The Telltale Hand: How Writing Reveals the Damaged Brain
By: Marc J. Seifer, Ph.D.
Signing your name or scribbling a grocery list may seem a simple, mundane activity. In fact, it is the result of a complex interaction of physical and mental processes involving cooperation among your brain’s cognitive, motor, and emotion areas, down through the brain stem and the spinal cord, and out to your hand.
No wonder, then, that accidents and diseases that change the brain leave important calling cards in our handwriting. Handwriting expert Marc J. Seifer, Ph.D., takes us through more than a dozen examples—some dramatic, some subtle—of how a science-savvy Sherlock Holmes would diagnose a patient’s “brain writing.”
Look at this handwriting sample from a spry and healthy 97-year-old woman. It shows good control, balance, and a disciplined yet flowing style that combines angles and curves. One could quibble about some tightness here and there, and some resting points at the ends of words, such as in the “s” of “was” in line 4, but overall this handwriting represents an ideal to which we all might aspire: a brain that has worked just fine for almost an entire century.
Written language is a further evolution of the highly complex human capability for spoken language that probably goes back at least 250,000 years, to the time when our distant ancestors were just beginning to make tools. Because it is both neurological and psychological, handwriting is a window into the complex interplay of brain and mind.
If the brain is injured by accident or disease, handwriting will be affected in specific ways that scientists are only beginning to delineate. Conversely, studying handwriting may give us important clues to how and where a brain is malfunctioning.
INVENTING THE ULTIMATE “TOOL”
The Russian neurologist A.R. Luria pointed out that the development of language enabled humans to create symbolic representations of events and physical objects. Through a process of “inner speech,” man, unlike any other animal, was freed from the confines of the present to reflect upon the past, learn from purely verbal instruction, and plan for the future. Luria even suggested that voluntary behavior and consciousness itself evolved because of the development of language, and that thinking in words to organize the world dramatically increased cerebral complexity.1 Written language breaks the bounds of the present still further by enabling communication between people in distant places and times.
Our modern Latin alphabet traces its descent from exquisitely realistic prehistoric cave drawings and simpler carvings and line drawings dating back about 35,000 years to the advent of petroglyphs, which evolved into hieroglyphics. Some 6,000 years ago, merchants were marking their property with cuneiform signs on soft clay. Papyrus scrolls apparently go back 5,000 years. Chinese and Phoenician (which evolved into Hebrew) alphabets trace their roots back about 4,000 years. A millennium later, the lean Greek and Latin alphabets came into being.
Some written languages create all words out of a relatively small alphabet— for example our 26 letters—while others, like the Chinese, have thousands of abstract symbols. But all written languages involve specialized activities and communication among many areas of the brain.
Handwriting occurs through the interactions of many structures and circuits in the brain. When one portion of the brain is damaged, handwriting is affected in a way that reflects the function of that structure or circuit.
Courtesy of the News Office of the Dana Foundation
A JOURNEY THROUGH THE BRAIN
Most humans have their predominant language center in the brain’s left hemisphere, although signatures and other graphic pictograms usually get transferred to, or at least get processed by, the right hemisphere. There must be communication between the hemispheres because the essential picture of the event, or the point being made, is located in the right hemisphere and gets translated into language in the left.
Anatomically, even scrawling a quick note to yourself, “pick up milk,” is a complex voluntary procedure, engaging the cooperation of all lobes of your cerebral cortex with other parts of your brain—including the limbic system, hippocampus, brain stem, and cerebellum—and finally the spinal cord, which sends impulses out to your hands and fingers. Damage to any of these parts will affect your fine motor control and show up as some type of break in the rhythm or control of your handwriting.
The sequence that produces handwriting begins at “control central,” the cingulate cortex in your frontal lobes where the decision to initiate the process is made, although the limbic system also acts at the outset to color the emotional content of the motor sequence. The visual cortex sees the paper to be written on and internally pictures how the writing will look, and a part of the parietal lobe called the left angular gyrus converts the visual perception of letters into the comprehension of words. If needed, Broca’s and Wernicke’s areas kick in to process and comprehend spoken words. The corpus callosum, which connects the cerebral cortex’s left and right hemispheres, combines the pictorial/holistic right-brain procedures with their sequential/linguistic left-brain counterparts. The parietal lobe then coordinates all these signals with the motor cortex, producing the motor signal to the arm, hand, and fingers.2
Once the signal is initiated, it travels along the pyramidal track—which monitors fine movements—to the fingers. Along the way, it passes through the limbic system, where emotion can again affect the signal, through the hippocampus, where memory can have an effect, and through the basal ganglia, which modifies the fine motor control necessary to write. When passing through areas in the brainstem such as the pons and the medulla, the signal can be altered by primitive impulses or unconscious desires. Before the signal exits the brain, the cerebellum plays a critical role by programming the entire process into an automatic habit. This programmed routine combines physical aspects of writing with its psychosocial and emotional counterparts. Like speech, handwriting is learned through interaction with other people and is therefore influenced by social and environmental variables, as well as by our neural architecture.
“Handwriting,” explains Luria, “starts out as a chain of isolated motor movements, but is radically altered with practice, and converted into a ‘kinetic melody’ no longer requiring the memorizing of the visual form of each letter or the motor impulse for making every stroke.”3 Handwriting’s cerebral organization changes, becoming more deeply ingrained and requiring less energy to execute. It is, in effect, a multilayered, dynamic, kinesthetic memory that involves picturing how the letters are formed, how the writing looks, and how it feels to move the pen across the page.
As we write, what is called inner speech also plays a crucial role. You can see an example of it in the note on the previous page written by a 20-year-old community college student with a severe learning disability, a speech impediment, dyslexia, and, most likely, auditory aphasia. It can take her up to two hours to partially complete a 45-minute exam. When she speaks, she leaves off the ends of many words, a tendency reflected when she writes the word “scare.” Because she does not pronounce it as “scared,” she does not hear the “d” and so does not write it. You can also see her dyslexia in the third sentence, where she misplaces the word “I.” One could guess that she has a dysfunction in her frontal lobes and in Wernicke’s area that, in turn, has caused a problem in Broca’s area and also, no doubt, in the left angular gyrus, whose task it is to combine speech with the visual perception of words and their kinesthetic output.
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