How do we sense perceive and see the world Flashcards
the only input our brain receives from the “real” world is a series of?
action potentials passed along the neurons of our various sensory pathways
specialized cells that transduce (convert) sensory energy into neural activity
sensory receptors
each sensory systems receptors are designed to respond to ? give 4 sensory systems and what they respond to
only a narrow band of energy
- vision: light energy produces chemical energy
- auditory: air pressure produces mechanical energy
- somatosensory: mechanical energy
- taste and olfaction: chemical molecules
specific part of the world to which a sensory receptor organ responds
receptive field
stream of visual stimuli that accompanies an observers forward movement through space
optic flow
change in sound heard as a person and sound sources pass each other
auditory flow
each photoreceptor has a unique___ that partially ___ with _____
receptive filed, overlaps, adjacent field
by overlapping receptive fields we can?
check information against each other (more accurate)
___ is important for determining the sensitivity of a sensory system
example?
density
–> ore tactile receptors on the fingers than on the arms
differences in receptor ___ determine the special abilities of animals
-density
ex, olfactory ability of dogs
explain a neural relay and what happens at different stages of a neural relay
- all receptors connect to the cortex through a sequence of 3 or 4 intervening neurons, information can be modified at various stages in the relay,
(the info that reaches the primary cortex is not the same as the info that enters our receptors)
what does information being modified at various stages of the neural relay allows the sensory system to do?
mediate different responses
sensory neural relays are central to the hierarchy of>
motor responses in the CNS
sensory info is encoded by ____ that travel along peripheral nerves to the __
action potentials, CNS
different sensations are produced in ?
different areas of the cortex
how do we learn to distinguish our senses
through experiences
each system has distinct wiring set up at ___ of neural organization
all levels
presence of a stimulus will ___ our potential for an AP
increase
The ____represents the sensory field of each modality: vision, hearing, touch, smell, and taste—as a spatially organized neural representation of the external world
neocortex
the ___ is a neural- spatial representation of the body or of the areas of the sensory world perceived by a sensory organ
topographic map (more cortical area for different senses)
Registration of physical stimuli from the environment by the sensory organs
Sensation
Subjective interpretation of sensations by the brain
perception
___ is our primary sensory experience
what does this mean for brain organization?
vision
- far more of the brain is dedicated to vision than to any other sense
Light-sensitive surface at the back of the eye; consists of neurons and photoreceptor cell
retina
3 functions of the retina
- translates light into action potentials
- discriminates wavelengths (colours)
- works in a wide range of light intensities
region of the center of the retina that is specialized for high acuity
fovea
receptive field at the center of the eyes visual field
fovea
where is vision the best
in the center of the visual field
where is our blind spot
region of the retina (known as the optic disc) where axons forming the optic nerve leave the eye and where blood vessels enter and leave
the blind spot has no?
photoreceptors
swollen optic disc
papilledema
papilledema may be due to?
hgih intracranial pressure (tumour in the brain or infection) or inflammation of the optic nerve (optic neuritis)
can pailedema cause loss of vision
yes
you optic disc is in ____ in each eye
a different spot
where is the optic disc located relative tot eh fovea in the left and right eye?
- lateral to the fovea in each eye
Rods:
- ___numerous then cones
- sensitive to ___ levels of light
- used mainly for ?
- __ types of pigment
- more
- low levels (dim light)
- night vision
- 1
cones:
- highly responsive to ___ levels of light
- specialized for ?
- in the __ only
- __ types of pigment
- bright light
- colour and high visual acuity
- fovea
- 3
responsible for colour and our ability to see fine detail
cones
the 3 types of cone pigments absorb light over a range of frequencies, but their maximal absorptions are? for what colour?
- 419nm short wavelengths (blue)
- 531nm middle wavelengths (green)
- 559nm long wavelength (red)
are there equal numbers of all cones?
no. ~ equal amounts of red and green but less blue
4 types of retinal neurons in order that light travels and what they do
- Bipolar cell: recieves input from photoreceptors
- Horizontal cell: links photoreceptors and bipolar cells
- Amacrine cell: links bipolar and ganglion cells
- Retinal ganglion cell: gives rise to the optic nerve
light has to pass through all the layers of retinal neurons before reaching?
cones and rods
2 types of ganglion cells and what they do
- Magnocellular cell: LARGE
- -> receive input from primarily rods, sensitive to light and moving stimulus - Parvocellular cell: small
- -> receives input from primarily cones, sensitive to colour
what layers of the thalamus are for the magnocellular layers? and what layers are the parvocellular layers
Mcells: 1-2
Pcells: 3-6
what thalamus layer has high acuity
parvo
junction of the optic nerves from each eye
optic chiasm
axons from the nasal side (inside) of the each retina go to ____ sides of brain
axons from temporal (outside) half of each retina go to ___ sides of brain
- contralateral
- ipsilateral
light that falls on the right half of each eye comes from the ___ visual field so it goes to the ___ hemisphere of brain
- left , right
3 routes to the visual brain
- geniculostriate system
- tectopulvinar system
- retinohypothalamic tract
describe route or geniculostriate system
Projections from the retina to the lateral geniculate nucleus to the visual cortex
describe the route of the tectopulvinar system
Projections from the retina to the superior colliculus to the pulvinar (thalamus) to the parietal and temporal visual area
describe the route of the retinohypothalamic tract
synapses in the tiny suprachiasmatic nucleus in the hypothalamus
the retinohypothalamic tract play a role in?
regulating circadian rhythms and in the pupillary reflex
most information flows through what 2 tracts
geniculostriate and tectopulvinar
2 paths originate form the striate cortex (region V1) : where do these routes go?
- one goes to the vision-related regions of the parietal lobe
- one goes to the vision related regions of the temporal lobe
- Pathway that originates in the occipital cortex and projects to the parietal cortex
- Pathway that originates in the occipital cortex and projects to the temporal cortex
- dorsal
- ventral
- the right LGN receives input from the ___ half of each retina
- the left LGN receives info from the __ half of each retina
- right
- left
6 layers of the LGN (thalamus) : layers 1, 4, 6: layers 2,3, 5: layers 1-2: layers 3-6:
- input from contralateral retina
- input from ipsilateral retina
- input from magnocellular cells
- input from parvocellular cells
P and M retinal ganglion send ___ pathways to the thalamus as well as right and left eyes send ___ pathways to the thalamus
- separate
the cortical column of the geniculostriate pathway is organization that represents a ?
functional unit of 6 cortical layers deep and approx 0.5mm square; perpendicular to the cortical surface
From each lateral geniculate nucleus, information from each retina is sent to ____cortical columns, thus maintaining the separation of information from each retina
adjacent
the cortical columns are in?
V1
in the tectnopulvinar pathway, magnocellular cells from retina project to the superior colliculus whcih send info to the pulvinar (thalamus)
- the medial pulvinar sends connections to?
- and the lateral pulvinar sends info to?
medial –> parietal
lateral–> temporal
occipital cortex is composed of at least how many visual regions
6.
Striate cortex receives input from the lateral geniculate nucleus
primary visual cortex (V1)
Visual cortical areas outside the striate cortex
secondary visual cortex (V2-V5)
tectopulvinar pathway goes to what visual cortex
secondary visual cortex and areas
heterogeneous layering in V1 is divided into ? and ?
blobs and interblobs
Region in the visual cortex V1 that contains color-sensitive neurons
blobs
region in visual cortex V1 that participates in perception fo form and motion
interblobs (region that separates blobs)
blobs were revealed by staining for
cytochrome oxidase
in V2 heterogenuous layering is divided into ?
thick stripes, thin stripes and pale zones
in V2, receive information from movement-sensitive neurons
thick stripes
in V2, receive information from color-sensitive neurons
thin stripes
in V2, receive information from form-sensitive neurons
pale zones
fusiform face area: parahippocampal place area: lateral intraparietal area: anterior intraparietal area: parietal reach region:
- faces
- scenes
- eye movements
- visual control of grasping
- visually guided grasping
facial agnosia and prospagnosia
unable to recognize faces
