PSY 223 Intro Cog Exam 1 Detail Flashcards
Cognitive neuroscience:
the neuroscience of cognitive processes
Neuroscience:
study of the structure and function of the nervous system
Cognition:
the mental action of acquiring knowledge and understanding through thought, experience, and the senses
Sensory info can contribute to thoughts
Give rise to neural activity
Neurology:
function and pathology of the nervous system
That brian region is important for that cognitive function
Psychology:
study of the mind and its implications for behavior
What types of cognitive process we might want to examine
Broad relationships between brain and behavior
Localization of function:
each function is localized to a brain region / each brain region has a specific function - one to one mapping
Broad relationships between brain and behavior
Mass action:
each function can’t necessarily be localized to a specific brain region / each brain region isn’t specialized for a particular function - that brain wasn’t specialized all of brain was doing all tasks
Neuronal Signaling
Chemical NT carry signal
Electrical impulses carry signals within a neuron
inputs from other neurons cause excitatory or inhibitory postsynaptic potentials at the dendrites
postsynaptic potentials (PSPs) may “add up” with temporal or spatial summation
post-synaptic potential:
change in potential that a neuron causes downstream
from a single action potential, a neuron might not be able to induce an action potential on its own
If the PSPs add up to increase membrane potential enough, this may cause a neuron’s membrane potential to reach a critical threshold, an action potential is generated
spatial summation examples
neurons in primary visual cortex (V1)
neurons in the superior olive (sound localization in the horizontal plane)
neurons in middle temporal area (MT)
Ways to compare methods:
temporal/spatial summation
Spatial summation:
Simultaneous EPSPs in diff. parts of neuron
add and sum to produce AP
- spatial summation (multiple neurons summing across space)
location of brain region
- how resolved in space is the method, i.e. how specific is the spatial location of this method? - across neurons (for example, neuron vs. broad region of brain)
Temporal summation:
Rapid repeat EPSPs same location (EPSP lasts a while)
add and sum to produce AP
- temporal - when there is a change in brain activity
- how resolved in time is the method, i.e. how specific is the timing of this method? - across time (for example, milliseconds vs. minutes)
EPSPs summate across time from one neuron (temporal summation) or across space from multiple neurons (spatial summation)
single-cell recording:
measure electrical potential/activity/ signal in a single neuron (good spatial resolution, good temporal resolution) - individual neuron
electrocorticography (ECoG):
measure electrical potential/ activity/signal across neurons, recording directly on or in the brain (good spatial resolution, good temporal resolution) - group of neurons so a larger region
electroencephalography (EEG):
measure electrical potential/ activity/signal across neurons from the scalp (poor spatial resolution, good temporal resolution) - not sure where its coming from
magnetoencephalography (MEG):
based on magnetic signal generated from electrical postsynaptic activity, recorded at the scalp (poor spatial resolution, good temporal resolution)
Single-cell activity:
Single-cell activity: recorded in voltage, but it is often reported by the presence of an action potential
“All or none” principle of the action potential: a neuron usually has a characteristic action potential shape
Representations of the body in cortex for M1 and S1
Somatotopy: different parts of M1 / S1 correspond to planning and control of movement / somatosensation in different body parts
- So there are neurons that respond to specific body parts
- Individual neurons have a specific body part
- So the group of neurons are all near each other
Each side of the brain M1 and S1 corresponds to the contralateral side of the body
Not consistent with anatomical size (e.g. more brain tissue devoted to hands than arms)
Not consistent with anatomical order - not from top to bottom or left to right
Primary motor cortex M1
Neurons located nearby each other are more likely to be more active when planning movement of the same body part
Neurons more active when planning movement of the same body part differ with respect to the direction of movement which leads to the most action potentials
An individual neuron in M1 fires the most action potentials during planning of movement of a particular body part AND movement of that body part in a specific direction - start point doesn’t matter just same general direction and not in relation to oneself just direction of movement of a body party
Motivation for neuroimaging
Take advantage of the fact that more active brain regions require more resources - more blood
Indirect measure of neural activity
Whole team of brain regions want to know which is more active
Neuroimaging looking at resources of more blood
Neuroimaging methods measuring blood flow
more active brain regions use more (oxygenated) blood (good spatial resolution, poor temporal resolution)
functional magnetic resonance imaging (fMRI): tracks blood flow based on the magnetic properties of oxygenated vs. deoxygenated blood
Positron emission tomography (PET): Tracks blood flow using a radioactive tracer
Which brain regions are more active
“Subtraction logic”: PET and fMRI
Interested in a task and find a second task that’s very close to first task
Reading interested in but also picks up vision and breathing
Not enough saying flowing blood instead we must subtraction
Lesion studies
Definition:
Electrophysiology and neuroimaging
Definition: “a region in an organ or tissue which has suffered damage through injury or disease”
Damaging brain region and how that imparies cog function
Lesions can identify if a brain region is necessary for a function: if someone is missing brain region A, and they can’t perform function B => brain region A is necessary for function B Lesion studies
Electrophysiology and neuroimaging identify brain regions involved in, or more active during, a function: if brain region A is more active during function B => then it is probably involved in function B
generally good spatial resolution - which area
Transcranial Magnetic Stimulation (TMS):
creates reversible/temporary lesions in humans by creating a magnetic field that influences electrical properties of the brain
Lesion
permanent vs temporary
generally good spatial resolution - which area
permanent
poor temporal resolution - know brain region is important for tasks but not when
temporary
humans: transcranial magnetic stimulation (TMS)
animals: cooling or pharmacological
good temporal resolution
for humans, better control of locations than permanent lesions
Lesion: Analysis approach
Single Dissociation: damaging a single brain region and dissociating particularly properties of that brain region → control normal is good at task and lesion to region 1 says they can’t do task
Double Dissociation: two brain regions are selectively associated with two different tasks
Transduction:
“translation” of external, environmental stimuli into changes in neuronal signaling
Sensation:
“neural processes that correspond most closely to the concept of detection”
Perception:
internal experience of the external world; “identification of features of what is being sensed”
Action:
“isolated acts of motor control…also goals or plans that can be abstracted from isolated movements” - having thought and then making motor movement
Receptive field:
sensory stimulus that provides maximal changes in the membrane potential of a neuron
Vision
Transduction
visual field
receptive fields
Transduction - Each photoreceptor has a receptive field in specific part of visual field
Altogether, all of the photoreceptors’ receptive fields form one’s visual field
Retinal ganglion cell - visual field
receptive fields: ON-center (light in middle) and OFF-center (light off in middle)
optic chiasm:
where some nerve fibers cross from the left and right eyes => each side of the brain has visual information from the contralateral visual hemifield
Organization of V1
cortical magnification
retinotopy
cortical magnification - Visual information presented near the center of the visual field is represented by larger areas of cortex
The majority of neurons in V1 have receptive fields from the center of the visual field (fovea, central portion of the retina)
Thus information central in the visual field is “magnified”
retinotopy spatial relationships preserved from retina - neurons near each other
Neurons in primary visual cortex
Defined by type of receptive field
1) Cells with ON center / OFF surround receptive fields, like ganglion cells (in a particular region of the visual field)
2) simple cell: detects points of light in a single orientation in a particular region of the visual field — like signal line in visual field so diff direction or location
The information leaving the visual cortex divides into 2 main streams of visual information
dorsal: “where” (where in space are these features located?)
ventral: “what” (what do these features comprise?)
dorsal: “where” (where in space are these features located?)
MT
A neuron in MT fires the most action potentials in response to visual movement: A bar of light moving in a specific region of one’s visual field and in a specific direction
Motion processing in region MT thanks to spatial summation
Neurons firing AP in response to light
ventral: “what” (what do these features comprise?)
object recognition:
4 things -
object recognition: Matching representations of organized sensory input to stored representations in memory
– Faces several challenges
1) where does it end? - neurons have lines of light or one for corners but not effective to have neurons only doing one single line similar to grandma so you can recognize here even if she gets a haircut
2) object constancy: can be viewed as a constant object despite change in perspective, size, etc. - so different shapes of blue car can still see that it’s a blue car
3) object composition: many objects consist of the same collection of features
Another example: Different objects, similar sets of features
4) aperture problem: integrating information from early visual regions, where neurons are sensitive to small regions of visual space, into a coherent picture across larger regions of visual space - can put the whole image together to a larger picture
Solution to “where does it end” and object constancy
“What”/ventral pathway and inferior temporal cortex has many solutions to the challenges of object recognition
“Distributed coding”: A response to an object is distributed across increased activity from several neurons — Way we could for individual object is distributed across several neurons
Neurons are sensitive to more complex sets of features (such as stimuli on the right) but no “top level” such as e.g. a neuron only sensitive to one’s grandmother
Increased activity to a set of neurons
Solution to aperture problem
“What”/ventral pathway and inferior temporal cortex has many solutions to the challenges of object recognition
group features together in principled ways
Similarity/Proximity: link alike items together
Continuity/Closure: link items with missing pieces - some parts of cat is missing still link
Expectations/Pre-existing knowledge
Audition: Input signal
Sound
Frequency
Intensity/amplitude
Transduced
Combined
Sound = changes in (oscillatory) air pressure over time
Frequency (oscillations per second): perceived as pitch —– Higher frequency is pitch
Intensity/amplitude: perceived as loudness —- Height of signal then how loud sound is perceived
Transduced inner hair cells of coahela
Information from left ear and right ear is combined to localize where sound is something from and then sent to A1
Low frequencies (below 100 Hz):
A neuron fires an action potential at a particular phase for a certain frequency (e.g. peak), so its timing is in sync with the wave
Volley principle (100-4000 Hz):
a group of neurons (“volley”) encodes the frequency, because no one neuron can fire action potentials quickly enough on its own
Rate at which air pressure oscillate is faster than neurons so they need to act as a group to encode a frequency
Tonotopy (100-20000 Hz):
Tonotopy (100-20000 Hz): sound causes maximum vibration for hair cells at one location on the basilar membrane in the cochlea, which varies in width and height - at extreme low or high frequency
Tonotopy: systemic organization of characteristic frequency within an auditory structure
Sound localization
Horizontal: Relies on the differential timing of information from the left and right ears - superior olive - relies on spatial summation from both ears
Somatosensory receptors
Somatization - all over the body - left side of brain is for right side of body processed in primary somatosensory cortex (S1)
1.mechanoreceptors: receptive to mechanical forces, such as pressure, texture, vibration, stretch
2.thermoreceptors: receptive to heat and cold
3.nociceptors: receptive to sensory processes signaling (risk of) tissue damage, which can trigger pain response
Receptive fields of somatosensory receptors
vary in
1.location of the body part it covers
2.size of the body part it covers
3.the type of stimulus it is sensitive to
4.for frequency-sensitive mechanoreceptors, the optimal frequency of vibration
Controlling for adaptation when measuring (somatosensory) receptor responses
adaptation:
adaptation: “decreased response to a stimulus as a result of recent exposure to it” - neuron can adapt with lost of exposure - so exposed to cold
Cerebellum
Motor coordination
motor sequences requiring precise aim and timing
fine-tuning of movements
posture (“the position in which someone holds their body when standing or sitting”)
Basal ganglia
Regulating motor activity, such as starting and stopping actions
Parkinson’s disease: specific type of damage to the basal ganglia relevant symptom of
Parkinson’s disease: difficulty initiating and maintaining motor movements
Mirror neurons
Fire the most action potentials in response to
1) a specific action or set of actions performed by the self or
2) the same (set of) action(s) as in 1, but performed by another
Some seem to fire more action potentials in response to specific actions performed by another; some respond to a wider range of actions
These actions usually consist of a series of individual movements
action potentials are regenerated at
the nodes of Ranvier
Axon hillock
origin of the action potential
Supplementary motor cortex
most active just before a rapid series of movements
e.g. push, turn, then pull a mechanical key, playing piano or guitar
Premotor cortex
primarily active during preparations for a movement (e.g. grab a cup)
somewhat active during the actual movement
