Occipital and Parietal Lobes Org and Function Flashcards
Functions of Area V1
color perception
form and motion perception
Functions of Area V2
more detailed/ integrated color, form, and motion perception
Functions of Area V4
primarily involved in color perception (fine-tuned)
Dorsal Stream (visual)
the “where” pathway
sends info to the parietal lobe
visual info to locate objects, detect movement, orient attention, and coordinate for action/ grasping
Ventral Stream (visual)
the “what” pathway
Sends info to inferior temporal lobe
object perception and detection, process color and form
What is the STS stream?
Located in the parietal and temporal lobes
Neurons are responsive to both auditory and visual input
Interaction between the visual and dorsal streams
What is visual dysfunction?
Dysfunction in visual pathway before it reaches the occipital cortex will result in total loss of visual perception for the parcel of associated information
What is apperceptive agnosia?
Damage to bilateral lateral occipital lobes
Failure in object recognition but basic visual functions (acuity, color, motion) preserved
What is associative agnosia?
Damage to anterior temporal/association areas
Inability to recognize an object despite its apparent perception (e.g. Can copy a drawing, but cannot identify it)
What is prosopagnosia?
Face blindness
Damage to the fusiform gyrus
Inability to recognize faces (even own face)
What is pure alexia?
Damage to the splenic might of the corpus callousness and left visual cortex
Inability to read/ perceive letters/ words with intact speech, hearing and wiring
Somatosensory agnosias:
Asomatognosia: loss of sense of one’s own body, most commonly affects left side of body
Anosognosia: unawareness or denial of illness
Anosodiaphoria: indifference to illness
Asymbolia for pain: absence of normal reactions to pain such as withdrawal
Autopagnosia: finger agnosia
Usually results from left parietal cortex lesions
What is contralateral neglect?
Neglect for visual, auditory, and somesthetic stimulation on one side of the body or space
Lesion most often in the right inferior parietal lobe (left neglect)
What do right parietal lobe lesions sometimes impair?
Patients can be impaired at recognizing familiar objects in unfamiliar views
What is apraxia?
Movement disorder in which the loss of movement is not caused by weakness, inability to move, abnormal muscle tone, intellectual deterioration, poor comprehension, or other disorders of movement
What is Bálint’s Syndrome?
Bilateral damage to the occipito-parietal region
Simultagnosia: can’t perceive while visual field
Oculomotor apraxia: difficulty fixating eyes (gaze paralysis)
Optic apraxia / dysmetria: difficulty with hand-eye coordination
What is Gerstmann Syndrome?
Finger agnosia of fingers on either hand
Right-left confusion
Agraphia: inability to write
Acalculia: inability to do simple math problems
Disturbed language function
Results from a left parietal lobe lesion (angular gyrus)
What is spatial disorientation?
Distortions in spatial perception
Out of body experiences (imagine that they have more than one body, feel that they are occupying a space distant from their bodies, see people or objects that are not there)
What are some of the functions of the parietal lobes?
Anterior zones- process somatic sensations and perceptions
Posterior zones- integrate information from vision with somatosensory information for movement and spatial function, play significant role in mental imagery, especially object rotation and navigation through space
Functions also when no movement is required (concept of left and right, cognitive spatial maps in the brain, mental rotation of objects)
Other functions include arithmetic (more complex math requiring spatial manipulation) language (because words have spatial organization) and movement sequencing (individual elements of the movement have a spatial organization)
What are some somatoperceptual disorders?
Astereognosis: disorder of tactile perception (inability to recognize nature of an object by touch)
Simultaneous extinction: two stimuli applied simultaneously to opposite sides of the body, a failure to report a stimulus on one side is referred to as extinction
Numb touch: cannot feel stimuli and cannot feel touch, but can report the location of the touch, complete anesthesia on one side
What symptoms do lesions to the sensory strip (postcental gyrus) typically produce?
Abnormally high sensory thresholds
Impaired position sense
Deficits in stereognosis (or tactile perception)
Afferent paresis (clumsy finger movements due to lack of kinesthetic feedback about finger position)
What are some of the behavioral uses of spatial information?
Object recognition/ identification
Guidance of movement to objects
Sensorimotor transformation (perception of the body’s position relative to novelty being made and planned)
What are the subdivisions of the parietal cortex?
Postcentral gyrus (somatosensory cortex)
Superior parietal lobule (guides movement, info on limb position)
Parietal operculum
Supramarginal gyrus
Angular gyrus (input from somatosensory and visual areas)
