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Posts tagged with brain

A plant that turns toward the light, or a worm that writhes after severation, doesn’t do so out of free will.Their internal biochemistry mechanically responds in a deterministic (if stochastic) way. They don’t make choices.
In Vehicles, Valentino Braitenberg asks if we humans aren’t the same way.
 
Even I could come up with the easy arguments for stimulus→response:
something annoys me → bad mood → don’t pay attention to the car that’s pulling out → accident
physics says so
I read a compelling book about robots → inspired to go to graduate school and dedicate my life to synthetic consciousness → entrenched in a career with no prospects
people predictably respond to stimuli: we avoid people & situations we don’t like and gravitate to what we do like (subject to feasibility constraints).
 
But Braitenberg does something much more convincing. He builds robots to prove his point.
He starts by resolving the problem of Burridan’s Ass stochastically. A phototropic robot might be stuck at θ = 0° between two light sources, but since we can’t get it to exactly 0° the robot—without free will or choice—heads toward one of the “bales of hay”.

What seemed like a paradox according to pure thought went away when someone took the paradox seriously enough to build a physical model. 
That problem is resolved with two wires connecting two stimuli to two engines. As the book progresses Braitenberg builds more lifelike robots using more connections—complex networks that reroute external stimuli to mechanistic, deterministic robotic response.

Braitenberg doesn’t get all the way to the dramatic complexity of "I love you! … I know." but given what’s possible with a few tens of connections, what could be possible with hundreds of trillions of connections?

Because of this book I went through years of my life believing I was probably an automaton.

A plant that turns toward the light, or a worm that writhes after severation, doesn’t do so out of free will.
image
Their internal biochemistry mechanically responds in a deterministic (if stochastic) way. They don’t make choices.

In Vehicles, Valentino Braitenberg asks if we humans aren’t the same way.

 

Even I could come up with the easy arguments for stimulus→response:

  • something annoys me → bad mood → don’t pay attention to the car that’s pulling out → accident
  • physics says so
  • I read a compelling book about robots → inspired to go to graduate school and dedicate my life to synthetic consciousness → entrenched in a career with no prospects
  • people predictably respond to stimuli: we avoid people & situations we don’t like and gravitate to what we do like (subject to feasibility constraints).
 

But Braitenberg does something much more convincing. He builds robots to prove his point.

He starts by resolving the problem of Burridan’s Ass stochastically. A phototropic robot might be stuck at θ = between two light sources, but since we can’t get it to exactly the robot—without free will or choice—heads toward one of the “bales of hay”.

image

What seemed like a paradox according to pure thought went away when someone took the paradox seriously enough to build a physical model

That problem is resolved with two wires connecting two stimuli to two engines. As the book progresses Braitenberg builds more lifelike robots using more connections—complex networks that reroute external stimuli to mechanistic, deterministic robotic response.

image

Braitenberg doesn’t get all the way to the dramatic complexity of "I love you! … I know." but given what’s possible with a few tens of connections, what could be possible with hundreds of trillions of connections?

image

Because of this book I went through years of my life believing I was probably an automaton.


hi-res




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Discussing the first year of life.

  • In-born aptitudes include
    • theory of other peoples’ minds (looking at where they’re looking, show surprise when they know something they “shouldn’t”) (this gives some idea of what autistic people go through—they lack a skill that one-year-olds have!)
    • animate versus inanimate things—causality, essentially

Infants do reason. They just have less knowledge than adults.

Brain hemispheres act the same at birth but begin to specialise over time. (So could there be an alien environment where human babies would specialise their brains along different lines?)

There’s no one thing that makes the human brain superior to other animals’ brains (at least not that we’ve found). It’s thought to be the interaction of various factors—as well as our long developmental period—that make us able to build rocket ships, paint potato eaters, invent radio and discuss these things on it.

image

(Source: BBC)




Neurons are designed with a lot of listeners (the dendrite) and just one talker (the axon terminal).
If we consider the brain as a robust piece of hardware, which can
learn across environments,
operate independently of the rest of the organisation of the superstructure,
and function even after sustaining physical damage,
maybe there’s a universal principle of good design here.

Neurons are designed with a lot of listeners (the dendrite) and just one talker (the axon terminal).

If we consider the brain as a robust piece of hardware, which can

  • learn across environments,
  • operate independently of the rest of the organisation of the superstructure,
  • and function even after sustaining physical damage,

maybe there’s a universal principle of good design here.


hi-res




199 Plays • Download

The Nervous System

  • dissections of live criminals’ brains
  • animal spirits (psychic)
  • neuron νεῦρον is Greek for cord
  • Galen thought the body was networked together by three systems: arteries, veins, and nerves
  • Descartes as the source of the theory of reflexive responses—fire stings hand, νευρώνες tugging on the brain, fluids in the brain tug on some other νευρώνες, and the hand pulls away—automatically.
  • the analogy of a clock (…today we’re much smarter. We think of brains as being like computers, which is definitely not an outgrowth of today’s hot technology!)
  • cogito ergo sumsensation is what’s distinctive about our brains. How could a clock feel something? (Today again, we’re much smarter: we think it’s the ability to reflect on thought—anything with at least one “meta” term in it must be intelligent.)
  • Muscles fire like bombs exploding (a chemical reaction of two mutually combustible elements)—and the fellow who came up with this theory had been spending a lot of time in the battlefield where bombs were the new technology.
  • autonomic, peripheral, central nervous systems
  • Willis, Harvey, Newton
  • What makes nerves transmit information so fast?
  • Galvani’s theory that electricity is only an organic phenomenon. (Hucksters arise!)
  • The theory of the synapse—it’s the connections that matter.
  • The discovery that nerves aren’t continuous connected strings, but rather made up of billions of individual parts.
  • Activation thresholds—a classic and simple non-linear function!

(Source: BBC)




Robert Sapolsky on the Limbic System (por StanfordUniversity)

  • olfactory bulb takes up 40% of a rodent brain’s projections
  • rhine encephalon — originally viewed as to do with olfaction in all species
  • gathers whatever sense-data pertains to emotions
  • Paul McLean’s triune brain (phylogenetic conservation): hypothalamuspituitarybrainstemmidbrain⊕thyroid⊕pancreas⊕heart (robotic, boring—until it goes wrong) + the limbic system (mostly a mammalian invention: birds, reptiles, fish have less complex limbic systems) ⊕ emotional complexity + cortex (gleaming analytical machine of cognitive expertise — greatly expanded in vertebrates, in mammals, in primates, in us — cortex tied to limbic system, not independent)
  • decisions made under duress
  • think about your own mortality (kicking out “CRH”)
  • so limbic influences cortex and vice versa
  • we are “a fancy species”
  • Odene’s curse — lose the capacity for automatic breathing (you die of sleep deprivation)
  • Antonio DiMasio, Descartes’ Error
  • James Pabes
  • the limbic regions compete to control the hypothalamus (they can shush each other up)
  • edge/network/synaptic distance to the hypothalamus
  • every sense has to go through ge;3 synapses to tell the limbic system anything—except olfaction can hop 1.
  • olfaction takes up only 5% of our brain
  • grey matter (nuclei) vs white matter (axon cables wrapped in myelin)
  • amygdala, hippocampus, septum, mammilary bodies, hypothalamus, thalamus, prefrontal cortex
  • frontal cortex: where am I being touched? which note are you playing? how do I do long division? which limb do I want to move? plus long-term planning, gratification postponement, emotional regulation, impulse control
  • frontal cortex is most recently evolved, relatively largest in humans, not fully mylenated until age 25;size of prefrontal cortex in primates grows as size of typical social group
  • amygdala tells you to be afraid and pings the hippocampus: “Hey, remember to be afraid of this in future”




Birds appear to offer, in their behavior, neurophysiology, and neuroanatomy a striking case of parallel evolution of consciousness. Evidence of near human-like levels of consciousness has been most dramatically observed in African grey parrots. Mammalian and avian emotional networks and cognitive microcircuitries appear to be far more homologous than previously thought. Moreover, certain species of birds have been found to exhibit neural sleep patterns similar to those of mammals, including REM sleep and, as was demonstrated in zebra finches, neurophysiological patterns, previously thought to require a mammalian neocortex. Magpies in particular have been shown to exhibit striking similarities to humans, great apes, dolphins, and elephants in studies of mirror self-recognition.

Evidence that human and non-human animal emotional feelings arise from homologous subcortical brain networks provide compelling evidence for evolutionarily shared primal affective qualia.

“The absence of a neocortex does not appear to preclude an organism from experiencing affective states. Convergent evidence indicates that non-human animals have the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states along with the capacity to exhibit intentional behaviors. Consequently, the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness. Non-human animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological substrates.”

the Cambridge Declaration on Consciousness, 2012

hat tip to fibrations

(Source: fcmconference.org)




from “On Self-Referential Sentences” by Douglas Hofstadter, originally in Scientific American (January 1981), reprinted in Metamagical Themas (1985)
via crystilogic




Brains sound like a wicked-hard space to think about.
It’s a tightly connected (but not totally connected) network (graph theory)
Each of the nodes’ 3-D location may be important as well (voxels)
The signals propagate through time (dynamical)

Brains sound like a wicked-hard space to think about.

  • It’s a tightly connected (but not totally connected) network (graph theory)
  • Each of the nodes’ 3-D location may be important as well (voxels)
  • The signals propagate through time (dynamical)

hi-res




  • rats’ brains, and presumably ours, tessellate the plane surface we walk on with multiple overlapping triangular grids
  • (is there a mathematical reason triangles are optimal? euler characteristic, perhaps?)
  • path" neurons in the hippocampus fire as we cross these grids to reconstruct our previous paths
  • boundary" neurons in the hippocampus fire as we approach the boundaries of a space
  • (what about agoramaniacs? or ancient people who hunted buffalo on the plain?)




Rat hippocampus, photographed by Thomas Deerinck. via billydalto


Rat hippocampus, photographed by Thomas Deerinck. via billydalto


hi-res