Using Brain Stimulation to Increase Memory

In Aware: The Science and Practice of Presence, Daniel Siegel lists five major benefits of practicing the three learnable skills of meditation: focused attention, open awareness, and kind intention. The benefits are improved immune function, optimization of telomerase levels, reduced inflammation, improved cardiovascular factors such as blood pressure, and increased neural integration in the brain.

In a previous article, What is the Future of Aging?, I presented the results of an 11-year study that showed that seniors who meditated daily had lower LDL cholesterol, higher HDL cholesterol, were more efficient at removing toxins from the body, and had less inflammation. The main cause of aging is inflammation, a major contributor to all of the diseases that plague us. In what may become the canonical experiments in the art of aging, L. Frank Baum’s The Wonderful Wizard of Oz, included a test that identified the four qualities of a great leader: leadership is defined as “the ability to get things done”.

As the name suggests, focused attention is the ability to stay with what is in front of us and not get distracted by what is distracting us. In daily life, distraction is an issue. In the lab, distractions have been manipulated to determine how best to stimulate the hippocampus, a brain structure critical for memory. In one set of experiments, the hippocampus was stimulated using transcranial direct current stimulation (tDCS), which causes the skin to produce the contraction of the left motor cortex. When the left motor cortex is stimulated, it moves the eyelids and dilates the pupils. In another set of experiments, the left motor cortex was stimulated to cause the subject to remember a short-term memory, which was a picture of the eye and the name of the face. The subjects had difficulty in remembering the face and, of course, the eye was red. When the left motor cortex was stimulated to cause a memory, the subject correctly remembered both. The reason for this memory is that the left motor cortex is causing distraction in the subject’s attention.

In a more extreme manner, a different set of experiments was conducted in the lab, this time to induce the subject to experience fear. The subject is presented with a pair of pictures and told to press a button to indicate whether the picture looked like an owl or a cobra. (This is a very simple set of experiments but demonstrates the importance of attentional state in the initiation of fear.) After viewing the pictures, the subject is given a few seconds to either press a button indicating that the face in the picture looked like an owl or a button indicating that it looked like a cobra. The experimenters found that the subjects were able to make an incorrect identification 62% of the time even when they were shown the paired pictures while being transcranial stimulation to the left fusiform face area.

In addition, the electrodes were placed on the surface of the skin. (Again, this is not an uncommon procedure as it has been used in veterinary medicine for detecting fear or anxiety.) By placing the electrodes on the surface of the skin, the subjects were able to avoid the need to apply the electrodes to the brain. (This was also part of the reason that caused the dogs to show fear, as they were made to fear the left motor cortex.)

So the obvious question for the average person to ask is, why would scientists conduct studies if the results were already known. To answer this question, we need to understand the difference between a memory, and what the hippocampus is. A memory is formed by the deposition of a pattern of neurons in the dentate gyrus of the hippocampus. This is a region of the hippocampus that is responsible for long term memory. So it is the place where a long term memory is formed, at any one time.

The subjects in these experiments are looking at a screen which represents the face they are being shown. A pair of pictures are shown, one which looks like an owl and another which looks like a cobra. A button is pressed when the subject sees the owl. The subject is given just a few seconds to decide whether the pictured face is that of a cobra, or is it an owl. At the end of that time, a second button press is pressed, by the subject, to make the subject decide if it is the owl.

The subjects were told that they would be tested on their ability to decide what was the face of an animal after a series of button presses were shown. But they were told that they were not actually being given any tasks, or actual tasks.

The purpose of the study was to see if a direct application of transcranial direct current stimulation to the rodent hippocampus could prevent the subject from making a mistake, in being able to choose between seeing an owl or a cobra.

The study showed that the subjects experienced a reduction in their anxiety level when the subject could see the difference between the two pictures.

The study also showed that when the subjects saw the owl, the hippocampal neurons were more numerous. When the subjects saw the cobra, the number of hippocampal neurons was similar to that of a subject who had not seen either owl.

So how did this research benefit you? By improving the time you spend in the bathroom, it made you realize how much you hate the bathroom, so you spend less time in there, so your body will feel better.

This study has been used, as a way to help improve memory, to not forget where you put things. That you could place the objects you want to remember in a series of buttons, and transcranial direct current stimulation to the left and right hippocampi. The left and right hippocampi were involved with remembering what was previously seen, with the subjects being able to choose which hippocampi was stimulated when. When they were able to read the buttons out loud, they were able to recall the location of the objects better. They were not able to see which button on a particular row was actually stimulating which hippocampi, the order was irrelevant.

Another study involved a group of young adults who were asked to push a button when they saw an owl or a cobra, when they saw the owl, the hippocampus on the left side of the brain was stimulated, but when the subject saw the cobra, the stimulation was on the right side of the brain.

This research has shown that in young adults, when the subjects chose which side of the brain was stimulating, they experienced a reduction in anxiety, and a better memory for which hippocampus was stimulated.

The two categories, are not that different, from the way they act, what their brains are made up of, and what their memories are formed. We must also consider that the subjects of the studies were told that they were participating in an experiment, and were told to push a button when they saw an object.

These studies have shown that this type of system may well be very good at helping us remember where we put things, which could be very helpful in times of natural disasters, and other crises of life. But, we also have to think about the consequences of this kind of technology, for what it does to the subject. For every subject in these studies was told that they could stop any time they wanted to, and knew that they were able to go through with the experiment, if they wanted to.

How long does it take to have a positive reaction? For every subject that was trained, and told that they were experiencing a change, there were 20 or 30 subjects who were trained and told that they were having anxiety attacks. When it is the subjects who are experiencing the changes, rather than the subjects being able to stop the treatment, we should be very wary about the safety and value of these systems. I want to believe that these systems are safe. But, I want to know for sure.

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