Frontal lobes
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Temporal lobes
Semantic dementia
Alzheimer's disease
Fronto-Temporal Dementia
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Symptoms: progressive semantic deficits - pruning of the semantic tree (in early SD)
Deficits typically progress to other cognitive domains inc behaviour (symptoms of frontotemporal dementia)
Cause: see cause of fronto-temporal dementia
Cause: Frontotemporal dementia is caused by clumps of abnormal protein forming inside brain cells. These are thought to damage the cells and stop them working properly.
The proteins mainly build up in the frontal and temporal lobes of the brain at the front and sides. It's not fully understood why this happens, but there's often a genetic link.
Cause: a number of causes including protein accumulation (amyloid, neurofibrillary tangles), chronic inflammations and brain atrophy
Specific brain regions: anterior temporal lobe (hypothesised as amodal semantic hub)
Specific brain regions: early deficits associated with the medial temporal lobe
Symptoms: early symptoms include episodic memory deficits
Symptoms: personality and behavioural changes, language problems, attention, memory problems
Korsakoff's syndrome
Specific brain regions: this area is still controversial but one supported view is that the critical lesion site for the disorder is the anterior thalamic nuclei where these nuclei are seen as part of the limbic-diencephalic memory circuit, like the hippocampus.
Cause: commonly caused by chronic alcohol abuse resulting in a lack of vitamin B1 (thiamine) which helps the brain cells to produce energy to function properly.
Symptoms: Episodic memory dysfunction specifically regarding context (temporal). Executive function impairment also observed in the area of context reconstruction.
Key findings: Impaired on both explicit and implicit memory tasks (Berry et al., 2014).
Herpes simplex virus encephalitis
Specific brain regions: affects the medial and lateral temporal lobes
Cause: Viral infection
Symptoms: Associated with poor semantic memory but also impaired episodic memory and other functions