PSYCH 120A - Midterm Flashcards

neuron

a specialized cell transmitting nerve impulses; a nerve cell

dendrite

receives input from other neurons; input

soma

cell body; integration; contains the nucleus and cellular machinery, integrates incoming signals

axon

output; transmits signals to other neurons

glial cells

other types of brain cells that support neuronal health, guide development of nervous system, control nutrient flow (not neurons)

myelin

fatty substance that coats and protects the axon

action potential

electrical impulse that travels down the axon triggering the release of neurotransmitters; all-or-nothing response

neurotransmitters

chemical messengers contained in synaptic vesicles; different types of neurotransmitters either excite (activate) or inhibit the post-synaptic neuron

synapse

space where axon terminal contacts the dendrite

receptors

where neurotransmitters bind (on post-synaptic dendrite) and influence its activation state; continues signal transmission process

neuromodulators

only increases or decreases activation/inhibition in post-synaptic neuron

Important because:

* Make sure you form a memory (attend to behavioral information + store it for the long term)
* Neuromodulators function for most salient experiences (dopamine + norepinephrine potentiate activity)
* Inhibition = just as important as excitation (tune out distractions + spotlight key experiences)

cerebral cortex

outer layer of brain tissue

sulcus

grove in the surface of the brain (valley)

gyrus

ridge or fold on the cerebral surface of the brain (peak)

gray matter

contains cell bodies of neurons (not myelinated)

white matter

contains axons (myelinated)

Diffusion Tensor Imaging (DTI)

MRI-based technique to image white matter pathways (looks at diffusion of water to trace orientation + direction of neurons)

frontal lobe

"higher order" cognition; problem-solving; working memory

temporal lobe

object processing/naming, auditory processing, memory (especially in medial level), language

cerebellum

evolutionarily much older than other structures

occipital lobe

visual information

parietal lobe

imagery, memory retrieval, spatial attention, multi-sensory integration ("moves the spotlight" of attention)

central fissure

separates frontal lobe from parietal lobe

lateral fissure

separates frontal lobe from temporal lobe

motor cortex

controls voluntary movements

somatosensory cortex

registers and processes body touch and movement sensations

homonculus

* showcases scale of sensory real estate based on importance to daily function
* A rendering of the body in which each part is shown in proportion to show how much of the somatosensory cortex is devoted to it

primary cortex

first region to process information in a given modality (e.g., basic visual information, like lines)

secondary cortex

supports more complex processing of a given sensory modality (e.g., assembling lines into object representations)

higher-order cortex

regions that integrate different sensory inputs

corpus callosum

major white matter pathway that connects the two hemispheres of brain

left hemisphere

predominantly supports language function

right hemisphere

responsible for visual-spatial processing

hippocampus

* Contributes to acquisition, storage and retrieval (sometimes) of unique memories
* Takes disparate elements of sensory information + weaves them together + binds them into a cohesive episode
* "Author" but not library that holds book

amygdala

* plays key role in encoding, storing, and retrieving highly emotional memories
* Important for implicit AND explicit memory
* Responds to & regulates stress (flight or fight) response

olfactory bulb

primary organ in brain for processing odors (connected to amygdala--tied to emotional memory)

thalamus

* brain's relay station; connects many parts of brain (centralized)
* “Grand Central Station”

basal ganglia

* complex group of nuclei in middle of brain
* memories of motor, habits or automatic skills (largely unconscious)

human visual system

Light --\> Retina --\> Optic Nerve --\> Thalamus (LGN) --\> Primary Visual Cortex --\> Visual Streams

pupil

dilates depending on light (open more, lets more light in)

LGN (lateral geniculate nucleus)

nucleus of thalamus that's devoted to processing visual information; relays information back to occipital lobe (V1)

Primary Visual Cortex (V1)

passes visual info forward through visual streams

optic nerve

* carries neural impulses from the eye to the brain
* responsible for blind spot because you need axons from ganglion cells to pass out of eye somewhere--> dense bundle of ganglion axons = where info exits the eye; there are no photoreceptors here bc space is occupied (not detecting visual field)

rods

* sensitive to dim light (i.e., low levels of light)
* Lower acuity
* Color-blind
* None in the fovea

cones

* cannot function in dim light
* higher acuity
* color sensitive mostly in or near the fovea; none in the periphery

fovea

center of the field of vision and has dense concentration of cones (therefore high visual acuity)

photoreceptors

rods + cones

bipolar cells

transmit signals from photoreceptors to ganglion cells

ganglion cells

transmit signals out of optic nerve to LGN

receptive field

area of visual field that elicits stimulation

single-unit recording

recording of the electrical activity of a single neuron; used to measure subjects' receptive field

center-surround organization

* If you point light in middle of visual field, you get positive stimulation Enhanced firing rate of neurons
* If you point light away from visual field (off-center, surround) , you suppress firing rate of neurons (inhibition)

edge detectors

* detectors fire when stimulus within receptive field contains edge of particular orientation (less the edge is like the cell's "preferred" edge, the less often the neuron fires)
* In primary visual cortex-V1

parallel processing

ventral stream + dorsal stream

ventral stream

"what pathway"; carries color, shape, and object information (identity); like looking down in front of you; temporal lobe

dorsal stream

"where pathway"; carries space and movement information; like looking up at a lighthouse; parietal lobe (location)

binding problem

how to reintegrate elements of a scene that were processed separately?

neural synchrony

brain seems to register synchronized firing as a cue that the [brain] attributes belong to a single object

spatial position

overlap map of "what forms are where" with map of "what colors are where" and so on

Gestalt principles

ways for the brain to infer missing parts of a picture when a picture is incomplete

figure-ground

* elements are perceived as either figures (distinct elements of focus) or ground (the background on which the figures rest)
* Background vs. Foreground (object of your perception)
* Percept (visual information) is same, but interpretation is different

proximity

things that are close to one another are perceived to be more related than things that are spaced farther apart

similarity

things that are similar are perceived to be more related than things that are dissimilar

good continuation (continuity)

elements arranged on a line or curve are perceived to be more related than elements not on the line or curve

closure

incomplete objects will tend to be perceived as wholes

symmetry and order

ambiguous shapes are perceived in as simple a manner as possible

common fate

things will be grouped together if they point to or are moving in the same direction

perceptual constancy

we perceive constant object properties (sizes, shapes, etc.) even though sensory information about these attributes changes when viewing circumstances change

brightness constancy

* you correctly perceive the brightness of objects whether they're illuminated by dim light or strong sun
* our brain does not directly perceive the true brightness of objects in the world, but instead compares the brightness of a given item with others in its vicinity

contrast effect

* leads to the dark square appearing even darker when surrounded by white squares: due to lateral inhibition
* Brain takes shadow into account to judge brightness --> unconscious inference

color constancy

our brain does not directly perceive the true color of objects in the world, but instead compares the color of a given item with others in its vicinity (\#TheDress)

size constancy

you correctly perceive an objects size despite the changes in retinal-image size created by changes in viewing distance

shape constancy

correct perception of an object's shape despite change in its shape on the retina (door is still seen as rectangle when at trapezoidal angle)

unconscious inference

theory that some of our perceptions are the result of unconscious assumptions that we make about the environment

illusion

erroneous perception of reality

Ponzo illusion

our brain uses distance cues when making a judgment about the length/size of the target object

object recognition

central purpose of perception; how we interact with things in world

hierarchical organization of visual perception

* Info fans out from V1 (occipital lobe) through 2 visual streams (dorsal + ventral)
* Prior Knowledge = constantly interacting bidirectionally w/lower level vision processing

bottom-up processing

building perception from ground up (sensory driven)

top-down processing

coming from executive; higher order cognitive processing regions of brain are using context, prior knowledge, expectations to inform how new information will be processed

viewpoint invariance

* ability to recognize an object seen from different angles
* even though features hitting retina are different, we still know how to categorize same vs. separate objects

mental images

mental representations stored in LTM; our database of different object images

template theory

* matching representation to raw data for categorization
* comparing current visual input (STM) + how it matches to prior template (LTM)
* PROS: works when stimulus = matches brain template (stored in LTM)
* CONS: no perfect match in memory (too many views possible); doesn't work for novel objects

feature theories

* Recognize objects based on a small number of characteristics (features)
* Each object is broken down into its constituent features
* Visual features = alphabet to form objects
* CONS: Doesn’t factor how features relate to each other

Recognition by Components (RBC) Theory

* describes how 3D images are identified--by geons and relationships between them
* PROS: Better at accounting for configural (structural) relationship between shapes -- better than simple features approach
* CONS:
* Shape/structural description not enough--also need metric info
* Doesn't account for how color, texture, other visual details are processed
* Difficult to extract geons from real images
* Some evidence of viewpoint dependence (seeing flat side of 3D object)
* Doesn’t account for top-down effects on recognition (RBC = bottom-up recognition)

geons

* Geometrical shapes that are 3D --> puzzle pieces of visual recognition
* Recognition involves recognizing object elements + configurations; relations are spatial (above/below) and approximate (neighboring)

top-down modulation of visual processing

* Top-down modulation comes from prefrontal cortex
* Sends neural inputs down to early visual cortex (V1) to shape way new information is processed
* Ex: V1 neurons may fire differently from **expectation** to see a dog

word frequency effect

* words that are more frequent in language are better recognized
* Common nodes have lower activation thresholds

word recency effect

* (repetition priming) words that have been recently seen are better recognized; they are primed (facilitated processing due to recent encounter)
* Recent firing brings a node closer to activation later on

word superiority effect

people are more accurate in recognizing a letter in the context of a word than when the letter is presented in isolation, or in the context of a non-word

feature net

* network of nodes and edges (hierarchical processing)
* Basic idea is that detector nodes must reach an activation threshold
* Each detector has a different activation level - With input, this activation level increases
* Detectors "fire" when their response threshold is reached (if it doesn't fire, it will not be detected)

over-regularization

cost to priming; ex: reading CQRN as CORN

Goals of neuroimaging techniques

* Structural: See which differences in volumes; structural connections between brain regions
* Diagnosis: Various clinical differentiations (e.g., presence of amyloid plaques indication of Alzheimer's Disease)
* Functional: Which regions are more/less active during a task; functional connections (when part of the brain is more active, it needs more resources: oxygen, various metabolic supplies, and of course blood)

PET (positron emission tomography) imaging

* Visualizes active brain areas via a small injection of a radioactive substance (called a "tracer") into the blood
* The tracer reveals where blood is going, indexing areas that are active and need oxygen/metabolic supplies: indirect measure of brain activity
* CONS: slow measurements, expensive, risky (invasive injection)
* PROS: different radiotracers can also bind to specific brain receptors, revealing where specific neurotransmitter is influencing brain activity); can study neurochemistry of brain + specific neurotransmitter systems; helps in diagnosis of disorders

fMRI (functional magnetic resonance) imaging

* measures brain FUNCTION
* Used to examine where brain is active during cognitive task, including memory processes
* Indirectly measures blood-flow based on oxygen signal (which perturbs local magnetic field)
* CONS: Expensive, loud
* PROS: Good at spatial localization, decent temporal resolution, non-invasive

electroencephalography (EEG)

* oldest neuroimaging technique; uses electrodes to measure electrical output of brain; scalp EEG or intracranial EEG
* More direct measure of brain activity (brain waves or oscillations)
* CONS: poor spatial resolution; records large populations of neurons
* PROS: Fast sampling → able to sample more often; non-invasive; relatively inexpensive

selective attention

Process of directing attention to relevant stimulus in environment (involuntary attention), or to things that are desirable (voluntary/goal directed attention)

attention

* form of mental activity or energy that can be distributed to different tasks
* Selective, moveable, divisible, sustainable, but also LIMITED!

inattentional blindness

* failure to notice existence of unexpected yet fully-visible item
* usually happens when attention is engaged in some other mentally demanding task

change blindness

* failure to notice that some (obvious) aspect of scene has changed
* Important temporal & component (comparing two moments in time to detect a change)
* Engages STM; happens in absence of motion information