Threshold in the nervous system.

[APPLEhead]

Can someone please explain/tell me what a threshold is? I know it has to do with the nervous system. I can't find the definition in NOB

[pi]

Like a threshold potential or something else?

[ligands]

stimulus threshold?
its the threshold a stimulus must reach before a response occurs
for example if the threshold is at 10 (random number) but the stimulus only occurs at 8 the response will not happen but if the stimulus occurs at 18 the response will occur

[drcrowthorne]

The threshold is like how much sensory input is needed to excite a neuron. For example, like you said, if the neuron's threshold is 10, it will only get exited at ten. Not 7, not 9, not 9.5, ONLY 10. What actually happens is, if there is enough excitement to the neuron, the action potential (which is basically just a rush of ions) gets transmitted, and the neuron is 'excited'. But, if there isn't enough stimulation, the rush of ions doesn't happen, and so the neuron doesn't get excited.

[APPLEhead]

This is from my notes (I didn't write it):

"Net flow of positive charges into cell; cell is depolarised, moving membrane potential closer to threshold."

It was written under excitatory synapse.

[APPLEhead]

OHHH, okay. Thanks guys!

[Daenerys Targaryen]

what would be an appropriate definition if we were to define it?
the mark in which must be exceeded for an action potential to be made?

[ligands]

the threshold a stimulus must reach before a response is achieved
'response' would include all the neuron based stuff such as action potential and all that garbage

[Russ]

what would be an appropriate definition if we were to define it?
the mark in which must be exceeded for an action potential to be made?

The membrane potential which it is necessary to achieve, in order to allow the propagation of an action potential along a neuron

edit, or the generic above for all sorts of signal thresholds

[Daenerys Targaryen]

ah, thanks