#+TITLE:Cognitive and Comp Neuroscience
#+OPTIONS: num:nil ^:nil toc:3
#+STARTUP: hideblocks
* Meta
Assignments
1. 100-word summary after every class on either/any of the presenters
2. 10 or so page research paper due at the end of the semester
covering a topic related to the content of the course, include a
bibliography, email either Prof. with any questions
Weekly Reading
- ListServe with reading material before classes, go to
http://mail.cs.unm.edu and sign up for =comp-cog-neurosci=
- file:data/calendar-of-speakers.pdf
* Notes
** 2011-01-19 Wed -- Introduction to the class
The content of this course will start with the philosophy of mind and
end with sociology
** 2011-01-26 Wed -- Phil o Mind and AI intro
*** philosophy and cognitive science /constrain/ each other
Three historical views of consciousness
- self-consciousness :: John Locke, self-reflection, continuity of
identity, our most primary sensations are those "from the inside"
- phenomenal experience :: Thomas Nagel, there is something that it is
/like/ to be that organism -- qualia
- phenomenalogical foundation :: Edmund Husserl -- "the reflective
study of the essence of consciousness as experienced from the
first-person point of view" -- extends beyond qualia to meaning
and intentionality
Features
- perspectival -- from a first person perspective
- immediacy
- privileged
(Descarts) Dualism -- matter and consciousness are /different kinds/
with different properties. Matter /res extensa/ has size and shape
and the mind /res cogitans/ doesn't.
What do we want from cognitive science
- explanation of /why/ anything is conscious
- definition and ability to distinguish
- explanation for why or mapping of physical states to conscious
states
*** AI foundations
artificial intelligence -- creating intelligence through skilled (art)
labor (ficial)
formally started in a 1957 conference
divide between the /cognitive science/ and /engineering/ approaches
Some early work in the /cog sci/ camp. Associative memory hierarchy
identified through analysis of reaction times for the answering of
simple questions. Time to answer generally grew for concepts higher
up the hierarchy, e.g.
: animals (semantic network)
: |
: birds
: |
: parakeet
: |
: tweety the parakeet
cached out currently in object oriented programming.
Seminal paper by Alan Turing appeared in the Journal _Mind_, entitled
"can computers think" -- introduces the /Turing test/ -- with the goal
of allowing intelligence to exist separate from human intelligence.
empiricists vs. rationalists -- AI tends to cross this border
- village law -- can't keep your goldfish in a curved bowl
- rationalists
- pure forms
- numbers really exist
- empiricists -- Rodney Brooks
- you only have access to that which has been perceived
- Hume induction has no foundation
** 2011-02-02 Wed -- no class due to Freezing of New Mexico
** 2011-02-09 Wed -- missed class
** 2011-02-16 Wed -- Phil o Mind intro part two
- functionalism :: proposed by Harry Putnam, the mind should be
understood by what it /does/. how different from /behaviorism/?
analysis through /functional decomposition/ -- would this
explicitly not investigate /emergent/ properties of
consciousness?
types of facts which can be appealed to through functional
analysis
- causal facts
- structural
- representational
three scenarios pre-qualia and anti-functionalism
- zombie world is no different
- cog scientist who lives in a world of black and white (like the
bat argument) who knows everything about blue, she learns when
she is allowed to see blue
- McGinn 1989 -- scientists announce tomorrow that they have
found the /cause/ or /correlate/ of consciousness in the brain,
then why should that set bring about consciousness. how can
there be physical causes of the /perspectival immediacy/,
/phenomenal/, and /privileged access/ of consciousness
options seem to be Metzinger or dualism
100ms delay between action and conscious experience of action
/grounding/ is the cognitive science term for bases of /understanding/
** 2011-02-23 Wed -- Don Partridge and Fernando Valenzuela
*** Don Partridge -- mechanics of neurons
**** Reflexes
: +---------------+
: +-------------->| transformer |------------+
: | +---------------+ |
: control +--+--+ +----------+ +--------+ | length
: ------>| Σ |------->| force |---->| mass |------+------>
: +-----+ +----------+ +--------+
**** Cell Composition
Nerve cells are /excitable cells/ meaning that they can change the
potential across their surface -- note: a cell is water on the inside,
water on the outside, and a lipid bi-layer separating the two, this
requires;
- ion channels :: protein molecules which form water-filled pores
through the bi-lipid membrane of a cell, these are selective to
specific ions (generally for $Na-$, $Ca++$, $Cl-$, $K+$), these
are /gated/ meaning they can be open or closed
- concentration gradients :: or a /pump/ which hydrolyzes at to "flip
over" and move molecules from one side of the cell to the other,
these require energy but can move ions up their concentration
gradient, much slower than ion channels
| | $[S]o$ | $[S]i$ |
|----------+-----------+-----------|
| $Na+$ | 145mm | 12mm |
| $K^{+}$ | 4mm | 155mm |
Cells swimming in a high-sodium low-potassium medium (as found in the
ocean or in our bodies) with low-sodium high-potassium insides.
These differentials in ions lead to voltages across the cell membrane,
which the cell can control using its /ion channels/ and /concentration
gradients/.
Potential along nerves falls off exponentially with a space constant \lambda
as follows with $\lambda \simeq 1mm$.
\begin{equation}
V\alpha = Voe-\frac{length}{\lambda}
\end{equation}
Given how quickly the potential drops off it will need to be amplified
along the way (say while traveling up a leg).
**** Firing of a neuron
gates sense the voltage across the membrane of a cell, when they hit a
certain threshold they will fly open releasing the potential in the
cell in a burst of energy, the cell then requires some amount of time
to /recharge/ before it can be excited again (like a flush toilet)
A membrane with three kinds of gates
: m n
: --------===-------------===------------
:
: -------- ------------- ------------
: ||
: ||h
: ||
De-polarization -- firing
| m | open |
| n | open |
| h | close |
Re-polarization -- resting/recharging
| m | close |
| n | close |
| h | open |
speed of gates
: fast slow
: m ------- h ------- n
**** Amplitude to Frequency Encoding
This /recharge/ period is essential to "frequency encoding", a high
potential will /push/ the cell through it's hyper-polarized /resting/
phase more quickly resulting in more frequent cell firing.
**** Movement of Action potential
An action potential moves along a neuron by discharging a series of
capacitors -- as each capacitor (+,- pair) discharges it induces its
neighbor to discharge.
: + + + + + + +
: ---------------------------
: - - - - - - -
**** Synapse --- /clasp/ in greek
the action potential releases neurotransmitters in the pre-synapse,
which trigger an action potential in the post-synapse, thus the
potential jumps from the dendrite of the first neuron to the axon of
the second.
**** Speeds
pain fibers are the slowest -- reflexes pull you hand back, but pain
is just to teach you not to do it again (not time sensitive)
| along mylenated long-term nerves | 120 m/s |
| pain fibers | ~1 m/s |
| transduction along a synapse | ~1 ms |
| aka (absolute refractory period) | |
*** Fernando Valenzuela -- learning and memory
- hippocampus :: the center in the brain for learning and memory
The famous _H.M. Patient_ had intractable epilepsy, part of the
hippocampus and the amygdala were removed and the patient lost no real
intelligence or personality but did lose the ability to form new
memories.
It is still not clear if the hippocampus is just required for
/forming/ memories which are stored elsewhere, or if the hippocampus
does both forming and storage, and it was only partially damaged.
Cab drivers in London spend a year navigating the city in mopeds with
the goal of memorizing the city. This changes the size of the
hippocampus in these drivers to have a smaller anterior hippocampus
and a larger posterior hippocampus.
- long term potentiation (LTP) :: persistent increase in synaptic
strength that can be rapidly induced by brief neural activity
Applied current to a neuron over a couple of minutes can result in
increased potentiation on the order of minutes, days, years, etc...
the /frequency/ /intensity/ and /duration/ of the stimulation affects
the time.
- cooperativity :: critical number of pre-synaptic fibers must be
activated
- input specificity :: restricted to input that recieves tetanic
stimulation
- associativity :: stimulation of weak after stimulation of strong
leads to potentiation of weak
"cells that fire together wire together"
Just a few seconds of calcium increase is sufficient to result in the
formation of short-term memories in a neuron.
Dendrites on neurons can /grow/ spines in response or as part of the
formation of memories, these changes can happen visibly on the order
of 25 minutes.
** 2011-03-02 Wed -- missed class
** 2011-03-09 Wed -- two psychology speakers
:PROPERTIES:
:ID: de820990-8743-4770-b09c-24bec12c1ee4
:END:
Basically this current induction is like drugs only without the
whole-body whole-brain effects, and it is super-cheap ($300).
*** Imaging and Modulating Brain Dynamics
- psychology :: study human behavior
- neuroscience :: understand behavior as an /emergent/ property of the
physical structure of the brain
- anatomy :: template for structure-function relationships
- neuroimaging :: non-invasive measuring of the brain
game
- can observe correlation and try to determine /criticallity/
(necessary)
- determine biological basis of many diseases and disorders (funding)
can be imaged
- anatomy
- connectivity
- chemistry
- metabolism -- FMRI
- neuronal dynamics
methods
- Diffusion Tensor Imaging DTI :: trace the /cables/ (mylenated
neuronal arms) connecting parts of the brain
- Transcranial Magnetic Stimulation (TMS) :: apply changing magnetic
field to the brain, induce electric pulse
- EEG :: attach electrodes to the brain, and can allow the subject to
run around free of wires (e.g., dolphins, rats in a maze etc...).
These are all about /brain dynamics/, with limited information on
the sources of the activity -- due to Maxwell's equation.
inversion algorithms are used to guess at sources of sensed
activity
epilepsy was a big initial application of EEG (huge signals)
EEG is a /direct/ measure of neuronal activity. Can see
background oscillation as well as discrete events.
- MEG :: does not require direct attachment to the scalp, and can
detect deep into the brain.
Fetal Alcohol Syndrome FASD -- broken wiring in the cortex of the
brain, due to drinking during pregnancy, can lead to premature
hand-off of control from the back of the brain to the cerebellum
before the cerebellum is mature enough to make good decisions (doesn't
mature until 22-23) \rightarrow *stupid teenagers*
This work is looking for abnormal cortico-cerebellar network dynamics
in FASD affected children.
Similar technique can be used to /speak/ to the brain, after listening
to enough chatter between parts of the brain it should be possible to
influence this conversation through external electrical stimulation
with Transcranial magnetic and direct current stimulation TMS and TDCS
respectively.
- 10 minutes of induced change can lead to ~1 hour of persistent
change
- 10 minutes a day for 5 days could lead to a couple of months of
effective change
could be used to cheaply change inhibitions, affect epilepsy, etc...
Using this technique to /short out/ parts of the brain can be useful
for detecting /critical/ relations between.
*** Brain Stimulation and Imaging
Vincent P. Clark
Many of our cognitive abilities may have developed in response to
natural camouflage of prey animals.
How the MIND network overcame financial problems through a DoD grant
related to camouflage.
There are /many/ tools for imaging at the MIND network.
People receiving tDCS during training were learning more than a
control group.
** 2011-03-23 Wed -- more class project discussion and neural nets
:PROPERTIES:
:ID: ada46e98-49dc-4b3f-b62c-4c2b08f14bef
:END:
*** class project discussion
interesting topics
- how does the mind cognitively represent space?
/physics and philosophy/ Heidegger
- affordence, (e.g., a chair is always for sitting, how tall can a
step be before we see it as a step)
*** more neural nets
Biological learning is entirely /unsupervised/.
(what is the scope of the biological system?)
- a /winner take all/ neural network is the first element of a self
organizing system, in this system only the single neuron closest to
an input is trained (changed) by that input
- /Hebb's Rule/: neurons that fire together wire together. Requires
no teacher and requires no non-local interactions
An example showing how non-supervised learning can be used to identify
poisonous foods.
** 2011-03-30 Wed -- two more psychology speakers
:PROPERTIES:
:ID: 7f5be9e8-15cc-4145-b619-9065557b9ebc
:END:
*** Ron Yeo -- human intelligence
**** general intelligence (/g/)
the /consensus/ perspective on intelligence, the hierarchical model
: +----------------------------+
: +----+ |
: | | General Intelligence (g) +---+ Psychology
: | | | |
: \ +--------+------------+------+ |
: | | | |
: | +----+----+ | |
: +----+----+ | | +----+---+ +---+----+
: | | | | | | | |
: | verbal | | spatial | | memory | | etc... |
: | | | | | | | |
: +-+--+-+--+ | | +--+-----+ +-----+--+
: | | | +---+-----+ | |
: | | \ | | \ Cognitive
: / | | | / | Neuroscience
The mid-level elements of intelligence tend to be positively
correlated.
**** Operational Definitions of /g/
- first principal component of a large battery of cognitive tests
- /Wechsler Adult Intelligence Scale/ Full IQ
- Ravens Progressive Matrices non-verbal test
**** The nature of /g/
- a hypothetical construct
- may or may not reflect a unitary physiological or psychological
process
**** Well-founded suspicion of tests due to misuse
- testers used to take English language tests out to Ellis Island and
send back hopeful immigrants who fare poorly on said tests
- society invests great importance in intelligence
- all states but Texas won't execute stupid enough people
- "would you rather your kids marry an ugly or a stupid person?"
- well correlated with risks of Alzheimer's Disease, Schizophrenia,
Dyslexia, ADHD, Depression, PTSD
- including alcoholism, smoking, mortality (age at death), general
health -- much of this is even true among the top 1% of intelligence
**** Heritability
$h2=2(rMZ-rDZ)$, in which $h2=0.6$ meaning roughly 60% of an the
variance of an individuals intelligence in a population can be
explained by genetic factors, leaving 40% up to environmental factors.
This sort of thing can be determined by comparing/contrasting /shared/
and /unique/ environmental features between genetically similar
individuals.
**** Genetic Factors
- autosomal :: the relevant genes are /not/ located on sex chromosomes
- pleiotropic :: of course, the related genes do plenty of other
things as well
- polygenic :: with about 25,000 genes, 60-80% are expressed in the
brain, with very little evidence for single-gene effects
Ron's been looking into the hypothesized that personal mutation level
in the genome could be related to intelligence.
- symmetry is correlated with intelligence
- beauty is weakly correlated with intelligence
- both are weak indicators of if you are /built to plan/ or somewhat
mutated
- the amount of /deletion mutations/ in your genome is generally
negatively correlated with your intelligence
Given all this, no one has found specific genes which seem to be
individually related to intelligence.
87% of an infants energy budget is devoted to brain development.
**** Graph theoretic view of the brain
- nodes are /functional clusters/ in the brain
- edges are connections between these centers, and the brain is a
/small world/ network
the clustering coefficient doesn't seem to relate to general
intelligence, rather the number of length (shorter is better) of
inter-node connections is positively correlated with intelligence
*** Derek Hamilton -- behavioral/neuro-biological constituents spatial navigation
- space and navigation are ubiquitous
There is well defined circuitry in mammals supporting spatial
navigation, and this shares many mechanisms with the structure
supporting long-term memory, so it appears that spatial abilities have
/piggy backed/ on mechanisms originally developed to support long-term
memory.
what is learned when an animal successfully navigates a maze.
- it seems animals generally are better at learning spatial relations
rather than directional relations, e.g. west instead of left
- distal cues are used over other sources of navigation information
- /place cells/ in the hippocampus fire in relation to places, however
many of these are also conditioned on the direction in which the
animal is moving, as well as the place
- the /most important/ frame of reference is the /local/ frame of
reference
** 2011-04-06 Wed -- psychology and neuroscience
:PROPERTIES:
:ID: 7299d4ff-1fea-45ae-8c1e-cadb50b6751f
:END:
*** Akaysha Tang
(see http://atlab.unm.edu/index.php/Main_Page)
- novelty detection should be parallel and distributed through the brain
- how does Gabba (inhibitory neurotransmitter) affect novelty
detection in a network
** 2011-04-27 Wed -- sign language psycho-linguist
*** Jill Morford -- Critical Period to Language Acquisition
:PROPERTIES:
:ID: b3efacb5-a4b9-4355-9603-78e2bcbad7da
:END:
ASL is *not* a signed form a English, but rather is its own language
with its own lexicon and grammar.
French sign language is much more similar to American sign language
than is British sign language.
conclusion: the critical period is critical for efficient and rapid
processing of language, rather than the ability to construct complex
linguistic constructs
**** critical period
The idea of critical period is not unique to language
The critical period
- children begin stringing words together around the age of two
- children cease to learn new linguistic constructs around puberty
Evidence that the younger an individual at emigration into the US, the
better their English proficiency, explanations
- critical period
- sociolinguistic factors
- cognitive decline
It seems that brain plasticity could be related to the critical
period.
Linguists believe that the hierarchical structuring of language is
innate, and all that is required during the critical period is for
these innate structures to be /triggered/ through exposure.
**** linguistic isolation during the critical period
- Curious Monarchs :: at three times in recorded history, monarchs
have isolated children from language to investigate the effects
of growing up without language, in all cases the results were
contaminated by language, or the children died
- Genie :: neglected child
- did acquire negation plural progressive
- did not acquire pronouns, movement rules, auxiliaries
- Homesign :: when deaf children are raised in loving families but are
not signed to (more common in the 60s and 70s), often these kids
invented a way to communicate through gesture (ubiquitous)
- points to reference nouns, and /temporal points/
- iconic gestures (like visual onomatopoeia), are likely to function
more like verbs, can be moved spatially to associate the verb with
a noun
- generally isolate alphabet of core motions which are re-purposed
to a wide array of situations
Homesigners generally /produce/ language rather than /perceive/
language as do normal children.
**** post-critical period language acquisition
- outperformed by early learners
- highly variable performance
- late learners have incomplete /grammatical/ knowledge although they
tend to be able to learn every other part of the language
Second language learners are better than post-critical period learners
largely in their ability to /recover/ when they've missed a sign or
misunderstood a word.
*** Melanie Moses -- Scalable RADAR
Talk from IEEE Alife April 2011
- scales in ant colonies
- Argentinian leaf cutters with millions of ants and ages ~50 years
- small ant colonies inside of a single acorn with ~12 members
- ants often don't use any pheromones but with rather often collect a
pile of seeds by themselves without ever asking for help
**** immune system
- like a distributed metabolic system with many little separate hearts
(lymph-nodes) each of which is responsible for an area of
enforcement
- the immune system does not show the 3/4 power law shown in other
biological systems, rather the speeds are generally equal across
species sizes --- makes sense, as there's great selective pressure
- this could be due to the architecture of the lymphatic system,
both the number and size of lymph-nodes scale with size (but not
directly)
**** repeated sampling
repeatedly searching until you find something
- searching is a really effective way to search if you keep looking
whenever you don't find anything
- in ants this is like an ant stopping its search when it found some
seeds, but not telling other ants about the seeds
- in immune systems this is like T-cells never communicating back to
the lymph-node, but continuing to circulate (search) until it runs
into an inflamed region with an infection
** 2011-05-04 Wed -- Rec E. Jung on Creativity
:PROPERTIES:
:ID: 020f9474-b30a-4225-950b-8aa7bcd1143d
:END:
on the relationship between intelligence and creativity
neuro-mythologies
- genius is required for creativity
- mental illness is required for creativity
modes and domains
| processing \ domain | emotional | cognitive |
|---------------------+-----------+-----------|
| deliberate | | |
| spontaneous | | |
/good/ ideas require /many/ ideas
study over a number of subjects
- high IQ subjects had a negative correlation between naa and
creativity
- low IQ subjects had a positive correlation between naa and
creativity
Transient hyper-frontality: down-regulation of the frontal lobes to
allow novel connections between disparate regions of the brain.
* Final Paper -- Thomas Metzinger
ego-machine.pdf (code, video)
** Meta
- 8-10 pages including references (no longer than 10 pages)
- due the Monday of finals week
- would be good to get it in early
- web references should include an access date
** Notes: There is no Self -- Metzinger
- philosopher
- theory of consciousness...
- consciousness doesn't exist
- rather is a trick the brain plays on itself to help in planning
and communication
- related to pre-frontal cortex
- Rex Young, intelligence, related
- Derek Parfit
- read this Metzinger book The Ego Tunnel
* Footnotes
http://www.prnewswire.com/news-releases/apache-innovation-bolsters-ibms-smartest-machine-on-earth-in-first-ever-man-vs-machine-competition-on-jeopardy-quiz-show-116151274.html
http://blog.reddit.com/2011/02/ibm-watson-research-team-answers-your.html
http://www.apache.org/