1. A method of treating a brain disorder in a patient having a cardiac cycle, a vagus nerve, and a brain, the method comprising: detecting at least a portion of the cardiac cycle of the patient; applying to a selected location on the vagus nerve of the patient, in response to having detected the portion of the cardiac cycle of the patient, a pulsed electrical signal configured to increase afferent activity on the vagus nerve to be conducted thereby to the brain to treat the brain disorder, the pulsed electrical signal comprising a plurality of microbursts, wherein each microburst other than a last of the plurality of microbursts is separated from an adjacent microburst by an interburst interval, and at least one interburst interval is varied from at least one other interburst interval, wherein each microburst of the pulsed electrical signal comprises: from 3 to 6 pulses per microburst; a plurality of interpulse intervals, each interpulse interval being between adjacent pulses of the microburst, each interpulse interval ranging from about 5 to about 10 milliseconds, wherein at least one interpulse interval of the plurality of interpulse intervals within the microburst is varied from at least one other interpulse interval of the plurality of interpulse intervals within the microburst; and a microburst duration less than or equal to 100 milliseconds.