Daniel Wolpert: The real reason for brains | Summary and Q&A

TL;DR

In this TED talk, a neuroscientist discusses the importance of movement in understanding the brain and how the brain controls movement.

Key Insights

• 🧠 Movement is the primary function of the brain, as it allows us to affect the world around us. Sensory, memory, and cognitive processes are all important, but they exist only to drive or suppress future movements.
• 🕹️ Understanding how the brain controls movement is a difficult problem. While we have made progress in tasks such as chess, dexterous manipulation is still a major challenge. Robots cannot match the agility and fine motor skills of humans.
• 🔍 Bayesian decision theory provides a framework for how the brain deals with uncertainty. The brain combines sensory input with prior knowledge to generate beliefs about the world. The brain also makes predictions and cancels out the sensory consequences of its own actions.
• 💭 The brain's ability to cancel sensory consequences fundamentally changes our perceptions. For example, when we tickle ourselves, our brains predict and subtract the sensation, making it feel less intense. This cancellation of sensory consequences also occurs when we hit someone, leading to inconsistent reports of force.
• ♀️ The brain plans movements to minimize the negative consequences of noise and variability. By choosing movement paths that result in smaller variability, the brain can optimize movement control. This understanding of movement control can have implications for disease and rehabilitation.
• 🧩 Animals' seemingly simple tasks involve complex processes in their brains. Even tasks as simple as cup stacking can have intricate neural processes. The brain's control over movement is far from simple and involves various neural mechanisms and circuits.
• 💡 Studying sensory processes or memory without considering their impact on movement is a mistake. We need to understand how the brain uses these processes to drive or suppress future movement behaviors. Vision, for example, is used differently when considering its role in guiding movement.
• ⭐️ The brain's role in movement control is not just an intellectual challenge, but it also has relevance for robotics, disease treatment, and rehabilitation. Understanding how the brain controls movement can inform the development of robotic technologies and improve our understanding and treatment of movement-related diseases.

Transcript

I'm a neuroscientist. And in neuroscience, we have to deal with many difficult questions about the brain. But I want to start with the easiest question and the question you really should have all asked yourselves at some point in your life, because it's a fundamental question if we want to understand brain function. And that is, why do we and other... Read More

Questions & Answers

Q: What is the fundamental reason why humans and animals have brains?

The fundamental reason why humans and animals have brains is to produce adaptable and complex movements. This is the only reason to have a brain, as movement is the primary way we can affect the world around us. Sensory, memory, and cognitive processes are all important, but only in relation to driving or suppressing future movements.

Q: What is the clinching evidence that proves the importance of movement in the evolution of the brain?

The clinching evidence is the animal called the humble sea squirt. This rudimentary animal has a nervous system and swims around in its juvenile life. However, once it implants itself on a rock and no longer needs to move, it digests its own brain and nervous system for food. This demonstrates that a brain is only necessary when movement is required.

Q: How well are researchers doing in understanding how the brain controls movement?

Researchers are doing poorly in understanding how the brain controls movement. It is considered a very difficult problem to solve. The comparison of building machines that can play chess, where success has been achieved, to building machines that can dexterously manipulate objects like humans, where success is lacking, highlights the challenges in understanding and replicating human movement.

Q: How does the brain deal with the noise and variability associated with sensory feedback and movement?

The brain deals with the noise and variability by utilizing Bayesian decision theory. It makes inferences, predictions, and generates actions based on the combination of sensory input and prior knowledge. The brain's neural simulator predicts the sensory consequences of actions and cancels out those predictions to reduce the negative consequences of noise and variability.

Q: What does it mean for the brain to make predictions of sensory feedback and how does it affect perceptions?

The brain makes predictions of sensory feedback by simulating the physics of the body and senses. It anticipates the sensory consequences of actions and subtracts them from the actual sensory input. By doing so, the brain distinguishes between external events and internal events, fundamentally changing perceptions. This can be seen in studies on tickling and hitting, where self-generated sensations feel different from externally-generated sensations.

Q: How does the brain optimize movements to minimize the negative consequences of noise and variability?

The brain optimizes movements by planning them in a way that minimizes the negative consequences of noise and variability. It avoids big forces and plans movements with less variability. The goal is to minimize the effects of noise and ensure more accurate and consistent movements. This understanding can contribute to disease management, rehabilitation, and advancements in robotic technology.

Summary & Key Takeaways

• The main purpose of having a brain is to produce adaptable and complex movements, as movement is the primary way we interact with and affect the world.

• Sensory, memory, and cognitive processes are important, but their main purpose is to drive or suppress future movements.

• The brain makes predictions and cancels out sensory feedback to reduce the negative consequences of noise and variability in movement.