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 sudden but short-lived depolarization of a region of the plasma membrane during an action potential is caused by a sudden massive, but transient, influx of Na+ ions through opened voltage-gated Na+ channels in that region. At the resting membrane potential these voltage-gated channels are closed.