Mark A. Wheeler

Frontal lobe damage produces episodic memory impairment.

This article reports the outcome of a meta-analysis of the relation between the frontal lobes and memory as measured by tests of recognition, cued recall, and free recall. We reviewed experiments in which patients with documented, circumscribed frontal pathology were compared with normal control subjects on these three types of tests. Contrary to conventional wisdom, there is strong evidence that frontal damage disrupts performance on all three types of tests, with the greatest impairment in free recall, and the smallest in recognition.

Different rates of forgetting following study versus test trials

Two experiments investigated recall following two study conditions, (1) repeated test: a study trial followed by multiple recall trials, and (2) repeated study: multiple study trials with no tests. At a retention interval of 5 minutes, repeated study produced a higher level of recall than repeated test. When the retention interval was extended, forgetting was much more rapid in the study condition, with the repeated test manipulation leading to higher recall at an interval of 7 days. We conclude that study and test trials have different effects upon memory, with study trials promoting memory acquisition, and test trials enhancing the retrieval process itself, which protects against subsequent forgetting.

Remembering and Knowing in Patients with Frontal Lobe Injuries

Two experiments compared the performance of patients with pathology restricted to the prefrontal cortex to healthy controls on recognition tests that were followed by the remember/know procedure. Across both experiments, patients recognized roughly as many target items as control participants. Injuries centered in the frontal poles resulted in deficits that were selective to episodic remembering while apparently sparing semantic knowing. Patients with lesions restricted to dorsolateral prefrontal cortex were not impaired at either remembering or knowing. Results demonstrate a dissociation of cognitive function within the prefrontal cortex, and suggest that episodic remembering may share a family resemblance with other neurocognitive functions dependent upon polar aspects of the frontal lobes, such as self-recognition, anticipation, and planning.

Self‐face processing in a callosotomy patient

Self‐face recognition is reserved for humans, apes and possibly dolphins and is thought to be a marker of self‐awareness. Previous data have indicated that self‐face recognition may be mediated via frontal right hemisphere circuits within the brain. Testing patient M.L., who underwent a total callosotomy, we found that when searching for the self‐face in a series of morphs (composite facial images made up of his own and a famous face in inversely varying percentages) the patient made (i) more true‐positive and (ii) fewer false‐positive responses when responding with the right hemisphere (i.e. indicating with the left hand). There was no hand difference when searching for familiar faces. These data imply a right hemisphere processing advantage for self‐faces.

Focal retrograde amnesia and the episodic- semantic distinction

This article reports a review of focal retrograde amnesia (FRA), or the phenomenon of organically based severe memory loss restricted to retrograde, or pretraumatic, memory. Cases of FRA are classified according to the type of memory loss: episodic, semantic, or both. A few different clusters of the disorder were identified. Lesions to either the anterior temporal lobes or the posterior/visual cortex can result in an FRA that devastates retrograde episodic memory, while having smaller effects on semantic memory. A number of left-hemisphere patients have FRA confined to semantic memory. There are several additional examples of FRA following minor cerebral trauma that disrupts either episodic memory alone or both episodic and semantic memory that are not accompanied by evidence of structural brain lesions. We discuss these different profiles of FRA and their implications for the understanding of memory retrieval.