultivate those abilities than others, though, is a complex question indeed!


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