A system comprising: a non-invasive nerve stimulator for peripheral nerves, including the ulnar and/or median nerves, configured to be fitted proximate the left and/or right arm, wrist or hand of a user , to stimulate the median and/or ulnar nerves using at least one stimulus, the nerve stimulator comprising: a stimulus generator to generate at least one stimulus; an applicator to apply the generated stimulus to the arm, wrist or hand of the user , the applicator comprising at least one stimulus interface to apply the stimulus to the user's skin, proximate to the anterior or ventral side of the user's arm, wrist or hand; and at least one user biometric measuring sensor , embodied in or proximate the applicator , to monitor and determine physiological parameters associated with the user , including any one or more of the following: heart rate, HR, heart rate variability, HRV, temperature, SPO2, galvanic skin response, GSR, and inertial measurement; a controller to control the operation of the stimulus generator and the applicator , the controller including a stimulus controller module to control the applied stimulation in accordance with a stimulation profile, the stimulation profile defining the applied stimulus in terms of duration and/or frequency and/or intensity/amplitude and/or width, wherein the stimulus controller module applies a stimulation profile based on the physiological parameters received from the at least one user biometric measuring sensor , so as to define a closed-loop feedback arrangement, wherein the stimulus controller module compares the received physiological parameters to a predetermined level or profile, and either selects an alternative stimulation profile or adjusts the existing stimulation profile being used, characterised in that the system includes: a training computer running an interactive computer cognitive training application, which the user is arranged to interact with, the training computer comprising a training processing module , which is arranged to be in communication with the nerve stimulator , to coordinate the stimulation of the median and/or ulnar nerves with particular activities or learning elements that the user must engage with, and/or at predetermined times during the training. a stimulus generator to generate at least one stimulus; an applicator to apply the generated stimulus to the arm, wrist or hand of the user , the applicator comprising at least one stimulus interface to apply the stimulus to the user's skin, proximate to the anterior or ventral side of the user's arm, wrist or hand; and at least one user biometric measuring sensor , embodied in or proximate the applicator , to monitor and determine physiological parameters associated with the user , including any one or more of the following: heart rate, HR, heart rate variability, HRV, temperature, SPO2, galvanic skin response, GSR, and inertial measurement; a controller to control the operation of the stimulus generator and the applicator , the controller including a stimulus controller module to control the applied stimulation in accordance with a stimulation profile, the stimulation profile defining the applied stimulus in terms of duration and/or frequency and/or intensity/amplitude and/or width, wherein the stimulus controller module applies a stimulation profile based on the physiological parameters received from the at least one user biometric measuring sensor , so as to define a closed-loop feedback arrangement, wherein the stimulus controller module compares the received physiological parameters to a predetermined level or profile, and either selects an alternative stimulation profile or adjusts the existing stimulation profile being used, <EOS>