1. Cycle 2: Structure Defines Function
Physiologist (function): if we could document all the connections…would we understand how they lead to behaviors?
Anatomist (structure): we can never discover brain computation without revealing its basic connectivity.

2. Cycle 2: Hierarchy of Multiple Parallel Loops
Brains move bodies
Sensors help make better movements
(or no movement)
Simple sensation-to-action loop.
Bigger brains ->multiple parallel loops
Idea: phylogetically newer loops modify old loops.
But “age” of structures of given brain is the same…
phylogenetic age gives more opportunity for older structures to be modified
Modifying inputs of ‘old’ structures could change the content of their output. (e.g. Amygdala)

3. Cycle 2: Hierarchy of Multiple Parallel Loops
[p.32] …there is nothing in the physical world by itself that would predict a priori the response of a brain to a stimulus. It is often largely the state of the brain that determines the behavioral outcome…
[yet] we do not know the neuronal processes underlying the word “state”.

4. Cycle 2: Hierarchy of Multiple Parallel Loops
[p.33] What is meant by ‘calibration’?

5. Cycle 2: Large-scale Organization of the Brain Web
[p.34] the frequency of various brain oscillators are kept relatively constant [across species] even as the numbers of neurons have increased enormously
RTs differ as do neuronal response latencies…e.g. 3/5 rule.

6. Cycle 2: Scaling problems in brains of various sizes

7. Cycle 2: Scaling problems in brains of various sizes
LOCAL: time to propagate to distant regions
RANDOM:

8. Cycle 2: Scale-free systems
No Bell curve; power law
No one typical example in the mix
No qualitative difference in the big middle and small units
Tensegrity – provides scale-free architecture.

9. Cycle 2: Cortical column

10. Even in L4, the vast majority of excitatory synapses arise
locally within cortex
40 %
30 %
<10 %
Thalamus
(20 % long corticocortical
excitatory connections)

11. Two competing world views: How is perception shaped?
Empiricism
Nativism
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