The Department of Biomedicine

BBB seminar: Terje Lømo

How impulse activity shapes structure and function in brain and muscle

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Terje Lømo
Professor emerit., Department of Physiology, University of Oslo

The function of nerve cells is to generate electrical impulses and pass these impulses on to other nerve cells in large networks of interconnected cells. Such impulses form patterns of activity that not only contain essential information but also ensure that our brain and muscles develop and function normally. Impulse activity in nerve cells arises in constant interaction with the environment. Hence, the old debate "nature or nurture" is no longer relevant. Both nature, in terms of genes, and nurture, in terms of environmentally dependent impulse activities, determine the fate of our brains and hence our fate as human beings.

To begin with, the maturing brain produces an excessive number of nerve cells, many of which die soon afterwards. Similarly, nerve cells initially form an excessive number of synaptic connections, many of which then become eliminated. Such cell death and synapse elimination are essential for normal brain and muscle development and both depend on impulse activity. Perhaps all learning in youngsters and adults alike depends on the flow of nerve impulses and the manner in which these impulses result in persistent changes in the synaptic connections between nerve cells. As the efficiency of synaptic transmission either increases or decreases, functional networks of nerve cells form that can store our memories and improve our performances.

While the brain learns, muscles adapt to whatever the brain instructs them to do. Thus muscles may become rapidly or slowly contracting, sensitive or resistant to fatigue, strong or weak depending on the tasks imposed by the brain. Again, such adaptation depends on the particular patterns of impulse activities that the brain sends to the muscles. To identify the molecular and cellular mechanisms that explain how nerve and muscle cells adjust their properties to received impulse patterns is a major research goal in neuroscience today.

In this lecture examples will be presented to illuminate how impulse activity contributes to making us what we are. These examples will deal with evidence that impulse activity in the brain can cause persistent synaptic changes that may underlie learning and memory, ensure normal development of muscle fibres and synapses between nerves and muscle fibres, and finally, control movement and muscle adaptation.

Key references:
Bliss TV and Lømo T. 1973. Long-lasting potentiation of synaptic transmission in the dentate area of the anaesthetized rabbit following stimulation of the perforant path. J Physiol 232: 331-356.
Lømo T. 2003. The discovery of long-term potentiation. Philos Trans R Soc Lond B Biol Sci 358: 617-620.

Dr. Terje Lømo discovered the principle of long-term potentiation (LTP) in 1966 during his research for the degree of Dr. medicinae in Per Andersen's laboratory in Oslo. In 1968 Lømo performed the experiments that resulted in a paper (Bliss and Lømo, J Physiol. 1973, 232:331) that is now considered to be the basic reference for LTP. The discovery is regarded as one of the most fundamental principles for our understanding of memory. In recognition of this endeavour Terje Lømo received the Anders Jahre Award for Medical Research of 2003. He was the first Norwegian since 1988 to receive this prestigious honour. Terje Lømo`s present research interest is focused on two aspects of neuromuscular signalling, (a) on the targeting of functional subtypes of spinal motoneurons and skeletal muscle fibres in vivo by intramuscular injection of adenoviral and adeno-associated viral vectors, and (b) on how electrical muscle activity pattern modulate transcriptional and posttranscriptional mechanisms in skeletal muscle.