(Ch. 3-4) Neuroscience and Behavior... Sensation/Perception

Question 1

What is the difference between sensation and perception?

Answer 1

Perception is the organization and interpretation of sensations. They are put together by the brain

Question 2

What is transduction?

Answer 2

The process our senses depend on to convert physical signs in the environment into encoded nueral signals sent to the central nervous system. Ex. enjoying an ice cream sundae. The sweet taste is registered in your brain through transduction

Question 3

What are some of the main concepts of psychophysics (i.e. JND)?

Answer 3

Psychophysics measures the strength of a stimulus and an observer’s sensitivity to that stimulus.

• Difference and absolute thresholds
• Absolute threshold (smallest intensity needed to just barely detect a stimulus
• JND (just noticeable difference, or the smallest change in a stimulus that can be barely detected)
• Weber’s Law
• Signal detection
• Sensory adaptation

Question 4

Signal Detection Theory

Answer 4

SDT: allows researchers to distinguish between an observer’s perceptual sensitivity to a stimulus and criteria for making decisions about the stimulus (way to measure perceptual sensitivity)

Question 5

Sensory Adaptation

Answer 5

SA: occurs because sensitivity to lengthy stimulation tends to decline over time

Question 6

Retina

Answer 6

• links the world of light outside the body to the world of vision inside the central nervous system
• contains photoreceptor cells (cones and rods)
• outermost layers consist of retinal RGC’s that collect and send signals to the brain; each RGC is responsible for picking up light falling within a small receptive field
• when light strikes the retina, specific patterns respond in each of the 3 cone types (critical to color perception); short wavelength is bluish, medium is greenish, long is reddish; these codes of color are the trichromatic color representations
• info encoded by the retina travels to the brain along the optic nerve

Question 7

Rods

Answer 7

• active under low-light conditions (night vision)

- 120 million rods distributed around each retina (except in fovea)

Question 8

Cones

Answer 8

• detect color under normal daylight conditions
• allow us to focus on fine details
• 6 million cones around each retina, densely packed in the fovea and more scattered elsewhere
• explains why peripheral vision isn’t as clear

Question 9

Theories of color vision

Answer 9

OPPONENT PROCESS THEORY
-cones see colors in opposition to each other

TRI-CHROMATIC THEORY
-3 different kinds of cones see 3 different colors, varying levels of each create colors we see
Retinex theory
-all colors we see are completely made up by our brains

Question 10

Brain areas responsible for vision and what they do (i.e. V1, occipital lobe)

Answer 10

• information encoded in the retina travels to the brain along the optic nerve, through the optic chasm, down the optic tract, which connects to the lateral geniculate nucleus in the thalamus, and then to the primary visual cortex, area V1, in the occipital lobe
• Area V1, the primary visual cortex, is where info is systematically mapped into a representation of a visual scene. (located in the back of the brain)
• 30-50 brain areas specialized for vision located in the occipital lobe and in the temporal lobes

Question 11

How we organize what we see in coherent objects of perception

Answer 11

Two distinct pathways from the occipital lobe

Ventral stream: travels in the lower levels of the temporal lobes; includes areas that represent an object’s shape and identity

Dorsal Stream: occipital lobes to the parietal, upper parts of brain; identify the location and motion of an object

Question 12

Perceptual Constancy

Answer 12

even as sensory signals change, perception remains consistent

Question 13

Gestalt Principles

Answer 13

perceptual grouping, such as simplicity, closure, and continuity, govern how the features and regions of things fit together

Question 14

Image-based recognition theory

Answer 14

an object you have seen before is stored in memory as a template, you recognize objects based on templates stored in your brain

Question 15

Parts-based recognition theory

Answer 15

the brain reconstructs objects into a collection of parts; objects stored as structural descriptions and inventories

Question 16

Monocular Cues

Answer 16

• -yield info about depth when viewed with only one eye–
• Linear perspective: parallel lines seem to converge as they recede into the distance
• Texture gradient: patterned surfaces, and the distance, grow smaller as the surface is farther away
• Interposition: when objects are blocking each other, you can infer that the blocking object is closer than the blocked
• Relative height in the image: objects are closer to you when they are lower in your visual field

Question 17

Binocular Cues

Answer 17

the difference in the retinal images of the two eyes that provides information about depth

Question 18

Our experience of motion

Answer 18

We experience motion through the differences in the strengths of output from motion-sensitive neurons. These processes can give rise to illusions such as apparent motion

Question 19

Change vs. Inattentional blindness

Answer 19

• Change and inattentional blindness occur when we fail to notice visible and even salient features of our environment, emphasizing that our conscious visual experience depends on focused attention
• Change is failing to notice a change, and inattentional is failing to perceive an object that is not in the focus of attention

Question 20

Physical properties of sound that map onto our perception of sound

Answer 20

• Frequency: corresponds to our perception of pitch
• Amplitude: corresponds to our perception of loudness
• Complexity: corresponds to our perception of timbre (pure vs complex tones)

Question 21

Components of the ear that facilitate audition

Answer 21

Outer ear: collects sound waves and funnels them toward the middle ear; consists of visible part on outside of head called pinna (auditory canal), and the eardrum

Middle ear: transmits the vibrations to the inner ear; contains the 3 ossicles (smallest bones in the body) that form a lever that mechanically transmits and intensifies vibrations

Inner ear: tranducts vibrations into neural impulses; contains spiral shaped cochlea (fluid filled tube that is the organ of auditory transduction), the basilar membrane (divides the cochlea and undulates when vibrations from ossicles reach cochlear fluid), and hair cells (embedded in the basilar membrane, specialized auditory receptor neurons, when stimulated release neurotransmitter molecules, indicating a neural signal in the auditory nerve that travels to the brain)

Auditory pathway: action potentials from inner ear travel along the pathway through the thalamus to Area A1 (contralateral primary auditory cortex) in the thalamus

Question 22

Place vs. temporal codes, sound localization

Answer 22

Auditory perception depends on both a:
- place code (used mainly for high and frequencies when the cochlea encodes different frequencies at different locations along the basilar membrane) and - temporal code (registers low frequencies via the firing rate of action potentials entering the auditory nerve)

Question 23

Haptic perception, topography of the somatosensory cortex

Answer 23

Haptic perception occurs when we touch and grasp objects with our hands

Somatosensory cortex: along the length of of the parietal lobe and parallel to the motor cortex in the frontal lobe; layered to pick up sensory signals that include vision, taste, hearing, smell, and equilibrium

Question 24

How we experience and can control our experience of pain

Answer 24

The experience of pain depends on signals that travel along two distinct pathways.

• One sends signals to the somatosensory cortex to indicate the location and type of pain.
• The second sends signals to the emotional centers of the brain that result in unpleasant feeling we wish to escape
• Experience of pain varies
• Gate-control theory is a way to control pain (rubbing an injury helps relieve pain), and is explained by bottom up and top down aspects of control)

Question 25

Role of the vestibular system

Answer 25

• responsible for balance
• influenced by vision
• hair cells in the semicircular canals of system detect movement of their fluid when head moves or accelerates
• hair cells encode somatic sensations to somatosensory cortex

Question 26

Processes and components involved in our experience of smell

Answer 26

• odorant molecules make their way into our noses in the air we breathe
• the olfactory epithelium contains 10 million olfactory receptor neurons
• olfactory receptor neurons (ORN’s) are receptor cells that initiate the sense of smell; if enough molecules bind to sites, they send action potentials to the olfactory nerve
• each olfactory neuron has receptors that bind to specific odorants, as if receptor is a lock and odorant is a key
• ORNS send axons from olfactory epithelium to olfactory bulb
• olfactory bulb is a brain structure located above the nasal cavity beneath the frontal lobes; contains glomerulus
• glomerulus is a convergence site for ORN axons
• Pheromones are biochemical odorants emitted by other members of ones species that affect the animals behavior or physiology

Question 27

Role of smell in social behavior, function of pheromones

Answer 27

• explained by pheromones, which activate the hypothalamus

- affect biochemical responses to our environment

Question 28

Processes and components involved in our experience of taste

Answer 28

Tongue is major organ involved in taste

• covered in papillae, or small bumps
• each papillae contains hundreds of taste buds, these fade with age
• each taste bud contains varying types of receptor cells, whose tips, called microvilli react with tastant molecules in food
• each taste bud contacts the branch of a cranial nerve at its base

Question 29

Properties of Light waves

Answer 29

Length: hue or color
Amplitude: brightness
Puritiy: saturation, or richness of color

Question 30

Purpose, function, and composition of neurons

Answer 30

• cells that perform information-processing tasks, the “thinking” cells
• made up on axons, dendrites, cell body, and myelin sheathing

Question 31

How neurons communicate

Answer 31

• communicate via dendrites, axons, synapses, and electrical signals
• signal travels from axon of one cell, across a synapse, to dendrite of another cell, to cell body, to axon, to synapse, and so on

Question 32

Why and how neurons are different/specialized

Answer 32

• sensory neurons receive info from external world and convey info to the brain via spinal cord
• motor neurons carry signals from spinal cord to muscles to produce movement
• interneurons connect sensory neurons, motor neurons, and interneurons
• interneurons work in small circuits to perform simple tasks (recognize location of sound) to complex ones (recognizing familiar faces)
• purkinje cells carry info from cerebellum to rest of the brain and spinal cord
• pyramidal cells exist in cerebral cortex
• bipolar cell (type of sensory neuron) exist in retinas of eye, have a single axon, and a long dendrite

Question 33

The components and operation of an action potential

Answer 33

• action potential= electrical signal that is conducted along length of a neuron’s axon to the synapse
• occurs only when the electrical shock reaches a certain threshold
• AP is all or none, electric stimulation below threshold fails to produce AP
• electric stimulation of the neuron shuts down the K+ channels and opens the Na+ channels, allowing Na+ to rush in and increase the positive charge inside the axon relative to the outside, triggering the action potential
• period of time where charge returns to neutral is called refractory period, where chemical pump is at work

Question 34

What happens at the synapse, role of neurotransmitters

Answer 34

• synapse= junction or region between axon of one neuron and dendrites or cell body of another
• neurotransmitters= chemicals that transmit info across synapse to a receiving neuron’s dendrites, to a receptor, which either initiates or prevents a new electrical signal
• at the synapse, 1) AP travels down axon and 2) stimulates release of neurotransmitters from vesicles. 3) neurotransmitters are released into synapse, where they float and bind w/ receptor sites in a dendrite of a postsynaptic neuron, making a new AP. 4) neurotransmitters are cleared out of synapse by reuptake into sending neuron, 5) being broken down by enzymes in the synapse, or 6) binding to autoreceptors on the sending neuron

Question 35

Breakdown, subdivision, and function, of components of the nervous system

Answer 35

• central nervous system consists of brain and spinal cord
• peripheral nervous system connects the central nervous system to the body’s organs and muscles
• somatic nervous system- set of nerves that conveys info into and out of the central nervous system
• autonomic nervous system- set of nerves that carries involuntary and automatic commands that control blood vessels, organs, and glands
• sympathetic nervous system- set of nerves that prepares the body for action in threatening situations
• parasympathetic nervous system- helps the body return to a normal resting state
• spinal reflexes- simple pathways in the nervous system that rapidly generate muscle contractions