A report on Consciousness

Representation of consciousness from the seventeenth century by Robert Fludd, an English Paracelsian physician
John Locke, British Enlightenment philosopher from the 17th century
Illustration of dualism by René Descartes. Inputs are passed by the sensory organs to the pineal gland and from there to the immaterial spirit.
Thomas Nagel argues that while a human might be able to imagine what it is like to be a bat by taking "the bat's point of view", it would still be impossible "to know what it is like for a bat to be a bat." (Townsend's big-eared bat pictured).
John Searle in December 2005
The Necker cube, an ambiguous image
A Buddhist monk meditating
Neon color spreading effect. The apparent bluish tinge of the white areas inside the circle is an illusion.
Square version of the neon spread illusion

Sentience or awareness of internal and external existence.

- Consciousness
Representation of consciousness from the seventeenth century by Robert Fludd, an English Paracelsian physician

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Drawing by Santiago Ramón y Cajal (1899) of neurons in the pigeon cerebellum

Neuroscience

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Scientific study of the nervous system and its functions.

Scientific study of the nervous system and its functions.

Drawing by Santiago Ramón y Cajal (1899) of neurons in the pigeon cerebellum
Illustration from Gray's Anatomy (1918) of a lateral view of the human brain, featuring the hippocampus among other neuroanatomical features
The Golgi stain first allowed for the visualization of individual neurons.
Human nervous system
Photograph of a stained neuron in a chicken embryo
Proposed organization of motor-semantic neural circuits for action language comprehension. Adapted from Shebani et al. (2013)
Parasagittal MRI of the head of a patient with benign familial macrocephaly

The understanding of the biological basis of learning, memory, behavior, perception, and consciousness has been described by Eric Kandel as the "epic challenge" of the biological sciences.

Christof Koch, 2008

Christof Koch

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Christof Koch, 2008

Christof Koch (born November 13, 1956) is a German-American neurophysiologist and computational neuroscientist best known for his work on the neural basis of consciousness.

Stream of consciousness (psychology)

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The stream of consciousness is a metaphor describing how thoughts seem to flow through the conscious mind.

Alcohol is a widely used and abused psychoactive drug. The global alcoholic drinks market was expected to exceed $1 trillion in 2013. Beer is the third-most popular drink overall, after water and tea.

Psychoactive drug

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Psychoactive_Drugs_Legend.jpg: 1. caffeine

Psychoactive_Drugs_Legend.jpg: 1. caffeine

Alcohol is a widely used and abused psychoactive drug. The global alcoholic drinks market was expected to exceed $1 trillion in 2013. Beer is the third-most popular drink overall, after water and tea.
Zoloft (sertraline) is an SSRI antidepressant.
Timothy Leary was a leading proponent of spiritual hallucinogen use.
Illustration of the major elements of neurotransmission. Depending on its method of action, a psychoactive substance may block the receptors on the post-synaptic neuron (dendrite), or block reuptake or affect neurotransmitter synthesis in the pre-synaptic neuron (axon).
Comparison of the perceived harm for various psychoactive drugs from a poll among medical psychiatrists specialized in addiction treatment (David Nutt et al. 2007).
Historical image of legal heroin bottle

These substances may be used medically, recreationally, or spiritually; to purposefully improve performance or alter one's consciousness; as entheogens for ritual, spiritual, or shamanic purposes, or for research.

Tissue slice from the brain of an adult macaque monkey (Macaca mulatta). The cerebral cortex is the outer layer depicted in dark violet. Source: BrainMaps.org

Cerebral cortex

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Outer layer of neural tissue of the cerebrum of the brain in humans and other mammals.

Outer layer of neural tissue of the cerebrum of the brain in humans and other mammals.

Tissue slice from the brain of an adult macaque monkey (Macaca mulatta). The cerebral cortex is the outer layer depicted in dark violet. Source: BrainMaps.org
Lateral view of cerebrum showing several cortices
Diagram of layers pattern. Cells grouped on left, axonal layers on right.
Three drawings of cortical lamination by Santiago Ramon y Cajal, each showing a vertical cross-section, with the surface of the cortex at the top. Left: Nissl-stained visual cortex of a human adult. Middle: Nissl-stained motor cortex of a human adult. Right: Golgi-stained cortex of a 1 1⁄2 month-old infant. The Nissl stain shows the cell bodies of neurons; the Golgi stain shows the dendrites and axons of a random subset of neurons.
Micrograph showing the visual cortex (predominantly pink). Subcortical white matter (predominantly blue) is seen at the bottom of the image. HE-LFB stain.
Arterial supply showing the regions supplied by the posterior, middle, and anterior cerebral arteries.
Cortical blood supply
Neurogenesis is shown in red and lamination is shown in blue. Adapted from (Sur et al. 2001)
Human cortical development between 26 and 39 week gestational age
Depicted in blue, Emx2 is highly expressed at the caudomedial pole and dissipates outward. Pax6 expression is represented in purple and is highly expressed at the rostral lateral pole. (Adapted from Sanes, D., Reh, T., & Harris, W. (2012). Development of the Nervous System (3rd ed.). Burlington: Elsevier Science)
Some functional areas of cortex
Motor and sensory regions of the cerebral cortex
Motor and sensory regions of the cerebral cortex
Cortical areas involved in speech processing.
Hemodynamic changes observed on gyrencephalic brain cortex after an arterial vessel occlusion in IOS. The video has a speed of 50x to better appreciate the spreading depolarization over the brain cortex. Pictures are dynamically subtracted to a reference picture 40 s before. First we see the initial are of change at the exact moment where the middle cerebral artery group (left) is occluded. The area is highlighted with a white line. Later we appreciate the signal produced by Spreading Depolarizations. We see markedly the front of waves.
thumb|Lateral surface of the human cerebral cortex
thumb|Medial surface of the human cerebral cortex
Arterial supply showing the regions supplied by the posterior, middle, and anterior cerebral arteries.
Cortical blood supply

It plays a key role in attention, perception, awareness, thought, memory, language, and consciousness.

Acute confusional state caused by alcohol withdrawal, also known as delirium tremens

Delirium

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Organically caused decline from a previous baseline of mental function that develops over a short period of time, typically hours to days.

Organically caused decline from a previous baseline of mental function that develops over a short period of time, typically hours to days.

Acute confusional state caused by alcohol withdrawal, also known as delirium tremens

While requiring an acute disturbance in consciousness/attention and cognition, delirium is a syndrome encompassing an array of neuropsychiatric symptoms.

A simple classification scheme for ASC. Sleep and dream states are distinguished from waking consciousness since they account for substantially different ways of the ability of memory formation and retrieval. Psychiatric diseases that go along with persistent changes of consciousness, like schizophrenia, are covered with the term "pathological conditions". In contrast, the classification scheme includes intended and induced ASCs as well as general fluctuations of neurotransmission, which are reversible and short-termed. One step further the graph suggests splitting induced ASCs in persistent and reversible states. Translated from German Schmidt & Majic.

Altered state of consciousness

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Any condition which is significantly different from a normal waking state.

Any condition which is significantly different from a normal waking state.

A simple classification scheme for ASC. Sleep and dream states are distinguished from waking consciousness since they account for substantially different ways of the ability of memory formation and retrieval. Psychiatric diseases that go along with persistent changes of consciousness, like schizophrenia, are covered with the term "pathological conditions". In contrast, the classification scheme includes intended and induced ASCs as well as general fluctuations of neurotransmission, which are reversible and short-termed. One step further the graph suggests splitting induced ASCs in persistent and reversible states. Translated from German Schmidt & Majic.

There are many ways that one's consciousness can be altered, such as by using psychoactive drugs, which are defined as chemical substances that pass through the blood brain barrier and disturb brain function, causing changes in awareness, attitude, consciousness, and behavior.

Hameroff in 2008

Stuart Hameroff

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Hameroff in 2008

Stuart Hameroff (born July 16, 1947) is an American anesthesiologist and professor at the University of Arizona known for his studies of consciousness and his controversial contention that consciousness originates from quantum states in neural microtubules.

Analytic philosophy

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Branch and tradition of philosophy using analysis, popular in the Western world and particularly the Anglosphere, which began around the turn of the 20th century in the contemporary era in the United Kingdom, United States, Canada, Australia, New Zealand, and Scandinavia, and continues today.

Branch and tradition of philosophy using analysis, popular in the Western world and particularly the Anglosphere, which began around the turn of the 20th century in the contemporary era in the United Kingdom, United States, Canada, Australia, New Zealand, and Scandinavia, and continues today.

In recent years, a central focus of research in the philosophy of mind has been consciousness.

Subjectivism

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Doctrine that "our own mental activity is the only unquestionable fact of our experience", instead of shared or communal, and that there is no external or objective truth.

Doctrine that "our own mental activity is the only unquestionable fact of our experience", instead of shared or communal, and that there is no external or objective truth.

One can also hold that it is consciousness rather than perception that is reality (idealism).