Download Lecture 2: Foundations September 10, 1999

Neuroscience
1. Brain Organization
2. Single Neuron Computation
3. Six Organizational Principles of Neural Computation
1. Brain Organization
Central Nervous System
Brain
Cortex
Neocortex (sensory & cognition)
Limbic System (emotion & learning)
- Amygdala (emotion)
- Hippocampus (learning)
- Cingulate Gyrus
Brain Stem (autonomous body functions)
- Hypothalamus (homeostasis)
- Pons (walking)
- Medulla (breathing, heart rate)
Cerebellum (balance & motor planning)
Neocortex
Limbic System
Hippocampus
Levels of Brain Organization:
- Behavior (e.g., vision vs memory)
- Systems (e.g., hippocampus vs visual cortex)
- Neural networks
- Neurons (computational unit)
- Synapses
- Molecules
Neuronal Facts:
- 1000 billion neurons
- 105 neurons per 1mm3
- 1000 synapses per neuron
- 3% (sparse) connectivity within 1mm2
- 90%/10% excitatory/inhibitory neurons
- 1 msec neuronal processing time
- 50 spikes per second (i.e., 50 Hz)
2. Single Neuron Computation
Single Neuron
Neural Firing
Neural Pulse
Mathematics of Neural Firing
3. Six Organizational Principles of
Neural Computation
1. Activity-specific neurons
2. Neuro-behavior correspondence
3. Hierarchical organization
4. Laminar organization
5. Topographic organization
6. Neurotransmitters as messengers
1. Activity-specific neurons
Firing activities of
location-sensitive neurons
2. Neuro-behavior correspondence
Firing activities of
direction-sensitive neurons
3. Hierarchical organization
“extensive consultation and consensus building”
4. Laminar organization
5. Topographic organization
6. Neurotransmitters as messengers
Brain is a Computing “Machine”