Development Notes Volume 1 Chapter 6

27. - ChatGPT 4o Basic Calculation 2024-09-26

I have finally found a way to get reliable output from ChatGPT. This helps me cross check calculations going on in the Neuron Simulator. This is a basic calculation for a set of Dendrite biophysics:

Calculate Dendrite Rm, Cm, Ra
given:
 Length = 100  µm  
 Diameter = 1.5  µm
 RMSpecific = 10 kΩ/cm^2 
 CMSpecific = 1  µF per cm^2
 RASpecific = 0.1 kΩ per cm
Show work

This should produce:

  • Membrane resistance (): .
  • Membrane capacitance (): .
  • Axial resistance (): .

and in a second command to Chat:

Apply a step input of 25 pA for 70 ms. 
Calculate the membrane steady-state voltage at 60 ms. 
Show details.
This should produce:
  • Steady-state voltage (V∞): .
  • Membrane time constant (τm):.
  • Membrane voltage at : .

Notice:

  • Enter from Greek alphbet. µm rather then um
  • Don't use "per" for things like 1uF per cm^2. Use 1uF/cm^
  • Don't use "·" (middle dot). Use "*" (multipication)
  • Always enter "clear memory" or you will perpetuate hallucinations
  • Use one 'Calculate' at a time.

26. - ChatGPT 4o Hallucinating 2024-09-14

Working more with Chat I attempted to use the output from to cross-check some calculations my simulator makes during its operation. I could not justify a difference I came to. During the operation the simulator was converting centimeters to micrometers and was getting a different answer than Chat was delivering.
I worked and worked to find the source of the error and finally realized that it came from Chant - it was hallucinating!
I fed the correction back into Chat and it responded that I must have made a typo and gave me back the same wrong answer.
No matter how I rephrased the question Chat insisted that I was wrong.
This experience made me question my earlier assumption about Chat and the future of AI.

25. - Cross check with ChatGPT 4o

I thought it would be interesting and informative to check the way I calculate the membrane voltage in the simulator.
It was more than assuring - it was astounding.

This is the text presented to ChatGPT 4o for analysis:

Calculate the membrane voltage of a dendrite that is 100 um long, 1.5 um diameter, input resistance of 2,122,065 KOhm and capacitance of 4.71 pF after a 10 pA step that is 10 mSec wide at 16 MSec.

And this is the return:

I set up the simulator

... and using the mouse found the 16 mSec point and that the curve passed through 7.3 mV

Amazing
ChatGPT 4o is much more than a simple spell checker. The damn thing is thinking about and solving problems.