1. Study suggests brain is still ‘connected’ during non-REM sleep

    December 9, 2017 by Ashley

    From the SINC press release:

    When we sleep, our organism goes through different phases of sleep, however the brain remains interconnected during non-REM sleep, which was thought not to happen. The finding by a European team of researchers has also made it possible to analyse the scientific basis of consciousness, an increasingly important field of neuroscience.

    Sleep is composed of various cycles in which there are different stages: slow and fast-wave, which make up non-REM sleep and REM sleep. During the night, it is normal to experience four or five complete cycles, each lasting around ninety minutes.

    Various investigations have shown that communication between different areas of the cerebral cortex is interrupted during non-REM sleep and also when a patient is under anaesthesia, due to the loss of consciousness.

    “It was thought that the brain disconnected during non-REM sleep and that the individual areas could no longer communicate effectively,” explained Umberto Olcese, a researcher from the Swammerdam Institute for Life Sciences of the University of Amsterdam (Netherlands).

    Olcese and the rest of the research team (which involved researchers from the European CANON project and that was led by Prof. Cyriel Pennartz, who participates in the European Flagship Human Brain Project) have discovered that not all forms of communication within the cerebral cortex are lost during non-REM sleep. Specifically, correlations are preserved between neurons located within individual regions and between some subpopulations of neurons located in different cerebral areas.

    To reach these conclusions, published in ‘The Journal of Neuroscience‘, the researchers studied how the brain regulates the neuronal connections of the neocortex and hippocampus in rats.

    Advances in the study of consciousness

    In a second investigation published in the same journal, a team of investigators from the Human Brain Project and the CANON project analysed the state of consciousness from a neuroscience perspective.

    Although historically this concept has been studied from a philosophical standpoint, experts have reviewed various scientific studies which reflect the importance of a proper communication between cortical areas in the process.

    “Neuroscientific research on consciousness driven by new methods and theoretical advances should be increasingly robust and accepted, since notable scientific and clinical progress is now starting to be made,” the authors pointed out.


  2. Tracking down genetic influences on brain disorders

    December 8, 2017 by Ashley

    From the Universität Basel press release:

    New findings will help to identify the genetic causes of brain disorders: researchers at the Universities of Basel, Bonn and Cologne have presented a systematic catalog of specific variable locations in the genome that influence gene activity in the human hippocampus, as they report in the journal Nature Communications.

    Individual differences in gene regulation contribute to the development of numerous multifactorial disorders. Researchers are therefore attempting to clarify the influence of genetic variants (single-nucleotide polymorphisms, or SNPs) on gene expression and on the epigenetic modification of regulatory sections of the genome (DNA methylation). The German-Swiss team has now studied the genetic determinants of gene expression, as well as the process of DNA methylation in the human hippocampus.

    Three million genomic locations analyzed

    The researchers have presented an extensive catalog of variable locations in the genome — that is, of SNPs — that affect the activity of genes in the human hippocampus. Specifically, they have analyzed the influence of more than three million SNPs, spread throughout the genome, on activity in nearby genes and the methylation of adjacent DNA sections.

    The special thing about their work is that the researchers used freshly frozen hippocampus tissue obtained during surgery on 110 treatment-resistant epilepsy patients. They extracted DNA and RNA from the hippocampus tissue and, for all of the obtained samples, used microchips to determine several hundred thousand SNPs, as well as the degree of methylation at several hundred thousand locations (known as CpG dinucleotides) in the genome. Among other analyses, they measured the gene expression of over 15,000 genes using RNA microchips.

    Development of schizophrenia

    The researchers also demonstrated the preferred areas in which variably methylated CpG dinucleotides appear in the genome, and they were able to assign these to specific regulatory elements, revealing a link to brain disorders: a significant proportion of the identified SNPs that individually influence DNA methylation and gene expression in the hippocampus also contribute to the development of schizophrenia. This underlines the potentially significant role played by SNPs with a regulatory effect in the development of brain disorders.

    The study’s findings will make it considerably easier to interpret evidence of genetic associations with brain disorders in the future. Of the SNPs involved in the development of brain disorders, many of those identified in recent years are located in the non-coding part of the genome. Their functional effect in cells is therefore largely unclear.

    An important factor in the project’s success was the close cooperation between the Universities of Basel, Bonn and Cologne. This collaboration is supported by the IntegraMent Consortium, which is sponsored by Germany’s Federal Ministry of Education and Research and coordinated by Professor Markus Nöthen of the University of Bonn.


  3. Neuroimaging of soccer fans’ brain reveals neural basis of ingroup altruistic motivation

    by Ashley

    From the D’Or Institute for Research and Education press release:

    Why sports fans can be so crazy about their teams? The answer lies deeply rooted in their brains, says a new study. Group belongingness is considered a basic human need and has been stated as a critical feature for hominin evolution. In the past decades, studies have shown our tendency to benefit ingroup over outgroup members during decisions, which can be explained by the reciprocal identification among members.

    The study, published in Nature’s Scientific Reports journal on November 23th, reveals for the first time the brain functioning involved in altruistic motivation among soccer fans — a “natural group” that shows strong bonds in real-life settings. The functional MRI study sheds light into the neural basis of prosocial behaviour of ingroup attachment.

    “Attachment to cultural groups is a unique property of humans, fundamental for our survival, which, in turn, makes the investigation of its neural basis very critical,” states Dr. Jorge Moll, neuroscientist and senior author of the study. He is the head of the D’Or Institute for Research and Education (IDOR), where the research was conducted.

    To do so, researchers recruited 27 soccer fans of Brazilian teams for the experiment. Inside the functional Magnetic Resonance (fMR) scanner, supporters of the four most popular soccer clubs in Rio de Janeiro had to decide whether they want to donate a specific amount of money to (ii) anonymous fans of their own soccer teams, (ii) anonymous non-fans or (iii) to keep the amount to themselves. During these donation tasks, the fMR machine captured in detail their brain functioning in order to elucidate the neural underpinnings of ingroup motivation and altruistic decisions.

    According to Dr. Tiago Bortolini, lead author of the study, from IDOR and the Federal University of Rio de Janeiro, “soccer fans constitutes an example of natural groups, which are reflected in daily life situations and thus provide an unique opportunity to investigate group belongingness in a more ecologic fashion.”

    The goal of the study was to investigate the neural mechanisms responsible for altruistic motivation among members of the same social group. In other words, what are the soccer fans’ brain areas involved in this kind of behaviour?

    Differently than most of the studies in the scientific literature, researchers designed a highly effortful task to probe participats engagement in obtaining money for themselves or to be donated to other participants. This was done by having participants squeezing a pressure device that they held in their hands during the experimental trials.

    “This allowed us to measure their real motivation during the donation tasks, since greater amounts of money required lot of pressure effort on the handgrip device,” explains Dr. Bortolini.

    Results of the donation trials (measured by how strong they squeezed the handgrip device) showed that, on average, they invested more effort to benefit anonymous fans of their own soccer clubs than non-fans. Greater effort was observed to obtain money for themselves, however (yes, they did take better care of themselves!).

    In order to elucidate what happens in the soccer fans’ brain during the donation tasks, researchers analyzed brain activation in common for all three types of donation: to soccer fans, to non-fans or to themselves. Analyses showed that the medial orbitofrontal cortex (mOFC) a brain area extremely important for subjective value of choice alternatives, showed increased activity in all conditions.

    Since this brain area plays a critical role in decision and values, researchers decided to investigate how this area (mOFC) interacts with other parts of the brain. This analysis revealed a close relationship (which means more “connectivity”) of mOFC with the subgenual cingulate cortex — a region that has previously been implicated in altruistic decisions to charitable organizations and in family belongingness — only when donations were targeted to fans of the same soccer club. A straightforward interpretation is that fans respond to their team mates, even unknown ones, in a similar way that they respond to loved family members or when making noble altruistic choices.

    “Understanding the neural mechanisms involved in group belongingness and pro-group behaviour can pave the way for developing novel brain modulation techniques able to address clinical problems, such as antisocial behaviors and other psychiatric symptoms, including sports-related agressive attitudes and behaviors,” said Dr. Bortoloni.


  4. Study suggests ‘mind’s eye blink’ proves ‘paying attention’ is not just a figure of speech

    by Ashley

    From the Vanderbilt University press release:

    When your attention shifts from one place to another, your brain blinks. The blinks are momentary unconscious gaps in visual perception and came as a surprise to the team of Vanderbilt psychologists who discovered the phenomenon while studying the benefits of attention.

    “Attention is beneficial because it increases our ability to detect visual signals even when we are looking in a different direction,” said Assistant Professor of Psychology Alex Maier, who directed the study. “The ‘mind’s eye blinks’ that occur every time your attention shifts are the sensory processing costs that we pay for this capability.”

    Details of their study are described in a paper titled “Spiking suppression precedes cued attentional enhancement of neural responses in primary visual cortex” published online Nov. 23 by the journal Cerebral Cortex.

    “There have been several behavior studies in the past that have suggested there is a cost to paying attention. But our study is the first to demonstrate a sensory brain mechanism underlying this phenomenon,” said first author Michele Cox, who is a psychology doctoral student at Vanderbilt.

    The research was conducted with macaque monkeys that were trained to shift their attention among different objects on a display screen while the researchers monitored the pattern of neuron activity taking place in their brains. Primates are particularly suited for the study because they can shift their attention without moving their eyes. Most animals do not have this ability.

    “We trained macaques to play a video game that rewarded them with apple juice when they paid attention to certain visual objects. Once they became expert at the game, we measured the activity in their visual cortex when they played,” said Maier.

    By combining advanced recording techniques that simultaneously track large numbers of neurons with sophisticated computational analyses, the researchers discovered that the activity of the neurons in the visual cortex were momentarily disrupted when the game required the animals to shift their attention. They also traced the source of the disruptions to parts of the brain involved in guiding attention, not back to the eyes.

    Mind’s eye blink is closely related to “attentional blink” that has been studied by Cornelius Vanderbilt Professor of Psychology David Zald and Professor of Psychology René Marois. Attentional blink is a phenomenon that occurs when a person is presented with a rapid series of images. If the spacing between two images is too short, the observer doesn’t detect the second image. In 2005, Zald determined that the time of temporary blindness following violent or erotic images was significantly longer than it is for emotionally neutral images.


  5. Brain researchers gain greater understanding of how we generate internal experiences

    December 7, 2017 by Ashley

    From the Bar-Ilan University press release:

    Our mental life is rich with an enormous number of internal experiences. The diversity of these experiences is astonishing. We can vividly recall an episode from childhood as well as what we did just five minutes ago. We can imagine and plan in detail our next vacation. We can be moved to tears by the story of an absolute stranger or even of a fictitious character. How does the brain achieve this magic?

    A new study published in the journal Nature Human Behavior may bring us closer to understanding this challenging phenomenon. The study was carried out by Dr. Vadim Axelrod and Prof. Moshe Bar, from the Gonda (Goldschmied) Multidisciplinary Brain Research Center at Bar-Ilan University, and Prof. Geraint Rees, from the Institute of Cognitive Neuroscience at University College London.

    “We have a subjective impression that each of our internal experiences is a unitary, indivisible entity. Yet the brain, according to prevalent view in the scientific community, realizes each of our experiences through a combination of different components,” explains Dr. Axelrod, the principal investigator at the Gonda (Goldschmied) Multidisciplinary Brain Research Center and the lead author of the paper. “When we recall a recent birthday party, for example, the brain likely activates a number of different systems, such as a system that is responsible for retrieving memory of events, a system that is responsible for building a vivid scene in our mind, and a system that is responsible for moving back in time. In our study we aimed to test this hypothesis.”

    The researchers scanned forty-one healthy volunteers using functional MRI. The participants took part in four different experiments. The authors used three of the experiments to identify three brain systems. The main result was that these three systems were active at the same time during the fourth experiment. In other words, the researchers showed that internal experiences, such as recalling personal memories, are associated with the simultaneous activity of different cognitive systems.

    It might sound like science fiction that it was possible to see separate components of internal thoughts of the participants as they were lying in the MRI with their eyes closed and recalling their personal lives. “Obviously, our internal experience is mediated by much more than three cognitive systems. We hope that the approach we used will help in the future to identify additional systems,” summarize the scientists.


  6. Scientists identify the segmentation and consolidation mechanism of long-term memories

    by Ashley

    From the IDIBELL-Bellvitge Biomedical Research Institute press release:

    A study led by the Bellvitge Biomedical Research Institute (IDIBELL) has identified a neural mechanism in humans that allows us to segment our experience in discrete memory units. According to the research, published in the scientific journal Current Biology, the brain identifies context changes as “frontiers” in the flow of our experience and uses them to fragment the course of events into small units of memory that can be stored long-term. The study shows that this process takes place during the identification of a boundary event thanks to the rapid reactivation of the flow of information that precedes it.

    The research was carried out by Ignacio Sols, as the first author, and Lluís Fuentemilla, all of them researchers from the Cognition and Brain Plasticity Group of IDIBELL and the Neurosciences Institute of the University of Barcelona (UB). Sara DuBrow and Lila Davachi, from the department of psychology at the University of New York, in the United States, also collaborated.

    Continuous experiences, discrete memories

    Despite our day-to-day experiences are lived seamlessly, without any cut, scientific research has shown that changes in the context can influence the representation we make of these experiences in our memory, where they become discrete memories. “What we were interested in finding out in this case was whether this process of compartmentalization of memories begins at the same moment in which the experience is lived, and what neural mechanism could be involved. “It is known from previous studies in animals that the active neural pattern during a certain experience is reactivated once this experience ends, so the idea was to observe in a group of volunteers what happened at the brain level when a certain episode ended,” explains researcher Ignacio Soles.

    The segmentation theory of events, on which the published study is based, argues that the brain acts on the grounds of constant predictions based on previous experience; When these predictions fail, for example because there is an unexpected change of context, the brain interprets this moment as a boundary event, which delimits the neural coding of the lived experiences.

    “Boundary events” trigger memory encoding

    To deepen this segmentation and reactivation mechanism of memories, the researchers designed an experiment in order to recreate in a simplified way these “boundary events”; the participants had to observe a sequence of images of the same category — for example, human faces — that was interrupted by an element of a different category — for example, an object.

    The response of the participants was measured behaviorally using memory tests in which they were asked, given two previously visualized elements, which one they had seen first. The results of the study conclude that the elements contained in a single episode — two faces observed within a continuous sequence of faces, for example — were significantly easier to temporarily put in order than those that had been observed in different episodes — two faces shown in a sequence in which there were the images of two objects in the middle.

    “Episodes built from the sequential experience allow us to generate prediction models of what may happen afterwards. The context or boundary event changes would be perceived as errors in our prediction and would serve our memory system to mark the end of an episode and the possible start of a new one, and through this process, the memory system can implement, during the course of our experience, an organizational model that would impact on how the memories of our experience will be stored,” explains UB professor Lluís Fuentemilla, last author of the study.

    During the experiment, the neural activity of the participants was monitored by encephalogram (EEG), a non-invasive technique that can be used to register activity in the range of milliseconds. According to Ignacio Sols, first author of the study, the analysis of the electroencephalography records confirms that “the neural patterns of the original coding of the episodic sequence are reactivated exclusively during the appearance of the corresponding boundary event, and not while the episode is unfolding. This proves that this process does not begin during an episode, but when the brain interprets that this episode has ended.”

    Rapid reactivation of memories leads to long-term memory consolidation.

    This research team also suggests that the segmentation of the lived episodes in packages or pieces defined by “frontier events” is a first step towards the storage of these memories in long-term memory. “The reactivation of memory is a mechanism already known in relation to the consolidation of memories, but until now it has been mainly studied as a neural mechanism that takes place during sleep, and not during the course of the experience, as we have done here,” explains Fuentemilla.


  7. Study suggests marriage may help stave off dementia

    by Ashley

    From the BMJ press release:

    Marriage may lower the risk of developing dementia, concludes a synthesis of the available evidence published online in the Journal of Neurology Neurosurgery & Psychiatry.

    Lifelong singletons and widowers are at heightened risk of developing the disease, the findings indicate, although single status may no longer be quite the health hazard it once seemed to be, the researchers acknowledge.

    They base their findings on data from 15 relevant studies published up to the end of 2016. These looked at the potential role of marital status on dementia risk, and involved more than 800,000 participants from Europe, North and South America, and Asia.

    Married people accounted for between 28 and 80 per cent of people in the included studies; the widowed made up between around 8 and 48 per cent; the divorced between 0 and 16 per cent; and lifelong singletons between 0 and 32.5 per cent.

    Pooled analysis of the data showed that compared with those who were married, lifelong singletons were 42 per cent more likely to develop dementia, after taking account of age and sex.

    Part of this risk might be explained by poorer physical health among lifelong single people, suggest the researchers.

    However, the most recent studies, which included people born after 1927, indicated a risk of 24 per cent, which suggests that this may have lessened over time, although it is not clear why, say the researchers.

    The widowed were 20 per cent more likely to develop dementia than married people, although the strength of this association was somewhat weakened when educational attainment was factored in.

    But bereavement is likely to boost stress levels, which have been associated with impaired nerve signalling and cognitive abilities, the researchers note.

    No such associations were found for those who had divorced their partners, although this may partly be down to the smaller numbers of people of this status included in the studies, the researchers point out.

    But the lower risk among married people persisted even after further more detailed analysis, which, the researchers suggest, reflects “the robustness of the findings.”

    These findings are based on observational studies so no firm conclusions about cause and effect can be drawn, and the researchers point to several caveats, including the design of some of the included studies, and the lack of information on the duration of widowhood or divorce.

    Nevertheless, they proffer several explanations for the associations they found. Marriage may help both partners to have healthier lifestyles, including exercising more, eating a healthy diet, and smoking and drinking less, all of which have been associated with lower risk of dementia.

    Couples may also have more opportunities for social engagement than single people — a factor that has been linked to better health and lower dementia risk, they suggest.

    In a linked editorial, Christopher Chen and Vincent Mok, of, respectively, the National University of Singapore and the Chinese University of Hong Kong, suggest that should marital status be added to the list of modifiable risk factors for dementia, “the challenge remains as to how these observations can be translated into effective means of dementia prevention.”

    The discovery of potentially modifiable risk factors doesn’t mean that dementia can easily be prevented, they emphasise.

    “Therefore, ways of destigmatising dementia and producing dementia-friendly communities more accepting and embracing of the kinds of disruptions that dementia can produce should progress alongside biomedical and public health programmes,” they conclude.


  8. Study suggests smartphone addiction creates imbalance in brain

    December 6, 2017 by Ashley

    From the Radiological Society of North America press release:

    Researchers have found an imbalance in the brain chemistry of young people addicted to smartphones and the internet, according to a study presented today at the annual meeting of the Radiological Society of North America (RSNA).

    According to a recent Pew Research Center study, 46 percent of Americans say they could not live without their smartphones. While this sentiment is clearly hyperbole, more and more people are becoming increasingly dependent on smartphones and other portable electronic devices for news, information, games, and even the occasional phone call.

    Along with a growing concern that young people, in particular, may be spending too much time staring into their phones instead of interacting with others, come questions as to the immediate effects on the brain and the possible long-term consequences of such habits.

    Hyung Suk Seo, M.D., professor of neuroradiology at Korea University in Seoul, South Korea, and colleagues used magnetic resonance spectroscopy (MRS) to gain unique insight into the brains of smartphone- and internet-addicted teenagers. MRS is a type of MRI that measures the brain’s chemical composition.

    The study involved 19 young people (mean age 15.5, 9 males) diagnosed with internet or smartphone addiction and 19 gender- and age-matched healthy controls. Twelve of the addicted youth received nine weeks of cognitive behavioral therapy, modified from a cognitive therapy program for gaming addiction, as part of the study.

    Researchers used standardized internet and smartphone addiction tests to measure the severity of internet addiction. Questions focused on the extent to which internet and smartphone use affects daily routines, social life, productivity, sleeping patterns and feelings.

    “The higher the score, the more severe the addiction,” Dr. Seo said.

    Dr. Seo reported that the addicted teenagers had significantly higher scores in depression, anxiety, insomnia severity and impulsivity.

    The researchers performed MRS exams on the addicted youth prior to and following behavioral therapy and a single MRS study on the control patients to measure levels of gamma aminobutyric acid, or GABA, a neurotransmitter in the brain that inhibits or slows down brain signals, and glutamate-glutamine (Glx), a neurotransmitter that causes neurons to become more electrically excited. Previous studies have found GABA to be involved in vision and motor control and the regulation of various brain functions, including anxiety.

    The results of the MRS revealed that, compared to the healthy controls, the ratio of GABA to Glx was significantly increased in the anterior cingulate cortex of smartphone- and internet-addicted youth prior to therapy.

    Dr. Seo said the ratios of GABA to creatine and GABA to glutamate were significantly correlated to clinical scales of internet and smartphone addictions, depression and anxiety.

    Having too much GABA can result in a number of side effects, including drowsiness and anxiety.

    More study is needed to understand the clinical implications of the findings, but Dr. Seo believes that increased GABA in the anterior cingulate gyrus in internet and smartphone addiction may be related to the functional loss of integration and regulation of processing in the cognitive and emotional neural network.

    The good news is GABA to Glx ratios in the addicted youth significantly decreased or normalized after cognitive behavioral therapy.

    “The increased GABA levels and disrupted balance between GABA and glutamate in the anterior cingulate cortex may contribute to our understanding the pathophysiology of and treatment for addictions,” Dr. Seo said.


  9. Study suggests eye contact with your baby helps synchronize your brainwaves

    by Ashley

    From the University of Cambridge press release:

    When a parent and infant interact, various aspects of their behaviour can synchronise, including their gaze, emotions and heartrate, but little is known about whether their brain activity also synchronises — and what the consequences of this might be.

    Brainwaves reflect the group-level activity of millions of neurons and are involved in information transfer between brain regions. Previous studies have shown that when two adults are talking to each other, communication is more successful if their brainwaves are in synchrony.

    Researchers at the Baby-LINC Lab at the University of Cambridge carried out a study to explore whether infants can synchronise their brainwaves to adults too — and whether eye contact might influence this. Their results are published in the Proceedings of National Academy of Sciences (PNAS).

    The team examined the brainwave patterns of 36 infants (17 in the first experiment and 19 in the second) using electroencephalography (EEG), which measures patterns of brain electrical activity via electrodes in a skull cap worn by the participants. They compared the infants’ brain activity to that of the adult who was singing nursery rhymes to the infant.

    In the first of two experiments, the infant watched a video of an adult as she sang nursery rhymes. First, the adult — whose brainwave patterns had already been recorded — was looking directly at the infant. Then, she turned her head to avert her gaze, while still singing nursery rhymes. Finally, she turned her head away, but her eyes looked directly back at the infant.

    As anticipated, the researchers found that infants’ brainwaves were more synchronised to the adults’ when the adult’s gaze met the infant’s, as compared to when her gaze was averted. Interestingly, the greatest synchronising effect occurred when the adults’ head was turned away but her eyes still looked directly at the infant. The researchers say this may be because such a gaze appears highly deliberate, and so provides a stronger signal to the infant that the adult intends to communicate with her.

    In the second experiment, a real adult replaced the video. She only looked either directly at the infant or averted her gaze while singing nursery rhymes. This time, however, her brainwaves could be monitored live to see whether her brainwave patterns were being influenced by the infant’s as well as the other way round.

    This time, both infants and adults became more synchronised to each other’s brain activity when mutual eye contact was established. This occurred even though the adult could see the infant at all times, and infants were equally interested in looking at the adult even when she looked away. The researchers say that this shows that brainwave synchronisation isn’t just due to seeing a face or finding something interesting, but about sharing an intention to communicate.

    To measure infants’ intention to communicate, the researcher measured how many ‘vocalisations’ infants made to the experimenter. As predicted, infants made a greater effort to communicate, making more ‘vocalisations’, when the adult made direct eye contact — and individual infants who made longer vocalisations also had higher brainwave synchrony with the adult.

    Dr Victoria Leong, lead author on the study said: “When the adult and infant are looking at each other, they are signalling their availability and intention to communicate with each other. We found that both adult and infant brains respond to a gaze signal by becoming more in sync with their partner. This mechanism could prepare parents and babies to communicate, by synchronising when to speak and when to listen, which would also make learning more effective.”

    Dr Sam Wass, last author on the study, said: “We don’t know what it is, yet, that causes this synchronous brain activity. We’re certainly not claiming to have discovered telepathy! In this study, we were looking at whether infants can synchronise their brains to someone else, just as adults can. And we were also trying to figure out what gives rise to the synchrony.

    “Our findings suggested eye gaze and vocalisations may both, somehow, play a role. But the brain synchrony we were observing was at such high time-scales — of three to nine oscillations per second — that we still need to figure out how exactly eye gaze and vocalisations create it.”


  10. Talking to ourselves and voices in our heads

    by Ashley

    From the University of New South Wales press release:

    As far our brain is concerned, talking to ourselves in our heads may be fundamentally the same as speaking our thoughts out loud, new research shows. The findings may have important implications for understanding why people with mental illnesses such as schizophrenia hear voices.

    UNSW Sydney scientist and study first author Associate Professor Thomas Whitford says it has long been thought that these auditory-verbal hallucinations arise from abnormalities in inner speech — our silent internal dialogue.

    “This study provides the tools for investigating this once untestable assumption,” says Associate Professor Whitford, of the UNSW School of Psychology.

    Previous research suggests that when we prepare to speak out loud, our brain creates a copy of the instructions that are sent to our lips, mouth and vocal cords. This copy is known as an efference-copy.

    It is sent to the region of the brain that processes sound to predict what sound it is about to hear. This allows the brain to discriminate between the predictable sounds that we have produced ourselves, and the less predictable sounds that are produced by other people.

    “The efference-copy dampens the brain’s response to self-generated vocalisations, giving less mental resources to these sounds, because they are so predictable,” says Associate Professor Whitford.

    “This is why we can’t tickle ourselves. When I rub the sole of my foot, my brain predicts the sensation I will feel and doesn’t respond strongly to it. But if someone else rubs my sole unexpectedly, the exact same sensation will be unpredicted. The brain’s response will be much larger and creates a ticklish feeling.”

    The study, published in the journal eLife, set out to determine whether inner speech — an internal mental process — elicits a similar efference-copy as the one associated with the production of spoken words.

    The research team developed an objective method for measuring the purely mental action of inner speech. Specifically, their study in 42 healthy participants assessed the degree to which imagined sounds interfered with the brain activity elicited by actual sounds, using electroencephalography (EEG).

    The researchers found that, just as for vocalized speech, simply imagining making a sound reduced the brain activity that occurred when people simultaneously heard that sound. People’s thoughts were enough to change the way their brain perceived sounds. In effect, when people imagined sounds, those sounds seemed quieter.

    “By providing a way to directly and precisely measure the effect of inner speech on the brain, this research opens the door to understanding how inner speech might be different in people with psychotic illnesses such as schizophrenia,” says Associate Professor Whitford.

    “We all hear voices in our heads. Perhaps the problem arises when our brain is unable to tell that we are the ones producing them.