How do we remember?

If we start from the idea that cognitive system receives sensory and environmental stimulation every second, of every minute, of every hour of the day, then we have a rough idea of how much information our brain processes continuously, even during sleep.

In comparison, if we keep a computer turn on with continuous data analysis during, let's say... 20 years, there will be a moment, regardless of storage capacity and RAM memory, when it will have to reset and  probably lose some data processing.

But the brain in general, unless there is a neurological condition, or a poor diet or as a result of a stroke, can not afford to lose data. However, everyday conditions as stress or lack of attention motivated can erase data, even two seconds of having access to the information. Who has not been forgotten a phone number?, or just forget why you  got up to go to another room to take some object?.

It seems that in general there should be a error margin on recovered information because sometimes we can only have access to pieces of information and some other, you get the information by association.

But brain, has also an application called cognitive economy, and it's the way to streamline the system and make it capable to work with minimal information and help it to relate with other nodes of information. In this sense it's possible to group events, for example, there is no need to remember all the information about a topic, because it can be related to what is said or heard. Let's say a list all the objects found in an office or a bedroom. Usually we don't mix information from other categories, such as mosquitoes or green elves, unless that's part of the environment (Chen, Loftus, Lin, He, Chen Li, Xue, Lu and Dong, 2010).

Personally my favorite example about this application is: we never expect to mix dirty socks in the drawer of clean spoons.

At this sense, the way some people have explained the process, it's saying that memory is distributed in volumes of an encyclopedia, where each memory has a place within the private library, the way the volumes are located and how they are classified is defined personally. The same memory can be in a classification for a person but in a different place for someone else even if they have experienced the exact same event (Sagan, 2001).

That is why understanding the cognitive economy, allows the system to use information efficiently, and all this knowledge has led to the development of electronic systems with much more rapid data processing and order.

But then, it seems logical that there are different stages or processes in memory, because we can talk about a consolidated memory where we can find aspects of personal life or learning that we never forget, like riding a bicycle or driving a car (when you have the ability) and on the other hand, there are aspects of memory in the here and now.

There is a complete group of research about long-term memory, some call it an episodic, and on the other hand, researches describe a memory of here and now, it's called short-term, but in general is known as working memory (Contreras Ruiz and Cansino, 2005, Burin and Duarte, 2005).

The long-term memory or episodic, from the neurological point of view requires morphological and functional changes in synaptic transmission, which in turn requires the open and closed gene activation and synthesis of proteins that allow the flourishing of synaptic buttons (Ruiz Contreras and Cansino, 2005).

These memories are rooted, which can be very personal issues or behaviors that are performed automatically, also known as habits.

When someone asks: what's your name?, it's not required to open the system information to find the answer, you automatically will respond my name is ...

But for making this  possible, information must be consolidated, that's why repetition is an important element in the process, but not only in linguistic form, since it can be involved more than one sensory system. How many times have you tasted an orange  and knew without doubt, that it was an orange?, The relationship of the word orange is given from the taste, smell, shape, color, texture, size ... the relation of all that with the word is what is known as orange.

The short-term memory or operational work is what we use routinely when someone gives us information on how to get to a place or just for specific instructions. This information is much more volatile than long-term memory; it depends of the attention to keep it in the system.

This memory in general is linked with language, as it tries to retain information through words even when the information is obtained from any other sensory modality. In addition, it looks more related   to closed genes since it depends on the holding capacity of each individual (Morgado Bernal, 2005).

Moreover, most models of working memory separate two types of sources: active mechanism  processing,  that are managed by attentional resources, for example, pay attention to something specific, and  there is  in addition,  passive mechanisms , where there is a clear intention to remember. Although, these passive forms may arise through the association of ideas or stimuli.

It is also thought, that the mechanisms are primarily linguistic processing, as when trying to remember something we read or hear, but it can be visual as one of the main sources of information and also poses a spatial mechanism, which gives us the ability to make a movement.

In this sense the brain areas involved range from visual, motor and language in all its forms (Burin and Duarte, 2005).

On the other hand, some researchers have tried to understand the mechanism of consolidation, as some tasks seem to give priority to a serial system, where information must have some specific order, hence the series should be ordered and sequenced in a particular way, an example of this is the multiplication tables, while other de tasks does not require order, but if the association (Sackur and Dehaene, 2009).

There is a model called dual categorization, where both processes can be used depending on the requirements of the task (Glöckner and Witteman, 2009). This may occur when someone needs to make decisions using insufficient information.

But once the information consolidated, it is necessary to recover it, otherwise it's not possible to know if it exists or if we saved it correctly. Although usually it's seen as a part of the memory, actually this process uses different areas of the brain and specific mechanisms. Basically it is defined as the process of extracting information stored in memory in response to a task (St. Clair Thompson, 2010), but memories doesn't come specifically by need, because sometimes they come at once, linked with other topics.

Areas that are in charge of this process are the hippocampus and prefrontal cortex. During the recapitulation of events  our  hippocampus receives information from the neocortex and sends efferent projections, which suggests that the hippocampus is the director who receives and seeks; provides an order  to all information and at the end decides  the output source, which can be a word, a movement or shape (Ruiz Contreras and Cansino, 2005).

The process will let us remember only the information that we will  use steadily, otherwise will be forgotten, except in the case of information linked  with emotion, which explains the flashbacks, as in the case of people who have suffered any trauma and gives as a result a memory that is virtually indelible. And on the other hand, a memory problem can also be lack of consolidation or retention of information, such as when studying for hours for an important exam and recovery time is simply not capable of displaying all information.

These two examples are just a little part of the challenge trying to understand the whole process of memory, because laboratory studies are far from emulating the multi-level activity that takes place daily in every brain, and how it uses and manage information. Hence the process of knowledge-based on economy provides some order to the amount of information that sometimes is handled.

That is why information apparently is grouped in related areas, and all information on how to write is in a drawer and the information used to get home is in a different drawer. But it is also true that sometimes distant areas are related, because this allows creativity and problem solving (Weimer and Palermo, 1974).

But, please, you don't need to worry, because your brain works 24 hours a day for 7 days a week, even while you sleep, deleting unnecessary information which allows more space for more events and this makes  possible  our function in the hectic and fast world of information. On the other hand, the brain has learned to use tools that are designed for those who feel that the memory is expandable.

Yes, there is a cult for all the tools, applications and toys, every day there is a new device or an application for everything imaginable and unimaginable, but we can't  forget that those gadgets depend on batteries, connections and servers with a memory finite, and the disaster is massive when those systems are violated or space is not enough. In contrast, your brain can always expand your ability to learn strategies that will make the process easier and only asks for food, rest, environmental stimulation and a little of socialization.

References

Burin, D. y Duarte, AD. (2005) Efectos del envejecimiento en el ejecutivo central en la memoria de trabajo. Revista Argentina de Neuropsicología. 6. 1-11.

Chen, C., Loftus, E., Lin, C., He, Q., Chen, C., Li, H., Xue, G., Lu, Z., and  Dong, Q. (2010) Individual differences in false memory from misinformation: Cognitive factors. Memory. 18 (5) 543-555.

Glöckner, A. and Witteman, C.  (2009) Beyond dual- processes model: A categorization of processes underlying intuitive judgment and decision making. Thinking and reasoning. 16 (1) 1-25.

Morgado Bernal, I. (2005) Psicobiología del aprendizaje y la memoria. Cuadernos de comunicación e información. 10 (2) 221-233.

Ruiz Contreras, A. y Cansino, S. (2005) Neurofisiología de la interacción entre la atención y la memoria episódica: revisión de estudios en modalidad visual. Rev. Neurol. 41 (12) 733-743.

Sackur, J., and  Dehaene, S. (2009) The cognitive architecture for chaining of two mental operations. Cognition. 111. 187-211.

Sagan, C. (2001) Cosmos. Editorial Planeta. España.

St. Clair Thompson, HL. (2010) Backwards digital recall: A measure of short-term memory or working memory?. European Journal of Cognitive Psychology. 22 (2) 286- 296.

Weimer, W. and Palermo, DS. (1974) Cognition and the symbolic processes. Lawrence Erlbaum Associates. USA.

3D image: Juan Conde Tovany

Memory and language

Alma Dzib Goodin

When we talk about memory, in general is associated with the past and memories, however, memory has a lot to do with language, because while we structure a phrase, many temporal associations are carried out either at present, past or future. I don't think is necessary explaining too much this aspect, since everybody suffers with   verbal conjugation at the first years of formal education.

And this is because the brain is constantly influenced by spatial and temporal patterns across of all the senses (Hawkins and Blakeslee, 2004), and then we say, of course, I had read that!, or it tastes like ... and ate it at....

During a conversation, is important to pay attention if you are talking in present tense, past or future, since this depends on the structure and meaning of the sentence. Of course, this is not knowledge that a newborn uses from day 1, it's one of the many tasks to be learned over time, related with brain maturation, environmental demands and verbal skills, some of them imposed by genetics.

Then, how can a brain work with multitasks?. It does this primarily by electrical impulses that travel through the synaptic connections, that are fired every 5 milliseconds, which work  parallelizing tasks, I mean, it does many things at once and at different levels, it performs tasks consciously and others unconsciously and also pay attention to the environment and the details (Hawkins and Blakeslee, 2004; Glöckner and Witteman, 2009).

But if focus at the language, the maximum achievement of the neocortex is the grouping of ideas, which can occur in prospective, this is, think ahead. During a conversation, we can predict what the speaker will say or do, this is an important process not only for language, but when we are driving a car, or watching a movie, which is an aspect of memory (Brewer and Marsh, 2010).

And of course, it's not possible ignore the great speed with which it is possible to remember something when the stimulation and the conditions are right. This is called reaction time in laboratory experiments, but that is pure fun when we play table games that require a unique quick response, which of course is a process that requires an active memory and familiarity of stimuli (Brewer and Gimbel, 2011).

But I guess, you reader   know your strengths in aspects of memory. Despite what teachers say that we must remember everything they say, our brain has something else in mind (that is literally). And while some people have better visual memory, and can remember what they saw or read just once and remember the name of the author of the book or article they read, there are some others who remember much better if the stimuli are auditory, and they learn to read loud to retrieve information better. There are also those who remember motor tasks and they are able to remember things when they do a movement. And I can not forget to mention my deep admiration for those who can recognize flavors, or the aroma of fine wine or a good meal.

Tasks that seem simple become complex when we try to explain them, for example, the recognition of faces is a complex but essential aspect in life. This process begins in the first days of life; it depends on the maturity of the oculomotor muscles and provides assurance that the caregiver is always the same. But it’s not the only one, because the sense of smell provides protection while babies develop the ability to focus objects. Thus, little by little they are making a complex network of processes that, with no doubt, help  to let us to know that we talk to someone we  know.

So, How do you remember a face?, Is it remembered or recognized?, this will be  another topic, that I will take as a  excuse to write again, but the fact is that  process is complicated: it starts with the rapid identification of the face, if it has similar racial characteristics, this can be a first  kind of identification, if not, you will have to considerate many details: the color of eyes, its location, shape, distance between them, the characteristics of each one and then the shape of the face, color, contour, form hair, color of the eyebrows, lips, cheekbones (Ewing, Pellicano and Rhodes, 2010), thus intersect other details such as whether the person is attractive, if we recognize that person and then, maybe we will try to find a  name in the library of memory, making a comparison  between face, name and a location where that person have seen  before.... and all that will be done in millisecond,

Of course, sometimes the process is not accurate, and the identification finishes with no an idea who is speaking with us. And even in that case, you can try some  clues as: if the other person knows or not my name?, the topic of conversation?, If I talk about this then I know this place, other clues can be the tone of voice, familiarity ... the system continues the search until it can  finds a positive recognition ... but you don't have to feel shamed if all the process fails, it may be easier to recognize the voice, or other aspects, such as recognizing the other person car, bag, shoes? ... each person is inclined to recognize objects in the environment in a distinctive manner.

In general, though not exclusively, men are capable of distinguishing details between cars, a Porsche and a Lamborghini are not equal, a Prius and Acura are not similar at all, and Who can confuse a beetle and an MDX?. Personally, I only know that cars have wheels and need gasoline, sometimes.

But vision is not always the main form of recognition. I used to feel worry  the first few times I waited for him at the airport, for who is now my husband, I was not able to make a mental image of his face. I only remember he had blue eyes and red hair. So I just could wait for someone with these features, but it was a challenge. The only consolation was that maybe he could recognize me, and when that happened, his voice did not let me any doubt, he was the right person.

Of course, once the recognition is done, the face has a name ... the vision is related to language when is trying to tie a memory. When everything matches, it's not necessary more searching at the data banks, all features are tied, but the issue is more complex than it seems, because although all that is accomplished in a few seconds, the search for the information needs of different brain areas and all information is concentrated in the hippocampus (Ewing, Pellicano and Rhodes, 2010).

If a task as simple and everyday as face recognition takes so much work, just enough to imagine the process of recognition of words, tense, voice tones, volume, modulation and content during a conversation.

Starting from the idea that thought is private and language is public, and then speak is making public the private. (In so many years, I can not remember from whom I learned this in my first years at university). However, both processes are completely different. But this  is conceivable under the multi-tasking system, because while we feel good or bad with  the external temperature, we plan activities for the next few hours or the next day, make a to do list, we feel hunger, we make mental notes of what to say on the next business meeting, we try to remember if we fed the cat and locked  the closet door or if we turn off the light ... the tasks can be endless, but, language only accepts the execution of a letter at a time, to form a word that is part of a sentence, to form an idea, and is able to link with the following (Weimer and Palermo, 1974).

We remember  what it was said, what is being said and what we are going to say,  or we can predict the next sentence, in studies  of laboratory, researchers try to see  separate processes, but in everyday life, they  are seemingly inseparable.

And all this has been learned in daily interaction, even before a first word can be said, and when babies start practicing, of course they make verbal mistakes, because their memory is not consolidated yet. But nobody cares about these failed attempts; adults encourage toddler to try it again, and again.

Different brain areas are used depending the kind of speech, for example, if we are talking about colors, there is an isolated portion of the brain that needs to be involved, but if we are trying to do a voice recognition, or shapes, other areas must work together, because all processes are separated, and then re grouped into the brain, but yet it's not possible to understand how this is possible.

That's why learning in children, can not be based only in isolated memorization and meaningless, specially because there is a specific area where all information must be joined and summarized to give sense to the world. But on the other hand, remembering can be   too inconvenienced because when an area of the brain is over specialized, it means another area is compressed, and this can be the case of talented or gifted children for whom the neocortex is the raw material in exchange for neglecting the social skills (Herbert, 2005).

The clearest case of this are  people with a diagnosis of Savant Syndrome, whom are able to remember very little details of what captures their attention, but sometimes with an IQ less than 50 (Winner, 1998).

Remembering then, depends on the attention, of environmental stimulation and the hippocampal ability to recognize tasks (Brewer and Gimbel, 2011). Does it seem complex?, Well, if you  try to explain it using only electrical impulses, bio chemicals, neural connections and a little knowledge of neurophysiology, if it is, but it's an activity that every brain does every  day, every second each day of our lives ...

Alma Dzib Goodin 

If you would like to know more about my writing you can visit my web site:
http://www.almadzib.com

References

Brewer, G. and Marsh, RL. (2010) On the role of episodic future simulation in encoding of prospective memories. Cognitive Neuroscience. 1 (2) 81-88.

Brewer, JB. and Gimbel, SI. (2011) Reaction time, memory strength, and fMRI activity during memory retrieval: Hippocampus and default network are differentially responsive during recollection of familiarity judgments. Cognitive Neuroscience. 2 (1) 19- 26.

Ewing, L., Rhodes, G. and Pellicano, E. (2010) Have you got the look? Gaze direction affects judgment of facial attractiveness. Visual cognition. 18 (3) 321-330.

Glöckner, A. and Witteman, C.  (2009) Beyond dual- processes model: A categorization of processes underlying intuitive judgment and decision making. Thinking and reasoning. 16 (1) 1-25.

Hawkins, J., and Blakeslee, S. (2004) On intelligence. Times Books. USA.

Herbert, M. (2005) Large brains in autism: the challenge or pervasive abnormality. The Neuroscientist. 11 (5) 417-440.

Molinaro, N., Conrad, M., Barber, H. and Carreiras, M. (2010) On the Functional Nature of the N400: Contrasting effect related to visual word recognition and contextual semantic integration. Cognitive Neuroscience. 1 (1) 1-7.

Pendarvis, E., Howley, A., & Howley, C. (1990) The abilities of gifted children. Prentice Hall. USA.

Weimer, W. and Palermo, DS. (1974) Cognition and the symbolic processes. Lawrence Erlbaum Associates. USA.

Winner, E. (1998) Uncommon Talents: Gifted Children, Prodigies and Savants. Scientific American Presents. 32-37.

3D Image: Juan Conde Tovany

The relationship between memory and attention

Memory and attention are clearly related because process of attention has its beginning when brain remembers what senses capture. When someone pays attention to a meal, the chemical sense of taste tries to recognize all flavors, trying to separate every one of the components to be able to say this taste like...

When attention is required from the visual system, we must remember the spatial location of objects, colors, shapes and composition of structures of what we see, and sometimes speed and movement are required (Delaney, Nghiem and Waldum, 2009). But the process becomes complex when after watching something for a while, we have to reply specific questions about those object or their composition. Of course, more elements are involved at the scene; more complex will be to determine what we looked.

Please, analyze the image above, pay attention to colors and shapes, recognize objects, examine the composition.

Do you recognize those birds?, do you know what are they walking on? where was taken the photograph?.

Attention must be based on prior knowledge of the elements or otherwise it would be difficult to say if persons can recognize what they see (Ruiz Contreras and Cansino, 2005). Hence, brain requires complex interactions between episodic and working memory, also called long-term memory, which allows access to information on the system. The principle has been explained as a review of the files in the brain, ready to be used at need (St. Clair Thompson, 2010).

But then, how does emerge this system called memory so complex and delicate sometimes, in the evolutionary process?.

Memory, as well as other basic processes (sensation and perception, learning, motivation and emotion, thought and language) was designed to be used to keep survival of the species, I mean, it serves to keep us on the face of the earth. But it also fits the individual needs depending on the interaction with the enviroment (Killgore and Yurgelun-Todd, 2009).

At this sense we can say that memory process is flexible, and  some researchers have found recently  that their cells are renewable, mainly  showing that both the cells of the hippocampus that is where physical location is believed memory process, such as the olfactory bulb, are renovated, as well as skin and bone cells (Alvarez - Buylla and Garcia Verdugo, 2002).

This is the reason that memory requires consolidation. Try to remember these digits: 9, 3, 9. 0, 9, 2, 1, 7 ...

Learning is usually associated with memory, in fact the whole process is learning and memory, and of course,  both processes require attention, but how is the process? Do we remember first and then we learn? Or do we learn and then remember?. What do come first? Is the chicken or the egg?. From the standpoint of the brain, one relies on the other. I can say my name because I have learned it, so if someone shouts my name in the middle of a crowd, even with little effort, I will seek out who called me. But then what do babies have prior knowledge to remember?.

First of all, memory is a process found in other species, many studies about memory have been conduced with cats, and we all know that dogs can remember roads, people and smells; some species of birds can remember words, this is because a bigger and more evolved brain of specie will let them to create more complex interactions between processes.

We also know that  memory is located in the brain, specifically on an area called  hippocampus, which is part of what is called the limbic system, located exactly in the middle of the brain and is also home to the emotions. Hence there is a strong relationship between memory and emotion.

This relationship may  create incomplete memories, for example adults can remember the moment when a parent used some kind of punishment to reprimand misconduct. It is easy to remember the punishment and the pain, whether physical or emotional, but when ask: Why were you punished?, Usually the memory is much more vague. Misconduct didn’t produce pain; the punishment was the painful event.

Can you remember the numbers a little above on this article?, Do you remember the exact order?, Now ... can you remember them in reverse order? ...

When laboratory tests are made,  as in the psychometric tests, usually are used stimuli like remembering digits, words in order, relating words or numbers, but in normal life, the amount of stimulation is such that hardly can remember and pay attention to many events. Some decades ago, researchers believed that the magic number of memory was 7 ± 2 ... but if we remember 3 things now, sometimes is enough.

And in this age of information, where everything flows as Pentium 5 speed,  how can we remember the date, the appointment of 5 pm, our to do list, the task to tomorrow, someone's birthday, phone numbers and also set the snooze alarm?.

We learn to rely on equipments that we make life easy, such as Ipads, smart phones, the I phone, post sticks on our laptops,  because the brain is not expandable, it is confined in a finite space, therefore depends on the cognitive economy, and remember only important things, like where did I leave my cell phone?.

But for a newborn, things are different. Babies do not HAVE to remember their acts, they depend from the so-called primary instincts, for example, eat, sleep, defecate ... they do not have to remember, how breathing or if they need to sweat. Nature gave to species a complete equipment to survive, because the brain is capable of operating under minimum conditions, because is not fully developed. In fact, I think development is a never ending process, since the different areas begin the race to connect and create functional neuronal networks, to respond to the needs of the environment (Dzib Goodin, 2011).

The race to connect neurons, under the principle of the fittest networks and more repetitive task will survive and what is not discarded; this race begins before birth, but will be more evident during the first year of life. Of course, begins the development of what is known as white matter, which is nothing else than the way to conduct electrical impulses. This substance has been associated with processing speed and connectivity, defined as the ability to connect different brain regions effectively (Roberts, Anderson, and Husain, 2010; Tirapu-Ustárroz, Luna-Lario, Hernaez-Goñi, and García-Suescun, 2011).

As we grow, thanks to the interaction of the environment, will be created specific networks or circuits, hence even if two people live the same events, each one will remember or analyze them differently. Some further developed visual system and it will be easy to remember visual stimuli while others are more inclined to the sound.

The relationship between learning and memory, arises for a need to consolidate those things that become important, for example the way to go home, the name of the street where you live, your name, biking or driving a car, remembering the alphabet and the sounds associated with each sign, so do the numbers, the arithmetic relationship ... what we learn remains in the cognitive system, but if you also need it and is in constant use, this will consolidate it, and  if we add the fact that what we like and makes us feel good, and probably all those things will be repeated many times, this will create a strong neural network and may be difficult to change with time.

And this is because, habits are nothing else than consolidated neural networks, we do not have to think how to use a toothbrush, as soon as we get closer to where it is, we take it without thinking about what hand should do the work, we use it as best we can, we rinse and we put it in place without thinking of it.

You as an expert reader has not needed to think how recognize any sign of this writing, you know the sounds associated with, you joined them, understood them and gave meaning to the text. Nobody had to tell you, this is an A and this B, and this sounds like ... maybe this can explain better the relationship between learning and memory.

Can you remember the numbers that were read above in this paper?. Do not worry!, 98% of people fail to do so and in this case is a good sign, you paid more attention to the text. What do you earn remembering those numbers? Unless there is a prize of $ 3,000 is not worth using a portion of their cognitive processing on it.

Those useful aspects of sensory stimulation will be consolidated by our memory, which causes us a very strong emotion, or what enables us to survive. Who cares about how many numbers above?, Only those who have a brain injury,  and  suffer an obsession with numbers ... sometimes it's good to rely on electronic toys  to remind us things,  or physiological processes, to remember that it is lunch time.


Alma Dzib Goodin 

If you would like to know more about my writing you can visit my web site:
http://www.almadzib.com

Referencias

Alvaréz – Buylla, A. y García Verdugo JM. (2002) Neurogenesis in adult subventricular  zone. The Journal of Neuroscience. 22(3) 629-634.

Delaney, PF., Nghiem, KN and Waldum, ER. (2009) The selective directed forgetting effect: Can we forget only a part of a text?. The Quaterly Journal of Experimental Psychology. 62 (8) 1542-1550.

Dzib Goodin, A. (2011) Introducción a los procesos neurocognitivos: lenguaje, lectura, escritua y matemáticas. En  prensa. Servicios Editoriales Balam. México.

Killgore, WDS. and Yurgelun-Todd, DA. (2009) Cerebral correlates of amygadla responses during non-conscious perception of facial affect in adolescent and pre adolescent children. Cognitive Neuroscience. I (1) 1-11.

Roberts, R.E., Anderson, E. J., Husain, M. (2010) Expert Cognitive Control and Individual Differences Associated with Frontal and Parietal White Matter Microstructure. The Journal of Neuroscience. 30(50): 17063-17067.

Roberts, R.E., Anderson, E. J., y Husain, M. (2010) Expert Cognitive Control and Individual Differences Associated with Frontal and Parietal White Matter Microstructure. The Journal of Neuroscience. 30(50): 17063-17067.

Ruiz Contreras, A. y Cansino, S. (2005) Neurofisiología de la interacción entre la atención y la memoria episódica: revisión de estudios en modalidad visual. Rev. Neurol. 41 (12) 733-743.

St. Clair Thompson, HL. (2010) Backwards digital recall: A measure of short-term memory or working memory?. European Journal of Cognitive Psychology. 22 (2) 286- 296.

Tirapu-Ustárroz, J.,  Luna-Lario, P., Hernáez-Goñi, P., García-Suescun, I. (2011) Relación entre la sustancia blanca y las funciones cognitivas. Rev Neurol. 52 (12): 725-742.

Nore: 3D image: Juan Conde Tovany

          Photography: Alma Dzib Goodin