The Tale of the Dueling Neurosurgeons | Sam Kean

Summary of: The Tale of the Dueling Neurosurgeons: The History of the Human Brain as Revealed by True Stories of Trauma, Madness, and Recovery
By: Sam Kean

Introduction

Embark on a fascinating journey through the human brain as revealed by true stories of trauma, madness, and recovery in ‘The Tale of the Dueling Neurosurgeons’ by Sam Kean. In this summary, you will explore the history of neuroscience and the pioneers who studied individuals with brain damage to uncover the inner workings of the brain. Discover how the lower, middle, and upper regions of the brain control crucial body functions, and learn about the various types of memory and brain disorders. Gain insight of how human consciousness and personality are derived from several brain structures and functions, as well as how researchers unravel the mysteries of the mind.

Decades Ago, Neuroscience Used to Mean Drilling Holes in People’s Heads

In the past, neuroscience was studied mainly through autopsies of those with brain damage, which led to breakthrough discoveries like the first autopsy of King Henri II of France. Scientists discovered that post-mortems provided valuable insights into the inner workings of the brain and helped establish the credibility of autopsies as a means of scientific research. Individuals with brain disorders often perceive the world oddly or behave in unusual ways, which helped researchers ascertain what activities specific brain regions were responsible for.

A Closer Look at the Human Brain

The human brain is a highly organized organ responsible for various functions. The lower brain controls basic body functions while the cerebellum coordinates movement. Information relayed around the brain and body is done by the middle brain, which contains a set of brain structures known as the limbic system responsible for memory and emotion. More complex functions like planning and decision-making are carried out in the cortex, which is subdivided into four main regions, each specializing in different tasks. The occipital lobes located at the back of the brain process vision, and damage to them can result in hallucinations like in King Henri II’s case. Despite appearing, as gray lump to the untrained eye, the human brain is highly organized, down to a microscopic level.

The Power of Neurons

Our brain is made up of cells called neurons, which collect and transmit information through electrical signals. The neurons consist of a cell body, an axon, and dendrites. The dendrites gather information directly from the sensory organs or other neurons and if the intensity of the signal passes a certain threshold, the cell body triggers an electrical signal in response. The signal is passed along the neuron chain until it reaches the brain, where it is processed and orders are sent out to the body. Glial cells, which are less complex than neurons, feed and stabilize the massive neuron network and are equally important. The absence of glial cells has disastrous consequences, as seen in Charles Guiteau who suffered from a syphilis-induced brain infection that killed off his glial cells one by one. The neurons and blood vessels in his brain couldn’t get enough nourishment without them, which drove him to insanity.

The Miraculous Neuronal Pathways

Neurons communicate through synapses and neurotransmitters, leading to sensory experiences. The elasticity of these pathways enables compensatory growth when a sense is lost. Blind individuals can use echolocation to create a visual experience, revealing the interconnectedness of various brain regions.

The Specialization of Neuron Clusters

The brain is made up of specialized neuron clusters that enable humans to identify objects and monitor body parts. These clusters have specific regions that trigger different responses based on the information they process. For instance, the fusiform face area (FFA) helps discern between faces, while the “where-stream” processes the location and movement of objects. Furthermore, the “what-stream” helps identify objects by responding to specific lines, angles, and locations in the visual field. Additionally, the somatosensory cortex monitors body parts and initiates their movements, representing each limb in its gray matter. Therefore, amputees experience sensations in missing limbs because it is still connected to the somatosensory cortex. Brain disorders like face blindness can be a result of issues in the FFA. The brain’s ability to form these specialized clusters allows for complex hand-eye coordination and the identification of various objects in the surroundings.

Emotions, Memories, and Good Decisions

Our emotions and memories are processed in the limbic system, while good decisions are formed by the frontal lobes. The case studies of Elliot and Phineas Gage illustrate the significance of the connection between these regions.

Have you ever found yourself crying before you realized why? This happens because sometimes the brain generates feelings before it processes rational thoughts. Feelings are helpful as they allow you to label incoming information immediately. Emotions and memories are formed in the limbic system, comprising parts like the thalamus, hippocampus and amygdala.

The thalamus recognizes and labels sights and sounds. The hippocampus helps create both short-term and long-term memories. The amygdala plays a role in attention, fear, aggression, hunger, and sex drive. The frontal lobes help plan actions and make choices. To make good decisions, we need the limbic system and rational frontal lobes working together.

The case of Elliot, a man who lost his ability to make simple choices after a tumor severed his frontal lobes and limbic system, further highlights the significance of connections between these regions. Elliot’s personality, emotions, and memory stayed intact, but he struggled with even basic decisions. Similarly, when a pipe shot through Phineas Gage’s brain, blowing out parts of his thalamus and prefrontal lobes, he changed from an honest man into a reckless gambler. These two real-life cases show us how emotions, memories, and good decision-making are all connected in a balance.

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