CHAPTER 2 COGNITIVE NEUROSCIENCE Flashcards
what is cognitive neuroscience?
the study of the neurophysiological basis of cognition
describe the levels of analysis term
refers to the idea that a topic can be studied in a number of different ways
looking at the processes behind behaviour as looking under the hood of the car is an analogy of?
levels of analysis
what kind of experiences can involve chemical processes? what kind of processes?
initial; creating electrical signals in neurons
what happens when individual brain structures are activated?
multiple brain structures are activated
chemical and electrical processes are stored into experiences which forms a_____
memory
what do neurons do?
create and transmit information about experiences and knowledge
what would 19th century anatomists do to increase the contrast between different brain tissue types?
applied special stains
what is the nerve net theory?
states there is a continuous network providing a complex pathway for conducting signals uninterrupted
in 1870 who developed a staining technique?
Camillo Golgi
what was Golgi’s technique?
stains created pictures in which fewer than 1% of the cells were stained to stand out from the rest using a single slice of brain tissue
who used the Golgi stain and studied tissues from newborn animals because of their lower density?
Ramon y Cajal
what did Cajal discover?
the nerve net is not continuous but is made up of individual units connected together
what was Cajal’s neuron doctrine?
the idea that cells transmit signals in the nervous system and that these cells are not continuous with other cells as proposed by the nerve net theory
what is the cell body of a neuron?
the metabolic center of the neuron: contains mechanisms that keep the cell alive
what are the dendrites of the neuron?
projections from the cell body that receive signals from other neurons
what are the axons of the neuron?
long processes that transmit signals to other neurons
what are Cajal’s 3 conclusions about neurons?
- small gap between axons of one neuron and dendrites of another neuron is the synapse
- neurons are not connected indiscriminately to other neurons but to form connections to specific neurons to form neural circuits
- in addition to neurons in the brain there are neurons that receive information from the environment using receptors
what was needed to make small electrical signals generated by neurons visible
electric amplifiers
in the 1920s what did Edgar Adrian use?
microelectrodes
what are microelectrodes?
small shafts of hollow glass filled with a conductive salt solution that could pick up electrical signals at the electrode tip and conduct the signals back to the recording device
what is the resting potential inside the cell in comparison to the outside
-70mV
what is a resting potential?
the charge on the inside of the neuron when there are no signals in it
what is a nerve impulse?
when the neuron receptor is stimulated and it travels down the axon
what is the membrane potential inside the axon compared to the outside during a nerve impulse?
+40mV
what is an action potential?
when the nerve impulse continues and the charge inside reverses its course and starts to become negative again until reaching resting potential again
what is a special property of an action potential?
it travels down the axon without changing height or shape making them ideal for sending signals over a distance
what is released at the synapse?
neurotransmitter
what is a neurotransmitter?
a chemical responsible for transporting a signal across the synapse
how did Adrian study the relationship between nerve firing and sensory experience?
measuring how the firing of a neuron from a receptor changed while applying more pressure to skin
what did Adrian observe from his nerve firing and sensory experience experiment?
the height and shape of the remained the same and the rate of firing increased as pressure on the skin increased
the overall rate of neural firing is related to the intensity of the stimulus relating to the magnitude of the experience
the quality of experience is represented in neural firing by ….
the activation of different neurons and areas in the brain
what do representations in the mind refer to?
everything we experience
what is the principle of neural representation?
states that everything a person experiences is based on representations of the person’s nervous system
what were the 2 discoveries made from recording neurons outside the visual receiving area?
- many neurons at higher levels of the visual system fire to complex stimuli like patterns and faces
- a specific stimulus causes neural firing distributed across many areas of the cortex
is memory determined by a single memory area? why?
no
there are a number of areas involved in creating a memory and remembering later
who presented visual stimuli to cats and determined which stimuli caused specific neurons to fire?
David Hubel and Thorsten Wiesel
what are feature detectors?
neurons that respond to specific stimulus features such as orientation, movement, and length
what is experience-dependent plasticity?
when the structure of the brain is changed by experience
what is the extrastriate body area?
activated by pictures of bodies and parts of bodies
who analyzed how voxels responded to different objects and actions in films by having a participant sit in a brain scanner while watching a film
Alex Huth
what is the central principle of cognition?
most of our experience is multidimensional
what are the 5 aspects of a face we respond to?
emotional
where the person is looking
how the parts of the face move
how attractive the face is
whether a face is familiar
what is distributed representation?
the idea that perceptions activate many areas in the brain
what are the 2 modern language pathways?
- processing sounds, speech production and saying words
2. understanding words
what are neural networks?
interconnected areas of the brain that can communicate with each other
what are the 4 principles of neural networks?
- complex structures called networks form the brain’s information highway
- within structural pathways there are function pathways serving different functions
- the networks operate dynamically which mirrors the dynamic structure of cognition
- there is a resting state of brain activity so parts of the brain are active all the time even when there is no cognitive activity
what is structural connectivity?
the brain’s wiring diagram that is created by nerve axons that connect different areas of the brain
what is track weight imaging?
detects how water diffuses along the length of the nerve fibers
what is connectome?
indicates the structural description of a network’s elements and connections forming in the brain
the wiring diagram of neurons resembles ..
how fingerprints are different for every person
what is functional connectivity?
helps determine what parts of the neural network are involved in different functions
how is functional connectivity determined?
by the extent to which neural activity in 2 brain areas are correlated
functional connectivity uses what?
resting-state fMRI
what is resting-state fMRI?
measures a response while a person is at rest
who coined the term resting-state functional connectivity?
Bharat Biswal
who did a kitten/cat experiment to demonstrate experience-dependent plasticity?
Blakemore and Cooper
what did Blakemore and Cooper observe in their experience-dependent plasticity experiment? (2)
kittens whose cortex contains vertically sensitive neurons the kitten would only perceive verticals
perception is determined by neurons that fire to specific qualities of stimulus
what were Blakemore and Cooper able to conclude about experience-dependent plasticity?
the visual cortex is apart of an early stage of visual processing
vision depends on signals sent from the visual cortex to other brain areas
who recorded neurons in a monkey’s temporal lobe and presented a variety of stimuli to anesthetized monkeys
Charles Gross
what did Charles Gross observe in his complex stimuli experiement?
neurons would respond to specific stimuli and not to others
neurons in the visual cortex send their axons to higher levels of the visual system where they respond to more complex stimuli
what was Charles Gross able to conclude about complex stimuli?
signals are sent to higher areas of the visual system to be processed and their neurons respond to more complex stimuli
what is hierarchical processing?
the progression from lower to higher areas of the brain
what is sensory coding?
refers to how neurons represent various characteristics of the environment
what is specificity coding?
the idea that an object could be represented by the firing of a specialized neuron that responds to only that object
what is population coding?
the representation of a particular object by the pattern of firing many neurons
what is special about population coding?
large number of stimuli can be represented because a large group of neurons can create a huge number of different patterns
what is sparse coding?
occurs when a particular object is represented by a pattern of firing only a small group of neurons and the remaining neurons are silent
what was found from recording the frontal lobe of patients undergoing surgery for epilepsy?
stimulation of neurons before or during the procedure allows one to determine the exact layout of the person’s brain
are representations of memories different from representation of perceptions?
yes
how do representations of memories and perceptions differ?
- perceptual neural firing is associated with what occurs with a stimulus present
- memory neural firing is associated with info about the past that has been stored in the brain and is more involved in population and sparse coding
what is localization of function?
specific functions are served by specific areas of the brain
what functions are served by the cerebral cortex?
cognitive functions
the ___ is wrinkled covering and looking at an ____
cortex; intact brain
what is neuropsychology?
the study of behaviour of people with brain damage
in the early 1800s what was known as cortical equipotentiality?
the idea that the brain operated as an indivisible whole as opposed to specialized areas
who said that those who suffer from brain damage due to strokes can cause disruptions of blood supply to the brain
Paul Broca
what is Broca’s aphasia?
slow, labored, ungrammatical speech caused by damage to Broca’s area
what is Wrenkie’s aphasia?
producing meaningless speech and are unable to understand other people’s speech
what is a characteristic of Wrenkie’s aphasia?
the inability to match words with meanings
what were Broca and Wrenkie’s findings significant to?
the discovery that language aspects are served by different areas of the brain
describe the upper temporal lobe
contains the auditory cortex and receives signals from the ears
describe the parietal lobe
contains the somatosensory cortex which receives signals from the skin
describe the frontal lobe
receives signals from all senses and is responsible for coordination of all the senses and higher mental processes
what is prosopagnosia?
the inability to recognize faces due to damage of the right/lower temporal lobe
describe double dissociation in neuropsychology
damage to one area of the brain impairs function A but keeps function B intact while damage in another area of the brain impairs function B and keeps function A intact
what does double dissociation enable?
the idea that 2 functions are served by different mechanisms that operate independently from each other
who said 97% of neurons within a small part of the monkey’s temporal lobe responded to pictures of faces but not to objects
Doris Tsao
what supported Tsao’s temporal lobe experiment?
brain imaging to allow one to see which areas of the brain are activated by different cognitions
what is functional magnetic resonance imaging
shows how neural activity causes the blood to bring in more oxygen that binds to hemoglobin to increase its magnetic properties
what are voxels?
small cube-shaped areas of the brain and are units of analysis associated with cognitive activity
what is a task-related MRI
measures the change in brain activity that can be linked to specifically to the task
what is the fusiform face area?
located in the fusiform gyrus on the underside of the temporal lobe
part of the brain damaged in cases of prosopagnosia
what is the para-hippocampal place area?
responds to information regarding spatial layout
what are the 4 steps of determining if structures are apart of a functional network?
- task-related MRI to determine the location associated with a specific task
- measure the resting-state fMRI at the same location and collect a times-series response
- measure the resting-state fMRI at another location
- calculate the correlation between the seed and test location responses
what is a time-series response?
indicates a change over time
what does a high correlation between seed and test locations mean?
the structures are apart of a functional network
what does a low correlation between the seed and test locations mean?
the structures are not apart of the same functional network
does being functionally connected mean the structures directly communicate by neural pathways?
no
functional and structural connectivity are …
not the same thing but can be related
what occurs during the day and what occurs at night?
day: changing in memory networks due to memories accumulating in the day
night: the strengthening of those memories
what is the default mode network?
a network of structures that respond when a person is not involved in specific tasks
who noted that fMRI studies present a decrease in activity in certain areas of the brain when demonstrating a task?
Gordon Shulman
who proposed areas decrease during tasks represents a default mode of brain function
Marcus Raichle
what do people tend to do when the default mode network is active?
mind wandering - a decrease in performance on attention-required tasks
