PSY 223 Intro Cog Exam 1 Flashcards
Which scientific or medical fields were involved in the emergence of cognitive neuroscience?
Neuroscience: study of the structure and function of the nervous system
Neurology: causes and effects of diseases of the nervous system
Psychology: study of the mind and its implications for behavior
Cognitive neuroscience: the neuroscience of cognitive processes
What does it Involve
Behavior: what someone does - external in this course, typically observable and measurable
Mind: element of a person that enables them to be aware of the world and their experiences, to think, and to feel - internal
Linking cognition to the brain
Cognitive Psychology: study of the cognitive processes of the mind and its implications for behavior
What is the term for the primary cell in the brain?
Neuron
Cognition:
the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses
Perceiving motion (basic), remembering a fact, having a conversation(more complex)
Localization of function:
each function is localized to a brain region / each brain region has a specific function
Different brain regions are important for different functions
Mass action:
each function can’t necessarily be localized to a specific brain region / each brain region isn’t specialized for a particular function
Equipotentiality:
extreme form of mass action - all brain regions perform the same functions - not accurate
How is each involved in neuronal communication? synapse, myelin sheath, node of Ranvier, dendrite, soma, axon, neurotransmitter, and Axon hillock
Synapse: site of communication between neurons - neurons close enough to pass chemical signal
Myelin Sheath: insulates the AP around axon so it doesn’t die out and speeds it up
Node of Ranvier: Action potentials are regenerated
Dendrite: receiving processes, i.e. receives input from other neurons
Soma: cell body
Axon: transmitting process, i.e. transmits a signal to other neurons
Neurotransmitter: a signal a neuron sends
Released from synaptic vesicles by presynaptic neuron (axon)
Bind to receptors on postsynaptic neuron (dendrite)
Can be excitatory or inhibitory
Axon hillock: origin of the action potential
What does resting membrane potential refer to?
When the cell is at rest the inside is more negatively charged than the outside - resting membrane potential -70mv
The electrical potential difference across the plasma membrane when the cell is in a non-excited state.
At resting potential concentration of ions is kept constant through Na+/K+ pumps. When the threshold is reached, the Na+ gated channels are opened.
Sodium Potassium Pump: 3 sodium out and 2 potassium in
What are the 4 steps of the action potential? For each step: What is it called? Is the membrane potential rising or falling? Is Na+ moving into the neuron, out of the neuron, or neither? Is K+ moving into the neuron, out of the neuron, or neither?
Depolarization Rising Phase - Na goes in making it positive
Overshoot - highest of AP favoring Na
Repolarization Falling Phase - K flows into cell making it negative back to RMP
Hyperpolarization undershoot - K keeps going in super negative below RMP
Restoration - back to RMP K close
What is the “all-or-none” property of the action potential?
An AP either happens completely, or it does not happen at all
Gyrus and Sulcus
Gyrus: raised surface (mountain) of the cerebrum
Sulcus: dips or folds (valley) between such structures
Folding of the cerebral cortex creates gyri and sulci which separate brain regions and increase the brain’s surface area and cognitive ability
Cerebrum largest part of the brain that starts and manages conscious thoughts; meaning, things that you actively think about or do. Cerebellum is a small part of your brain located at the bottom of this organ near the back of your head.
Comparing methods
Spatial resolution:
Temporal resolution:
Spatial resolution: 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 resolution: how resolved in time is the method, i.e. how specific is the timing of this method? - across time (for example, milliseconds vs. minutes)
Changes in electrical activity in a neuron Integration across signals:
Two main types of postsynaptic potentials
EPSP:
IPSP:
1) EPSP: excitatory postsynaptic potential increase in membrane potential
- Could lead to an action potential if enough EPSPs summate across time from one neuron (temporal summation) or across space from multiple neurons (spatial summation)
- Leads to depolarization of neurons – excites post-syn. Neuron
2) IPSP: inhibitory postsynaptic potential decrease in membrane potential
- Leads to hyperpolarization of neurons – inhibits post-syn. Neuron
Summation:
Temporal summation:
Spatial summation:
Temporal summation:
Rapid repeat EPSPs same location (EPSP lasts a while)
add and sum to produce AP
Spatial summation:
Simultaneous EPSPs in diff. parts of neuron
add and sum to produce AP
Simultaneous EPSP and IPSP in diff. parts of neuron
add and reduce chance of AP
Single-cell recordings
temporal resolution and spatial resolution - good or bad
Analyze activity
Advantages/Disadvantages
Measures brain activity directly based on the electrical properties of communicating neurons so the potential mv (changes in electrical potential)
Have good temporal resolution and spatial resolution
The electrical potential difference between the inside and outside is the total membrane potential (mv)
Analyze activity
- changes in membrane potential
- number and rate of action potentials
Advantages: Most direct and precise way to record neural activity
Disadvantages: Inconvenience for participants - surgery is invasive
EEG Electroencephalography
temporal resolution and spatial resolution - good or bad
Recording electrical activity across cells
Based on electrical signal from postsynaptic activity, recorded at the scalp
Measure brain activity directly based on the electrical properties of communicating neurons
Have poor spatial resolution but good temporal resolution
MEG Magnetoencephalography
temporal resolution and spatial resolution - good or bad
Recording magnetic fields across cells
Based on magnetic signal generated from the electrical postsynaptic activity, recorded at the scalp
Measure brain activity indirectly based on the influence of electricity on magnetic fields
Have poor spatial resolution but good temporal resolution
Intracranial EEG / Electrocorticography (ECoG)
temporal resolution and spatial resolution - good or bad
How does the electrical potential change over time, summed across neurons?
Recording electrical activity across cells
Good temporal resolution and spatial resolution (though not as good as single-cell recordings)
Analyze Activity In EEG and MEG and ECoG
Event-related potential (ERP): average activity across events
Power: oscillations in EEG/MEG activity signal is a combination of oscillations at different frequencies, and power is defined by the strength of those frequencies
- always positive; related to amplitude (height of signal, sometimes taken from the center or mean)
- Greater electrical potential may reflect more synchronized neurons (spatial summation of excitatory postsynaptic potentials, EPSPs)
Oscillations: the rhythmic and/or repetitive electrical activity generated in the brain
Amplitude—distance between the resting position and the maximum displacement of the wave. Frequency—number of waves passing by a specific point per second.
Positron Emission Tomography (PET)
temporal resolution and spatial resolution - good or bad
Tracks blood flowing to more active brain regions using a radioactive tracer
Take “images” based on molecules tied to blood flow, because more active brain regions require more blood
Studies “Where” and “What” pathways/streams
Good spatial resolution
Poor temporal resolution
Functional magnetic resonance imaging (fMRI):
temporal resolution and spatial resolution - good or bad
Detect changes in oxygenated blood flow, which is correlated with changes in neural activity; based on tracking blood flowing to more active brain regions by taking advantage of blood’s magnetic properties. Active brain regions need blood with oxygen (oxygenated blood), oxygenated blood and deoxygenated blood have different magnetic properties.
Take “images” based on molecules tied to blood flow, because more active brain regions require more blood
Good spatial resolution
Poor temporal resolution
Subtraction logic: PET and fMRI
How to determine which brain regions are involved in Cognitive Task A?
Look at activity for Task A because most of the brain needs blood most of the time
Task B: as similar as possible to Task A, except for the cognitive process of interest of Task A
Identify regions that are more during Task A than task B
Permanent Lesions
Lesion:
Human causes of lesions:
Animal causes of lesions:
temporal resolution and spatial resolution - good or bad
Lesion: “a region in an organ or tissue which has suffered damage through injury or disease” → 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
Human causes of lesions: neurosurgery: brain region(s) removed to prevent some other problem (such as epilepsy) OR stroke, neurodegenerative disorders, head injuries, viral infection, tumors
Animal causes of lesions: destroy brain region(s), then have the animal perform a cognitive task
Good spatial resolution
Poor temporal resolution
Reversible animal lesions
temporal resolution and spatial resolution - good or bad
In humans
Animals: more invasive and more common
pharmacological inactivation - block synaptic transmission
cryogenic depression (cooling)
optogenetic imaging - control neuronal function
Good spatial resolution
Good temporal resolution
In humans TMS
Transcranial Magnetic Stimulation (TMS):
temporal resolution and spatial resolution - good or bad
double dissociation vs single dissociation
Creates reversible lesions in humans by creating a magnetic field that influences electrical properties of the brain - not an indirect measure of brain activity because it temporarily damages brain tissue (i.e., creates a lesion)
Creates a magnetic field in a specific area of the brain - magnetic field influences electrical activity, i.e. inhibits of the activity, in a specific area of the brain
Can assess cognitive function while the brain area is temporarily lesioned
Generally good spatial resolution: can have as good spatial resolution as fMRI → where in the brain that stimulation is being applied and what activity was like with and without the lesion
Generally good temporal resolution: can have as good temporal resolution as EEG
Can assess lesions to multiple brain regions in the same participant (double dissociation)
Single dissociation: affecting only one area of function
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
Bottom-up
Top-down
Input signal → Transduction → Bottom-up processing: Integration across inputs → Top-down processing: Using pre-existing knowledge and context
In what type of cell does transduction occur for vision?
Photoreceptors: where transduction takes place for vision translate light into neuronal signal
Rods: receptors for low light (night time) - Low acuity (spatial resolution)
Cones: receptors for high light intensity and different wavelengths (color) Cones and color - High acuity (spatial resolution)
Photoreceptor doesn’t just respond to light anywhere it depends on the location so on or off like photoreceptors respond to light in a particular part of space
A photoreceptor does not respond to light regardless of where the light is located with respect to the visual field
Receptive field:
Intuition:
Receptive field: Sensory stimulus that induces maximal changes in a neuron’s membrane potential
Intuition: Bipolar cell needs input from several photoreceptors across space in the brain (spatial summation)
On center/off center cell:
Off-center In center no light and On-center light in middle
ON-center bipolar cells are depolarized by small spot stimuli positioned in the receptive field center. OFF-center bipolar cells are hyperpolarized by the same stimuli. Both types are repolarized by light stimulation of the peripheral receptive field outside the center
Simple cell
Complex cell
Simple Cell: Detects points of light in a single orientation in a certain part of the visual field relies on spatial summation from several LGN neurons with on-center receptive fields in slightly different visual locations
Complex cell: detect long bar of light in a single orientation in a certain part of the visual field
- relies on spatial summation from several simple cells, so responsive to light in a larger area than simple cells
What is the visual field? Why is there a blindspot in the visual field?
Fovea / central retina: more densely populated with cones
Rods are more towards the periphery
Blind spot: at the optic disk, where the optic nerve fibers leave the eye - no photoreceptors
Visual field: “total area in which objects can be seen in the side (peripheral) vision as you focus your eyes on a central point”
Retina: Order back of eye to front
Pigmented epithelium (back of eye)
Photoreceptors - rods and cones
Bipolar cells
Ganglion cells (light)
Light goes back of eye to photoreceptors
How is information represented from eyes on the left and right side of the body to the left and right side of the brain?
Retinogeniculate Visual Pathway: conveys visuals info from retina to LGN(thalamus) → optic chiasm: where some nerve fibers cross from the left and right eyes => each side of the brain has visual information from the contralateral (opposite) visual hemifield
Where is sensory information first processed in the cortex?
Once leave retina → optic nerve, optic chiasm, LGN, V1 or Primary visual cortex
Primary somatosensory cortex or V1 or primary visual cortex
Retinotopy:
spatial relationships preserved from retina - mapping of visual input from the retina to neurons
Cortical magnification:
Visual information presented near the center of the visual field is represented by larger areas of cortex, i.e. the majority of neurons in V1 have receptive fields from the center of the visual field (fovea). Thus, this central information is “magnified” → The number of neurons in the visual cortex responsible for processing the visual stimulus of a given size varies as a function of the location of the stimulus in the visual field.
Define object recognition:
Matching representations of organized sensory input to stored representations in memory
Involves bottom-up processes (e.g. integrating lower level features) and top-down processes (e.g. knowledge, expectations, context)
“Where” and “What” pathways/streams → The information leaving the visual cortex divides into 2 main streams of visual information
Dorsal: “where” (where in space are these features located?) determining the location of an object
Ventral: “what” (what do these features comprise?) determining the identity of an object
Inferior temporal cortex (IT) and the “what” pathway
- Matching representations of organized sensory input to stored representations in memory
- Involves bottom-up processes (e.g. integrating lower level features) and top-down processes (e.g. knowledge, expectations, context)
What/Ventral: Main challenges of visual object recognition
Where does it end?
Feature Matching – object constancy
Feature Matching – object composition
Aperture Problem
Relative color
1) Where does it end? Object representations may assemble from “primitives”
- Hierarchical processing in visual system
2) Feature Matching – object constancy: Object is viewed as constant, despite changes in visual input
- M in different sizes is still an M
3) Feature Matching – object composition: Many objects are composed of the same collection of features
- R and P (vertical line and left facing curve)
4) Aperture Problem: integrate information from early visual brain regions into a coherent picture across larger regions of visual field
5) Relative color: what color are you seeing with solution V4
What/Ventral: Understand how human visual object recognition can overcome the above problems, with:
1) distributed coding:
Where does it end?
Distributed coding: An object is “coded” not with APs from one neuron, but is distributed across several active neurons.
Population coding: Representation of a stimulus by the pattern of firing of a large number of neurons
Sparse coding: Representation of a stimulus by a pattern of firing of only a small group of neurons, with the majority of neurons remaining silent
What/Ventral: Understand how human visual object recognition can overcome the above problems, with:
2) grouping the features together in principled ways: visual system groups features together in principled ways
feature matching
Similarity/Proximity: link alike items together
1) similarity: visual elements that are similar (e.g. same color) are likely to be grouped together
2) proximity: visual elements that are close together are likely to be part of the same object
Continuity/Closure: link items with missing pieces
3) continuity: edges are grouped together to avoid interruptions
4) closure: missing parts of an object are “filled in”
What/Ventral: Understand how human visual object recognition can overcome the above problems, with:
3) expectations/pre-existing knowledge:
Aperture
Top-down processing
Dorsal/Where: What information is represented in neurons in region MT?
Motion processing in region MT thanks to spatial summation
Neurons firing AP in response to light
Localization of information in different coordinate systems: where/dorsal things are based to oneself and environment:
Egocentric localization
Egocentric localization: representation of space in a body or self-centered coordinate system; representation of space centered around one’s own location
Hemispatial Neglect: reduced awareness of stimuli on one side of space, even though there may be no sensory loss (what they are paying attention to so like only half of side - not a not seeing thing)
- neglect information on one half (hemi) of one’s space
- commonly on the opposite (contralateral) side to the parietal lobe lesion
- only ate food on the right side of her plate
- when looking at her left hand, she thought it was the doctor’s hand
- spoke about weakness on the right side of her body, even though this weakness was much more pronounced on the left side of her body
Localization of information in different coordinate systems: where/dorsal things are based to oneself and environment:
Allocentric localization:
Representation of space in an environment-centered coordinate system; representation of space with respect to the environment
Place cells in the hippocampus: In a given environment, a place cell fires action potentials in a specific but objective place, i.e. independent of how the animal approaches it
Across cells, much of a given environment can be represented
For each of audition, somatosensation (and vision):
Where does transduction of sensory information occur?
Audition: Sound = changes in (oscillatory) air pressure - Transduced occurs in the cochlea (inner ear) - goes from air to fluid. Transduction occurs in the cochlea via the inner hair cells on the basilar membrane swaying back and forth - hair cells moving at oscillation rate so by pitch
Somatosensation: sensory receptors in the peripheral nervous system
Vision: Photoreceptors
For each of audition, somatosensation (and vision):
What are the receptive fields for each of the transducing sensory receptors?
Audition: Hair cells in cochlea
Somatosensation: Receptive field: Sensory stimulus that induces maximal changes in a neuron’s membrane potential correspond to different parts of the body - size and sensitivity vary by, body part, receptor type
Merkel and Meissner and Pacinian
Vision: Retina rods and cones
For each of audition, somatosensation (and vision):
Where is sensory information first processed in the cortex?
Audition: primary auditory cortex (A1)
Somatosensation: primary somatosensory cortex (S1) = postcentral gyrus
Vision: primary visual cortex (V1)
For each of audition, somatosensation (and vision):
What is the organization of information across neurons (both the term and what it means)?
Audition: 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
Somatosensation: Somatotopy: Different parts of S1 correspond to somatosensation in different body parts
Vision: Right eyes to LEFT LGN: visual info from the right half of the visual field of each eye is transmitted to the left side of the brain. Basically, optic nerve fibers from the RIGHT eye carry info from the right visual field to the left LGN→ LEFT BRAIN. Left Eye to RIGHT LGN: opposite of above
For each of audition, somatosensation (and vision):
How is information integrated from both sides of the body to both sides of the brain?
Audition: superior olive (combine ears) - Sound localization in the horizontal plane
Somatosensation: crosses sides at medulla
Vision: opposite side of brain at the optic chiasm
How do we sense/perceive each of the following:
Oscillatory changes in air pressure
Frequency (oscillations per second): perceived as pitch
How do we sense/perceive each of the following:
different frequencies of oscillatory changes in air pressure
High Pitch = High frequency
Base of cochlea
Low Pitch = Low frequency
Apex of cochlea
How do we sense/perceive each of the following:
different amplitudes of oscillatory changes in air pressure
height of signal
Intensity/amplitude: perceived as loudness
What are the 3 properties of inner hair cells that allow for transduction of different sound frequencies?
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
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
What are 3 different types of somatosensory receptors?
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
What are 4 ways the receptive fields of somatosensory mechanoreceptors can vary?
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
Define adaptation (with respect to receptor responses)
important to account for adaptation: “decreased response to a stimulus as a result of recent exposure to it”
Sound localization - combining info across ears is helpful with this
Horizontal: Relies on the differential timing of information from the left and right ears
Vertical: Relies on reflections from the pinna
Top-down auditory processing
More nerves go to the cochlea from the brainstem than from the cochlea to the brainstem
Superior olive:
Pinna:
Superior olive: Sound localization in the horizontal plane
Pinna: Sound localization in the vertical plane
Audition
Sound
Audition – act, sense or power of hearing sound
Sound- series of pressure waves in air (or other medium)
Summary: Transduction in the ear
Different frequencies of bbbbbbbbbbb (pitch) and bbbbbbbbb (amplitude) are encoded based on the properties of the inner hair cells
Sound corresponds to changes in air pressure
Sound is transduced via vibrations in the inner hair cells on the basilar membrane of the cochlea
Different frequencies of sound (pitch) and loudness (amplitude) are encoded based on the properties of the inner hair cells
Define somatotopy (as it relates to motor movements, not somatosensation)
Different parts of M1 correspond to planning and control of movements in different body parts
Like S1, each side of brain corresponds to the contralateral side of the body
Like S1, not consistent with anatomical order or size
However, not the same mapping as S1
Beyond somatotopy, what else informs when a neuron will fire the most action potentials in M1?
Neurons in M1 are active prior to a movement, during motor preparation
Individual neurons in M1 fire the most action potentials during planning of movement of a particular body part AND movement of that body part in a specific direction
Number of AP varies with movement - across neurons diff rate at which they fire AP but each neuron has a different body part with a specific body part
Vector has direction and and magnitude
Translate neuronal activity into a vector:
direction = direction with greatest response rate
magnitude = response rate
Population coding
What 2 types of stimuli cause a mirror neuron to fire the most action potentials?
Exist in motor cortex regions outside of M1, including premotor cortex
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
Hypothesized roles beyond motor movement remain controversial
contribute to motor movements: Cerebellum
Cerebellum: Motor coordination
motor sequences requiring precise aim and timing
fine-tuning of movements
contribute to motor movements: Basal ganglia
Basal ganglia: Regulating motor activity, such as starting and stopping action
contribute to motor movements: 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
contribute to motor movements: Premotor cortex
primarily active during preparations for a movement (e.g. grab a cup)
somewhat active during the actual movement
Summary: Movements in primary motor cortex (M1)
Neurons in a region of M1 will fire the most action potentials when planning the movement of a specific body part
An individual neuron within a region of M1 will fire the most action potentials when planning the movement of a specific body part in a specific direction - each neuron diff direction of movement
Recording from multiple neurons at once, it is possible to predict the planned motor movement of a body part
Ascending BLANK information and descending BLANK information are severed
somatosensory
Motor
