Phineas Gage, a 25-year-old railroad foreman in 1848, is one of the most renowned cases in neuroscience. He suffered a severe brain injury when an explosion drove a tamping iron through his face and skull, damaging his frontal lobe. Miraculously, Gage survived the accident, remaining conscious and able to walk and speak immediately after. However, in the following months, he underwent a profound personality transformation. Previously known as a well-mannered man, he began to exhibit strange and inappropriate behavior. This shift in personality is attributed to a loss of impulse control, a key function managed by the frontal lobe.

Phineas Gage

The medical condition of brain death, where an individual's brain function has ceased but their body is sustained by medical equipment, creates intricate ethical problems. These dilemmas involve complex decisions about appropriate medical responses, such as determining who has the authority to remove a feeding tube or discontinue life support. Resolving these issues requires weighing conflicting factors like patient wishes, family desires, state laws, hospital policies, and the potential impact of medical care costs.

Ethical Dilemmas Concerning Brain Death and Life Support

A patient suffers an injury to a specific, localized area of the brain. Following the injury, the patient's vision remains sharp, and they can identify everyday objects without difficulty. However, they are completely unable to recognize the faces of their closest relatives or even their own face in a mirror. Based *only* on this evidence, what is the most logical inference about the function of the damaged brain area?

Strokes, which result from an interruption of blood flow to a part of the brain, cause a localized loss of brain function. By studying the specific behavioral changes or deficits that follow a localized stroke, researchers are able to link those functional impairments directly to the damaged region, thereby identifying the normal role of that specific brain area.

Using Strokes to Study Brain Area Functions

The extensive study of individuals with brain damage has been a primary method for gathering information about the functional roles of different areas of the brain.

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The expanded, front section of the central nervous system located within the skull. It is an incredibly intricate organ made up of billions of interconnected neurons and glial cells. The brain is a bilateral structure, meaning it has two sides, and can be divided into distinct lobes. Each lobe is linked to specific functions, but all parts of the brain work together to underpin our thoughts and behaviors.

Brain

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

There exists a progression of processing that starts at lower-level areas of the brain and moves to higher-level areas. These lower-level areas respond to simple stimuli and send their feedback to areas in charge of more complex tasks in pursuit of eventually forming a representation.

Hierarchical Processing

Different cognitive processes take different paths through the brain. Some notable pathways are:
- the what pathway
- the where pathway
- perception pathway
- action pathway

Pathways in the brain

Specific areas of the brain serve different specific functions

Localization of function

The interacting brain regions that are engaged when we are not working on a task or focused on the external world. The same regions are active when we think about people (so our default thoughts are often about people).

Default mode network

A group of subcortical nuclei, that is well connected with the cerebral cortex, thalamus, and brainstem. It is associated with control of voluntary motor movements, procedural learning, habit learning, eye movements, cognition, and emotion. Stores habits even when the rest of the brain is "asleep". (It is the red region in the image; blue = related structures).

Basil Ganglia (basil nuclei)

The brain is divided into three primary sections based on their relative size and position: the forebrain, the midbrain, and the hindbrain. The forebrain is the largest portion of the brain, while the midbrain is a smaller section located centrally. The hindbrain is situated in the lower back part of the brain.

Three Main Parts of the Brain

* Phineas Gage 
* Henry Molaison (H.M.)
* John Nash
* Clive Wearing
* James Wannerton

Influential Case Studies in Brain Function and Behavior

The meninges are the membrane layers that protect the surrounds the brain. They are found beneath the skull.

Meninges

A central task for psychologists is to understand the relationship between the body's internal biological processes and their external psychological expressions. For instance, a key challenge is explaining how the complex activity of millions of neurons in the brain translates into a subjective experience like a thought. This is analogous to understanding how a device's internal circuits and microchips produce the functions we observe on its user interface.

The Mind-Body Connection as a Focus of Psychology

Although distinct lobes and areas of the brain are associated with specific functions, they do not operate in isolation. All brain regions interact and communicate with one another, and this integrated activity forms the basis for our thoughts and behaviors.

Interaction of Brain Areas

Studying Brain Damage to Understand Brain Function

Brain imaging techniques provide a non-invasive way to study the brain's functions, complementing insights gained from analyzing brain injuries. These methods can be applied to healthy individuals to obtain information about how different parts of the brain operate, often relying on radiation, magnetic fields, or electrical activity.

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