15.5. The Temporal Lobe
The temporal lobe's distributed functions include receptive speech, particularly Wernicke's area and the basal temporal language area. The inferior temporal gyrus is essential for object recognition while the middle temporal gyrus visual area is vital for recognition and tracking of moving objects. The dorsal parietal areas are most important for delineating interest and position of objects. Medial temporal lobe structures are pivotal for registration and consolidation of short term memory. The temporal lobes are one of the anatomical substrates of personality in and of itself due to its anatomical projections to the limbic system and frontal lobe (uncinate fasciculus).
Left Temporal Lobe
- Wernicke's aphasia (BA 22, BA 23)
- Rostral pole (proper name anomia)
- Sensory conduction aphasia
- Short term memory loss
- Basal temporal language area:
- Receptive speech/anomia
- Deficits in confrontational naming
- Color anomia:
- Medial temporal lobe
- Fusiform gyrus
- Temporal/occipital junction
- Semantic memory:
- Left inferior temporal gyrus
- Superior temporal gyrus:
- Grammatical comprehension:
- Temporo-parietal junction:
Right Temporal Lobe
- Anterior temporal lobe:
- Amusia
- Aprosody
- Agitated delirium:
- Superior and middle temporal gyrus
- Aura of hunger
- Priming for memory
- Non-verbal amnesia
- Pathologic crying
- Right hippocampus
- Non-verbal task processing:
- Spatial information
- Less readily verbalizable visual stimuli
- Parahippocampal gyrus:
- Encoding of spatial information for long term storage
Bitemporal Lobe Diseases
- Klüve–Bucy Syndrome (KBS)
- Hypermetamorphopsia (all objects receive the same visual attention)
- Hyperorality
- Hypersexuality
- Sham rage
- Severe memory deficits
Differential Diagnosis of Causes of Klüve–Bucy Syndrome
- Herpes simplex
- Head trauma
- Radiation through the temporal lobes (pituitary tumors)
- Kindling from an opposite temporal focus
- Temporal lobectomy:
- The opposite side is defective
Amygdala
- Seizure (order of signs)
- Freezing response
- Pale (lack of emotional expression)
- Slow contralateral turning (may be ipsilateral turning as well)
- Automatism:
- Smacking the lips or chewing
- Medial nuclear group discharge:
- Ictal fear:
- Abdominal location
- Free-floating; cannot be linked with an expected or past event
- Associated with excessive anxiety
- Feeling of impending doom
- Urbach--Wiethe disease (calcification of the amydala)
- Defective:
- Processing of emotional facial expression
- Emotional prosody
- Emotional memory
- Bilateral amydala damage:
- Impaired in processing fear in facial expressions
- Defective prosody
- Normal intelligence
- Calcification of the amydala bilaterally in 50% of patients
Cingulate Gyrus
The cingulate gyrus is an integral component of the anterior limbic system which is composed of the mamillary bodies, the mamillothalamic tract, anteroventral thalamic nucleus and the hippocampus. It is involved in those conditions that affect the limbic system specifically such as herpes simplex infection, anti-Hu antibody mediated paraneoplastic encephalomyelitis and seizure disorders. It distributed functions are associated with attention, motivation, the effectual components of movements, and the "suffering" component of pain.
General Features of the Cingulate Gyrus
- Anterior cingulated gyrus (BA 24):
- Deficits in motivation
- Activated by movement (dorsal)
- Lesions may be associated with bradykinesia
- Specific anterior cingulated gyrus functions:
- Selection of targets from competing inputs
- Divided attention
- Selection of action
- Modulates autonomic activity
- Generates internal emotional responses
- Integrates emotional and cognitive aspects of behavior
Posterior Cingulated Gyrus
- Learning and memory impairment
- Activated with pain (right side)
General Cingulate Signs
- Tic disorders have been described with interruption of pathways to the orbitofrontal cortex
- Obsessive compulsive behavior
- Hemineglect of contralateral space
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