1. How Did Nature Solve the information processing problems through the development of neural networks as well as the subsequent training and coordination with other networks? Daniel Carlin, Daniel Cook, Joshua Mendoza-Elias Macro Micro Nano Macro Micro The Physical and Chemical Limitations that NatureOvercame were: solubility, dispersibility, surface area , conduction, signal modulation The Problem Nature HAS in Disease is:the severing of a neural network: paralysis, loss of sensation. Nano LTP-KO: NMDA Receptor AgonistCPP No change synapticefficacy No Learning Loss of memory

2. How Did Nature Solve the information processing problems through the development of neural networks as well as the subsequent training and coordination with other networks? Daniel Carlin, Daniel Cook, Joshua Mendoza-Elias Macro Micro Nano Macro Micro The Physical and Chemical Limitations that NatureOvercame were: solubility, dispersibility, surface area , conduction, signal modulation The Problem Nature HAS in Disease is:the severing of a neural network: paralysis, loss of sensation. Nano 3. Nervous System: FUNCTION

Receptors collect information through mechanical or chemical changes to protein structure.

Receptors cause neurons to fire.Intensity is modulated by frequency.

Firing are additive.The aggregate of neural signalling determines the output of a network.

The subnetworks may interact with larger networks.

Large network come to control many subnetworks

-e.g. Homeostasis, visual pathways, audition, vestibular system, motor control, visceral motor system.

Cognition: Short terms memory, Long term memory, emotional regulation

4. Function continued

Evolutionarily, the nervous system is intended to:

(i.) regulate physiological processes

(ii.) collect information about an organismss environment in 5 dimensions (5 senses).

(iii.) prompt innate behaviors to react to environmentprogrammed behavior

(iv.) prompt learned behaviors to interact with the environmentcognition

(v.) Override control with other scripts:

Breathing, reflexes, Fight/Flight

5. Component Design Nervous System by function CNS (encased in bone) PNS Brain Spinal Chord Somatic System Autonomic System Parasympathetic Enteric Sympathetic Movement Coordination Receive external stimuli 8 cervical 12 thoraic 5 lumbar 5 sacral 11 coccygeal Cerrvical Spinal: C1-C4 Brachial Plexus: C5-T1 Lateral Chord: C5-C6 Posterior Chord: C6-C8 Medial Chord: C7-T1 Rest Relaxation Digestion Flight/Fight 6. Component Design Continued 7. Component Design continued 8. Material Selection

Bone encasement for CNS

-Neurons!!!Different classes/morphologies are generated through growth factors and stimulus

-Myelin Sheath: For insulation and propagation of action potentials.

80% lipid 20% protein

Myelin basic protein (MBP)

Myelin Oligodendrocyte glycoprotein (MOG)

Transmission electron micrograph of a myelinated neuron. Generated at the Electron Microscopy Facility at Trinity College, Hartford, CT 9. Material Selection: Neurons Sensory Neuron - Converts external stimuli to electrical signals - Chemoreceptors (e.g. olfactory signals) - Mechanoreceptors (e.g. joint position detection) Motor Neuron: - Stimulated by interneurons (small feedback loops or from ANS/PNS) - Activates effectors (glands, muscles, ...) Interneuron: - Data processing, stimulated by: - sensory neurons - other interneurons or both. - many unknown types remain A: Cortical pyramidal cell - primary excitatory neurons of cerebral cortex B: Purjinke cell of cerebellum.Transmit output of cerebral cortex C: Stellate cell - provides inhibitory input to cerebral cortex Example neurons from the brain: In Out Process Basic building blocks of nervous system are neurons. Hundreds of different types, many uncatalogued. Three main categories: 10. Material Selection: Glia in the CNS - Structural & metabolic support (feed neurons)- Transmitter reuptake: express transporters for neurotransmitters - Regulate ion concentrations (potassium) - Act as immune cells of the nervous system - Responsible for myelin sheathing of axons - Single oligodendrocyte myelinates 10-15 axons - Modulates axon conduction speed Astrocytes Microglial cells Oligodendrocyte Approx. 3:1 ratio of glial cells to neurons in the brain Modulate signal propagation and neurotransmitter uptake at the synaptic cleft Provide scaffold for neural development, help in injury recovery 11. Facts & Figures on Neurons in Brains

Neocortex

Number of neocortical neurons (males) = 22.8 billion (Pakkenberg et al., 1997; 2003)

Average number of neocortical glial cells (young adults ) = 39 billion (Pakkenberg et al., 1997; 2003)

Brain Average number of neurons in the brain = 100 billion Average number of glial cells in brain = 10-50 times the number of neurons Cerebral cortex: Total number of synapses in cerebral cortex = 60 trillion (yes, trillion) * (from G.M. Shepherd, The Synaptic Organization of the Brain, 1998, p. 6). However, C. Koch lists the total synapses in the cerebral cortex at 240 trillion (Biophysics of Computation. Information Processing in Single Neurons, New York: Oxford Univ. Press, 1999, page 87). http://faculty.washington.edu/chudler/facts.html

Brain requirements:

Brain utilization of total resting oxygen = 20% Blood flow from heart to brain = 15-20% Blood flow through whole brain (adult) = 750-1000 ml/min

Fault tolerance:

1 neuron dies each second in the brain

Functioning humans

Brain Brain Composition Whole Brain (%) Water77 to 78 Lipids10 to 12 Protein8 Carbohydrate1 Soluble organic substances2 Inorganic salts1 processing elements 10 14synapses element size 10 -6m energy use 30W processing speed ~100Hz 12. Materials Performance http://vadim.oversigma.com/MAS862/Project.html Number of neurons (adult)*20,000,000,000 - 50,000,000,000 Number of neurons in cerebral cortex (adult)*about 20,000,000,000 (some sources have incorrect number 8,000,000) Number of synapses (adult)1014 (2,000-5,000 per neuron) WeightBirth 0.3 kg, 1 y/o 1 kg, puberty 1.3 kg, adult 1.5 kg Power consumption (adult)20-40 Watts (0.5-4 nW/neuron) Percentage of body2% weight, 0.04-0.07% cells, 20-44% power consumption Genetic code influence1 bit per 10,000-1,000,000 synapses Atrophy/death of neurons50,000 per day (between ages 20 and 75) Sleep requirement (adult)average 7.5 hours/day or 31% Normal operating temperature37 2C Maximum firing frequency of neuron250-2,000 Hz (0.5-4 ms intervals) Signal propagation speed inside axon90 m/s sheathed,