Agnosia

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The word agnosia comes from the Greek word gnosis, which means _____. Therefore, agnosia means the absence of ______.: The word agnosia comes from the greek word gnosis, which means KNOWLEDGE. Therefore, agnosia means the absence of KNOWLEDGE.
Define agnosia.: Agnosia is a disorder of recognition; the patient is unable to recogize the meaning of information conveyed within a given sensory domain from the external environment to the brain. This deficit occurs in only a single sensory modality and cannot be attributed to sensory defects, mental deterioration, nonfamiliarity, aphasic misnaming of the obejct, or impairment an in consciousness or attention.
What were the original terms used for visual agnosia?: Visual agnosi was called "mind blindness" or "psychic blindness."
Agnosia was first demonstrated in a _____ by _____ in 1881.: Agnosia was first demonstrated in a DOG by MUNK in 1881.
Who first coined the term agnosia?: Freud coined the term agnosia in 1891
Is agnosia a sensory/perceptual or memory related disturbance?: This has been the source of some debate. Proponents of both sides assume that the two processes are separable. Teuber argued that agnosia is an impairment of access to memory located at the interface between perception and memories. Bender and others argued that agnosia is a perceptial impariment or the result of dementia.
The most lasting distinction of agnosia types was proposed by ____ who differentiated ______ agnosia from _____ agnosia.: The most lasting distinction of agnosia types was proposed by LISSAUER (1890) who differentiated APPERCEPTIVE agnosia from ASSOCIATIVE agnosia.
What are the two types of agnosia and what is the distinction between them?: Apperceptive Agnosia - the damage is fairly early on in the recognition "assembly line," before perception is properly constructed - patients do not perceive objects normally, so they do not recognize them
Associative Agnosia - the fault is in the later stages of recognition; perception may be intact, but access to memory or meaning is not - "a normal percept stripped of its meaning" - Teuber
In what type of visual agnosia is a patient most likely to describe his/her vision as "blurred" or "foggy"?: apperceptive agnosia
In what type of visual agnosia is a patient unable to draw misidentified objects or match them to a sample?: apperceptive agnosia
In which type of agnosia is visual acuity intact, but visual recognition impaired?: associative agnosia
Which type of agnosia is often associated with right homonymous hemianopia?: associative agnosia
Which type of agnosia is relatively rare?: apperceptive agnosia
In which type of visual agnosia is a patient able to drawy pictures they can't recognize and match drawings/pictures to samples.: associative agnosia
Which type of agnosia is most likely to be observed inpatients recovering from cortical blindness?: apperceptive agnosia
Why is there now growing discontent with the apperceptive-associative distinction?: There is now growing discontent with the distinction, because recent research has suggested that patients with associative visual agnosia actually do have abnormal perceptual abilities.
Where are lesions typically located in apperceptive visual agnosia?: usually results from bilateral damage to the lateral parts of the occipital lobes
Where are lesions typically located in associative visual agnosia?: usually results from bilateral occipitotemporal lesions (often from PCA strokes)
What is prosopagnosia?: Prosopagnosia is an impairment in which patients cannot recognize familiar faces. They may identify the same people they cannot recognize by voice, dress, and/or mannerisms.
True or False? Prosopagnosia is limited to human faces.: False. Prosopagnosia is NOT limited to human faces (e.g., a dairy farmer would not be able to recognize his cows individually)
Where is the lesion typically located in prosopagnosia?: Prosopagnosia typically results from bilateral lesions of the occipitotemporal cortex and underlying white matter
True or False. If a unilateral lesion results in prosopagnosia, the lesion is located in the left hemisphere.: False. If a unilateral lesion results in prosopagnosia, the lesion is in the RIGHT hemisphere.
What is visual object agnosia?: The inability to recognize, name, or demonstrate the use of an object such as a pencil, chair, or clock; they are unable to recognize the general category to which an object belongs.
Occasionally a person with visual object agnosia is able to recognize an object if it is moved or rotated. This is called ____ ____ agnosia.: This is called STATIC VISUAL AGNOSIA.
Where is the lesion typically located in visual object agnosia?: visual object agnosia can result from either left unilateral or bilateral occipitotemporal regions (i.e., lingual, fusiform, parahippocampal gyri) and infarction in the cortex and underlying white matter of those areas
What is optic aphasia?: visually presented objects can be recognized by not named; however, auditory and tactile naming is intact; there is disagreement regarding whether this is a form of visual object agnosia or a separate entity
Name the three classes of color agnosia.: 1) central achromatopsia
2) color anomia
3) specific color aphasia
Define central achromatopsia.: Central achromatopsia is a loss of color vision due to CNS disease; patients often compalint of a gray or washed out look in the affected area.
Ture or False? In central achromatopsia, patients experience a complete loss of color vision.: False. Achromatopsia can be complete or it can be retricted to certain visual quadrants
True or False? In addition to losing color vision, patients with achromatopsia lose the ability to perceive form and shape?: False. Patients with achromatopsia are still able to perceive form and shape.
Achromatopsia often results from lesions in what brain region?: damage to the visual association cortex or subjacent white matter
What is color anomia?: Patients can perform visual-visual tasks and verbal-verbal tasks, but are unable to name colors; these patient have a right homonymous hemianopia and intact color perception of the left visual field
Where is the lesion usually located in color anomia?: Lesions are typically in the left hemisphere, mesially, in the transition between occipital and temporal lobes
What is specific color aphasia?: patients can sort colors and match them; this is often seen in the context of aphasia and there is a disproportionate difficulty in naming colors
Damage to the _____ parietal lobe may lead to specific color aphasia.: Damage to the LEFT parietal lobe may lead to specific color aphasia.
The term ______ refers to a failure to synthesize all elements of a picture or scene, even though components can be recognized in isolation.: The term SIMULTANAGNOSIA refers to a failure to synthesize all elements of a picture or scene, even though components can be recognized in isolation.
There are 3 symptoms that are characteristic of Balint's syndrome. What are they?: 1) simultanagnosia
2) ocular apraxia - inability to shift gaze vluntarily from a fixation point
3) optic ataxia - impariment of visually guided movemens
Simultanagnosia is considered a variant of ____ agnosia.: Simultanagnosia is considered a variant of APPERCEPTIVE agnosia.
What is the difference between "dorsal" simultanagnosia and "ventral" simultanagnosia?: Dorsal simultanagnosia results fro bilateral occipitoparietal lesions and the patient can't se emore than on object at a time. Ventral simultanagnosia results from left inferior occipital lesions and the patient may be able to "see" more than one object at a time.
What is ocular apraxia?: an inability to shift gaze voluntarily from a fixation point. Patients behave as though they are mesmeized by the original object. Sometimes gaze can be shifted if the eyes are closed.
What is optic ataxia?: an impairment ov visually guided movements as a result of a defect in stereopsis (depth perception). Patients with optic ataxia may not be able to read in methodical visual sweeps
____ ____ is a form of anosognosia in which the patient denies blindness because he/she believes their vision is intact.: ANTON'S SYNDROME is a form of anosognosia in which the patient denies blindness because he/she believes their vision is intact.
Cortical blindness results from what type of lesion?: Cortical blindness usually results from bilateral occipital cortex damage. Cause is usually bilateral posterior cerebral artery occlusion or occipital head trauma. Blindess may also sometimes occur due to extensive brain injury from anoxia, multiple infarctions, or MS. Vision is completely obliterated; however pupils are normal in size and reactive to light b/c the otic nerves and brainstem are intact. FYI - they may confabulate by describing things they "see" in their environment
Fun facts about Anton's syndrome...: 1) may be caused by blindsight, where the patient can see some movement but denies it
2) mediated by "second visual system" of superior colliculus, pulvinar, and parietal cortex
3) may also relate to impaired memory or insight because of associated temporal or frontal damage
In ____ objects are seen as larger than they truly are; however, in ___ objects are seen as smaller than they truly are.: In MACROPSIA objects are seen as larger than they truly are; however, in MICROPSIA objects are seen as smaller than they truly are.
What is metamorphospsia?: Metamorphospsia is a very rare disorder in which objects can be identified by they look odd. They may appear fragmented, compressed, or tilted.
Prosopagnosia typically results from bilateral ____ lesions.: Prosopagnosia typically results from bilateral OCCIPITOTEMPORAL lesions. Also sometimes occurs in the context of Alzheimer's disease.
Define auditory agnosia.: Auditory agnosis is an impairment in the ability to recognize speech or nonverbal sounds in the presence of adequate hearing.
Auditory agnosia typically occurs following damage to the ____ lobes.: Auditory agnosia typically occurs following damage to the TEMPORAL lobes. It may reflect disconnection of unimodal auditory areas specilzed for encoding the auditory properties of familiar objects from transmodal nodes that coordiante multimodal recognition. FYI - Severe damage may result in cortical deafness.
You were just told that today's patient has auditory word agnosia. What might you expect to observe when interviewing this patient?: Patients with auditory word agnosia (aka pure word deafness) have impaired recognition of speech although their hearing is intact and they are able to comprhend nonverbal sounds. They can hear voices, but cannot make sense of the words. They may complaint that the sound is muffled or sounds foreign. They are unable to repeat what has been said to them. Although this may evolve from Wernicke's aphasia, spontaneous speech, reading, and writing are all intact.
How is auditory word agnosia different from an aphasia?: In aphasias, word sounds are perceived normally but the patient cannot link the sound to meaning. In auditory word agnosia, the patient cannot recognize speech sounds. The words sound muffled or foreign.
Auditory word agnosia (aka word deafness) has been associated with lesions....: May be bilateral or unilateral left temporal. Thought to be the result of a disconnection of primary auditory area on boths sides from Wernicke's area.
True or False. TBI is the most common cause of auditory word agnosia?: False. CVA is the most common cause of auditory word agnosia.
This type of agnosia involves a deficit in recognizing environmental sounds (e.g., bell ringing, dog barking).: Auditory Sound Agnosia (the nonverbal counterpart of pure word deafness); lesion appears to be right hemisphere analog to pure word deafness
________ is the inability to recognize familiar voices and is the auditory analog of ________.: PHONAGNOSIA is the inability to recognize familiar voices and is the auditory analog of PROSOPAGNOSIA.
A patient whose daily activities and auditory behavior indicate an extreme lack of awareness of auditory stimuli is likely suffering from ____ _____.: A patient whose daily activities and auditory behavior indicate an extreme lack of awareness of auditory stimuli is likely suffering from CORTICAL DEAFNESS.
True or False? In cortical deafness, audiometric tone typcially remains normal?: False. In cortical deafness, audiometric tone is usually very ABNORMAL.
Bilateral destruction of auditory radiations or primary auditory cortex may result in ____ _____.: Bilateral destruction of auditory radiations or primary auditory cortex may result in CORTICAL DEAFNESS.
True or False. It is difficult to distinguish between auditory agnosia and cortical deafness.: True.
Define receptive amusia.: Receptive amusia (aka sensory amusia) is the loss of ability to appreciate various characteristics of heard music.
True or False? Receptive amusia is always present in patients who suffer from pure word deafness?: False. Receptive amusia occurs to some extent in all cases of auditory sound agnosia and in the majority, but not all, casers of pure word deafness.
Patients with auditory affective agnosia show impaired comprehension of ____.: Patients with auditory affective agnosia showed impaired comprehension of PROSODY.
Patients with auditory affective agnosia, usually have lesions in what brain region?: lesions are usually located in the right temporoparietal region.
True or False? Auditory affective agnosia is usually accompanied by neglect?: True.
This type of agnosia is associated with an impairment in the ability to recognize objects by palpation in hand.: Tactile agnosia
What are the two views regarding lesion localization in tactile agnosia?: 1) associated with contralateral primary somatosenory area in postcentral gyrus
2) more diffuse aspects of cortex (e.g., posterior parietal lobe) are involved in perception
Name the two types of tactile agnosia.: 1) Apperceptive
2) Associative
What is amorphognosia?: impaired recognition of size and shape of objects
When one is unable to discriminate the distinctive qualities of objects such as density, weight, texture, and thermal properties they are said to have _____.: AHYLOGNOSIA
____ ____ is impaired tactile recognition of the identity of objects in the absence of amorphognosia or ahylognosia.: TACTILE ASYMBOLY is impaired tactile recognition of the identity of objects in the absence of amorphognosia or ahylognosia.
Define apperceptive tactile agnosia.: Apperceptive tactile agnosia is equivalent to astereognosis. It is the impaired ability to discriminate objects based on physical characteristics of size, weight, shape, density, or textural cues. In other words, the patient is unable to identify objects by touch and is usually unilateral.
True or False? Apperceptive tactile agnosia is never seen with agraphesthesia.: False. Apperceptive tactile agnosia is often seen with agraphesthesia (impairment in recognition of characters on the skin of the palm)
Where is the lesion usually located in apperceptibe tactile agnosia?: lesion is usually in the contralateral primary sensory cortex.
What is associative tactile agnosia?: a disorder of tactile recognition in the absence of primary somatosensory dysfunction - it is more subtle than astereognosis
What is one of the primary differences between apperceptive and associative tactile agnosia.: Like patients with apperceptive agnosia, patients with associative agnosia cannot recognize an object in hand, BUT patients with associative agnosia CAN accurately draw the object even when palpation fails to elicit recognition.
Where is the lesion usually located in associative agnosia?: usually in the inferior parietal cortex, where high-level tactile processing occurs
There are several types theoretical models of agnosia. What are the three main TYPES of models?: 1) Stage Model
2) Disconnection Model
3) Computational Model
Provide a brief discription of Lissauer's two-stage model of perception/recognition.: After the elementary sensation (awareness of stimulus quality and intensity), the object is perceived (apperception - concsious perception of a form, object, or "thing"), then the object must be recognized (association - recognition of category or identity of the "thing"). Once these two stages (apperception and association) have been accomplished the object can be named (retrieval of the name or category)
True or False? The validity of "stage" models of perception has been called into question?: True. The validity of stage models, such as Lissauer's model, have been called into question, since perception is not normal in many associative agnosias
Geschwind suggested that agnosia results from disconnection between ____ and ___ processes.: Geschwind suggested that agnosia results from disconnection between VISUAL and VERBAL processes. For example, a patient may fail to identify an object, but later use or interact with the object normally.
True or False? One of the biggest limitations of disconnection theories is that they are unable to account for the fact that most agnostics show abnormal verbal and nonverbal processing of viewed objects.: True
Name the three types of representations according to Marr's computational model and provide a brief description of each?: 1) primal sketch: represents brightness changes across the visual fiend (results in a way of specifying the genometric shape of an object)
2. viewer-centered sketch: represents spatial locations of visible surfaces from the viewer perspective
3. object-centered sketch: specifies the configuration of surfaces w/in the object-centered coordinate frame
Briefly describe Damasio's computational model of perception.: 1) perception involves evocation of neural activity pattern in primary and first-order ass'n cortex which corresponds to various perceptual features
2. downstream, features combined in "local convergence zones"
3. does not distinguish between memory and perception which bind features of a pattern into an "entity"
4. predicts there can be no disorder of object recognition without perceptual dysfunction
True or False. Computational models of perception posit that it is possible to have a disorder of object recognition even though percpetion is intact.: False. Comutational models posit that there can be no disorder of object recognition without perceptual dysfunction.
How are computational models of perception different than other models (e.g., disconnection or stage models)?: Computational models recognize the enormous complexity involved in perceptual analysis and conclude that the brain must store representations in some kind of codable, symbolic form that is flexible enough to accommodate perceptual variations required in everyday recognition.
Briefly describe Ellis and Young's model of perception.: they posit that recognition begins by comparing viewer-centered and object-centered representation to stored structural descriptions of objects known as "object recognition units"
True or False? Gross autotopagnosia is more common than most people realize.: False. Gross autotopagnosia is rare and is not observed in isolation.
Define autotopagnosia.: Autotopagnosia is a disturbed body schema involving the inability to identify parts of one's body, either to verbal command or by imitation.
Name two limited forms of autotopagnosia.: 1) left-right disorientation
2) finger agnosia
What is finger agnosia?: Bilateral loss of the ability to name or identify the fingers
Finger agnosia is commonly observed in what syndrome? a) Balint's syndrome b) Gerstmann syndrome: Finger agnosia is a symptom of Gerstmann syndrome along with agraphia, acalculia, and right-left confusion
What are some reasons that a patient may not perform well on a finger recognition/localization task?: Failure on tests of finger recognition and finger localization may depend on the specific demans of the task employed. Patients may due poorly due to aphasic misnaming, sensory deficits, spatial disorientation, attention pxs
What is static object agnosia?: This is a visual object agnosia in which the effect is reduced when the object is moved.
In the assessment of agnosia, it is important to rule out alternative explanations for the patient's symptoms. Name some alternative explanations...: 1) anomia
2) aphasia
3) apraxia
4) visual deficits
How can you differentiate agnosia from anomia?: Anomia implies that the stored representation of the word has been lost. In anomia, the naming deficit is present regardless of the sensory modality. The patient recognizes the meaning of the object, but cannot name it. In agnosia, the object can be readily named through a different sensory modality.
How can you differentiate agnosia from aphasia?: An agnostic won't demonstrate word-finding problems in spontaneous speech and will not be able to identify misnamed objects by circumlocution.
How can you differentiate agnosia from apraxia?: Patients with apraxia cannot follow commands not requiring objects (e.g., salute, wave) or demonstrate the object when it is not seen
What are the 7 primary things you should evaluate when assessing agnosia?: 1) test color perception
2) determine which modality is affected
3) check apperception (matching, drawing, copying)
4) evaluate visual memory (designs, objects, faces, colors)
5) evaluate perception (figure/ground discrim, closure, synthetic ability, route finding)
6) evaluate associations (sorting, categorizing, pairing of similar objects, spontaneous use of an object)
7) confrontation naming (for faces, male/female? human/animal?)
** ALWAYS RULE OUT ALTERNATIVE EXPLANATIONS (e.g., anomia, aphasia, apraxia)

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