lecture 3 Flashcards
define Cognitive neuroscience
The field of psychology that examines the brain mechanisms that give rise to mental functions (the psychological basis of cognition)
are there levels of analysis in cognitive neuroscience
oh yes, many
what are the Four philosophical views on the mind-brain link
¤ Interactionism
¤ Epiphenominalism
¤ Parallelism
¤ Isomorphism
what is Interactionism
says The mind and brain are separate entities
define Substance dualism
the mind and the brain are separate
substances that interact with one another
what view is Substance dualism part of
Interactionism
what question does Interactionism give rise to
how do an immaterial substance like the mind influence the physical body if they are so different?
what field of thought does Rene Descartes (early 1600’s) identify with
Interactionism
what did Rene Descartes suggest
¤ Suggested that this interaction occurs in the pineal gland in the brain
what was the problem with Descartes’ suggestion
¤ But it is still not clear how the mind – a non-substance – affects a physical object – the body
what is Epiphenomenalism
Mental thought is only ever the result of physical events (changes in the brain)
what does Epiphenomenalism believe about the mind and its impact on behaviour
The mind has no causal role in determining behaviour
is interactionalism popular today
no
who is associated with Epiphenomenalism
Thomas Huxley (1874)
what did Thomas Huxley believe about the brain and mental events
¤ “all states of consciousness in us … are immediately caused by molecular changes of the brain-substance …” ** modern neuroscience?
¤ Mental events are like steam (of a train) that contributes nothing to the work of a locomotive, it is simply a biproduct
summarize Epiphenomenalism
Anything that causally contributes to a physical event must itself be a physical event
what are criticisms of Epiphenomenalism
¤ Counterintuitive:
¤ Can’t explain the evolutionary purpose of the mind
¤ Can’t explain how the brain (physical) generates consciousness (mental events)
¤ Opposite problem to interactionism
what is Parallelism
The mind and brain are two aspects of the same thing
what is the difference between parallelism and dualism
¤ Another form of dualism but NO interaction between mind and brain ¤ Every event in the mind has a corresponding event in the brain
what is the criticism of parallelism
there is no explanation for this parallel structure
“I feel pain! –> I need to get my hand off this pot”
“Grab a hot pot handle –> Pull hand away”
what is Isomorphism
There is no simple point-for-point link between the brain, the physical world and mental experiences, but they are related
what does Isomorphism say the mind and the brain is linked by
A thought (the mind) is linked to the brain through a related pattern that is active for an associated physical experience
what is Isomorphism built on
A model-building theory
explain the A model-building theory that Isomorphism is buildt on
¤ The mind is an internal model of the external world and this is reflected in
the brain
¤ The brain pattern when perceiving a face is similar to the brain pattern when imagining a face
¤ The brain supports physical and mental events following similar (not the exact same) laws
¤ The notion that the mind and brain are separate but interacting entities is consistent with what approach to the relationship between mind and brain? A.) Interactionism B.) Isomorphism C.) Interactionism and Parallelism D.) Epiphenomenonalism
A.) Interactionism
what is The principle of neural representation
Our experiences are due to representations in our nervous system (each part of the brain has neurons that will contribute to different things as we experience them/as they are activated)
what does The principle of neural representation relate to
Functional specialization
what is Jerry Fodor’s modularity of mind hypothesis related to (which feild)
Functional specialization
what is Jerry Fodor’s modularity of mind hypothesis
¤The brain is composed of modules
¤Modules perform a very limited
number of tasks
¤Modules are inborn ‘compartments’ (innate)
¤A rationalist viewwhat are modules in Jerry Fodor’s modularity of mind hypothesis
Dedicated input systems needed for specific mental tasks
how do modules in Jerry Fodor’s modularity of mind hypothesis work
Processes lower-level information (e.g., color and orientation of visual stimuli)
¤ Localized to particular brain areas
¤ Domain specific
¤ Fast and work in a mandatory manner
The idea of modules opposes what view
the view that the brain is a general-purpose device
what is Jerry Fodor’s modularity of mind hypothesis an updated version of
phrenology
who came up with phrenology
Gall and Spurzheim (late 1700s)
what is phrenology
Parts of the brain correspond to mental
functions and personality characteristics
according to phrenology, when is the explanation for bumps and dents on people’s heads
Well-used mental functions cause the related brain area to grow and protrude (bump). Not used mental functions will cause the related brain area to shrink (dent)
¤ Use these bumps and dents on the skull to measure mental strengths and weaknesses
In it’s popularity, phrenology was used for many reasons which are what
¤ Spousal selection ¤ Criminal Reform
what is the issue with phrenology
¤ Problematic assumption: The more highly developed the function, the more visible the associated region is on the skull ¤ Size matters ¤ Problematic method for localizing functions ¤ Very speculative
who opposed functional specialization
Franz (1912)
what did Franz study
Studied the effects of ablation, destroying parts of an animal’s brain, on behavior
what hypothesis did franz test
Tested this hypothesis: If brain functions are specialized to a location, then destroying one area of the brain should be evident in very specific behavior impairment. The amount of damage across the brain shouldn’t matter
(he was against functionalism but studied it to try and disprove it)
Franz and his student Karl Lashley (1929) studied the effects of the amount and location of what kind of brain damage
frontal lobe damage in rats on a maze learning task
what did Franz and his student Karl Lashley find from the study
¤ Small brain lesions to specific regions didn’t impair performance
¤ Impairment on this task related to the size of the brain lesion
¤ Problems learning to navigate in the maze depended on the amount of brain damage and not the location of damage
what are the conclusions that Franz came to with his rat experiments
¤ Learning is directly proportional to the extent of brain damage not the location of the damage
¤ “Mental processes are due to the activity of the brain as a whole, and not individual parts”
¤ ‘Functional organization’ plays over cortical (locaitional?) cells
what 2 laws did Karl lushly come up with
(both anti functional specialism)
The law of mass action
The law of equipotentiality
what is The law of mass action
¤ Learning and memory (mental tasks) depend on the total
mass of brain tissue remaining
what is The law of equipotentiality
¤ Any part of the brain can do the job of any other part of the brain (within limits) ¤ Even if certain brain areas are specialized to perform functions, the brain is plastic and can over-ride this specialization
are there functional specialized parts of the brain
there are:
¤ Visual selective brain areas
¤ Parahippocampal place area: Recognizing or thinking about scenes/spatial layouts
¤ E.g., imagine walking through your home
¤ Motor selective areas
¤ Supplementary motor cortex: Performing or imagining motor movements
¤ E.g., imagine swinging a tennis racket
what are the 4 ways fo studying cognitive neruoscience
- Animal Models
- Behavioral (Psycho-physiological) measurements
- Neuropsychological Cases
- Neuroimaging techniques
explain how Animal models work
¤ Experimental brain lesions
¤ Make specific lesions to animal brains to examine the relationship between particular brain structures and cognitive function
what is a ver famous experiment regarding hippocampus lesion and rats
The Morris water maze task (1981)
explain the The Morris water maze task (1981)
¤ Learning: Rats are placed in a pool of water and learn the location of the platform
¤ Group Manipulation: Hippocampal lesions in one group, No brain lesions in another group (Control group)
¤ Memory Test: Rats are put back in the pool with the platform hidden
¤ Measure the ability of the rats to find that platform using their spatial memory
what did the Morris water maze show
Rats with hippocampal lesions don’t remember the location of the platform. The hippocampus is important for spatial navigation
whats the strength of using animal models
Provides a causal link between brain and behavior
what are weaknesses of animal models
¤ There are differences in brain structure and function across species
¤ Limits on generalizing findings
¤ Cannot provide a full understanding of human brain
¤ Can’t test the same ‘cognitive acts’
wha are Psycho-physiological measurements
Measure activity in the peripheral nervous system (i.e., not the brain) in response to things humans sense or imagine
what are the exact physiological measurements measured in psycho-physiological measurments
¤ Eye movements ¤ Skin conductance
explain how Skin Conductance/Response works
¤Skin conducts electricity, especially when it sweats
¤Sensing or remembering something that is arousing increased conduction
¤This response is a sensitive measure of arousal and mental activity
explain the Skin Conductance/Response experiment with verterans and PTSD
¤ Three participant groups ¤ Veterans with PTSD
¤ Veterans without PTSD ¤ Control Participants
¤ Two test conditions ¤ White noise
¤ Combat sounds
¤ Higher skin conductance in people with PTSD when hearing combat sounds
what are Neuropsychological cases
Learn about brain function by comparing the behavior of brain-injured patients to healthy control participants
what are Split brain patients
people who had their corpus callosum severed to alleviate epilepsy
what does the Corpus callosum co
¤ Allows the hemispheres to communicate with one another
¤ When cut, brain hemispheres of the brain cannot communicate with each other
¤ We can study the separate contributions of the left and right hemispheres to various abilities/tasks
Research with these patients (split brain) examined what
processing differences between the two hemispheres of the brain
The left hemisphere usually supports what
speech and language
The right specializes in what
in visual-spatial processing
Split brain cases: what is The classic finding
¤ Left hemisphere supports speech and language processing
¤ Without hemisphere communication, information to the right visual field (left hemisphere) can still be named and described in words
¤ Right hemisphere supports visual-spatial processing
¤ Without hemisphere communication, information to left
visual field (right hemisphere) cannot be verbally described
¤ Can still be expressed via visuo-spatial processes
what are the conclusions with the split brain findings
¤ No ‘module’ is damaged in these cases
¤ Connections between brain regions is just as important as the operations
¤ The brain isn’t like a computer – it is a network of interconnected computers
what are the 4 common Neuroimaging techniques
a. Electoencephalography (EEG)
b. Positron Emission Tomography (PET)
c. Functional Magnetic Resonance Imaging (fMRI)
d. Brain stimulation techniques
what does Electoencephalography (EEG) do
When the brain is put to ‘use’, it produces electrical activity that can be measured
¤ Event-related potentials (ERP)
EEG measures activity in a large group of neurons at certain times
¤ Links electrical signals in the brain and onset of a a cognitive task
EEG provides information about what
activity in the brain at certain time periods
give an example of how EEG is used
¤ Example
¤ Present words that people previously learned
¤ Look at ERPs when people recognize a word shown on a computer screen compared to words that have been forgotten
what are the strength and weaknesses of EEG
¤ Great at giving timing information (temporal resolution) but not location information (spatial resolution) about brain activity
¤ Lots of things can affect ERP signals
¤ This means a researcher needs to collect a lot experimental trials
¤ Limits the kind of studies you can run
what is Positron Emission Tomography (PET)
3-D images of how the brain is working
how does a PET work (4 steps)
- A radioactive tracer is injected into the blood stream
- Radioactive tracer intermingle with molecules in the blood stream
- This mingling releases isotopes over time that are picked up by the PET scanner
- The PET scanner tracks where this release occurs to indicate which brain areas are ‘active’
what is PET useful for
Useful for clinical purposes to give evidence for how certain conditions affect brain function
what are weaknesses of PET
¤ No structural information
¤ There is a limit to the amount of radiation a person can handle
what are the 2 types of Magnetic Resonance Imaging (MRI)
Structural MRI
Functional (f)MRI
what information can you get from Structural MRI
¤ Information about shape, size, and integrity of
structures in the brain
¤ Good to detect structural anomalies
what info can you get from Functional (f)MRI
¤ Information about activity in the brain
¤ An indirect measure: Measures blood flow, not neural activity
how does fMRI work
¤ Does not involve radioactive tracers
¤ A magnet that detects changes in
oxygenated blood
¤ This indicates neural activity
¤ Active brain areas need oxygen
¤ The different levels of oxygenated and de-oxygenated blood is used to create an image of brain activity during a taskwhat did fMRI prove (about memory)
¤ Compared activity when people recognized previously studied items versus seeing new items
¤ Activity when remembering
¤ fMRI scans revealed activity in the hippocampus
¤ This is an region important in memory
what are strengths of fMRI
¤ Non-invasive
¤ Good spatial resolution
¤ About a 1000 papers published per month
what are weaknesses of fMRI
¤ Poor temporal resolution
¤ It is hard to determine the order of brain activity
¤ An indirect measure of neural activity that is very noisy …
what is The dead salmon study and what was the point of it
¤ An fMRI study that made it appear that a dead salmon was ‘thinking’ about photographs
¤ Shows that there is a lot of noise in the fMRI signal
¤ fMRI Researchers must be careful in their analysis and interpretation
what is brain simulation
¤ Involves modulating brain activity by inducing neural disorder or enhancement
¤ A reversible ‘virtual’ human lesion
¤ Stimulate (enhance) brain activity
what is Transcranial Magnetic Stimulation (TMS)
Transient disruption (or activation) of brain activity by applying a focal magnetic field (how brain simulation is done)
what did brain simulation/TMS prove
TMS may improve memory
what experiment was conducted to conclude that TMS may improve memory
¤ Participants did a face-word memory test
¤ Over five days, some participants received TMS to memory networks; other
participants received no TMS (sham)
¤ All participants did another face-word memory test
¤ Participants who had TMS improved memory scores by up to 25%
¤ Participants who did not get TMS (sham) showed on improvement to
memory
what is Deep brain stimulation (DBS)
¤Implant tiny electrodes in the brain to send an weak and constant electrical current to targeted regions of the brain that are affected in certain conditions
does Deep brain stimulation (DBS) work
Shown to reduces symptoms in cases like Parkinson’s disease (motor symptoms) and depression (mood symptoms)
is Deep brain stimulation (DBS) fully understood
nope… still trying to understand it
what are the weaknesses of brain simulation
¤ It is difficult to determine the correct intensity of stimulation
¤ It is still not clear how to stimulate or inhibit activity in the brain?
¤ Difficult to localize activity
¤ The stimulation has very broad effects on the brain so it hard to target on region
give a summary of EEG
Measure electrical activity with good temporal resolution
give a summary of Positron Emission Tomography (PET)
Use of radioactive tracers in scanner but not commonly used
give a summary of Functional Magnetic Resonance Imaging (fMRI)
¤ Examine oxygen in blood flow with good spatial resolution
give a summary of Brain stimulation techniques
¤ Virtual lesions / modulation
How does functional magnetic resonance imaging (fMRI) measure brain activity?
A. magnetic charges
B. electrical activity in certain brain regions
C. radioactive substance that mingles with the blood and circulates to the brain
D. detects the flow of oxygenated blood
D. detects the flow of oxygenated blood
