Underlying Brain Mechanisms of Internal Knowledge Representation

What are the underlying brain mechanisms at work when one visualizes what they know, and the information becomes one’s own?  How does the synthesis of knowledge become visualized in the mind?  The goal of this paper is to better understand the brain functions that allow a student to visualize, and imagine abstract concepts.  If we could see inside the mind of a student as they contemplated the “American revolution” what would we see?  How does one see this concept in their mind?  Where did it come from?  Where does one store it?  How can one edit it?  In short the answers to these questions are images, memory, ventral, and dorsal systems, and through feedback loops/mental reflection and rediscovery (Kosslyn, 1994).  These answers though do not provide a complete start to finish understanding of what it is to visualize an idea or concept, but they do provide a framework for the beginning of an analysis of such a complex topic of inquiry.  In addition what this paper is most interested in is the understanding of this process from a neuroscience perspective.  Therefore let us rephrase the question to “What does the brain do to visualize objects and concepts in our minds?” and start there.

In order to create structure to this investigation we will begin from the most macro of understandings and move towards the more micro afterwards.  In this case it is necessary to first define what is a mental image. It is theorized by Kosslyn that there are two levels of visualization, deep representations, and surface images (1994).  Using a computer as a metaphor, surface images are the computer screens, and deep representations are the computer memory chip where the information is stored using 1s and 0s.  The deep representations are the memory of your mind and that is where the image physically lives.  When one calls on a memory it is taken from the deep representation to become visible as a surface image.  Deep representation is similar in both humans and computers in the sense that no image is visible by looking directly in our memory or at a computer chip.   Instead deep representations use a code to store images for maximum efficiency.  From analysis of the monkey brain the areas of the brain called the ventral system actually store modality-specific visual memories, but these do not depict actual information (Fujita, Tanaka, Ito, & Cheng, 1992). When one visualizes an object such as a “chair” this code writes a sort of recipe that can latter be called upon to create a very accurate image.

Let us think of a “chair” again, and hold it in our minds.  What do we see or experience?  Most likely one will see a variety of images reflecting our understanding of chairs.  It may be a movie scene, it may be a photograph, or it may be a memory.  What brain functions allowed us to create these images?  Research indicates that 90% of the same brain areas and systems that work together in visual perception also work to allow us the ability to create mental images (Ganis et al., 2003; Kosslyn, Thompson, & Alpert, 1997).  This is an amazing evolutionary adaptation of the visual system, and it makes sense that mental imagery is not detached from visual perception.  In fact many times we use visual images to assist in visual perception, such as when we are trying to complete a puzzle we use the image in our mind to assist in completing the fractured puzzle in front of us (Barsalou, 1999).  The overt similarities in functions could be due to the bluntness of our current research tools, and we could later discover that mental imagery while originating from mental perception has evolved to be a much more complex and nuanced cognitive function.  For the time being though it is beneficial that there is a great body of research and understanding on the visual system due to it’s “outside” brain testable functions, because it gives us the foundation of understanding the hard to measure “inside only” brain functions of mental imagery.

Since perception is the most validated way to understand the parallel process of mental imagery it is necessary to understand how visual stimuli outside the mind become visual images within the mind.  In the brain there are many regions that work together to represent objects.  When we “see” something, light hits the retina creating impulses that are carried to the primary visual cortex, in the rear of the brain (Heegar, 1999). What is astounding about this region of the brain is that it is capable of taking a blueprint of the light that came through the retinas and creating a copy of that blueprint right on the surface of the actual brain.  This means the outline or shape of the object actually sits spread out over the brain.  Kosslyn defines these brain regions as retinotopically structured, meaning that the neurons are structured in a way like GPS locations, in that the physical organization matches up with the places on the spots of the eye (retina) that stimulated them.  Kosslyn further postulates that when an image enters the retina, it is also reflected in the cortex as an image representing the object, shape, or form one is seeing (Kosslyn, Thompson, and Ganis, 2006).

Human brain research using functional magnetic resonance imaging (fMRI) indicates many retinotopic areas are active when one is presented with a visual stimulus (Slotnick & Yantis, 2003).  The brain’s response to early visual stimulus mostly though takes place in the occipital lobe, at the back of the brain.   In this area, the brain will store information for only a short period of time, but during this brief period many areas of the brain can act upon that information separately.  This would be the stage or movie screen because it is where one can view the images. The form of the image that is represented in the mind relates to the form that is represented outside the mind. Therefore the form outside the mind directly dictates what brain areas will be activated.  An example is the research done by Heegar in which subjects where scanned using fMRI to reveal that a precise circular outline activated in their primary visual cortex when subjects looked at a circle (1999).  This evidence still only indicates what we can see (blood flow) of how the brain first responds to visual stimulus, not how the brain then interprets this information to make sense.

When a form or shape enters the “stage” of the occipital lobe it sends alerts and messages through two major neural systems.  A “chair” is just a form until then it is not yet understood as a “chair” until it communicates with the proceeding two systems.  It interesting to realize that until an object is recognized by matching it up with a similar form, it is just a shape in the mind.  There can be vast amounts of unidentified shapes in our minds that we have forgotten about, or have yet to associate with a memory or new visual input (Kosslyn, Thompson, Ganis, 2006). The first of the systems that help us make sense of these forms is the ventral system, which is used to analyze information about what exactly the object/form/concept/image in the mind is, because it is the area of the brain that stores visual memories.  It is located in the temporal lobes of the brain.  The other system is the dorsal system, which analyzes and deciphers the location or coordinates of the image.  The dorsal system is powered by the parietal lobes, which can be found towards the top side of the back of one’s head (Milner & Goodale, 1996).

Once a form has been recognized, the next step is accessing all the associated knowledge that we have accumulated relating to that object.  This next step is reliant on long-term memories.  Long-term memories use a combination of areas of the brain to store strongly associated pieces of information together.  These two areas are the association cortex, and sections of the anterior temporal lobes. In addition, the hippocampus is the creator or regulator of long-term memories.  The ventral system and the dorsal system both attempt to access any long term memory that might be associated with a recognized form such as a “chair” in order to provide supporting knowledge and to integrate this object into a more macro category (objects we sit on).  Furthermore what is of most interest due to our focus on what a concept looks like in the mind is the circular relationship between the areas of the brain involved in long term memory (predominantly the cortex, anterior temporal lobes, and hippocampus) and the areas of the brain responsible for holding an image to see with the “minds eye” the occipital lobe (Kosslyn, Thompson, Ganis, 2000).  This relationship allows one to alter, enhance, and even play with an image, which is necessary in creating knowledge by putting many pieces of information together and making it one’s own.

This is where the power of imagery lies.  This communication back and forth to the occipital lobe is crucial in creating the stage or movie screen previously mentioned, and allows the user to play director (Kosslyn, Thompson, Ganis, 2006).  In relating this process back to how a student might visualize the topic of the “American Revolution” it allows them (of course generalizing to a great degree) to take in new information lets say a reading of the “Battle of Brooklyn” search in their long term memory for associations (maybe even wrong ones such as a battle scene from the movie “Glory”, then to create an image of the event that one can then inspect for more knowledge or inaccuracies.  This cycle can be looped and repeated numerous times until satisfaction.  This reciprocal connection exists in almost all the visual processing areas of the mind.  There is a surprising amount of balance (although the perception response in the occipital lobes is stronger, than the imagination response, for the practical reason of reality over imagination) between the amount of information coming into the ventral and dorsal systems and the amount that they send backwards to the occipital lobe that is the “visual buffer” of the mind (Suzuki, Saleem, & Tanaka, 2000; Kosslyn1994).

The next question that one may ask and that many psychologist and neuroscientist have been trying to answer is, “Does image creation and manipulation abilities vary amongst individuals?”  To answer this question the researcher David Marks created the Vividness of Visual Imagery Questionnaire (VVIQ) (1973).  It is has been found that subjects who score high in vividness where more likely to be able to notice more detail changes about images than subjects who scored low on vividness (Rodway et al. 2006).  This measure has been further validated with the use of fMRI, and now the VVIQ2 is seen as an objective way to measure an individual’s ability to vividly or clearly “see” an object in their mind (Cui et al. 2007).  In can therefore be inferred that certain students may be able to recall more accurate and detail rich images that they can then investigate for knowledge.  It also encourages us to push further to discover what adaptations does someone with low vividness make in their mind, and are they possibly higher functioning on a different mental imaging capability?  This in fact is the case.  Kozhevnikoz, Hegarty, and Mayer have discovered that some individuals are better at “object imagery” which is the ability to construct vivid and detailed images of the surface quality and shape of objects.  Other individuals though are stronger in their “spatial imagery” ability which is the ability to visualize the relationships between objects, and it also refers to the ability to manipulate objects, for example spinning the “chair” around in your head to see the back of it.  These researchers discovered that it is rare for a person to be highly skilled in both areas (2002).

The task of creating mental images representing a knowledge area such as the “American Revolution” is much more difficult and complex than creating an image of say a “chair” but the underlying neurological systems used to complete the task are the same.  There are many specialized systems and subsystems that have been discovered in the process of perception.  This would indicate that future research may discover more intricately and subtle systems that regulate, control, and enable mental imagery.  Research in mental imaging seems to be converging on the idea that many divergent brain parts come together to allow us to create, and manipulate imagery.  This area seems to be the fertile ground of creativity and imagination, it also has been suggested that there is a great many parallels in mental imagery to mental simulation (Moulton, Kosslyn, 2009).  The complexity of the numerous brain regions involved presents many challenges to research, especially when trying to differentiate perception from imagery, but new advances in imaging, and other research methods hopefully will enable us to better understand and eventually improve how the brain visualizes concepts.

 

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