Syn, hjerneskader og tankelæsning

Igennem de sidste år har forskning i vores syn og hvordan den visuelle sansning er forbundet til hjernen skabt store udviklinger i forhold personer der på den ene eller anden måde lider af et synshandicap. I artiklen Wireless Vision Implant: Implantable Prosthesis Lets Patients Perceive Visual Images fortælles vi om mulige proteser i forbindelse med at give blinde, der lider af en sygdom i retina (se billedet nedenfor) et syn.

About 30 million people around the world have grown legally blind due to retinal diseases. The EPI-RET project has sought for a technical solution for the past twelve years to help these patients. This work has resulted in a unique system – a fully implantable visual prosthesis.
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A milestone was reached when the prosthetic system finally operated wirelessly and remotely controlled,” explains Dr. Ingo Krisch. “A great deal of detailed work was necessary before the implant could be activated without any external cable connections.”

“The designs became smaller and smaller, the materials more flexible, more robust and higher in performance, so that the implant now fits comfortably in the eye,” reports Michael Görtz. The system benefits from a particular disease pattern, and it uses a specific operating principle to restore sight: Suffering from retinitis pigmentosa, the light sensitive cells are destroyed, but the connection of the nerve cells to the brain remains intact.

The scientists have bypassed the defects of the retina by means of a visual prosthesis. The complete system comprises the implant and an external transmitter integrated in a spectacle-frame. The implant system converts the image patterns into interpretable stimulation signals. Data and energy are transferred to the implant by a telemetric link. The nerve cells inside the eye are then stimulated according to the captured images. Those intact cells are innervated by means of three-dimensional stimulation electrodes that rest against the retina like small studs.

Andre relevante artikler: Restoring Sight, One Pixel At A Time, Researchers Begin Tests On Next Generation Of Retinal Implant, Long-term Retinal Implant Study Offers Hope For Treating Blindness, Vision Partially Restored In Blind Mice.

Stamceller kan bruges i udbedringen af hjerneskader
 
I et andet område finder vi i artiklen New Stem Cell Therapy May Aid The Repair Of Damaged Brains. Stamceller menes at kunne blive brugt i mange forskellige sammenhænge, hvis vi altså formår at kontrollere udviklingen i cellerne.

According to some experts, newly born neuronal stem cells in the adult brain may provide a therapy for brain injury. But if these stem cells are to be utilized in this way, the process by which they are created, neurogenesis, must be regulated.
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According to the research, neurogenesis can be regulated through induced hypothermia. In rat subjects, a mild decrease in body temperature was found to substantially decrease the proliferation of newly-born neurons, a discovery that marks a major step forward for the development of neuronal stem cell-based brain therapies.

Since the 1930s, brain damage from stroke, head injury, near drowning and cardiac arrest was considered to be permanent because of a lack of repair mechanisms like other parts of the body. However, discovery of neuronal stem cells in the adult brain challenges that belief.

“Many questions remain before we adequately understand how to control these cells to repair a damaged brain,” says Katz. “However, the findings represent an important step in demonstrating that these cells can be controlled by simple external forces like hypothermia.”

Andre relevante artikler: Stem-cell Therapies For Brain More Complicated Than Thought, Stem Cell Treatment Succeeds In Spinal Cord-injured Rats

Tankelæsning ved algoritmer

Forskere er meget uenige om hvilke udsigter der er til en eventuel tankelæsning. Og argumenterne for og imod beror på forskellige elementer; nogen mener ikke det vil være til at måle, andre mener godt det vil være til at måle, men er skeptisk i forhold til om vi kan udvikle teknologi til at gøre det. I mellemtiden forsker nogen i det. I Neuroscientists Take Important Step toward Mind Reading har vi en indgangsvinkel til det.

Neuroscientist Kendrick Kay and his colleagues at the University of California, Berkeley, were able to successfully determine which of a large group of never-before-seen photographs a subject was viewing based purely on functional MRI data. By analyzing fMRI scans of viewers as they looked at thousands of images, Kay’s team created a computer model that uses picture elements such as angles and brightness to predict the neural activity elicited by a novel black-and-white photograph. Then the researchers scanned subjects while showing them new snapshots. Most of the time Kay’s model could single out which image the subject was viewing by matching its prediction of brain activity to the actual activity measured by the fMRI scanner, although very similar pictures tended to baffle the program.
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As for truly reading people’s thoughts, Kay does not foresee anything of that nature in this century. Technological improvement, he explains, may yield piles of brain data. Without sufficient insight into the brain’s workings, however, we will have no idea what it all means.

~ af sorensvendsen på juni 1, 2008.