Timeline
The discoveries that today's breakthroughs stand on. New milestones are added when a result proves durable.
Before 1900
- 1791
Galvani's "animal electricity"
Luigi Galvani publishes his experiments showing that frog leg muscles contract when touched with metals, arguing that living tissue carries its own electricity. The resulting debate with Alessandro Volta also led to the electric battery.
Luigi Galvani - 1843
The nerve impulse is electrical
Emil du Bois-Reymond records the "negative variation", the electrical signal that travels along nerve and muscle and is now called the action potential. He also measures currents leaking from injured tissue.
Emil du Bois-Reymond - 1873
Electrical signals in a plant
John Burdon-Sanderson records electrical activity in the Venus flytrap when its trigger hairs are touched. This is the first clear evidence that plants use electrical signalling.
John Burdon-Sanderson
1900s
- 1902
The membrane hypothesis
Julius Bernstein proposes that a cell's resting voltage comes from a membrane that is selectively permeable to potassium, and that excitation is a temporary breakdown of that selectivity.
Julius Bernstein - 1924
First human EEG
Hans Berger records the electrical activity of the human brain through the scalp. He publishes the work in 1929, founding electroencephalography.
Hans Berger
1950s
- 1952
Hodgkin–Huxley model of the action potential
Working on the squid giant axon, Alan Hodgkin and Andrew Huxley describe quantitatively how sodium and potassium currents produce the nerve impulse. The model is still the basis of computational neuroscience.
Alan Hodgkin, Andrew Huxley - 1958
First fully implanted pacemaker
In Stockholm, Rune Elmqvist and Åke Senning implant the first fully internal cardiac pacemaker, a starting point for implantable bioelectronic medicine.
Rune Elmqvist, Åke Senning - 1974
Measuring currents around living cells
Lionel Jaffe and Richard Nuccitelli introduce the ultrasensitive vibrating probe. It reveals steady ionic currents around developing eggs, embryos and regenerating tissues, which became the experimental basis of developmental bioelectricity.
Lionel Jaffe, Richard Nuccitelli
1975s
- 1976
The patch clamp
Erwin Neher and Bert Sakmann record currents through single ion channels for the first time. The technique won the 1991 Nobel Prize and became the standard tool of electrophysiology.
Erwin Neher, Bert Sakmann - 1997
Vagus nerve stimulation approved for epilepsy
The US FDA approves vagus nerve stimulation for drug-resistant epilepsy, the first approved therapy built on stimulating a peripheral nerve to treat a brain disorder.
2000s
- 2000
The inflammatory reflex
Kevin Tracey's group shows that stimulating the vagus nerve suppresses release of the inflammatory cytokine TNF. This links the nervous system to immune control and opens the way to electrical treatments for inflammatory disease.
Kevin TraceyNature ↗ - 2005
Optogenetics in neurons
Neurons expressing the algal light-gated channel channelrhodopsin-2 are shown to fire on command with millisecond flashes of light, giving researchers precise control over cell voltage.
Edward Boyden, Feng Zhang, Ernst Bamberg, Georg Nagel, Karl Deisseroth - 2005
Microbial nanowires
Derek Lovley's group reports that *Geobacter* bacteria use conductive protein filaments to pass electrons to iron minerals outside the cell, starting the study of microbial nanowires.
Derek LovleyNature ↗ - 2006
Wound fields steer healing
Min Zhao and colleagues show that the endogenous electric field at a wound directs cell migration through PI3K and PTEN signalling, and can override other cues.
Min ZhaoNature ↗ - 2006
A person controls a computer cursor with thought
In the BrainGate trial, a man with tetraplegia uses an implanted microelectrode array to control a computer cursor and open simulated email. This is an early demonstration of an implanted brain–computer interface.
2010s
- 2011
Tumor Treating Fields approved
The FDA approves alternating electric fields delivered through scalp electrodes for recurrent glioblastoma. Approval for newly diagnosed glioblastoma follows in 2015.
- 2012
Voltage patterns can induce eyes
In *Xenopus* embryos, imposing a specific membrane-voltage pattern with ion-channel misexpression induces eye-like structures in tissue far from the head. This is a widely cited example of voltage acting as a patterning signal.
Vaibhav Pai, Michael LevinDevelopment ↗ - 2012
Cable bacteria discovered
Filamentous bacteria are found to conduct electrons over centimetre distances through marine sediment, linking chemical reactions that happen far apart. They become a model system for biological conduction.
Christian Pfeffer, Lars Peter NielsenNature ↗ - 2015
Bacteria signal with ion waves
Bacterial biofilms are shown to coordinate metabolism with waves of potassium ions released through ion channels, a form of electrical signalling similar to that in neurons.
Arthur Prindle, Gürol SüelNature ↗ - 2017
Rewritten body plans persist in planaria
Briefly blocking gap junctions produces two-headed planarian flatworms that keep regenerating two heads in later rounds of amputation, without any genetic change. This is evidence that a bioelectric state can store anatomical information.
Fallon Durant, Michael LevinBiophysical Journal ↗ - 2018
Watching a plant's alarm signal travel
Real-time imaging shows that glutamate released at a wound triggers a fast calcium wave that travels through a plant's vasculature to distant leaves and switches on defences.
Masatsugu Toyota, Simon GilroyScience ↗ - 2019
Neurons form synapses with brain tumours
Two groups report in *Nature* that glioma cells receive synaptic input from neurons and that neural activity drives tumour growth, founding the field of cancer neuroscience.
Michelle Monje, Frank Winkler
2020s
- 2020
Xenobots
Computer-designed organisms built from frog skin and heart cells move, heal and work together, showing that unmodified cells can be arranged into new living forms.
Sam Kriegman, Douglas Blackiston, Michael Levin, Josh BongardRead our entry - 2022
Adult frogs regrow functional legs
A 24-hour treatment with a five-drug cocktail in a wearable bioreactor triggers more than a year of leg regrowth in adult *Xenopus*, which normally cannot regenerate limbs.
Nirosha Murugan, Michael Levin, David KaplanRead our entry - 2023
Brain–spine interface restores natural walking
A wireless "digital bridge" between brain implants and spinal cord stimulation lets a man with chronic tetraplegia stand, walk and climb stairs by thinking about moving.
Henri Lorach, Grégoire Courtine, Jocelyne BlochRead our entry - 2023
Speech neuroprostheses reach conversational rates
Two teams decode attempted speech from cortical implants in people with paralysis, producing text at 62 and 78 words per minute, as well as a synthesized voice and a digital avatar.
- 2023
Anthrobots from human cells
Adult human airway cells self-assemble into motile multicellular constructs that encourage neurons to grow over damaged areas in a lab dish.
Gizem Gumuskaya, Michael LevinRead our entry