Thursday 8th Nov, 2012, 14:00-16:50
Whole-cell patch-clampingSingle neurons
MicrostimulationSingle units / multi-units
MacrostimulationNuclei / large areas (e.g., deep brain stimulation (DBS)
CoolingArea near cooling probes
PharmacologyArea/neurons/receptors exposed to or affected by drugs
Transcranial electrical stimulation (TES)Brain areas between electrodes
Transcranial magnetic stimulation (TMS)Brain areas ~1cm diameter
Transcranial direct current stimulation (TDCS)Brain areas between electrodes
Transcranial random noise stimulation (TRNS)Not sure yet...
(Transcutaneous) Peripheral nerve stimulation (PNS)Single nerves
Static magnetic stimulation~5cm of brain
Cohen D (1984). Feasibility of a magnetic stimulator for the brain. In Biomagnetism: applications and theory. Editors: Weinberg H, Stroink G & Katila T. Pergamon press, p. 466-470.
Barker AT, Jalinous R & Freeston I (1985). Non-invasive magnetic stimulation of the human motor cortex. Lancet 1:1106-1107.
Ueno S, Tashiro T & Harada K (1988). Localized stimulation of neural tissue in the brain by means of a paired configuration of time-varying magnetic fields. J Appl. Physics 64:5862-5864.
1987/88 Cadwell Laboratories Inc., repetitive stimulation with water-cooled coil
Orientationaligned with axons
Frequencylow <=1Hz vs high >1Hz
Patternlength & separation of pulse trains
Strong, rapidly-alternating magnetic fields have the potential to induce seizures, both in healthy and in seizure-prone people.
All possible precautions must be taken to screen-out anyone to whom TMS presents an increased risk:
Required reading for all TMS users. Describes different methods & clinical uses of TMS. Collates all known data on adverse reactions to TMS. Attempts to standardise terminology. Sets safety guidelines.
Redrawn from Rossi et al. (2009)
TMS (& PNS) has been used most for studying cortico-motor transduction - the transmission of motor signals from primary motor cortex to muscles
And sensory-motor interactions
The key techniques are:
MEP amplitude & latency tell you about the level of excitability in the cortico-motor pathway and the speed of conduction
FDI muscle, right hand
Size (& variability) of MEPs varies with:
The size & latency of M-waves and H-reflexes can tell you about peripheral nerve-spine conduction
ppTMS comes in two forms: Two pulses from the same coil or two pulses from different coils
Two different coils:
And people are doing triple- and quadri- and other coil combinations now
One coil, two pulses, close together (e.g., 1-50ms)
There's also LICI, LICF, and interactions among all these acronymns - see R Chen's work
Two main kinds:
For creating a 'virtual lesion' of an area. Effects last about half as long as the stimulation
For interfering with a task during its performance: e.g., 2-5 pulses at 10-20Hz during your task
TMS pulses are delivered in repeated trains of a certain frequency.
Each train has a certain duration.
Trains are separated by a certain duration
Theta-burst stimulation is the most popular...
Designed to mimic the tetatic stimulation that is most effective at inducing long term potentiation (LTP) and depression (LTD) in neurons of hippocampal slices
A recent article suggests that these effects depend on the subjects...
Chen, R. (2004). Interactions between inhibitory and excitatory circuits in the human motor cortex. Experimental Brain Research, 154(1), 1–10. [NB]
Classen, J., Steinfelder, B., Liepert, J., Stefan, K., Celnik, P. A., Cohen, L. G., Hess, A., Kunesch, E., & Chen, R. (2000). Cutaneomotor integration in humans is somatotopically organized at various levels of the nervous system and is task dependent. Experimental Brain Research, 130(1), 48–59. [NB]
Funke, K., & Benali, A. (2011). Modulation of cortical inhibition by rtms – findings obtained from animal models. Journal of Physiology, 589(18), 4423–4435. [NB]
Koch, G., Del Olmo, M. F., Cheeran, B. J., Ruge, D., Schippling, S., Caltagirone, C., & Rothwell, J. C. (2007). Focal stimulation of the posterior parietal cortex increases the excitability of the ipsilateral motor cortex. Journal of Neuroscience, 27(25), 6815–6822. [NB]
Mars, R. B., Klein, M. C., Neubert, F., Olivier, E., Buch, E. R., Boorman, E. D., & Rushworth, M. F. S. (2009). Short-latency influence of medial frontal cortex on primary motor cortex during action selection under conflict. Journal of Neuroscience, 29(21), 6926–6931. [NB]
Neubert, F., Mars, R. B., Buch, E. R., Olivier, E., & Rushworth, M. F. S. (2010). Cortical and subcortical interactions during action reprogramming and their related white matter pathways. Proceedings of the National Academy of Sciences USA, 107(30), 13240–13245. [NB]
Oliviero, A., Mordillo-Mateos, L., Arias, P., Panyavin, I., Foffani, G., & Aguilar, J. (2011). Transcranial static magnetic field stimulation of the human motor cortex. Journal of Physiology, 589(20), 4949–4958. [NB]
Rossi, S., Hallett, M., Rossini, P. M., Pascual-Leone, A., & The Safety of TMS Consensus Group, . (2009). Safety, ethical considerations, and application guidelines for the use of transcranial magnetic stimulation in clinical practice and research. Clinical Neurophysiology, 120(12), 2008–2039. [NB]
Rothwell, J. C., Day, B. L., Thompson, P. D., & Kujirai, T. (2009). Short latency intracortical inhibition: One of the most popular tools in human motor neurophysiology. Journal of Physiology, 587(1), 11–122. [NB]
Ueno, S., Tashiro, T., & Harada, K. (1988). Localised stimulation of neural tissue in the brain by means of a paired configuration of time-varying magnetic fields. Journal of Applied Physics, 64, 5862–5864. [NB]
Vucic, S., Cheah, B. C., & Kiernan, M. C. (2009b). Defining the mechanisms that underlie cortical hyperexcitability in amyotrophic lateral sclerosis. Experimental Neurology, 220(1), 177–182. [NB]
Walsh, V. Z., & Cowey, A. (2000). Transcranial magnetic stimulation and cognitive neuroscience. Nature Reviews Neuroscience, 1(1), 73–79. [NB]