Nina Dronkers

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Nina Dronkers is an American cognitive neuroscientist. She is known for her studies of aphasia (language impairments) and their application for understanding brain systems involved in normal language abilities. She is a professor in the Psychology Department at the University of California, Berkeley, and a faculty member of the Helen Wills Neuroscience Institute.  She is also an Emerita Research Career Scientist of the Veterans Administration Northern California Health Care System where she established the Center for Aphasia and Related Disorders.  She serves as a consultant for the Memory and Aging Center at UCSF Medical Center. In addition, she is an adjunct professor in the Department of Neurology, University of California, Davis, School of Medicine.  She has published over 120 scientific papers and is the co-author with Lise Menn of a textbook: Psycholinguistics: Introduction and Applications, Second edition.

Contents

Education

Nina Dronkers was born at Alta Bates hospital in Berkeley, California, in 1955 and grew up nearby in Kensington, California, where she attended K-12 public schools.  She received her undergraduate degree in linguistics in 1976, her MA in Educational Psychology in 1978, and her PhD in neuropsychology in 1985, all from the University of California, Berkeley.  In 1982 and 1999 she was a visiting scholar at the Max-Planck-Institut fur Psycholinguistik, Nijmegen, The Netherlands.

Research

In the early part of her career, Dronkers questioned a long-held assumption about which areas of the brain were most critically involved in spoken language. In 1861, the French physician and neuroanatomist Paul Broca presented a paper describing two of his patients who had an expressive aphasia, difficulty in producing spoken language. In addition to a description of their impaired language. Broca presented autopsy findings, and noted that both patients had damage to the frontal lobe in the left hemisphere of the brain.   Based on his careful work in documenting this brain-behavior relationship, the brain region became known as Broca's area, and expressive aphasia became known as Broca's aphasia.

Over 100 years later, Dronkers obtained permission to re-examine the brains of Broca's original patients. Fortunately, the brains had been preserved whole, although they had not been sliced and were required to remain so.  With the help of French collaborators, Dronkers removed the brains from their preservation jars and placed them in a modern MRI scanner; the MRI images revealed that theses patients had suffered much more damage to the brain than Broca could have known from just studying the outer surface. Their lesions extended to deeper layers beyond the left frontal lobe, including portions of insular cortex and critical white matter pathways below the cortex. [1]

In another peer-reviewed paper [2] (2), Dronkers analyzed brain scans from several stroke patients who suffered from a speech production disorder known as apraxia of speech (AOS). AOS is a symptom observed in most patients who are diagnosed with Broca's aphasia. She found that, rather than Broca's area, this speech production disorder was associated with a portion of insular cortex which is tucked beneath the lateral surface of the brain. Like Broca's original patients, these patients had significant subcortical damage that involved insular cortex and adjacent white matter Dronkers also showed that a matched group of stroke patients without AOS did not have damage to this portion of insular cortex, thus confirming the specificity of the result. This work has been cited more than 1400 times in published articles (Google scholar, June 2021).

Her findings have been highly influential, and according to google scholar, have been cited in published work more than 21,000 times. Scientists studying speech and language across the world had used Broca's area for many decades as a biological marker of speech production and fluency in the brain.   Dronkers defined a new area of the brain that is critical for language expression, and this region is sometimes now referred to as “Dronkers’ area”. [3] [4]  

Dronkers’ work helped lead the way for more precise studies of brain regions associated with discrete speech and language functions. Her work emphasized the critical role that subcortical brain connections play in supporting language. She and her collaborators developed new methods to more precisely analyze stroke lesions in large groups of neurological patients with specific language deficits. [5]   With these analyses, each patient's brain scan is virtually cut into 1 millimeter cubes called voxels, with the patient's lesion either inside or outside each voxel. Then, patients’ behavioral performance (e.g., AOS, degree of expressive aphasia) is related to each of these discrete voxels in a statistical manner that allows for pinpointing of specific brain voxels associated with a particular aspect of language. This technique is known as  voxel-based-lesion-symptom mapping or VLSM. It provided a new tool for examining relationships between discrete brain areas and selected deficits in language and cognition.  

Honors

Related Research Articles

<span class="mw-page-title-main">Aphasia</span> Inability to comprehend or formulate language

In aphasia, a person may be unable to comprehend or unable to formulate language because of damage to specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine, but aphasia due to stroke is estimated to be 0.1–0.4% in the Global North. Aphasia can also be the result of brain tumors, epilepsy, autoimmune neurological diseases, brain infections, or neurodegenerative diseases.

<span class="mw-page-title-main">Expressive aphasia</span> Language disorder involving inability to produce language

Expressive aphasia is a type of aphasia characterized by partial loss of the ability to produce language, although comprehension generally remains intact. A person with expressive aphasia will exhibit effortful speech. Speech generally includes important content words but leaves out function words that have more grammatical significance than physical meaning, such as prepositions and articles. This is known as "telegraphic speech". The person's intended message may still be understood, but their sentence will not be grammatically correct. In very severe forms of expressive aphasia, a person may only speak using single word utterances. Typically, comprehension is mildly to moderately impaired in expressive aphasia due to difficulty understanding complex grammar.

<span class="mw-page-title-main">Language center</span> Speech processing areas of the brain

In neuroscience and psychology, the term language center refers collectively to the areas of the brain which serve a particular function for speech processing and production. Language is a core system that gives humans the capacity to solve difficult problems and provides them with a unique type of social interaction. Language allows individuals to attribute symbols to specific concepts, and utilize them through sentences and phrases that follow proper grammatical rules. Finally, speech is the mechanism by which language is orally expressed.

<span class="mw-page-title-main">Receptive aphasia</span> Language disorder involving inability to understand language

Wernicke's aphasia, also known as receptive aphasia, sensory aphasia, fluent aphasia, or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding written and spoken language. Patients with Wernicke's aphasia demonstrate fluent speech, which is characterized by typical speech rate, intact syntactic abilities and effortless speech output. Writing often reflects speech in that it tends to lack content or meaning. In most cases, motor deficits do not occur in individuals with Wernicke's aphasia. Therefore, they may produce a large amount of speech without much meaning. Individuals with Wernicke's aphasia often suffer of anosognosia – they are unaware of their errors in speech and do not realize their speech may lack meaning. They typically remain unaware of even their most profound language deficits.

<span class="mw-page-title-main">Broca's area</span> Speech production region in the dominant hemisphere of the hominid brain

Broca's area, or the Broca area, is a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions linked to speech production.

<span class="mw-page-title-main">Apraxia</span> Inability to perform purposeful movements

Apraxia is a motor disorder caused by damage to the brain, which causes difficulty with motor planning to perform tasks or movements. The nature of the damage determines the disorder's severity, and the absence of sensory loss or paralysis helps to explain the level of difficulty. Children may be born with apraxia; its cause is unknown, and symptoms are usually noticed in the early stages of development. Apraxia occurring later in life, known as acquired apraxia, is typically caused by traumatic brain injury, stroke, dementia, Alzheimer's disease, brain tumor, or other neurodegenerative disorders. The multiple types of apraxia are categorized by the specific ability and/or body part affected.

Aphasiology is the study of language impairment usually resulting from brain damage, due to neurovascular accident—hemorrhage, stroke—or associated with a variety of neurodegenerative diseases, including different types of dementia. These specific language deficits, termed aphasias, may be defined as impairments of language production or comprehension that cannot be attributed to trivial causes such as deafness or oral paralysis. A number of aphasias have been described, but two are best known: expressive aphasia and receptive aphasia.

Agraphia is an acquired neurological disorder causing a loss in the ability to communicate through writing, either due to some form of motor dysfunction or an inability to spell. The loss of writing ability may present with other language or neurological disorders; disorders appearing commonly with agraphia are alexia, aphasia, dysarthria, agnosia, acalculia and apraxia. The study of individuals with agraphia may provide more information about the pathways involved in writing, both language related and motoric. Agraphia cannot be directly treated, but individuals can learn techniques to help regain and rehabilitate some of their previous writing abilities. These techniques differ depending on the type of agraphia.

<span class="mw-page-title-main">Brain injury</span> Destruction or degeneration of brain cells

Brain injury (BI) is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors. In general, brain damage refers to significant, undiscriminating trauma-induced damage.

<span class="mw-page-title-main">Anomic aphasia</span> Medical condition

Anomic aphasia is a mild, fluent type of aphasia where individuals have word retrieval failures and cannot express the words they want to say. By contrast, anomia is a deficit of expressive language, and a symptom of all forms of aphasia, but patients whose primary deficit is word retrieval are diagnosed with anomic aphasia. Individuals with aphasia who display anomia can often describe an object in detail and maybe even use hand gestures to demonstrate how the object is used, but cannot find the appropriate word to name the object. Patients with anomic aphasia have relatively preserved speech fluency, repetition, comprehension, and grammatical speech.

<span class="mw-page-title-main">Wernicke's area</span> Speech comprehension region in the dominant hemisphere of the hominid brain

Wernicke's area, also called Wernicke's speech area, is one of the two parts of the cerebral cortex that are linked to speech, the other being Broca's area. It is involved in the comprehension of written and spoken language, in contrast to Broca's area, which is primarily involved in the production of language. It is traditionally thought to reside in Brodmann area 22, located in the superior temporal gyrus in the dominant cerebral hemisphere, which is the left hemisphere in about 95% of right-handed individuals and 70% of left-handed individuals.

<span class="mw-page-title-main">Conduction aphasia</span> Inability to repeat speech despite being able to perceive and produce it

In neurology, conduction aphasia, also called associative aphasia, is an uncommon form of difficulty in speaking (aphasia). It is caused by damage to the parietal lobe of the brain. An acquired language disorder, it is characterised by intact auditory comprehension, coherent speech production, but poor speech repetition. Affected people are fully capable of understanding what they are hearing, but fail to encode phonological information for production. This deficit is load-sensitive as the person shows significant difficulty repeating phrases, particularly as the phrases increase in length and complexity and as they stumble over words they are attempting to pronounce. People have frequent errors during spontaneous speech, such as substituting or transposing sounds. They are also aware of their errors and will show significant difficulty correcting them.

<span class="mw-page-title-main">Global aphasia</span> Medical condition

Global aphasia is a severe form of nonfluent aphasia, caused by damage to the left side of the brain, that affects receptive and expressive language skills as well as auditory and visual comprehension. Acquired impairments of communicative abilities are present across all language modalities, impacting language production, comprehension, and repetition. Patients with global aphasia may be able to verbalize a few short utterances and use non-word neologisms, but their overall production ability is limited. Their ability to repeat words, utterances, or phrases is also affected. Due to the preservation of the right hemisphere, an individual with global aphasia may still be able to express themselves through facial expressions, gestures, and intonation. This type of aphasia often results from a large lesion of the left perisylvian cortex. The lesion is caused by an occlusion of the left middle cerebral artery and is associated with damage to Broca's area, Wernicke's area, and insular regions which are associated with aspects of language.

Amusia is a musical disorder that appears mainly as a defect in processing pitch but also encompasses musical memory and recognition. Two main classifications of amusia exist: acquired amusia, which occurs as a result of brain damage, and congenital amusia, which results from a music-processing anomaly present since birth.

<span class="mw-page-title-main">Lateralization of brain function</span> Specialization of some cognitive functions in one side of the brain

The lateralization of brain function is the tendency for some neural functions or cognitive processes to be specialized to one side of the brain or the other. The median longitudinal fissure separates the human brain into two distinct cerebral hemispheres, connected by the corpus callosum. Although the macrostructure of the two hemispheres appears to be almost identical, different composition of neuronal networks allows for specialized function that is different in each hemisphere.

<span class="mw-page-title-main">Frontal lobe disorder</span> Brain disorder

Frontal lobe disorder, also frontal lobe syndrome, is an impairment of the frontal lobe of the brain due to disease or frontal lobe injury. The frontal lobe plays a key role in executive functions such as motivation, planning, social behaviour, and speech production. Frontal lobe syndrome can be caused by a range of conditions including head trauma, tumours, neurodegenerative diseases, neurodevelopmental disorders, neurosurgery and cerebrovascular disease. Frontal lobe impairment can be detected by recognition of typical signs and symptoms, use of simple screening tests, and specialist neurological testing.

<span class="mw-page-title-main">Foix–Chavany–Marie syndrome</span> Medical condition

Foix–Chavany–Marie syndrome (FCMS), also known as bilateral opercular syndrome, is a neuropathological disorder characterized by paralysis of the facial, tongue, pharynx, and masticatory muscles of the mouth that aid in chewing. The disorder is primarily caused by thrombotic and embolic strokes, which cause a deficiency of oxygen in the brain. As a result, bilateral lesions may form in the junctions between the frontal lobe and temporal lobe, the parietal lobe and cortical lobe, or the subcortical region of the brain. FCMS may also arise from defects existing at birth that may be inherited or nonhereditary. Symptoms of FCMS can be present in a person of any age and it is diagnosed using automatic-voluntary dissociation assessment, psycholinguistic testing, neuropsychological testing, and brain scanning. Treatment for FCMS depends on the onset, as well as on the severity of symptoms, and it involves a multidisciplinary approach.

Apraxia of speech (AOS), also called verbal apraxia, is a speech sound disorder affecting an individual's ability to translate conscious speech plans into motor plans, which results in limited and difficult speech ability. By the definition of apraxia, AOS affects volitional movement pattern. However, AOS usually also affects automatic speech.

<span class="mw-page-title-main">Sign language in the brain</span>

Sign language refers to any natural language which uses visual gestures produced by the hands and body language to express meaning. The brain's left side is the dominant side utilized for producing and understanding sign language, just as it is for speech. In 1861, Paul Broca studied patients with the ability to understand spoken languages but the inability to produce them. The damaged area was named Broca's area, and located in the left hemisphere’s inferior frontal gyrus. Soon after, in 1874, Carl Wernicke studied patients with the reverse deficits: patients could produce spoken language, but could not comprehend it. The damaged area was named Wernicke's area, and is located in the left hemisphere’s posterior superior temporal gyrus.

<span class="mw-page-title-main">Disconnection syndrome</span> Collection of neurological symptoms

Disconnection syndrome is a general term for a collection of neurological symptoms caused – via lesions to associational or commissural nerve fibres – by damage to the white matter axons of communication pathways in the cerebrum, independent of any lesions to the cortex. The behavioral effects of such disconnections are relatively predictable in adults. Disconnection syndromes usually reflect circumstances where regions A and B still have their functional specializations except in domains that depend on the interconnections between the two regions.

References

  1. Dronkers, Nina; Plaisant, O; Iba-Zizen, M. T.; Cabanis, E.A. (2007). "Paul Broca's historic cases: High resolution MR imaging of the brains of Leborgne and Lelong". Brain. 130 (Pt 5): 1432–1441. doi: 10.1093/brain/awm042 . PMID   17405763.
  2. Dronkers, Nina (1996). "A new brain region for speech: The insula and articulatory planning". Nature. 384 (6605): 159–161. doi:10.1038/384159a0. PMID   8906789. S2CID   4305696.
  3. Oliveria, R; Colaco, D; Tavares, J. B.; Lauterbach, M (2020). "Focal lesion in Dronkers' area associated with developmental apraxia of speech". Neurol Sci. 41 (4): 965–966. doi:10.1007/s10072-019-04097-7. PMID   31673958. S2CID   204971853.
  4. Giannecchini, T; Yucubian-Fernandes, A; Maximo, L. P. (2016). "Nonverbal praxis in speech pathology: Literature review". Revista CEFAC. 18: 1200–1208. doi: 10.1590/1982-021620161856816 .
  5. Bates, E; Wilson, S.M.; Saygin, A.P.; Dick, F.; Sereno, M.; Knight, R.T.; Dronkers, N.F. (2003). "Voxel-based lesion-symptom mapping". Nature Neuroscience. 6 (5): 448–450. doi:10.1038/nn1050. PMID   12704393. S2CID   5134480.