Frontal-lobe Contribution to Recency Judgements

Three recency-discrimination tasks (involving concrete words, representational drawings and abstract paintings) were administered to 117 patients who had undergone unilateral cortical removals, and to 20 normal control subjects. Frontal or anterior temporal-lobe excision did not impair simple item recognition, and neither left nor right anterior-temporal lobectomy affected recency judgements on any task. In contrast, excisions that encroached on the mid-lateral frontal cortex impaired verbal recency judgements, the deficit being mild after right frontal lobectomy. Patients with right frontal-lobe removals showed the greatest impairment in recency discrimination on the two pictorial tests. The results provide evidence for hemispheric specialization related to the nature of the stimulus material and some support for a functional role for the left mid-lateral frontal cortex in verbal recency judgements.