Exam 3 Flashcards
chapters 6-8
what is the What pathway?
The ventral stream
What does the ventral visual processing stream consist of?
Areas of the occipitotemporal and temporal regions that are devoted to the processing visual stimuli
Cells is the ventral visual system (what pathway) fire in response to what?
Relatively simple stimuli, but cells further along the stream fire to more complex, specific stimuli
what falls under the category of “simple stimuli” in the ventral visual system?
Orientation to lines and edges, color, shape, etc.
What falls under the category of “complex stimuli’ in the ventral visual system?
Faces and whole objects
what are the two trends noted in the ventral visual system?
1) cells early in the pathway fire to simple stimuli, and cells farther along in the pathway fire to complex stimuli
2) receptive fields become larger
What type of receptive field allows for the cell to respond to objects on he basis of their global shape (allows an object to be identified regardless of its size or where it is located in space)
large receptive field
what is the consequence of having a large receptive field?
Some information about an item’s position in space is lost
what does area V4 process?
Color processing as well as colors in different hues or lighting
Cells in the ventral processing stream are
often sensitive to _____, which aids object
recognition.
Color
damage in the ventral stream of the cortex leads to a deficit in…
Object recognition
Visual Agnosia definition
An inability to recognize objects in the visual modality that cannot be explained by other causes
True or false: Visual agnosia is modality specific
Yes! This mean that it manifests in only one of the senses (in this case, the visual sense)
What are the two types of visual agnosia?
Apperceptive and associative
Apperceptive agnoisa
- is a fundamental difficulty in forming a perception
-the data cannot be bound together to allow the person to to perceive a meaningful whole
Associative agnoisa
Basic visual information can be integrated to form a meaningful perceptive whole, but that particular whole cannot be linked to stored knowledge
What is the main difference between Apperceptive and associative agnoisa?
the type of visual information that can be processed
- Classic Apperceptive agnoisa can process crude visual information
- People with associative agnoisa can perceive much more detailed info than those with Apperceptive agnosia, which is proven by ther ability to match and copy items, and they can extract some information about general shape
Where is brain damage typically seen in patients with Apperceptive agnoisa?
Diffuse damage to the occipital lobe and surrounding areas
Where is damage typically seen for patients with associative agnoisa?
The occipitotemporal regions of both hemispheres and sub-adjacent white matter
What is Prosopragnosia?
(Agnoisa for faces)
A selective inability to recognize or differentiate faces
Where is damage found in prosopagnosia patients?
The ventral stream of the right hemisphere
where does damage for patients with visual agnosia of words occur?
The left hemisphere in the region known as the visual word form area
What percent of the population suffers from congenital prosopragnosia?
2%
What types of information can prosopagnosia patients determine?
- that a face is a face
- age
- gender
- facial expression/emotion
Category-specific deficit
The inability to recognize or identify a certain category of objects even though the ability to recognize other categories of items in that same modality is retained
Sparse coding
The theory that a small but specific group of cells responds to the presence of a given object
What is an extreme example of sparse coding? Is it thought to be right?
The grandmother cell theory; no
population coding
The theory that the pattern of activity across a large population of cells codes for individual objects
What is an extreme version of the idea of Population coding?
That every cell in the ventral stream is involved in coding for every object
What is used to study visual invariance?
Adaptation
Inversion effect
Phenomenon in which recognition is poorer when an object is turned upside down. Suggests that faces are processed as wholes, configurally
Conjunctive encoding
Assumes that features are explicitly conjoined, or linked together
Nonlocal binding
Assumes that a whole object is represented simply by the co-activation of units that represent the parts of the objet in particular locations
what are the two possible models of how individual features combined into whole shapes?
Conjunctive encoding and nonlocal binding
Fusiform face area (FFA)
Which exhibits a greater response to faces than to other objects
Parahippocampal place area (PPA)
Appears to process visual information related to placed in the local environment
Extrastriate body area (EBA)
Responds preferentially to images of human bodies and body parts, compared to various inanimate objects and object parts
What have researchers discovered about monkey face-specific cells?
They are distributed asymmetrically and are more evident in the right hemisphere
Double dissociation
A method for demonstrating that two mental processes can proceed independently of one another, and that they rely on different neural substrates
What did evidence from brain-damaged individuals, neuroimaging, and electrophysiology indicate that _____ are processed differently than other classes of objects
Faces
Which hemisphere plays a predominant role in face processing?
Right
What is the Superior Temporal Sulcus (STS) involved in processing?
Those features of the face that change, such as eye gaze and expression
Where is the Parahippocampal place area (PPA) located?
In a ventral cortical region bordering the hippocampus
What does the PPA typically respond to?
Strongly to visual scenes such as landscapes, rooms, houses, or streets
The ventral stream region in the left hemisphere appears to be responsive to visually presented _______.
Words
Multi-voxel pattern analysis
To examine the degree of activation in certain brain regions, as well as the pattern or mosaic of activation
the more similar visual items are, the more similar are their ______ of activity across the brain
Patterns
auditory agnosia
The inability to recognize sound
auditory agnosia usually manifests in one of three ways. What are these three ways?
- Verbal auditory agnosia
- Nonverbal auditory agnoisa
- Mixed auditory agnoisa
What is Verbal auditory agnoisa?
also known as Pure-word deafness
Words cannot be understood, although the ability to attach meaning to nonverbal sounds in intact.
Often complains that speech sounds like “an undifferentiated continuous humming noise without any rhythm”
nonverbal auditory agnoisa
Rarer than verbal auditory agnosia
The ability to attach meaning to a word in intact, but the ability to do so for nonverbal sounds is disrupted
Ex: cannot categorize a dog bark or a lawn mower
Mixed auditory agnoisa
the ability to attach meaning to both verbal and nonverbal sounds is affected, although the patients can determine whether two sounds are identical or different and whether one sound is louder than the other
Somatosensory/Tactile agnoisa
A condition in which a person is unable to recognize an item by touch
What are the two types of somatosensory agnosia that have been proposed?
1) he affected person has the inability to use tactile information to create a percept
2) the percept is more or less intact but cannot be associated with meaning (tactile asymbolia)
What is tactile asymbolia
The tactile information cannot be linked to its symbolic meaning
In everyday life, we often receive _________ cues to recognition simultaneously from multiple modalities
Parallel
What region is known to be important to the visual perception of objects?
lateral occipital complex (LOC)
Voices of familiar people have been shown to activate which brain area more than the voices of unfamiliar people?
FFA
What stream is the dorsal pathway?
The “where”
the dorsal visual processing stream projects from where to where?
primary visual areas to parietal regions
What is another name for the Primary somatosensory area?
the Anterior Parietal cortex
which lobe is primarily concerned with somatosensory representations?
the anterior parietal lobe
Which cortex is multisensory and is crucial in many aspects of spatial cognition?
the posterior parietal cortex (PPC)
what are the superior parietal lobule and the inferior parietal lobule separated by?
the intraparietal sulcus
Area MT(middle temporal V5) and MST (he medial superior temporal area) contribute to the understanding of what?
motion
the primary visual cortex and the somatosensory cortex provide information about what?
the body in space
What part of Einstein’s brain was larger and attributed to his increased ability to do math and physics?
the parietal cortex
What are the functions of the three separate pathways that project from the dorsal stream to other areas?
- spatial working memory
- visually guided action
- Spatial navigation
What is the pathway that is concerned with supporting spatial working memory?
connects the parietal cortex to the prefrontal cortex
What pathway is concerned with supporting visually guided actions such as reaching and grasping?
connects the parietal cortex to the premotor cortex
What pathway is concerned with supporting spatial navigation, such as wayfinding around an environment?
connected the parietal cortex to the medial temporal cortex (including hippocampus and parahippocampal cortex)
why are cells in the parietal areas not good at detecting the visual properties of objects?
because they are not sensitive to form or color
Cells in the posterior parietal cortex appear to be responsive to a combination of the retinal location of the visual stimulus AND the position of the animal’s eyes or head. This allows the creation of what in the brain?
A stable spatial map of the world
In patients with parietal damage, is it more difficult for them to determine if an object is facing right or left or is it more difficult to distinguish up or down?
it is harder for them to distinguish left facing from right facing
they are good at up/down distinction, as well as if an object is presented at different angles
which plane does depth perception help us localize items in?
near-far plane
Binocular Disparity
discrepancy between the images seen by two eyes that is a cue to depth
Cells in which cortex are sensitive to different amounts of binocular disparity?
primary visual cortex
what two cue types are integrated in area MT to code for depth?
binocular disparity and motion parallax
Is motion parallax a binocular or monocular depth cue?
monocular
what is the gist of motion parallax?
near objects move slower and farther objects move faster
egocentric reference frames
specify an object’s location in relation to some aspect of the self
Allocentric reference frame
specify an object’s location in relation to other objects
Damage to which parietal lobe is most often associated with egocentric neglect?
right parietal lobe
Object-centered neglect
patient ignores half of an object regardless of how that object is displayed or oriented
What are the names of the three different realms?
- Personal space
- Peripersonal space
- Extrapersonal space
Personal space
referring to spatial position on the body
Peripersonal space
referring to the spatial realm within arm’s reach, or near space
Extrapersonal space
far space, referring to the area beyond arm’s reach
Categorical spatial relations
specify the position of one location relative to another in dichotomous categorical terms (above vs below, top vs bottom, left vs right)
Coordinate (or metric) spatial relations
specify the distance between two locations
which hemisphere is specialized for determining categorical spatial relations?
left
which hemisphere is specialized for computing coordinate (metric) spatial relationships?
right
corollary discharge
a signal to visual areas about the upcoming eye movements
What is one important function of the dorsal stream?
to participate in sensory-motor translation-transforming sensory representations into action patterns
Constructional praxis
the ability to motorically produce or manipulate items so that they have a particular spatial relationship
What is a critical element of constructional praxis?
spatial perception
Optic ataxia
a type of spatial deficit seen in patients with parietal lobe damage. these patients have difficulty with visually guided reaching and may fail to take obstacles into account when reaching for an object
true or false: optic ataxia appears to be doubly dissociable from visual agnosia.
true
which stream is important in supporting both visually guided reaching and grasping movements?
the dorsal stream
Egocentric disorientation
the inability to represent the location of objects in relationship to the self
landmark agnosia
is more like an object-recognition deficit than a true spatial deficit, although it does disrupt wayfinding ability
anterograde disorientation
a patient is unable to construct new representations of environments due to parahippocampal damage
heading disorientation
a patient is unable to recognize landmarks and understand relations between locations in space due to retrosplenial cortex damage
(has trouble knowing his own orientation in a familiar or unfamiliar environment)
Which hemisphere plays a leading role in speech production (at least for right-handers)?
the left
Aphasia
a disruption in the ability to process or produce language
Wada technique almost always leads to speech arrest after injection into which hemisphere?
left
in split-brain patients, only the left hemisphere can do what?
produce speech output
Broca’s aphasia
damage to this region results in a difficulty with speech output, but can comprehend just fine
what does lesioning anterior to the central fissure cause?
Broca’s aphasia
Wernicke’s aphasia
characterized by disrupted speech comprehension, but speech output is fluent
What are the words of patients with Wernicke’s aphasia called?
Word salad
semantic paraphasia
substitute a word with a similar meaning to the intended word
phonemic paraphasia
substitute a word with a similar sound to the intended word
neologisms
made-up words that follow the rules for combining sounds in the language, yet are not real words
paraphasias
an inability to link sound images to meaning
Anterior regions of the left hemisphere are specialized for ____ _____
speech output
Posterior regions of the left hemisphere are specialized for ____ __________
speech comprehension
conduction aphasia
the inability to repeat what was just heard (although language comprehension and speech production are intact)
Damage to which white matter tract causes conduction aphasia?
the arcuate fasciculus
global aphasia
the inability to comprehend or produce language
What is the classic three-part model of 19th century aphasiologists/(Classical Neurological Perspective)
- language input center
- language output center
- a critical neural pathway connecting the two
What three parts do psycholinguists divide language into?
- phonology (rules of sound combination)
- syntax (rules of grammar)
- semantics (meaning of language)
Phoneme
considered the smallest unit of sound that can signal meaning
Phonology in Broca’s aphasia
may have difficulty producing both the correct phonetic and phonemic representations of speech sounds
Phonology in Wernicke’s aphasia
may have difficulty producing the correct phoneme (meaning), but do not have phonetic issues (sound)
What is N400?
- it occurs about 400ms after the event occurs
- found in the posterior cortex (left temporal cortex)
- it is sensitive to Semantic anomalies
what is P600?
- it occurs about 600ms after the event occurs
- it is in bot the posterior and anterior cortices
- it is sensitive to Syntactic anomalies
