Lecture 1 Flashcards
Consciousness conclusion
We still dont know what consciousness is or how it works. It seems to involve a host of neural processes and some magic or something we dont get.
Definition consciousness
the state or quality of awareness - awareness of your thoughts, perceptions, memories and feelings
Why do neuroscientists believe that consciousness and the mind arise from neural processes?
Do we have an answer?
Consciousness can be changed by physical or chemical changes within the brain (damage or drugs).
Studies have not been conclusive but have taught us some things
The frontal lobotomy
Cot of parts of the prefrontal cotex with a giant pick
Same rational as gangrene; cut out the affected part
Makes people docile
Was popularized by travelling doctors
Nobel prize awarded
20000 done in the USA
Generalized epileptic seizure
Uncontrolled excitement on both sides of the brain
Split-brain operation
Designed to lessen epilepsy
cut corpus callosum and the posterior and anterior commisures
Generally works for epilepsy but unacceptable sides
Cerebral hemispheres are important for
ability to consciously process sensory information, purposefully move our bodies
contralateral arrangement
Eye organisation
right visual field to left brain
left visual field to right brain
Corpus callosum
bridge between two hemispheres
allows for each to know what the other is doing
if cut, cannot
can still send signals down to midbrain, hindbrain and spinal chord to control muscles
History of the spit-brain surgery
in 1939, 10 patients had surgery in Rochester, NY
Doc said this was an amazing success
Scientists re evaluated them
1 - claims exagerrated
2 - Corpus callosum not impoirtant for anything
Roger Sparry at Caltech did not agree as he had done this to animals and they produced characteristic effects. He thought there was probably still some bridges intact.
He was invited to do pre and post surgery investigations at Caltech when a surgeon there was going to do it.
Split-brain patients reported
feeling the same after
but having their left hand misbehaving as if it were not under their conscious control. This implies the right hemisphere is acting out
Right hand did not
Viki
issues with right hand fighting her in supermarket and when getting dressed. After a year got better. Common for these patients
Split-brain patients - touch
Cannot ID objects in left hand by touch alone
Did not bother them as very rare that this happens so might go unnoticed.
Split-brain patients - vision
When shown object in their left visual field only, cannot verbalize what they have seen. They are unconscious of what their right brain deals with
They compensate behaviorally and their hemispheres adapt
Motor is coordinated at the subcortical level so with practice can do it
Language and brain
right not sophisticated with language
Can understand simple qs directed to right brain - it retains a small dictionary and can understand simple letters. The left hand can sometimes over write simple words.
Can still draw though
Split-brain experiments - Questions
Have person fixate on a point
Present an object either to the left or the right of the focal point for 200ms so that it is not long enough to focus on it.
Ask if object is present
1) if the object is in the left visual field they say no because this goes to the right and so the person is unaware
2) if the object is in the RVF, they say yes as this goes to the left hemisphere which is aware
3) if you show two objects, one to the left and one to the right of the focal point and ask if they are the same, the participant will say they do not know.
Split-brain experiments - objects and words
If you put two words either side of the focal point, like KEY to the left and RING to the right and ask them what the word is, they will say RING as this goes to the left hemisphere. IF however you ask them to take the object that corresponds to the word on the left, using touch (in this case KEY), using their left hand, they will find a key as the right hemisphere has seen the world key.
This will be a great shock to them and they will not know why they did it. They will believe their hand probably found a ring as that is the word they are conscious of.
Post-hoc answers
When asked to explain why people did what they did after their right brain is prompted to do something (that is outside of their conscious control), they make something up that justifies it.
Eg, Right brain prompted to laugh, person says he laughed cos they’re always testing him and its funny
Gazzaniga’s Interpreter Theory
Our behaviour is controlled by inconscious processes and the consciousness of our left brain is just making narratives to make sense of the world. Left-brain consciousness doesn’t influence behavior, it just weaves things together to make a story that has meaning.
Therefore free will is an illusion. Consciousness is just storytelling. Since storytelling relies on language, consciousness must only located in the left hemisphere.
It is an epiphenomenon
Scientific revolution and acceptance of determinism
As science grew during the revolution, we have become comfortable accepting that the world is just an unbroken chain of cause and consequence.
Descarts
In the middle of the sci revolution, Descartes started questioning everything. If our perceptions are misleading, what can we trust?
He decided “I think, therefore I am”
The only thing we can know to be true is that we have the ability to think and for this to be true, Descartes argued, consciousness must be real because we must be conscious to exist.
Important outstanding questions in the field
1) how do we feel things
2) what is thinking and how does it work?
3) What is mental illness
Profs attitude to interpreter thinking
Its wring
We do not know what consciousness is yet, we should first understand that then work out free will
What we know (4 things)
What brain is made of and how things work at the cellular level
How neurons communicate
How sensory stimuli is transduced and initially processed
The last few cells in the motor system pathway
What we dont know (few cells deep)
after a few cells deep we have no idea what is happening or how info is processed.
Very limited understanding of the neural bases of emotion, cognition, consciousness, decision making etc
Dali Lhama and Jill Bolte Taylor
Lama meditates to achieve higher awareness
Jill had a stroke that disabled her language processing on the left hemisphere and found herself feeling more aware until her left brain came back online.
Possible that consciousness does not require language
Others disagree and say they’re totally intertwined.
