A recent study out of the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig may shed some light on the neural mechanisms underlying dyslexia. Using magnetic resonance tomography (MRT) technology, researchers compared the brains of control subjects with those of dyslexic adults. Their findings pinpointed a very specific malfunction – originating in the medial geniculate body in the thalamus – in the second group. The impact of this study on the understanding and treatment of the disorder may be great, allowing scientists and doctors to more closely examine the way in which auditory information is processed from ear to cortex.
Dyslexia is one of many speech-language disorders currently studied and diagnosed. Below are three other disorders that affect the way in which certain people hear, read, write, and process language.
Aphasia, from the ancient Greek meaning “speechlessness”, is characterized by an inability to remember, speak, read, or write words. This acute disorder typically results from a head injury or stroke, but can on occasion develop gradually as a side effect of degenerative disease. Several types of aphasias exist, creating difficulty in either the reception or expression of language. Many cases of acute aphasia can be cured or ameliorated with the aid of a speech-language pathologist.
Stuttering or stammering is a condition that affects over three million Americans. A stutterer’s speech may be broken by repeated or prolonged syllables, or by unintended stops in speech. A number of genetic and neurophysiological aspects may result in an individual’s stuttering, as well as lifestyle factors such as stress and emotional duress and, in cases of sudden onset, physical trauma. This disorder can be successfully treated in many ways, including physical training, medication, support groups, and psychoanalysis.
Echolalia, from the ancient Greek combination of “echo” and “talk”, occasionally accompanies autism spectrum disorders, Tourette’s syndrome, Alzheimer’s disease, and stroke. It is characterized by repeated sounds and sentences and is considered a normal part of language development in children.
Figure: This figure compares the situation in the brain of dyslexics and the control group. The blue area depicts the auditory cortices and the green area represents the medial geniculate bodies. © MPI for Human Cognitive and Brain Sciences