- To investigate
the damage to the medial temporal lobe (MTL)
- Anterolateral Temporal cortex on semantic knowledge
- Assess the relation between test performance and the extent of damage to lateral temporal cortex.
- To determine whether HM’s performance was unique among the patients
- Use of case studies of brain-damaged patients compared to ‘normal pp
- To investigate the damage to the medial temporal lobe (MTL)
- three patients
who developed amnesia after herpes simplex encephalitis
- These patients have large medial temporal lobe lesions, as well as variable damage to anterolateral temporal cortex (MTL).
- We also studied patient H.M., who underwent bilateral medial temporal lobe resection for relief of severe epilepsy
- Other participants included two amnesic patients with damage believed to be limited to the hippocampal formation
- There was 8 controls within this study.
- These controls were volunteers. They were matched to the older patients with respect to age (74.0 years) and education (12.4 years)
- three patients who developed amnesia after herpes simplex encephalitis
- 9 tests were
conducted over 3 to 5 different sessions with
- . 7 of these tests were from the Semantic Test Battery and 2 tests were constructed by the researchers.
- The tests were all based on line drawings of 24 animals and 24 objects.
- 9 tests were conducted over 3 to 5 different sessions with participants
- MRI scans of MTL patients, 1/2 HF patients
- Seven of the 9 tests are from the Semantic Test Battery
- All nine tests were based on the same line drawings of 24 animals and 24 objects (or their names)
- Each of the 48
items could further be assigned to one of 8 categories
- 6 domestic land animals, 6 foreign land animals, 6 water creatures, 6 birds, 6 electrical household items, 6 nonelectrical household items, 6 vehicles, and 6 musical instruments
- There was no time limit
- On 13 tests of semantic memory, patients with lesions limited to the hippocampal formation performed similarly to controls
- Postencephalitic patients were mildly to moderately impaired on most tests
- Patient H.M.’s performance was impaired on only a few tests and was less severely impaired overall than the three postencephalitic patients.
- A ranking of test scores showed a direct relationship between impairment and the extent of damage to lateral temporal cortex