Introducing A Device that Can Stimulate Connection in Neuron-Like Cell
By Josh Nicolas
A biohybrid synapse with neurotransmitter-mediated plasticity
Scott T. Keene, Claudia Lubrano, Setareh Kazemzadeh, Armantas Melianas, Yaakov Tuchman, Giuseppina Polino, Paola Scognamiglio, Lucio Cinà, Alberto Salleo, Yoeri van de Burgt & Francesca Santoro
A group of researchers have successfully developed a device that uses artificial neurons, called neuromorphic devices, to study the plasticity of neuron connections. Based on the paper, this device can potentially be used to help repair chemical interaction between neurons.
First, the team should replicate the working mechanism of a real neuron. To realize this objective, the researchers use PC-12 cells, which originated from rats’ adrenal medulla, a tissue that has an important role in adrenalin release. It is known that this tissue is useful to generate neuron-like structures. Also, the team uses an electrode consisting of PEDOT-PSS, which is the abbreviation of poly ethylene dioxythiophene poly(styrene sulfonate). PEDOT PSS is a conducting polymer, and it is used as a receptor of neurotransmitters. Following is the chemical structure of PEDOT-PSS.
The researchers also use a microfluidic pump. The pump’s function is to release the neurotransmitter that has entered the receptor. This is because, in a biological neuron, the neurotransmitter binding to the receptor is reversible. To imitate this behaviour, the microfluidic channel made from polydimethylsiloxane (PDMS) is added. It can recycle the oxidized dopamine (dopamine o-quinone) and the dopamine that has entered the receptor. Following is the arrangement of the apparatus.
It is discovered that dopamine exocytosis by PC-12 cells induced by the postsynaptic voltage (Vpost) can increase the conductivity of the synaptic cleft, meaning that the signal from the presynaptic neuron is modulated. It is because dopamine oxidation occurs in the synaptic cleft. When oxidation occurs, the electron is released and thus increases the conductivity.
The long-term modulation effect can only be achieved when the neurotransmitter exists. There is only a short-term modulation when the team uses culture media (in the absence of dopamine and PC-12 cells). This result supports the Hebbian learning rule (neurons that fire together, wire together).
This success is a stepping stone for further development of ANN (Artificial Neural Network) devices that have been used for brain research, such as Brain Machine Interfaces. Hopefully we might have a device that can directly interact with our brain cells. See you in the next article!
