1. Basic Structure of a (most) Neurons
Dendrites
ell body
Axon

2. Basic Functional Parts of Neurons
Not all neurons have this same general shape – e.g., in spinal ganglia

3. Neurons come in different shapes

4. Neurons normalky have a small electrical charge “Resting Membrane Potential”
Time
Voltage Display

5. Source of the Resting Membrane Potential (Because this quite technical , Feel free to not pay any attention to this slide)
Specialized molecules pump ions into and out of the neuron (Na+ out, K+ in), yielding different concentrations of these ions inside vs. outside of the cell. In effect, the pump creates Na+ and K+ “batteries”. (A big part of the neuron energy demand)
Specialized channels allow more or less of these ions to flow in (or out) of the cell, in effect “dialing in” more or less of each “battery”

6. Feel free to not follow the next two slides…

7. Membrane potential, Sodium (Na+) & Potassium (K+)
Outside
Outside
(Outside)
(Outside)
Na+
Na+ K+ K+
RNa+
RK+
RNa+
RK+
-90 mV
+40 mV K+ K+
Na+
Na+
(Inside)
Inside
(Inside)
Inside

8. Source of the Resting Membrane Potential (Because this quite technical , Feel free to not pay any attention to this slide)
Other ions also contribute, so it’s not as simple as just Na+ and K+…
Equivalent electrical circuit:
Membrane
Potential
+40
-90
-70

9. Okay – no more electrical circuits

10. How Neurons communicate (basically)
If a neuron’s membrane potential gets sufficiently LESS negative (~ - 50 mV), this can trigger an “Action Potential”
The Action Potential goes down the axon, and at the end (synapse) causes the release of chemicals onto the next cell
The Action Potential is an “all or none” signal (i.e., the neuron
can send only one size action potential)
Those chemicals then either excite or inhibit that cell.
“Excitatory” or “Inhibitoty Post Synaptic Potential”

11. “Integration” of excitatory inputs

13. The best analogy for an action potential
There is a threshold for triggering action
It is self limiting
It is “all-or-none”
There is a minimum inter-flush interval
If you flush too soon after previous flush you can get only a partial flush

14. Action Potential Propagation – like a burning fuse

15. How neurons ultimately send a signal – Synaptic Transmission

16. Neurotransmitters
Glutamate – the major excitatory neurotransmitter in the brain
GABA - major inhibitory neurotransmitter in the brain
Acetylcholine - many different actions in the brain; neuromuscular junction transmitter
Serotonin – many different actions; associated with mood, sleep, perception (LSD)
Dopamine – many different effects; associated with reward, movement (PD)
Opioid peptides (endorphins) – modulate pain signals
Substance P – pain signaling
Many others (adrenaline, noradrenaline, oxytocin…)

17. Summary of basic information processing in the brain
Action Potential
Synapse…
Action Potential

18. Analogy of how neurons communicate

19. Physiological plasticity
Synapses are not static:
With repeated use can show “habituation”
With intense use can become stronger (“long-term potentiation”)
Simultaneous strong inputs can potentiate each other (“fire together, wire together”)
Harris & Cotman, 1986

20. How neurons send a signal – The “Action Potential”

21. But it’s not so simple - Excitation and Inhibition

22. Spindel Cells – aka “Von Economo Neurons”
Constantin Alexander Freiherr von Economo von San Serff
Constantin Economo von San Serff
Constantin Freiherr von Economo
Example of “Fork cell”
found with VENs

23. Excitement about Von Economo Neurons
Much early excitement at their re-discovery
Originally found only in humans and great apes
Then also found in dolphins, whales and elephants
Implications in higher order social interactions!?
Most recent evidence is that they are also found in:
hippopotamus, cow, manatees, seals, sheep, deer, horse, pig, rock hyrax
Still interesting because their numbers are reduced in early-onset schizophrenia, and behavioral variant of FTD in which empathy, social awareness and self- control are seriously compromised