Which is an example of cooperativity?
Select all that apply.
(a) Input neurons A and B fire a burst of action potentials simultaneously.
(b) Output neurons I and II fire a burst of action potentials simultaneously.
(c) Input neurons A and B fire a burst of action potentials at the same time that output neurons I and II fire a burst of action potentials.
(d) Input neurons A and B fire a burst of action potentials at the same time that output neurons I and II are depolarized.
(e) Input neuron C fires a burst of action potentials at the same time that output neuron II is active.
The correct answer and explanation is:
The correct answers are (c) and (d).
Explanation:
Cooperativity refers to a phenomenon where the activity of multiple elements, such as neurons or molecules, influences each other to create a collective effect. In the context of neurons, this typically involves the simultaneous or sequential firing of multiple neurons, resulting in enhanced or synchronized responses.
- (c) Input neurons A and B fire a burst of action potentials at the same time that output neurons I and II fire a burst of action potentials.
This is an example of cooperativity. The simultaneous firing of input neurons A and B, along with output neurons I and II, suggests a cooperative interaction between the two sets of neurons. The inputs and outputs are likely influencing each other, resulting in synchronized activity, which is a key aspect of cooperativity. - (d) Input neurons A and B fire a burst of action potentials at the same time that output neurons I and II are depolarized.
This is another example of cooperativity. While the output neurons may not be firing action potentials yet, their depolarization indicates that they are being influenced by the simultaneous firing of the input neurons. Depolarization is often a precursor to an action potential, and this cooperative interaction between the input and output neurons leads to a collective change in the system.
The other options do not demonstrate cooperativity:
- (a) and (b) only describe independent firing of neurons and lack any interaction between input and output neurons.
- (e) does not involve simultaneous action potentials or a direct interaction between input and output neurons, so it is not a cooperative effect.