Question

Synaptic delay lasts for average of
A. 0.1ms
B. 0.3ms
C. 0.4ms
D. 0.5ms

Answer 1

Hint: The synaptic delay is the time essential for the conduction of a signal across a synapse. The interval between the arrival of a nerve impulse at the very ending of a presynaptic fiber as well as the start of the postsynaptic potential. In synapses with a chemical transmission mechanism, a normal synaptic delay lasts from 0.30-0.5 milliseconds to several milliseconds. During this period, most of the mediators are released by presynaptic endings under the influence of nerve impulses.

Complete answer:
Synaptic neurotransmission is altered at cortical connections throughout one's life. Varying the amplitude of the postsynaptic reaction is one mechanism that generates flexible signalling in neural circuits. The timing of the synaptic response may also play an essential role.
The synaptic delay at a single end-plate patch has a minimum value, at ${20^ \circ }C$, of 0.4 to 0.5 ms along with a modal value of about 0.75 ms. There is considerable fluctuation of the measured intervals during the series of nerve impulses; over 50 % this occurs within a range of 0.5 ms, the rest being spread out in decreasing fashion over a further 1 to 4 ms.
Option A – 0.1ms
It is not the right answer to the question as the average time is 0.4 ms.
Option B- 0.3 ms
0.3 millisecond is considered as normal duration but its not average duration.
Option C- 0.4 ms
This is the correct answer to the question as the average duration of synaptic delay.
Option D – 0.5 ms
The synaptic delay of 0.5 millisecond is considered normal but it is not average duration.

So the right answer to this question is option C – 0.4 ms.

Note: The synaptic delay is practically not present in synapses with an electrotonic transmission. These latency fluctuations are displayed to be a statistical consequence of the quantal procedure of transmitter release. The contribution of different factors to the minimum synaptic delay are discussed.