Disturbances in Working Memory in Children
There is news from England about some research that indicates that many children who were thought to have low intelligence actually have a problem with working memory, the ability to hold information in your head and manipulate it mentally. It is largely genetic and if it fails to function normally it can affect long-term academic success into adulthood and prevent children from achieving their potential.
The researchers from Durham University surveyed over three thousand children in 35 schools across the UK using the first tool to enabled them to assess memory capacity in the classroom. They found that ten per cent of school children across all age ranges suffer from poor working memory seriously affecting their learning. Poor working memory is rarely identified by teachers, who often describe children with this problem as inattentive or as having lower levels of intelligence.
The new tool is a combination of a checklist and computer program created after many years of research into poor working memory in children, and it should
enable psychologists and teachers to identify and assess children’s
memory capacity as early as four years old.
The hope is that early assessment of children will enable teachers to adopt new approaches to teaching.
The checklist, called the Working Memory Rating Scale (WMRS), will enable teachers to identify children who they think may have a problem with working memory without immediately subjecting them to a test. A high score on this checklist shows that a child is likely to have working memory problems that will affect his or her academic progress.
Children can be evaluated using the computerized Automated Working Memory Assessment (AWMA). The tools also suggest ways for teachers to manage the children’s working memory loads that will minimize the chances of children failing to complete tasks. Recommendations include repetition of instructions, talking in simple short sentences and breaking down tasks into smaller chunks of information.
Pearson Assessment publishes the tools.
This is interesting work, but we still need more research to answer another question: disturbances in working memory have been identified in attention deficit/hyperactivity disorder (ADHD). So the question is whether many of the children found to have defects in working memory may actually have had ADHD.
Memory and Emotion
Your humble reporter has had more than his fair share of major life events. As a sixteen year old I was a passenger in car that had a meeting with another vehicle driving down the wrong side of the road. This was in England, where folk always do drive on the “wrong” side, but the fellow who was kind enough to arrange the collision could never explain why he was driving on the “American” side.
The interesting thing is that the memory of the crash is seared into my memory: I can remember the license plate of the vehicle that hit us. Some people call that a “flashbulb memory.”
If you live in the United States you probably have clear and fairly accurate memories of where you were and what you were doing on September 11th 2001.
This kind of experience is not uncommon: most of us have noticed that events that occur during heightened states of emotional arousal, such as fear, anger, happiness and sex are far more memorable than less dramatic occurrences. The emotional “load” of an event is a key factor in remembering it. Previous studies have confirmed that heightened states of emotion can facilitate learning and memory.
This makes good evolutionary sense: emotionally charged events are likely to be the ones that we need to remember. From an evolutionary perspective, it is more important to remember where Mr. Saber-tooth Tiger lives, rather than the names of the Kings and Queens of England.
Therefore the regions of the brain that are responsible for the storage of memories need to distinguish between important experiences and those that less significant for survival. The brain must have some mechanisms for giving priority to emotionally charged memories, so that they are converted and stored in long-term memory.
The downside is that in some situations, for instance posttraumatic stress disorder (PTSD), this process can become pathological and people can be tormented by persistent vivid memories of traumatic events.
Writing in the journal Cell, researchers from Johns Hopkins University and their collaborators at Cold Spring Harbor Laboratory and New York University may have identified the biological basis for this phenomenon. Memories in the brain are held in neurological circuits and each new experience creates a new circuit. The investigators have found that the hormone norepinephrine, which is released during emotional arousal, serves to “prime” nerve cells to remember events. They do this by increasing the neurons’ chemical sensitivity at the precise sites where nerves rewire to form new memory circuits.
Norepinephrine is often described as one of the “fight or flight” hormones and it is likely also involved in the third type of response to a threat, which is “freeze.” In the brain norepinephrine energizes the circuit-building process by adding phosphate molecules to a nerve cell receptor called GluR1. The phosphates help guide the receptors to insert themselves next to a synapse.
So when the emotionally-charged brain needs to form a memory, the nerves have plenty of available receptors to quickly adjust the strength of the connection and lock that memory into place.
The researchers targeted the GluR1 receptor after discovering that if it is disrupted in mice, the little creatures develop spatial memory defects. They tested the idea by either injecting healthy mice with adrenaline or exposing them to fox urine, both of which increase norepinephrine levels in the brain.
They then analyzed the brains of the mice and found increased phosphates on the GluR1 receptors and an increased ability of these receptors to be recruited to synapses.
When the researchers put mice in a cage, gave a mild shock, took them out of that cage and put them back in it the next day, mice who had received adrenaline or fox urine were likely to “freeze” in fear, compared with mice who had not been exposed to the adrenaline or fox pee. This implies an enhancement of their memory of the cage and its unpleasant associations.
In a similar experiment with mice genetically engineered to have a defective GluR1 receptor, adrenaline injections had no effect on mouse memory. So this provides us with further evidence of the “priming” effect of norepinephrine on the receptor.
There has been a lot of recent interest in using medications like beta-adrenoreceptor blocker propranolol – which prevents some of the actions of norepinephrine – to prevent the development of PTSD in people who have been exposed to extreme trauma, and this research may provide the scientific basis for this kind of therapy.
On the other hand, this research leads me to predict that people with overactive GluR1 receptors may be constantly curious about their environment, but also likely to be chronically anxious and more likely to develop PTSD.
We have known for years that propranolol and other beta-blockers may attenuate some of the physical symptoms associated with anxiety. Most people had assumed that the medicine worked by reducing heart rate, shaking and sweating. But experienced clinicians usually find that beta blockers that cross the blood/brain barrier work best, and it may well be that these drugs also have direct actions in the brain itself.
“Recollection is the only paradise from which we cannot be turned out.”
–John Paul (a.k.a. Johann Paul Friedrich Richter, German Novelist and Humorist, 1763-1825)
“The existence of forgetting has never been proved: We only know that some things don’t come to mind when we want them.”
–Friedrich Wilhelm Nietzsche (German Philosopher, 1844-1900)
“The moment we find the reason behind an emotion … the wall is breached, and the positive memories it has kept from us return too. That’s why it pays to ask those painful questions. The answers can set you free.”
–Gloria Steinem (American Feminist, Political Activist and Editor, 1934-)
Nutrition, Learning and Memory
We have talked about the burgeoning data linking food with mood, behavior and cognition.
I have just seen a new study that really adds to our knowledge and contributes information that we can all use.
Scientists in Europe, Australia and Indonesia have published data in the American Journal of Clinical Nutrition suggesting that nutrition can improve verbal learning and memory in schoolchildren.
This study was undertaken by the NEMO study group (Nutrition Enhancement for Mental Optimization) that consists of the Unilever Food and Health Research Institute (Vlaardingen, The Netherlands); CSIRO, Human Nutrition (Adelaide, Australia) and the SEAMEO-TROPMED Regional Center for Community Nutrition, University of Indonesia (Jakarta Pusat, Indonesia).
It was a 12-month study of 780 children in Australia and Indonesia in which the researchers evaluated the effects of adding a specific vitamin and mineral mixture to a daily drink.
The study population consisted of 396 well-nourished children in Australia and 384 poorly nourished children in Indonesia. In each country, the children were randomly allocated to one of four groups, receiving a drink with either:
- A mixture of micronutrients (iron, zinc, folate and vitamins A, B-6, B-12 and C)
- Fish oil (DHA and EPA)
- Both the micronutrient mixture and the fish oil
- Nothing added, i.e. placebo
In Australia, children who received the daily drink with the added vitamin and mineral mixture performed significantly better on tests of mental performance tests than children in a control group who received the drink but without added nutrients. In Indonesia a similar trend was observed, but this time only in the girls.
After twelve months, children in Australia who received the drink with the nutrient mix showed higher blood levels of these micronutrients, which means that their bodies were taking up the nutrients. In addition, they performed significantly better on tests measuring their learning and memory capabilities compared to children in the other groups. A similar trend was observed in Indonesia, but only in the girls. The addition of fish oil to the fortified drink did not conclusively show any additional effects on cognition.
This study adds to the mounting evidence that nutrition plays an important role in cognitive development in children, even in children who are enjoying a “normal” diet. Deficiencies in iron and iodine have been linked to impaired cognitive development in young children for over a century and there is now emerging evidence that deficiencies in zinc, folate and vitamin B12 may each compromise mental development in children. More recently, fish oils (EPA, DHA) have also been linked to child cognitive development.
Most previous studies have focused on deficiencies in single nutrients in young age groups, despite the well-known observation that the brain continues to grow and develop during childhood, adolescence and early adulthood. Little is known about the role of nutrition on mental development after the age of 2. In addition very other few studies have looked at the effect of offering a mix of nutrients. Until this study, there were very few randomized controlled intervention studies assessing the impact of a multiple-micronutrient intervention on cognitive function in schoolchildren.
The investigators recommend further research to investigate the exact role of DHA and EPA in healthy school-aged children. Another research focus is the further optimization of cognitive development tests with respect to their validity and sensitivity across cultures. The scientists suggest that the smaller effects of the vitamins and minerals in Indonesia could be a result of a lower sensitivity of the cognitive tests in that country.
This research raises many interesting points:
- Is it possible that the healthy Australian diet is actually nothing of the sort?
- Is it possible that if the diet is adequate, that “super-nutrition” can help a child to exceed his or her potential?
- Are there key ages when nutrition can help, or is the effect maintained across the age range?
- Does nutritional supplementation have a long-term impact on a child?
- Have we even found the optimal mixture for child cognitive development? Might higher amounts of any nutrients – particularly fish oils – produce better effects, or might they be toxic, as we saw in the case of vitamin A supplementation?
- Are we using the correct cognitive development tests to pick up changes in different cultures? As an example, could the smaller effects of the vitamins and minerals in Indonesia be a result of a lower sensitivity of the cognitive tests in that country? Or is it that the children are also missing out on some other trace nutrients?
Many questions, but the take home message is this: careful nutritional supplementation may have considerable benefits to a child, even one growing up in an affluent culture.
“Learning is a weightless treasure you always carry easily.”
–Chinese Proverb
Sleep and Memory
When I was a child and I had to learn something, I was always encouraged to read things one last time before I went to sleep. Now there is some research to indicate that this was excellent advice.
We have known for decades that sleep helps improve memory for procedural tasks, such as learning a new piece on the piano. But nobody has known for sure whether sleep helps other types of memory.
A study that presented at the 59th Annual Meeting of the American Academy of Neurology (AAN) in Boston, Massachusetts showed that declarative memories — memories for facts and events in time — become more resistant to interference during sleep.
To test whether sleep strengthens declarative memory in the face of interference, a research team led by Dr. Jeffrey Ellenbogen from Harvard conducted a study in which 48 people between the ages of 18 and 30 were divided into 4 groups:
- A wake group without interference
- A wake group with interference
- A sleep group without interference
- A sleep group with interference
Each group was taught the same 20 pairs of words in the initial training session. The wake groups were taught the word pairings at 9 AM and then tested on them at 9 PM, after 12 hours of being awake. The sleep groups were taught the word pairs at 9 PM and tested on them at 9 AM, after a night of sleep.
Just before testing, the interference groups were given a second list of word pairs to remember. The first word in each pair was the same on both lists, but the second word was different. The idea was that this would test the brain’s ability to handle interference. The interference groups were then tested on both lists.
The investigators found that subjects in the sleep groups had superior recall, when compared to those in the wake groups. The difference between the sleep and wake groups was greatest when the subjects were tested after interference (76% vs 32% of words recalled correctly in the sleep group vs the wake group. This result was statistically impressive: P < .0001).
This is important research: not only does it help us advise people on how and when to study, but it will likely have important implications for our understanding about how memories are laid down and encoded in the brain.
Brain-Derived Growth Factors and Bipolar Disorder
As we are learning more about the plasticity of the brain, and the way in which new neurons can continue to grow throughout life, there is a great deal of interest in factors that stimulate the growth or development of neurons. This is particularly important in condition like schizophrenia and bipolar in which cognitive decline may occur.
Researchers from Portugal presented some interesting new data (NR68) on Monday at the 2007 Annual Meeting of the American Psychiatric Association in San Diego, California.
Genetic and pharmacological studies have suggested that brain-derived neurotrophic factor (BDNF), one of the most common neurotrophic factors in the brain, may be associated with the pathophysiology of bipolar disorder. The data has been a bit of a mixed bag: previous studies have suggested that BDNF may be associated with either a worse or better neurocognitive outcome in tests of frontal lobe function.
The researchers examined 28 people with bipolar disorder whose mood was currently normal: i.e. they were euthymic, and they compared them with 25 healthy volunteers. They measured BDNF levels and performed a battery of neuropsychological tests.
The people with bipolar disorder had clear evidence of problems with attention and executive function even when their mood was normal. However it does not seem to have much to do with BDNF: the levels were the same in both patients and healthy volunteers. There was an association between BDNF levels and memory in people with bipolar disorder. This makes sense: BDNF has been implicated in the formation of memory traces in the brain.
What this means is that problems of attention and executive function are likely to be trait-markers of bipolar disorder, while BDNF levels may be a state-related biological marker.
It is interesting how the wheel keeps turning: the person who first differentiated dementia praecox (schizophrenia) from manic depression (bipolar disorder) was Emil Kraepelin. He originally said that people with dementia praecox became worse over time, because of progressive cognitive decline, while people with manic depression did not. When he passed away in 1926 he was working on a whole re-visioning of mental illness, saying that the two could not be so clearly differentiated, because cognitive decline could occur in either illness.
Many pharmaceutical companies are looking into the possibility of improving cognition in major mental illnesses, but there are also a great many non-pharmacological interventions that can be done to help cognition in people with major mental illness.
Genes, Culture and Aging
The study of genetics is becoming ever more interesting. Not only have we gone well beyond the nature/nurture debate, but also there is more and more interest in genetic influences on culture and vice versa: the way in which culture impacts gene expression. It is also clear that our brains are amazingly plastic: nutrition, emotional environment, education and experience all impact brain development.
Now it appears that culture does indeed affect the brain.
Westerners and East Asian people process visual information differently: Westerners preferentially process objects, while Asians tend to pay more attention to contextual information. In studies of semantic organization, Asians associate pictures based on functional relationships, for instance grouping together a mother and her child based on maternal relationship. Westerners based their associations on physical features and categorical membership, such as grouping together a woman and a man because they are adults. These differences may be changing as young people in Asian cultures are becoming more westernized.
New research has found that the aging brain reflects cultural differences in the way that it processes visual information. This study “Age and culture modulate object processing and object-scene binding in the ventral visual area” is published this month in the journal Cognitive, Affective & Behavioral Neuroscience. This paper (which can be downloaded here) and another published by the same group in 2006 are the first to demonstrate that culture can alter the brain’s perceptive mechanisms.
The research is the result of a collaboration between Denise Park’s group from the University of Illinois and Michael W. Chee, of the Cognitive Neuroscience Laboratory, SingHealth, in Singapore. The researchers conducted an array of cognitive tests on study subjects at their facilities in the U.S. and Singapore, and used identical functional Magnetic Resonance Imaging (fMRI) scanners at both sites. Their analysis involved 37 young and old East Asians, and 38 young and old Westerners. They found significant cultural differences in how the older adults’ brains responded to visual stimuli.
As Professor Park said,
“These are the first studies to show that culture is sculpting the brain. The effect is seen not so much in structural changes, but at the level of perception.”
We have known for decades that East Asians and Westerners process visual information differently. A paper in 1972 reported that East Asians are more likely to pay attention to the context and relationships in a picture than are Westerners, who more often notice physical features or groupings of similar subjects.
More recent research, which analyzed the eye movements of East Asians and Westerners viewing identical images, found that Westerners were more attentive to central, or dominant, objects, while East Asians paid more attention to the background, or scene.
Last year the team reported differing patterns of neural activation in the brains of East Asians and Americans shown identical pictures. The Americans showed more activity in brain regions associated with object processing than the East Asians, whose brains showed more activity in areas involved in processing background information.
The new study takes this work further, comparing neural responses to visual stimuli in young and old adults in both cultures. These are some of the pictures they used in the experimenets:
The researchers found that all four groups – young and old East Asians; young and old Americans – processed background information in part of the brain called the parahippocampal gyrus: a region that is vital to memory encoding and retrieval. As expected, older adults in both cultures had less ability to use “binding mechanisms” – the ability to connect a particular object to its background – in the hippocampus. The older people also had diminished object processing in the lateral occipital cortex.
The most striking finding was that the “object areas” of the brains of older East Asian subjects responded much more weakly to novel stimuli than did those same brain regions in the older Americans. For the older East Asians, a lifetime of attention to the backgrounds, or context, of pictures eventually showed up as a diminished response in the part of the brain that keeps track of foreground objects.
One of the best ways of keeping the brain healthy is with cognitive cross training: doing things like crossword puzzles, but also doing things that exercise other cognitive muscles, like playing the piano. This research would suggest that the exact strategies that we should use will be different in native-born Asian and western-born people. Something to factor in the next time that we get some advice about how to keep the brain young for as long as possible.
Cognitive Brain Health Test
One of the blogs that never fails to provide me with some food for thought is Zack Lynch’s Brain Waves.
He has just alerted his readers to a very interesting resource.
The Brain Resource Company launched a free, confidential, 40-minute cognitive brain test in partnership with the Alliance for Aging Research. The company is offering the test at no cost until May 14, 2007.
When you first click on the link for the test, you are taken to a page on Brain Health with a great many links.
I am extremely familiar with the literature on the brain, aging and cognition. So on your behalf, I passed a critical eye over the material. I was really pleased with it. I have one or two very minor quibbles, and one or two of the links are not working yet, but overall the information is excellent and above all reliable.
One thing about doing the test is that it needs for you to be using Windows. So we Macintosh users are left out in the cold. But the test is well worth doing, so if you are a Macintosh user, you might want to see if you can borrow a Windows machine for an hour.
“Most people would sooner die than think; in fact they do so.”
–Bertrand Russell (Welsh Mathematician, Philosopher, Pacifist and, in 1950, Winner of the Nobel Prize in Literature, 1872-1970)
“The longer I live, the more beautiful life is.”
–Frank Lloyd Wright (American Architect, 1867-1959)
Memory is a Key to Visualization
Most of us have been told something about the potential benefits of visualizing an outcome, and I know from working with many athletes, chess players, dancers and even surgeons, that most are very good at visualizing exactly what they want and where they are going to be.
I have recently talked about the ways in which encoding of memory for faces and the crucial role of memory in creating images of the future.
There is some important confirmatory research from the Wellcome Trust Centre for Neuroimaging, University College in London. A study led by Dr Eleanor Maguire has just been published in the Proceedings of the National Academy of Sciences. It involved five participants with dense amnesia caused by damage to the hippocampus on both sides of the brain.
The researchers asked the participants – and a control group without amnesia – to imagine several future scenarios, such as visiting a beach, a museum and a castle, and then to describe what the experience would be like. They then analyzed the subjects’ comments sentence by sentence, scoring each statement based on whether it involved references to spatial relationships, emotions or specific objects.
All but one of the people with amnesia were worse at imagining future events than people with normal memory. Their visualizations of future events were more likely to be disorganized and lacking in emotion.
Here is a quotation from one of the subjects:"It’s not very real. It’s just not happening. My imagination isn’t…well, I’m not imagining it, let’s put it that way."
The hippocampus does not simply relive past experiences, it also supports our ability to imagine any kind of experience including possible future events.
This is yet more evidence against the idea that memory works like a kind of video camera, passively recording your life. It is a far more dynamic process that include your own beliefs, emotions and expectations.
“A rock-pile ceases to be a rock-pile the moment a single man contemplates it, bearing within him the image of a cathedral.”
–Antoine de Saint-Exupéry (French Aviator and Writer, 1900-1944)
“All acts performed in the world begin in the imagination.”
–Barbara Grizzuti Harrison (Italian-America Journalist, Essayist and Author, 1934-2002)
“I visualize things in my mind before I have to do them. It’s like having a mental workshop.”
–Jack Youngblood (American Football Player and Member of the Pro Football Hall of Fame, 1950-)
How We Plan the Future
One of our most remarkable abilities is our capacity for creating a mental picture of events that have not yet happened. It certainly appears that many animals can do something similar, but the human ability to wait and to plan seems to be almost unique. Though with all the recent advances in our understanding about the emotional and cognitive skills of many animal species, I am wary about making too many claims about human specialness.
There is some fascinating research in today’s issue of the Proceedings of the National Academies of Sciences.
Investigators from Washington University in St. Louis, have performed a set of experiments that will not only help us better understand what goes wrong in some diseases, but may ultimately help all of us to become better at visualizing.
They compared the functional MRI scans of 21 healthy volunteers when they were asked either to vividly imagine future events or to recollect past memories.
The images showed clear differences between imagining a birthday already experienced and a birthday yet to come.
In particular, when looking ahead, there were three particular areas of the brain that became activated – the left lateral premotor cortex, the left precuneus and the right posterior cerebellum. These areas of the brain are already known to be involved when we imagine executing body movements, suggesting that when the brain is thinking about the future, it does so in terms of distinct movements and actions that will happen at that point.
The research provides powerful support for the idea that memory and thought about the future are highly interrelated and may help explain why future thought may be impossible without memories.
Other research has shown that when volunteers are asked to think about playing baseball they activate the part of the brain involved in swinging the arm. You will now see the link with the item that I posted yesterday about learning to tango!
These findings are consistent with observations on people who have sustained damage to these regions of the brain: they lose the ability to think ahead. There is a small amout of data to suggest that some of these same regions do not function properly in some people diagnosed with antisocial personality disorder, most of whom have a reckless disregard for the consequences of their actions.
People with depressive disorders often find it very difficult to generate a positive image of the future, in part because their memory is impaired by the depression.
In classes we have also found that if people maintain complete stillness while visualizing it is quite different from moving and doing the physical actions as you visualize.
Try it for yourself and see what I mean.
“Man can only become what he is able to consciously imagine or to “image forth.”
–Dane Rudhyar (a.k.a. Daniel Chenneviere, French-born American Composer, Theosophist and Astrologer, 1895-1985)
“I am thought. I can see what the eyes cannot see. I can hear what the ears cannot hear. I can feel what the heart does not feel.”
— Peter Nivio Zarlenga
Dreaming and Memory
As I am writing this, one of the cats is fast asleep on my desk and clearly involved in a dream that involves running and jumping. It looks as if she’s having fun.
I’ve been fascinated by dreams and dreaming ever since I read Sigmund Freud’s The Interpretation of Dreams as a teenager. For over a century, people have speculated about a link between dreams and memory, and another book that influenced me as a youngster was called Dreaming and Memory by Stanley R. Palumbo. These books were firmly rooted in a psychoanalytic framework, and I’ve always been interested in trying to reconcile psychoanalytic and neurological views of our mental life.
So I was intrigued to see an article that just came out in Nature Neuroscience.
Almost six years ago, Matthew A. Wilson at the Massachusetts Institute of Technology (MIT), in Cambridge, Massachusetts demonstrated something very interesting. Rats formed complex memories for sequences of events that they had experienced while they were awake. These memories were replayed while they slept, perhaps reflecting the animal equivalent of dreaming.
These replayed memories were detected in the hippocampus, a region of the brain that is associated with memory. But the researchers were not able to determine whether they were accompanied by the type of sensory experience that we associate with dreams-in particular, the presence of visual imagery.
In the latest research Wilson who is professor of brain and cognitive sciences at MIT’s Picower Institute for Learning and Memory, and postdoctoral associate Daoyun Ji looked at what happens in rats’ brains when they dream about the mazes they ran while they were awake. They recorded brain activity simultaneously in the hippocampus and the visual cortex, and demonstrated that replayed memories did, in fact, contain the visual images that were present during the running experience. Neurons that are activated when the animal experiences an event while awake are reactivated during sleep.
There is another piece to this research: the regions of the cerebral cortex that processes input from the senses and the hippocampus communicate with each other during sleep, leading us to speculate that this process reinforces and consolidates memories.
As the authors write, "These results imply simultaneous reactivation of coherent memory traces in the cortex and hippocampus during sleep that may contribute to or reflect the result of the memory consolidation process."
This is of great practical importance: it strongly supports the idea that adequate sleep is necessary to consolidate memory.
When I was a child my parents taught me to read through all my schoolwork just before I went to bed, even if I was tired. Work in psychology has shown that this is often the best way of memorizing factual material, and this new research shows us why.
“Waking is long and a dream short; other than this there is no difference. Just as waking happenings seem real while awake, so do those in a dream while dreaming. In dream the mind takes on another body. In both waking and dream states thoughts, names and forms occur simultaneously.”
–Ramana Maharshi (Indian Hindu Mystic and Spiritual Teacher, 1879-1950)
“The light of consciousness passes through the film of memory and throws pictures on your brain. Because of the deficient and disordered state of your brain, what you perceive is distorted and colored by feelings of like and dislike. Make your thinking orderly and free from emotional overtones, and you will see people and things as they are, with clarity and charity.”
— Sri Nisargadatta Maharaj (Indian Spiritual Teacher and Exponent of Jnana Yoga and Advaita Doctrine, 1897-1981)
