cognitive neuroscience midterm #1

What did Ebbinghaus study with nonsense words?

He measured memory with savings and established the forgetting curve (forgetting happens quickly at first then slows down).

savings = ((initial learning rep - relearning rep)/initial learning rep) * 100

introduction of quantitative measures in psychology.

What is behaviorism?

To predict and control behavior
– No concern for what happens in between
– Rejected the use of mentalistic concepts
(e.g., the mind, imagery, thinking,
consciousness)

What are the methods of behaviorism?

Studied how stimuli in the environment
(input) influence the organism's response
(output)

Animal research:
- Classical conditioning
- Instrumental learning

What was the cognitive revolution?

a major shift in psychology during the 1950s–1970s, moving the focus away from behaviorism (which studied only observable behaviors) and toward understanding /making inferences about internal mental processes—like thinking, memory, problem-solving, and language.

ex. chomsky challenging human language/the misbehavior of organisms/human mind as a computer

How did behaviorism differ from the cognitive revolution?

behaviorism: observable behavior, mind as black box, stimulus response/conditioning experiments, learning based on reinforcement and punishments

cognitive revolution: focused on mental processes, mind as computer, lab experiments/models/RT/error analysis, based on understanding of mental rep of info

Who criticized the methods of behaviorism and why?

chomsky - language is too complex to be explained by classical conditioning alone because children make novel sentence and similar grammatical errors

the misbehavior of organisms - challenged idea that animal behavior could be shaped by operant conditioning because trained animals reverted back to instinctive behavior/stop doing trained behaviors

Describe what is meant by the information processing approach.

views the mind as a system that:

• Receives input (information), Processes it, Produces an output (behavior or response)

• It involves encoding, storing, and retrieving information

1. Input - Information from the environment (e.g., what you see or hear)

2. Attention - Focusing on certain information while filtering out others

3. Perception - Interpreting sensory input into meaningful patterns

4. Memory - Encoding: Getting information into the system, Storage: Keeping it over time, Retrieval: Bringing it back when needed, Decision-Making: Evaluating information and choosing a response

5. Output - The behavioral response (e.g., speaking, moving)

What does cognitive psychology and neuroscience contribute to each other?

cognitive psychology contributes: mental processes(e.g., memory, attention, language, thinking), experiments, models, behavior analysis, reaction times THEORIES AND MODELS FOR TESTING

neuroscience contributes: Brain structure and function (neurons, brain regions, neurotransmitters), Brain scans (fMRI, EEG), lesions, neural recordings BIO EVIDENCE FOR THEORIES

the neuron

Dendrite: Receive
signals from other
neurons
• Cell Body:
Organelles to
keep neuron alive
• Axon: Send
signals to other
neurons
• Synapse: Space
between neurons

action potential 1. Resting State (–70 mV)

• The neuron is polarized.

• Inside of the cell is more negative than outside.

• Maintained by the sodium-potassium pump:

  • Pumps 3 Na⁺ out, 2 K⁺ in, using ATP.

action potential 2. Stimulus Received

• A stimulus (e.g., neurotransmitter binding) causes some Na⁺ channels to open.

• Na⁺ (sodium) begins to enter the neuron.

• If enough Na⁺ enters and the membrane potential reaches the threshold (about –55 mV)

action potential 3. Depolarization (Rising Phase)

• Many voltage-gated Na⁺ channels open.

• Na⁺ rushes in, making the inside more positive.

• The membrane potential spikes up to about +30 to +40 mV.

action potential 4. Repolarization (Falling Phase)

• Na⁺ channels close, stopping sodium inflow.

• K⁺ (potassium) channels open, and K⁺ rushes out.

• The neuron becomes negative again as K⁺ leaves.

action potential 5. Hyperpolarization (Undershoot)

• K⁺ channels stay open too long, so the membrane becomes more negative than resting potential (e.g., –80 mV).

• This is called hyperpolarization or the refractory period.

action potential 6. Return to Resting Potential

• K⁺ channels close.

• Sodium-potassium pump restores balance.

• Neuron returns to –70 mV and is ready for the next signal.

How do neurons communicate through the synapse? Action Potential Arrives 1

An action potential travels down the axon of the presynaptic neuron.

• When it reaches the axon terminal, it triggers the process of neurotransmitter release.

How do neurons communicate through the synapse? Calcium Channels Open 2

The depolarization causes voltage-gated Ca²⁺ (calcium) channels to open.

• Ca²⁺ rushes into the axon terminal.

How do neurons communicate through the synapse? Neurotransmitter Release 3

The influx of calcium causes synaptic vesicles (tiny sacs) to fuse with the presynaptic membrane.

• These vesicles release neurotransmitters into the synaptic cleft by exocytosis.

How do neurons communicate through the synapse? Neurotransmitters Cross the Synaptic Cleft 4

Neurotransmitters (like dopamine, serotonin, acetylcholine, etc.) diffuse across the gap.

How do neurons communicate through the synapse? Binding to Receptors 5

Neurotransmitters bind to specific receptors on the postsynaptic membrane.

• This causes ion channels in the postsynaptic neuron to open or close.

How do neurons communicate through the synapse? Postsynaptic Response 6

Depending on the type of neurotransmitter and receptor:

• Excitatory signals (e.g., glutamate) → make the neuron more likely to fire (depolarization)

• Inhibitory signals (e.g., GABA) → make the neuron less likely to fire (hyperpolarization)

If enough excitatory input reaches threshold, a new action potential is triggered in the postsynaptic neuron.

How do neurons communicate through the synapse? Neurotransmitter Removal 7

To stop the signal, neurotransmitters must be cleared from the synapse. This happens by:

• Reuptake: Taken back into the presynaptic neuron (e.g., serotonin reuptake)

• Enzymatic breakdown: Broken down by enzymes (e.g., acetylcholinesterase)

• Diffusion: Drift away from the synapse

anatomical terminology

pre-central gyrus

located in front of central sulcus, containing primary motor cortex and controlling voluntary movement

central sulcus

divides the frontal and parietal lobe, separating Precentral gyrus (motor cortex) and Postcentral gyrus (somatosensory cortex)

post-central gyrus

Located posterior (behind) the central sulcus

Function: Primary Somatosensory Cortex

• Processes touch, pressure, temperature, pain

parieto-occipital sulcus

• Divides the parietal lobe from the occipital lobe

• Visible mostly on the medial (inner) surface of the brain

lateral sulcus (sylvain fissure)

• Divides: the temporal lobe from the frontal and parietal lobes

• One of the deepest and most prominent sulci

calcarine sulcus

• Found in the occipital lobe on the medial surface

• Contains the primary visual cortex

superior temporal gyrus

• Located just below the lateral sulcus

• Function: involved in auditory processing and language comprehension (includes Wernicke’s area in the left hemisphere)

longitudinal fissure

Deep groove that separates the left and right hemispheres of the brain

frontal lobe

• Voluntary movement (motor cortex)

• Planning and decision-making

• Problem-solving

• Speech production (Broca’s area, usually left hemisphere)

• Emotional regulation and personality

• Working memory and attention

occipital lobe

• Location: Back of the brain

• Primary Functions:

  • Visual processing (primary visual cortex)

  • Interpreting color, shape, motion

  • Visual recognition and spatial processing

temporal lobe

• Location: Below the lateral sulcus, sides of the brain near the ears

• Primary Functions:

  • Auditory processing (hearing)

  • Language comprehension (Wernicke’s area, usually left hemisphere)

  • Memory formation (especially the hippocampus within this lobe)

  • Processing emotions and facial recognition

parietal lobe

• Processing sensory information (touch, temperature, pain)

• Spatial awareness and body position (proprioception)

• Navigation and coordination

• Understanding language and mathematics

limbic system

• Located deep inside the brain, including structures like the hippocampus and amygdala.

• Involved in emotion, memory, motivation, and behavior.

corpus callosum

• Connects the left and right hemispheres of the brain

• Allows communication and information transfer between hemispheres

• Enables coordinated, integrated brain function

basal ganglia

• Movement regulation: initiation and control of voluntary movements

• Involved in habit formation and procedural learning

• Plays a role in reward processing and motivation

• Dysfunction linked to disorders like Parkinson’s and Huntington’s disease

hippocampus

• Crucial for forming new explicit (declarative) memories

• Involved in spatial navigation and memory of locations

• Plays a role in learning

• Damage can cause anterograde amnesia (inability to form new memories)

amygdala

• Processes emotions, especially fear and aggression

• Plays a role in emotional memory formation (e.g., memories linked to strong feelings)

• Involved in threat detection and emotional learning

thalamus

• Acts as the brain’s relay station for sensory information (except smell)

• Processes and transmits sensory and motor signals to the cerebral cortex

• Involved in regulating consciousness, sleep, and alertness

hypothalamus

• Regulates homeostasis (body temperature, hunger, thirst)

• Controls the endocrine system via the pituitary gland

• Involved in sleep-wake cycles, emotions, and sexual behavior

cerebellum

• Coordinates balance, posture, and fine motor control

• Involved in motor learning and timing of movements

• Also linked to some cognitive functions like attention and language processing

Describe the relationship between brain regions (e.g. Sylvian Fissure and Central Sulcus)
in anatomical terms

• Anterior (rostral): toward the front

• Posterior (caudal): toward the back

• Superior (dorsal): toward the top

• Inferior (ventral): toward the bottom

• Medial: toward the midline

• Lateral: away from the midline (toward the sides)

What did phrenology contribute to cognitive neuroscience?

Localization of Function

Phrenology introduced the idea that brain areas are associated with complex behaviors and psychological functions — mapping brain regions to functions

Modern Approaches:

– Try to localize brain areas associated with
cognitive processes that contribute to behavior
– Need cognitive theories that specify the
processes that underlie behaviors of interest
– Interpretation of functional imaging results is often
only as good as the theories that guided the
research

lesion

• Observe or test how injuring a brain
  area influences behavior then infer the
  function of that area

• only on human victims of injury so it lacks anatomical precision

• on animals lesions can be induced and anatomically precise

• Poor spatial and temporal resolution

Disadvantages: 

Heterogeneity:
– Lesion site, symptoms, subject
characteristics
• Compensatory strategies and brain
reorganization
• Downstream effects

pharmacological

Observe or test how pharmacological agents
influence behavior then infer the function of
that neurotransmitter system

• can be observed in humans with chronic drug use/experimental administration/not precise

• drugs for animals can be administered to specific brain region/precise
  

Pharmacological agents can alter
neurotransmitter functioning

• Agonist: Bind to and activate receptors

• Antagonists: Bind to and inactivate receptors

• Poor spatial and temporal resolution

stimulation

Stimulate a brain area to alter behavior
then infer the function of that area

• Positive response: Stimulation causes
  behavior (e.g. stimulating primary motor cortex invokes movement)/Negative response: Stimulation inhibits
  behavior

• (humans) electrodes are places on the cortex before epilepsy surgery or induced from outside of the head to identify limited regions responsible for function/(animals) electrodes are placed onto cortex and used to stimulate or disrupt function 

• led to creation of homunculus (somatosensory/motor cortex layout)

(TMS causes electrical
current in underlying brain tissue
• Repetitive TMS can improve or impair
performance on a task
– Weak current: Positive response
– Strong current: Negative response)

• Poor spatial resolution

• Only affects superficial brain regions

• Risk for seizure (rare)

optogenetics

Inserting light-sensitive proteins into neurons (via genes), then using light to activate or silence specific cells with high precision.

Genes for photosensitive ion channels
from algea Implanted into neurons via virus. Laser light then activates or inactivates
neurons

• Invasive; not currently possible in humans.

• Requires genetic modification and implanting optical fibers.

• Mainly used in animal research, so translation to humans is complex.

single-cell recording

Measures correlation between stimulus/response events and electrical activity in neurons
• Can tell us about how neurons in
different brain regions process
information
• Good spatial and temporal resolution

(humans) electrodes placed on cortex pre epilepsy surgery (animals) intra(recording ap in cell)/extracellular(records electrical activity related to AP outside the cell)

Disadvantages: 

• Limited regions recorded in humans

• Invasive and therefore mostly done in
  animals

• Limited to large neurons and not an
  entire network

EEG

The brain’s electrical activity generates electrical field “potentials” measured on the scalp’s surface.
• EEG measures changes in electrical potentials over time through electrical activity on the scalp (best for recording neurons oriented
perpendicular to the scalp)

• Poor spatial resolution — hard to tell where activity is coming from.

• Only detects activity near the surface of the brain (cortex).

• Prone to noise (e.g. muscle movement, blinking).

MEG

measures orthogonal magnetic activity
on the scalp (best for recording neurons oriented parallel to the scalp (in sulci))

• Very expensive and rare.

• Still limited in detecting deep brain activity.

• Requires magnetically shielded rooms.

• poor spatial resolution(sulcal activity)

PET

Measures blood flow using
radio-labeled compounds

• Person given radioactive
  tracer in blood

• Blood travels to active
  brain region

• Tracer decays sending
  off a signal that is
  detected by the machine

Disadvantages:

• Do not directly measure neural activity
  – Poor temporal resolution
  – Safety issues
  – Expensive

fMRI

Measures changes in oxygenated
blood because neural activity causes increase in blood flow

• Increased neural
  activity causes an
  increased demand for
  oxygen

• Magnetic properties
  of oxygenated blood
  is detected by the
  machine

Disadvantages:

• Do not directly measure neural activity
  – Poor temporal resolution
  – Expensive

optical imaging

Brain tissue transmits or reflects light
differently when active

Humans:

• Based on underlying electrical activity
  – Extracranial: Event-related optical signals
  (EROS) reflection measured from outside the head
  – Good temporal but poor spatial resolution

Animals:

• Based on level of oxygenated vs.
  deoxygenated blood
  – Intracranial: Reflection measured directly from the cortical surface
  – Good spatial but poor temporal resolution

Disadvantages:
– Does not directly measure neural activity
– Poor temporal resolution
– Invasive and therefore mostly done in
animals
– Poor signal to noise resolution
– Only records superficial brain regions

Define single and double dissociations? What inferences/interpretations can be better
made from double dissociations as compared to single dissociations?

Single dissociation:
– Lesion to one area of the brain and a
problem in one function while not affecting
other functions

Function A is impaired, but Function B is intact in one patient or condition.

• The difference in performance could just mean Task A is harder than Task B, not that they're neurologically separate.

• suggestive, but not definitive.

Double dissociation:
– Lesions in different brain areas causing
problems with different functions

• Can tell us that a specific brain area is
  important for a specific function

• stronger evidence for functional independence

• Strongly supports modularity — different parts of the brain doing different jobs

How is transcranial magnetic stimulation (TMS) like the lesion approach in some
respects but not others?

• TMS is like a “virtual lesion” — it allows researchers to temporarily and safely disrupt brain function in a controlled way.

• Lesion studies observe long-term consequences of real brain damage, often in clinical populations.

• Therefore:

  • TMS is experimental, precise, and reversible.

  • Lesions are observational, often messy, but reflect real-world dysfunction.

Explain the relationship between neuronal activity and scalp recorded EEG

• EEG measures electrical activity generated by large populations of neurons.

• Specifically, it detects summed postsynaptic potentials (not action potentials) from pyramidal neurons in the cerebral cortex.

• These neurons are aligned perpendicularly to the scalp, and when many fire synchronously, they generate a dipole (a separation of charge) strong enough to be picked up at the scalp.

What are the determinants of whether EEG recorded at the scalp leads to a positive vs.
negative voltage change?

• Determined by the orientation of the dipole and the location of the electrode relative to the source.

• In EEG, positive or negative doesn't directly map onto neural excitation or inhibition — it depends on:

  • Whether current is flowing toward or away from the scalp surface.

  • The geometry of the cortical fold (e.g., whether the source is in a sulcus or gyrus).

• So, voltage polarity reflects direction of current flow, not necessarily the type of neural activity.

What is the relationship between EEG and ERP?

• ERP (Event-Related Potential) is a special type of EEG analysis.

• ERP = the brain's electrical response to a specific stimulus or event, extracted by averaging EEG signals across many trials.

• EEG = raw, continuous brain activity.

• ERP = time-locked, averaged response to specific events within the EEG.

What are the two primary pieces of information used to label ERP components?

• Polarity

  • P = positive deflection

  • N = negative deflection

• Latency (Timing)

  • Given in milliseconds (ms) after the stimulus OR as an order number.

  • Examples:

    • P300: positive peak at ~300 ms

    • N170: negative peak at ~170 ms

    • N1, P2: indicate first, second components

How are the magnetic fields measured by MEG related to the electrical dipoles measured
by EEG?

• MEG and EEG both detect neural activity from electrical dipoles generated by cortical neurons.

• EEG measures the voltage (electric field) created by the dipoles.

• MEG measures the magnetic fields that are perpendicular to those electrical currents (via the right-hand rule).

• MEG is most sensitive to tangential dipoles (in sulci), while EEG detects both radial and tangential sources.

27) How is brain activity measured with PET?

• PET measures metabolic activity using a radioactive tracer (usually attached to glucose or a neurotransmitter analog).

• After injection, the tracer accumulates in active brain regions.

• As the tracer decays, it emits positrons, which collide with electrons, producing gamma rays.

• A PET scanner detects these gamma rays and maps regions of high metabolism (indicating higher activity).

28) How is brain activity measured with fMRI?

• fMRI tracks brain activity using the BOLD signal (Blood Oxygenation Level Dependent).

• Active brain areas consume more oxygen; in response, the body overcompensates, increasing oxygen-rich blood to that region.

• Oxygenated and deoxygenated blood have different magnetic properties, which affect the MR signal.

• fMRI indirectly measures activity by detecting these blood flow changes.

Explain the basics of MRI physics including static field, gradient field, pulse sequence, and receiver coil

Component	Description

Static Magnetic Field (B₀)

A strong, constant magnetic field aligns hydrogen protons (usually 1.5T or 3T strength).

Gradient Fields

Small magnetic fields applied in different directions to localize signals in 3D space. Used to encode position of signals (x, y, z).

Pulse Sequence (RF Pulse)

A radiofrequency pulse knocks hydrogen protons out of alignment. As they relax back, they emit energy. Different tissues relax at different rates.

Receiver Coil

Detects the energy released as protons return to alignment. This signal is used to reconstruct the image

What is the physical change within the brain that is detected by Diffusion Tensor Imaging
(DTI), and what structural characteristic of the brain is DTI used to estimate?

• DTI measures the diffusion of water molecules in brain tissue.

• In white matter, water diffuses along axon fibers, not across them.

• DTI uses this anisotropic diffusion to estimate:

  • White matter tract integrity

  • Direction and pathways of fiber tracts (called tractography)

• It helps map structural connectivity between brain regions.

What are some strengths and weaknesses of EEG, MEG, PET, and fMRI in terms of their
spatial resolution, temporal resolution, and suitability for and potential risk to normal
human subjects?

Method	Spatial Resolution	Temporal Resolution	Risk/Suitability

EEG

Low (cm range)

High (ms)

Safe, non-invasive, suitable for children

MEG

Medium–High (mm-cm)

High (ms)

Safe, but expensive and sensitive to magnetic interference

PET

Low (cm)

Very Low (minutes)

Invasive (radioactive tracer), not ideal for healthy participants or children

fMRI

High (mm)

Low (~2–6 sec)

Non-invasive, safe (no radiation), widely used in humans

Consider an fMRI or PET study showing that activity in some brain region, X, is
associated with some behavior. Can we conclude that region X necessarily controls that
behavior? Why or why not?

No, we cannot conclude causation from fMRI or PET alone.

• fMRI/PET are correlational — they show association, not control.

• Region X might be involved, but not essential.

• Activity could be due to:

  • Upstream or downstream processing

  • Co-activation with other regions

  • General cognitive effort, not task-specific processes

(To establish causation, you need intervention-based methods like lesion studies, TMS, optogenetics (in animals))

What is meta-analysis and what are the advantages over any single study?

• A statistical method that combines results from multiple independent studies on the same topic.

• Looks for consistent patterns across studies, increasing reliability.

Advantages:

• Increased statistical power (more data = stronger conclusions)

• Identifies robust effects across samples, tasks, or populations

• Reduces publication bias or chance findings from individual studies

• Helps detect moderators (e.g., age, method differences)

Define, compare, and contrast sensation and perception.

Term	Definition	Key Distinction

Sensation

The raw input from sensory organs (e.g., light hitting the retina)

It’s about detecting stimuli

Perception

The interpretation of sensory information (e.g., recognizing a face)

It’s about making meaning from sensation

Describe the vision pathway from the eye to the brain.

• Light enters the eye → focused by the cornea and lens

• Hits the retina, activating photoreceptors (rods and cones)

• Signal goes to bipolar cells, then ganglion cells

• Ganglion cell axons form the optic nerve

• At the optic chiasm, some fibers cross hemispheres

• Travels via optic tract to the lateral geniculate nucleus (LGN) in the thalamus

• Projects to primary visual cortex (V1) via optic radiations

• Information continues along dorsal ("where") and ventral ("what") pathways

What is the difference between rods and cones?

Feature	Rods	Cones

Light Sensitivity

Very sensitive (low light)

Less sensitive (need bright light)

Color

No color detection

Detect color (RGB)

Location

Periphery of retina

Concentrated in fovea

Visual Role

Night vision, motion

Daylight, detail, color

37) What is the difference between the magnocellular and parvocellular systems?

System	Magnocellular ("M")	Parvocellular ("P")

Input

Rods

Cones

Sensitivity

Motion, flicker, luminance

Color, fine detail

Speed

Fast

Slow

Pathway

Dorsal stream (Where/How)

Ventral stream (What)

38) Explain the principle of retinotopic (or topographic) mapping in the visual cortex

• Retinotopic mapping means that adjacent areas in the visual field are processed by adjacent neurons in V1.

• Preserves the spatial layout of the visual scene.

• Like a "map" of the retina on the brain's surface.

Explain the principle of cortical magnification as it applies to differences in the V1
representation of foveal vs. peripheral stimuli.

• Fovea (central vision) gets disproportionately large representation in V1.

• This is called cortical magnification — small central area takes up much more cortex than larger peripheral areas.

• Explains why foveal vision is so detailed.

Describe how neurons in different V1 hyper columns vary in the information to which
they are responsive. What are neurons in the blobs sensitive to?

• V1 hypercolumns contain:

  • Orientation columns: respond to specific edge orientations

  • Ocular dominance columns: prefer input from one eye

  • Blobs: sensitive to color and brightness (parvocellular input)

Each hypercolumn represents a full set of features for one small area of the visual field.

What is a receptive field?

• A receptive field is the specific area of the visual field where a stimulus must appear to affect the firing of a neuron.

• Receptive fields are small in early areas (like V1) and get larger in higher areas (like IT).

What is the difference between the dorsal and ventral visual pathways?

Pathway	Dorsal ("Where/How")	Ventral ("What")

Function

Spatial location, motion, guiding action

Object recognition, identity

Brain Areas

Parietal lobe

Temporal lobe

Input

Magnocellular

Parvo + magno

What are the properties of visual perception and how do they correlate with physical
reality?

Brightness

Intensity of light

Color

Wavelength of light

Shape

Edges, contours

Depth

Binocular disparity, motion, cues

Motion

Changes in position over time

How do visual areas V1, MT, and IT differ in the types of stimuli to which they are most
sensitive?

V1 (Primary Visual Cortex)

Edges, orientation, basic features

MT/V5 (Middle Temporal)

Motion, direction, speed

IT (Inferotemporal Cortex)

Complex objects, faces, shapes, categories

45) Where in the brain is category specific information stored?

• Stored in high-level visual cortex, particularly ventral temporal lobe:

  • Fusiform face area (FFA): faces

  • Parahippocampal place area (PPA): places/scenes

  • Extrastriate body area (EBA): body parts

• These areas show category-selective activation.

46) Describe the fMRI and ERP results related to face perception and perceptual expertise.

fMRI	Strong FFA activation for faces, and sometimes objects of expertise (e.g. birds for bird experts)

ERP	N170 component larger for faces than objects; appears ~170 ms post-stimulus

47) Compare and contrast the patterns of spared and impaired abilities shown in patients with apperceptive agnosia, associative agnosia, and prosopagnosia

Apperceptive agnosia

Cannot form a stable percept; poor copying or matching

Basic vision, light/dark, acuity

Associative agnosia

Can perceive objects, but can’t identify them

Can copy images, describe shapes

Prosopagnosia

Can’t recognize faces

Can recognize objects, sometimes voice or gait

48) Describe the single-cell recording results related to object recognition.

• In monkeys, neurons in inferotemporal cortex (IT) respond selectively to:

  • Complex shapes, faces, or specific objects

  • Some neurons even show invariance (e.g., respond to a face despite size, angle, position)

• Shows hierarchical processing:

  • Early areas (V1): simple features

  • Higher areas (IT): complex, meaningful objects