Paradigms for recording cognitive brain electrical activity.

Human event-related potentials reflect cognitive processing, and are normally elicited by external events, such as acoustic sounds or visual stimuli. As such they provide an opportunity to study normal and abnormal brain function noninvasively, at sub-second resolution. Advances in multimedia technology permit specialists in informatics and neuropsychology to co-operate in the design and implementation of paradigms, which influence ERP components. The paper illustrates the progression from standard paradigms such as the auditory oddball, which can be used to study memory update through to contingent negative variation and three condition, visual paradigms which can be used to study cognitive and emotional responses. Data from a study investigating the comparative processing of target pictures and words illustrate how external stimuli influence the later cognitive potentials.

Deficits in water escape performance and alterations in hippocampal cholinergic mechanisms associated with neonatal monosodium glutamate treatment in mice.

Mice treated neonatally with monosodium glutamate (MSG) were found to have learning and memory deficits in performing a non-spatial water escape task. Scopolamine impaired the water-escape performance of the control mice but not that of the MSG-treated mice. It was suggested that the water-escape performance deficit in the MSG-treated mice was a result of impaired central cholinergic mechanisms. As such, scopolamine was unable to further incapacitate an already impaired cholinergic system. This is strongly supported by the decreased affinity of the sodium-dependent high-affinity choline uptake observed in the hippocampus. D-Cycloserine, a partial agonist at the glycine site of the NMDA receptor, did not affect the water-escape performance of the MSG-treated and control mice; nor did it alter the effects of scopolamine. This lack of effect of D-Cycloserine may imply that the NMDA receptors are not involved in non-spatial learning, in contrast to their reported involvement in spatial learning.