Chapter 6: Object recognition Flashcards
What is agnosia?
A neurological syndrome in which disturbances of perceptual recognition cannot be attributed to impairments in basic sensory processes. Agnosia can be restricted to a single modality, such as vision or audition.
What is alexia and what are the 3 types of alexia?
A neurological syndrome in which the ability to read is disrupted.
Alexia is frequently referred to as acquired alexia to indicate that it results from a neurological disturbance such as a stroke, usually including the occipitoparietal region of the left hemisphere.
In contrast, developmental alexia (dyslexia) refers to problems in reading that are apparent during childhood development.
The phrases acquired alexia and developmental alexia are commonly used to indicate that reading is abnormal, either from a neurological disturbance or as part of development.
What is apperceptive visual agnosia?
A form of agnosia associated with deficits in the operation of higher-level perceptual analyses. A patient with apperceptive agnosia may recognize an object when seen from a typical viewpoint. But if the orientation is unusual, or the object is occluded by shadows, recognition deteriorates.
What is associative visual agnosia?
A form of agnosia associated with deficits in the ability to link perceptual representations with long-term knowledge of the percepts.
For example, the patient may be able to identify that two pictures are of the same object, yet fail to demonstrate an understanding of what the object is used for or where it is likely to be found.
What is the dorsal or occipitoparietal stream?
Also called the occipitoparietal stream. A processing pathway for visual stimuli that is specialized for spatial perception (for determining where an object is) and for analyzing the spatial configuration between different objects in a scene.
What is the extrastriate body area (EBA)?
A functionally defined area in the lateral occipitotemporal cortex that shown a stronger response to images containing body parts relative to other animate and inanimate stimulus categories.
What is a functional near-infrared spectroscopy (fNIRS)?
A noninvasive neuroimaging technique that measures near-infrared light absorbance in oxygenated and deoxygenated hemoglobin, providing information about ongoing brain activity similar to functional MRI studies.
What is the fusiform body area (FBA)?
A functionally defined area in the lateral occipitotemporal cortex, adjacent to and partially overlapping the fusiform face area, that shows a stronger response to images containing body parts relative to other animate and inanimate stimulus categories.
What is the fusiform face area (FFA)?
A functionally defined area of the brain, located in the ventral surface of the temporal lobe in the fusiform gyrus, that responds to selective stimuli, such as faces.
What is a gnostic unit?
A small neuron or small set of neurons tuned for a specific percept. The concept of the gnostic unit is based on the idea that hierarchical models of perception imply that, at higher levels in the system, neurons become more selective in terms of what they respond to.
What is meant by holistic prosessing?
Perceptual analysis that emphasizes the overall shape of an object. Face perception has been hypothesized to be the best example of holistic processing, in that the recognition of an individual appears to reflect the composition of the person’s facial features rather than being based on the recognition of the individual features.
What is integrative visual agnosia?
A form of agnosia associated with deficits in the recognition of objects due to a failure to group and integrate the component parts into a coherent whole. Patients with this deficit can faithfully reproduce drawings of objects; however, their percept is of isolated, unconnected parts or contours.
What is the lateral occipital cortex (LOC)?
The region of the cerebral cortex that lies anterior to Brodmann area 6, along the lateral surface. This region has been implicated in various executive functions, such as working memory and response selection.
What is object consistency?
The ability to recognize invariant properties of an object across a wide range of viewing positions, illumination, and contexts. For example, although the size of the retinal image changes dramatically when a care recedes in the distance, our percept is that the car remains the same size. Similarly, we are able to recognize that an object is the same when seen from different perspectives.
What is optic ataxia?
A neurological syndrome in which the patient has great difficulty using visual information to guide her actions, even though she is unimpaired in her ability to recognize objects. Optic ataxia is associated with lesions of the frontal lobe.
