Cognitive Neuroscience Test 1 Flashcards
Phrenology
Phrenologists look at high level functions localized in specific areas. they look at SPECIFIC areas of the brain and mapping specific functions for specific brain areas
Flouren’s’ Aggregate field theory
The whole brain participates in behavior; there are no specific functions in the specific brain regions
Broca’s Area
speech production (found this through studying damage to the area)
Association cortex
Not sensory or motor
Receive inputs from many areas
Contains cells that may be activated by more than one sensory modality
Specific functional roles
Brodmann areas (what are they; not the specific numbers)
52 distinct areas based on cell structure - multiple cells looked the same so he grouped them together. Even though the areas were only done by how they look and not how they function, it was found that many that look the same, have the same functions- for example, all the cells in Broca’s area look the same so without trying, he showed where Broca’s area wa
Cerebellum
(translation- “little brain”)
The small area hanging off the back of the main brain area
Maintains posture and smooth, coordinated movements
Does not control movement directly
Combines information from sensory inputs describing body position to support smooth coordinate movement
Cerebellum Volume
tells us a lot!
Not strongly related to cortex size
Varied across different species
Species with large cerebellum volume have complex forelimb control (doing things with hands, paws, beaks, etc.)
i.e. some rodents, some large-brained birds, elephants, and some primates
This shows that the cerebellum is important for integrating necessary sensory motor information
Interestingly, dolphins have the largest cerebellum
Default mode network
Set of brain regions that are active when participant is ‘resting’
Not performing a task
These areas become deactivated when participant is performing a task
These areas are involved in memory, future planning, and self referential processing. So, they become active during resting AND tasks that involved these things.
Double dissociation
Patient 1 has damage in Area X and is impaired at Task A but not Task B
Unclear whether Area X is specifically involved in Task A
It is possible that damage to any area causes Task A but not Task B impairment
AND patient 2 has damage in Area Y and is not impaired at Task A but is impaired at Task B
Much more likely that Area X is specifically involved in Task A
Damage to Area Y does not cause Task A impairment
DTI
a technique that detects how water travels along the white matter tracts in the brain
Used for images of axons
Uses traditional MRI scanner
- Sensitive to protons in water rather than tissue
Measures motion of water in axons
- Motion of water is restricted by myelin
- More likely to flow in direction of axon than perpendicular to axon
Can be used to image axons in the brain
Fasciculus
a bundle of axons in the brain
EEG
Electrical potentials from populations of active neurons are measured through the scalp
Disks are placed on the scalp and measure the electric signal coming from the brain. It is flexible- people can move around
Electrical activity changes based on internal state
ERP
Align EEG signal with an external event(Stimulus or response)
- Average over many trials of same type (variation cancels out)
Identify relevant waveforms
- N100 (negatively deflecting waveform occurring 100ms post event onset)- Indicates early stimulus processing
- P300 (positively deflecting waveform occurring 300 ms post event onset- Indicates response to low-probability event)
EEG/ERP pros cons
Pros- have good temporal resolution
Can tell the difference between events that occur 1 ms apart
Cons - poor spatial recognition
Cannot tell where electrical activity is generated
fMRI
Has replaced PET scans for the most part
Similar to MRI
Radio waves perturb proton orientation
When radio waves are turned off, the protons realign with the magnet
Rebound is measured by detectors and produces 1 image.
Difference between MRI and fMRI? Focus on protons in hemoglobin (instead of those in gray/white matter)
Hemoglobin- the oxygen-transport protein in blood
Active areas need blood AND oxygen, so where there is more oxygen, there is more activity. This is why it has replaced PET scans for the most part)
Blood oxygen level dependent (abbreviated BOLD) signal
Good spatial resolution (can distinguish activity locations if they are 1-3 m3 apart)
Has okay temporal resolution (can distinguish activity events that occur 1-2 seconds apart)
A limit- same as MRI, each layered image of the brain takes time.
Functional connectivity
Looking at the connections of the whole brain and how it functions together rather than just one place
Brain areas work together in interconnected networks
- There is a way to examine this with connectivity maps (connectomes) which reveal brain areas that function together
- Maps created by correlating activity in different brain regions over time
This technique requires ‘okay’ spatial and temporal resolution to do well
grey matter
Gray matter volume increases until 6-7 years and then decreases by 5% per decade
Grey matter makes up the outer most layer of the brain
Gray matter is made up of neuronal cell bodies
MEG
Similar to EEG/ERP except measures changes in magnetic fields instead of changes in electricity
MEG traces aligned to event and averaged across trials
Event-related fields (ERFs)
Inverse dipole modeling
Solutions more accurate than for ERP because magnetic fields are not distorted as passing through tissue, skill, and scalp
Good temporal resolution (milliseconds)
Good spatial resolution
Except that locations are modeled rather than observed. Not looking at it, using math to model it
Motor cortex
eh directs movements
MRI
How does this work?
MRI’s measure the distribution of protons in gray/white matter
It does this through magnetic imaging and measuring the difference in timing between protons (we don’t need to know this for tests)
