The present experiment investigated differences in processing between young and old adults in a combined visual selection‐memory search paradigm. No evidence was found for age‐related differences in early visual selective attention. The elderly achieved relatively fast reaction times in the memory search task at the cost of a high error percentage. From these findings, and from the morphology of the event‐related potential, it was concluded that old subjects perform controlled memory search more superficially than young subjects, In both old and young subjects high memory load was associated with decreased positivity in the P3 and Slow Wave area. This is interpreted in terms of Okita et al.'s(1985) concept of search negativity. N2 amplitude was found to be larger to non‐target trials for both attended and unattended inputs. The latter result is discussed in relation to theories about N2 as an indicator of automatic mismatch detection.

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Neurophysiological studies of diabetic patients may show abnormalities even when clinical examination has revealed no sign of neuropathy. Quantitation of sensory function provides additional information when examining a patient with neuropathy. The value of the Hoffmann (H) reflex was investigated in diabetics who had undergone this examination. H-M intervals of the H-reflex, vibration perception thresholds (VPT's) and thermal discrimination thresholds (TDT's) were determined in 34 diabetics with clinical evidence of neuropathy and 16 diabetics without symptoms or signs of neuropathy. Normal values for VPT and TDT were obtained from the examination of 40 healthy subjects. The values of the H-M interval were significantly correlated with VPT's and not with TDT's. Three patients with clinical evidence of neuropathy and abnormal VPT's and TDT's had normal H-M intervals. For research purposes it is recommended that H-reflex studies are combined with the determination of sensory thresholds, but from a practical point of view determination of the H-M interval proved to be an effective tool for the investigation of neuropathy in diabetic patients.

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It has been proposed that increased polyol pathway activity resulting from hyperglycaemia induces neuropathy in diabetic patients. Recently, it has been demonstrated that erythrocyte sorbitol content is a reflection of polyol pathway activity in nerve. In the present study the relationship of erythrocyte sorbitol and glycosylated haemoglobin (HbA1) levels to peripheral nerve functions were investigated in 62 diabetic patients. Peroneal and median motor nerve conduction velocities, H-M intervals of the Hoffmann reflex, thermal discrimination thresholds and vibratory perception thresholds, either singly or in combination, were not significantly correlated with erythrocyte sorbitol or HbA1 levels. These findings show that a single measurement of erythrocyte sorbitol or HbA1 content cannot predict impairment of nerve function in diabetic subjects.