This project has been directed toward providing more understanding of how and what parts of the mesodiencephalon are most relevant to the conscious awareness of pain. The investigation has been involving neuronal areas and fiber tracts that largely participate in pain production via the older palespinothalamic system. Some of the many unsolved nociceptive problems are being approached for clarification using essentially the sequences of (1) behavioral-shaping by intracranial, tooth pulp (trigeminal) and radial peripheral nerve electrical stimulation, (2) neuropharmacological drugs, (3) electrolytic lesions of significant midbrain and thalamic areas to compare their effect on blocking nociceptive escape responses to that of analgesic drugs and/or non-nociceptive (auditory) avoidance behavior, and in chosen cases the tracing of degenerating axonal fibers. Also, when unanticipated responses or findings occur that may be relevant to the broad ramifications of behavior, such nuclear areas and fiber tracts are further investigated to determine if they are pertinent to the overall study. In addition, the work is aimed at maintaining as much relevance as possible to the problems confronted by the clinicians in human pain.