Chapter Two - Cognitive Neuroscience Flashcards
What are the 2 types of experiments involved in studying the mind?
- behavioral experiments
2. physiological experiments
What is cognitive neuroscience?
- study of physiological basis of cognition
- understanding of nervous system + individual units that comprise that system
What are examples/methods of the behavioral approach?
- measures relationship between stimuli and behavior
- RT
- proportion of errors
- verbal protocols/self report
What are examples/methods of the physiological approach?
- measures relationship between physiology and behavior
- EEG/ERP
- heart rate, skin conductance etc.
- PET
- fMRI
What are the variables of the memory consolidation study?
independent:
group 1: learned words right before sleep
group 2: learned words long before sleep
dependent: memory (percent forgotten) 2 days later
What were the behavioral results of the memory consolidation ex.?
awake group showed higher percent of forgetting
What were the physiological results of the memory consolidation ex.?
- differential brain activity in the hippocampus
- increase in sleep group
- decrease in awake group
What did anatomists first believe the structure of the brain to be?
continuous nerve net
What did Camillo Golgi find in 1870 with better staining techniques?
structure of a neuron
What method did Santiago Ramon y Cajol use?
-Golgi’s staining technique on tissue from brains of newborn animals
What was Ramon y Cajol’s major idea?
neuron doctrine
What is the neuron doctrine?
- individual cells transmit signals in nervous system
- cells not continuous with other cells
What are Caja’s 4 major findings?
- synapses
- neural circuits
- receptors
- specialized cells to create, receive + transmit info
dendrites
- multiple branches reaching from cell body
- receive info
cell body
- contains mechanisms to keep cell alive
- contains nucleus
myelin sheath
- fatty tissue
- electrical insulator
- facilitates propagation
nodes of ranvier
- gaps in myelin
- regenerates AP
synapse
- junction between nerve cells
- diffusion of NT
axon
-tube that transmits AP
What are microelectrodes?
-small shafts of conductive solution that pick up electrical signals
What are the 2 parts of a microelectrode?
- recording electrode: recording tip inside nueron
2. reference electrode: located some distance away
What is resting potential?
-difference in potential between 2 electrodes when neuron is not firing
(-70 mV)
What is the voltage of a neuron when an AP fires?
+40mV
What is an action potential?
-mechanism through which info is transmitted in the nervous system
Each action potential travels down axon without changing its _____ or ______
height or shape
what is a synapse?
-space between axon of one neuron + dendrite of another
What happens when the AP reaches the end of the axon?
- synaptic vesicles open
- release chemical NT
What do NT do once released?
- cross synapse
- bind with receiving dendrites
What are neurotransmitters?
-chemicals that affect electrical signal of receiving neuron
What is an excitatory NT?
increases chance neuron will fire
What is an inhibitory NT?
decreases chance neuron will fire
do all signals lead to action potentials?
no
When does an action potential result?
-only if threshold level is reached
rate of neural firing is related to _____ of stimulation which in turn is relation to the_____ of the ______
- intensity
- magnitude of the experience
Is everything a person experiences based on direct contact with stimuli?
- no
- representations in person’s nervous system
What did Hubel + Wiesel study?
representation in one neuron
What are feature detectors?
neurons that response best to a specific stimulus
EX: orientation, movement, lenght
What did Charles Gross do?
-performed experiment in which he recorded form single neurons in monkey’s temporal lobe
What did Charles Gross find?
- found neurons that refused to respond to any “simple” stimuli of lines, circles etc.
- neuron fired in mistake to hand shadow
- found neurons that only respond to faces
What is the difference between neurons in visual cortex + neurons in temporal lobe?
visual cortex: simple shapes
temporal lobe: complex geometrical stimuli
What is hierarchical processing?
-ascension from lower to higher levels in brain corresponds to perceiving objects that move from simple to higher levels of complexity
What is sensory coding?
how neurons represent various characteristics of the environment
What is specificity coding?
- representation of a specific stimulus
- by firing of specifically tuned neurons specialized to just respond to a specific stimulus
What is population coding?
- representation of a particular object
- by the pattern of firing of a large number of neurons
What is sparse coding?
- when a particular object is represented by a pattern of firing only a small group of neurons
- majority of neurons remaining silent
what does localization of function mean?
specific functions are served by specific areas of the brain
What is the cerebral cortex?
- 3mm thick layer that covers the brain
- contains mechanisms responsible for most of our cognitive functions
ipsilateral
same side
contralateral
opposite side
bilateral
both sides
unilateral
one side
proximal
close to trunk
distal
far from trunt
efferent
away from
afferent
towards
What are 3 planes of bisection?
- coronal
- axial
- sagittal
What is grey matter?
contains nerve cell bodies
what is white matter?
contains myelinated axons
What are the 4 lobes?
frontal - reasoning, planning, language
parietal - integrating sensory info, touch, temp
temporal - auditory, language, memory, smell
occipital - visual
Broca’s aphasia
- language production impaired
- left frontal lobe
Wernicke’s aphasia
- language comprehension impaired
- left temporal lobe
What did studies of soldiers in WW1 show?
-damage to occipital lobe results in blindness
What is the result of damage to the left part of visual cortex?
-blindness in upper right part of visual space
What is prosopagnosia?
-an inability to recognize faces
What is alexia?
inability to recognize text, read
What is semantic agnosia?
object blind
What is tactile agnosia?
inability to feel touch
What is double dissociation?
- damage to one part of brain causes function A to be absent while function B is present
- damage to another area causes function B to be absent while function A is present
What does double dissociation allow us to conclude?
- function A and B served by different mechanisms
- operate independently
What is a benefit of double dissociation?
-allows us to identify functions that are controlled by different parts of the brain
How does double dissociation work with faces?
- can’t recognize faces (function A)
- can recognize objects (function B)
What is MRI?
- magnetic resonance imaging
- images structures within brain
What is an fMRI?
- functional magnetic resonance imaging
- determines neural activity/functioning of the brain via blow flow
How is blood flow measured?
- oxygen in blood carried by hemoglobin
- hemoglobin contains a ferrous molecule (iron)
What happens in areas of activity during an fMRI?
- more oxygen used
- more iron
- more magnetic signal
What are 3 advantages of MRI?
- good spatial resolution
- no radiation
- differentiates tissues
What are 3 disadvantages of MRI?
- expensive
- can’t have metal
- takes longer (than CT)
What does an fMRI measure?
- Blood Oxygenation Level Dependent (BOLD)
- measures probabily that region has increased blood flow according to Z/Tscores
- quantifiable difference
- NOT SEEING ACTUAL BLOOD FLOW
What are 3 types of neuroimaging experimental designs?
- block design
- event-related design
- resting state
What does the FFA respond to?
- fusiform face area
- responds specifically to faces
Where is the FFA?
temporal lobe
What is happens when there is damage to the FFA?
prosopagnosia
What is the PPA?
- parahippocampal place area
- responds specifically to places (indoor/outdoor scenes)
Where is the PPA?
-temporal lobe
What is the EBA?
- Extrastriate body area
- responds specifically to pics of bodies + parts of bodies (not faces)
Where is the EBA?
-occipital lobe (visual cortex)
What is distributed representation?
-specific functions processed by many different areas of the brain
What is the two-stream hypothesis?
ventral + dorsal pathways
What is the ventral pathway?
- “what” pathway
- processes identity of perceived object
What ist he dorsal pathway?
- “where pathway”
- processes location of perceived object
What are neural networks?
- groups of neurons/structures
- connected + together allow for overall experience
What is an example of a neural network?
- pain network
a. locational + sensory aspect
b. emotional aspect
c. significance
d. attentional aspect
e. memory
What is functional connectivity?
-regions in brain that have similar patterns of activity over time
What is structural connectivity?
-neuroanatomy, measures connectivity of neurons
What is MVPA?
- multivoxel pattern analysis
- applies machine learning techniques to neuroimaging data
- looks at distributed patterns of neural activity
What are 3 things that MVPA allows us to do?
- decode percepts/thoughts (mind reading)
- decode brain patterns
- characterize distributed representations
What are 5 steps to MVPA analysis?
- acquire brain data in different conditions
- generate brain patterns of activity across voxels
- label patterns
- train a classifier
- apply classifier to new patterns
What are 3 examples of MVPA?
- identifying emotion
- identifying neural markers of mental illness
- new understanding sensory processing in brain
What are 3 common pitfalls of neuroimaging analysis?
- multiple comparison problems
- reverse inference
- voodoo correlates + double dipping
