These developments led to Sir William Preece, chief engineer for the General Post Office, performing his own experiments on wireless by conduction and also on wireless by induction, after which he instead turned to backing the efforts of a clever Italian named Guglielmo Marconi. About the same time, James Lindsay was experimenting with sending telegraph signals through ponds in and around Dundee, after which he succeeded in signalling across the River Tay over a distance of more than two miles. This allowed signals to be sent through water over nearly a mile. Notably, in 1842, Samuel Morse laid wires along each bank of the Susquehanna River, connecting the transmitting key and a battery to wires to a pair of copper plates upstream and downstream, with a galvanometer on the opposite bank connected to wires to a second set of plates opposite the first set. Nonetheless attempts to send messages through water pre-date attempts to send them through the air. Intended applications are mainly in the offshore oil and gas industries, but it also has great potential for use in oceanographic research and by the military.Ĭonventional radio does not work under water because of the conducting nature of the medium especially in the case of sea water. While it is not suitable for voice transmission over long distances, it does allow voice transmission over short distances, and more importantly, the transmission of data at high rates for control and telemetry. "The implications are that such directed fields can be used to modulate both pathological activities, such as seizures, and to interact with cognitive rhythms that help regulate a variety of processes in the brain.Tom Shelley reports on a way of transmitting information by radio beneath the wavesĪ system under development permits the transmission of electronic data underwater using electromagnetic radio waves. Schiff, director of the Centre for Neural Engineering at Penn State University, who wasn't involved in the research. "Others have been working on such phenomena for decades, but no one has ever made these connections," said Steven J. If their findings, which are reported in The Journal of Neuroscience, can be expounded in further studies, it could help us to better understand how brain waves are associated with things like memory, epilepsy, and healthy physiology. "This novel mechanism coupling cell-by-volume conduction could be involved in other types of propagating neural signals, such as slow-wave sleep, sharp hippocampal waves, theta waves, or seizures." "The results indicate that electric fields (ephaptic effects) are capable of mediating propagation of self-regenerating neural waves," they write. Testing on mouse hippocampi (the central part of the brain associated with memory and spatial navigation) produced similar results, and when the researchers applied a blocking field, it slowed down the speed of the wave.Īccording to the researchers, this is evidence that the propagation mechanism for the activity is consistent with the electrical field. While the field is of low amplitude (approximately 2–6 mV/mm), it's able to excite and activate immediate neighbours, which subsequently activate more neurons, travelling across the brain at about 10 centimetres per second.
Running computer simulations to model their hypothesis, the researchers found that electrical fields can mediate propagation across layers of neurons. "But it appears the brain may be using the fields to communicate without synaptic transmissions, gap junctions or diffusion." "Researchers have thought that the brain's endogenous electrical fields are too weak to propagate wave transmission," said Dominique Durand, a biomedical engineer at Case Western Reserve University. In the absence of other plausible explanations, the scientists believe these brain waves are being transmitted by a weak electrical field, and they've been able to detect one of these in mice. Researchers in the US have recorded neural spikes travelling too slowly in the brain to be explained by conventional signalling mechanisms.
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