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.
The ability for the Na + /Ca 2+ exchanger to reverse direction of flow manifests itself during the cardiac action potential. Due to the delicate role that Ca 2+ plays in the contraction of heart muscles, the cellular concentration of Ca 2+ is carefully controlled.n fact, the Na + /Ca 2+ exchanger is in the Ca 2+ efflux position most of the time. However, during the upstroke of the cardiac action potential there is a large influx of Na + ions.