Neuroscience and magnetic fields: David Dickman at TEDxRiceU 2014

Summary

This presentation explores the remarkable ability of various animals to navigate using the Earth's magnetic field, a sense humans lack. It delves into the brain's regions activated by magnetic fields, particularly in pigeons, and the potential mechanisms behind magnetoreception. The speaker suggests that while the brain evolved to control movement, it also adapts to navigate through technology, extending our natural capabilities.

Takeaways

• 🧠 The speaker is a neuroscientist discussing the fascinating abilities of certain animals to navigate using the Earth's magnetic field, a capability humans lack.
• 🌐 Animals such as migratory birds, sea turtles, and honeybees have evolved to detect the Earth's magnetic field for navigation, a sense referred to as 'magnetoreception'.
• 🕊️ Pigeons, known for their excellent navigation skills, were used in the study to understand how they might detect and process magnetic information.
• 🧲 The Earth acts as a large bar magnet with magnetic field lines exiting the South Pole and entering the North Pole, varying in inclination and intensity across latitudes.
• 🔬 The speaker's team built a specialized laboratory to study magnetoreception, including a magnetic field generator to simulate various magnetic conditions.
• 📊 They discovered that different regions of a pigeon's brain are activated by the magnetic field, suggesting a neural pathway for magnetic reception.
• 🔍 The study used molecular engineering to identify specific brain cells activated by magnetic fields, indicating regional specialization for this sense.
• 🌀 The brain cells respond to the magnetic field's direction and intensity, with some cells preferring specific inclination angles and intensity levels.
• 📈 The speaker describes a three-dimensional cosine function as the best mathematical model to fit the magnetic field responses of the recorded brain cells.
• 🤔 There are three theories on how animals might detect magnetic fields: photopigments in the eye, iron particles in beaks, and the presence of magnetite in the lagena of the inner ear.
• 📱 The speaker concludes by highlighting how human brains have evolved to use technology to overcome sensory limitations, such as detecting magnetic fields through smartphones.

Q & A

What is the main topic of the speaker's presentation?

The main topic of the presentation is the ability of some animals to detect and use the Earth's magnetic field for navigation, a phenomenon known as magnetoreception.

What is the term used to describe the animals' ability to detect the Earth's magnetic field?

The term used to describe this ability is 'magnetoreception'.

Why is the sense of magnetoreception considered mysterious?

It is considered mysterious because we do not fully understand how animals perceive and process the Earth's magnetic field, nor do we know the endpoint goal of their navigation mechanism.

Which animals are mentioned in the script as examples of magnetoreceptive species?

The animals mentioned include migratory birds in Northern Scandinavia, sea turtles, honey bees, and bats in North America.

What is the significance of the Earth's magnetic field for navigation in animals?

The Earth's magnetic field is significant for navigation as it allows animals to determine their special location, heading direction, and navigational goal endpoint.

What is the role of Bayesian inference in the context of this presentation?

Bayesian inference is used as a probabilistic statistics function that takes different cues such as magnetic reception, visual velocity, and the vestibular system to determine an animal's heading direction.

What is the Earth's magnetic field like, and how does it vary across the planet?

The Earth's magnetic field consists of lines that exit at the magnetic South Pole, circle the Earth, and enter at the North Pole. The field lines have different inclination angles and intensities that systematically vary, being highest at the poles and lowest at the equator.

What is the lab setup for studying the Earth's magnetic field in animals?

The lab setup includes a shielded room like an MRI facility, a motion platform, and a cube with field coils to generate a magnetic field in any direction and intensity. Pigeons were chosen as the animal model for these studies.

How do researchers determine which parts of the brain are activated by the magnetic field?

Researchers use molecular engineering with antibodies attached to fluorescent markers to identify cells activated by magnetic field stimulation. This reveals regions in the brain that are specifically activated by the magnetic field.

What are the three theories proposed for the magnetic transduction mechanism in animals?

The three theories are: 1) the presence of photopigments in the eye called cryptochromes, 2) the use of iron particles found in the beaks of pigeons, and 3) the presence of a third receptor type in the vestibular system, called the lagena, which contains iron particles.

What is the significance of the speaker's final point about the human brain and technology?

The speaker suggests that while humans do not naturally possess magnetoreception, through science and technology, we have developed the ability to detect the Earth's magnetic field and use it for navigation, showcasing the brain's capacity to evolve and adapt.