Podcast Summary
Neurosurgeon Eddie Chang discusses brain function, speech, and language: Renowned neurosurgeon Eddie Chang shares insights on movement disorders, epilepsy, speech disorders, and future brain augmentation technologies, based on his research at UCSF.
Eddie Chang, a world-renowned neurosurgeon and researcher at the University of California, San Francisco. Dr. Chang's work focuses on movement disorders, epilepsy, and speech disorders, including those that result in fully locked-in syndrome. He is also a leader in bioengineering, creating devices that allow the brain to function at super physiological levels and help individuals with various syndromes and disorders overcome their deficits. The discussion covered various aspects of speech and language, the brain's control of movement, critical periods for learning, and even the future of brain augmentation technologies. Dr. Chang's personal journey with his longtime friend and podcast host, Andrew Huberman, added an interesting and unique perspective to the conversation. Overall, this episode offers valuable insights into the workings of the brain, communication, and the potential for repair and enhancement.
The sounds we hear during critical periods of brain development shape our auditory system: Exposure to specific sounds during sensitive brain development periods can influence the organization of the auditory cortex, potentially shaping our speech and hearing abilities in the future.
Our environment, specifically the sounds we're exposed to during critical periods of brain development, can significantly impact the structure and function of our auditory system. During this sensitive period, the brain is highly susceptible to the patterns of sounds it encounters, and these experiences can influence the organization of the auditory cortex. For instance, research conducted on rodents revealed that exposing them to continuous white noise during this critical period can keep the window for plasticity open for longer periods, but it can also delay the maturation of the auditory cortex. This finding suggests that the nature of the sounds we hear can shape our brain development in profound ways, potentially influencing how we speak and hear in the future. Furthermore, the sounds we're exposed to even before birth can impact neural network development, and ongoing research suggests that the sounds we encounter throughout our lives continue to influence how we process and perceive speech and languages. Regarding the use of white noise machines during sleep, more research is needed to determine if and how they might affect brain development in infants. However, the findings from animal studies highlight the importance of considering the role of environmental sounds in shaping our auditory system and, by extension, our overall cognitive development.
White noise's impact on baby's brain development: Continuous white noise exposure may slow down brain development, particularly in the auditory cortex, affecting speech. Replace it with natural sounds to improve brain development.
While white noise generators can help soothe babies to sleep, there may be potential negative effects on their brain development, particularly in the auditory cortex. Studies on rodents suggest that continuous exposure to white noise can slow down the maturation of this area of the brain, which could impact speech development. The goal should be to replace white noise with more natural, structured sounds that can help improve the signal-to-noise ratio in the brain and support healthy development. It's important to note that the impact of white noise on speech and language development in humans is not yet clear, and more research is needed. In neurobiology, speech and language are related but distinct processes. Speech refers to the physical production of sounds, while language involves the understanding and use of symbols and rules to communicate. Different brain areas are involved in controlling these functions, with the motor cortex and basal ganglia playing key roles in speech production, and the temporal lobes and prefrontal cortex involved in language processing. Understanding the relationship between speech, language, and hearing, as well as the role of emotions and gestures, is an active area of research in neuroscience.
Exploring the brain's plasticity and language areas during surgery: Observing brain surgeries and researching plasticity revealed the importance of preserving language areas, as stimulating certain regions can temporarily disrupt speech and demonstrate the brain's complex role in generating language.
The brain's plasticity and its representation of sound through brain activity are crucial concepts that shaped my medical career. Witnessing Mike Mersnick's research on plasticity and observing awake brain surgeries, where patients communicate with neuropsychologists while undergoing surgery, highlighted the importance of preserving language areas during brain tumor removal or seizure control. This process, known as brain mapping, involves probing different brain areas using a small electrical stimulator to determine which regions are safe to manipulate. Stimulating certain areas can temporarily shut down speech, demonstrating the brain's role in generating language and emphasizing its unique complexity. Emotional responses or specific types of speech, such as curse words, can also be associated with certain brain areas. The ability to physically alter the brain's function during surgery and observe the resulting changes is a constant reminder of the brain's remarkable capabilities.
Emotions and Brain Functions: Understanding the connections between emotions, language, and the brain can reveal insights into mental health and treatment options, including epilepsy where uncontrollable brain activity causes seizures, requiring invasive measures or neurosurgery for diagnosis and treatment.
Certain words and brain areas have the ability to evoke strong emotional responses. For instance, stimulating the orbital frontal cortex can reduce stress, while stimulating areas like the amygdala or insula can cause anxiety or feelings of disgust. The brain's complex functions and different nodes help process emotions, and imbalances in these areas can lead to neuropsychiatric conditions. One such condition, epilepsy, can cause uncontrollable electrical activity in the brain, leading to seizures that can be difficult to diagnose without invasive measures like electrode implantation. While there are drugs for epilepsy, their effectiveness varies, and neurosurgery may be necessary for some cases. Understanding the connections between emotions, language, and the brain can provide valuable insights into mental health and treatment options.
Exploring Alternative Solutions for Epilepsy: For one-third of individuals with epilepsy, medication is not effective. Surgery, including brain stimulation, and the ketogenic diet are alternative solutions to consider.
While medications can effectively control seizures for many people with epilepsy, about one-third of individuals with the condition do not respond to multiple medications. For this group, surgery, including brain stimulation, may offer a solution. The ketogenic diet, which was originally developed to treat epilepsy, can also be beneficial for some people, although the reasons for its effectiveness are not fully understood. Epilepsy is complex, and its causes and treatments vary widely. Some cases involve seizures originating in a specific area of the brain, which can be treated with surgery. Other cases involve seizures arising from multiple areas or the entire brain, requiring different approaches. Probiotics, like those found in Athletic Greens, can support gut health and, in turn, overall health. For individuals with epilepsy, finding the right treatment involves persistence and exploration of various options.
Types of Seizures and Their Effects: Seizures can manifest differently depending on their location and time in the brain, causing various symptoms from loss of consciousness to unusual sensory experiences, even during sleep. Recent research challenges our understanding of speech and language functions in the brain.
Seizures, a common symptom of epilepsy, can manifest in various ways depending on where and when they occur in the brain. Absence seizures, for instance, cause temporary loss of consciousness without convulsions, and can go unnoticed by others. Temporal lobe seizures, on the other hand, can lead to unusual sensory experiences like metallic tastes or deja vu. Nocturnal seizures, as the name suggests, occur during sleep. The brain areas responsible for speech and language are well-studied, with Broca's area linked to production and Wernicke's area to comprehension. However, recent research suggests that our understanding of these functions may be more complex than previously thought.
The Complex Relationship Between Language and the Brain: Early theories about language and the brain were oversimplified, but the relationship is more complex than Broca and Wernicke's discoveries suggest.
The relationship between language and the brain has been a topic of controversy and discovery for centuries. Early theories, such as phrenology, suggested that the bumps on the head corresponded to different faculties of the mind. However, these ideas were debunked as neuroscience progressed and the focus shifted to the brain itself. A significant discovery in this field was made by French neurosurgeon Pierre Broca, who observed a patient named Tan who could only utter the word "tan." Broca identified the seat of articulation in the left frontal lobe of the brain. Later, German neurologist Karl Wernicke identified a different area, the left temporal lobe, as crucial for understanding language. However, the speaker's personal experience of caring for patients with brain injuries challenged the simplistic understanding of language functions based on Broca and Wernicke's discoveries. The reality was more complex, and the idea that language functions could be neatly divided into two areas was fundamentally wrong. Despite this, the textbooks and teachings continue to present this oversimplified view. The speaker encourages us to question this oversimplification and to recognize the complexity of the relationship between language and the brain.
The Role of Broca's and Wernicke's Areas in Language is Evolving: New research challenges the traditional view of Broca's and Wernicke's areas as the sole basis for speaking and comprehension, respectively. The brain's role in language is complex and still largely a mystery.
Our understanding of the brain and its role in language, specifically the areas of Broca's and Wernicke's, is still evolving and complex. While it was once believed that Broca's area was the sole basis for speaking, new research suggests that the pre-central gyrus, a part of the motor cortex, also plays a crucial role in language production. Conversely, Wernicke's area in the posterior temporal lobe has been accepted as the essential area for language comprehension and expression. However, the brain is still largely a mystery, and much of what we learn in medical and graduate school is an approximation or oversimplification. Language, for instance, is heavily lateralized to the left side of the brain, but the function of the equivalent structures on the right side remains unclear. As we continue to explore the brain and make technical advances, our understanding of these areas and their roles will likely evolve, and previous assumptions may be revised. It's important to remember that the field of neuroscience is constantly evolving, and our knowledge is incomplete, but we are making progress.
Brain's language capabilities in right-handers: Handedness influences brain's language location, but both sides have potential to develop language capabilities, and we utilize one side for efficient communication.
While the left side of the brain is predominantly associated with language for right-handed individuals, the right side of the brain shares a similar structure and has the potential to develop language capabilities. Handedness, which has a strong genetic component, influences the location of language in the brain due to the proximity of hand control areas and language areas. However, the brain specializes one side for functional use in everyday life, even for bilingual individuals who may use different sides for different languages. The brain likely has similar machinery for language processing on both sides, but we only utilize one side at a time for efficient communication.
Understanding the Complexity of Bilingual Brain Language Processing: Bilingual individuals have intricate brain functions for language processing, with speech and language areas overlapping but varying in interpretation. Research focuses on how the brain processes speech as a form of language, revealing fascinating complexities.
The brain processes language in a complex and interconnected way, especially in bilingual individuals. Brain activity for different languages can overlap significantly, but the processing and interpretation can vary. The brain areas involved in language processing, such as those responsible for speech and language, have intricate functions. Speech refers to the physical act of producing and hearing words, while language encompasses the meaning and context behind them. Research focuses on understanding how the brain processes speech as a form of language, breaking down the sound vibrations into different frequencies. The brain's ability to process language is fascinating and complex, with ongoing research shedding new light on this essential human capability.
Understanding the Brain's Complex Processing of Speech Sounds: Research using electrodes reveals intricate brain activity patterns for processing speech sounds, allowing us to understand language areas, protect them during surgery, and gain insights into neural mechanisms.
Our ears are incredibly precise in separating and processing different sounds, breaking them down into various frequencies. The brain then analyzes these frequencies, specifically focusing on human language sounds in the cortex. Research using electrodes directly recording from the human brain surface has revealed intricate patterns of activity in response to words and sentences. These patterns can be deciphered to understand which individual sites in the brain are responsible for processing specific consonants, vowels, or emotionality in speech. Some sites are even tuned to particular features of consonants, such as plosive consonants which require mouth closure. This complex process allows us to understand the direction of sounds, protect language areas during surgery, and gain insights into the neural mechanisms of speech processing.
The Intricacy of Human Speech Production: Speech is a complex motor act involving the larynx, vocal folds, and various structures in the vocal tract to shape breath and create sounds. The neural structures underlying this process are complex, with differences contributing to unique vocal qualities.
Speaking is a complex motor act that involves the coordination of various structures in the vocal tract, including the larynx and pharynx, to shape breath and create sounds. The larynx, specifically, brings the vocal folds together when we exhale, causing them to vibrate and produce sound. This sound then travels up through the vocal tract, where the tongue, lips, and other structures shape the air into consonants and vowels, creating words. This process is so intricate that we can produce vocalizations, like crying or laughter, even with injuries to the speech and language areas of the brain. These vocalizations involve the same basic mechanism of expelling air and creating sound at the level of the larynx, but they are produced by different areas of the brain. The neural structures underlying speech and language are incredibly complex, but researchers are beginning to uncover some general principles and features. For instance, the size and shape of the larynx contribute to the different vocal frequencies and qualities in male and female voices. This intricate system of vocal production is a testament to the incredible complexity of human communication.
The organization of language in the brain follows a systematic layout similar to the sensory systems for sound and vision.: Research shows that the brain's language areas follow a complex and orderly pattern, with distinct representations for different sounds and speech features. This understanding of neural organization can aid in language processing, learning, therapy, and technology.
The organization of the brain, particularly in areas like Heschl's gyrus and Broca's area, follows a systematic layout similar to that of the sensory systems for sound and vision. For instance, in the auditory system, different sound frequencies are represented in a systematic and orderly manner in the primary auditory cortex. This map of sound frequencies is important for speech processing, and there is evidence that speech can bypass the primary auditory cortex and go directly to the speech processing areas. However, the organization of language in the brain is not universally consistent across individuals. It is more like a "salt and pepper" map of different features of speech. For example, plosive and fricative sounds, which are created by different methods in the oral cavity, have distinct representations in the brain. Additionally, certain words or sounds, such as "phthalates," which contain a combination of plosive and fricative sounds, can be more difficult to pronounce due to the complex consonant clusters they contain. Languages also vary in the number and complexity of consonant clusters they use. Overall, the organization of language in the brain is a complex and fascinating area of study, with many questions still to be answered. Understanding these underlying neural representations can provide insights into language processing and learning, as well as potential applications in fields such as speech therapy and language technology.
Brain's sensitivity to speech sounds during development: Early and intensive language exposure before age 12 is crucial for bilingualism without an accent due to the brain's sensitivity to speech sounds during development.
The earlier and more intensive exposure to multiple languages during development, ideally before age 12, is crucial for becoming bilingual without an accent. This is due to the brain's sensitivity to speech sounds during this period, which can be easily lost if not maintained. The brain's representation of language, particularly consonants, maps to motor structures related to pronunciation. The complexity of language, both in understanding and generating, is linked to its motor design. Moreover, reading and writing, though human inventions, are not entirely separate from speech and language. They utilize existing brain areas, such as the visual word form area in the back of the temporal lobe. The brain adapts to specialized behaviors by reallocating resources from other functions. The sounds of speech are made up of approximately 12 distinct articulatory features, such as tongue, jaw, and lip movements. These features, when combined and sequenced, generate all possible words in a language. This is akin to DNA's four base pairs generating the code for life. In essence, language, both spoken and written, is a fundamental aspect of human existence, hardwired into our brains. Reading and writing are additions to this architecture, utilizing existing brain areas for specialized purposes.
The connection between speech and reading: People with dyslexia may struggle to map reading signals to the auditory speech cortex, making it essential to address both visual and auditory aspects for effective reading interventions.
Reading and writing are not just visual activities, but they also involve the processing of speech sounds in the brain. This connection is particularly important when it comes to learning to read and understanding conditions like dyslexia. The brain's auditory speech cortex is the fundamental area for speech processing, and when we learn to read, our brains try to map those reading signals to this area. For some individuals with dyslexia, this mapping process is different, leading to difficulty in recognizing the sounds of words when reading. Current treatments for dyslexia often focus on improving phonological awareness, which is the ability to recognize and manipulate the sounds of spoken language. However, recent research suggests that interventions that address both the visual and auditory aspects of reading may be more effective. Overall, understanding the interconnected nature of speech and reading can provide valuable insights into learning processes and the development of effective interventions for reading difficulties.
The Connection Between Listening and Speaking: Our auditory and speech production areas are linked, influencing how we speak. Languages and speech evolve, with dialects and new languages emerging. While learning new languages is possible, spontaneous language acquisition after a brain injury is rare. Auditory memory allows us to remember sounds and voices long after the original experience.
The way we consume information, whether through reading or listening, can influence how we speak. Our auditory and speech production areas are interconnected, and the sounds we hear can shape our speech patterns. Contrary to popular belief, languages and speech evolve constantly, with dialects and new languages emerging over time. While it's possible to learn new languages throughout our lives, stories of spontaneously gaining the ability to speak a new language after a brain injury are largely implausible. Instead, there is a condition called Foreign Accent Syndrome, where individuals adopt some phonological features of a language after a stroke, even if they don't understand the meaning or grammar. Auditory memory is another fascinating aspect of language, as we can remember sounds and voices long after the original experience. The location and structure of auditory memory are still subjects of ongoing research.
The brain's distributed nature allows for fluency in language and retention of memories despite injuries.: Research shows that language fluency and memory retention are distributed across multiple brain areas, enabling us to speak our native language after long absences and for brain injury patients to retain certain skills.
Memory and the ability to speak are not localized in one specific area of the brain, but rather are distributed across multiple areas. This was discussed in relation to the speaker's ability to fluently speak their native language, even after a long time, and the impressive ability of patients with brain injuries to retain certain memories and motor skills. The speaker also highlighted their own research in helping paralyzed individuals communicate using brain-machine interfaces, which involves decoding neural activity in the brain and translating it into speech. This research has been successful in allowing paralyzed individuals to communicate through text or speech output, but more recently, the focus has shifted to making these interactions more elaborate and realistic in the real world. The speaker expressed their excitement about this recent work and the potential it holds for improving the lives of those who are paralyzed or unable to communicate in traditional ways.
Living with Devastating Forms of Paralysis: Locked-in Syndrome: Despite the challenges of living with devastating forms of paralysis like locked-in syndrome, research offers hope through technology that intercepts and translates brain signals into words.
Paralysis can take various forms, some of which are particularly devastating. For instance, brainstem strokes can leave individuals with fully functioning minds but an inability to communicate or move. Neurodegenerative conditions like ALS can result in a complete loss of voluntary movement, including the muscles responsible for breathing. These conditions, known as locked-in syndrome, leave individuals with intact cognition and awareness but unable to express themselves. Researchers are currently exploring ways to intercept and translate brain signals into words for those with paralysis, providing hope for those who are locked in. The first participant in a clinical trial using this technology, Pancho, survived a devastating brainstem stroke 15 years ago and has since persevered, communicating through laborious neck movements. Despite the challenges, Pancho's story is a testament to the human spirit and the potential for innovation to improve the lives of those with paralysis.
Experiment Restores Speech to Paralyzed Man Using Neurotechnology: A paralyzed man, unable to speak for 15 years, regained the ability to communicate effectively through a brain-computer interface that translated his brain waves into digital signals and generated sentences from a small vocabulary.
A clinical trial was conducted two and a half years ago, where electrodes were implanted onto the parts of a man's brain that control speech. This man, named Pancho, had been paralyzed and unable to speak for 15 years. The surgery involved implanting an electrode array over the speech cortex, connecting it to a port, and then translating the analog brain waves into digital signals that a computer could understand. The first time Pancho spoke through this engineered device was an incredible moment. He was able to see his brain activity translated into text on a screen, and he reacted with excitement, giggling as he tried out new words. The computer was trained to recognize a small vocabulary of 50 words and generate all possible sentences from them, allowing for autocorrect and improving communication. Despite the challenges, such as Pancho's giggles interrupting the decoding, the device was a significant step forward in helping those who are paralyzed or unable to speak communicate more effectively. This groundbreaking experiment demonstrated the potential of neurotechnology to restore speech and improve the lives of those with communication disorders.
Brain-machine interfaces revolutionizing communication and understanding of the human brain: Neuroscientists decode brain activity patterns to generate words and sentences, revolutionizing communication for individuals with disabilities through AI and speech technologies.
The advancements in brain-machine interfaces, such as the work done by neuroscientists like the person being discussed, are revolutionizing the way we communicate and understand the human brain. This technology, which decodes brain activity patterns to generate words and sentences, has the potential to unlock new abilities for individuals with disabilities. The combination of AI and speech technologies is making this possible, even when the decoding is not 100% accurate. This breakthrough is particularly significant for neuroscientists, as it's not often that research in this field leads to clinical applications within one's lifetime. Companies like NeuralLink are also pushing the boundaries of brain-machine interfaces, with goals of enhancing communication and memory capabilities. While the potential for superhuman abilities is intriguing, the ethical and practical considerations surrounding neural circuitry manipulation are complex. The field is at an exciting juncture, with both research and commercialization advancing together. The question of when and if we should pursue superhuman abilities through brain-machine interfaces is a topic for ongoing debate.
Exploring the Future of Human Augmentation: Neurotechnologies are advancing communication and cognitive abilities, but ethical questions arise around invasive procedures and access. Societal implications and nonverbal communication are crucial considerations.
We are on the brink of a new era of cognitive and physical augmentation, building on the long history of human attempts to enhance ourselves. Neurotechnologies, such as brain-machine interfaces, are making strides in enhancing communication and cognitive abilities, like decoding speech from brain signals and helping those who are locked-in to communicate through facial expressions. However, these advancements raise ethical questions, particularly around invasive procedures and access to the technology. While we've already surpassed the boundaries of physical and cognitive augmentation, the rate-limiting step is the technology itself. As we move forward, it's crucial to consider the societal implications and who will have access to these advancements. In the realm of communication, there's a growing need to broaden our definition beyond just verbal communication and consider the importance of nonverbal cues in human interaction.
Effective communication involves both visual and auditory information: Advancements in technology like speech neuro prosthetics and avatars enhance communication for individuals with disabilities by mimicking facial expressions and speech movements, improving understanding and engagement.
Facial expressions and seeing a person's mouth move while they speak play crucial roles in effective communication. The combination of visual and auditory information enhances understanding and makes the experience more natural and memorable. This concept is particularly relevant as we move towards more digital and virtual social interactions. For individuals with disabilities, such as those who are paralyzed, advancements in technology like speech neuro prosthetics and avatars can significantly improve their ability to communicate. These avatars can decode and mimic a person's facial expressions and speech movements, providing a more complete and engaging form of expression. In the future, we may see avatars becoming a common means of communication, even for those without disabilities. Additionally, the use of avatars in social media and other digital platforms can help smooth out the inconsistencies between spoken words and written captions, making communication more accurate and efficient. Furthermore, for individuals with speech conditions like stuttering, advancements in technology and research can help provide relief and better understanding of the underlying causes and potential treatments.
Understanding the complexities of stuttering: Early intervention through speech therapy and focusing on creating smooth word initiation can help manage stuttering. Mental focus, exercise, and minimizing distractions can improve performance in high-precision tasks.
Stuttering is a complex condition related to the coordination of brain functions involved in speech production. While anxiety can exacerbate stuttering, it is not the root cause. The precise coordination between various areas of the vocal tract is necessary for normal speech, and a breakdown in this coordination leads to stuttering. Early intervention through speech therapy can be beneficial, focusing on creating conditions for smooth word initiation and working through anxiety. Additionally, the auditory feedback we receive while speaking plays a role in stuttering, and altering this feedback can impact the severity of stuttering. For optimal performance in high-precision tasks like neurosurgery or complex problem-solving, individuals often engage in practices like exercise and disconnecting from external distractions to enhance mental focus.
A sanctuary for neurosurgeons to save lives: Neurosurgeons find focus and control in the operating room, valuing routine and comparison to personal activities, representing neuroscience's frontier, and maintaining lifelong friendships through shared passions.
The operating room serves as a sanctuary and a source of intense focus for neurosurgeon Andrew, allowing him to disconnect from external distractions and fully engage in the sacred moment of saving lives. He values the routine and control it provides, comparing it to his personal activities like running or listening to music. Neurosurgeons, as explorers of the human brain, represent the frontier of neuroscience, pushing the boundaries of knowledge and application. Andrew's friendship with Eddie, built on a shared love of birds and a deep interest in their field, has lasted for decades, and he remains passionate about the daily challenges and discoveries in his work.
Learn about Dr. Eddie Chang's groundbreaking research and support the Huberman Lab podcast: Discover Dr. Eddie Chang's neuroscience research, listen on podcasts, subscribe to premium channel, and follow Huberman Lab for science updates.
Dr. Eddie Chang's research in the neuroscience of speech and language, epilepsy, and other brain disorders is intellectually important and groundbreaking. Listeners can learn more about his work through the links in the show notes, and they can support the Huberman Lab podcast by subscribing to the YouTube channel, leaving reviews on Spotify and Apple, and considering subscribing to the new premium channel. Additionally, the Huberman Lab Podcast, in partnership with Momentus Supplements, offers a range of supplements that can enhance sleep, focus, and hormone optimization. The proceeds from the premium channel go towards supporting the standard Huberman Lab podcast and various research projects. Finally, subscribing to the neural network newsletter, following Huberman Lab on social media, and signing up for the free newsletter are other ways to stay engaged with the latest science-related information.
