Do not disturb! How the brain filters out distractions

You know the feeling? You are trying to dial a phone number from memory… you have to concentrate…. then someone starts shouting out other numbers nearby. In a situation like that, your brain must ignore the distraction as best it can so as not to lose vital information from its working memory. A new paper published in Neuron by a team of neurobiologists led by Professor Andreas Nieder at the University of Tübingen gives insight into just how the brain manages this problem.

The researchers put rhesus monkey in a similar situation. The monkeys had to remember the number of dots in an image and reproduce the knowledge a moment later. While they were taking in the information, a distraction was introduced, showing a different number of dots. And even though the monkeys were mostly able to ignore the distraction, their concentration was disturbed and their memory performance suffered.

Measurements of the electrical activity of nerve cells in two key areas of the brain showed a surprising result: nerve cells in the prefrontal cortex signaled the distraction while it was being presented, but immediately restored the remembered information (the number of dots) once the distraction was switched off. In contrast, nerve cells in the parietal cortex were unimpressed by the distraction and reliably transmitted the information about the correct number of dots.

These findings provide important clues about the strategies and division of labor among different parts of the brain when it comes to using the working memory. “Different parts of the brain appear to use different strategies to filter out distractions,” says Dr. Simon Jacob, who carried out research in Tübingen before switching to the Psychiatric Clinic at the Charité hospitals in Berlin. “Nerve cells in the parietal cortex simply suppress the distraction, while nerve cells in the prefrontal cortex allow themselves to be momentarily distracted – only to return immediately to the truly important memory content.”

The researchers were surprised by the two brain areas’ difference in sensitivity to distraction. “We had assumed that the prefrontal cortex is able to filter out all kinds of distractions, while the parietal cortex was considered more vulnerable to disturbances,” says Professor Nieder. “We will have to rethink that. The memory-storage tasks and the strategies of each brain area are distributed differently from what we expected.”

Hippocampal activity during music listening exposes the memory-boosting power of music

For the first time the hippocampus—a brain structure crucial for creating long-lasting memories—has been observed to be active in response to recurring musical phrases while listening to music. Thus, the hippocampal involvement in long-term memory may be less specific than previously thought, indicating that short and long-term memory processes may depend on each other after all.

The study was conducted at the University of Jyväskylä and the AMI Center of Aalto University, by a group of researchers led by Academy Professor Petri Toiviainen, the Finnish Centre for Interdisciplinary Music Research (CIMR) at the University of Jyväskylä, and Dr. Elvira Brattico, Aalto University and the University of Helsinki. Results of the study were published in Cortex, a journal devoted to the study of the nervous system and behaviour.

“Our study basically shows an increase of activity in the medial temporal lobe areas—best known for being essential for long term memory—when musical motifs in the piece were repeated. This means that the lobe areas are engaged in the short-term recognition of musical phrases,” explains Iballa Burunat, the leading author of the study. Dr. Brattico adds: “Importantly, this hadn’t been observed before in music neuroscience.”

A fundamental highlight of the study is the use of a setting that is more natural than those traditionally employed in neuroscience: the participants’ only task was to attentively listen to an Argentinian tango from beginning to end. This kind of music provides well-defined, salient musical motifs that are easy to follow. They can be used to study recognition processes in the brain without having to resort to sound created in a lab. By using this more realistic approach, the researchers were able to identify brain areas involved in motif tracking without having to rely on the participants’ ability to self-report, which would have constrained the study of brain processes.

“We think that our novel method allowed us to uncover this phenomenon. In other words, the identified areas may also be related to the formation of a more permanent memory trace of a musical piece, enabled precisely by the very use of a real-life stimulus (the recording of a live performance) in a realistic situation where participants just listen to the music as their brain responses are recorded,” Iballa Burunat goes on to explain. Listening to the music from beginning to end may have imprinted the participants with a long lasting memory of the tune. This might not be expected were the participants exposed to a simpler stimulus in controlled conditions, as is the case in most studies in music and memory.

Although a real-life setting may be sufficient to trigger the involvement of the hippocampus, another explanation could lie in music’s capacity to elicit emotions. “We cannot ignore music’s emotional power which is thought to be crucial for the mnemonic power of music as to how and what we remember. There is evidence on the robust integration of music, memory and emotion—take for instance autobiographical memories. So it wouldn’t be surprising that the emotional content of the music may well have been a factor in triggering these limbic responses,” she continues. This makes sense, since the chosen musical piece by Astor Piazzolla was a tribute to his father after his sudden death, and so the main purpose of the piece was to be of a deeply emotional nature”. Certainly, the hippocampus—as part of the limbic system—is connected to neural circuitry involved in emotional behavior, and ongoing research suggests that emotional events seem to be more memorable than neutral ones. The authors emphasize that these results should motivate similar approaches to study verbal or visual short term memory by tracking the themes or repetitive structures of a given stimulus. Moreover, the study has implications for neurodegenerative diseases associated with hippocampal atrophy, like Alzheimer’s. “Music may positively affect patients if used wisely to stimulate their hippocampi, and thus their memory system,” Academy Professor Petri Toiviainen indicates. A better understanding of the link between music and memory could have widespread repercussions, leading to novel interventions to rehabilitate or improve the life quality of patients with neurodegenerative conditions.

Brain imaging shows enhanced executive brain function in people with musical training

A controlled study using functional MRI brain imaging reveals a possible biological link between early musical training and improved executive functioning in both children and adults, report researchers at Boston Children’s Hospital. The study, appearing online June 17 in the journal PLOS ONE, uses functional MRI of brain areas associated with executive function, adjusting for socioeconomic factors.

Executive functions are the high-level cognitive processes that enable people to quickly process and retain information, regulate their behaviors, make good choices, solve problems, plan and adjust to changing mental demands.

"Since executive functioning is a strong predictor of academic achievement, even more than IQ, we think our findings have strong educational implications," says study senior investigator Nadine Gaab, PhD, of the Laboratories of Cognitive Neuroscience at Boston Children’s. "While many schools are cutting music programs and spending more and more time on test preparation, our findings suggest that musical training may actually help to set up children for a better academic future."

While it’s already clear that musical training relates to cognitive abilities, few previous studies have looked at its effects on executive functions specifically. Among these studies, results have been mixed and limited by a lack of objective brain measurements, examination of only a few aspects of executive function, lack of well-defined musical training and control groups, and inadequate adjustment for factors like socioeconomic status.

Gaab and colleagues compared 15 musically trained children, 9 to 12, with a control group of 12 untrained children of the same age. Musically trained children had to have played an instrument for at least two years in regular private music lessons. (On average, the children had played for 5.2 years and practiced 3.7 hours per week, starting at the age of 5.9.) The researchers similarly compared 15 adults who were active professional musicians with 15 non-musicians. Both control groups had no musical training beyond general school requirements.

Since family demographic factors can influence whether a child gets private music lessons, the researchers matched the musician/non-musician groups for parental education, job status (parental or their own) and family income. The groups, also matched for IQ, underwent a battery of cognitive tests, and the children also had functional MRI imaging (fMRI) of their brains during testing.

On cognitive testing, adult musicians and musically trained children showed enhanced performance on several aspects of executive functioning. On fMRI, the children with musical training showed enhanced activation of specific areas of the prefrontal cortex during a test that made them switch between mental tasks. These areas, the supplementary motor area, the pre-supplementary area and the right ventrolateral prefrontal cortex, are known to be linked to executive function.

"Our results may also have implications for children and adults who are struggling with executive functioning, such as children with ADHD or [the] elderly," says Gaab. "Future studies have to determine whether music may be utilized as a therapeutic intervention tools for these children and adults."

The researchers note that children who study music may already have executive functioning abilities that somehow attract them to music and predispose them to stick with their lessons. To establish that musical training influences executive function, and not the other way around, they hope to perform additional studies that follow children over time, assigning them to musical training at random.

Crows’ memories are made of this

An important prerequisite for intelligence is a good short-term memory which can store and process the information needed for ongoing processes. This “working memory” is a kind of mental notepad – without it, we could not follow a conversation, do mental arithmetic, or play any simple game.

In the animal kingdom, the group of birds including crows and ravens – the corvids – are known for their intelligence because they have just such a working memory. However, their endbrain – which is highly-developed but has a fundamentally different structure from that of mammals – has no cerebral cortex; and that is the part of the brain which in mammals produces the working memory. How do corvids manage to store important information from moment to moment?

To answer that question, three researchers from the Institute for Neurobiology at Tübingen University taught crows to play a version of the children’s game of “pairs.” Using a computer monitor, Lena Veit, Konstantin Hartmann and Professor Andreas Nieder briefly showed the crows a random image. The crows had to remember it for one second before choosing the same image from a selection of four by tapping the remembered picture with their beaks. In order to choose the correct image, they must have stored it in a working memory – which they appeared to do quite easily.

Simultaneous measurements of electric potentials in the crows’ brains showed that nerve cells in one particular area of the endbrain were responsible for this capacity to remember. Although the image had disappeared from the screen, those cells remained active during the short period of remembering – retaining the information about the image until the crow retrieved it in order to make the right choice. If a crow couldn’t remember and selected a wrong image, those particular endbrain cells were barely activated. Prolonged activation of such cells ensured that important information could be stored and later accessed.

Professor Nieder and his team conclude that cognitive abilities are possible in a range of differently-structured brains. “Clearly, a good working memory – an important characteristic of human beings – can also exist without a layered cerebral cortex. The corvids’ fundamentally differently-structured endbrain shows that evolution has found a number of independent solutions,” says Lena Veit.

There are great benefits in the ability to temporarily store information. “An organism with a good working memory is intelligent; it is released from the compulsion to respond immediately to stimuli,” says Professor Nieder. “The big question is now – how do neural networks in the brain have to be composed in order to actively store and process information?”

Researchers use rhythmic brain activity to track memories in progress

University of Oregon researchers have tapped the rhythm of memories as they occur in near real time in the human brain.

Using electroencephalogram (EEG) electrodes attached to the scalps of 25 student subjects, a UO team led by psychology doctoral student David E. Anderson captured synchronized neural activity while they held a held a simple oriented bar located within a circle in short-term memory. The team, by monitoring these alpha rhythms, was able to decode the precise angle of the bar the subjects were locking onto and use that brain activity to predict which individuals could store memories with the highest quality or precision.

The findings are detailed in the May 28 issue of the Journal of Neuroscience. A color image illustrating how the item in memory was tracked by rhythmic brain activity in the alpha frequency band (8 to 12 beats per second) is on the journal’s cover page to showcase the research.

Although past research has decoded thoughts via brain activity, standard approaches are expensive and limited in their ability to track fast-moving mental representations, said Edward Awh, a professor in the UO’s Department of Psychology and Institute of Neuroscience. The new findings show that EEG measures of synchronized neural activity can precisely track the contents of memory at almost the speed of thought, he said.

"These findings provide strong evidence that these electrical oscillations in the alpha frequency band play a key role in a person’s ability to store a limited number of items in working memory," Awh said. “By identifying particular rhythms that are important to memory, we’re getting closer to understanding the low-level building blocks of this really limited cognitive ability. If this rhythm is what allows people to hold things in mind, then understanding how that rhythm is generated — and what restricts the number of things that can be represented — may provide insights into the basic capacity limits of the mind.”

The findings emerged from a basic research project led by Awh and co-author Edward K. Vogel — funded by the National Institutes of Health — that seeks to understand the limits of storing information. “It turns out that it’s quite restricted,” Awh said. “People can only think about a couple of things at a time, and they miss things that would seem to be extremely obvious and memorable if that limited set of resources is diverted elsewhere.”

Past work, mainly using functional magnetic resonance imaging (fMRI), has established that brain activity can track the content of memory. EEG, however, provides a much less expensive approach and can track mental activity with much a higher temporal resolution of about one-tenth of a second compared to about five seconds with fMRI.

"With EEG we get a fine-grained measure of the precise contents of memory, while benefitting from the superior temporal resolution of electrophysiological measures," Awh said. “This EEG approach is a powerful new tool for tracking and decoding mental representations with high temporal resolution. It should provide us with new insights into how rhythmic brain activity supports core memory processes.”

How brains remember and correct

Information processing in the brain is complex and involves both the processing of sensory inputs and the conversion of those inputs into behavior. The passing of electrical oscillations between networks of neurons in different parts of the brain is thought to be a critical component of cognition as well as conscious perception and awareness, but so far there has been little direct evidence linking specific neuronal oscillations to discrete thinking and behavior events. 

Jun Yamamoto and colleagues from the RIKEN–MIT Center for Neural Circuit Genetics have now detected a brief burst of nerve activity oscillating in two specific parts of the mouse brain just before a correct choice is made, either when planning an action or when correcting a mistake. 

The researchers searched for evidence of specific neuronal oscillations by studying mice navigating a T-shaped maze with a reward at the end of one arm of the T. Just before trained mice made the correct choice of direction, Yamamoto and his colleagues observed a brief burst of synchronized high-frequency gamma waves oscillating in specific parts of the entorhinal cortex and hippocampus. 

Yamamoto was fascinated to notice that the burst of gamma waves also occurred just before mice that had originally turned in the wrong direction realized their mistake and turned round. He called this the “oops” moment, and the results indicate that similar neuronal activity occurs when making a correct choice either immediately or on realization of an error. No such gamma-wave activity was detected when mice made the wrong choice without correcting it.

To further test the link between the gamma synchrony and the memory recall process, the researchers genetically engineered mice with light-activated ion channels that could block the gamma waves. When these channels were activated, the gamma waves ceased and the mice could no longer accurately choose the right direction or correct their wrong choices.

“Our work is telling us about how the brain recalls remembered information at critical moments,” says Yamamoto. “It suggests that synchronized gamma oscillations actually contribute to the animal’s correct choice rather than being a consequence of their choice.” The finding sheds light on the fundamental mechanism underlying the successful retrieval of working memory. Yamamoto now intends to see if these initial findings apply to other brain regions. 

The results also provide new insight into the phenomenon of animal consciousness. “Our findings provide evidence that animals employ a behavior monitoring process called metacognition that typically requires conscious awareness,” says Yamamoto.

Oops! Researchers find neural signature for mistake correction

Culminating an 8 year search, scientists at the RIKEN-MIT Center for Neural Circuit Genetics captured an elusive brain signal underlying memory transfer and, in doing so, pinpointed the first neural circuit for “oops”—the precise moment when one becomes consciously aware of a self-made mistake and takes corrective action.

Cognitive scientists use ‘I spy’ to show spoken language helps direct children’s eyes

In a new study, Indiana University cognitive scientists Catarina Vales and Linda Smith demonstrate that children spot objects more quickly when prompted by words than if they are only prompted by images.

Language, the study suggests, is transformative: More so than images, spoken language taps into children’s cognitive system, enhancing their ability to learn and to navigate cluttered environments. As such the study, published last week in the journal Developmental Science, opens up new avenues for research into the way language might shape the course of developmental disabilities such as ADHD, difficulties with school, and other attention-related problems.

In the experiment, children played a series of “I spy” games, widely used to study attention and memory in adults. Asked to look for one image in a crowded scene on a computer screen, the children were shown a picture of the object they needed to find — a bed, for example, hidden in a group of couches.

"If the name of the target object was also said, the children were much faster at finding it and less distracted by the other objects in the scene," said Vales, a graduate student in the Department of Psychological and Brain Sciences.

"What we’ve shown is that in 3-year-old children, words activate memories that then rapidly deploy attention and lead children to find the relevant object in a cluttered array," said Smith, Chancellor’s Professor in the Department of Psychological and Brain Sciences. "Words call up an idea that is more robust than an image and to which we more rapidly respond. Words have a way of calling up what you know that filters the environment for you.”

The study, she said , “is the first clear demonstration of the impact of words on the way children navigate the visual world and is a first step toward understanding the way language influences visual attention, raising new testable hypotheses about the process.”

Vales said the use of language can change how people inspect the world around them.

"We also know that language will change the way people perform in a lot of different laboratory tasks," she said. "And if you have a child with ADHD who has a hard time focusing, one of the things parents are told to do is to use words to walk the child through what she needs to do. So there is this notion that words change cognition. The question is ‘how?’"

Vales said their research results “begin to tell us precisely how words help, the kinds of cognitive processes words tap into to change how children behave. For instance, the difference between search times, with and without naming the target object, indicate a key role for a kind of brief visual memory known as working memory, that helps us remember what we just saw as we look to something new. Words put ideas in working memory faster than images.”

For this reason, language may play an important role in a number of developmental disabilities.

"Limitations in working memory have been implicated in almost every developmental disability, especially those concerned with language, reading and negative outcomes in school," Smith said. "These results also suggest the culprit for these difficulties may be language in addition to working memory.

"This study changes the causal arrow a little bit. People have thought that children have difficulty with language because they don’t have enough working memory to learn language. This turns it around because it suggests that language may also make working memory more effective."

How does this matter to child development?

"Children learn in the real world, and the real world is a cluttered place," Smith said. "If you don’t know where to look, chances are you don’t learn anything. The words you know are a driving force behind attention. People have not thought about it as important or pervasive, but once children acquire language, it changes everything about their cognitive system."

"Our results suggest that language has huge effects, not just on talking, but on attention — which can determine how children learn, how much they learn and how well they learn," Vales said.