Date(s) - 18 Sep 2015
1:00 PM - 2:00 PM
3043 ECpE Building Addition
Title: Non-invasive brain stimulation: challenges and subtleties of stimulating the human brain in conscious individuals
Speaker: John Rothwell, Professor, University College London
Abstract: Over the past 30 years, a number of new approaches have been developed to stimulate the human brain painlessly in conscious behaving participants. The methods fall into two categories: those that evoke spiking activity in neurons and those that bias their basal levels of excitability. Transcranial magnetic stimulation (TMS) is the prime example of the former and works by using a large but transient magnetic field to induce a short duration pulse of electric current in the brain. Transcranial direct current stimulation (TDCS) is an example of the latter and employs a small DC current applied through electrodes on the scalp to polarize the membrane potential of neurons, bringing them closer to, or further from their discharge threshold. Both methods have been shown to interact with excitability of cortical neurons and to influence behaviours such as reaction times and task accuracy. They may also produce short term after-effects that engage early stages of synaptic plasticity in underlying cortex. Since these processes are fundamental to learning and memory they can change learning rates and memory.
Clearly such methods have great potential, yet their use is still not widespread. One of the main reasons for this is interindividual variation in the response to stimulation: some people may respond as expected whereas other may respond oppositely. It is thought that much of the reason for this lies in the non-specific nature of the methods. They activate large brain areas with a mixture of cell types, which themselves can have opposing functions. We see only a net effect of many different processes. I will discuss how new methods may allow better targeting of stimulation and improve the reliability of the methods.
Speaker Bio: John Rothwell is a professor of neurophysiology at the Institute of Neurology, Queen Square, London. His main area of interest is transcranial magnetic stimulation and motor control. His group has pioneered the use of the paired-pulse technique (Kujirai et al. 1992), interhemispheric studies (Ferbert et al. 1992). Rothwell was educated at the University of Cambridge and progressed to a MRC Fellowship. He did his PhD under David Marsden. He became head of the MRC Human Movement and Balance Unit upon the untimely death of David Marsden. He has written over 400 papers and numerous chapters.