Posts tagged neuroscience
Articles and news from the latest research reports.
Memory Implants
A maverick neuroscientist believes he has deciphered the code by which the brain forms long-term memories.
Theodore Berger, a biomedical engineer and neuroscientist at the University of Southern California in Los Angeles, envisions a day in the not too distant future when a patient with severe memory loss can get help from an electronic implant. In people whose brains have suffered damage from Alzheimer’s, stroke, or injury, disrupted neuronal networks often prevent long-term memories from forming. For more than two decades, Berger has designed silicon chips to mimic the signal processing that those neurons do when they’re functioning properly—the work that allows us to recall experiences and knowledge for more than a minute. Ultimately, Berger wants to restore the ability to create long-term memories by implanting chips like these in the brain.
The idea is so audacious and so far outside the mainstream of neuroscience that many of his colleagues, says Berger, think of him as being just this side of crazy. “They told me I was nuts a long time ago,” he says with a laugh, sitting in a conference room that abuts one of his labs. But given the success of recent experiments carried out by his group and several close collaborators, Berger is shedding the loony label and increasingly taking on the role of a visionary pioneer.
Berger and his research partners have yet to conduct human tests of their neural prostheses, but their experiments show how a silicon chip externally connected to rat and monkey brains by electrodes can process information just like actual neurons. “We’re not putting individual memories back into the brain,” he says. “We’re putting in the capacity to generate memories.” In an impressive experiment published last fall, Berger and his coworkers demonstrated that they could also help monkeys retrieve long-term memories from a part of the brain that stores them.
If a memory implant sounds farfetched, Berger points to other recent successes in neuroprosthetics. Cochlear implants now help more than 200,000 deaf people hear by converting sound into electrical signals and sending them to the auditory nerve. Meanwhile, early experiments have shown that implanted electrodes can allow paralyzed people to move robotic arms with their thoughts. Other researchers have had preliminary success with artificial retinas in blind people.
Still, restoring a form of cognition in the brain is far more difficult than any of those achievements. Berger has spent much of the past 35 years trying to understand fundamental questions about the behavior of neurons in the hippocampus, a part of the brain known to be involved in forming memory. “It’s very clear,” he says. “The hippocampus makes short-term memories into long-term memories.”
What has been anything but clear is how the hippocampus accomplishes this complicated feat. Berger has developed mathematical theorems that describe how electrical signals move through the neurons of the hippocampus to form a long-term memory, and he has proved that his equations match reality. “You don’t have to do everything the brain does, but can you mimic at least some of the things the real brain does?” he asks. “Can you model it and put it into a device? Can you get that device to work in any brain? It’s those three things that lead people to think I’m crazy. They just think it’s too hard.”
Psychopaths are not neurally equipped to have concern for others
Prisoners who are psychopaths lack the basic neurophysiological “hardwiring” that enables them to care for others, according to a new study by neuroscientists at the University of Chicago and the University of New Mexico.
“A marked lack of empathy is a hallmark characteristic of individuals with psychopathy,” said the lead author of the study, Jean Decety, the Irving B. Harris Professor in Psychology and Psychiatry at UChicago. Psychopathy affects approximately 1 percent of the United States general population and 20 percent to 30 percent of the male and female U.S. prison population. Relative to non-psychopathic criminals, psychopaths are responsible for a disproportionate amount of repetitive crime and violence in society.
“This is the first time that neural processes associated with empathic processing have been directly examined in individuals with psychopathy, especially in response to the perception of other people in pain or distress,” he added.
The results of the study, which could help clinical psychologists design better treatment programs for psychopaths, are published in the article, “Brain Responses to Empathy-Eliciting Scenarios Involving Pain in Incarcerated Individuals with Psychopathy,” which appears online April 24 in the journal JAMA Psychiatry.
Joining Decety in the study were Laurie Skelly, a graduate student at UChicago; and Kent Kiehl, professor of psychology at the University of New Mexico.
For the study, the research team tested 80 prisoners between ages 18 and 50 at a correctional facility. The men volunteered for the test and were tested for levels of psychopathy using standard measures.
They were then studied with functional MRI technology, to determine their responses to a series of scenarios depicting people being intentionally hurt. They were also tested on their responses to seeing short videos of facial expressions showing pain.
The participants in the high psychopathy group exhibited significantly less activation in the ventromedial prefrontal cortex, lateral orbitofrontal cortex, amygdala and periaqueductal gray parts of the brain, but more activity in the striatum and the insula when compared to control participants, the study found.
The high response in the insula in psychopaths was an unexpected finding, as this region is critically involved in emotion and somatic resonance. Conversely, the diminished response in the ventromedial prefrontal cortex and amygdala is consistent with the affective neuroscience literature on psychopathy. This latter region is important for monitoring ongoing behavior, estimating consequences and incorporating emotional learning into moral decision-making, and plays a fundamental role in empathic concern and valuing the well-being of others.
“The neural response to distress of others such as pain is thought to reflect an aversive response in the observer that may act as a trigger to inhibit aggression or prompt motivation to help,” the authors write in the paper.
“Hence, examining the neural response of individuals with psychopathy as they view others being harmed or expressing pain is an effective probe into the neural processes underlying affective and empathy deficits in psychopathy,” the authors wrote.
Decety is one of the world’s leading experts on the biological underpinnings of empathy. His work also focuses on the development of empathy and morality in children.
Neurodegenerative and central nervous system (CNS) diseases represent a major public health issue affecting at least 20 million children and adults in the United States alone. Multiple drugs exist to treat and potentially cure these debilitating diseases, but 98 percent of all potential pharmaceutical agents are prevented from reaching the CNS directly due to the blood-brain barrier.
Using mucosa, or the lining of the nose, researchers in the department of Otology and Laryngology at the Massachusetts Eye and Ear/Harvard Medical School and the Biomedical Engineering Department of Boston University have demonstrated what may be the first known method to permanently bypass the blood-brain barrier, thus opening the door to new treatment options for those with neurodegenerative and CNS disease. Their study is published on PLOS ONE.
Many attempts have been made to deliver drugs across the blood-brain barrier using methods such as osmotic disruption and implantation of catheters into the brain; however these methods are temporary and prone to infection and dislodgement.
"As an endoscopic skull base surgeon, I and many other researchers have helped to develop methods to reconstruct large defects between the nose and brain using the patient’s own mucosa or nasal lining," said Benjamin S. Bleier, M.D., Otolaryngologist at Mass. Eye and Ear and HMS Assistant Professor.
Study co-author Xue Han, Ph.D., an assistant professor of Biomedical Engineering at Boston University, said, “The development of this model enables us to perform critical preclinical testing of novel therapies for neurological and psychiatric diseases.”
Inspired by recent advances in human endoscopic transnasal skull based surgical techniques, the investigators went to work to develop an animal model of this technique and use it to evaluate transmucosal permeability for the purpose of direct drug delivery to the brain.
In this study using a mouse model, researchers describe a novel method of creating a semi-permeable window in the blood-brain barrier using purely autologous tissues to allow for higher molecular weight drug delivery to the CNS. They demonstrated for the first time that these membranes are capable of delivering molecules to the brain which are up to 1,000-times larger than those excluded by the blood-brain barrier.
"Since this is a proven surgical technique which is known to be safe and well tolerated, this data suggests that these membranes may represent the first known method to permanently bypass the blood-brain barrier using the patient’s own tissue," Dr. Bleier said. "This method may open the door for the development of a variety of new therapies for neurodegenerative and CNS disease.
Future studies will be directed towards developing clinical trials to test this method in patients who have already undergone these endoscopic surgeries.”
(Image: iStockphoto)
After Brain Injury, New Astrocytes Play Unexpected Role in Healing
The production of a certain kind of brain cell that had been considered an impediment to healing may actually be needed to staunch bleeding and promote repair after a stroke or head trauma, researchers at Duke Medicine report.
These cells, known as astrocytes, can be produced from stem cells in the brain after injury. They migrate to the site of damage where they are much more effective in promoting recovery than previously thought. This insight from studies in mice, reported online April 24, 2013, in the journal Nature, may help researchers develop treatments that foster brain repair.
“The injury recovery process is complex,” said senior author Chay T. Kuo, M.D., PhD, George W. Brumley Assistant Professor of Cell Biology, Pediatrics and Neurobiology at Duke University. “There is a lot of interest in how new neurons can stimulate functional recovery, but if you make neurons without stopping the bleeding, the neurons don’t even get a chance. The brain somehow knows this, so we believe that’s why it produces these unique astrocytes in response to injury.”
Each year, more than 1.7 million people in the United States suffer a traumatic brain injury, according to the Centers for Disease Control and Prevention. Another 795,000 people a year suffer a stroke. Few therapies are available to treat the damage that often results from such injuries.
Kuo and colleagues at Duke are interested in replacing lost neurons after a brain injury as a way to restore function. Once damaged, mature neurons cannot multiply, so most research efforts have focused on inducing brain stem cells to produce more immature neurons to replace them.
This strategy has proved difficult, because in addition to making neurons, neural stem cells also produce astrocytes and oligodendrocytes, known as glial cells. Although glial cells are important for maintaining the normal function of neurons in the brain, the increased production of astrocytes from neural stem cell has been considered an unwanted byproduct, causing more harm than good. Proliferating astrocytes secrete proteins that can induce tissue inflammation and undergo gene mutations that can lead to aggressive brain tumors.
In their study of mice, the Duke team found an unexpected insight about the astrocytes produced from stem cells after injury. Stem cells live in a special area or “niche” in the postnatal/adult brain called the subventricular zone, and churn out neurons and glia in the right proportions based on cues from the surrounding tissue.
After an injury, however, the subventricular niche pumps out more astrocytes. Significantly, the Duke team found they are different from astrocytes produced in most other regions of the brain. These cells make their way to the injured area to help make an organized scar, which stops the bleeding and allows tissue recovery.
When the generation of these astrocytes in the subventricular niche was experimentally blocked after a brain injury, hemorrhaging occurred around the injured areas and the region did not heal. Kuo said the finding was made possible by insights about astrocytes from Cagla Eroglu, PhD, whose laboratory next door to Kuo’s conducts research on astrocyte interactions with neurons.
“Cagla and I started at Duke together and have known each other since our postdoctoral days,” Kuo said. “To have these stem cell-made astrocytes express a unique protein that Cagla understands more than anyone else, it’s just a wonderful example of scientific serendipity and collaboration.”
Additionally, Kuo said first author Eric J. Benner, M.D., PhD, a former postdoctoral fellow who now has his own laboratory at Duke, provided key clinical correlations on brain injury as a physician-scientist and practicing neonatologist in the Jean and George Brumley Jr. Neonatal-Perinatal Research Institute.
“We are very excited about this innate flexibility in neural stem cell behavior to know just what to do to help the brain after injury,” Kuo said. “Since bleeding in the brain after injury is a common and serious problem for patients, further research into this area may lead to effective therapies for accelerated brain recovery after injury.”
Mild Blast Injury Causes Molecular Changes in Brain Akin to Alzheimer’s Disease
A multicenter study led by scientists at the University of Pittsburgh School of Medicine shows that mild traumatic brain injury after blast exposure produces inflammation, oxidative stress and gene activation patterns akin to disorders of memory processing such as Alzheimer’s disease. Their findings were recently reported in the online version of the Journal of Neurotrauma.
Blast-induced traumatic brain injury (TBI) has become an important issue in combat casualty care, said senior investigator Patrick Kochanek, M.D., professor and vice chair of critical care medicine and director of the Safar Center for Resuscitation Research at Pitt. In many cases of mild TBI, MRI scans and other conventional imaging technology do not show overt damage to the brain.
“Our research reveals that despite the lack of a lot of obvious neuronal death, there is a lot of molecular madness going on in the brain after a blast exposure,” Dr. Kochanek said. “Even subtle injuries resulted in significant alterations of brain chemistry.”
The research team developed a rat model to examine whether mild blast exposure in a device called a shock tube caused any changes in the brain even if there was no indication of direct cell death, such as bleeding. Brain tissues of rats exposed to blast and to a sham procedure were tested two and 24 hours after the injury.
Gene activity patterns, which shifted over time, resembled patterns seen in neurodegenerative diseases, particularly Alzheimer’s, Dr. Kochanek noted. Markers of inflammation and oxidative stress, which reflects disruptions of cell signaling, were elevated, but there was no indication of energy failure that would be seen with poor tissue oxygenation.
“It appears that although the neurons don’t die after a mild injury, they do sustain damage,” he said. “It remains to be seen what multiple exposures, meaning repeat concussions, do to the brain over the long term.”
(Source: upmc.com)
Researchers from the Perelman School of Medicine at the University of Pennsylvania have shown that an area of the brain that initiates behavioral changes had greater activation in smokers who watched anti-smoking ads with strong arguments versus those with weaker ones, and irrespective of flashy elements, like bright and rapidly changing scenes, loud sounds and unexpected scenario twists. Those smokers also had significantly less nicotine metabolites in their urine when tested a month after viewing those ads, the team reports in a new study published online April 23 in the Journal of Neuroscience.
This is the first time research has shown an association between cognition and brain activity in response to content and format in televised ads and behavior.
In a study of 71 non-treatment-seeking smokers recruited from the Philadelphia area, the team, led by Daniel D. Langleben, M.D., a psychiatrist in the Center for Studies of Addiction at Penn Medicine, identified key brain regions engaged in the processing of persuasive communications using fMRI, or functional magnetic resonance imaging. They found that a part of the brain involved in future behavioral changes—known as the dorsomedial prefrontal cortex (dMPFC)—had greater activation when smokers watched an anti-smoking ad with a strong argument versus a weak one.
One month after subjects watched the ads, the researchers sampled smokers’ urine cotinine levels (metabolite of nicotine) and found that those who watched the strong ads had significantly less cotinine in their urine compared to their baseline versus those who watched weaker ads.
Even ads riddled with attention-grabbing tactics, the research suggests, are not effective at reducing tobacco intake unless their arguments are strong. However, ads with flashy editing and strong arguments, for example, produced better recognition.
“We investigated the two major dimensions of any piece of media, content and format, which are both important here,” said Dr. Langleben, who is also an associate professor in the department of Psychiatry. “If you give someone an unconvincing ad, it doesn’t matter what format you do on top of that. You can make it sensational. But in terms of effectiveness, content is more important. You’re better off adding in more sophisticated editing and other special effects only if it is persuasive.”
The paper may enable improved methods of design and evaluation of public health advertising, according to the authors, including first author An-Li Wang, PhD, of the Annenberg Public Policy Center at the University of Pennsylvania. And it could ultimately influence how producers shape the way ads are constructed, and how ad production budgets are allocated, considering special effects are expensive endeavors versus hiring screenwriters.
A 2009 study by Dr. Langleben and colleagues that looked solely at format found people were more likely to remember low-key, anti-smoking messages versus attention-grabbing messages. This was the first research to show that low-key versus attention-grabbing ads stimulated different patterns of activity, particularly in the frontal cortex and temporal cortex. But it did not address content strength or behavioral changes.
This new study is the first longitudinal investigation of the cognitive, behavioral, and neurophysical response to the content and format of televised anti-smoking ads, according to the authors.
“This sets the stage for science-based evaluation and design of persuasive public health advertising,” said Dr. Langleben. “An ad is only as strong as its central argument, which matters more than its audiovisual presentation. Future work should consider supplementing focus groups with more technology-heavy assessments, such as brain responses to these ads, in advance of even putting the ad together in its entirety.”
Alzheimer’s Researchers Creating “Designer Tracker” to Quantify Elusive Brain Protein, Provide Earlier Diagnosis
One of the biggest challenges with Alzheimer’s disease (AD) is that by the time physicians can detect behavioral changes, the disease has already begun its irreversibly destructive course. Scientists know toxic brain lesions created by amyloid beta and tau proteins are involved. Yet, emerging therapies targeting these lesions have failed in recent clinical trials. These findings suggest that successful treatments will require diagnosis of disease at its earliest stages.
Now, by using computer-aided drug discovery, an Ohio State University molecular biochemist and molecular imaging chemist are collaborating to create an imaging chemical that attaches predominantly to tau-bearing lesions in living brain. Their hope is that the “designer” tracer will open the door for earlier diagnosis – and better treatments for Alzheimer’s, frontal temporal dementia and traumatic brain injuries like those suffered by professional athletes, all conditions in which tangled tau filaments accumulate in brain tissue.
“We’re creating agents that are specifically engineered to bind the surface of aggregated tau proteins so that we can see where and how much tau is collecting in the brain,” said Jeff Kuret, professor of molecular and cellular biochemistry at The Ohio State University College of Medicine. “We think the “tau signature” can be used to improve diagnosis and staging of disease.”
The study’s co-investigator, Michael Tweedle, a professor of radiology at Ohio State’s College of Medicine, notes that there may be more advantages to being able to image tau.
“Unlike beta amyloid, tau appears in specific brain regions in Alzheimer’s,” said Tweedle. “With a better view of how tau is distinct from amyloid, we’ll be able to create a much more accurate view of disease staging, and do a much better job getting the right therapeutics into the right populations at the right time.”
Tweedle notes that there are no drugs currently available that target tau, but that several are in development. Both investigators emphasized that being able to image tau in a living brain could be critical for identifying individuals that could benefit from tau-tackling drugs as they move into clinical trials.
The search for tau selective neuroimaging agents is proceeding with the help of a pilot grant awarded to the team by Ohio State’s Center for Clinical and Translational Science (CCTS). The award provided them with the funds needed to synthesize candidate radiotracers for testing. The team then received funding from the Alzheimer’s Drug Discovery Foundation to test how the compounds distribute throughout the body. This work also leverages several CCTS-funded core resources. So far, the team has prepared 12 ligands that have promising binding affinity for tau aggregates.
“It’s an iterative process, and each step gives us new information on what we need to be looking for,” said Tweedle. “Now we know what parts of the molecule to alter while trying to retain other good qualities.”
Tauopathies are neurodegenerative diseases associated with the accumulation of tau protein “tangles” in the human brain. Alzheimer’s disease is one of the most common tauopathies, but tau aggregates are also found in certain forms of frontal temporal dementia as well as traumatic brain injuries. Alzheimer’s disease has become one of the most common disorders in the aging population, and is predicted to be a major driver of health care costs in the coming decades.
(Source: newswise.com)
Brain Scans Reveal That Humans Definitely Feel Empathy For Robots
While creating an empathetic robot is a long-held dream, understanding whether humans genuinely empathise with robots should — in theory — be easier. Now, a team of scientists have analysed fMRI brain scans to reveal that humans have similar brain function when shown affection and violence being inflicted on both humans and robots.
The experiments, conducted at the University of Duisburg, Essen, had 40 participants sit and watch videos of a small dinosaur-shaped robot. It was either treated in an affectionate or violent way, and then researchers measured physiological arousal — finding overwhelmingly strong reaction to the scenes of violence. A second study used functional magnetic-resonance imaging, and shows that affectionate interaction towards both robots and humans resulted in similar neural activation patterns in the brain.
That suggests that those actions elicit similar reactions for interactions with both humans and robots. The problem with most experiments on this subject is that participants generally choose not to report emotional reaction to robots — an fMRI scan gets around that problem. Rosenthal-von der Pütten, one of the researchers, explains the implications of the findings:
“One goal of current robotics research is to develop robotic companions that establish a long-term relationship with a human user, because robot companions can be useful and beneficial tools. They could assist elderly people in daily tasks and enable them to live longer autonomously in their homes, help disabled people in their environments, or keep patients engaged during the rehabilitation process. A common problem is that a new technology is exciting at the beginning, but this effect wears off especially when it comes to tasks like boring and repetitive exercise in rehabilitation. The development and implementation of uniquely humanlike abilities in robots like theory of mind, emotion and empathy is considered to have the potential to solve this dilemma.”
The scientists present their findings at the 63rd Annual International Communication Association conference in London in June.
Atrophy in key region of brain associated with multiple sclerosis
Magnetic resonance imaging (MRI) measurements of atrophy in an important area of the brain are an accurate predictor of multiple sclerosis (MS), according to a new study published online in the journal Radiology. According to the researchers, these atrophy measurements offer an improvement over current methods for evaluating patients at risk for MS.
MS develops as the body’s immune system attacks and damages myelin, the protective layer of fatty tissue that surrounds nerve cells within the brain and spinal cord. Symptoms include visual disturbances, muscle weakness and trouble with coordination and balance. People with severe cases can lose the ability to speak or walk.
Approximately 85 percent of people with MS suffer an initial, short-term neurological episode known as clinically isolated syndrome (CIS). A definitive MS diagnosis is based on a combination of factors, including medical history, neurological exams, development of a second clinical attack and detection of new and enlarging lesions with contrast-enhanced or T2-weighted MRI.
"For some time we’ve been trying to understand MRI biomarkers that predict MS development from the first onset of the disease," said Robert Zivadinov, M.D., Ph.D., FAAN, from the Buffalo Neuroimaging Analysis Center of the University at Buffalo in Buffalo, N.Y. "In the last couple of years, research has become much more focused on the thalamus."
The thalamus is a structure of gray matter deep within the brain that acts as a kind of relay center for nervous impulses. Recent studies found atrophy of the thalamus in all different MS disease types and detected thalamic volume loss in pediatric MS patients.
"Thalamic atrophy may become a hallmark of how we look at the disease and how we develop drugs to treat it," Dr. Zivadinov said.
For this study, Dr. Zivadinov and colleagues investigated the association between the development of thalamic atrophy and conversion to clinically definite MS.
"One of the most important reasons for the study was to understand which regions of the brain are most predictive of a second clinical attack," he said. "No one has really looked at this over the long term in a clinical trial."
The researchers used contrast-enhanced MRI for initial assessment of 216 CIS patients. They performed follow-up scans at six months, one year and two years. Over two years, 92 of 216 patients, or 42.6 percent, converted to clinically definite MS. Decreases in thalamic volume and increase in lateral ventricle volumes were the only MRI measures independently associated with the development of clinically definite MS.
"First, these results show that atrophy of the thalamus is associated with MS," Dr. Zivadinov said. "Second, they show that thalamic atrophy is a better predictor of clinically definite MS than accumulation of T2-weighted and contrast-enhanced lesions."
The findings suggest that measurement of thalamic atrophy and increase in ventricular size may help identify patients at high risk for conversion to clinically definite MS in future clinical trials involving CIS patients.
"Thalamic atrophy is an ideal MRI biomarker because it’s detectable at very early stage," Dr. Zivadinov said. "It has very good predictive value, and you will see it used more and more in the future."
The research team continues to follow the study group, with plans to publish results from the four-year follow-up next summer. They are also trying to learn more about the physiology of the thalamic involvement in MS.
"The next step is to look at where the lesions develop over two years with respect to the location of the atrophy," Dr. Zivadinov said. "Thalamic atrophy cannot be explained entirely by accumulation of lesions; there must be an independent component that leads to loss of thalamus."
MS affects more than 2 million people worldwide, according to the Multiple Sclerosis International Foundation. There is no cure, but early diagnosis and treatment can slow development of the disease.
(Source: eurekalert.org)
With their whiskers rats can detect the texture of objects in the same way as humans do using their fingertips. A study, in which some scientists of SISSA have taken part, shows that it is possible to understand what specific object has been touched by a rat by observing the activation of brain neurons. A further step towards understanding how the brain, also in humans, represents the outside world.
We know the world through the sensory representations within our brain. Such “reconstruction” is performed through the electrical activation of neural cells, the code that contains the information that is constantly processed by the brain. If we wish to understand what are the rules followed by the representation of the world inside the brain we have to comprehend how electrical activation is linked to the sensory experience. For this reason, a team of researchers including Mathew Diamond, Houman Safaai and Moritz von Heimendahl of the International School for Advanced Studies (SISSA) of Trieste have analyzed the behavior and the activation of neural networks in rats while they were carrying out tactile object recognition tests.
During the experiments researchers observed the performance of rats – the animals were discriminating one texture from another – along with the activation of a group of sensory neurons. “For the first time the study has monitored the activity of multiple neurons, while until now, due to technical limitations, researchers had examined only individual neurons,” explains Diamond, who heads up the Tactile Perception and Learning Lab at SISSA. “The activity of such groups of neurons is represented in our model as multi-dimensional clouds, comprising as many dimensions as the number of cells under examination (up to ten). We have observed a different cloud for the contact with each different texture.”
By analyzing the “clouds”, Diamond and his colleagues were able to successfully decode the object contacted by the rodent. “Our method is so accurate that when the rat would mistake one object for another, the decoding would also indicate a different object from the one actually touched. And this happened because the representation made by the brain – and, as a consequence, our decoding – appeared like that of a different object. Hence the error.”
Diamond’s team has no intention of stopping here. “In real life, we generally recognize objects using more senses all together, in an integrated manner. We use touch and sight at the same time, for instance,” explains Diamond. “For this reason we are now working on new experiments employing more neurons, with more complicated stimuli, and more senses, to build ‘multimodal’ representations of objects.”
More in detail…
This kind of “mind reading” carried out on rats’ brain by Diamond and his colleagues is important to understand how the brain forms a representation of the world. “Each one of us perceives a physical world outside ourselves, yet actually all we have at our disposal to create an experience of the world is the representation that our brain makes of it through the input of sensory organs” says Diamond.
To understand that such a representation is at the very least partial it is enough to think of all the information about the world that escapes us all the time: for instance, we are blind to infrared and ultraviolet rays, we are unable to hear certain sound frequencies or smell some chemical substances or others. Some details pertaining to the physical world are completely invisible or, to put it better, imperceptible (others are interpreted incorrectly, like visual illusions, for example.)
This is a further demonstration that what we perceive is not the physical world in itself, but the neuronal activation the world evokes inside our brain.