cerebral asymmetry and consciousness (L4) - Matt Roser Flashcards
What historical views are discussed in the lecture regarding consciousness?
Dualism and monism
What is Cartesian Dualism?
The view that mind and body are separate realms
What did Descartes contribute to psychology?
Formulated ideas on the nature of the mind and control of behavior
According to Descartes, what is the essence of our being?
Mind is essential to our being in a way that body is not
What did Aristotle believe regarding the soul?
The soul is the essence of being with no distinction between mind and body
What was the pneumatic theory of the brain proposed by Galen?
Involved ventricles and animal spirits
What did Descartes’ ‘De Homine’ outline?
The role of ‘animal spirits’ in reflex action
What did Descartes imply about human behaviors?
Most human behaviors can be understood through the investigation of animal behavior
What is the relationship between mind and body according to Descartes?
Mind and body are separate, with the body being a mechanical system
What does the term ‘Cogito, ergo sum’ translate to?
‘I think, therefore I am’
What is the ‘Cognitive Revolution’?
A movement in the 1960s rejecting dualism and adopting a monist/materialist stance
Fill in the blank: Modern cognitive neuroscience suggests we may be just ______ that construct the illusion of a mind.
bodies
What is consciousness?
The ability to report on one’s mental states and processes
processes and states like being awake, alertness, attention, reportable states and self-awareness
What are the three tractable characteristics of consciousness?
- Operationalized
- Implementation
- Adaptivity
What phenomenon is associated with blindsight?
Residual visual function and consciousness despite damage
What is the significance of brain lesion patients in understanding consciousness?
They provide evidence against Descartes’ intuition about the enduring nature of the mind
True or False: Descartes believed the mind and body were fundamentally the same.
False
What does the global neuronal workspace model suggest about consciousness?
Consciousness is a global pattern of activity across the brain
What is the main argument against Descartes’ view on the unity of the mind?
Evidence from brain lesions suggests the mind is not unitary
What does the term ‘qualia’ refer to?
Subjective experience
What is the main distinction between access consciousness and phenomenal consciousness?
Access consciousness is reportable; phenomenal consciousness is subjective experience
What is cerebral asymmetry?
Anatomical and functional differences between the two hemispheres of the brain
It involves how cognitive processes are lateralized in the brain.
What separates the two hemispheres of the brain?
The Longitudinal / Sagittal fissure
This fissure divides the left and right hemispheres anatomically.
What connects the two hemispheres of the brain?
Commissures, including the Corpus Callosum and Anterior Commissure
The Corpus Callosum contains over 200 million axons, 95% of which are myelinated.
What are homotopic, heterotopic and ipslateral connections?
Connections between corresponding areas of the two hemispheres
These connections are strictest between primary cortex areas.
What is the role of the Planum Temporale?
Auditory processing supporting language
It shows anatomical asymmetries that are important for language comprehension.
How can each hemisphere be tested?
Using lateralized visual presentation and dichotic listening
These methods reveal differences in processing between hemispheres.
What is commissurotomy?
Section of the interhemispheric commissures
This procedure is often performed to prevent seizure spread.
What is disconnection syndrome?
Condition where each cerebral hemisphere is disconnected from the other at the cortical level, preventing spread of seizure activity from one side to the other
-shown in sperry, 1982 split brain experiment
It results in unique behavioral characteristics in split-brain patients.
What does the split-brain experiment reveal?
Hemispheric integration via commissures, and the independence of each hemisphere
-more specifically, subcortical commissures & limited transfers, partial callosotomy & specificty of transfer
Controlled experiments can demonstrate how each hemisphere functions separately.
What is the significance of the right visual field (RVF) in split-brain patients?
Faster and more accurate naming by the left hemisphere
This indicates that language centers are predominantly left-hemispheric.
What cognitive processes are superior in the right hemisphere?
Construction, detecting offsets, orientation, mirror reversal, and perceiving degraded stimuli
-extracts higher level percepts from the visual array
The right hemisphere is involved in higher-level perceptual tasks.
What happens during unilateral brain damage?
Disruption of local or global representation depending on the side affected
Left brain damage disrupts local representation; right brain damage disrupts global representation.
What is the left-hemisphere interpreter role?
The left hemisphere’s tendency to confabulate and look for patterns
This reflects the left hemisphere’s role in verbal and analytical tasks.
What is the effect of task difficulty on hemispheric cooperation?
Increased task difficulty leads to a bilateral advantage
Performance improves when tasks require bilateral processing rather than unilateral.
Fill in the blank: The _______ allows for fast intrahemispheric processing necessary for functions like language.
divided brain
True or False: Hemispheric differences are absolute and do not change with task demands.
False
Hemispheric differences are relative and fluid, changing with stimulus and task requirements.
what is the anatomy of the hemispheres?
seperated by longitudinal/sagittal fissures
-connected by commissures
what is anatomical asymmetry?
anterior RH and LH overlap midline
-sylvian fissure: ascends more anteriorly in the right hemisphere, longer in left hem
in which regions of the brain, does anatomical asymmetry occur?
-Planum Temporale
-Wernickes Area
-Auditory processing supporting language
what is visual and auditory input predominantly?
contralateral
why is FMRI useful in testing each hemisphere?
reveals lateralisation of the main brain regions involved in cognitive processes
how is the split brain tested?
-each side of visual space projects to opposite side of the brain
-technique is to flash info quickly to one or othr side before eye movements can occur
-allows properties of each side of the brain to be assesed
what is the specificty of transfer?
Anterior hemisphere - semantic transfer
Central hemisphere- Motor transfer
Posterior hemisphere - sensory transfer
why do we have a divided brain?
more efficient use of cortical space
allows for fast processing, necessary for functions like language
what is the modern cognitive neuroscience view?
we may just be bodies that construct the illusion of a mind
what did Moutoussis & Zeki, 2002 find?
differences in brain processes for consciously perceived vs non percieved stimuli
-concluded from brain activitiions in respond to stimuli that are not consciously perceived
-colour reversed faces are displayed seperately to the two eyes -> binocular fusion occurs and subjects report seeing onlt the colour that results from the combination of the two stimulus colours
what do models of consciousness show?
activations associated with percieved stimuli were many times more intense than those seen with unpercieved stimuli and were accompanied by activity at additional sites
-only reach consciousness if it is integrated into a large scale system of cortical activity
-attentional amplificatino leads to interaction of modular processes allowing information to be mainintaned and influence other processes
what is suggested by lesion patients?
fractionated consciousness
-damage reduces function and it can also reduce awareness of that deficit
