Similarity between Neurological and Yogic models of human memory

Neuroscientists have identified various types of human memory based on differences in cortical processing.   Sri Aurobindo classified human memory into three types.  Ancient Indian Yoga psychology works have made a distinction between various parts of memory(i.e. Chitta).   We will explore to determine if there is any correspondence between all these various classifications of human memory.

Neuroscience states that memory is held in various parts of the brain while Yoga psychology views mind (Chitta) as pervasive within the body, with memory viewed as an inherent part of the mind.   The neurological view of memory is derived from the fact that it lumps consciousness, mind and the brain together into one entity which is treated as being separate from the physical body.  By contrast, the Yogic model separates consciousness, the mind and the brain.  It states that consciousness is the substratum whose differentiations create mind, vital(life-force) and matter, and that the mind is not limited to the brain but forms a subtle/occult sheath of its own.  The brain in this case is a center for organization, ideation as well as communication with the senses.  We will ignore this dissonance on the location of memory and focus on finding similarities between the memory taxonomy which have been postulated by both sides.

First we will present the neurological view of memory, then the Yogic view of memory and then see if we can find some similarity.

Neurological view of memory

The neurological classification of memory is derived from functional imaging experiments as well as lesion studies, in which study of dysfunction offers insights into normal function[Tul].  Neurological experiments have identified the following types of memory.

  • Sensory memory
  • Short term memory
  • Long term memory which has two further sub-types :
    • Explicit/declarative memory
    • Implicit/non-declarative memory.

Sensory memory

This refers to the ability of the five senses to retain information of impacts. See wikipedia.

Short-term/Working memory

It refers to the memory which we hold in our mind while performing some task.   There is a distinction between working memory and short-term memory.   The latter is a theory-specific construct which lasts a few seconds while the former is a generic term.   I will use the former because I am unclear if short-term memory can correspond to anything in Yogic memory model given it’s relatively short duration.

Long-term memory

This refers to the memory which can last for a few days to a few decades.  This is further classified into explicit and implicit memory.  The distinction between explicit and implicit memory was uncovered due to lesions on the bilateral limbic association areas of the temporal lobe [KJS].  The figure below, from the Hippocampus book by Andersen et al [AM], gives a taxonomy of long-term memory.

Neurological memory model

Neurological memory model from the Hippocampus book (Andersen et al)

Explicit/Declarative memory

This refers to the conscious recollection of memory (see wikipedia).  Endel Tulving further refined this category into episodic (autobiographical) and semantic (facts) memories based on evidence of greater blood flow in the anterior portions of frontal lobe when the subject was thinking about autobiographical information, and greater blood flow in the posterior portions of the frontal lobe when thinking about generic information[SN].  Semantic memory refers to memory of facts (e.g. name the capital of a country) while episodic  memory refers to memory of events in one’s personal life.   Using lesion studies,  various areas of the brain which store different kinds of explicit memory have been identified.  The following table is a partial list derived from  book Principles of Neural science by Kandel, Jessell and Schwartz [KJS].

Area of brain Memory type
right hippocampus spatial orientation
left hippocampus verbal memory
median temporal lobe long-term new memory
occipital lobe Apperceptive agnosia: cannot draw an object but can name it.
posterior parietal cortex Associative agnosia : can draw an object but cannot name it.
inferotemporal cortex Prosopagnosia : cannot recognize or learn faces
frontal lobe Source amnesia : cannot remember how information was acquired

Implicit/Non-declarative memory

Implicit_memory is our internal memory of habits and instinct, in which no complex cognitive processes are necessary.  It is the memory which we use when we offer pre-conditioned responses to stimuli.  Examples of this type include (see also priming)

  • Motor skills:  Learning to associate one stimulus with other stimuli as well as with some inbuilt responses.
  • Perceptual and cognitive skills:  An example of this is the mirror reading test where words which have been reversed in a mirror are read back[EC].
  • Priming phenomena: Here, subjects improve performance on tasks for which they have been subconsciously prepared
  • Perceptual priming: Example of this is when seeing an incomplete sketch helps in identifying the completed sketch later.
  • Conceptual or Semantic priming: Learning the concept of “table” helps in recognizing the concept of “chair”.
  • Non-associative learning (habitation and sensitization) : Response to stimuli changes in the form of augmentation or waning due to repeated stimuli presentation.

The neural correlates of implicit memory have been identified as the amygdala and perhaps the striatum and the cerebellum [KJS].

Now we will examine the Yogic view of memory.

Sri Aurobindo’s view of memory

The traditional term used for human memory in Yoga is Chitta although it is also used to denote the mind as a whole.  This is because Yoga psychology regards mind as all-pervasive with memory as an inherent part of the mind.   The Yogic model of memory is based on the extended model of Man (See Constitution of Man) whereby the individual is not just a physical body with a brain but actually five sheaths of varying density of consciousness.

Sri Aurobindo in his works defined three stores of memory [SA1].

  1. Conscious memory : This refers to organized memory.   It that which can bring up at any moment we like.  It is under our control.
  2. Subliminal memory : It can hold all things, even those which the mind cannot understand, e.g. if you hear somebody talking Hebrew, the subliminal memory can hold that and bring it up accurately in some abnormal state, e.g. the hypnotic. Exact images are retained by the subliminal memory. Mainstream psychology fails to distinguish between the subliminal and the subconscient.  The subliminal consciousness that holds exact memories is far wider and fuller than our waking or surface consciousness, and so cannot be equated with the subconscient.   In layman terms, one can say that the full uninterpreted video of daily events is stored into subliminal memory.
  3. Subconscient memory: This is the memory of impressions, habits and impulses.  It is further divided into mental, vital and physical.   The mental subconscient holds repeated thought patterns, the vital subconscient holds desires and impulses while the physical subsconscient retains the memory of involuntary responses exhibited by our body.  See more on the subconscient

Here is a possible diagram on mind and memory as per Yoga psychology.  For more on this, see Mental Sheath

Buddhi-Manas-Chitta-Ahankara

Buddhi-Manas-Chitta-Ahankara

In his book Synthesis of Yoga, Sri Aurobindo explained the distinction between active and passive parts of Chitta.  The active Chitta described here is the Conscious memory while the passive Chitta corresponds to the Subliminal plus the Subconscient memory

Chitta, the basic consciousness, is largely subconscient; it has, open and hidden, two kinds of action, one passive or receptive, the other active or reactive and formative. As a passive power it receives all impacts, even those of which the mind is unaware or to which it is inattentive, and it stores them in an immense reserve of passive subconscient memory on which the mind as an active memory can draw. But ordinarily the mind draws only what it had observed and understood at the time, – more easily what it had observed well and understood carefully, less easily what it had observed carelessly or ill understood; at the same time there is a power in consciousness to send up to the active mind for use what that mind had not at all observed or attended to or even consciously experienced. This power only acts observably in abnormal conditions, when some part of the subconscious Chitta comes as it were to the surface or when the subliminal being in us appears on the threshold and for a time plays some part in the outer chamber of mentality where the direct intercourse and commerce with the external world takes place and our inner dealings with ourselves develop on the surface. This action of memory is so fundamental to the entire mental action that it is sometimes said, memory is the man. Even in the submental action of the body and life, which is full of this subconscient Chitta, though not under the control of the conscious mind, there is a vital and physical memory. The vital and physical habits are largely formed by this submental memory. For this reason they can be changed to an indefinite extent by a more powerful action of conscious mind and will, when that can be developed and can find means to communicate to the subconscient Chitta the will of the spirit for a new law of vital and physical action. Even, the whole constitution of our life and body may be described as a bundle of habits formed by the past evolution in Nature and held together by the persistent memory of this secret consciousness. For Chitta, the primary stuff of consciousness, is like prana and body universal in Nature, but is subconscient and mechanical in nature of Matter[SA2].

In this passage, the Mother of the Aurobindo Ashram, Mira Alfassa, delineates the working of subliminal memory whose action is far superior to mental or conscious memory.

Outside the mental memory, which is something defective, there are states of consciousness. Each state of consciousness in which one happen to be registers the phenomena of that moment, whatever they may be. If your consciousness remain limpid, wide and strong, you can at any moment whatsoever, by concentrating, call into the active consciousness what you did, thought, saw, observed at any time before; all this you can remember by bringing up in yourself the same state of consciousness. And that, that is never for gotten. You could live a thousand years and you would remember it. Consequently, if you don’t want to forget, it must be your consciousness which remembers and not your mental memory.  Your mental memory will perforce be wiped out, get blurred, and new things will take the place of the old ones. But things of which you are conscious you do not forget. You have only to bring up the same state of consciousness again [MA].

Other Yogic views

Has anyone else in the field of Yoga psychology subdivided the memory(Chitta) in the same way as Sri Aurobindo?   I came across a couple of references; there are possibly more.

K. Ramakrishna Rao [KRR] defined three types of impressions (Samskaras) which are stored in memory (Chitta)

  • Cognition and knowledge (Jnanaja): Memory created by fluctuations of the mind (Chitta-Vritti).
  • Emotional (Klesaja):  Memory of emotions and instincts.
  • Volition and action (Karmaja): memory due to volitional activity.

The second type (emotional) here resembles Sri Aurobindo’s subconscious memory while the first may be related to Sri Aurobindo’s subliminal memory.  The third type is a mystery due to lack of further information.

Sivaya Subramuniyaswami of the Saivite school defines five types of mind [SS]

  • Conscious Mind or Jagrat Chitta:  Ordinary waking mind.
  • Impression Mind or Samskara Chitta: Storehouse of all sensory impressions.
  • Habit Mind or Vasana Chitta: Storehouse of habits and impulses.
  • Superconscious mind or Karana Chitta: Mind of light, all-knowing intelligence.
  • Subsuperconscios mind or Anukarana Chitta: Superconscious mind working through conscious states which brings forth intuition.

Ignoring the last two terms above for now, we can see that the first three terms actually parallel Sri Aurobindo’s taxonomy of memory: Conscious Mind  corresponds to Conscious Memory,  Impression Mind corresponds to Subliminal memory and Habit mind corresponds to Subconscious memory.

Towards a possible correspondence

Neuroscience has identified various types of memory based on empirical research.  Working memory seems to match the characteristics of Conscious Memory (Active Chitta) defined by Sri Aurobindo.  The more theory-specific construct known as short-term memory has been ignored for now.   Implicit neurological memory clearly works with the same instinct as Subconscious memory although some examples (conceptual priming) seem to require greater cognitive activity and might fall in the category of Subliminal memory.   Explicit neurological memory seems to match the action and duration of subliminal memory.  As regards the further neurological classification of explicit memory into semantic and episodic memory, it is unclear and so left alone right now.  In general, detailed neurological experiments may turn up phenomenological classifications which might not always correspond to memory constructs in Yoga psychology.

A rough correspondence seems to be as follows:

Neuroscience Yoga
Sensory Memory Sense-mind or Manas
Working memory Conscious memory or Jagrat Chitta
Long-term implicit memory Subconscious memory or Vasana Chitta
Long-term explicit memory Subliminal memory or Samskara Chitta

Shortlink to this post:http://wp.me/plID6-rI

Blue color link

References

[SN] Neath, I., Surprenant, A.M. Human memory (2nd ed.).Belmont, CA: Wadsworth, 2003, p 171.
[KJS] Kandel, E.R., Schwartz, J.H., Jessel, T.M., Editors, Principles of Neural Science (4th ed.), Oxford, UK: Appleton & Lange, 1991, pp 1227-1245.
[Tul] Tulving, E., Craik, F.I.M. The Oxford handbook of memory Oxford, UK: Oxford University Press, 2000. pp 77-93, 465-501
[AM] O’Keefe, J., Andersen, P., Morris, R., Amaral, D., Bliss, T., Editors, The Hippocampus Book. Oxford, UK: Oxford University Press.  2007, p 592.
[EC] Eichenbaum, H., Cohen N.J. From conditioning to conscious recollection: memory systems of the brain, New York: Oxford University Press.  2001, p.149.  (Google book page link)
[SA1] Sri Aurobindo. Letters on Yoga, SABCL, Volume 22. Pondicherry: Sri Aurobindo Ashram Trust, 1970, pp. 362-3.
[SA2] Sri Aurobindo. Synthesis of Yoga, SABCL, Volume 21. Pondicherry: Sri Aurobindo Ashram Trust, 1970 p. 620.
[KRR] Ramakrishna Rao, K. Consciousness Studies: cross-cultural perspectives. Jefferson, NC and London, UK:  McFarland & Company, Inc.   2002, p. 204.
[SS] Sivaya Subramuniyaswami.  Living with Siva Pocketbook.  Himalayan Academy Publications,  2001. p. 472. (Google book page link)
[MA] The Mother. Collected Works of the Mother, Volume 6. Pondicherry: Sri Aurobindo Ashram Trust, 1979, pp. 20-21.

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20 thoughts on “Similarity between Neurological and Yogic models of human memory

  1. Don Salmon

    Hi Sandeep:

    Another excellent post. There are some profound distinctions between neuroscience, yogic views and those of Sri Aurobindo in particular, that it would be good to keep in mind. I just came across the book “Buddha’s Brain”. The authors are a neurologist and neuropsychologist. They acknowledge their view, in the beginning of the book, that we have a “core” – Buddha Nature, Christ Within, whatever you wish to call it – which is pure, conscious, luminous, loving, etc., very similar to what Mother and Sri Aurobindo call the psychic being, or at least the psychic presence. They also acknowledge that this core within is connected to something “transcendent”. Then they proceed to write the rest of the book without any reference to the core and explain all of our mind and behavior in terms which could almost be written by any believer in purely naturalistic, evolutionary psychology.

    I understand this tactic, and even would agree it’s necessary at the present time, in order to reach many people who would have trouble accepting anything deeper. But the problem is, if you look at even the most trivial facts about memory in light of the deeper Reality, everything changes. We went into this in depth in our book on yoga psychology, but i”ll just give an instance here. In your post on the 4 mental functions (vijnana, ajnana, prajnana and samjnana) you wisely pointed out that their functioning in us can only be truly understood in reference to their original functions at the supramental level. SImilarly, with regard to memory – one might ask, “who” is remembering “what” – if ALL mental functioning is a derivation from the supramental, and if the ‘space’ and ‘time’ within which our memory works is only one space-time continuum within many subtler space-time continuums, then memory is far more complex and subtler than anything current neuroscience can comprehend. As far as the distinction between Sri Aurobindo and other yogic views, to the extent Sri Aurobindo has presented a unique understanding of the supramental consciousness, the understanding of memory (and emotion, will, understanding, and all other mentla/vital/physical functions) will be completely different when seen in the light of the supermind.

    Reply
    1. Sandeep Post author

      Identifying a perfect correspondence is a complex problem for sure because neuroscience works (in detail) from outside-in while Yoga psychology works (generically) from inside-out. It is difficult to one establish a link from the various memory areas in the brain to the mental sheath. This was an attempt to scratch the surface by showing a similarity that struck me.

      Sri Aurobindo’s taxonomy is indeed more complex than I outlined in this article.

      The Superconscient holds innate memory of everything (knowledge by identity).
      There is the earth consciousness which has its own memory (e.g. record of history) which can be accessed.
      Then, we have the Subliminal (mental sheath) and Subconscient (primitive subconscious mind) memories which are a consequence of the individualization of consciousness.
      Furthermore, the psychic being brings its own memories from previous reincarnations.

      And finally we come to the memory held in the brain – working memory – as neuroscience calls it.

      Reply
  2. Sandeep Post author

    A good example of what Sri Aurobindo referred to as subliminal memory can be found in the work of Stephen Wiltshire, an autistic artist, who is able to draw detailed panoramic views of a city purely from memory after taking a helicopter ride over the city.

    See http://www.stephenwiltshire.co.uk/

    Reply
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  8. Sandeep Post author

    Short-Term Memory Is Based On Synchronized Brain Oscillations

    Holding information within one’s memory for a short while is a seemingly simple and everyday task. We use our short-term memory when remembering a new telephone number if there is nothing to write at hand, or to find the beautiful dress inside the store that we were just admiring in the shopping window. …A group of researchers from the Max Planck Institute for Biological Cybernetics in Tübingen, Germany has now come closer to answering this question. They discovered that oscillations between different brain regions are crucial in visually remembering things over a short period of time….

    The scientists observed that, in each of the two brain regions(visual cortex and frontal cortex), brain activity showed strong oscillations in a certain set of frequencies called the theta-band.

    from http://www.sciencedaily.com/releases/2012/01/120131121421.htm

    Reply
    1. Sandeep Post author

      Another result on the same lines

      In-Sync Brain Waves Hold Memory of Objects Just Seen

      Brain waves of many neurons in the two hubs, called the prefrontal cortex and posterior parietal cortex, synchronized to varying degrees — depending on an object’s identity (see picture below). This and other evidence indicated that neurons in these hubs are selective for particular features in the visual field and that synchronization in the circuit carries content-specific information that might contribute to visual working memory.

      The researchers also determined that the parietal cortex was more influential than the prefrontal cortex in driving this process. Previously, many researchers had thought that the firing rate of single neurons in the prefrontal cortex, the brain’s executive, is the major player in working memory.

      http://www.sciencedaily.com/releases/2012/11/121102205139.htm

      Reply
  9. Sandeep Post author

    Use of Light to activate memories in the Brain

    In a new study, published in Nature, a group of researchers from MIT showed for the first time that it is possible to activate a memory on demand, by stimulating only a few neurons with light, using a technique known as optogenetics. Optogenetics is a powerful technology that enables researchers to control genetically modified neurons with a brief pulse of light.

    To artificially turn on a memory, researchers first set out to identify the neurons that are activated when a mouse is making a new memory. To accomplish this, they focused on a part of the brain called the hippocampus, known for its role in learning and memory, especially for discriminating places. Then they inserted a gene that codes for a light-sensitive protein into hippocampal neurons, enabling them to use light to control the neurons.

    With the light-sensitive proteins in place, the researchers gave the mouse a new memory. They put the animal in an environment where it received a mild foot shock, eliciting the normal fear behavior in mice: freezing in place. The mouse learned to associate a particular environment with the shock.

    Next, the researchers attempted to answer the big question: Could they artificially activate the fear memory? They directed light on the hippocampus, activating a portion of the neurons involved in the memory, and the animals showed a clear freezing response. Stimulating the neurons appears to have triggered the entire memory.

    Read more @
    http://www.scientificamerican.com/article.cfm?id=how-to-use-light-to-control-the-brain

    Reply
  10. donsalmon

    Another thing about neuroscience and memory – with Candace Pert’s research and discussion of neuropeptides, it has been acceptable for at least 10 years, within mainstream neuroscience, to speak of memory as not just being lodged in the brain but extended through the body. It is because of this that Dan Siegel is always careful to speak of the “embodied brain” – the brain that exists throughout the body. He has claimed to speak to more than 100,000 mental health professionals, including leading neuroscience researchers, virtually all of whom have accepted his definition of mind as “an embodied and relational process that regulates the flow of energy and information”.

    Reply
  11. donsalmon

    I forgot to add, in regard to the main point, that therefore, one can speak of memories in the body. This used to be a non empirical, New Age-ish term, but with the new solid research, we find it is now acceptable to speak of memories associated with various organ systems. For example, just a decade ago, the memories of heart transplant patients were considered to be impossible (a middle aged white man who had the heart of a deceased, 17 year old African American violinist, a man who never cared for anything but pop music, suddenly acquired a taste for classical violin music – this was due to “memories” associated with the transplanted heart). Now it’s perfectly understandable – there is a complex system of nerves around the heart which makes it legitimate to speak of a “heart brain” – complete with memories and all. In fact, the heart sends more information to the head brain than vice versa. When we talk about “speaking from the heart” – it turns out it is an accurate rather than merely metaphoric way of speaking.

    And in terms of Integral Yoga, it’s interesting to see how much the research on the heart brain is pointing toward qualities that Sri Aurobindo would see as “psychic” – compassion, love, kindness, caring, profound connection and attunement, gratitude, etc.

    Reply
    1. donsalmon

      ah, so interesting how conversations continue a year later:>) I just wanted to add – I’ve been making these parallels for years. In the last few months, I’ve gotten back in contact with a number of people in the Integral Yoga I haven’t spoken to for quite some time. One who is particularly interested in these parallels was concerned that I was making too much of the parallels and not emphasizing enough the differences.

      Good point. There’s a website called “sciy” (or something like that) where often I’ve seen posts marveling at some scientific discovery of the last 50 years and suggesting that “This” was what Sri Aurobindo and Mother were “really” talking about and now that we have these “scientific” (read – “superior”) ways of expressing it, we should just replace those “old fashioned” yogic terms.

      So I thought I’d add – this is just my view – it’s good to keep in mind whenever comparing science and yoga (and not just Integral but, IMHO, any yoga) that science – at least, as practiced almost universally today – covers only an infinitesimal region of existence in comparison with the vast, virtually infinite Reality which yogis are attempting to point us to.

      I know this is out of fashion these days, when so many are so impressed (understandably, at least to our small egos) by the way science can manipulate and control (apparently) the physical world (as a psychologist, i can tell you it’s still pretty minimal what they can do with the mind – fortunately!). And I in NO way mean to denigrate or minimize science – heck, I’m a scientist (or if conducting 2 research projects doesn’t qualify me for that label, than I can say I was at least trained as a scientist, and paid a pretty good penny for that training:>)).

      so yes, by all means, I think it’s fascinating and presumably, helpful to the evolution as well, to see these parallels. But I think it will be, perhaps decades, perhaps even centuries, before science changes enough to really even begin to capture some of the more subtle realities that yoga embraces. (and by then, our notions of space and time will have changed so much we’ll no longer be thinking in terms of linear time or simplistic time measurements like “centuries”!).

      Reply
      1. Sandeep Post author

        Don: There’s a website called “sciy” (or something like that) where often I’ve seen posts marveling at some scientific discovery of the last 50 years and suggesting that “This” was what Sri Aurobindo and Mother were “really” talking about and now that we have these “scientific” (read – “superior”) ways of expressing it, we should just replace those “old fashioned” yogic terms.

        I dont recall reading it there. Maybe you read it in another blog post of mine?

        this one:
        https://auromere.wordpress.com/2012/08/04/predictions-of-sri-aurobindo/

        Reply
        1. donsalmon

          no it was sciy; it’s been a few years – mostly in rich carlson’s posts. sorry i don’t recall exactly where now. I’ve always found your posts to be profoundly respectful of Mother and Sri A, and never took you to be putting science above yogic vision.

          Reply

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