Neurostimulation responsive to posture

An implantable device for controllably applying a neural stimulus, the implantable device comprising:

• a stimulus source for providing a stimulus to be delivered from one or more stimulus electrodes of a plurality of implanted electrodes to a neural pathway, the stimulus configured to evoke a neural compound action potential response on the neural pathway;
• measurement circuitry for recording a neural compound action potential signal sensed at one or more sense electrodes of the plurality of implanted electrodes;
• and
• a control unit configured to:
• control application of a neural stimulus as defined by a stimulus parameter;
• measure via the measurement circuitry a neural compound action potential response evoked by the stimulus;
• determine from the measured evoked response a feedback variable;
• implement a feedback controller which completes a feedback loop, the feedback controller using the feedback variable to control the stimulus parameter;
• and
• the control unit further configured to compile a multidimensional dataset comprising a plurality of data variable values, each data variable value being associated with a respective neural stimulus and associated measured evoked response, the multidimensional dataset comprising at least one of the stimulus parameter and the feedback variable;
• and
• the control unit further configured to store a plurality of multidimensional datasets over time in respect of a plurality of neural stimuli and respective associated measured evoked responses, by updating a multidimensional histogram to reflect each multidimensional dataset after it is obtained, and storing the multidimensional histogram in a storage unit of the implantable device.