Optogenetics: New Technology to Manipulate Memories


Optogenetics is a new technology that is being used to manipulate memories in rats. Neuroscientists have been very interested in studying how and where memories are created and placed since the beginning of modern science. The old idea was that a particular memory was situated in a cell. For example, one’s memory of a grandmother was in a cell, and if they experimentally stimulated that cell, the person would remember and think about their grandmother. A more recent idea, which resulted from the development of brain imaging techniques, is that memories are represented in the brain as patterns of neural circuitry activation. A long-standing idea is that memory formation is related to strengthening of the synaptic connections between neurons, which are the connections between the cells of the brain.

Dr. Roberto Manilow, a neuroscientist at the University of California – San Diego, is the lead scientist that developed optogenetics as a new technology for manipulating memories in rats. Optogenetics combines optics and genetics. Microbial opsin genes are used that code for an opsin protein that responds to light. These genes are inserted into cells in a chosen place in the brain and optical equipment that can either transmit or read light is inserted as well. The inserted optics are then used to send light signals to the opsin and control events in the cells. Light signals to the opsins in neurons can control the cell activities and cell to cell connections, that is, their synaptic connections.

The experiments that were done with rats showed that the optogenetic system could be used to make and erase memories. The rats were first conditioned using traditional methods of pairing a painful shock with a tone. Then when the tone was presented alone, the rat froze because it expected to receive a painful shock. The memory was created that the tone meant pain was coming. The research team then learned how to vary the optogenetic light signals to the brain to strengthen the neuronal synaptic connections or weaken them, thereby strengthening or erasing the memory of the tone/pain relation.

Manilow has suggested that this new optogenetic technique could be used in humans and may be beneficial in the treatment of many devastating diseases. In post-traumatic stress disorder (PTSD), people are traumatized in stressful situations and the memories of these experiences can then re-activate the trauma. Manilow believes that the optogenetic technique could be used to erase the memories of the traumatic experience. Alzheimer’s disease involves loss of memory and weakened synapses have been associated with this disease. Manilow suggested that optogenetics offers a way to intervene in the process of weakening synapses with Alzheimer’s disease.

While the possibilities for creating good with the new technology seem exciting in this early stage of development, further contemplation about the potential use of this new technology leads to chilling thoughts. What horrors could be produced by people manipulating memories with the push of a button that flashes light into the brain? Manchurian candidate possibilities are the first to come to mind. Other horrible things that could be done to people with this kind of manipulation of the brain will not even be mentioned here, for fear of the power of suggestion.

If this optogenetic technology were to come into use for Alzheimer’s disease or PTSD, who would be responsible for pressing the button to activate the light going into the brain? Who would decide which memories to keep and which to erase? Optogenetics as a new technology to manipulate memories needs to be in the hands of the right people.

Opinion by Margaret Lutze

Scientific American
Medical News Today

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