BSIE 2010: Session 9

Brain, Science, and Inquiry-Based Education K-12 Summer Institute 2010

 

  Session 9

Picking up  from yesterday

we should be just as concerned about the student who is fixated on monopolizing the conversation or discussion, similar to way we are concerned about that student who appears to be fixated on making no comment at all.  The "talker" may not be open about, or aware as to why he has the need to dominate, while the non-talker may not be aware of just what is needed to make him feel more as an active talking participant within the group.  Changes are needed by both ... Mattie

People will move out of their comfort zone when they feel valued ... Geneva

The topic of students who were unwilling to conversate was brought up ... I thought it was interesting how Paul described this as  ... they are being inhibited by something.I feel forming relationships with my students is very important. Walls come down ... Ashley

these molecules did not get in the order nor were they placed in this order, rather the order was an accident of trying different possibilities. The arrangement we see now is the one that worked. We don't know how many different variations existed that did not survive ... Susan

Social ideas, stereotypes, norms, and values are culturally constructed.  This being the case, I feel that it is extremely interesting to consider the implications for learning and information gathering ... Keith

 

The brain: bringing the threads together

Conversation: valuable sharing of differences to create, individually and collectively, new explanations/stories/constructions (looping)

Science/empirical inquiry: valuable testing of expectations based on summaries of observations/explanations/stories with observations to create, individually and collectively, new explanations/stories/constructions (looping)

Evolution: exploration of possibilities driven by randomness (trying new things out) and influenced by what works at any given time;  trying things out together with interaction/conversation (looping) itself creates new possibilities/constructions

The brain as a constructor?  Using randomness, trying things out to see what works?   Having/sharing differences to create new possibilities/constructions?  Working individually and collectively?  Always exploring unless inhibited?  Where do thoughts one doesn't think one has come from? 

Contra Descartes, not a brain and a mind but ... a brain

• Emily Dickinson (1830-1886)
• Francis Crick, 1995: The Astonishing Hypothesis: "a person's mental activities are entirely due to the behavior of nerve cells ... and the atoms, ions, and molecules that make them up and influence them".
• V.S.Ramachandran, 2003: " it never ceases to amaze me that all the richness of our mental life - all our feelings, our emotions, our thoughts, our ambitions, our love life, our religious sentiments and even what each of us regards as his own intimate private self - is simply the activity of these little specks of jelly in your head, in your brain. There is nothing else"
• Paul Grobstein, contemporary: "Brain = behavior, there isn't anything else."

• Behavior can be altered by altering the nervous system
  • Traumatic brain damage
  • Surgery, drugs, and ... ?
  • Epilepsy as an instance
• Lots of aspects have behavior, even quite sophisticated ones, have "material" feel about them
• Surprising and quite sophisticated things can emerge from interactions of simple elements (of which the brain/nervous system is an example, as we'll see).
  • one example
  • another
  • and another
• It isn't that anything "disappears" as one discovers things related to the brain but rather that the Brain gets "wider"
  • Disadvantages?
    • Vulnerability?
    • Amorality?
    • Indifference to the interpersonal?
    • Using MRI's to See Politics on the Brain ???
  • Advantages:
    • we can ourselves create new understandings of the world, individually and collectively
    • would make the unobservable (the unconscious) observable?

The "real" nervous system - different if behavior different?

• Among different kinds of organisms?
  • Notice neocortex present in some, not all vertebrates
• Among different individuals? within individuals over time? - New imaging techniques
  • Notice that differences leave open the question of what causes differences (genes, experiences, activity, culture, etc)
  • Implies that "information" can alter matter; not mysterious, "info" turns out to be perturbations of matter organization in neurons, can via metabolic processes influence organization/properties of neurons
• Why the diversity?  Is there a "best" nervous system or .... ?

The brain itself as an explorer/creator

 

The sphaghetti (switchboard, "reflex") box model Virtues Box Input/output relations Historical opening to "rigor" Problems (if "brain=behavior") stereotopy nodes as relays - why need them? ?

Problems of reflex model

Harvard Law of Animal Behavior

"Under carefully controlled experimental circumstances, an animal will behave as it damned well pleases"

Divergence and convergence

 

Sphaghetti (switchboard, "reflex") plus box model Virtues Box Input/output relations Nodes as integrators rather than relays Problems (if "brain=behavior") more variation, but still stereotopy "stimulus", "response" starting to look a little less clear ?

A rethinking - boxes in boxes

 

The sphaghetti (switchboard, "reflex") box model Virtues Input/output box Parts sort of like whole, themselves input/output boxes, follow similar rules? Problems (if "brain=behavior") stereotypy, still "stimulus" dependent poor definition of "stimulus", "response" ? Issues: Is the nervous system a "box"? boundaries? Does it have boxes inside it? How do boxes "integrate"? What's inside THOSE boxes? (boxes all the way down?)

Facing up to the stereotopy, stimulus-response problem ... freeing the box from the outside world, adding autonomy

 

The boxes inside boxes (with "autonomy") model Virtues Input/output box made up of input/output boxes Gets rid of "stimulus", "response", replaces with "input", "output"   Stimulus (input) = something happening OUTSIDE the nervous system   Fixes stereotopy problems, permits "autonomy"   Nervous system may be active, change its activity, even in the absence of changing inputs Stop thinking of nervous system as stimulus/response device   Problems (if "brain=behavior")

Diversity from combination/organization/interaction/conversation - every brain a unique exploration of possibilities

The "real" nervous system - an input/output box consisting of interconnected input/output boxes?

 

	photo from Kemali and Braitenberg, Atlas of the Frog Brain, Springer-Verlag, 1969

Caudal to rostral sequence of "boxes" of "central nervous system" originates in neural tube development, is commmon to all vertebrates

(will defer to later discussion of invertebrates, variations among vertebrates)

Each box in turn (somewhat arbitrarily) subdividable into smaller boxes (with some differences among vertebrates, to return to)

And those ... yes, "its boxes all the way down"

• dorsal medulla, cerebellum
• ventral medulla
• forebrain
• spinal cord

The smallest box: neurons everywhere

Invertebrate nervous systems also have neurons, but differently arranged - makes sense?

Neuron as common, smallest box and as input/output element, connected to other boxes

• Cells, like other cells, but specialized to receive/process transmit "information" (as opposed to matter or energy)
• Size scale - tens of microns (10-6) meters)
• Larger boxes must differ in how smallest interconnected
• Relevance of numbers? enough to "account for all the uniqueness that exists among people"? ... 1012exp1012 possible nervous systems?
• Differences between people, differences between organisms due to .... not building blocks but assembly (architecture)
• Need to know how neurons work - to return to

Can use boxes->boxes ... ->boxes(neurons) to show that larger boxes interconnected, in relatively specific ways (anatomical specificity) and to rigorously specify "input" and "outputs" of largest box ... nervous system itself

• grey matter (soma, dendrites, pre-synaptic terminals, neuropil) vs white matter (bundles of axons, tracts)
• central vs peripheral nervous system (some ganglia, but largely axon bundles
• output elements of nervous system (motoneurons, plus) = neurons with axon terminating outside nervous system
• input elements of nervous system (sensory neurons, plus) = neurons with receiving surface (dendrites) outside of nervous system
• everything else = interneurons
• numbers/proportions: more reason to think of ns as "semi-autonomous"

So ... at least parts of our box within box model real ... and helps define "input" and "output" more rigorously

Implies: different regions on brain, different brains, different behaviors largely because of different assemblies of similar elements ("architecture")

 

Topographic organization - anatomical specificity (input and output locations)

Outputs - (myotomes)

• Motoneurons located at levels of neuraxis related to location of muscles controlled
  • spinal AND cranial motor nuclei/nerves
• Each motoneuron activates only one muscle
• Implications:
  • "action" is not one output but pattern of activity across lots of them - "motor symphony"
  • source of lots of additional variation in behavior
  • lots of outputs/nervous system involved in any "action", is "distributed" characteristic
  • need to understand how patterns of activity created, parts coordinated

Inputs -  (dermatomes)

• Sensory neurons terminate at levels of neuraxis related to location of receptors
  • spinal AND cranial ganglia/nerves/terminal zones
• Implications
  • "sensation"/"perception" not one input but pattern of activity across lots of them (across modalities and, as will be seen, in one modality - another "distributed" characteristic
  • need to understand how inputs combined
  • thought = pattern of activity across lots of neurons

For additional information: central nervous system - regional neuroanatomy peripheral nervous system overview Sympathetic/parasymaphetic systems Enteric nervous system cranial nerves/sensory ganglia/motor nuclei spinal nerves/sensory ganglia/motor nuclei

 

 

Brain a distributed system, works by interaction/conversation among boxes

 

Usefulness of the interconnected box model and ... another box?

• Capabilities of spinal cord
• Quadriplegia (slightly better) - relevance of topographic organization
  • Christopher Reeves and ... , from NIH
• The "I-function"

 

Observations "surprising", but have to be accepted - Issue is "how to make sense of them"

Two kinds of behavior ("reflex" versus something-else) intuition probably not useful

• Spinal cord capable of very sophisticated activity
• Brain capable of quite unsophisticated activity
• Distinction between "reflex" and other things?

Break problem down into components, see what actually difficult/suprising (good general principle in science)

 

• "foot withdraws when irritated" - spinal cord capable of sophisticated activity on own
  • is ok ... given topography and "physical contiguity principle ("PCP")

• "person doesn't say ouch when foot irritated" - behavior frequently depends on linking paths within nervous system
  • is ok ... given topography and "physical contiguity principle ("PCP")

• "person doesn't move foot when hearing (or reading) request to do so" - behavior frequently depends on linking paths within nervous system
  • is ok ... given topography and "physical contiguity principle ("PCP")

• "person says foot irritation not felt/experienced" - behavior frequently depends on linking paths within nervous system
  • is ok ... given topography and "physical contiguity principle ("PCP") AND ..
  • "behavior" can occur without it being experienced by the behaving organism AND ...
  • neuronal circuitry adequate to support "feeling/experiencing" (I-function) is in the brain (spinal cord not needed for this function)

   

• Where is Christopher Reeves? Is he paralyzed? Does he feel pain? - has to do with "mind", "self", "soul", "personality", "consciousness" ?
  • words requiring redefinition in light of new experiences/observations?

 

Ascending somatosensory pathways Descending motor pathways   Action (and perception) as problems of patterns of activity (thinking?) Behavior as dependent on internal communication among boxes I-function as a distinct box I-function is not necessary for behavior dependent on other boxes for access to input and influence on output necessary/helpful in thinking about meanings of "paralysis", "pain"?, "choice"?

The bipartite brain