The frontal lobe contains most of the dopamine-sensitive neurons in the cerebral cortex. The dopamine system is associated with reward, attention, short-term memory tasks, planning, and motivation. Dopamine tends to limit and select sensory information arriving from the thalamus to the forebrain.
Na + concentration is lowered, indicating that Na + in-flux is responsible for the rising phase of the action po-tential. Their data also suggested that the falling phaseof the action potential was caused by a later increase inK+ permeability.
1 Once action potential starts, it travels to a synapse. 2  Stimulus must cause sufficient movement of Na+ and K+ to depolarise the membrane and. cause an action potential. 3  Threshold stimulus â impulse that causes an action potential.  Stimulus transmits an impulse at a constant and max strength.