Scientific American Mind Article

The topic of my Scientific American article from the Mind deals with memory loss. In the article Recovering Lost Memory by Karl Peter Giese, this scientist refers to the neurodegenerative disease called Alzheimer's. Giese tells us that Alzheimer's disease is one in which there is an extensive loss of neurons in the brain which in turn destroys the memory's of that person. He goes on to describe a study done by Andre Fischer that shows neuron loss can be recovered, though neuron loss is irreversible.

It has been believed by scientists for a long time that memories lost cannot be recovered. In the article by Fischer described by Giese, memory loss may not be permanent. Environmental enrichment was used in the study by Fischer, using the model subject of mice. Genetically modified mice were used. These mice produced p25, a protein that does not occur normally but instead is formed as a result of Alzheimer's, terming it pathological. It is seen that the brain compensates for memory deficiency by actually producing this protein It was found to over activate an enzyme which regulated the function of other proteins. The protein, p25, can have opposite effects. If there are low levels in the brain, then beneficial effects on memory are seen, but if the brain produces high levels of p25, neuron death is inevitable. In order to examine therapy for memory loss, Fischer and his colleagues used the negative aspects of p25 to kill neurons in mice.

In these mice, the scientists selectively activated p25 which erased their memories in relation to tasks learned. There were two memory tests the mice underwent. The first involved a water maze in which they had to locate a submerged platform and the mice, in the second task, had to associate a particular environment with what they called a "mild foot shock." Both of these tasks involved the hippocampus which is a part of the brain critical to memory and profoundly affected by Alzheimer's. The researchers then provoked the fabrication of p25 to destroy greater than half of the hippocampal neurons. After testing the mice after killing their neurons, Fischer stated the memories had disappeared.

The second part of the experiment included environmental enrichment in which the mice ran on wheels and objects that would be found in a cage in a normal home. The enrichment did not replace the neurons lost but multiplied the connections between the happocampal neurons remaining. The mice were then able to compensate for the neurons that were lost by increasing the p25 levels and allowed for memory retrieval.

Fischer and his colleagues found a chemical that imitated environmental enrichment. Protein function that regulates gene activity can be moderated by environmental enrichment. Histone deacetylase (HDAC) which is blocked by this unknown chemical, impacts gene activity and this blocker could lead to the recovery of lost memories.

Based on this research, drug therapies can now be made that target HDAC enabling memories to be recovered. Though this and p25 are only a few suppliers of Alzheimer's disease, other studies with different models are needed in order to establish whether the HDAC blocker can actually recover memories. This will also lead scientists and doctors to understanding the storage and retrieval of memories. Fischer and his partners launched a great finding: connections are more important than numbers, in terms of neurons.