Dr. E.J. Chichilnisky: How the Brain Works, Curing Blindness & How to Navigate a Career Path

Added: Mar 18, 2024

Overview of the Visual System

Dr. Chichilnisky explains that vision begins in the retina, a sheet of neural tissue at the back of the eye that captures light and converts it into electrical signals. The retina consists of three main layers of cells: photoreceptor cells, which detect light and convert it into neural signals; intermediate cells that process and extract features from the visual input; and retinal ganglion cells, which transmit the processed information to the brain.

Function of Retinal Ganglion Cells

Retinal ganglion cells (RGCs) play a crucial role in transmitting visual information to the brain. There are about 20 different types of retinal ganglion cells in humans, each specializing in extracting specific features of the visual world, such as spatial detail, movement, and color. These cells act as "Photoshop filters," sending different representations of the visual scene to the brain for further processing.

Importance of Studying the Retina

While the visual cortex and thalamus are essential for visual perception, studying the retina offers a unique opportunity to understand a specific piece of the nervous system comprehensively. Dr. Chichilnisky finds satisfaction in deeply understanding the retina's function and using that knowledge to engineer devices that can restore vision in individuals who have lost sight.

Comparison with Other Species

The human retina's ability to extract features from the visual world is remarkable, but it is limited compared to some other species. For example, mantis shrimp can see a broader range of colors, while pit vipers can sense heat emissions with their eyes. Each species' visual system is tailored to its biological niche, emphasizing different aspects of the visual environment.

Limitations of Human Vision

Human vision is limited by the number of photoreceptor cells in the retina, which only provide three snapshots of wavelength information. This limitation affects our perception of color, as we have a relatively narrow range of color sensitivity compared to other animals.

Experimental Procedures in the Lab

Dr. Chichilnisky's lab conducts experiments on retinal ganglion cells to study their electrical activity and how they process visual information. He explains that his research often involves using retinas from deceased individuals who have consented to donating their eyes for research purposes. The process involves harvesting the eyes, bringing them back to the lab, and keeping the retina alive to conduct experiments.

When they receive a human retina, they work tirelessly for 48 hours to collect as much data as possible. The retinas are obtained from brain-dead individuals, and it is crucial to extract them within a few minutes of death to preserve their functionality.

Electrophysiological Experiments

In the lab, the retinas are opened up, and small segments of retinal tissue are extracted for electrophysiological experiments. These experiments involve recording and stimulating the electrical signals of RGCs using custom-built equipment with 512 channels. By studying the electrical activity of RGCs, researchers can understand how the retina processes visual information.

Determining Cell Types

To identify cell types, researchers use random visual stimuli, such as flickering checkerboard patterns, to observe how RGCs respond to changes in light intensity, color, motion, and other visual features. By analyzing the electrical activity of RGCs in response to these stimuli, researchers can categorize the cells based on their preferred visual inputs.

Challenges in Studying Cell Types

While researchers have a basic understanding of the seven RGC types that make up 70% of the neurons sending visual information from the eye to the brain, there are 15 other cell types in the retina that remain a mystery. Dr. Chichilnisky mentions ongoing efforts to uncover the roles of these elusive cell types and how they contribute to visual perception. Understanding the full spectrum of cell types in the retina is crucial for developing treatments for vision restoration.

Future Directions in Research

Dr. Chichilnisky highlights the need for studying how RGCs respond to more naturalistic visual stimuli to gain a comprehensive understanding of their functions. By investigating how different cell types process complex visual information, researchers can unravel the mysteries of visual perception and potentially develop innovative approaches for restoring vision in individuals with visual impairments.

Restoring Vision

One of the major sources of blindness is the loss of photoreceptor cells that capture light, leading to conditions like macular degeneration and retinitis pigmentosa. Dr. Chichilnisky proposes bypassing these damaged cells by using an electronic implant that connects directly to the retinal ganglion cells. This implant would capture and process visual information before stimulating the ganglion cells to send signals to the brain. While current retinal implants have shown some success in restoring vision to blind individuals, they are limited in providing high-quality vision. Dr. Chichilnisky's goal is to develop a more advanced implant that can mimic the natural patterns of activity in the retina, leading to improved vision restoration.

Neuroengineering and Augmentation

He envisions a future where neuroengineering can not only restore vision but also enhance human capabilities. By developing devices that can stimulate different cell types in the retina independently, it may be possible to create new visual sensations and augment vision beyond natural capabilities. This could lead to individuals seeing details in the visual world that are currently invisible to the human eye. Additionally, by understanding how different cell types process visual information, researchers can explore ways to interface with other parts of the brain and potentially enhance various cognitive functions.

Responsibility in Technology Development

While the idea of neural augmentation may seem like science fiction, Dr. Chichilnisky emphasizes the importance of developing these technologies responsibly. He believes that leveraging knowledge of the nervous system to build devices that improve human capabilities is a responsible way to advance technology. However, he acknowledges the ethical considerations and potential risks associated with introducing electronic circuits into the brain.

Specificity in Neural Manipulation

Dr. Chichilnisky emphasizes the importance of specificity in manipulating neural circuits to achieve desired effects. He describes the process of recording, stimulating, and calibrating neural activity to understand how electrodes interact with different cell types in the retina. By developing smart devices that can adapt to neural circuits and speak their language, researchers can achieve precise and targeted neural stimulation.

AI and Machine Learning in Neural Engineering

He discusses the role of AI and machine learning in neural engineering, highlighting their use in capturing and analyzing neural activity patterns. By using AI to record, stimulate, and learn from neural responses, researchers can develop devices that can effectively communicate with neural circuits and deliver meaningful stimulation. AI serves as an engineering tool to enhance the specificity and effectiveness of neural prosthetics.

Neural Prosthetics Beyond the Retina

While Dr. Chichilnisky's expertise lies in retinal neuroscience, he acknowledges the impressive advancements in neural prosthetics for other brain regions, such as the spinal cord. Researchers have successfully developed devices that can read signals from the motor cortex and enable paralyzed individuals to control devices with their thoughts. These advancements demonstrate the potential for neural prosthetics to enhance communication and movement in individuals with neurological conditions.

Plasticity and Brain Adaptation

Dr. Chichilnisky addresses the question of whether the adult brain can adapt to increased sensory input, such as enhanced visual resolution from a retinal prosthesis. He discusses the concept of plasticity and gradual adjustments in sensory input to facilitate brain adaptation. By slowly introducing higher visual resolution, researchers can potentially train the brain to make sense of increased sensory information, leveraging mechanisms like spike timing-dependent plasticity to optimize neural connectivity.

Realistic Approach to Neural Engineering

In contrast to sensationalized portrayals of neural implants in popular media, Dr. Chichilnisky advocates for a grounded and incremental approach to neural engineering. He emphasizes the importance of developing smart devices that can sense and adapt to neural circuits, rather than relying on crude stimulation methods. By understanding the neural code and gradually introducing changes, researchers can enhance the effectiveness and compatibility of neural prosthetics with the brain.

Personal Journey and Background

Dr. Chichilnisky shares his unconventional path to becoming a neuroscientist, starting with a background in mathematics during his undergraduate studies at Princeton. He spent time exploring music, travel, and creative pursuits before transitioning to neuroscience research. He pursued a PhD in neuroscience at Stanford University, where he found his mentor, Brian Wandell, who inspired him to focus on neural science.

The Importance of Knowing Oneself

Dr. Chichilnisky emphasizes the importance of knowing oneself, being oneself, and loving oneself. He believes that self-awareness is crucial for making important life decisions and pursuing one's true calling. Through meditation and yoga, he practices self-reflection and self-acceptance, which guide him in his personal and professional endeavors.

The Role of Intuition in Decision-Making

Dr. Chichilnisky relies on intuition and feelings rather than rational thoughts when making decisions. He describes the feeling of "ease" as a sign that he is on the right path. This intuitive sense of knowing guides him in his research and career choices, leading him to work on groundbreaking projects in neuroscience.