Download NEOCORTICAL CIRCUITS

NEOCORTICAL CIRCUITS
specifications
where are we coming from?
• human-based computing
– using typically human faculties
• associating words with images
-> labels for image search
• locating objects in images
-> database for computer vision
• provide common sense facts
-> for more "intelligent" computing
– lure millions into playing that game
• nature-inspired computing
– annealing
– genetic algorithms
– swarm intelligence
• limitations to "computers"
– problems no "computer" can solve
– problems that require unreasonable resources
• brain-inspired computing
brain-inspired computing
• stagnant artificial intelligence
• the human brain
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an (almost everywhere) identical 6-layer structure in the neocortex
with a columnar organization
genetically determined dedicated areas hierarchically connected
laminar computing machine, massively parallel, special “algorithms”
• memory
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the neocortex
the neocortex
the neocortex
the neocortex
stores sequences of patterns
recalls patterns auto-associatively
stores patterns in an invariant form
stores patterns in a hierarchy
• structure of the brain
– the neocortex: flows, interconnect, operation
– overall architecture with the hippocampus on top
• hierarchical temporal memory
• “towards a mathematical theory of cortical micro-circuits”
• brain-computer interfacing: non-invasive probing, transducers,
invasive probes
simplified brain architecture
hippocampus learns long-term memories
and sends the info to the cortex
the “old” long term memory
for events, places, objects
cerebral cortex
hippocampus
striatum
prefrontal cortex
olfactory cortex
amgydala
auditory cortex
somatosensory cortex
visual cortex
motor cortex
hypothalamus
basal
ganglia
thalamus
limbic system
parahippocampal gyrus
the “old”
motor system
the “old”
timer
cerebellum
sensory organs
motor organs
the hippocampus: on top of it all
• unexpected patterns get passed
higher and higher up–
so truly new experiences
will reach the hippocampus
• aging example:
- fitting into past memories
so less and less is seen as new
– without the hippocampus
no new things
can be learned
• unlike the neocortex,
the hippocampus has
heterogeneous structure
touch
with specialized regions.
• only form permanent memories
if experience it over and over,
in reality or by thinking of it,
so that it gets passed “down”
to cortex.
audition
vision
Hawkins' model (of the world)
“causes”
“beliefs”
people
cars
buildings
words
songs
ideas
world
patterns
senses
cause1
cause2
cause3
cause4
cause5
cause6
representations
of causes
0.22
0.07
0.00
0.63
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0.08
our intelligent
cortex
machine
what should the intelligent machine do?
1 discover causes in the world
2 infer novel input
3 predict future
4 direct motor behavior
intelligent machine
the world
1 discover causes in the world
2. infer novel input
3. predict future
4. direct motor behavior
causes
representation
of causes
sensory data
each node: discovers causes (of its input), passes beliefs up, predictions down
each node: stores common sequences,
changing sensory data forms stable beliefs at top
stable beliefs at top form changing sensory predictions
benefits of "hierarchical" structure
1)
2)
3)
4)
shared representations lead to generalization and efficiency
hierarchy matches spatial and temporal hierarchy of causes in world
belief propagation techniques ensure
all nodes quickly reach mutually compatible beliefs
affords mechanism for attention
how does each node discover causes?
1)
2)
learn common spatial patterns
learn common sequences of spatial patterns
ad 1:things that happen at the same time are likely to have a common cause
common patterns:
remember
uncommon patterns:
ignore
ad 2:things that happen consecutively might have a common cause
time
common sequence:
assign to cause
common sequence:
assign to cause
uncommon sequence:
ignore
simple “htm” vision system (32x32 pixels)
Level 3
Level 2
Level 1
4 pixels
columnar organization of the microcircuit
• upward flow:
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L1
L2
L3
L4
L5
L6
converging inputs arrive at layer 4.
form a passing connection in layer 6
layer4 sends axons to 2 and 3,
layer 2,3 send often axons
up to the next higher region.
columnar organization of the microcircuit
L1
L2
L3
L4
L5
L6
• downward flow:
-layer 6 cells to layer 1 of lower regions.
- layer 1 spreads this input out,
- picked up on by dendrites of layers 2,3, 5
- axons from 2 and 3 form synapses in 5
and excite cells in 5 and 6
columnar organization of the microcircuit
timing circuit
motor functions
nonspecific thalamus
Mapping between neocortex hierarchy and HTM hierarchy.