"Titan is a lovely, baffling and instructive world which we suddenly realize is accessible for exploration: by fly-bys to determine the gross global parameters and to search for breaks in the clouds; by entry probes to sample the red clouds and unknown atmosphere; and by landers to examine a surface like none we know. Titan provides a remarkable opportunity to study the kinds of organic chemistry that on Earth may have led to the origin of life. Despite the low temperatures, it is by no means impossible that there is a Titanian biology. The geology of the surface may be unique in all the solar system. Titan is waiting…" — Carl Sagan, Broca’s Brain (1979)
Hello everybody! I know this is late, but June is global Aphasia awareness month.
Aphasia is an impairment of language ability that can range from inabilty to pronounce word order to loss of ability to form sentences. Usually the result of brain damage (stroke, seizure, infection, medication reaction, tumor, dementia, etc), aphasia can also be relative to certain developmental disorders.
Age of onset is not limited to childhood or adulthood - a person can lose their ability to use words at any age - but Aphasia could be episodic or chronic. In the majority of Aphasia cases, overall intellect is not affected - just the ability to communicate or recall words.
There are many different causes for Aphasia. This makes any treatment for the disorder patient-specific. As such, an individual with Aphasia is usually assigned a multi-displinary large team of expensive specialists. Most people cannot afford hiring a group of doctors, however, so many Aphasia sufferers would be left in the dark (speech dark?) - being able to comprehend but not communicate - without the existence of several charities.
In the 19th century, a speechless patient wasted away in the Bicetre Hospital in France for 21 years. He was known as ‘Tan’ for the only word he could say, and for 150 years, his identity has remained a mystery. In 1861, as Tan lay dying, the famous physician Paul Broca encountered the patient. When the ill-fated patient died, Broca autopsied his brain. Broca noticed a lesion in a part of the brain tucked up behind the eyes. He concluded that the brain region was responsible for language processing. But despite Tan becoming one of the most famous medical patients in history, he was never identified until now. A 2007 study in the journal Brain revealed the extent of the lesion using MRI imaging. A recent study identified the patient as a Monsieur Louis Leborgne, a craftsman who had suffered from epilepsy his whole life.
The laryngeal folds are where voice is produced, and is located just below where the pharynx separates into the esophagus and the larynx. During the swallowing action, if solid matter enters the larynx, a strong coughing reflex is triggered to protect the lungs. This is also triggered at other times, if solid matter touches the glottis. Should that coughing reflex not dislodge the bolus, suffocation can occur.
During puberty, the protective laryngeal cartilage (specifically the thyroid cartilage) expands and forms the Adam’s apple - in males, the cartilage fuses at approximately a 90° angle, and in females, it fuses at approximately 120°. Everyone has an Adam’s apple! The difference in fusion means that the male vocal cords have more room to grow outward, and form a deeper voice.
When an adult is hanged, throttled or strangled in a murder, the hyoid bone - the only bone in the body not directly connected to other bones - is almost always cracked or split apart. However, since it does not completely fuse until early adulthood, children and adolescents do not always show this distinctive sign.
Atlas d’Anatomie Descriptive du Corps Humain. C. Bonamy and Paul Broca, 1866.
Neuroscientists find Broca’s area is really two subunits, each with its own function
A century and a half ago, French physician Pierre Paul Broca found that patients with damage to part of the brain’s frontal lobe were unable to speak more than a few words. Later dubbed Broca’s area, this region is believed to be critical for speech production and some aspects of language comprehension.
However, in recent years neuroscientists have observed activity in Broca’s area when people perform cognitive tasks that have nothing to do with language, such as solving math problems or holding information in working memory. Those findings have stimulated debate over whether Broca’s area is specific to language or plays a more general role in cognition.
A new study from MIT may help resolve this longstanding question. The researchers, led by Nancy Kanwisher, the Walter A. Rosenblith Professor of Cognitive Neuroscience, found that Broca’s area actually consists of two distinct subunits. One of these focuses selectively on language processing, while the other is part of a brainwide network that appears to act as a central processing unit for general cognitive functions.
"I think we’ve shown pretty convincingly that there are two distinct bits that we should not be treating as a single region, and perhaps we shouldn’t even be talking about ‘Broca’s area’ because it’s not a functional unit," says Evelina Fedorenko, a research scientist in Kanwisher’s lab and lead author of the new study, which recently appeared in the journal Current Biology.
This is the picture I’m submitting to sci-universe for the collage she will be making of similar submissions! (I really had to think about this so I could cram everything in, heh.) I guess you could call me a hardcore fan.
People blog, they don’t lbog, and they schmooze, not mshooze. But why is this? Why are human languages so constrained? Can such restrictions unveil the basis of the uniquely human capacity for language?
A groundbreaking study published in PLOS ONE by Prof. Iris Berent of Northeastern University and researchers at Harvard Medical School shows the brains of individual speakers are sensitive to language universals. Syllables that are frequent across languages are recognized more readily than infrequent syllables. Simply put, this study shows that language universals are hardwired in the human brain.
Language universals have been the subject of intense research, but their basis remains elusive. Indeed, the similarities between human languages could result from a host of reasons that are tangential to the language system itself. Syllables like lbog, for instance, might be rare due to sheer historical forces, or because they are just harder to hear and articulate. A more interesting possibility, however, is that these facts could stem from the biology of the language system. Could the unpopularity of lbogs result from universal linguistic principles that are active in every human brain?
To address this question, Dr. Berent and her colleagues examined the response of human brains to distinct syllable types—either ones that are frequent across languages (e.g., blif, bnif), or infrequent (e.g., bdif, lbif). In the experiment, participants heard one auditory stimulus at a time (e.g., lbif), and were then asked to determine whether the stimulus includes one syllable or two while their brain was simultaneously imaged.
Results showed the syllables that were infrequent and ill-formed, as determined by their linguistic structure, were harder for people to process. Remarkably, a similar pattern emerged in participants’ brain responses: worse-formed syllables (e.g., lbif) exerted different demands on the brain than syllables that are well-formed (e.g., blif).
UNIVERSALLY HARDWIRED BRAINS
The localization of these patterns in the brain further sheds light on their origin. If the difficulty in processing syllables like lbif were solely due to unfamiliarity, failure in their acoustic processing, and articulation, then such syllables are expected to only exact cost on regions of the brain associated with memory for familiar words, audition, and motor control. In contrast, if the dislike of lbif reflects its linguistic structure, then the syllable hierarchy is expected to engage traditional language areas in the brain.
While syllables like lbif did, in fact, tax auditory brain areas, they exerted no measurable costs with respect to either articulation or lexical processing. Instead, it was Broca’s area—a primary language center of the brain—that was sensitive to the syllable hierarchy.
These results show for the first time that the brains of individual speakers are sensitive to language universals: the brain responds differently to syllables that are frequent across languages (e.g., bnif) relative to syllables that are infrequent (e.g., lbif). This is a remarkable finding given that participants (English speakers) have never encountered most of those syllables before, and it shows that language universals are encoded in human brains.
The fact that the brain activity engaged Broca’s area—a traditional language area—suggests that this brain response might be due to a linguistic principle. This result opens up the possibility that human brains share common linguistic restrictions on the sound pattern of language.
The findings from newborns are particularly striking because they have little to no experience with any such syllable. Together, these results demonstrate that the sound patterns of human language reflect shared linguistic constraints that are hardwired in the human brain already at birth.
With right-handed people, it is positioned in the left side of the brain; left-handed people have it (usually) in the right side: the location of speech production has been known for quite some time. But it is not that simple, states psychologist Gesa Hartwigsen, Professor at Kiel University. In her current scientific publication, published in the magazine Proceedings of the National Academy of Science of the USA (PNAS), she investigates which areas in the brain really are in charge of speech, and how these interact. Her findings are supposed to help patients who have speech production problems or aphasia following a stroke.
Comprehending & Speaking
Gesa Hartwigsen and her team started by analysing speech production. They let healthy right-handed test persons listen to words, which they should then repeat. “These were pseudo words such as `beudo`. In German, they don’t have any associated meaning. Therefore, when hearing and repeating these words, no areas of the brain that had a connection to the meaning of what had been heard were activated”, said Hartwigsen.
The psychologist applies a combination of non-invasive methods (fMRI– functional magnetic resonance imaging and TMS – transcranial magnetic stimulation) to deduce what happens in the brain during the test. “We thus proved that the left hemisphere, as expected, was activated during speech production, while the right hemisphere did not actively contribute to language function”, explains Hartwigsen. This is the regular functionality within a healthy brain. From these results as well as others, scientists had up to now deduced that the right hemisphere did not contribute to speech production in the healthy system and was therefore suppressed.
Interfering & Measuring
With a second test, the Kiel University scientists simulated a dysfunction in the brain comparable to a stroke. A magnetic coil transmits a current pulse that interrupts the function of the area responsible for producing speech (Broca’s Area) in the left hemisphere. This completely harmless method influences the speech production of the volunteers for about 30 to 45 minutes. “During this period, the ability to listen and repeat was tested again. While we observed a suppressed activity in the left hemisphere during repeating, with some test persons taking longer to repeat the pseudo words, we also found unexpected activities in the right hemisphere”, reports Hartwigsen.
The right hemisphere showed increased activity during pseudo word repetition. The more the activity in the right Borca’s Area increased, the faster the volunteers were able to solve their speech tests. The right hemisphere also increased its facilitatory influence on the right hemisphere, a finding that was not observed prior to the TMS-induced lesion. “This reaction lends further support to the notion that the right hemisphere area reacts to the dysfunction of the left hemisphere and tries to compensate for the lesion.” Does the right hemisphere have a supporting influence and does it play an active role in speech production? So far, the common opinion was that it does not.
Result & Outlook
The findings of Gesa Hartwigsen and her team show an interaction of both hemispheres during speech repetition. When the left hemisphere is suppressed for example by a stroke, the right hemisphere could actively facilitate speech production. “By stimulating the right hemisphere, it could be possible to support speech recovery”, speculates the scientist. Here, timing would be very important. “Right after a stroke, we could support the right hemisphere. But when the remaining areas of the left hemisphere are ready to do their work again, it might be more helpful if the right hemisphere was suppressed. During this phase, we could stimulate the left hemisphere instead. The correct timing can therefore be crucial for recovery of speech after a stroke.”
In collaboration with the Department of Neurology at Kiel University, a stroke specialist from Leipzig and doctoral students of Medicine and Psychology, Gesa Hartwigsen has started a follow-up study on the recent publication. “We would like to find out more about the collaboration of the hemispheres and the right timing in helping stroke patients to recover”, says Hartwigsen. Her field of research is fairly new within the cognitive neuroscience. Nevertheless, she is positive that it will offer practical help in the form of concrete therapies within the next ten to fifteen years.