Consciousness has fascinated humanity for millennia for its broad implications on science, philosophy, ethics, and religion. Although, some of humanity's greatest minds have attempted to solve the mysteries of consciousness, still very little is resolved in our understanding of what consciousness is and how it works. Most recently neuroscientists have begun to use the scientific method and modern technologies to answer questions about consciousness.
What is consciousness?
Consciousness has been debated for hundreds of years! Scientists might describe consciousness as a state of awareness or perception. Meanwhile, philosophers may use terms such as 'qualia' and 'phenomenology' to describe the feelings associated with a conscious state (for example, the feeling of pain or the taste of a chocolate cake). It is hard to tell who is right or wrong. However, when studying consciousness in the laboratory it is less helpful to use the philosophic terminology to describe consciousness.
Materialism versus Dualism
Materialist and dualist have been debating what the true nature of consciousness is for at least 400 years.
Materialists say consciousness is a physical phenomenon and most likely the result of brain activity. For example, Christof Koch argues consciousness is caused by the pattern of activity across billions of brain cells.
Dualists say consciousness is a nonphysical phenomenon and may be the results of an unknown, nonphysical substance. For example, Rene Descartes argued that consciousness is entirely separate from the body and can exists without the brain. Hence, Descartes most famous declaration: "I think, therefore I am."
Where is consciousness in the brain?
Even if we agree that the materialists are correct (consciousness is in the brain), there are still many questions left unanswered. For example, what part of the brain 'makes' consciousness? In other words, where is consciousness in the brain? There are two broad hypotheses:
1.) Consciousness is generated by one place in the brain.
2.) Consciousness is generated by many places in the brain.
Most evidence points to hypothesis (2), consciousness is made by many places in the brain working together. Some evidence for this comes from patients who damage a part of their brain and loss a piece but not all of their consciousness (for example, in hemispatial neglect patients cannot see from part of their visual field), but the other senses are intact. This shows that different brain regions are involved in making consciousness.
How do neuroscientists study consciousness?
Neuroscientists use two main tools to study consciousness:
(1) Neuroimaging (2) Behavioral Tests
Neuroimaging are safe tools to allow scientists to see what is happening inside an awake or sleeping person's brain. Two main techniques are described below:
Functional magnetic resonance imaging (fMRI) – using blood flow in the brain to predict areas of the brain that are more or less active. FMRI became available in the late 20th century and revolutionized how neuroscientists study cognition (for example, memory, language, thinking, and consciousness). fMRI has excellent spatial resolution, but poor temporal resolution.
Electroencephalography (EEG) – measures the electrical activity created by brain cells (neurons) when they send signals. EEG was discovered in the early 20th century and continues to be a productive tool to study the brain, cognition, and to help treat people with brain diseases (for example, epilepsy). EEG has poor spatial resolution, but excellent temporal resolution.
The main goal of behavioral tests is to compare consciousness versus unconsciousness states. Popular behavioral tests to study consciousness include: change blindness, signal at threshold, visual masking, and binocular rivalry. While people are conscious of all their primary senses (sight, smell, sound, taste, and touch), vision is most studied because it is the easiest sense to tests in a scientific setting and vision is the most well known system in the brain.
Fellow Sharif Kronemer
As an undergraduate, Sharif was nationally ranked in the 800-meter and 8000-meter runs. He is fascinated by consciousness, and explains how we can investigate the human thought process using magnetics and electrodes.