B737-800 Captain reported a ground conflict during taxi-in to Gate with a truck requiring aggressive braking action to avoid a possible collision.

Narrative

Taxiing on ramp enroute from a Spot X entry to Gate XX. As the aircraft approached the marked roadway across ramp between Terminal X and Y near Gate XY; a white pickup truck with a marking 'XXXX' was poised to cross from south to north - the truck was stopped; the Driver looked directly at the taxiing aircraft approaching roadway at slow speed; but nearing the crossing; the Driver then started across the roadway requiring me to apply aggressive braking to the aircraft; also turning on the landing lights (although it was still daylight) to make sure the Driver saw us. The truck then turned left (west) toward Gate XX. I asked First Officer to have Ramp Tower to note truck and location and time. Additionally; I had an FAA Inspector in the jump seat and he indicated he would file a report.Cause - I couldn't begin to understand what; if anything; was going through the mind of the pickup truck Driver when he decided to proceed so closely across the path in front of a moving 142;000 lb aircraft.Suggestions - Start citing dangerous drivers on airport ramps and taxiways system wide - remove driving privileges when appropriate.