2 Sensation and perception Flashcards
What are osmoreceptors?
Receptors that respond to the osmolarity of the blood (water/hydration homeostasis)
What is the absolute threshold in terms of sensation and perception? What is the difference threshold?
The minimum intensity at which a stimulus will be transduced (converted into action potentials).
The threshold is also called a limina, and a stimulus under the threshold is subliminal (will still have an effect on sensory apparatus - e.g. moving hairs in fluid of middle ear - but will not be enough of a stimulus to trigger an action potential and subsequent perception of the stimulus).
The difference threshold (or just noticeable difference) refers to the minimum difference in magnitude between two stimuli before one can perceive a difference (e.g. between two similar shades of blue).
What is Weber’s law?
The difference threshold (or just noticeable difference) refers to the minimum difference in magnitude between two stimuli before one can perceive a difference (e.g. between two similar shades of blue).
Weber’s law states that there is a constant ratio between the change in stimulus magnitude needed to produce a just noticeable difference and the magnitude of the original stimulus. Thus, for higher magnitude stimuli, the actual difference must be larger to produce a jnd.
Calculate jnd as a percentage. e.g. 440 Hz vs 443 Hz: jnd = 3/440 = 0.68%
Weber’s law seems to be accurate except for extremes
What is signal detection theory?
The intersection between psychophysics (e.g. difference threshold) and psychology (e.g. priming/personality etc.)
Detecting a signal isn’t just physical (external), but also based on internal psychology.
What is physical evidence on the retina that color vision has a greater sensitivity for fine detail than black-and-white vision?
Three types of cones for three colours (RGB). Rods detect black-and-white. There are more rods that converge into a single ganglion through bipolar neurons than cones that converge into a single ganglion through bipolar neurons.
The more neurons that converge into a ganglion the lower the resolution as the ganglion has to represent the activity of a wider area of photoreceptors.
What are amacrine and horizontal cells?
Part of vision. They receive input from multiple retinal cells in the same area before the information is passed on to ganglion cells. They can thereby accentuate slight differences between the visual information in each bipolar cell. These cells are important for edge detection, as they increase our perception of contrast.
Which cells in the visual pathway detect shape?
Parvocellular cells detect shape and can make things out from the background (and fine details). They are bad with moving stimulus (poor temporal resolution)
What cells in the visual pathway detect motion?
magnocellular cells detect movement because they have very high temporal resolution. However, they don’t have good spatial resolution like parvocellular cells so they are bad at detecting details (they provide a blurry but moving image of an object)
Describe the ear as you get deeper into it’s structure
OUTER EAR
- Pinna (auricle) cartilaginous outside of ear directs sound waves into ear
- External auditory canal
- Tympanic membrane (vibrates in pahse with sound waves and volume by amplitude of waves)
MIDDLE EAR
- Eustachian tube via nasal cavity
- Ossicles (malleus (hammer), incus (anvil), and stapes (stirrup)).
- Stapes rests on oval window of cochlea
Inner ear
- cochlea
- vestibule
- semicircular canals
Describe the fluids of the ear (2)
- Endolymph (potassium rich inside the membraneous labyrinth of the cochlea, vestibule, and semicircular canals
- Perilymph surrounds the membraneous labyrinch in the cochlea, vestibule, and semicircular canals to suspend them within the bony labyrinch. Perilymph helps transmit vibrations from the outside world and cushions inner ear structures
Describe the cochlea
- inner ear
- spiral shaped
- divided into 3 parts called scalae,
- middle scalae has organ of corti, which has cilia on a basilar membrane that are moved by the movement of the water from the stapes moving the oval window
- Organ of Corti converts the physical stimulus into an electrical one that travels in the vestibulocochlear nerve
What is the vestibule of the inner ear?
A portion of the bony labyrinth that contains the utricle and saccule, structures that are sensitive to linear acceleration (balancing and orientation in 3D space)
- Modified hair cells called otoliths resist motion when the body accelerates, bending and sending a signal to the brain.
What are the semicircular canals of the inner ear?
Semicircular canals are sensitive to rotational acceleration (in contrast to the vestibule, which is linear acceleration). Refine head rotation and position in 3D space with hair cells within ampulla
Give the auditory pathways and the three locations the signal can end up
- vestibulocochlear nerve
- thalamus: medial genicular nucleus (MGN)
- auditory cortex (sound processing)/superior olive (sound localizing)/inferior colliculus (startle head-turn reflex/vestibulo-ocular reflex)
How do hair cells generate action potentials in the inner ear?
When hair cells are bent ion channels open, generating an action potential.
