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This story is part of a series on current developments in Regenerative Medicine. This piece discusses developments in neuroscience.
In 1999, I defined regenerative medicine as the collection of interventions that restore normal function to tissues and organs that have been damaged by disease, injured by trauma, or worn down by time. I include a full spectrum of chemical, gene, and protein-based drugs, cell-based therapies, and biomechanical interventions that achieve this goal.
Recent research into brain stimulation associated with speech may show how we plan what we say before we say it. The study by Kabakoff and colleagues in Brain communications analyzes the areas of the brain that influence speech patterns and errors when simulated electronically. This knowledge could lead to more advanced speech therapies in the very near future.
The workings of the human mind have always been the subject of intrigue and fascination, and one of its most fascinating functions is speech. Through speech, we convey our innermost thoughts, feelings and concepts to others and it serves as a means of connection between us and the world around us. However, the relationship between mind and speech is complex, and continues to be the subject of study and exploration.
For years, scientists have analyzed the complexity of speech production. While it is widely accepted that the cerebral cortex is a critical component in speech, particularly in the initiation of the physical act of speech, the planning phase of speech has remained relatively unexplored. However, the new data may lead to a better understanding of how we design what we say.
A recent NYU Grossman School of Medicine study analyzed hundreds of brain mapping recordings from 16 patients being prepared for epilepsy surgery.
Before the operation, the surgeons conducted a safety procedure to ensure that no vital areas of the brain were removed during the operation that could affect the ability to speak. This procedure involved electrical stimulation of specific parts of the brain while patients performed simple speech tasks.
During these procedures, the researchers observed the effect of stimulation on the speech production of a specific brain region, particularly the time it took for the stimulation to affect speech.
For example, the surgeon may ask the person to recite the Pledge of Allegiance, during which different areas of the brain will be stimulated and speech will be affected, either by confusion or total loss of speech.
Stimulation would lead to either a motor arrest, which includes a speech interruption due to damage to the vocal tract, or a speech interruption, which the researchers define as a speech interruption that cannot be explained by a motor interruption.
FIGURE 1: Cortical locations and latency distributions for all motor stop and speech hits, … [+]
Stimulation of the sensorimotor cortex caused the most motor interruptions (87.5%), while many different brain regions led to speech interruptions.
Different areas of the brain also responded differently to the stimulation. While some regions responded quickly, others took almost twice as long to affect the speech production process.
FIGURE 2: Map of the density of speech stop spikes across the cortex in four time bins of adjusted … [+]
Two neighboring cortical regions, the ventral sensorimotor cortex and the inferior frontal gyrus, have been found to exhibit longer latencies, between 0.5 and 1 second, during speech planning. The ventral sensorimotor cortex is involved in the muscle movements necessary for speech production. In contrast, the inferior frontal gyrus involves various aspects of language processing, including grammar and syntax. Together, these two brain regions work in tandem to facilitate the complex process of speech production.
In contrast, shorter latencies of less than 0.5 s were observed in other parts of the motor cortex and in other gyri, indicating that these regions play a more critical role in the natural mechanics of speech.
FIGURE 3: Smooth distribution of fitted latencies including speech stop hits plotted with … [+]
These results are exciting and may have profound implications in the near future. Brain mapping efforts work to map properties and properties of brain function spatially.
Brain mapping is often used to diagnose nerve blocks related to speech, vision, and movement. A stronger understanding of the human brain could improve techniques for diagnosing and treating neurological disorders and pave the way for more advanced neuroprosthetics to help people with speech, vision and movement problems.
Understanding the neural mechanisms underlying speech production and language processing enables future scientists and engineers to develop more powerful speech recognition and natural language processing technologies with artificial intelligence.
The future of neurological understanding and the cascade of implications this understanding will entail, both in neuroscience and neurotechnology, is bright. We are living on the cusp of a new renaissance in regenerative medicine, bioelectronics and medical devices — future advances that could help the lives of thousands if not millions.
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