On the Neurological Substrates of Seeing, Touching, Smelling and Hearing in the Inferior Parietal Lobule (IPL)
http://tomartist.com/category/blog/ have come to me while I was in the process of painting. I pretty much just expect these thoughts to come up whenever I start the creative process. Sure enough, the come every time. Because I have an interest in art, therapy and neurology and I read in those areas, I was curious to know how this phenomenon could be explained neurologically. So I asked: “how does the act of painting facilitate or even trigger my thinking of these thoughts?” I set out to find some answers by doing what I usually do: asking everyone I know. I spoke to a few psychologists, blogged on a couple of forums, asked a few doctors (neurologists are unfortunately a little hard to come by because they are all busy rewriting the human narrative right now.) None of the answers completely satisfied me until I came across my new favorite site: http://www.brainmind.com/ . In reading chapter 3 on the Left Hemisphere, it started to hit me… Here is an excerpt from that chapter: “…there is considerable evidence that the evolution of language and linguistic thought are related to and in part are outgrowth of right hand temporal-sequential motor activity. The right hand appears to serve as a kind of motoric extension of language and thought in that it acts at the behest of linguistic impulses (Joseph, 1982). In fact, the hand and oral-facial musculature are neuronally represented in adjacent cortical space and are intimately interconnected with Broca's area which lies immediately posterior-lateral and anterior to these motor areas…Hence, we find that the ability to extract denotative meaning from language is dependent on the ability to organize and coordinate speech into temporal and interrelated units --an ability at which the left hemisphere excels, and an ability which is at least in part an outgrowth or a function of motoric processing and the predominant use of the right hand for gathering, tool making, food preparation, and related temporal and sequential activities…Ontogenetically, it is first via the hand that one comes to know the world so that it may be named and identified. For example, the infant first uses the hand to grasp various objects so they may be placed in the mouth and orally explored. As the child develops, rather than mouthing, more reliance is placed solely on the hand (as well as the visual system) so that information may be gathered through touch and manipulation…As the child and its brain matures, instead of predominantly touching, grasping, and holding, the fingers of the hand are used for pointing and then naming the object indicated. It is these same fingers which are later used for counting and the development of temporal-sequential reasoning; i.e. the child learns to count on his or her fingers, then to count (or name) by pointing at objects in space…In this regard, counting, naming, object identification, finger utilization, and hand control are ontogenetically linked. In fact, these capacities seem to rely on the same neural substrates for their expression; i.e. the left inferior parietal lobule. Hence, when the more posterior portions of the left hemisphere are damaged, naming (anomia), finger recognition (finger agnosia) object identification (agnosia), arithmetical abilities (acalculia), and temporal-sequential control over the hands and extremities (apraxia) are frequently compromised. It is relationships such as these which lend considerable credence to the argument that over the course of evolution the predominant usage of the right hand enabled the left brain to develop neurons specialized for counting, naming, and for subserving the development of the temporal-sequential properties necessary for the mediation of grammatical-syntactical speech and language.” So there you have it. As the neuroscientist Norman Doidge says: “Neurons that fire together, wire together”. Basically, if two things tend to occur consistently at the same time in your head, there are good chances that those two things are wired together in a direct kind of way. For example, if seeing your spouse makes you feel warm and fuzzy, then there is a neural connection between the act of seeing and the feeling state accompanying it. Straightforward no? As usual, when given the neurological explanation for why certain kinds of mental activity happen the way they do, we can go about observing all kinds of supporting anecdotal evidence for the theory. For example, we say: “can you see what I mean? Or do you see what I am saying?” and we also say: “a picture is worth a thousand words”. Seems to me that these ubiquitous statements could be references to the neurological relationships between the visual pathways, and the language centers of the brain, notably Wernicke’s area. No hard for us to imagine that the caveman was pointing at something long before he could name it. When language came on the scene, he was then able to point with his right hand and say: “danger” or “food”. So here is my summary of everything I think I have learned so far: When I am painting, I am holding my brush in my right hand and most precisely with my index, middle finger and thumb. Incidentally, index literally means pointing finger. These three fingers represent the most finely tuned motor control of the hand. While I am painting, sensory feedback is generated to and from the primary motor cortex through afferent and efferent neuronal signals. As this is going on, the visual or occipital lobe is firmly plugged in to the operation. The dorsal stream is gauging where my hand is moving, and all aspects related to visual spatial orientation while the ventral stream of the occipital lobe is activated in trying to figure out “what” it is looking at. The dorsal stream is gauging where the hand-object is moving while the ventral stream is gauging what we are looking at. This is referred to as the “what and where” functions of the visual cortex. Naturally, the “what” pathway is going to have to hook up with Wernicke’s area at some point. If it doesn’t do that, then we can’t name the object. Before it connects to Wernicke’s the ventral stream takes a run over to the Inferior Parietal Lobule (IPL) which performs an auditory-visual matching function. However, this is where things get interesting and I break away from what I think I know to what I think, I think I might know. At this point, there is not auditory language-visual matching possible because when I paint, I am essentially creating clouds of colour and chiseling shapes out of amorphous blobs of paint. Something like looking at a cloud. So I think here, my visual cortex is working hard to determine what it is looking at and it is coming up with the answer: “could be any multitude of things, keep searching…”. As it continues to search the database of memory and the language centers for suitable matches, it spends a lot of time coming up empty, finding no clear and concise answer to the question: “what am I looking at”. In the process, the Inferior Parietal Lobule is receiving signals from three main areas as a sort of relay station. The IPL is receiving signals from both streams of the visual cortex, from the auditory/language areas of the temporal lobe and from the primary sensory/motor cortex. The IPL ties in the three senses of touch, sight and sound, to do its best to categorize and label what the visual cortex is looking at. If it can’t find a word in the auditory cortex, it seems to go to asking: “what does the object feel like? Is it related to any memories, emotional experiences? What are the qualities of what is being looked at? Is it soft, hard, moving, still, smooth or rough?” To ask these questions the IPL naturally needs to go to memory and experience which are directly known through the body on a nonverbal level as implicit memory. Because I can spend somewhere between 4 and 8 hours playing around on the canvas in this non-verbal, amorphous mud of paint without having a clue of what is going to emerge, I personally believe that my left brain gets tired of working so hard. Remember, left brain is logical, systematic, detail oriented and more likely to come up with single words when naming things. My hypothesis here is that my right brain takes over the perceptual task of defining what my left brain is having such a hard time understanding. As a result, the wholistic, creative, spatial-perception oriented right brain strives to make sense of what is going on. Here is what Rhawn Joseph, Ph.D, Academic Press, New York, 2000) says in his chapter on the left hemisphere here: http://brainmind.net/BrainLecture3.html : “In most instances in which the IPL is activated via internal or external sources of stimulation, multiple trains of inquiry are initiated via the numerous interconnections this area maintains. Impressions, memories, ideas, and feelings which are in any manner associated with the initial stimulus probe, are aroused in response”. So while left brain can’t name what it is seeing, right brain is simultaneously grappling with the problem but because right brain is so generally minded it is pulling up data on anything and everything even remotely related to the stimulus probe and feeding it back to the IPL which then sends that data to the language centers so that my ideas (usually not directly related to painting) can be written down. So that is it for today’s tomartist update about art and neurology. I am glad we could spend this time together. You can see the post here: http://tomartist.com/category/blog/ As usual, I accept and respect your feedback on what I send you. Especially any corrections to the neurology data featured in this post. Enjoy the art. It is from my heart to yours.