Brain. https://classesv2.yale.edu/

Brain

https://classesv2.yale.edu/

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Evaluation • Midterm (30%) • Final (35%) • Weekly reading responses (15%) • Book review (20%) • Experimental participation

Other stuff • Make contact • How to do well

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This is an odd and unnatural view Maybe you don’t believe it Maybe you believe in dualism

Dualism Descartes (1596-1650) Animals as reflex machines, robots We also have material bodies But our minds are immaterial and nonphyscial

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Dualism Argument 1: The creativity and spontaneity of human action

Dualism Argument 2: “I think Therefore I am.”

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Dualism “

Dualism seems right 1. Language “my arm”, “my heart”, “my body”, “my brain”

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Dualism seems right 2. Personal identity Same person after radical bodily changes

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Dualism seems right 2. Personal identity -- Many people, one body Synopsis: Slapstick, fantastical farce about an eccentric millionairess whose soul inhabits her male lawyer’s body

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Dualism seems right 3. The survival of the self after the destruction of the body

Current view: Dualism is wrong Mind = Brain 1. Problems with dualism 2. We know have a better understanding of what physical things can do (computers & robots) 3. Strong evidence for the role of the brain

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How does the brain work?

Neurons • • • •

About 1,000,000,000,000 Sensory neurons, motor neurons, interneurons All-or-nothing Intensity: expressed through number of neurons firing & frequency of firing

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Neurons • Communication over synapses; axons release neurotransmitters -- excitatory -- inhibitory • Drugs: agonists vs. antagonists -- curare -- alcohol -- amphetamines -- Prozac -- L-DOPA

Is the brain wired up like a personal computer? NO -- because it is: -- highly resistant to damage -- extremely fast … Unlike most human-designed computers, the brain works through massively parallel processing

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What do different parts of the brain do? • You don’t need your brain for everything … -- sucking in newborns -- limb flexion in withdrawal from pain -- erection of the penis -- vomiting

Some subcortical structures Medualla:certain reflexes, heartbeat, breathing Cerebeullum: complicated skilled motor movements Hypothalamus: hunger, thirst, sleep

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Less than 1/4 of the human cortex contains projection areas - the rest is involved with language, reasoning, moral thought, etc.

Some very bad things that could happen to you and your brain • Apraxia • Agnosia -- visual agnosia -- prosopagnosia

• Sensory neglect • Aphasia • Acquired psychopathy

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How many minds do you

have?

Brain has 2 Hemispheres • Left & Right sides are separate • Corpus Callosum : major pathway between hemispheres • Some functions are ‘lateralized’ – language on left – math, music on right

• Lateralization is never 100%

Right Hemisphere

Corpus Callosum

Left Hemisphere

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Sensory Information sent to opposite hemisphere Left visual Right visual field field

• Principle is Contralateral Organization • Sensory data crosses over in pathways leading to the cortex • Visual Crossover

Optic nerves

– left visual field to right hemisphere – right field to left

• Other senses similar Left Visual Corpus Right Visual Cortex Callosum Cortex

Contralateral Motor Control • Movements controlled by motor area • Right hemisphere controls left side of body • Left hemisphere controls right side • Motor nerves cross sides in spinal cord

Motor Cortex

Somatosensory Cortex

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Corpus Callosum • Major ( but not only) Medial surface of right hemisphere pathway between sides • Connects comparable structures on each side • Permits data received on one side to be processed in both hemispheres • Aids motor coordination Corpus Callosum of left and right side

A bit of humility, Part I • Mind as information processor, as computer • Recognition, language, motor control, logic, etc. • But there still remains The Hard Problem of consciousness • Subjective experience, “what it’s like”, qualia

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“How it is that anything so remarkable as a state of consciousness comes about as a result of irritating nervous tissue, is just as unaccountable as the appearance of the Djin, when Aladdin rubbed his lamp.” -- Thomas Huxley

A bit of humility, Part II • Mechanistic conception of mental life • But what about humanist values? -- free will and responsibility -- intrinsic value -- spiritual value? • Can they be reconciled?

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