PYSC 230 Module 4

Question 1

What is Sensation?

Answer 1

Sensation: The stimulation of sensory receptors and the transmission of sensory information of the CNS. This is a mechanical process, as it involves the activation of receptors as well as the transduction of physical energy into a neural impulse. As it pertains to vision, transduction involves the translation of photonic by photoreceptors stimulation into a neural impulse.

Question 2

What is Perception?

Answer 2

Perception: The process by which organized into an inner representation of the world. Perception involves assigning meaning to the sensory experience. This describes a physiological experience that is coupled with awareness.

Question 3

Absolute Threshold

Answer 3

Absolute Threshold: The minimum amount of energy that can produce a sensation on 50% of the trials. The minimal difference in intensity required between two sources of energy so they will be preceded as being different

Question 4

Webers Law

Answer 4

Weber’s Law: Describes a constant of a proportion of the original stimulus by which the stimulus has to be increased or decreased in order for a difference to be detected. Weber’s law for weight perception is 1/20 or 5%.

Question 5

Rods Vs. Cones

Answer 5

Rods: Rod-shaped photoreceptors that are sensitive only to the intensity of light, they are active during dimly-lit conditions and produce black and white images. Located on the periphery of the retina, they also outnumber cons 20:1.

Dark Adaption: The process of adjusting to lower lighting, requires about 10mins, robs take up to 45mins to adapt.

Cones: Cone-shaped photoreceptors that transmit sensations of colour, active during brightly lit conditions and produce sensations of colour images. Located in the fovea of the eye (center of the retina).

Light Adaption: Process of adjusting to bright lights. A large number of rods and cones are bleached at once, occurs very fast.

Question 6

Opponent Process

Answer 6

Opponent Process Theory: proposes that colour vision is made possible by retinal ganglion cells that respond to pairs of colours. These specialized cells process information from the cones and compute the differences between the 2 colours. Cells respond in antagonist ways to red vs. green, blue vs. yellow, and black vs. white. (account for the after-image effect).

Question 7

Bottom-up process

Answer 7

Bottom-up Process: The organization of the parts to recognize or form an image of the pattern they compose, builds up the perceptual experience from individual pieces.

Question 8

Top-Down Processing

Answer 8

Top-Down Processing: The use of contextual information or knowledge of a pattern in order to organize parts of the pattern. Perception guided by prior knowledge or expectations.

Question 9

The process by which one form of energy is converted to another:

Answer 9

Sensory Transduction: The transformation of the energy of a stimulus into a change in the electrical potential across the membranes of the receptor.

Question 10

Transduction

Answer 10

Transduction: Process by which receptors translate sensory stimulation into a neural signal for processing in the brain. - One form of energy to another.

Question 11

Visual Input to the Brain

Answer 11

Visual Input to the Brain: First transduction of light occurs in the retina and photoreceptors (rods and cones). The signal travels through the optic nerve and reaches the primary visual cortex, where processing for light orientation and movement occurs.

Question 12

Ventral Pathway

Answer 12

Ventral Pathway: Originates in the primary visual cortex of the occipital lobe and terminates in areas of the temporal lobe involved in object recognition.
For example, the fusiform gyrus is specialized for the recognition of faces. Damage to the fusiform gyrus results in prosopagnosia, which is characterized by an inability to recognize faces.

Question 13

Dorsal Pathway

Answer 13

Dorsal Pathway: Originates in the primary visual cortex of the occipital lobe and terminates in areas of the parietal lobe involved in gliding movements. Damage to this results in hemispatial neglect which is characterized by an inability to process information arising from the positive side of the body as well as that arising from the opposite side of one’s visual field.

Question 14

Audition

Answer 14

One of the most important principles of hearing is frequency analysis which occurs in the cochlea. Complex sounds are broken down into their constituent frequencies, with each frequency activating a discrete location of the basilar membrane.

Question 15

Low vs high frequency

Answer 15

Low frequencies: creating maximum basilar membrane vibrations at the apex of the peak of the cochlea.

High frequencies: create maxima basilar membrane vibrations at the base of the cochlea.

Question 16

Parts of the ear:

6 parts

Answer 16

Pinna: the visible part of the ear, filter soundwaves and aids with the localization of sounds

Canal: The space leading to the tympanic membrane

Tympanic Membrane: also known as the eardrum, separation of the middle and outer ear. Vibrations in response to sound and thereby transmits them to the middle and inner ear. Amplifies sound

Middle ear: Consists of the Malleus (hammer), Incus (anvil), and Stapes (stirrup). Transmits the vibrations from the tympanic membrane to the oval window of the cochlea. Increases pressures of the vibrations.

Inner ear:

Cochlea: Encased in the temporal bone of the skull, snail-shaped bone structure full of fluid. Contains the basilar membrane and the organ of Corti. Contains the auditory cells - hairlike vells which transduces sound into electrical potentials.

Hair cells: Response to the vibrations of the vascular membrane

Question 17

Vestibular System

Answer 17

Vestibular system: A sensory system that is responsible for providing our brain with information about motion, head position, and spatial orientation.

The vestibular system in general helps us to maintain our balance and stabilize our eyes during head motion.

Along with audition, the inner ear is responsible for encoding information about equilibrium, i.e. the sense of balance. A similar mechanoreceptor a hair cell with stereocilia sense head position/movement, and whether our bodies are in motion

Head position is sensed by the utricle and saccule and head movement is sensed by the semicircular cancels. These structures in the vestibular system sense both linear acceleration and gravity.

Question 18

Semi-Circular Canels

Answer 18

The semi-circular cancels are three ring-like canals. Rotation of the head about these axes activates the semicircular cancels, which are responsible for sensing rotational or angular accelerations of the head. When the head rotates in a plane parallel to one of the semi-circular canals, the fluid lags, deflecting the ampullae (protrusion at the base of each canal) in the direction opposite to the head movement. The ampullae contain the hair cells that respond to rotational movements.

Question 19

Linear vs Angular vs Tilt

Answer 19

Linear motion: can be sensed when accelerating or decelerating in a car
Angular motion: can be sensed when rotating the head from side to side
Tilt: the tilt of the head in any direction and well as when you node “yes”.
When it comes to detecting angular velocity, at the base of each of the semicircular canals are the ampullae which contain the hair cells responding to rotational movement.

Question 20

Somostosensation

Answer 20

Somostosensation: The ability to sense touch, vibration, pain, temperature, pressure, and joint position.

Question 21

Somatotopic Map

Answer 21

Somatotopic Map: Organization of the primary somatosensory cortex maintaining a representation of the arrangement of the body.
The size of the cortical regions is based on the sensitivity, and not the size, of the specific parts of the opposite side of the body.