Why the “You” in an Afterlife Wouldn’t Really Be You

July 23, 2017

The Discovery is a 2017 Netflix film in which Robert Redford plays a scientist who proves that the afterlife is real. “Once the body dies, some part of our consciousness leaves us and travels to a new plane,” the scientist explains, evidenced by his machine that measures, as another character puts it, “brain wavelengths on a subatomic level leaving the body after death.”

This idea is not too far afield from a real theory called quantum consciousness, proffered by a wide range of people, from physicist Roger Penrose to physician Deepak Chopra. Some versions hold that our mind is not strictly the product of our brain and that consciousness exists separately from material substance, so the death of your physical body is not the end of your conscious existence. Because this is the topic of my next book, Heavens on Earth: The Scientific Search for the Afterlife, Immortality, and Utopia (Henry Holt, 2018), the film triggered a number of problems I have identified with all such concepts, both scientific and religious.

First, there is the assumption that our identity is located in our memories, which are presumed to be permanently recorded in the brain: if they could be copied and pasted into a computer or duplicated and implanted into a resurrected body or soul, we would be restored. But that is not how memory works. Memory is not like a DVR that can play back the past on a screen in your mind. Memory is a continually edited and fluid process that utterly depends on the neurons in your brain being functional. It is true that when you go to sleep and wake up the next morning or go under anesthesia for surgery and come back hours later, your memories return, as they do even after so-called profound hypothermia and circulatory arrest. Under this procedure, a patient’s brain is cooled to as low as 50 degrees Fahrenheit, which causes electrical activity in neurons to stop—suggesting that long-term memories are stored statically. But that cannot happen if your brain dies. That is why CPR has to be done so soon after a heart attack or drowning—because if the brain is starved of oxygen-rich blood, the neurons die, along with the memories stored therein.

Second, there is the supposition that copying your brain’s connectome—the diagram of its neural connections—uploading it into a computer (as some scientists suggest) or resurrecting your physical self in an afterlife (as many religions envision) will result in you waking up as if from a long sleep either in a lab or in heaven. But a copy of your memories, your mind or even your soul is not you. It is a copy of you, no different than a twin, and no twin looks at his or her sibling and thinks, “There I am.” Neither duplication nor resurrection can instantiate you in another plane of existence.

Third, your unique identity is more than just your intact memories; it is also your personal point of view. Neuroscientist Kenneth Hayworth, a senior scientist at the Howard Hughes Medical Institute and president of the Brain Preservation Foundation, divided this entity into the MEMself and the POVself. He believes that if a complete MEMself is transferred into a computer (or, presumably, resurrected in heaven), the POVself will awaken. I disagree. If this were done without the death of the person, there would be two memory selves, each with its own POVself looking out at the world through its unique eyes. At that moment, each would take a different path in life, thereby recording different memories based on different experiences. “You” would not suddenly have two POVs. If you died, there is no known mechanism by which your POVself would be transported from your brain into a computer (or a resurrected body). A POV depends entirely on the continuity of self from one moment to the next, even if that continuity is broken by sleep or anesthesia. Death is a permanent break in continuity, and your personal POV cannot be moved from your brain into some other medium, here or in the hereafter.

If this sounds dispiriting, it is just the opposite. Awareness of our mortality is uplifting because it means that every moment, every day and every relationship matters. Engaging deeply with the world and with other sentient beings brings meaning and purpose. We are each of us unique in the world and in history, geographically and chronologically. Our genomes and connectomes cannot be duplicated, so we are individuals vouchsafed with awareness of our mortality and self-awareness of what that means. What does it mean? Life is not some temporary staging before the big show hereafter—it is our personal proscenium in the drama of the cosmos here and now.”

This article was originally published with the title “Who Are You?”

ABOUT THE AUTHOR(S)

Michael Shermer is publisher of Skeptic magazine (www.skeptic.com) and a Presidential Fellow at Chapman University. His next book is Heavens on Earth. Follow him on Twitter @michaelshermer

https://www.scientificamerican.com/article/why-the-ldquo-you-rdquo-in-an-afterlife-wouldnt-really-be-you/

IBM scientists achieve storage memory breakthrough

June 04, 2016

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For the first time, scientists at IBM Research have demonstrated reliably storing 3 bits of data per cell using a relatively new memory technology known as phase-change memory (PCM).

The current landscape spans from venerable DRAM to hard disk drives to ubiquitous flash. But in the last several years PCM has attracted the industry’s attention as a potential universal memory technology based on its combination of read/write speed, endurance, non-volatility and density. For example, PCM doesn’t lose data when powered off, unlike DRAM, and the technology can endure at least 10 million write cycles, compared to an average flash USB stick, which tops out at 3,000 write cycles.

This research breakthrough provides fast and easy storage to capture the exponential growth of data from mobile devices and the Internet of Things.

Applications

IBM scientists envision standalone PCM as well as hybrid applications, which combine PCM and flash storage together, with PCM as an extremely fast cache. For example, a mobile phone’s operating system could be stored in PCM, enabling the phone to launch in a few seconds. In the enterprise space, entire databases could be stored in PCM for blazing fast query processing for time-critical online applications, such as financial transactions.

Machine learning algorithms using large datasets will also see a speed boost by reducing the latency overhead when reading the data between iterations.

How PCM Works

PCM materials exhibit two stable states, the amorphous (without a clearly defined structure) and crystalline (with structure) phases, of low and high electrical conductivity, respectively.

To store a ‘0’ or a ‘1’, known as bits, on a PCM cell, a high or medium electrical current is applied to the material. A ‘0’ can be programmed to be written in the amorphous phase or a ‘1’ in the crystalline phase, or vice versa. Then to read the bit back, a low voltage is applied. This is how re-writable Blue-ray Discs store videos.

Previously scientists at IBM and other institutes have successfully demonstrated the ability to store 1 bit per cell in PCM, but today at the IEEE International Memory Workshop in Paris, IBM scientists are presenting, for the first time, successfully storing 3 bits per cell in a 64k-cell array at elevated temperatures and after 1 million endurance cycles.

“Phase change memory is the first instantiation of a universal memory with properties of both DRAM and flash, thus answering one of the grand challenges of our industry,” said Dr. Haris Pozidis, an author of the paper and the manager of non-volatile memory research at IBM Research – Zurich. “Reaching three bits per cell is a significant milestone because at this density the cost of PCM will be significantly less than DRAM and closer to flash.”

To achieve multi-bit storage IBM scientists have developed two innovative enabling technologies: a set of drift-immune cell-state metrics and drift-tolerant coding and detection schemes.

More specifically, the new cell-state metrics measure a physical property of the PCM cell that remains stable over time, and are thus insensitive to drift, which affects the stability of the cell’s electrical conductivity with time. To provide additional robustness of the stored data in a cell over ambient temperature fluctuations a novel coding and detection scheme is employed. This scheme adaptively modifies the level thresholds that are used to detect the cell’s stored data so that they follow variations due to temperature change. As a result, the cell state can be read reliably over long time periods after the memory is programmed, thus offering non-volatility.

“Combined these advancements address the key challenges of multi-bit PCM, including drift, variability, temperature sensitivity and endurance cycling,” said Dr. Evangelos Eleftheriou, IBM Fellow.

The experimental multi-bit PCM chip used by IBM scientists is connected to a standard integrated circuit board. The chip consists of a 2 × 2 Mcell array with a 4- bank interleaved architecture. The memory array size is 2 × 1000 μm × 800 μm. The PCM cells are based on doped-chalcogenide alloy and were integrated into the prototype chip serving as a characterization vehicle in 90 nm CMOS baseline technology.

More information: Aravinthan Athmanathan et al. Multilevel-Cell Phase-Change Memory: A Viable Technology, IEEE Journal on Emerging and Selected Topics in Circuits and Systems (2016). DOI: 10.1109/JETCAS.2016.2528598

M. Stanisavljevic, H. Pozidis, A. Athmanathan, N. Papandreou, T. Mittelholzer, and E. Eleftheriou,”Demonstration of Reliable Triple-Level-Cell (TLC) Phase-Change Memory,” in Proc. International Memory Workshop, Paris, France, May 16-18, 2016

Read more at: http://phys.org/news/2016-05-ibm-scientists-storage-memory-breakthrough.html#jCp

DARPA Project Starts Building Human Memory Prosthetics

September 6, 2014

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Photo: Lawrence Livermore National Laboratory

The first memory-enhancing devices could be implanted within four years

“They’re trying to do 20 years of research in 4 years,” says Michael Kahana in a tone that’s a mixture of excitement and disbelief. Kahana, director of the Computational Memory Lab at the University of Pennsylvania, is mulling over the tall order from the U.S. Defense Advanced Research Projects Agency (DARPA). In the next four years, he and other researchers are charged with understanding the neuroscience of memory and then building a prosthetic memory device that’s ready for implantation in a human brain.

DARPA’s first contracts under its Restoring Active Memory (RAM) program challenge two research groups to construct implants for veterans with traumatic brain injuries that have impaired their memories. Over 270,000 U.S. military service members have suffered such injuries since 2000, according to DARPA, and there are no truly effective drug treatments. This program builds on an earlier DARPA initiative focused on building a memory prosthesis, under which a different group of researchers had dramatic success in improving recall in mice and monkeys.

Kahana’s team will start by searching for biological markers of memory formation and retrieval. For this early research, the test subjects will be hospitalized epilepsy patients who have already had electrodes implanted to allow doctors to study their seizures. Kahana will record the electrical activity in these patients’ brains while they take memory tests.

“The memory is like a search engine,” Kahana says. “In the initial memory encoding, each event has to be tagged. Then in retrieval, you need to be able to search effectively using those tags.” He hopes to find the electric signals associated with these two operations.

Once they’ve found the signals, researchers will try amplifying them using sophisticated neural stimulation devices. Here Kahana is working with the medical device maker Medtronic, in Minneapolis, which has already developed one experimental implant that can both record neural activity and stimulate the brain. Researchers have long wanted such a “closed-loop” device, as it can use real-time signals from the brain to define the stimulation parameters.

Kahana notes that designing such closed-loop systems poses a major engineering challenge. Recording natural neural activity is difficult when stimulation introduces new electrical signals, so the device must have special circuitry that allows it to quickly switch between the two functions. What’s more, the recorded information must be interpreted with blistering speed so it can be translated into a stimulation command. “We need to take analyses that used to occupy a personal computer for several hours and boil them down to a 10-millisecond algorithm,” he says.

In four years’ time, Kahana hopes his team can show that such systems reliably improve memory in patients who are already undergoing brain surgery for epilepsy or Parkinson’s. That, he says, will lay the groundwork for future experiments in which medical researchers can try out the hardware in people with traumatic brain injuries—people who would not normally receive invasive neurosurgery.

The second research team is led by Itzhak Fried, director of the Cognitive Neurophysiology Laboratory at the University of California, Los Angeles. Fried’s team will focus on a part of the brain called the entorhinal cortex, which is the gateway to the hippocampus, the primary brain region associated with memory formation and storage. “Our approach to the RAM program is homing in on this circuit, which is really the golden circuit of memory,” Fried says. In a 2012 experiment, he showed that stimulating the entorhinal regions of patients while they were learning memory tasks improved their performance.

Fried’s group is working with Lawrence Livermore National Laboratory, in California, to develop more closed-loop hardware. At Livermore’s Center for Bioengineering, researchers are leveraging semiconductor manufacturing techniques to make tiny implantable systems. They first print microelectrodes on a polymer that sits atop a silicon wafer, then peel the polymer off and mold it into flexible cylinders about 1 millimeter in diameter. The memory prosthesis will have two of these cylindrical arrays, each studded with up to 64 hair-thin electrodes, which will be capable of both recording the activity of individual neurons and stimulating them. Fried believes his team’s device will be ready for tryout in patients with traumatic brain injuries within the four-year span of the RAM program.

Outside observers say the program’s goals are remarkably ambitious. Yet Steven Hyman, director of psychiatric research at the Broad Institute of MIT and Harvard, applauds its reach. “The kind of hardware that DARPA is interested in developing would be an extraordinary advance for the whole field,” he says. Hyman says DARPA’s funding for device development fills a gap in existing research. Pharmaceutical companies have found few new approaches to treating psychiatric and neurodegenerative disorders in recent years, he notes, and have therefore scaled back drug discovery efforts. “I think that approaches that involve devices and neuromodulation have greater near-term promise,” he says.

This article originally appeared in print as “Making a Human Memory Chip.”

http://spectrum.ieee.org/biomedical/bionics/darpa-project-starts-building-human-memory-prosthetics

DARPA taps Lawrence Livermore to develop world’s first neural device to restore memory

July 16, 2014
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The Department of Defense’s Defense Advanced Research Projects Agency (DARPA) awarded Lawrence Livermore National Laboratory (LLNL) up to $2.5 million to develop an implantable neural device with the ability to record and stimulate neurons within the brain to help restore memory, DARPA officials announced this week.

The research builds on the understanding that memory is a process in which neurons in certain regions of the brain encode information, store it and retrieve it. Certain types of illnesses and injuries, including Traumatic Brain Injury (TBI), Alzheimer’s disease and epilepsy, disrupt this process and cause memory loss. TBI, in particular, has affected 270,000 military service members since 2000.

The goal of LLNL’s work — driven by LLNL’s Neural Technology group and undertaken in collaboration with the University of California, Los Angeles (UCLA) and Medtronic — is to develop a device that uses real-time recording and closed-loop stimulation of neural tissues to bridge gaps in the injured brain and restore individuals’ ability to form new memories and access previously formed ones.

The research is funded by DARPA’s Restoring Active Memory (RAM) program.

Specifically, the Neural Technology group will seek to develop a neuromodulation system — a sophisticated electronics system to modulate neurons — that will investigate areas of the brain associated with memory to understand how new memories are formed. The device will be developed at LLNL’s Center for Bioengineering.

“Currently, there is no effective treatment for memory loss resulting from conditions like TBI,” said LLNL’s project leader Satinderpall Pannu, director of the LLNL’s Center for Bioengineering, a unique facility dedicated to fabricating biocompatible neural interfaces. “This is a tremendous opportunity from DARPA to leverage Lawrence Livermore’s advanced capabilities to develop cutting-edge medical devices that will change the health care landscape.”

LLNL will develop a miniature, wireless and chronically implantable neural device that will incorporate both single neuron and local field potential recordings into a closed-loop system to implant into TBI patients’ brains. The device — implanted into the entorhinal cortex and hippocampus — will allow for stimulation and recording from 64 channels located on a pair of high-density electrode arrays. The entorhinal cortex and hippocampus are regions of the brain associated with memory.

The arrays will connect to an implantable electronics package capable of wireless data and power telemetry. An external electronic system worn around the ear will store digital information associated with memory storage and retrieval and provide power telemetry to the implantable package using a custom RF-coil system.

Designed to last throughout the duration of treatment, the device’s electrodes will be integrated with electronics using advanced LLNL integration and 3D packaging technologies. The microelectrodes that are the heart of this device are embedded in a biocompatible, flexible polymer.

Using the Center for Bioengineering’s capabilities, Pannu and his team of engineers have achieved 25 patents and many publications during the last decade. The team’s goal is to build the new prototype device for clinical testing by 2017.

Lawrence Livermore’s collaborators, UCLA and Medtronic, will focus on conducting clinical trials and fabricating parts and components, respectively.

“The RAM program poses a formidable challenge reaching across multiple disciplines from basic brain research to medicine, computing and engineering,” said Itzhak Fried, lead investigator for the UCLA on this project andprofessor of neurosurgery and psychiatry and biobehavioral sciences at the David Geffen School of Medicine at UCLA and the Semel Institute for Neuroscience and Human Behavior. “But at the end of the day, it is the suffering individual, whether an injured member of the armed forces or a patient with Alzheimer’s disease, who is at the center of our thoughts and efforts.”

LLNL’s work on the Restoring Active Memory program supports President Obama’s Brain Research through Advancing Innovative Neurotechnologies (BRAIN) initiative.

“Our years of experience developing implantable microdevices, through projects funded by the Department of Energy (DOE), prepared us to respond to DARPA’s challenge,” said Lawrence Livermore Engineer Kedar Shah, a project leader in the Neural Technology group.


Story Source:

The above story is based on materials provided by DOE/Lawrence Livermore National Laboratory. Note: Materials may be edited for content and length.

How to erase a memory –- and restore it: Researchers reactivate memories in rats

June 2, 2014

Artist's rendering of nerve cells. Credit: © fotoliaxrender / Fotolia

Artist’s rendering of nerve cells.
Credit: © fotoliaxrender / Fotolia

Researchers at the University of California, San Diego School of Medicine have erased and reactivated memories in rats, profoundly altering the animals’ reaction to past events.

The study, published in the June 1 advanced online issue of the journal Nature, is the first to show the ability to selectively remove a memory and predictably reactivate it by stimulating nerves in the brain at frequencies that are known to weaken and strengthen the connections between nerve cells, called synapses.

“We can form a memory, erase that memory and we can reactivate it, at will, by applying a stimulus that selectively strengthens or weakens synaptic connections,” said Roberto Malinow, MD, PhD, professor of neurosciences and senior author of the study.

Scientists optically stimulated a group of nerves in a rat’s brain that had been genetically modified to make them sensitive to light, and simultaneously delivered an electrical shock to the animal’s foot. The rats soon learned to associate the optical nerve stimulation with pain and displayed fear behaviors when these nerves were stimulated.

Analyses showed chemical changes within the optically stimulated nerve synapses, indicative of synaptic strengthening.

In the next stage of the experiment, the research team demonstrated the ability to weaken this circuitry by stimulating the same nerves with a memory-erasing, low-frequency train of optical pulses. These rats subsequently no longer responded to the original nerve stimulation with fear, suggesting the pain-association memory had been erased.

In what may be the study’s most startlingly discovery, scientists found they could re-activate the lost memory by re-stimulating the same nerves with a memory-forming, high-frequency train of optical pulses. These re-conditioned rats once again responded to the original stimulation with fear, even though they had not had their feet re-shocked.

“We can cause an animal to have fear and then not have fear and then to have fear again by stimulating the nerves at frequencies that strengthen or weaken the synapses,” said Sadegh Nabavi, a postdoctoral researcher in the Malinow lab and the study’s lead author.

In terms of potential clinical applications, Malinow, who holds the Shiley Endowed Chair in Alzheimer’s Disease Research in Honor of Dr. Leon Thal, noted that the beta amyloid peptide that accumulates in the brains of people with Alzheimer’s disease weakens synaptic connections in much the same way that low-frequency stimulation erased memories in the rats. “Since our work shows we can reverse the processes that weaken synapses, we could potentially counteract some of the beta amyloid’s effects in Alzheimer’s patients,” he said.

Co-authors include Rocky Fox and Christophe Proulx, UCSD Department of Neurosciences; and John Lin and Roger Tsien, UCSD Department of Pharmacology.

This research was funded, in part, by the National Institutes of Health (grants MH049159 and NS27177) and Cure Alzheimer’s Fund.


Story Source:

The above story is based on materials provided by University of California, San Diego Health Sciences. Note: Materials may be edited for content and length.


Journal Reference:

  1. Sadegh Nabavi, Rocky Fox, Christophe D. Proulx, John Y. Lin, Roger Y. Tsien and Roberto Malinow. Engineering a memory with LTD and LTP. Nature, 2014 DOI: 10.1038/nature13294

A brain implant to restore memory

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The Defense Advanced Research Projects Agency (DARPA) is forging ahead with a four-year plan to build a sophisticated memory stimulator, as part of President Barack Obama’s $100 million initiative to better understand the human brain.

The science has never been done before, and raises ethical questions about whether the human mind should be manipulated in the name of staving off war injuries or managing the aging brain.
Some say those who could benefit include the five million Americans with Alzheimer’s disease and the nearly 300,000 US military men and women who have sustained traumatic brain injuries in Iraq and Afghanistan.

“If you have been injured in the line of duty and you can’t remember your family, we want to be able to restore those kinds of functions,” DARPA program manager Justin Sanchez said this week at a conference in the US capital convened by the Center for Brain Health at the University of Texas.

“We think that we can develop neuroprosthetic devices that can directly interface with the hippocampus, and can restore the first type of memories we are looking at, the declarative memories,” he said.
Declarative memories are recollections of people, events, facts and figures, and no research has ever shown they can be put back once they are lost.

Early days

What researchers have been able to do so far is help reduce tremors in people with Parkinson’s disease, cut back on seizures among epileptics and even boost memory in some Alzheimer’s patients through a process called deep brain stimulation.

Those devices were inspired by cardiac pacemakers, and pulse electricity into the brain much like a steady drum beat, but they don’t work for everyone.

Experts say a much more nuanced approach is needed when it comes to restoring memory.
“Memory is patterns and connections,” explained Robert Hampson, an associate professor at Wake Forest University.

“For us to come up with a memory prosthetic, we would actually have to have something that delivers specific patterns,” said Hampson, adding that he could not comment specifically on DARPA’s plans.

Hampson’s research on rodents and monkeys has shown that neurons in the hippocampus—the part of the brain that processes memory—fire differently when they see red or blue, or a picture of a face versus a type of food.

Equipped with this knowledge, Hampson and colleagues have been able to extend the animals’ short-term, working memory using brain prosthetics to stimulate the hippocampus.

They could coax a drugged monkey into performing closer to normal at a memory task, and confuse it by manipulating the signal so that it would choose the opposite image of what it remembered.
According to Hampson, to restore a human’s specific memory, scientists would have to know the precise pattern for that memory.

Instead, scientists in the field think they could improve a person’s memory by simply helping the brain work more like it used to before the injury.

“The idea is to restore a function back to normal or near normal of the memory processing areas of the brain so that the person can access their formed memories, and so that they can form new memories as needed,” Hampson said.

Ethical concerns

It’s easy to see how manipulating memories in people could open up an ethical minefield, said Arthur Caplan, a medical ethicist at New York University’s Langone Medical Center.

“When you fool around with the brain you are fooling around with personal identity,” said Caplan, who advises DARPA on matters of synthetic biology but not neuroscience.

“The cost of altering the mind is you risk losing sense of self, and that is a new kind of risk we never faced.”

When it comes to soldiers, the potential for erasing memories or inserting new ones could interfere with combat techniques, make warriors more violent and less conscientious, or even thwart investigations into war crimes, he said.

“If I could take a pill or put a helmet on and have some memories wiped out, maybe I don’t have to live with the consequences of what I do,” Caplan said.

DARPA’s website says that because its “programs push the leading edge of science,” the agency “periodically convenes scholars with expertise in these issues to discuss relevant ethical, legal, and social issues.”

Just who might be first in line for the experiments is another of the many unknowns.

Sanchez said the path forward will be formally announced in the next few months.

“We have got some of the most talented scientists in our country that will be working on this project. So stay tuned. Lots of exciting things will be coming in the very near future.”

Story Source:

The above story is based on materials provided by AFP, Kerry Sheridan.

http://bioengineer.org/coming-soon-brain-implant-restore-memory/

Neuroscientists: Brain activity may mark beginning of memories

April 14, 2014
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“This is like seeing the brain form memory traces in real time,” said Knierim, senior author of the research. “Seeing for the first time the brain creating a spatial firing field tied to a specific behavioral experience suggests that the map can be updated rapidly and robustly to lay down a memory of that experience.”

Using lab rats on a circular track, James Knierim, professor of neuroscience in the Zanvyl Krieger Mind/Brain Institute at Johns Hopkins, and a team of brain scientists noticed that the rats frequently paused to inspect their environment with head movements as they ran. The scientists found that this behavior activated a place cell in their brain, which helps the animal construct a cognitive map, a pattern of activity in the brain that reflects the animal’s internal representation of its environment.

In a paper recently published by the journal Nature Neuroscience, the researchers state that when the rodents passed that same area of the track seconds later, place cells fired again, a neural acknowledgement that the moment has imprinted itself in the brain’s cognitive map in the hippocampus.

The hippocampus is the brain’s warehouse for long- and short-term processing of episodic memories, such as memories of a specific experience like a trip to Maine or a recent dinner. What no one knew was what happens in the hippocampus the moment an experience imprints itself as a memory.

“This is like seeing the brain form memory traces in real time,” said Knierim, senior author of the research. “Seeing for the first time the brain creating a spatial firing field tied to a specific behavioral experience suggests that the map can be updated rapidly and robustly to lay down a memory of that experience.”

A place cell is a type of neuron within the hippocampus that becomes active when an animal or human enters a particular place in its environment. The activation of the cells helps create a spatial framework much like a map, that allows humans and animals to know where they are in any given location. Place cells can also act like neural flags that “mark” an experience on the map, like a pin that you drop on Google maps to mark the location of a restaurant.

“We believe that the spatial coordinates of the map are delivered to the hippocampus by one brain pathway, and the information about the things that populate the map, like the restaurant, are delivered by a separate pathway,” Knierim said. “When you experience a new item in the environment, the hippocampus combines these inputs to create a new spatial marker of that experience.”

In the experiments, researchers placed tiny wires in the brains of the rats to monitor when and where brain activity increased as they moved along the track in search of chocolate rewards. About every seven seconds, the rats stopped moving forward and turned their heads to the perimeter of the room as they investigated the different landmarks, behavior called “head-scanning.”

“We found that many cells that were previously silent would suddenly start firing during a specific head-scanning event,” Knierim said. “On the very next lap around the track, many of these cells had a brand new place field at that exact same location and this place field remained usually for the rest of the laps. We believe that this new place field marks the site of the head scan and allows the brain to form a memory of what it was that the rat experienced during the head scan.”

Knierim said the formation and stability of place fields and the newly activated place cells requires further study. The research is primarily intended to understand how memories are formed and retrieved under normal circumstances, but it could be applicable to learning more about people with brain trauma or hippocampal damage due to aging or Alzheimer’s.

“There are strong indications that humans and rats share the same spatial mapping functions of the hippocampus, and that these maps are intimately related to how we organize and store our memories of prior life events,” Knierim said. “Since the hippocampus and surrounding brain areas are the first parts of the brain affected in Alzheimer’s, we think that these studies may lend some insight into the severe memory loss that characterizes the early stages of this disease.”

http://www.sciencedaily.com/releases/2014/04/140414123513.htm