WEEK 3 - SENSORY SYSTEMS Flashcards
PERCEPTUAL PROCESS
stimulus in the environment
PERCEPTUAL PROCESS: vision
light is transformed in the eye and hits the retina
iris
coloured area around pupil
pupil
opening in iris letting light pass through
cornea
outer lens bending light to point on retina
lens
changes thickness and curvature to focus near or far - > accommodation
retina
surface lined with receptors: rods and cones
fovea
highest concentration of receptors
optic nerve:
exits eyeball on nasal side
rods
= nighttime system
- way more than cones, outside fovea
- high senstivity: dark adaptation
- poor colour vison
cones
daytime system
mostly in fovea
fewer outside
lower sensitivity, better detailed vision
colour vision
cones:
lateral inhibition - more contrast
rods
summed responses - more sensitivity
lateral inhibition
sending inhibitory signals across the retina
- cells nearby are less responsive
- appear to receive less light
sharpers contrast to emphasize borders
color vision
visibe light
rods: b/w no colour
cones: color vision
optic nerve
nerve bundle that relays signals from the receptors to the brain
*signal encoded into a pattern of action potentials
*origin of blind spot
label
what structure recieves a reveresed image
retina
optic chiasm
splits left/right visual field
*side signal to superior colliculi
lateral geniculate
relay station in thalamus
retinotopic mapping
the way your brain organizes visual information
maintained spatial relationships from retina to LGN to primary visual cortex
dorsal stream
where or how
ends at parietal lobe
object location
guidance of action
ventral stream
what
ends at temportal lobe
object identification, recognition
face rec
recognizing faces
highly specialized ability
newborns show preference for right side up faces, & develops gradually
motion perception brain structure
involves all four cortical lobes
- both dorsal and ventral streams are involved
myopia
nearsightedness
hyperopia
farsightedness
presbyopia
aging leading to less accommodating lens
*correctable with additional lenses or surgery
cataracts
cloudy lens, can be surgically replaced by artificial lens
visual agnosia
seeing but not recognizing
visual agnosia result from
uncorrected blindness
brain damage, specifically in ventral path
prosopagnosia
specific deficit in recognizing faces
prosopagnosia damage from
damage to the fusiform gyrus in inferior temporal lobe
where does the signal from the right eye go
both hemispheres depending on visual field
where do the inputs from the two eyes cross
optic chiasm but only from crossing visual field
what does retinotopic mean
spatial disruption of signals as they arrive on the primary visual cortex
depth perception
difference between two eyes help to see more depth
audition and vision similarities
perceptual process from sensation to perception
coding of waves to neural impulses
tototopic (not retinotopic) organization
multiple paths from primary auditory cortex
sound
air is out into motion which creates standing waves
eardrum
vibrates with air pressure waves
middle ear ossicles
transmit vibration to oval window
oval window
hammer
anvil
stirrup
cochlea
where specific frequencies are encoded
- basilar membrane with hair cells (cilia)
auditory nerve
encodes stimulus aspects and relays this to primary auditory cortex
auditory pathway - from cochlea to
cochlear nucleus
inferior colliculus
medial geniculate nucleus
to primary auditory cortex in superior temporal lob
tonotopic organisation
tones are organized from low (inside) to high (outside) in the cochlea
how are tones organized in the primary auditory cortex
pitch heigh
low (inside), high (outside)
spatial perception hearing
differences in arrival time between two ears lead to a detectable difference that drives localization
what happens when u change the shape of the pina
changes our sound localization
impairments
presbycusis
- hearing loss with age
- supported by multimodal integration
conductive/middle ear deafness
failure to transmit sound waves to the cohclea
nerve or inner ear deafness
failure to transmit nerve impulses to the brain
tinnitus
constant percept without stimulation
can be caused by nerve deadness but also stress
how to treat tinnitus
cognitive behaviour therapy
why do sounds in left and right ear sometimes merge
bilateral processes
mechanical
receptors that respond to pressure, bending, or other distortions
types of mechanical
vestibular, somatosensation (touch, pressure, temp, pain)
chemical receptors
receptors that respond to specific substances
types of chemical receptors
taste, smell
vestibular system
wrapped around cochlea
three semicircular canals filled with hair cells and fluid
signal is processed in brain stem
somatosensory
touc, pressure, pain, itch
- organized in dermatomes and sensory homunculus
different levels of sensitivity in different places
different pathways per type of sensation
chemical - taste
receptors are taste buds on the papilla of the tongue
intended to signal healthy foods
traditional taste: sweet, sour, salt, bitter, umani and oleogustus (oily)
large ind differences in sensitivity, partly accounted for by genetic factors and hormones
chemical - smell
receptors are inside the nose, based on airborne substances
sense of flavour in taste mostly dependent on smell
sensitivity influenced by hormones
Which parts of the cerebral cortex are most likely to deteriorate in Alzheimer’s disease and other conditions?
The areas that mature at the latest age, such as the
prefrontal cortex.
In which areas of the human brain do some new neurons develop during adulthood?
The hippocampus and the basal ganglia
In early brain development, what is the relationship between the sensory systems and muscle movements?
The first muscle movements occur before the sensory
systems develop.
When Sperry cut a newt’s optic nerve and turned the eye upside down, what happened?
B. Axons of the optic nerve grew back to their original
targets.
In the sympathetic nervous system, which of the following prevents apoptosis?
Nerve growth factor
Why does the spinal cord have the right number of axons to innervate all the muscle cells?
The spinal cord makes an excess of neurons, but those
that fail to innervate a muscle die.
- At what age does a person have the largest number of neurons?
Before or shortly after birth
If a pregnant woman drinks alcohol, alcohol harms the brain of the fetus not only while it is in the system, but also while it
is washing away after drinking. What is the danger while alcohol is washing away?
Overstimulation at glutamate synapses can poison the
mitochondria.
In the ferret study, what evidence indicated that visual input to the auditory portions of the brain actually produced a visual
sensation?
D. Ferrets that learned to turn one way in response to
light in the normal eye turned the same way to light in
the rewired eye.
An enriched environment including social interactions promotes growth of axons and dendrites in laboratory rodents.
Physical activity
According to most research, what are the effects of computerized programs to practice memory skills?
Temporary improvement of the skills that were
practiced
If a person is born blind, what happens to the occipital (“visual”) cortex?
C. Its cells become responsive to touch or hearing.
In people who practice violin or other stringed instruments for many years, what changes in the cerebral cortex?
A larger than average portion of the cortex responds
to fingers of the left hand.
What causes musician’s cramp?
Rewiring of the cerebral cortex
What is the most likely biological explanation for increased risky behavior among adolescents?
Increased activity in brain areas that anticipate
reward
- Why do many older people continue to hold important jobs in spite of the declines in memory and brain function that are
known to occur in old age?
