Edward Chang (neurosurgeon)

Last updated
Edward Chang
Born
Edward F. Chang
Alma mater University of California, San Francisco
Known forNeurosurgery
Scientific career
Fields Neuroscience
InstitutionsDepartment of Neurological Surgery at the University of California, San Francisco

Edward Chang is an American neurosurgeon and scientist. He is the Joan and Sandy Weill Chair of the Department of Neurological Surgery at the University of California, San Francisco and Jeanne Robertson Distinguished Professor.

Contents

Chang specializes in operative brain mapping to ensure the safety and effectiveness of surgery for treating seizures and brain tumors, as well as micro-neurosurgery for treating cranial nerve disorders such as trigeminal neuralgia and hemifacial spasm. In 2020, Chang was elected into the National Academy of Medicine [1] for “deciphering the functional blueprint of speech in the human cerebral cortex, pioneering advanced clinical methods for human brain mapping and spearheading novel translational neuroprosthetic technology for paralyzed patients.” [2] [3]

Academic career

Chang attended medical school at UCSF, where he also did a predoctoral fellowship on auditory cortex neurophysiology with Professor Michael Merzenich. He later did his neurosurgery residency at UCSF and trained under the mentorship of Dr. Mitchel Berger for brain tumors, Dr. Nicholas Barbaro for epilepsy, and Dr. Michael Lawton for vascular disorders. During residency, he did postdoctoral fellowship on human cognitive neuroscience with Dr. Robert Knight at UC Berkeley. [4]

Chang joined the UCSF neurosurgery faculty in 2010 and was promoted to department chair in 2020. [4]

Scientific contributions

Chang has made fundamental contributions to understanding the neural code of speech and neuropsychiatric conditions in the human brain. [5]

Chang pioneered the use of high-density direct electrophysiological recordings from cortex, which enabled him and colleagues to determine the selective tuning of cortical neurons to specific acoustic and phonetic features in consonants and vowels. [6] His lab discovered the neural coding of vocal pitch cues in prosodic intonation for English and lexical tones in Mandarin. [7] Chang's lab determined how the auditory cortex detects temporal landmarks such as onsets and acoustic edges in the speech envelope signal to extract syllables and stress patterns, [8] important for the rhythm and intelligibility of speech.

A general finding in his work is that the internal phonological representation of speech sounds results from complex auditory computations in the STG; including processes such as adaptation, contrast enhancement, normalization, complex spectral integration, non-linear processing, prediction and temporal dynamics. [9]

His lab demonstrated that the superior temporal lobe is critical for conscious speech perception. That is, it is not only integral for detecting speech sounds but also interpreting them. For example, they showed how the superior temporal cortex can selectively attend to one voice when multiple voices are present [10] and how it restores missing sounds to words when a phoneme segment is replaced with noise. [11]

To address information flow in auditory speech processing, Chang and his colleagues demonstrated that the primary auditory cortex may not be a critical input to phonological processing in the STG. They showed that both primary and non-primary STG areas are activated in parallel, and that interruption of the primary auditory cortex through electrical stimulation and ablation does not have significant consequences on auditory word recognition. [12] Conversely, interruption of the left STG does impair auditory word recognition. Instead of serial feedforward processing in the classic ventral stream model, they propose an alternative model where inputs may be thalamic in origin, auditory word processing is mediated by recurrent processing in the STG, and that word representations emerge from the time-dependent population dynamics of STG neurons. [13]

Chang's lab also studies the basis of speech production, the neurobiological mechanisms that govern how we speak. He and his colleagues have mapped out how different locations of the sensorimotor cortex control specific movements of the vocal tract, including the lips, jaw, tongue and larynx. [14] With cortical recordings and electrical stimulation mapping, Chang demonstrated the existence of dual laryngeal motor representations on each hemisphere. [15] This finding revised the long-held "homunculus" functional organization of human motor cortex. The dorsal laryngeal cortex is a region that is responsible for controlling the intonational pitch of one's voice when speaking, and when stimulated, can evoke vocalization. It has been proposed that this area may have been critical to the evolution of speech in humans. [16]

Chang has proposed that the middle precentral gyrus is an important area for speech planning for articulation, a function that has been traditionally attributed to Broca’s area in the posterior inferior frontal gyrus. [17] This novel brain area overlaps with the dorsal larynx cortex, and has unique integrative functions including auditory processing [18] and reading and spelling. He demonstrated that surgical resection of a tumor in the left precentral gyrus can result in apraxia of speech, a condition where articulatory speech fluency is affected, despite normal language functions and intact orofacial motor strength. [19] In contrast, resections in Broca's area can cause word finding difficulties, but rarely result in dysfluency of Broca's aphasia. [20]

Chang's team applied their discoveries on speech control to develop new neuroprosthetic technology designed to restore communication to patients who have lost the ability to speak. In 2019, they demonstrated that is possible to synthesize intelligible speech sentences from cortical recordings of brain activity. [21] In 2021, as part of the BRAVO clinical trial, the team demonstrated the first successful decoding of full words and sentences from the brain activity of a man who was severely paralyzed after brainstem stroke and could not speak for over 15 years. [2] They subsequently expanded this approach to demonstrate the first successful speech synthesis and control over a digital facial avatar, as well as large-vocabulary, high-performance text decoding. [22] [23]

Chang has also done research to understand and treat neuropsychiatric conditions such as depression and chronic pain. From 2014-2019, Chang led a multi-institutional project in the US BRAIN Initiative, which focused on developing new medical device technology to treat severe refractory neuropsychiatric conditions. [24] He and colleagues developed new methods to record and precisely stimulate focal brain regions to alleviate depression and anxiety, [25] as well as methods to detect and monitor depression symptoms from brain activity. [26]

In 2021, as part of a FDA approved clinical trial, they demonstrated the first successful application of closed-loop deep brain stimulation for the treatment of depression, in which focal precise stimulation is applied episodically when brain recordings detected depression states. [27] In 2023, Prasad Shirvalkar, a pain neurologist at UCSF, and Chang demonstrated the direct brain activity patterns that predict chronic pain. [28]

Awards

2023Winn PrizeSociety of Neurological Surgeons
2022Pradel Award [29] National Academy of Sciences
2020National Academy of MedicineNational Academies
2018Bowes Biomedical InvestigatorWilliam K Bowes Foundation
2015Blavatnik National Laureate in Life SciencesThe Blavatnik Family Foundation
2015Robertson InvestigatorNew York Stem Cell Foundation
2014McKnight Memory and Cognitive Disorders AwardThe McKnight Endowment Fund for Neuroscience
2011NIH Director's New Innovator Award (DP2)National Institutes of Health (NIH)
2011Klingenstein Fellowship Award in the Neurosciences,  Ebert ScholarThe Ester A. and Joseph Klingenstein Foundation
2009Pathway to Independence AwardK99/R00 NIH NINDS
2009Ronald Bittner AwardAmerican Association of Neurological Surgeons
2008Wilder Penfield FellowshipCongress of Neurological Surgeons (CNS)

Related Research Articles

<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">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">Brodmann area</span> 52 distinct regions of the brains cerebral cortex

A Brodmann area is a region of the cerebral cortex, in the human or other primate brain, defined by its cytoarchitecture, or histological structure and organization of cells. The concept was first introduced by the German anatomist Korbinian Brodmann in the early 20th century. Brodmann mapped the human brain based on the varied cellular structure across the cortex and identified 52 distinct regions, which he numbered 1 to 52. These regions, or Brodmann areas, correspond with diverse functions including sensation, motor control, and cognition.

<span class="mw-page-title-main">Temporal lobe</span> One of the four lobes of the mammalian brain

The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain.

<span class="mw-page-title-main">Brodmann area 44</span> Brain area

Brodmann area 44, or BA44, is part of the frontal cortex in the human brain. Situated just anterior to premotor cortex (BA6) and on the lateral surface, inferior to BA9.

<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, which is 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">Inferior frontal gyrus</span> Part of the brains prefrontal cortex

The inferior frontal gyrus (IFG),, is the lowest positioned gyrus of the frontal gyri, of the frontal lobe, and is part of the prefrontal cortex.

<span class="mw-page-title-main">Auditory cortex</span> Part of the temporal lobe of the brain

The auditory cortex is the part of the temporal lobe that processes auditory information in humans and many other vertebrates. It is a part of the auditory system, performing basic and higher functions in hearing, such as possible relations to language switching. It is located bilaterally, roughly at the upper sides of the temporal lobes – in humans, curving down and onto the medial surface, on the superior temporal plane, within the lateral sulcus and comprising parts of the transverse temporal gyri, and the superior temporal gyrus, including the planum polare and planum temporale.

<span class="mw-page-title-main">Transverse temporal gyrus</span> Gyrus of the primary auditory cortex of the brain

The transverse temporal gyri, also called Heschl's gyri or Heschl's convolutions, are gyri found in the area of primary auditory cortex buried within the lateral sulcus of the human brain, occupying Brodmann areas 41 and 42. Transverse temporal gyri are superior to and separated from the planum temporale by Heschl's sulcus. Transverse temporal gyri are found in varying numbers in both the right and left hemispheres of the brain and one study found that this number is not related to the hemisphere or dominance of hemisphere studied in subjects. Transverse temporal gyri can be viewed in the sagittal plane as either an omega shape or a heart shape.

<span class="mw-page-title-main">Superior temporal gyrus</span> One of three gyri of the temporal lobe of the brain

The superior temporal gyrus (STG) is one of three gyri in the temporal lobe of the human brain, which is located laterally to the head, situated somewhat above the external ear.

<span class="mw-page-title-main">Language processing in the brain</span> How humans use words to communicate

In psycholinguistics, language processing refers to the way humans use words to communicate ideas and feelings, and how such communications are processed and understood. Language processing is considered to be a uniquely human ability that is not produced with the same grammatical understanding or systematicity in even human's closest primate relatives.

<span class="mw-page-title-main">Gyrus</span> Ridge on the cerebral cortex of the brain

In neuroanatomy, a gyrus is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci. Gyri and sulci create the folded appearance of the brain in humans and other mammals.

<span class="mw-page-title-main">Brodmann area 22</span> Region of the brains temporal lobe

Brodmann area 22 is a Brodmann's area that is cytoarchitecturally located in the posterior superior temporal gyrus of the brain. In the left cerebral hemisphere, it is one portion of Wernicke's area. The left hemisphere BA22 helps with generation and understanding of individual words. On the right side of the brain, BA22 helps to discriminate pitch and sound intensity, both of which are necessary to perceive melody and prosody. Wernicke's area is active in processing language and consists of the left Brodmann area 22 and Brodmann area 40, the supramarginal gyrus.

<span class="mw-page-title-main">Frontal gyri</span> Four gyri of the frontal lobe in the brain

The frontal gyri are six gyri of the frontal lobe in the brain. There are five horizontally oriented, parallel convolutions, of the frontal lobe that are aligned anterior to posterior. Three are visible on the lateral surface of the brain and two are on the inferior surface of the frontal lobe in a region called orbitofrontal cortex. The other main gyrus of the frontal lobe is the precentral gyrus which is vertically oriented, and runs parallel with the precentral sulcus.

Auditory agnosia is a form of agnosia that manifests itself primarily in the inability to recognize or differentiate between sounds. It is not a defect of the ear or "hearing", but rather a neurological inability of the brain to process sound meaning. While auditory agnosia impairs the understanding of sounds, other abilities such as reading, writing, and speaking are not hindered. It is caused by bilateral damage to the anterior superior temporal gyrus, which is part of the auditory pathway responsible for sound recognition, the auditory "what" pathway.

<span class="mw-page-title-main">Superior temporal sulcus</span> Part of the brains temporal lobe

In the human brain, the superior temporal sulcus (STS) is the sulcus separating the superior temporal gyrus from the middle temporal gyrus in the temporal lobe of the brain. A sulcus is a deep groove that curves into the largest part of the brain, the cerebrum, and a gyrus is a ridge that curves outward of the cerebrum.

Cortical stimulation mapping (CSM) is a type of electrocorticography that involves a physically invasive procedure and aims to localize the function of specific brain regions through direct electrical stimulation of the cerebral cortex. It remains one of the earliest methods of analyzing the brain and has allowed researchers to study the relationship between cortical structure and systemic function. Cortical stimulation mapping is used for a number of clinical and therapeutic applications, and remains the preferred method for the pre-surgical mapping of the motor cortex and language areas to prevent unnecessary functional damage. There are also some clinical applications for cortical stimulation mapping, such as the treatment of epilepsy.

The temporal dynamics of music and language describes how the brain coordinates its different regions to process musical and vocal sounds. Both music and language feature rhythmic and melodic structure. Both employ a finite set of basic elements that are combined in ordered ways to create complete musical or lingual ideas.

<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">Auditosensory cortex</span>

The auditosensory cortex is the part of the auditory system that is associated with the sense of hearing in humans. It occupies the bilateral primary auditory cortex in the temporal lobe of the mammalian brain. The term is used to describe Brodmann areas 41 and 42 together with the transverse temporal gyrus. The auditosensory cortex takes part in the reception and processing of auditory nerve impulses, which passes sound information from the thalamus to the brain. Abnormalities in this region are responsible for many disorders in auditory abilities, such as congenital deafness, true cortical deafness, primary progressive aphasia and auditory hallucination.

References

  1. ↑ "National Academy of Medicine Elects 100 New Members". October 19, 2020.
  2. 1 2 Belluck, Pam (2021-07-14). "Tapping Into the Brain to Help a Paralyzed Man Speak". The New York Times. ISSN   0362-4331 . Retrieved 2021-07-22.
  3. ↑ Willingham, Emily. "New Brain Implant Transmits Full Words from Neural Signals". Scientific American.
  4. 1 2 "Edward Chang, MD, Appointed Joan and Sanford I. Weill Chair of Department of Neurological Surgery". UCSF School of Medicine. Retrieved 2023-06-19.
  5. ↑ Hernandez, Daniela (2022-09-02). "How Brain-Computer Interfaces Could Restore Speech and Help Fight Depression". Wall Street Journal. ISSN   0099-9660 . Retrieved 2023-07-19.
  6. ↑ "Researchers Watch As Our Brains Turn Sounds Into Words". NPR.
  7. ↑ "Really? Really. How Our Brains Figure Out What Words Mean Based On How They're Said". NPR.
  8. ↑ "The Loudness Of Vowels Helps The Brain Break Down Speech Into Syl-La-Bles". NPR.
  9. ↑ Bhaya-Grossman, Ilina; Chang, Edward F. (2022-01-04). "Speech Computations of the Human Superior Temporal Gyrus". Annual Review of Psychology. 73 (1): 79–102. doi:10.1146/annurev-psych-022321-035256. ISSN   0066-4308. PMC   9447996 . PMID   34672685.
  10. ↑ Beck, Melinda (2012-04-23). "What Cocktail Parties Teach Us". Wall Street Journal. ISSN   0099-9660 . Retrieved 2023-07-19.
  11. ↑ "Your brain fills gaps in your hearing without you realising". New Scientist. Retrieved 2023-07-19.
  12. ↑ "The Brain Processes Speech in Parallel With Other Sounds".
  13. ↑ Bhaya-Grossman, Ilina; Chang, Edward F. (2022-01-04). "Speech Computations of the Human Superior Temporal Gyrus". Annual Review of Psychology. 73 (1): 79–102. doi:10.1146/annurev-psych-022321-035256. ISSN   0066-4308. PMC   9447996 . PMID   34672685.
  14. ↑ Bouchard, Kristofer E.; Mesgarani, Nima; Johnson, Keith; Chang, Edward F. (2013). "Functional organization of human sensorimotor cortex for speech articulation". Nature. 495 (7441): 327–332. doi:10.1038/nature11911. ISSN   1476-4687. PMC   3606666 . PMID   23426266.
  15. ↑ "One Sentence With 7 Meanings Unlocks a Mystery of Human Speech". Wired. ISSN   1059-1028.
  16. ↑ Jarvis, Erich D. (2019-10-04). "Evolution of vocal learning and spoken language". Science. 366 (6461): 50–54. doi: 10.1126/science.aax0287 . ISSN   0036-8075.
  17. ↑ Silva, Alexander B.; Liu, Jessie R.; Zhao, Lingyun; Levy, Deborah F.; Scott, Terri L.; Chang, Edward F. (2022-11-09). "A Neurosurgical Functional Dissection of the Middle Precentral Gyrus during Speech Production". Journal of Neuroscience. 42 (45): 8416–8426. doi: 10.1523/JNEUROSCI.1614-22.2022 . ISSN   0270-6474. PMC   9665919 . PMID   36351829.
  18. ↑ Cheung, C.; Hamilton, L. S.; Johnson, K.; Chang, E. F. (2016-03-04). Shinn-Cunningham, Barbara G (ed.). "The auditory representation of speech sounds in human motor cortex". eLife. 5: e12577. doi: 10.7554/eLife.12577 . ISSN   2050-084X. PMC   4786411 . PMID   26943778.
  19. ↑ Levy, Deborah F.; Silva, Alexander B.; Scott, Terri L.; Liu, Jessie R.; Harper, Sarah; Zhao, Lingyun; Hullett, Patrick W.; Kurteff, Garret; Wilson, Stephen M.; Leonard, Matthew K.; Chang, Edward F. (2023-03-27). "Apraxia of speech with phonological alexia and agraphia following resection of the left middle precentral gyrus: illustrative case". Journal of Neurosurgery: Case Lessons. 5 (13). doi: 10.3171/CASE22504 .
  20. ↑ Andrews, John P.; Cahn, Nathan; Speidel, Benjamin A.; Chung, Jason E.; Levy, Deborah F.; Wilson, Stephen M.; Berger, Mitchel S.; Chang, Edward F. (2022-08-05). "Dissociation of Broca's area from Broca's aphasia in patients undergoing neurosurgical resections". Journal of Neurosurgery. 138 (3): 847–857. doi:10.3171/2022.6.JNS2297. ISSN   1933-0693. PMC   9899289 . PMID   35932264.
  21. ↑ Carey, Benedict (2019-04-24). "Scientists Create Speech From Brain Signals". The New York Times. ISSN   0362-4331.
  22. ↑ Metzger, Sean L.; Littlejohn, Kaylo T.; Silva, Alexander B.; Moses, David A.; Seaton, Margaret P.; Wang, Ran; Dougherty, Maximilian E.; Liu, Jessie R.; Wu, Peter; Berger, Michael A.; Zhuravleva, Inga; Tu-Chan, Adelyn; Ganguly, Karunesh; Anumanchipalli, Gopala K.; Chang, Edward F. (2023). "A high-performance neuroprosthesis for speech decoding and avatar control". Nature. 620 (7976): 1037–1046. doi:10.1038/s41586-023-06443-4. PMC   10826467 . PMID   37612505.
  23. ↑ "AI Helps a Stroke Patient Speak Again, a Milestone for Tech and Neuroscience".
  24. ↑ Reardon, Sara (2015-06-01). "The Pentagon's gamble on brain implants, bionic limbs and combat exoskeletons". Nature. 522 (7555): 142–144. doi: 10.1038/522142a . ISSN   1476-4687.
  25. ↑ "Researchers Uncover A Circuit For Sadness In The Human Brain". NPR.
  26. ↑ Hernandez, Daniela (2018-09-10). "Brain Data Could Read Moods, Potentially Treat Depression". Wall Street Journal. ISSN   0099-9660 . Retrieved 2023-07-19.
  27. ↑ Belluck, Pam (2021-10-04). "A 'Pacemaker for the Brain': No Treatment Helped Her Depression — Until This". The New York Times. ISSN   0362-4331 . Retrieved 2023-07-19.
  28. ↑ Runwal, Priyanka (2023-05-22). "Scientists Find Brain Signals of Chronic Pain". The New York Times. ISSN   0362-4331 . Retrieved 2023-07-19.
  29. ↑ "2022 NAS Awards Recipients Announced".
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