Which of the following is true about limb-kinetic apraxia?
D. Limb-kinetic apraxia most often occurs in the limb contralateral to a hemispheric lesion, usually to the premotor cortex. Patients with limb-kinetic apraxia demonstrate a loss of deftness and ability to make finely graded, precise, independent finger movements. These subjects will not be able to use a pincher grasp to pick up a penny. They will have trouble rotating a coin between the thumb, middle finger, and little finger.
Reference:
Which of the following refers to defective recognition of sensory stimuli despite having intact sensory pathways?
A. The term agnosia was originally introduced by Freud. In general, patients with agnosia have clinical feature of impaired recognition of sensory stimuli despite normal sensory pathways. Agnosia represents a disorder of higher-order sensory processing. There is an impaired ability to recognize the nature or meaning of sensory stimuli. This is usually modality specific. There are two basic categories of agnosia. Apperceptive agnosia involves impaired generation of the minimal integrated percept necessary for meaningful recognition. This defect, leads to the formation of an inadequate minimal object recognition unit (i.e. the minimum information required to meaningfully interpret the percept). For example, a "pencil" is initially perceived as—"long, thin, pointed at one end, etc", before a meaning ("it is a pencil—it is used to write") is attributed to the percept. Patients are unable to distinguish visual shapes and so have trouble recognizing, copying, or discriminating between different visual stimuli. Associative agnosia involves defective association of meaning with percepts. The defect is in associating a correctly perceived percept with its meaning. Patients can describe visual scenes and classes of objects but still fail to recognize them. Patients suffering from associative agnosia are still able to reproduce an image through copying. Anosognosia refers to being unaware of a neurological state/illness. Abulia refers to loss of drive or motivation seen in cingulate lesions.
A 55-year-old man finds it difficult to recognize faces. On further testing, his ability to discriminate faces and match faces is intact.
The most likely condition he is suffering from is:
B. Since this person has a difficulty in recognizing faces, he is suffering from prosopagnosia. In this situation, he can differentiate between faces. So, the defect is probably at a step after the formation of the minimal recognition unit (described in the previous question), but at the step where the percept (in this case the face) is associated with a meaning (‘whose face it is’). So this patient is most probably suffering from associative prosopagnosia.
Which of the following is true regarding episodic memory?
C. Memories of specific experiences formed in specific contexts are called episodic, for example the meal one had 3 weeks ago at a restaurant. Episodic memory is explicit, that is it is consciously acquired (we know how and where we acquire it) and declarative, that is it can be consciously recalled. Episodic memory depends largely on the integrity of the medial temporal lobe, but there are other structures that are involved in episodic memory. These include the frontal lobe, basal forebrain, retrosplenial cortex, presubiculum, fornix, mammillary bodies, mammillothalamic tract, anterior nucleus of the thalamus, etc. Damage to any one of these structures can result in deficits in episodic memory. Hence episodic memory loss cannot be said to be characteristic of a medial temporal lesion. Episodic memory impairment could manifest as anterograde or retrograde amnesia. Anterograde amnesia refers to impairment in new memory formation and retrograde amnesia refers to the loss of previously acquired memories. Episodic memory applies to both personal and public events. In most dementias, semantic memory loss occurs at later stages than episodic memory loss.
During bedside cognitive testing, a 40-year-old patient is asked to give the years when World War II took place.
Which of the following memories is tested here?
C. Semantic memory describes memories for general information which is unrelated to other information, for example dates in history, the colour of our national flag, or the characteristics of different species of dinosaurs (encyclopaedic facts). Semantic memory is explicit and declarative (see explanation to the previous question). In the most general sense, semantic memory refers to all of our knowledge of the world; however, semantic memory is more usually tested in the context of naming and categorization tasks. It is localized to the inferior lateral temporal lobes. The frontal lobes are responsible for providing information to, and retrieving information out of, the semantic memory banks.
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