Just spent the last couple of hours listening to Prof. Robert Sapolsky, Stanford University. This was a 11 year old lecture on emergence and I’ve enjoyed every single argument and every single story he said. I can’t believe how lucky we are to have access to this kind of input on the click of a button. Interestingly (and also ironically) enough, he concludes his lecture discussing bottom-up emergent phenomena: people not needing experts or blueprints to tell them how to go about, just randomness and simple rules that in high quantity produce quality. This is around the time first xMOOCs showed up and connectivist theory was taking off. I can’t believe how related the two are.
Tag Archives: neurology
Connectionism
It is the name for the computer modelling approach to information processing based on the design or architecture of the brain. Connectionist computer models are based on how computation occurs in neural networks where neutrons represent the basic information processing structures in the brain.
All connectionist models consist of four parts:
- units: they are what neutrons are to the biological neural network, the basic information processing structures. Most connectionist models are computer simulations run on digital computers. Units in such models are virtual objects and are usually represented by circles. A unit receives input, it computes an output signal and then it sends the output to other units. This is called activation value. The purpose of the unit is to compute an output activation.
- connections: connectionist models are organised in layers of units, usually three (3). A network however, is not simply an interconnected group of objects but an interconnected group of objects that exchange information with one another. Network connections are conduits. The conduits through which information flows from one member of the network to the next are called synapses or connections and are represented with lines. (in biology synapses are the gaps between neutrons, the fluid-filled space through which chemical messengers -neurotransmitters- leave one neutron and enter another)
- activations: activation value in connectionist models are analogous to a neuron’s firing rate or how actively it is sending signals to other neurons. There is a big variability between the least active and the most active neutrons expressed in a scale fro 0 to 1
- connection weights: The input activations to a unit are not the only values it needs to know before it can compute its output activation. It also needs to know how strongly or weakly an input activation should affect its behaviour. The strength or weakness of a connection is measured by a connection weight. They range between -1 to 1. Inhibitory connection reduce a neuron’s level of activity; excitatory connections increase it.
Yet, the behaviour of a unit is never determined by an input signal sent via a single connection, however strong or weak that connection might be. It depends on its combined input. That is the sum of each input activation multiplied by its connection weight. The output activation of a unit represents how active it is, not the strength of its signal.
Connectionist networks consist of units and connections between units and have some very interesting features like emergence of behaviour. This does not reduce to any particular unit (liquidity in water). Graceful Degradation and Pattern Completion are two ways in which activations are spread through a network. They are not classical computers, their behaviour does not arise from an algorithm, they learn to behave the way they do.
References
Robert Stufflebeam, 2006. Connectionism: An Introduction (pages 1-3), in CCSI (Consortium on Cognitive Science Instruction) supported by the Mind Project, full article available here
Image available here
Connectomics
Connectomics uses advanced brain imaging techniques to identify and map the intricate web of white matter (communication lines) that link gray matter (neural brain volume). Mapping such networks occurs at the level of synaptic connections. This research began in the 70’s but has recently gained interest thanks to technical and computational advances that automate the collection of electron-microscopy data and offer the possibility of mapping even large mammalian brains. “Connectome” was coined in analogy with the “genome”—the entirety of an organism’s hereditary information—studied by biologists. To imagine how the story of the connectome will unfold over the next few decades, it’s helpful to recall the history of the genome. Connectomics is more challenging than genomics; the structure of the brain is extraordinarily complex. With an electron microscope, the branches of neurons can be seen clearly, even when they are tightly packed together in the brain.
People with high creative capacity have more connections between their left and their right hemispheres of their cerebral cortex.
References
Seven Sins of Memory (2003)
Our self is based on memories of past experiences while the retrieval, recollection and reconstruction of the past is reciprocally influenced by the self. Memory’s imperfection is classified in this book in seven sins (intended here as in transgressions fatal to spiritual progress/ ways in which the normal, everyday operations of our mind may occasionally produce suboptimal or flawed memory experiences):
- Forgetting: 01 transience/ 02 absent-mindedness/ 03 blocking
- Distortion: 01 misattribution/ 02 suggestibility/ 03 bias
- Intrusive memories: 01 persistence
See also; Joseph LeDoux, 2002, Synptic Self: In the absence of learning and memory processes the self would be an impoverished expression of our genetic constitution
Internet as a memory source
An interesting research is conducted by B. Sparrow, J. Liu and D.M. Wegner in 2011 and presented in ‘Google Effects on Memory: Cognitive Consequences of Having Information at Our Fingertips’. Their experiments focus on whether online access to search engines has become a primary transactive* memory source. They have conducted four experiments proving that:
01. when we are faced with a gap in our knowledge, we are primed to turn to the computer to rectify the situation (…) 02. when people don’t believe that they will need information for a later exam, they do not recall it at the same rate as when they do believe they will need it (…) 03. believing that one won’t have access to the information in the future enhances memory for the information itself, whereas believing the information was saved externally enhances memory for the fact that the information could be accessed at lest in general (…) 04. people don’t remember “where” when they know “what”but do remember where to find the information when they don’t recall it (…) people expect information to remain continuously available.
The results of the study suggest that processes of human memory are adapting to the advent of new computing and communication technology. In ” The Internet as a Memory Source: How the Brain is Keeping Up” the author uses this information to focus to the neurological/biological implications of this development. Is the existence of internet and its use as an external memory source changing the way our brains form synapses? For it seems that we no longer store information in the long term memory but rather its location.
Sparrow et al. use an interesting phrase: “we are becoming”, they say, “symbiotic with our computer tools, growing into interconnected systems”. It’s almost as if remembering through these systems is not any different that sharing memories with other individuals, plus through internet we have access to a vast range of information at any point.
*TRANSACTIVE memory: a combination of memory stores held directly by individuals and the memory stores they can access because they know someone who knows that information.
Image available here.
Neuroplasticity
Neuroplasticity: The brain’s natural ability to form new connections in order to make up for for injury or changes in the environment. The ability of the brain to reorganize pathways between neurons as a result of new experiences. (definition extracted from Stanford Webpage)
Image showing the neural connections in the brain of a newborn, a 3 month old, a 15 month old and a two year old child.
The hippocampus is at the front of the brain and was examined in Magnetic Resonance Imaging (MRI) scans on 16 London cabbies. The tests found the only area of the taxi drivers’ brains that was different from the 50 other “control” subjects was the left and right hippocampus (…) The posterior hippocampus was also more developed in taxi drivers who had been in the career for 40 years than in those who had been driving for a shorter period (…) “This is very interesting because we now see there can be structural changes in healthy human brains.”
BBC News World edition, Taxi drivers’ brains ‘grow’ on the job, Tuesday, 14 March, 2000, full article available here
A cab driver’s hippocampus — the part of the brain that holds spatial representation capacity — is measurably larger than that of a bus driver. By driving the same route every day, the bus drivers don’t need to exercise this part of the brain as much. The cabbies, on the other hand, rely on it constantly for navigation. If you were to restrict certain senses — like vision, for instance — your brain would make a similar adaptation. This great survival machine will rewire itself, opening neuro pathways to heighten the power of other senses to keep you from falling off a cliff or get eaten by a tiger.
Daniel Honan, Neuroplasticity: You Can Teach An Old Brain New Tricks, Big Think, full article available here
Neuroplasticity is what allows us to take our experiences, then learn from them and form new memories. Huge changes are occurring in the brain during these early stages of cognitive development, but the truth is that our neural networks continue to build on each other until the day we die (…) The more often neural pathways fire, the stronger the connections will become. This is called long-term potentiation, and it is the basis of all learning and memory formation (…) The big implication here is that if our brain changes itself based on our experiences, then by changing our experiences we can actively reshape our brains
Educational Research, Cognitive Science & Neuroscience
Notes from MIT’s Online Education Policy Initiative Report, Pages 6-10
ER: Constructivism: Dewey, experiential learning, Piaget, Vygotsky, Montessori, inquiry and discovery. Active learning, teaching laboratories, Amos Eaton (1824), active instruction, Mazur, peer learning, all-hands-on courses, mini-lectures, simulations experiments. Online counterparts are flipped classroom. Project -based learning, video disks, personal computers and calculators. Papert’s Constructionism, a refinement of constructivism, development of Lego Mindstorms, robot design, prototyping technologies. Problem-based learning, imprecisely defined problems, self-directed learning peer learning, teamwork, internships, work-study programs, blurred boundaries between college and workplace. Student-centered education, reflection, discussion, interdisciplinary thinking, self-paced learning, Bloom, students in small cohorts. Online counterparts are Peer2Peer University where peer is the primary instructor.
CS: level of the brain, Ebbinghaus, how memories form and persist, mind wandering, task-unrelated thoughts, make students curious, retrieval practice, engaging repeatedly in recall activities
is called interpolated testing, block of practice right after students have learned a topic, contrast between storage strength and retrieval strength, concept of desirable
difficulties,generation effect, generation of answers can help learning even if they are wrong, and feedback is effective even if it is corrective. Cognitive load theory, “compression” of new information, novices should be given worked examples
rather than open-ended problems. Impact of context, the context of the learning reflect the context in which that information will likely be used.
N: level of the neurons, initial encoding, integration of memories, consolidation, synaptic and system levels, sleep, blocked learning may be associated with saturation at the synapse during a process known as long-term potentiation, cognitive load has been shown to be measurable using pupillary dilation, activation of sensorimotor brain regions would enhance understanding of torque and angular momentum, MRI shows more active training
methods correlated not only with better test performance but also with greater stimulation of the predicted brain regions
Image available here
How does creativity work?
Besides focus and concentration, two other abilities are involved:
Defocused attention: the tendency to not focus excusively on the relevant aspects of a situation, but notice also seemingly irrelevant aspects. It is only when one does not yet know what are the relevant dimensions—or when those assumed to be relevant turn out not to be—that defocused attention is of use.
- High sensitivity even to subliminal impressions; stimuli that are perceived but of which one is not conscious of having perceived
- Risk talking
- Tolerance of ambiguity & delayed gratification
- leaning toward non conformity and unconventionality
Flat associative hierarchies: the steepness of one’s associative hierarchy is measured by comparing the words generated in response to stimulus words (those who generate many have flat associative hierarchy)
Thinking modes: thought varies in a continuum between these two extremes. This capacity to shift between analytic and associative thought is sometimes referred to as contextual focus.
- Associative thought is contrasted with a rule-based, convergent, or analytic mode of thought that is conducive to analyzing relationships of cause and effect between items already believed to be related. In associative thought one considers items in detail or considers multiple items at once, which facilitates detecting likenesses and integrating them
- Analytic thought is believed to be related to what Freud termed ‘secondary process’ material. In analytic thought one considers items in a compact or ‘atomic’ form which facilitates mental operations on them.
Gabora, L. (2010). Revenge of the ‘neurds’: Characterizing creative thought in terms of
the structure and dynamics of human memory. Creativity Research Journal, 22(1), 1-13.
Image: http://www.zmescience.com/science/neurology-science/neuron-database-06042015/
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Matters of Memory_Kandel’s “In search of Memory” Part A
Matters of memory and learning are at the epicentre of Kandel’s research. In bis book, “In Search of Memory ” he describes his experiments with Aplysia. In fact, it was through the experiments with Aplysia that led Kandel to realize that the number of synapses in the brain is not fixed -it changes with learning!
Consistent with the one-process theory, the same site can give rise to both short-term and long-term memory in habituation and sensitization. Moreover, in each case a change in synaptic strength occurs. But consistent with the two-process theory, the mechanisms of short- and long-term change are fundamentally different. Short-term memory produces a change in the function of the synapse, strengthening or weakening preexisting connections; long-term memory requires anatomical changes. Repeated sensitization training (practice) causes neurons to grow new terminals, giving rise to long-term memory, whereas habituation causes neurons to retract existing terminals. Thus, by producing profound structural changes, learning can make inactive synapses active or active synapses inactive. (page 126)
Kandel, E. R., 2006, In Search of Memory: The Emergence of a New Science of Mind, Book available here
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Matters of Memory_Eric Kadel and CPEB3 Prions
(Credit: Lab of David Sulzer, PhD, Columbia University Medical Center)
The authors argue that the long term mice memories are preserved with Prions (protein infectious particles). Although regular prions cause damage to the cells there is a type of prions identified in mice as CPEB3 that work inside the neurons to maintain long-term memories.
Prion aggregates renew themselves by continually recruiting newly made soluble prions into the aggregates. “This ongoing maintenance is crucial,” said Dr. Kandel. “It’s how you remember, for example, your first love for the rest of your life.”
This discovery, states Kandel in his “In Search of Memory”, raised the intriguing possibility—so far only that—that spatial maps may become fixed when an animal’s attention triggers the release of dopamine in the hippocampus and that dopamine initiates a selfperpetuating state also mediated by CPEB.
THE IMPORTANCE OF ATTENTION IN STABILIZING THE SPATIAL MAP raises another question: Is the spatial map, a map formed by learning, similar in all of us? Specifically, do men and women use the same strategies to find their way around an environment? (…) Gender differences in forming the spatial map take on additional significance when considered in a broader context: To what degree do men’s and women’s brain structures and cognitive styles differ? Are those differences innate, or do they stem from learning and socialization?
References
Long-term Memories Are Maintained by Prion-like Proteins, Article Published in July 2, 2015, Full article available here
Kandel, E. R., 2006, In Search of Memory: The Emergence of a New Science of Mind, Book available here
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The empty brain by Robert Epstein
Article in AEON by Robert Epstein on why our brains should resist the IP metaphor.
https://aeon.co/essays/your-brain-does-not-process-information-and-it-is-not-a-computer
In Liane Gabora’s “Regenge of the Neurds” the same argument is being made:
In a computer memory each possible input is stored in a unique address. Retrieval is thus a matter of looking at the address in the address register and fetching the item at the specified location. Since there is no overlap of representations, there is no means of creatively forging new associations based on newly perceived similarities.
References
Gabora, L., 2010, ‘Revenge of the ‘neurds’: Characterizing creative thought in terms of
the structure and dynamics of human memory’. Creativity Research Journal, 22(1), 1-13.
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
connecting data to information to knowledge 