Home | Search Serendip

From Serendip

Neurobiology and Behavior 2000
Class Notes

Jan 18:

Organization of class: to facilitate ongoing conversation, inquiry
  • Student participation: discussion, reading, writing
  • Hear as many voices as possible, share your own
Hmmm. All organizational routine? Wonder if this has anything to do with the subject of the course?
Subject of class: relation between brain and behavior
  • Issue: The Brain is wider than the sky/For put them side by side/The one the other will contain/With Ease - and You - beside ?
  • Assertion: Behavior = brain (nervous system); there is nothing else?
    • Reservations?
    • Significance?

Status of assertion? Truth? If not, what?
  • Science does not deal in Truth, but only in testable hypotheses - "summaries of observations
  • Sample form of relevant observation: previous, current understanding of "possession"/"epilepsy"
  • To explore over semester: what are the relevant observations? are they well summarized by "brain=behavior"? what old questions does assertion help to clarify? what new questions (stimulus for new observations) does it raise?
Hmmm. This is science? Seems like philosophy of science to me. Is it so? Does it matter? Can it possibly be related to the subject of this course?

Jan 20:

The brain and how it works: where to begin?
  • "Brain = nervous system"
    • Brain NOT special, only one part of nervous system
  • Need to start with what one has to begin with
    • KNOWING it will be wrong, figuring out why
    • "every student expected to be wrong three times a week"
  • The stimulus/response box with spaghetti/phone switchboard inside
Alright, at least got one "fact" to keep in mind. Brain is upper end of nervous system, which includes spinal cord, other things. Is he really going to show us its not "special"? As for this "being wrong" thing, is HE going to be willing to be wrong three times a week?
What's wrong with the spaghetti/phone switchboard model? - thinking about crickets
  • Harvard Law of Animal Behavior in female cricket: "under carefully controlled circumstances an animal behaves as it damned well pleases"
    • Could be each time is a different stimulus?
    • Fix model by adding additional stimulus/response connections?
    • Or ... ? Activity-gated divergence?
  • What "stimulus" for male cricket chirping?
    • Could signals start in middle of box?
    • "Choices" be made "inside"?
    • Do crickets "feel like" doing something? Choose? Do people?
    • Needs evidence (new observations), and clearer definition of "input", "output"; to come?
  • Suggests changing from "stimulus/response" to "input/output"
    • See forum for additional suggestion about problems of spaghetti model
Wonder why the Scientific American article doesn't say that female crickets sometimes don't turn?

I THINK I see what he's driving it, but I'm not sure. Is changing from "stimulus/response" to "input/output" REALLY so different? Maybe, if things can REALLY start in the middle ... yeah, it FEELS like they do sometimes. But a cricket? As for the spaghetti model ... who ever really thought that was how the nervous system worked? ... oh, well, maybe .... but is there REALLY a different way of thinking about it here? And is it worth my while to try and figure out what he's talking about?

New "input/output" model has advantages, including both making sense of the observations otherwise clumsy to account for and raising new questions; both, and further elaboration of box model, to be further explored next week

Jan 25:


Jan 27:

Brain=behavior? poll results:


Some further implications of the brain=behavior notion
  • Brains "sort of the same" but sort of different in different people
  • Brains "sort of the same" but sort of different in one person at different times
Interesting. Maybe individuality and "learning" make sense this way? The brain isn't something you're born with that never changes, and its different in every person? But also similar in different people and somehow similar through time in one person? Wonder how that could be?
Elaborating the nervous system as input-output box model
  • The need for processing within the box
    • Why do some people, some times smile for a given input, while other people, other times don't?
  • Maybe there are boxes inside (a "feeling a sense of humor" box?) and what happens for a given input depends on what's going on in each inside box and what they say to one another?
Hmmm. I'm not sure I get this. But .... there is something about this boxes within box idea ... different boxes doing different kinds of processing? ... behavior the result of lots of different smaller processes? ... could be ... maybe it will get clearer as we go along ... I hope.
Finding input-output boxes within the big input-output box
  • "Broken neck" may involve interruption of all connections between brain and spinal cord - two boxes?
    • Spinal cord has inputs and outputs related to body below neck
    • Brain has inputs and outputs related to head
    • There must also be pathways linking the two - brain and spinal cord each both an input and an output for the other
  • Simpler consequences of "broken neck"
    • Inability to move leg when asked
    • Failure to say ouch when leg pinched
    • Both easily understandable in terms of interrupted links between brain, spinal cord
  • Additional phenomena of "broken neck"
    • Leg withdraws when pinched
      • Implies significant capability of spinal cord independent of brain
    • Christopher Reeves doesn't report pain when leg pinched
      • Makes sense in terms of interrupted links
      • But ALSO suggests Christopher Reeves in brain rather than in spinal cord?
    • Christopher Reeves can't "will" leg movement
      • Also makes sense in terms of interrupted links IF one accepts that Christopher Reeves in brain?
Hey, this is kind of interesting. Maybe there ARE smaller boxes within the big box, but I'd also like to know about Christopher Reeves, and quadriplegia. Maybe it would make a web project? Hmmmm, there's something fishy about this "where is Christopher Reeves?" business. I need to think more about this. What does he mean that some things are "easily understandable?", and other things .... Does this all really mean that "I" is a part of neurobiology? .... and maybe only a small part of the nervous system? Grobstein had better be planning to talk more about this.
Thinking of the nervous system in terms of interconnected boxes helps us make sense of the some things, raises some more new and interesting questions. We'll look more into the idea of boxes within boxes next week. If you want to begin getting a sense of what different boxes might be, have a look at Divisions of the nervous system

Feb 1:

Some "brain=behavior" issues from forum:

Looking for more boxes inside the box So that's neuroanatomy? Isn't he going to teach us anything more about this? Where are all the names I need to know? The Nauta Scientific American article, huh? Maybe I should look at that. And maybe at some of the web links. But what about this neocortex thing? Why is he making a big point of that?
Some relevant web references, for Feb 1,3:

Divisions of the nervous system

Brain Development

Brain Variation

Comparative Neuroanatomy (mammalian)

Invertebrate Nervous Systems

Comparative Mammalian Brain Collections

The Whole Brain Atlas

Frog Brain

Neuroscience Tutorial

Leech Neurobiology Newsletter

Global Anatomy, includes neuroscience and histology units, resources


Histology-Nervous Tissue

Types of Nerve Cells

Gallery of Neurons

Feb 3:

Interconnected boxes within boxes within boxes
  • "Its boxes all the way down"
  • The neuron as the smallest box we'll work with
  • Substantial similarities in the neurons in the different larger boxes
    • No special "neocortex" or "spinal cord" neuron
You know, this isn't quite the way I heard about this stuff before. What about what all the stuff about what the bigger boxes DO? How come we skipped over that? You know, I never thought before that in some sense all the bigger boxes are made up of more or less the same smaller boxes. Wonder if that's really true? If so, how can the bigger boxes do different things?
The neuron as an input/output box
  • Soma = cell body
  • Dendritic processes = receiving areas, input
  • Axonal processes = transmitting areas, output
  • Soma small (microns), but processes (particularly axon) can be very long (up to meters)
Some implications of discovering neurons
  • Peripheral nervous system largely axons (though with some ganglia containing cell bodies)
  • rigrous definitions of nervous system "inputs" and "outputs"
    • inputs = sensory neurons, receiving surface outside nervous system
    • output = motor neurons, transmitting surface outside nervous system
Hmmmm. So that's the answer to how we're going to rigorously define inputs and outputs? Might work, but what do we mean by inputs and outputs to the neurons?
Some significant neuron numbers
  • LOTS of neurons (greater than 10 12 in human)
  • Almost ALL (greater than 99.9%) interneurons
    • Both receiving and transmitting areas within nervous system
    • "typical neuron gets input from, sends outputs to 103 other neurons
  • Implications for behavior? Lots going on inside?
This DEFINITELY needs some thinking about. Behavior has to do with the outside world .... somehow all those interneurons must KNOW about the outside world .... hmmm, do neurons "know things"? .... you know, some times what I do seems to have relatively little to do with the outside world .... I wonder ....
Sounds like we need to understand neurons, how they talk to one another, to make sense of any bigger boxes. That's what we'll get to starting next week.

Feb 8:

Some forum thoughts:

Picking up neurons as smallest boxes: Need to understand neurons, signals, inputs/outputs

Finding the "signal" that neurons use - the action potential
  • Evidence from motoneuron axon, muscle, light bulbs
  • External, longitudinal, transient, constant amplitude, moving battery
You know, he's doing it AGAIN. I LEARNED about action potentials already, and there weren't any BATTERIES. Where did these BATTERIES come from? Why can't he just talk about this stuff the NORMAL way, instead of throwing in all these things that confuse me?

This diffusion thing, though, that's kind of interesting. Things always in motion (no "first mover"), random motion gives direction, maybe organization? Have to think more about that.

The resting potential as a way to understand the action potential
  • Light bulb evidence
  • Constant, transmembrane battery
  • Diffusion as a deep physical reality
  • Diffusion of ions down concerntration gradients with differential permeabilities to different ions yields stable battery
  • No significant change in concentration gradient
    • Gradient exists because of independent process - pump
  • Lots of different possible batteries depending on relative permeabilities to different ions
  • Resting potential largely due to high internal potassium and high relative permeability for potassium
Some relevant web references, for Feb 8-17:

Basic Neural Processes

The Virtual Neurophysiology Lab

From Random Motion to Order: Diffusion and Some of its Implications

Feb 10:

From the resting potential to the action potential
  • ionic concerntration gradient, specific membrane permeability - what more?
  • several ionic concentration gradients in addition to potassium
  • different batteries depending on relative permeabilities
  • sodium concentrated outside; inside positive battery with high sodium permeability
  • adjacent membrane regions one with high sodium one with high potassium permeability yields external longitudinal battery!
You know, maybe there IS something to this "battery" idea.

Feb 15:

Some forum thoughts:

Feb 17:

| Course Home Page | Forum | Brain and Behavior | Serendip Home |

Send us your comments at Serendip

© by Serendip 1994- - Last Modified: Friday, 18-Feb-2000 17:28:28 EST