Human EEG and the mechanisms of memory: investigating long-term potentiation (LTP) in sensory-evoked potentials

ABSTRACT

Long-term potentiation (LTP) at synapses within neural networks is the most likely candidate mechanism for learning and memory. LTP has been extensively studied in laboratory animals, but inquiry into the functional significance of LTP had, until the mid-2000s, been compromised by the lack of a human model. In this brief review, we describe the results of paradigms developed in our laboratory for inducing ‘LTP-like’ changes in human EEG-derived visual-, and auditory-evoked potentials. We describe how rapid, repetitive presentation of sensory stimuli leads to a long-lasting amplitude increase in some components of sensory-evoked potentials in neurotypical humans. Subsequent experiments, by us and others, investigating the locus, stimulus specificity, NMDA receptor dependence, and genetics of these ‘LTP-like’ effects suggest that they have the essential characteristics of LTP seen in experimental animals. We suggest therefore, that the increased amplitudes of components of sensory-evoked potentials are due to LTP at synapses in the neural networks generating the scalp-level EEG-derived evoked potentials. Thus, the ability to elicit and measure LTP from people other than those undergoing surgery provides a human model system allowing the detailed examination of synaptic plasticity in neurotypical subjects, and has been shown to have clinical applications in a number of disorders.

KEYWORDS:

• LTP
• learning
• memory
• adult
• aging
• evoked potential
• EEG

Acknowledgements

Studies from our laboratories at the University of Auckland have been supported by grants from the NIH (USA), the NZ Royal Society Marsden Fund (IJK), and the NZ Neurological Foundation.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Neurological Foundation of New Zealand; The Faculty of Science Development Fund, The University of Auckland; The National Institute of Health (USA); The Royal Society of New Zealand Marsden Fund.