psychology – ms. shirley unit 2 - biological bases of behavior, bio & the neuron

Psychology – Ms. Shirley Unit 2 - Biological Bases of

Behavior, Bio & The Neuron

“The astonishing hypothesis - You, your joys and your sorrows, your sense of identity, and your free will, are no more than the vast assembly of nerve cells and their molecules.”

- Francis Crick, Nobel Prize winning Biologist

This is an odd and unnatural view... at first.Most people don’t believe it. Maybe you don’t believe itMost believe in dualism.

As Rene Descarte did. “Are humans merely physical machines?” He answered no. Animals are machines, he said. But people have a duality.

What we are is not physical, we are immaterial souls that have a physical body.

17th century perpetual motion machines of the French gardens.

Descarte knew what an automated machine (or robot) would be like.

Certainly humans were much better than that.

DualismDescartes Argument #1: The creativity & spontaneity of human action

The use of language for instance. “How are you?” “I’m OK.” (standard

response)

But, one could go into detail, you have the choice, you are not a machine:

“I’m pretty darn awesome, if I do say so myself!”

DualismDescartes Argument #2:

“I think, Therefore I am.”Of what could Descartes be sure of?

★ What if everything I am experiencing is just a dream?

★ Or if it is a trick of some demon? ★ Do I even have a body? ★ Or is that too just an illusion? ★ How do I know I’m not crazy?

1 thing he can not doubt... he is, himself...

thinking.

This was the launching point for philosophy.

DualismDescartes Argument #2:

“I think, Therefore I am.”There is something really different about having a mind. The soul by which I am, what I am, is entirely distinct from my body.

Isn’t it just common sense?

“My arm” - “My heart”“My child” - “My car” - “My leg”

We talk about owning our body as if we are separate from them.

Dualism seems rightArgument #2: Personal identitySame person after radical bodily changesPersonal identity: Many people, 1 bodySynopsis: Fantasy. But believable in fictional movie form. We go along for the ride and believe it, because the dualist perspective seems right.

You can imagine it... because we believe it for ourselves.

Dualism just seems rightArgument #2. Personal identity

Many people, 1 bodySynopsis: Movie “All of Me”... fantastical farce about an eccentric millionaires whose soul inhabits her male lawyer’s body.

Cultural Traditions Back DualismArgument #3: The survival of the self after the destruction of the body “What will happen when you die?” Fate of the soul? (cultures vary, but share the idea of what you are is separable from this physical thing you carry around. The body can be destroyed, the soul lives on.)

Christians: 96% --> heavenJewish: Most said heavenAtheists: “I’m gonna go to heaven.”

Current scientific view: Dualism is wrong!Mind = Brain “The mind is what the brain

does.”Just like computation is the product of a computer.Problems with dualism - science.1. We now have a better

understanding of what physical things can do (computers & robots)

2. Strong evidence for the role of the brain

Mind = Brain “The mind is what the brain does.”

A computer can beat you at chess, but... can a computer read your mind?If so, is that proof that your mind is what the brain does?

YouTube: 60 Minutes - Reading Your Mind

NeuronsAbout 1,000,000,000,000 [1,000 Billion]★ Sensory neurons, ★ Motor neurons, ★ Interneurons (connect Sensory & Motor)

Neurons can regenerate!

All-or-nothingIntensity: expressed through

number of neurons firing & frequency of firing

NeuronsAll-or-nothingIntensity: expressed

through number of neurons firing & frequency of firingAlthough neurons are all or

nothing, there are ways to “code intensity.” Could be the sheer # of neurons or the frequency of firing.

Neurons

Synapse - tiniest little gap. Where the neuron communicates chemically. 1/10,000 of a millimeter wide. When a neuron fires the axon sends chemical shooting through the gap.

Communication over synapses; axons release neurotransmitters

★ excitatory★ inhibitory

Drugs: agonists vs. antagonistsagonist - increases effect of neurotransmitters.antagonists - slow down the amount of neurotransmitters (destroy connections, or block them)

★ curare antagonist - blocks motor neurons - paralyzes you.

★ alcohol inhibitory - it relaxes/shuts down the portion of the brain that tells you not to do things. Result - you are ‘less inhibited.’

★ amphetamines speed/coke - increase the amount of arousal & Norepinephrine- neurotransmitter responsible for awareness & arousal

★ Prozac works on serotonin, depression = neurotransmitter issue, not getting enough serotonin

★ L-DOPA - Parkinson’s Disease is a lack of dopamine & L-Dopa... in part

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

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★ vomiting

What does the brain do? Some subcortical structuresMedulla: certain reflexes, heartbeat, breathingCerebellum:

complicated skilled motor movements (contains 30 billion neurons!)

Hypothalamus: hunger, thirst, to some extent sleepCerebral Cortex:

Where the action is! The outer layer. The crumpled up part. The wrinkles. 2 feet sq. if you took it out and flattened it. 80% of our brain is cortex.

Cerebral Cortex - Mapping or Projection Areas

1. topographical2. size in the brain of the body part is the extent to which they have motor or sensory control.

ex. shoulder is tiny. The mouth is HUGE.

Some subcortical structures

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 brainApraxia - can not coordinate their

movements.Agnosia - disorder that isn’t

blindness, their eyes are intact. They lose the ability to recognize things.

★ visual agnosia - failure to recognize objects

★ prosopagnosia - failure to recognize faces

Sensory neglect - disorder where one could no longer be able to use a side of their body, or even know about anything on that side of you - in a sensory way.Aphasia - Broca - “Tan.” “Tan, tan,

tan, tan!”Acquired psychopathy - Damage to

parts of your brain (frontal lobe) rob you from the ability to tell right from wrong.

How many minds do you have?

YouTube: Right Brain vs. Left Brain - The man with 2 brains

Brain has 2 Hemispheres

Left & Right sides are separateCorpus Callosum: major

pathway between hemispheresSome functions are

‘lateralized’★ language on left★ math, music on right

Lateralization is never 100%

Sensory Information sent to opposite hemisphereContralateral OrganizationSensory data crosses over in pathways leading

to the cortex

Visual Crossover left visual field to right hemisphereright field to left

*Other senses similar

Contralateral Motor ControlMovements controlled by motor area

★ Right hemisphere controls left side of body

★ Left hemisphere controls right side

★ Motor nerves cross sides in spinal cord

Corpus CallosumMajor (but not the only) 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

The Story of HMHenry Gustav Molaison (who became famous as ‘HM‘ in neuroscience textbooks) was born on February 26, 1926. After a bicycle accident at the age of 7 he suffered from debilitating epilepsy and in 1953 he underwent neurosurgery in an attempt to contain seizures.Doctors localised HM’s epilepsy in his medial-temporal lobes and removed a large part of the hippocampus in both hemispheres. At the time they had no idea of how crucial these areas are for the normal functioning of the human brain…

Soon after the operation it became clear that something was wrong. HM suffered from severe anterograde amnesia: he was otherwise normal but no longer able to commit events to memory.

He would not remember the newspaper he had just read or the people he met a few minutes ago, he was stuck in the present.

Before surgery, 1953

Brain- temporal lobe cut away, showing the hippocampus. The hippocampus is the part of the brain responsible for long-term, declarative memories and for spatial memories.

HM was studied revolutionising the understanding of human memory. Provided broad evidence for the rejection of old theories & the formation of new theories on human memory & the underlying neural structures.

When HM died in 2008, neuroscientists were provided with the most extensively studied brain in history.

This anatomical treasure was entrusted to Dr. Jacopo Annese in the University of California, San Diego, who acquired 2041 slices of HM’s brain and made them available to study.

Dr. Annese is the founder of the Brain Observatory, an ambitious project which aims to collect as much information as possible on brain donors, in the hope that one day we will be able to track the connection between the brain structure and our life history.

THE HM PROJECT:http://thebrainobservatory.ucsd.edu/hm

YouTube: Clive Wearing - The Man With No Short Term Memory

A Bit of HumilityMind as information processor,

as computerRecognition, language, motor control, logic, etc.But there still remains: “The Hard Problem of Consciousness”Subjective experience, “what it’s like”

qualia - is a term used in philosophy to refer to individual instances of subjective, conscious experience. The term derives from a Latin word meaning for "what sort" or "what kind." Ex: the pain of a headache, the perceived redness of an evening sky.

A bit of humility, Part I“How it is that anything so remarkable as astate of consciousness comes about as aresult of irritating nervous tissue, is just asunaccountable as the appearance of theDjin, when Aladdin rubbed his lamp.” -- Thomas Huxley

Mechanistic conception of mental lifeBut what about humanist values?

★ free will & responsibility★ intrinsic value★ spiritual value?

Can they be reconciled?

Bit of Humility