Psych 120A Midterm Study Guide: Key Terms & Definitions

scientific study of knowledge and thought

What is cognitive psychology?

examples of cognitive psychology

Memories, Problem Solving, Decision Making, Attention, Reasoning

cognitive psychology

How is our knowledge of the world represented?

What mental processes are involved in acquiring,accessing, and using this knowledge?

How can we measure behavior to make inferences about mental representations and processes?

representation

A set of objects that stand for another set of objects by virtue of having the same causal relational structure.

External Objects

we believe are out there in the world, but we don't have access to it

Internal Representation

bouncing off our retina, and we create a representation and make assumptions of that

Processes

operations that transform one representation into another

Mental representations:

1) are formed in the mind

2) are activated by objects/events in world

3) make it possible to think about objects/events in their absence

Mental processes

operations performed on mental representations

Cognitive offloading

We offload information to the cloud and our devices

We allow ourselves not to remember things we dont need to remember

Dendrites

detect incoming signals

The cell body

contains the nucleus and cellular machinery

Axons

transmits signals to other neurons

axon terminal

The endpoint of a neuron where neurotransmitters are stored

myelin sheath

A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.

Neural Impulses

Neurons process information by electric impulses that travel down the axon

Action Potential

Sends an electrical impulse known as an

86 million

How many neurons are in the human brain?

Synaptic Neurotransmission

When the action potential reaches the axon terminal, it causes the release of neurotransmitters into the synapse

100,000,000,000,000

To process information neurons must communicate with one another. How many total connections are there in the human brain?

360 MPH (faster than the fastest car)

Neurons communicate by sending electrical signal. How fast can these signals travel?

Gray matter of the brain

contain the cell bodies of the neurons

White matter of the brain

contains the axons. Axons are covered with myelin, which insulates and increases the speed of conduction

Diffusion Tensor Imaging (DTI)

an MRI-Based technique to image white matter pathways

Medial View

Lateral View

Top-Down View

electric impulses that travel down the axon

How do neurons process information?

Synapse

is the gap between two neurons

The Connectome of the Human Brain

Map out how each area of the brain transmits information to other areas

Synaptic Neurotransmission

communication bw neurons occurs at synapse, neurotransmitters released from axon of presynaptic neuron and picked up by receptors in dendrites or soma of postsynaptic neuron which have receptors that bind specific neurotransmitters, binding triggers electrochemical change in postsynaptic neuron

Brain Tissue Issue Types

Gray and White Matter

Axons are covered with Myelin

Why is the white matter white?

Conduction

The speed at which these electrical signals travel along axons

to track how one area of the brain is connected to one another

How can we Diffusion Tensor Imaging (DTI)?

Anterior

front of the brain

Posterior

back of the brain

Superior

top of the brain

Inferior

bottom of the brain

Left

left hemisphere of the brain

Right

right hemisphere of the brain

Dorsal

superior

Ventral

inferior

Rostral

toward the nose

Caudal

toward the tail or inferior end

frontal lobe

central fissure

Parietal Lobe

Lateral fissure

temporal lobe

occupital lobe

Cerebellum

cebrebral cortex

auditory context

strip of cortex in the temporal lobe that is responsible for processing auditory information

visual cortex

The visual processing areas of cortex in the occipital and temporal lobes.

primary sensory cortex

regions of the cerebral cortex that initially process information from the senses

association cortices

complex processing that goes on between the arrival of input in the primary sensory cortices and the generation of behavior.

Touch cortex

somatosensory cortex

somatosensory cortex

area at the front of the parietal lobes that registers and processes body touch and movement sensations (arms, legs, fingers)

motor cortex

an area at the rear of the frontal lobes that controls voluntary movements (motion of legs, arms, fingers)

Homumculus

a depiction of what we would look like if each of our parts grew in proportion to how much we sense with them

Integrate Isolate model

involved in integration, adding regions connected to brain areas responsible for coordinating complex movements

Corpus Callosum

Major white matter pathway that connects the two hemispheres of the brain

split brain syndrome

A condition in which an individual's corpus callosum is severed such that the two hemispheres of the brain cannot communicate with each other.

left visual field

right hemisphere

right visual field

left hemisphere

left hemisphere

language, speech

right hemisphere

controls the left side of the body; creative, intuitive, spacial

contralateral organization of vision

Information from left visual field is processed in the right hemisphere, and vice versa

Split Brain Experiment

When a person with a split brain is presented with the picture of a ring on the right and a key on the left side of a screen, she can verbalize ring but not key because the left hemisphere "sees" the ring and language is usually located in the left hemisphere. She would be able to choose a key with her left hand from a set of objects behind a screen. She would not, however, be able to pick out a ring with her left hand because what the left hemisphere "sees" is not communicated to the left side of her body.

Studying split brain patients

History of Functional Brain Mapping

Was right about that certain areas of the brain do certain things, however, was off on the functions

The First "Brain Imaging Experiment"

Angelo Mosso

When the brain is engaged there is more blood flow, the patient would tip down due to redistribution of blood in his system

So it was like a seesaw that was evenly distributed allowing the individual to stay straight. Once they solved math problems or reading, they would tilt downwards representing an increase of blood flow to the brain.

The Brains Blood Supply

Positron Emission Tomography (PET)

a method of brain imaging that assesses metabolic activity by using a radioactive substance injected into the bloodstream

Neural activity → increased metabolic demand → local increase in blood flow the active region

it’s describing a physiological response called neurovascular coupling. Here's how it unfoldsNeurovascular coupling refers to the relationship between neural activity and blood flow in the brain, where increased brain activation leads to heightened blood supply to those areas, supporting their metabolic needs.

Single word processing with PET

cognitive subtraction

a type of experimental design in functional imaging in which activity in a control task is subtracted from activity in an experimental task

Pros of PET Scan

1. Decent spatial resolution (the quality)

2. Can be used for diagnostic purposes

3. Can also measure neurotransmitter metabolism (e.g., dopamine)

4. Very quiet (good for auditory experiments

Cons of PET

1. invasive

(radioactive injection)

2. Very expensive ($3-5k per scan)

3. Poor temporal resolution (cannot detect the neural response to discrete cognitive effects) (change over tiime is slow and not good at measuring quick changes in brain activity. )

Magnetic Resonance Imaging (MRI)

brain-imaging method using radio waves and magnetic fields of the body to produce detailed images of the brain

1. Strong Magnetic Field

   • You lie inside a large magnet. This magnetic field causes hydrogen protons (found abundantly in water and fat) in your body to align like tiny compass needles.

2. Radiofrequency Pulse

   • A burst of radio waves is sent into your body, knocking those aligned protons out of position.

3. Relaxation & Signal Emission

   • When the pulse stops, the protons relax back to their original alignment. As they do, they emit radio signals.

4. Signal Detection & Image Formation

• These signals are picked up by receiver coils and processed by a computer to create detailed cross-sectional images of your body.

MRI physics

Atoms with an odd number of protons and/or neutrons are capable of acting as magnets

-A strong magnetic field causes hydrogen atoms to align in the same orientation.

-When a radio frequency wave is passed through the head, atomic nuclei emit electromagnetic energy.

-The MRI scanner is tuned to detect radiation emitted from the hydrogen molecules.

-Computer reconstructs image.

MRI

studies brain anatomy

Functional MRI (fMRI)

studies brain function

Blood Oxygenation Level Dependent (BOLD) signal indirect measure of neural activity

neural activity --> blood oxygen --> FMRI signal

1. Blood Oxygen Level Dependent (BOLD) Signal

   • When neurons in a brain region become active, they consume more oxygen.

   • The body responds by increasing blood flow to that area.

   • fMRI detects these changes in blood oxygenation, which indirectly reflects neural activity.

2. Magnetic Field & Signal Detection

   • Like a regular MRI, fMRI uses a powerful magnet to align hydrogen atoms.

   • As blood oxygen levels shift, the magnetic properties of hemoglobin change—this alters the signal picked up by the scanner.

3. Task-Based or Resting-State Scans

• You might be asked to perform a task (e.g., tap your fingers, recall a word) during the scan.

• The fMRI maps which brain regions light up during that activity. And is used to visualize brain activity through changes in blood flow.

BOLD

Blood Oxygenation Level Dependent

Structural MRI scans

are useful for clinical imaging (diagnosis)

MRI vs. fMRI

Hemodynamic response function (HRF)

changes in the BOLD signal over time

FMRI setup

Contrasting BOLD activation across conditions

blocked design

experimental units or subjects are placed into groups based on certain properties identified for control purposes. Then blocks are randomly assigned all treatments within each block. Comparisons are drawn within blocks.

event-related design

stimuli from two or more conditions are presented randomly or interleaved

Advantages of Event Related Design

Characterize individual trails after-the-fact, based on the subject's behavioral response

Compare incorrect and correct trials

With FMRI, every two seconds there is a measure level

Group-level statistical analysis

crucial for inference that effects generalize across the population

functional segregation

Organization into different areas, each of which performs a different function; for example, in sensory systems, different areas of secondary and association cortex analyze different aspects of the same sensory stimulus.

functional integration

the way in which different regions communicate with each other

fMRI pros

1. Good spatial resolution (1-3mm3) allows precise localization of brain activation

2. Non-invasive (no known harms to subjects)

3. scanners widely available at medical centers and research universities.

fMRI cons

1. Although temporal resolution (1-4 sec) is far better than PET scans, still much slower than measuring actual neural activity

2. Expensive (~ $600/hour)

3. Scanner noise is very loud

4. only measures blood flow, it does NOT provide precise info about the timing of neural activity.

Electroencephalogram (EEG)

an record electrical activity from large populations of simultaneously active neurons at the scalp with millisecond resolution.

is a direct measure of neural activity.

Arousal states of the brain: characteristic waveform patterns

ERP (event-related potential)

Characterizing electrical activity changes

evoked during specific cognitive events

a measure of electrical activity from a subpopulation of neurons in response to particular stimuli that requires averaging many EEG recordings