Sensation, perception and neuropsychology Flashcards
What is sensation?
the act of receiving sensory information from the environment so sensory organs can translate/convert environment stimuli to nerve impulses
What is perception?
Once we have received all the sensory information perception in applying meaning to the information. Allowing our brains to make sense of the information. Also involves interpretation, organization and conscious experience
What light can we interprate?
electromagnetic energy called visible light
What is a cornea?
It is where light waves enter. Has transparent protective structure with focusing ability
What is the choroid/ vascular tunic?
Thin layer of tissue surrounding the middle layer of the eye. it keeps the eye alive by providing blood supply
what are the lens?
Located behind the pupil. It is an elastic structure that becomes thinner to focus on things to focus on distant objects and thicker to focus on nearby objects.
What is a pupil?
Has an adjustable opening, controlled by mucles that dilates or constricts to control the amount of light that enters the eye
What is an iris?
The coloured part of your eye that is attached to muscles that expand and contract to control the pupil size
What is the anterior chamber?
Filled with the fluid (vitreous humour). Is located behind cornea and infant of the lens
What is the portions chamber?
Chamber filled with fluid located behind the lens
What is the vitreous humour?
Liquid in chambers that provide nutrients to keep system alive and also removes waste product
What are the types of retina called and what are they
Nasal retina - retina closes to your nose. looks outwards
temporal retina - retina closest to temples. looks inwards
what is monocular blindness?
when u can’t see out of the specific eye at all
what is bitemporal hemianopia ?
when crossing fibers of optic chiasm is damaged then your temporal retina won’t work having blindness in this area .
what is homonymous hemianopia? use left as an e.g
If there is damage in optic tract it causes blindness in the left temporal retina and the right nasal retina.
what is homonymous hemianopia with macular sparing? - use left as an e.g
if there is damage in V1 you still end up with Left homonymous hemianopia with macular sparing. Central vision is spared
what does V5 and V4 do?
v5 - adds motion to the visual picture
v4- adds colour
what is Achromatopsia ?
- damage to v4 in the middle/inferior temporal gyrus which causes there to be an absence of colour vision meaning you will only see the worlds in shades of grey
what is akienetopsia?
damage to v5 in the middle/inferior temporal gyrus causes inability to see the visual world when it is set into motion. See life more in snapshots instead of motion.
What is visual agnosia
An inability to name an object even though you can see it properly
What is Apperceptive agnosia?
- Failure to recognise objects due to a failure of visual perception
- Have peservered elementary visual function
- Poor matching and copying
- due to damage of primary visual cortex in the occipital lobe
What is scotoma?
When a cell in point to point representation of retinal topic mapping is damaged causing a blind spot in the visual field
What is Dorsal simultagnosia?
- Failure of object recognition due to spatial perceptual impairment you can recognise objects but not more then one at a time
- Preserved elementary visual function
What is the Neuropathology for Dorsal simultagnosia?
it is damage to the parietal lobe and dorsal stream
what is Ventral simultagnosia?
it is the Failure of object recognition despite being able to see multiple objects due to complex perceptual impairment in ventral stream
what is Associative agnosia?
- Failure of object recognition due to a higher order complex perceptual impairment
- Pressed elementary visual function and Seemingly normal copying
- Caused by damage to bilateral occipital-temporal cortex
What is aphasia
A language disorder
What is brooks aphasia
when your not Able to say what your thinking and it occurs in the frontal lobe
what’s neural implementation?
- Sensory organs absorb energy then converts it into a neural signal
- Energy is transduced into a neural signal
- The neural signal is sent throughout the brain where further processing takes place
name the different parts of the eye?
outer layer = cornea
middle layer =choroid and retina
inner layer = vitreous humour, iris, pupil, lens
what’s the lens property of accommodation?
means it is attached to muscles to change shape
what does the retina contain?
photoreceptors, ganglion cells and bipolar cells
what are the retinal ganglion cells?
Has 1 million fibres going out of the eye to form the optic nerve and Axons in the ganglion cells emerge from the eye forming the blind spot. If something is in your blind spot it will disappear from view
what do photoreceptors do?
-Contain pigment that takes electromagnetic energy from outside world and converts it into a neural signal then transmit information from the bipolar cell to the ganglion cell.
what degree is most peoples blindspot?
18 degrees to one side
how many rods and cones do we have, what do they do and where are they located?
rods= 120 million. they are active at night and are located in the periphery cones = 7 million, they work in light processing colour in high resoloution and are located in the fovea
what’s the fovea ?
area in the centre of your retina that contains desalt packed cones. it is where your central vision is?
how does information travel through your eye?
Pupil varies in size to allow light into eye -> light focuses on retina ->ganglion cells -> through bipolar cell layer -> photoreceptors turn light into electrical signals -> bipolar cell -ganglion cell ->optic nerve
how does visual information travel from visual information to brain?
Eyes -> lateral geniculate nucleus in subcortex -> V1/primary visual cortex in occipital lobe -> breaks off into tow streams, dorsal and visual
What did Mishkin and underbidder 1982 investigate and discover ?
investigated where information flows after the occipital lobe by doing an object and landmark discrimination task . They found that it travels down two streams to the parietal lobe (what) and temporal lobe (where).
where is visual information processed ?
Right visual field is processed in the left area of the brain vice versa
where does information flow in the auditory system?
ears -> sub cortex -> medical geniculate nucleus
what’s a receptive field?
the area of the retina which when stimulated by light causes a change in the neural activity of the cell
What’s the point of center-surround architecture?
- Enhances contrast – makes it easier for visual system to process
- E.g Brightness contrast. Precive that a square may be darker due to background when in reality they are the same colour
what do retinal ganglion cells like to look at?
spots of light
what did patient DB suffer from and what is it?
blindsight which is when you have damage to v1 primary visual cortex in the occipital lobe. Blindsight impairs the ability to see an object but you’re able to locate and respond to the visual stimuli. Able to do this because information by passes v1
v1=
primary visual cortex
what are the dorsal and ventral streams?
dorsal = where ventral = what
what’s Retinotopically topic mapping?
when cells in V1 look at a specific part of the visual field through point to point representation.
what happens if there is damage to the cells in v1 used for Retino topic mapping?
will cause a peppery mask as if there’s damage to cells in v1 it will cause blindspots in your visual field. That blindspot is called stomata. If there is damage to a lot of little cells in v1 then it will cause a peppery mask
what’s the apperceptive agnosia conts?
that apperceptive agnosia may be due to the peppery mask hypothesis. multiple blindspots will make it hard to recognise an object
Occipital lobe damage
- Blindsight
- Blindness
- Apperceptive agnosia
what system is the occipital lobe?
visual
Temporal lobe – superior temporal gyrus damage
- Auditory region – deafness
- deafness
- Wernicke’s aphasia
- Auditory agnosia
Damage to middle/inferior temporal gyrus
- Achromatopsia
- Akientatopsia
- Ventral simultanagnosia
- Associative agnosia
Damage to right medial temporal lobe
- Can copy
- Visual memeory is impaired
Damage to left medial temporal lobe
- Hearing is ok
- Verbal memory is impaired
Parietal lobe general damage
Impairments in: -Control of movement -Guiding movements to a point in space -Abstract concepts -Directing attention -Dorsal sultagnosia Overall: -in processing spacial information
parietal lobe left damage
- Agraphia
- Acalculia
- Right/Left Confusion
- Dyslexia
- Difficulty in drawing detail
Parietal lobe right damage
- Difficulty in recognising unfamiliar angles of objects
- Difficulty in drawing overall shape
- Contralateral Neglect
What is the primary use of the parietal lobes?
-Processing spacial information
Contralateral neglect is >
- Cannot comprehend a left half to objects
- Neglect everything to the left
- Test: Line and letter cancellation
Contralateral neglect is >
- Cannot comprehend a left half to objects
- Neglect everything to the left
- Test: Line and letter cancellation
Prefrontal cortex damage
- IQ
- Loss of divergent thinking – design and word fluency test
- Failures in response inhibition
- Failures to switch out of a pattern - Wisconsin Card
- Mimicry of actions
- Utilization behaviour
- Changes in personality - Phineas Gage
- Impairments in response inhibition cont – stroop interference test
- Imitation behaviour – environmental dependency syndrome
- Brocsaphasia
Define bottom up theory
- Brain breaks down info and rebuilds it later
Define top down theory
-what your mind expects to see is identified first and then information is expected to match that
what is the opponent process theory?
- That each cell is programmed to fire at one colour and have an opposite that they switch off at
- Blue/yellow
- Red/green
- Black/white
what is the Young-Helmholtz trichomatic theory?
-That different cones see in different colour
What is a problem with the Young-Helmholtz trichomatic theory?
- Cololur blindess occurs in pairs or you get coloured alter effects
what are binocular cues?
retinal disparity and convergence
What is localization of function?
-Localisation of function is the idea that secific behaviours are localised to specific parts of the brain
What is lateral inhibition
-Is the phenomenon in which a neurosn response to a stimulus is inhibited by neighbouring neuron
what’s wernikies aphasia?
problem with auditory comprehension
damage to superior temporal gyrus
can’t examplian the meaning of words etc
what focuses light on the retina
cornea and lens
what’s the order of information entering the ears
tympanic membrane, occicles, oval window, hair cells
