Speech recovery after stroke

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.

Oprah’s and Einstein’s faces help spot dementia

New test designed for younger people reveals early-onset dementia

Simple tests that measure the ability to recognize and name famous people such as Albert Einstein, Bill Gates or Oprah Winfrey may help doctors identify early dementia in those 40 to 65 years of age, according to new Northwestern Medicine research.

The research appears in the August 13, 2013, print issue of Neurology, the medical journal of the American Academy of Neurology.

"These tests also differentiate between recognizing a face and actually naming it, which can help identify the specific type of cognitive impairment a person has," said study lead author Tamar Gefen, a doctoral candidate in neuropsychology at the Cognitive Neurology and Alzheimer’s Disease Center at Northwestern University Feinberg School of Medicine.

Gefen did the research in the lab of senior author Emily Rogalski, assistant research professor at Northwestern’s Cognitive Neurology and Alzheimer’s Disease Center.

Face recognition tests exist to help identify dementia, but they are outdated and more suitable for an older generation.

"The famous faces for this study were specifically chosen for their relevance to individuals under age 65, so that the test may be useful for diagnosing dementia in younger individuals," Rogalski said. An important component of the test is that it distinguishes deficits in remembering the name of a famous person from that of recognizing the same individual, she noted.

The study also used quantitative software to analyze MRI scans of the brains of the individuals who completed the test to understand the brain areas important for naming and recognition of famous faces.

For the study, 30 people with primary progressive aphasia, a type of early onset dementia that mainly affects language, and 27 people without dementia, all an average age of 62, were given a test. The test includes 20 famous faces printed in black and white, including John F. Kennedy, Lucille Ball, Princess Diana, Martin Luther King Jr. and Elvis Presley.

Participants were given points for each face they could name. If the subject could not name the face, he or she was asked to identify the famous person through description. Participants gained more points by providing at least two relevant details about the person. The two groups also underwent MRI brain scans.

Researchers found that the people who had primary progressive aphasia, a form of early onset dementia, performed significantly worse on the test, scoring an average of 79 percent in recognition of famous faces and 46 percent in naming the faces, compared to 97 percent in recognition and 93 percent on naming for those free of dementia.

The study also found that people who had trouble putting names to the faces were more likely to have a loss of brain tissue in the left temporal lobe of the brain, while those with trouble recognizing the faces had tissue loss on both the left and right temporal lobe.

"In addition to its practical value in helping us identify people with early dementia, this test also may help us understand how the brain works to remember and retrieve its knowledge of words and objects," Gefen said.

Early brain stimulation may help stroke survivors recover language function

Non-invasive brain stimulation may help stroke survivors recover speech and language function, according to new research in the American Heart Association journal Stroke.

Between 20 percent to 30 percent of stroke survivors have aphasia, a disorder that affects the ability to grasp language, read, write or speak. It’s most often caused by strokes that occur in areas of the brain that control speech and language.

“For decades, skilled speech and language therapy has been the only therapeutic option for stroke survivors with aphasia,” said Alexander Thiel, M.D., study lead author and associate professor of neurology and neurosurgery at McGill University in Montreal, Quebec, Canada. “We are entering exciting times where we might be able in the near future to combine speech and language therapy with non-invasive brain stimulation earlier in the recovery. This could result in earlier and more efficient aphasia recovery and also have an economic impact.”

In the small study, researchers treated 24 stroke survivors with several types of aphasia at the rehabilitation hospital Rehanova and the Max-Planck-Institute for neurological research in Cologne, Germany. Thirteen received transcranial magnetic stimulation (TMS) and 11 got sham stimulation.

The TMS device is a handheld magnetic coil that delivers low intensity stimulation and elicits muscle contractions when applied over the motor cortex.

During sham stimulation the coil is placed over the top of the head in the midline where there is a large venous blood vessel and not a language-related brain region. The intensity for stimulation was lower intensity so that participants still had the same sensation on the skin but no effective electrical currents were induced in the brain tissue.

Patients received 20 minutes of TMS or sham stimulation followed by 45 minutes of speech and language therapy for 10 days.

The TMS groups’ improvements were on average three times greater than the non-TMS group, researchers said. They used German language aphasia tests, which are similar to those in the United States, to measure language performance of the patients.

“TMS had the biggest impact on improvement in anomia, the inability to name objects, which is one of the most debilitating aphasia symptoms,” Thiel said.

Researchers, in essence, shut down the working part of the brain so that the stroke-affected side could relearn language. “This is similar to physical rehabilitation where the unaffected limb is immobilized with a splint so that the patients must use the affected limb during the therapy session,” Thiel said.

“We believe brain stimulation should be most effective early, within about five weeks after stroke, because genes controlling the recovery process are active during this time window,” he said.

Shift of Language Function to Right Hemisphere Impedes Post-Stroke Aphasia Recovery

In a study designed to differentiate why some stroke patients recover from aphasia and others do not, investigators have found that a compensatory reorganization of language function to right hemispheric brain regions bodes poorly for language recovery. Patients who recovered from aphasia showed a return to normal left-hemispheric language activation patterns. These results, which may open up new rehabilitation strategies, are available in the current issue of Restorative Neurology and Neuroscience.

“Overall, approximately 30% of patients with stroke suffer from various types of aphasia, with this deficit most common in stroke with left middle cerebral artery territory damage. Some of the affected patients recover to a certain degree in the months and years following the stroke. The recovery process is modulated by several known factors, but the degree of the contribution of brain areas unaffected by stroke to the recovery process is less clear,” says lead investigator Jerzy P. Szaflarski, MD, PhD, of the Departments of Neurology at the University of Alabama and University of Cincinnati Academic Health Center.

For the study, 27 right-handed adults who suffered from a left middle cerebral artery infarction at least one year prior to study enrollment were recruited. After language testing, 9 subjects were considered to have normal language ability while 18 were considered aphasic. Patients underwent a battery of language tests as well as a semantic decision/tone decision cognitive task during functional MRI (fMRI) in order to map language function. MRI scans were used to determine stroke volume.

The authors found that linguistic performance was better in those who had stronger left-hemispheric fMRI signals while performance was worse in those who had stronger signal-shifts to the right hemisphere. As expected, they also found a negative association between the size of the stroke and performance on some linguistic tests. Right cerebellar activation was also linked to better post-stroke language ability.

The authors say that while a shift to the non-dominant right hemisphere can restore language function in children who have experienced left-hemispheric injury or stroke, for adults such a shift may impede recovery. For adults, it is the left hemisphere that is necessary for language function preservation and/or recovery.

Robot-Delivered Speech and Physical Therapy

In one of the earliest experiments using a humanoid robot to deliver speech and physical therapy to a stroke patient, researchers at the University of Massachusetts Amherst saw notable speech and physical therapy gains and significant improvement in quality of life.

Regarding the overall outcome, speech language pathologist and study leader Yu-kyong Choe says, “It’s clear from our study of a 72-year-old male stroke client that a personal humanoid robot can help people recover by delivering therapy such as word-retrieval games and arm movement tasks in an enjoyable and engaging way.”

A major focus of this case study was to assess how therapy interventions in one domain, speech, affected interventions in another, physical therapy, in two different delivery scenarios. Despite the importance of working with other professionals, the authors point out, until now it has been “largely unknown how interventions by one type of therapy affects progress in others.”

The client, with aphasia and physical disability on one side, completed a robot-mediated program of only speech therapy for five weeks followed by only physical therapy for five weeks in the sole condition, but for the sequential condition he attended back-to-back speech and physical therapy sessions for five weeks.

Over the course of the experiment, the client made “notable gains in the frequency and range of the upper-limb movements,” the authors say. He also made positive gains in verbal expression. Interestingly, his improvements in speech and physical function were much greater when he engaged in only one therapy than when the two therapies were paired in sessions immediately following each other. The authors summarize that in such a sequential schedule “speech and physical functions seemed to compete for limited resources” in the brain. Their work is described in the current issue of the journal Aphasiology.

Choe and computer science researcher and robot expert Rod Grupen, director of the Laboratory for Perceptual Robotics at UMass Amherst, are in the second year of a $109,251 grant from the American Heart Association to investigate the effect of stroke rehabilitation delivered by a humanoid robot, uBot-5. It is a child-sized unit with arms and a computer screen through which therapists interact with the client.

Choe, Grupen and colleagues are seeking ways to bring more and longer-term therapy and social contact to people recovering from stroke. It’s estimated that 3 million Americans daily experience the debilitating effects of stroke. But even after years, they can recover significant function with intensive rehabilitation, says Choe. The bad news is that this is rarely available or accessible due to a shortage of therapists and lack of coverage for long-term treatment. Many people are left with chronic low function, which can lead to social isolation and depression.

While some may object to robots delivering therapy, the need is great and definitely not being met now, especially in rural areas, Grupen and Choe point out. They hope to aid human-to-human interaction, so a robot can temporarily take the therapist’s place. Grupen says, “In addition to improving quality of life, if we can support a client in the home so they can delay institutionalization, we can improve outcomes and make a huge impact on the cost of elder care. There are 70 million baby boomers beginning to retire now.”

“Stroke rehabilitation is such a monumental financial problem everywhere in the world, that’s where it can pay for itself,” he adds. “A personal robot could save billions of dollars in elder care while letting people stay in their own homes and communities. We’re hoping for a win-win where our elders live better, more independent and productive lives and our overtaxed healthcare resources are used more effectively.”

Training speech networks to treat aphasia

About 80,000 people develop aphasia each year in the United States alone. Nearly all of these individuals have difficulty speaking. For example, some patients (nonfluent aphasics) have trouble producing sounds clearly, making it frustrating for them to speak and difficult for them to be understood. Other patients (fluent aphasics) may select the wrong sound in a word or mix up the order of the sounds. In the latter case, “kitchen” can become “chicken.” Blumstein’s idea is to use guided speech to help people who have suffered stroke-related brain damage to rebuild their neural speech infrastructure.

Blumstein has been studying aphasia and the neural basis of language her whole career. She uses brain imaging, acoustic analysis, and other lab-based techniques to study how the brain maps sound to meaning and meaning to sound.

What Blumstein and other scientists believe is that the brain organizes words into networks, linked both by similarity of meaning and similarity of sound. To say “pear,” a speaker will also activate other competing words like “apple” (which competes in meaning) and “bear”(which competes in sound). Despite this competition, normal speakers are able to select the correct word.

In a study published in the Journal of Cognitive Neuroscience in 2010, for example, she and her co-authors used functional magnetic resonance imaging to track neural activation patterns in the brains of 18 healthy volunteers as they spoke English words that had similar sounding “competitors” (“cape” and “gape” differ subtly in the first consonant by voicing, i.e. the timing of the onset of vocal cord vibration). Volunteers also spoke words without similar sounding competitors (“cake” has no voiced competitor in English; gake is not a word). What the researchers found is that neural activation within a network of brain regions was modulated differently when subjects said words that had competitors versus words that did not.

One way this competition-mediated difference is apparent in speech production is that words with competitors are produced differently from words that do not have competitors. For example, the voicing of the “t” in “tot” (with a voiced competitor ‘dot’) is produced with more voicing than the “t” in “top” (there is no ‘dop’ in English). Through acoustic analysis of the speech of people with aphasia, Blumstein has shown that this difference persists, suggesting that their word networks are still largely intact.

New Technique Helps Stroke Victims Communicate

Stroke victims affected with loss of speech caused by Broca’s aphasia have been shown to speak fluidly through the use of a process called “speech entrainment” developed by researchers at the University of South Carolina’s Arnold School of Public Health.

Aphasia, a severe communication problem caused by damage to the brain’s left hemisphere and characterized by halting speech, occurs in about one-third of people who have a stroke and affects personal and professional relationships. Using the speech entrainment technique, which involves mimicking other, patients showed significant improvement in their ability to speak.

The results of the study are published in a recent issue of the neurology journal Brain.

"This is the first time that we have seen people with Broca’s aphasia speak in fluent sentences,” said Julius Fridriksson, the study’s lead researcher and a professor with the Department of Communication Sciences and Disorders at the Arnold School. “It is a small study that gives us an understanding of how the brain functions after a stroke, and it offers hope for thousands of people who suffer strokes each year."

In Fridriksson’s study, 13 patients completed three separate behavioral tasks that were used to understand the effects of speech entrainment on speech production. During the “speech entrainment–audio visual" portion of the study, participants attempted to mimic a speaker in real-time whose mouth was made visible on the 3.5-inch screen of an iPod Touch and whose speech was heard via headphones.

The “speech entrainment–audio only” condition involved real-time mimicking speech presented via headphones with the screen of the iPod blank. During a spontaneous speech condition, patients spoke about a given topic without external aid.

Each patient also completed a three-week training phase where they practiced speech every day with the aid of speech entrainment. Overall, the training resulted in improved spontaneous speech production, something that is relatively rare in this population. Ultimately the patients were able to produce a short script about their stroke to tell to other people.

Neuroimaging results from the patient subjects have also given Fridriksson and his research team a greater understanding of the mechanism involved in speech entrainment.

"Preliminary results suggest that training with speech entrainment improves speech production in Broca’s aphasia, providing a potential therapeutic method for a disorder that has been shown to be particularly resistant to treatment," Fridriksson said.