Cognitive science experiments have shown that humans can rec

Cognitive science experiments have shown that humans can recognize simple objects visually shown for as short as 13 msec. Assume that all the neurons in our brain have myelinated axons, the length of nodes of Ranvier is uniformly 1 mu m, and the radius of the axon is 0.5 mu m Using the typical parameter values, calculate the neural signal transmission speed (no need to derive the equation for the transmission speed). Let\'s assume that the visual cognition process consists of multiple neurons If each neural communication is a single one-way neural signal transmission over the distance of 10 cm, how many neural communications are needed for humans to recognize a visually shown object?

Solution

(a) In normal condition, the signal transmission speed is calculated by the formula: V = 2.5D where V is velocity of signal transmission speed and D is diameter of axon.

Here the radius of axon is given: 0.5 micro meter. Hence the diameter of the axon is 0.5 * 2 = 1 micro meter.

Therefore the speed of transmission signal = 2.5 * 1 = 2.5 m/sec.

(b) Since, here it is given that humans can recognize simple objects visually shown for as short as 13 msec. The velocity of signal (calculated above) = 2.5 m/sec.

Therefore the distance travelled by signal in 13 m sec (13 * 10^-3 sec) = 13* 10^-3 * 2.5 = 32.5 * 10^-3 meter.

Since one neural communication requires for 10cm (10^-1 meter), therefore total no. of neural communication requires for 32.5 * 10^-3 meter. = 32.5 * 10^-3 / 10^-1 = 32..5 * 10^-2.