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113 Cards in this Set
- Front
- Back
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Optic nerve, optic chiasm vs optic tract |
Optic nerve: prior to chiasm Optic chiasm: where the two optic nerves meet Optic tract: after the optic chiasm |
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Anatomy of the occipital lobes (medial surface + ventral surface) |
Medial surface: -Parieto-occipital surface -Calcarine sulcus
Ventral surface: -Lingual gyrus (V2 and VP) -Fusiform gyrus (V4) |
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Calcarine sulcus |
Divides upper and lower part of our visual field |
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Lingual gyrus |
--bumpy landmark --contribute to area V2 (more specialized than V4 etc.) |
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How is V1 heterogenous? |
Made up of blobs and interblobs 1. Blobs are sensitive to colour perception 2. Interblobs are sensitive to orientation/motion |
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How is V2 heterogenous? |
Thick -Motion and form perception
Thin -Colour perception |
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How does colour vision of occipital cortex help? |
Used in detection of movement, depth and position |
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Three places info can go after v1/v2 |
1. Dorsal stream 2. Ventral stream 3. STS |
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What part of occipital lobe does colour? |
Fusiform gyrus (v4) |
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Where does the info from blobs, inter blobs and V1&V2 go? |
Blobs--> Area V4 COLOUR Interblobs--> Area v5/mt motion V1&V2--> area v3 (shape of objects in motion/dynamic form) |
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What percentage of monkey brain are made up of vision related areas? vs somatosensory and auditory |
55% vs. 11% somatosensory and 3% auditory |
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Five categories of vision |
1. Vision for Action 2. Action for vision 3. Visual recognition 4. Visual space 5. Visual attention |
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Top down |
--A bunch of parts to put together a story --Puzzle w/ multiple parts, connecting one part of the puzzle to another --Frontal lobes are contributing to how much information and how you are --Not always driven by stimulus --Action for vision (cognitive component) |
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Bottom up |
--Object In your environment and you reach out and grab it --Almost reflexive --Reaching and ducking --Driven by stimulus |
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Vision for action |
-Req'd to direct specific movements -Fingers will form a certain form to pick it up -Sensitive for movement -Function of the parietal visual areas in the dorsal stream (Recall dorsal stream is for visual guidance |
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Action for vision |
-Selectively attends to a certain object or a part of an object -Scan the right side of peoples faces more than the left (using the right side of the visual field) -Deficits in visual perception -People make eye movements when asked to visualize and rotate objects (look at left side) |
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Visual space + Locations in space (2) |
Parietal (and temporal lobes) -Spatial location 1. Relative to the individual (egocentric space) 2. Relative to one another (allocentric space) -Required for memory of objects |
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Visual attention |
Required for guidance of movements (in the parietal lobe) and for object recognition (in the temporal lobe) |
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Action for vision or vision for action is top down? |
Action for vision |
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Visual recognition |
-Temporal lobes -Object recognition -Ventral stream |
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Dynamic form |
-Object that is not moving (lateral or up) It may still be changing -Label may be independent of orientation -Form changes like rotating on a disc etc. -Image on retina changes but we know it’s the same object |
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Imaging studies of dorsal and ventral streams |
1. First task: subjects indicated which of two faces was identical with a sample face
--RESULTS: Activation of temporal regions for facial stimuli
2. Second task: The subjects were asked to identify which of two stimuli has a dot of a square in the same location as in a sample --RESULTS: Activation of posterior parietal region for location |
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Monocular blindness |
-Results in damage in retina, or the optic nerve |
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Bitemporal hemianopia |
-Temporal=sides -Loss of vision of both temporal fields -Lesion to optic chiasm |
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Right nasal hemianopia |
-Lesion in the side of the optic chiasm -Usually it’s the right lateral then it would be right nasal |
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Homonymous hemianopia |
-Blindness of entire field (either left or right) -Damage to LGN, V1 or optic tract |
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Quadrantanopia |
-One quad of entire field on both eyes -Occipital lobe damage |
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Mascular sparing |
-Damage to the occipital cortex -Small non- blind spot in origin of both blinded slide region |
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Scatomas |
-Blindspots that are caused by Small lesions to the occipital lobe -Usually unaware of them because of nystagmus (constant motion) -Found by TRICKING visual system |
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CAUSE: Occipital lesion, angioma in the right calcarine fissure
EFFECT: |
V1 DAMAGE AND BLINDSIGHT -Hemianopia -Cortical blindness ----Report of awareness to objects but not seeing them |
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Can the patient above ever detect legitimate movement? |
Yes, when stimulus is moving vigorously enough |
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CAUSE: Vascular abnormality which produced a bilateral posterior damage
EFFECT: |
-Loss of movement vision (as soon as a stimulus started to move the ability to see the object was gone) -Unable to intercept moving objects using her hand (tactile contact=unable to interpret)
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CAUSE: Concussion causing V4 damage and loss of colour vision
EFFECT: |
-Had amazing acuity after accident but loss of colour vision specifically in the occipital cortex |
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CAUSE: Electrocuted resulting in caridac arrest and ischemia
EFFECT: |
-Virtually blind although he could detect presence of absence of light -He was still able to identify and name colours the exact same of imagined objects (usually what people can't do after years) -Had activation in areas V1 and V2 in response to coloured stimuli |
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CAUSE: Carbon monoxide poisoning resulting in occipital damage and visual agnosia
EFFECT: |
OCCIPITAL DAMAGE AND VISUAL AGNOSIA
-Visual FORM agnosia --Severe inability to recognize line drawings of objects --Can see them and name them in person, can't name them when drawn although she can draw them from memory and cannot copy line drawings --She could recognize shapes and lines to move her visual accordingly (dorsal) but could not use the same visual information to recognize and identify the same objects (ventral) |
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CAUSE: Bilateral hemmorrhages in the occipitoparietal regions
EFFECT: |
Posterior Parietal damage and visuomotor guidance
-Optic ataxia ---Deficit in visually guided hand movements
-Had baliant's syndrome: where she had disordered control of her gaze, impairment in visual attention and optic ataxia
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CAUSE: right occipitotemporal lesion associated with left upper quadrantopia that extends into lower quad
EFFECT: |
Deficit in higher-level visual processes
-Couldn't identify faces and had difficulty understanding handwriting -Could identify lip-reading etc. |
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CAUSE: left occipitotemporal lesion with right hemianopia
EFFECT: |
Deficit in higher-level visual processes
-She had greater difficulty reading (Alexia) and was unable to name colours even though she could discriminate them -Could recognize faces but couldn't do lip reading |
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Object agnosia (2) |
1. Apperceptive agnosia 2. Associative agnosia |
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Apperceptive agnosia |
-Unable to copy objects (form) -Acuity, colour and motor stays the same -Simultagnosia (if two are placed, can't identify) -RESULTS FROM BILATERAL DAMAGE TO THE LATERAL PARTS OF OCCIPITAL LOBE -Effects ventral stream, could be do to carbon monoxide which causes neuronal death |
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Associative agnosia |
-Can preceieve them but not identify them -Results from lesions to anterior temporal lobes -Effects ventral -Can copy but can't identify ''Higher cognitive level of processing w/ memory |
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Prosopagnosia |
--Can't recognize any previously known faces including their own --Recognize face by face information such as birthmark etc. --Usually form bilateral damage w/ damage centered in the region below the calcarine fissue at the temporal junction (aka bilateral but assymetrical) |
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Alexia |
-Inability to read -Results from damage to left fusiform and lingual areas (both hemispheres matter but only left can put letters together to find words) |
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Two forms of alexia |
1. Form of object agnosia --Inability to construct perceptual wholes from parts 2. Form of associative agnosia --Word memory is damaged or inacessible --Problem w/ memory |
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Anatomy of parietal lobes |
Anterior: central Posterior: parieto-occipital Dorsal: cingulate gyrus Ventral: lateral/sylvian |
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Precentral gyrus
postcentral gyrus |
motor behaviour
sensory homunculus |
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What makes up the inferior parietal lobe? |
Supramarginal gyrus and angular gyrus |
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What makes up the anterior zones of parietal lobe? What is the anterior zone for? |
SOMATOSENSORY Anterior zones = Broadmann's Areas 1,2,3 (postcentral gyrus) & 43(parietal operculum) |
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What makes up the posterior zones of parietal lobe? What is the anterior zone for? |
5, 7 (superior parietal lobe) 39 (angular gyrus) & 40 (supramarginal gyrus) * Vision based function |
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Why does posterior parietal lobe differences in monkeys and humans make sense? |
We have different symptoms with damage because they don't have as well developed areas 39 and 40 (inferior) |
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What are the parts of von Economo's sytoarchitechtonic region? |
PE, PG, PF --All associated w/ vision because all in posterior parietal |
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What is so special about PG? |
Thought to be where STS is --Polymodal cells in PG (respond to both vision and somatosensory) --Increased in size over time --Very asymmetrical (larger on right than left) --Left STS/PG bigger in humans than in monkeys which explains why we see different symptoms when lesions in left occur |
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Saccade |
-Series of involuntary, abrupt and rapid small movements of jerks made by eyes simultaneously in changing the point of fixation |
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Anterior parietal cortex connections |
Projections from the primary sensory cortex 1. area PE (area 5) which is used in tactile recognition function 2. motor areas like primary motor cortex (Area 4) 3. supplementary motor and premotor regions (Area 6) |
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Connections of the parietal lobes |
PE (somatosensory) PF PG |
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PE What does it do and where does it receive input from? |
--PLAYS A ROLE IN GUIDING MOVEMENT BY PROVIDING INFORMAITON ABOUT LIMB POSITION -Input from somatosensory strip (primary somatos)
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PE where does output go to? |
Primary motor cortex (Area 4) , supp motor cortex, premotor (area 6 &8) and PF |
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Where does PF get input from? |
Somatosensory, primary motor cortex, premotor cortex, and PG |
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Area PG; where does it receive info from? |
-Recieves info from complex connections like visual, somesthetic (skin sensations), proprioceptive (internal), auditory, vestibular (movement), oculomotor and cingulate connections |
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What does PG have a role in? |
Parieto-temporo-occiptial crossroads -Part of dorsal stream -Have a role in controlling spatially guided behaviour w/ respect to visual and tactile information |
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Cingulate cortex |
* Thought to guide a lot of our motivation
* Motivation: what makes us engage in a particular act over others * Has to do with creating a hierarchy of what you're going to engage in * Part of your motivation has to do with collecting information about internal & external states of the environment |
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Theory of anterior zone and posterior zone function |
Anterior -Process somatic sensations and perceptions
Posterior -Integrate information from vision with somatosensory information and movement -EGOCENTRIC |
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Spatial information can be used in |
1. Object recognition 2. Guidance of movement |
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Explain object recognition |
-Viewer centered object identification ---Deteremines the location, orientation and motion at all times even though we're always moving |
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Explain guidance of movement |
-Sensitive eye movements (when stimuli is for reward of moving towards you) -Posterior parietal cortex |
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Monkey experiment |
TWO INTERESTING CHARACTERTISTICS OF THOSE WAVES OF MONKEYS 1. If a subject is asked to pay attention to a particular spot in one visual field, the ERP is largest when the stimulus is presented there2. Large parietal response between 100 and 200 ms before eye movements
EVIDENCE FOR THE FACT THAT PARIETAL IS USED IN GUIDANCE OF MOVEMENT AND STIMULI (OBJECT RECOGNITION) |
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Sensorimotor transformation |
-When we move toward objects we must integrate the movements of different body parts with the sensory feedback of what movements are actually being made and the plans to make the movements -As we move, the locations of our body parts are continually changing and must constantly be updated so that we can make future movements smoothly |
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Movement planning |
-Area PRR is used in movement planning -Used to plan desired goal of movement not what it takes to actually do the movement |
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Monkey experiment w/ limb and prosthetics PART 1 |
PART 1: Monkeys were first trained to make a series of reaches to touch different locations on a computer screen ''REACH TRIAL'' --Monkeys are trained to touch a small central green cue and to look at a red fixation point --A large green cue is flashed in opposite corner and the monkeys are rewarded if they reach to the target after a 1500-ms memory period |
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Monkey experiment w/ limb and prosthetics PART 2 |
Monkeys then were instructed with a briefly flashed cue to plan to execute a reach to different locations but without making a movement ''BRAIN CONTROL TRIAL'' --Cellular activity was compared with activity associated with actual movements to the requested target and if it was the same they were rewarded (had to do this b/c couldn't tell them to think about a movement) |
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Route knowledge |
nternal list of ''cognitive spatial map'' on how to get places and the things of what we must do at each location in order to get to final destination |
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What parts of brain does spatial knowledge use? |
MPR (parietal region ventral to PRR) and posterior cingulate cortex and neurons in dorsal visual stream |
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What happens when they trained monkeys to perform navigation tasks in virtual environment? |
--3/4 of the cells in MPR showed responses associated w/ a specific movement at a specific location --Same movement at diff location didn't show same response --Therefore shows that neurons MPR show specific responses to specific locations --If MPR neurons were inactivated then they would become lost |
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Three symptoms of parietal lesions that don't make sense with parietal and its common ''visuomotor'' control centre |
1. Language 2. Movement sequencing 3. Arithmetic |
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Language |
-Words have spatial organization EX. ''tap'' vs ''pat'' physically different EX. ''my son's wife'' vs ''my wife's son'' ----QUASI SPATIAL which means that identical words but different meaning
--PEOPLE W/ DAMAGE CAN'T UNDERSTAND |
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Movement sequencing |
-Individual elements of the movement have spatial organization ----Cannot copy movements |
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Problems w/ arithmetic |
Acalculia --Spatial w/ carrying column etc. |
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Lesions to postcentral gyrus of parietal lobe produce |
-Abnormally high sensory thresholds -Impaired position sense -Deficits in stereognosis -Afferent paresis |
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Stereognosis
Afferent paraesis |
-Tactile perception
-Clumsy finger movements due to lack of feed back about finger position |
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Somatoperceptual disorders |
--Just b/c you have normal somatosensory thresholds doesn't mean that there can't be other somatosensory disorders |
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Asterognosis |
INABILITY TO RECOGNIZE AN OBJECT BY TOUCH |
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How to test for asterognosis |
1. Object on palm of blindfolded
Subjects or the subjects are told To handle shapes 2. The task is to match the original shape w/ tactile information |
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Simultaneous extinction |
-Two stimuli are applied at same time to opposite sides of body and failture to report a stimulus is called extinction |
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Where is damage associated w/ extinction? |
-Damage to somatic secondary cortex (PE and PF) |
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Examples w/ coin and fork |
Same stimuli, only one is need Diff stimuli, both are seen Same but a lil different, only one is seen |
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Asomatognosia |
--The loss of knowledge of sense of one's own body and bodily condition --May reflect one or both sides of body although usually it is the left side due to lesions in the righ |
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Types of asomatognosia |
1. Anosognosia --Unawareness or denial of illness 2. Anosodiaphoria --Indifference to illness 3. Asymbolia for pain --Absence of normal reactions to pain |
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Autopagnosia |
-Lesion to left |
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Type of autopagnosia |
Finger agnosia --Unable to point fingers or count (correlation w/ this and acalculia |
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Baliant's syndrome |
-Full visual fields, recognize objects name objects, label pictures, label colours -Can't fixate on a visual stimulus (will look away) -Neglect of objects (Simultagnosia) -Optic ataxia (deficit of visually guided movements) |
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Two parts of recovery for contralateral neglect |
1. Allesthesia --Begin to respond to the neglected stimuli as if they were on the working side 2. Simultaenous extinction -The person responds to the things on the other side unless presented at the same time |
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What causes contralateral neglect? |
-Lesion most often to the right inferior parietal lobe (angular gyrus + intraparietal sulcus) -Could also be lesions to frontal lobe and cingulate cortex
-Claim it could be defect in sensation or perception also in attention or orietnation |
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Amorphsynthesis |
-Disruption in sensation or perception -Right parietal lesion makes the spatial properties of stimuli to become disturbed -Left side can only attend to left visual field? |
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DEFECTIVE ATTENTION OR ORIENTATION |
-Defect in orienting to stimuli -The defect results from the disruption of a system whose function is to ''arouse'' the person when new sensory stimulation is present |
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Symptoms of posterior parietal lobe damage |
-Object recognition ----After right parietal lobe lesions parries are poor at recognizing objects in unfamiliar views (not problem w/ object but when it's perception is changed) --Deficit in the inferior parietal lobule |
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Gerstmann syndrome |
-Finger agnosia usually is assocaited with right-left confusion, agraphia (inability to write) and acalculia -Lesion in angular gyrus |
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Left parietal symptoms |
1. Disturbed language 2. Apraxia 3. Finger agnosia 4. Dyscalculia 5. Recell low digit span 6. Right-left discrimination is poor |
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Explain language function disturbed
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-Unable to write (agraphia), serious difficulties in reading (dyslexia) and spoke slowly making many grammar errors (dysphasia)
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Apraxia and 2 types |
-Disorder of movement in which the loss of skill movement is not caused by weakness by an inability to move and abnormal muscle tone 1. Ideomotor Apraxia -Patients are unable to copy movements IN ORDER -Left posterior lesions -We know it is a left posterior lesion because they cannot form these serial arm-movement tests but people with right posterior lesions can 2. Constructional apraxia -Cannot assemble a puzzle, facial expressions etc. -Either parietal lobe lesion |
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How to test for ideomotor apraxia? |
Serial arm-movement copying test |
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How to test for constructional apraxia? |
-Asking to draw a picture -Facial movement |
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Kimora Box test |
Movement series 1. Pushing with index finger 2. Pulling handle 3. Pressing bar down with thumb |
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Drawing deficits, with what lesion is it worse? |
--Worse when damage is to the right --Not always true b/c found people with apraxia and aphasia did worse because can't either do movements of drawing or can't comprehend the words |
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Spatial attention |
-Disengagement: allowing attention to shift from one thing to another --Must reset when choosing to shift from selective attention |
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Test for function somatosensory threshold |
TEST #1: TWO POINT DISCRIMINATION -Requires a blindfolded subject to report whether he or she felt one or two points touch the skin and usually is very large like 3 cm and then it gets smaller and smaller until they can't feel the two points --At one point do you start to find feeling that two pressure points are as one on the arm while blindfolded, usually on the arm or the back HEALTHY: Intact at some certain point where they start to think two point of pressures as one |
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Test for function tactile form recognition |
TEST #1: Seguin-Goddard -Blindfolded and feel around different types of form and match them with an identical set of forms in order to make a comparison -Asked to draw form board from memory -Sensitive to lesions in PG |
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Test for contralateral neglect |
TEST #1: Line bisection -Asked to mark the middle of each set of 20 lines -Each line is different length and located at different position of page -People w/ neglect ignore left side |
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Test for visual perception |
TEST #1: Gollin Incomplete figures TEST #2: Mooney Closure -Both tests, a series of incomplete representations of faces or objects are presented and the subject must combine the elements to form ''gestalt'' and identify the picture -Sensitive to damage at the right parieto-temporal junction |
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Test for spatial regions |
TEST #1: Right and Left differentiation -Hands, feet, ears etc. are presented in a different orientation (upside down etc.) and asked if it is a left or right body part -Asked to touch your right ear with your left hand etc. -Both tests are very sensitive to left-parietal lobe damage and show damage is the left and right sides are offset |
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Test for language #1 speech comprehension |
TEST #1: SPEECH COMPRHENSION Token test -20 tokens, 4 shapes in each 5 colours -Simple tasks like touch white to touch this with this and this -Also asked to read tasks and follow them out which shows temporal speech related cortex TEST (1) SAYS: Give token and given instructions person has to follow speech instructions and then follow along. (take this quarter and put it in your pocket) Speech comprehension method is hard to see if it's a problem with understand speech or a motor problem of putting the quarter in your pocket |
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Test for language #2 reading comprehension |
-20 tokens, 4 shapes in each 5 colours -Simple tasks like touch white to touch this with this and this -Also asked to read tasks and follow them out which shows temporal speech related cortex
TEST (2) SAYS: Reading instructions instead of speech; same problem w/ motor and trying to differentiate |
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Test for apraxia |
TEST #1: Kimura Box -Required to make a consecutive movements of pushing a button with the index finger and pulling a handle with form fingers and pressing a bar with the thumb -Apraxics perform very poorly on this test and many of them are unable to do the simple movements with extensive practice |
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Explain the visuospatial functions of STS
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--Part of multimodalcortex and uses polysensory neurons --Polysensory neurons: neurons that are responsive to both visualand auditory or both and somatosensory input --Connects w/ infofrom parietal lobe and temporal lobe due to interactions with dorsal andventral stream--Combines the whatand the where to frontalcontent --Respond tobiological information (alive or not) which Is interesting b/c usually we thinkthat that would happen in the frontal lobes
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