Sensation and Perception

Question 1

What is “Sensation”?

Answer 1

The process of interpreting the world around us

Question 2

What is transduction?

Answer 2

Conversion of different types of energy into information that our brains can make sense of (sensation requires this process)

Question 3

What is “perception”?

Answer 3

Involves the aggression and interpretation of sensory input from raw neural signals into meaningful information

Question 4

Name the 5 senses we possess (and their technical names)

Answer 4

Sight (vision)
Hearing (audition)
Smell (Olfaction)
Taste (gustation)
Touch (somatosensation)

Question 5

What other senses are there?

Answer 5

Balance (vestibulation)
Pain (nociception)
Kinesthesis – awareness of body position and movement (proprioception)
Time (chronoception)
Temperature (thermoception)

Question 6

How do neurons communicate?

Answer 6

by firing electrical pulses

Each pulse is a fixed speed and intensity – one pulse cannot be more intense or faster than the previous one

Question 7

Define sensory coding and give two examples

Answer 7

expresses how different stimuli are encoded by different neural activity patterns

e.g. anatomical and temporal

Question 8

Describe anatomical coding

Answer 8

When a given area in the brain is stimulated (e.g. pressure applied to your arm)

Nerves from this area inform the brain as to which area is being stimulated

Question 9

Describe temporal coding

Answer 9

The rate at which neurons fire can deviate, depending on the intensity of a stimulus

e.g. extreme pain would elicit more pulses per second than moderate pain

Question 10

What are the primary sensory areas

Answer 10

See brain diagram on pp

Question 11

What is the cerebral coretex made of?

Answer 11

Grey matter and 90% of it is the neocoretex
which has 6 layers

Question 12

Name the 6 layers of the neocortex

Answer 12

1 - Glial cells and axons running parallel to the pial surface. Very few cellular bodies. Interconnections within the cortical area

2/3 - small pyramidal cells that project to other cortical brain areas

4 - stellate cells. receive the most afferent signals from the thalamus

5- Big pyramidal cell, origins of the descending pathways towards the spinal cord

6. Neurons that project to the thalamus

Question 13

What does the central sulcus divide?

Answer 13

The frontal and parietal lobes

Question 14

From which views can we look at a scan image?

Answer 14

axial: a horizontal “slice” of the body or brain
coronal: A vertical slice from side to side.
sagittal: A vertical slice from front to back.

Question 15

At what structure do visual signals cross from one hemisphere to the other?

Answer 15

The chiasma

Question 16

What does just noticeable difference (JND) refer to?

Answer 16

smallest change in something that can be noticed

Question 17

What does liberal criterion imply

Answer 17

high false alarms, high hits, no misses

Question 18

what are the major sulci and fissures visible in the lateral view of the central cortex

Answer 18

Left brain:
Pareito-occipital fissure
Sulcus Calcarino

Right brain:
Pre-central Sulcus
Central Sulcus
Post central Sulcus

Question 19

What is the parieto-occipital fissure, and where is it located?

Answer 19

A deep groove (sulcus) on the medial surface of the brain. Between the parietal and occipital lobes.

Question 20

What is sulcus calcarinus and what is its function?

Answer 20

a prominent groove on the medial surface of the occipital lobe, a brain region primarily responsible for processing visual information

Question 21

Where is the Pre-central sulcus and why is it significnt?

Answer 21

This sulcus is positioned parallel to the central sulcus that lies behind it.

Enclose an area known as the precentral gyrus, which contains the regions responsible for controlling voluntary muscle movements in the body

Question 22

What is the central sulcus, and what does it seperate?

Answer 22

The central sulcus is a prominent landmark of the brain, separating the parietal lobe from the frontal lobe and the primary motor cortex from the primary somatosensory cortex

Question 23

What is the post-central sulcus, and what is its function?

Answer 23

A groove in the parietal lobe behind the central sulcus and is responsible for general sensations of touch, pressure, pain, temperature, and proprioception.

Question 24

What are the primary sensory and motor cortices ?

Answer 24

receives sensory inputs directly through the thalamus and indirectly through the somatosensory cortex.

Question 25

How is vision stimulated?

Answer 25

By light energy

Question 26

What are the main components of the eye?

Answer 26

- The lens - The pupil - The cornea - The iris - The retina

Question 27

What are photoreceptor cells?

Answer 27

Specialised cells in the retina convert light into electrical signals and transmit them to the brain for processing. They play a crucial role in vision.

Question 28

What is the function of the ganglion cell in the eye?

Answer 28

Ganglion cells are the projection neurons of the vertebrate retina, conveying information from other retinal neurons to the rest of the brain

Question 29

What is the function of rods in the eye?

Answer 29

Rods are a type of photoreceptor cell in the retina. They are sensitive to light levels and help give us good vision in low light. Low visual acuity black and white, very sensitive (estimated 120 million cells in humans)

Question 30

What is the function of cones

Answer 30

Cones are a type of photoreceptor cell in the retina. They give us our colour vision. High visual acuity (sharpness) colours (estimated 6 million cells in humans)

Question 31

Describe the fovea in the eye

Answer 31

Located at the back of the eye, it is where our vision is the sharpest

Question 32

Describe the blind spot

Answer 32

Where cells from the eye connect to the optic nerve, and so we cannot see anything that falls on that part of the retina

Question 33

Describe the main components of the eye

Answer 33

The cornea - outside surface of the eye, bends light that enters the eye The iris - bands of muscle that contract and relax to regulate how much light enters the eye via the pupil The pupil - openening into the eye, controlled by the iris The lens - can be adjusted to focus on near or far objects The retina - conatins photoreceptor cells stimulated by different qualities of light

Question 34

Distal and Proximal Stimulus

Answer 34

Proximal stimulus: The stimulus as it appears to the sensory receptors Distal stimulus: Actual 3D object out in the world

Question 35

Visual deficits - Myopia

Answer 35

Myopia - short sightedness The eyeball stretches, such that images are no longer projected onto the retina, but instead, just in front of it

Question 36

What are some causes of Myopia?

Answer 36

Near work hypotheses: working too close to computers Visual stimuli hypothesis: lack of normal vision stimulation which impairs optic development

Question 37

What are photopigments, and how do they work in cones?

Answer 37

Photopigments in cones are broken down by certain frequencies of light, allowing cones to respond to specific wavelengths.

Question 38

How do we perceive different colours?

Answer 38

Certain objects reflect different wavelengths of light - this is how we percieve objects of different colours

Question 39

What photopigment is found in rods, and what does it do?

Answer 39

Rhodopsin a photopigment that breaks down easily in response to light, helping us detect light and dark stimuli

Question 40

Why are we essentially colour-blind in our peripheral vision?

Answer 40

Because we have more rods (which dont detect colour) in the periphery of our eye

Question 41

What is one limitation of the trichromatic theory of colour vision?

Answer 41

The trichromatic theory doesn't explain why colours appear in opposing pairs, such as blue vs. yellow or red vs. green.

Question 42

How does surrounding colour affect our perception of colour?

Answer 42

A gray object can appear bluish when surrounded by yellow, or yellowish when surrounded by blue—showing colour contrast effects.

Question 43

What is the opponent theory of colour?

Answer 43

The theory that we have 3 cone types (red, blue and green) which inhibit each other when excited

Question 44

How does the Opponent - Process theory explain how afterimages work?

Answer 44

prolonged excitation of red receptors means that as soon as these receptors are no longer activated, the blue and green receptors suddenly “spring into action”

Question 45

Describe hue as a dimensions of colour

Answer 45

Hue - distinguishes different colours from each other, colours can vary in brightness but share the same hue, e.g. light red, dark red and pale red

Question 46

Describe brightness as a dimension of colour

Answer 46

Differentiates how far a colour is from black (low brightness) or white (high brightness) its a property possessed by both achromatic colours (e.g., colours that have no hue – black white and grey) and chromatic colours (e.g. red, blue, yellow)

Question 47

Describe saturation as a dimension of colour

Answer 47

refers to the purity e.g. colours that have more achromatic colours mixed in are less saturated (less pure) than colours that have fewer achromatic colours

Question 48

What is synaesthesia?

Answer 48

involves a fusion of different senses & input e.g. - grapheme-colour synaesthesia - chromaesthesia - different sounds trigger the sensation of seeing colours - Auditory - tactile Synaeshesia - different sounds trigger tactile sensation in parts of the body