Essentials: The Neuroscience of Speech, Language & Music | Dr. Erich Jarvis

Jarvis draws on his personal experience as a former professional dancer who transitioned to science. He noticed that during periods when he danced less (like during the pandemic), he felt a cognitive difference. He argues against the traditional scientific separation between movement and cognition, and between perception and production. Because the speech pathway is adjacent to the movement pathways, engaging in whole-body movement like dancing helps keep the brain fresh and cognitively intact. He extends this to recommend not just dancing but also walking, running, and practicing speech, oratory, or singing—all of which control brain circuits that move facial musculature and keep cognitive circuits in tune.

Jarvis explains that his lab accidentally discovered stuttering in songbirds when they damaged the basal ganglia in the speech-like pathway. The birds stuttered as the brain region recovered and new neurons entered the circuit with improper activity. Unlike humans, the birds recovered after several months because bird brains undergo neurogenesis differently. In humans, damage or disruption to the basal ganglia at a young age causes stuttering, and even those born with stuttering often have basal ganglia disruption. Jarvis states that behavioral therapy tools for overcoming stuttering all have something to do with sensory-motor integration—controlling what you hear with what you output in a thoughtful, controlled way.

Jarvis argues there is no good evidence for a separate language module. Instead, he proposes that the speech production pathway—which controls the larynx and jaw muscles—has built within it all the complex algorithms for spoken language. Similarly, the auditory pathway has built within it all the complex algorithms for understanding speech. The speech production pathway is specialized in humans, parrots, and songbirds, while the auditory perception pathway is more ubiquitous across the animal kingdom. This explains why dogs can understand several hundred human speech words and great apes can learn several thousand, but neither can produce speech. The distinction is not between language and speech, but between learned vocal production and auditory comprehension.

Jarvis explains that the brain regions controlling spoken language are directly adjacent to those controlling hand gesturing. This hand parallel pathway also has complex algorithms that can be utilized for communication. Some species are more advanced in gestural circuits than in vocal circuits. Humans are the most advanced at spoken language, but the gap between humans and other species is smaller for gestural language. This explains why Koko the gorilla could learn sign language and understand spoken words but could not produce speech with her voice—she had the motor pathways for learned gesturing but lacked the extra brain pathway for learned vocalization. Jarvis frames this as 'gesturing with the voice' versus 'gesturing with the hands,' suggesting spoken language is essentially a specialized form of motor gesturing.