SUMMARYThe cognitive and perceptual performance of 22 Parkinsonians was assessed as a function of unilateral cryosurgical lesion placement in relation to the ventrolateral area of the thalamus. Overt verbal and visual-spatial functions are not differentially affected by antero-posterior, niedial-lateral, and depth aspects of surgical lesion location with one exception. Preoperative t,o follow-up data revealed decrements on the Minnesota Form Board with deep lesion location. COOPER, I. S. Cryogenic surgery in the geriatric patient. J. Amer. Geriat. Soc., 1964, 7 , 813-855. RIKLAN, M., DILLER, L. and WEINER, H. Psychological studies on effects of chemosurgery of the basal ganglia in Parkinsonism: Intellectual functioning. Amer. med. Assn. Arch. gen. Psychiat., RIKLAN, M., DILLER, L. and WEINER, H. Psychological studies on the effects of chemosurgery of the basal ganglia in Parkinsonism: Aspects of personality. Amer. med. Assn. Arch. gen. Psychiat., RIKLAN, M. and DILLER, L. Visual motor performance before and after chemosurgery of the basal ganglia in Parkinsonism. J . new. ment. a s . , 1961, 132, 307-314. SIEGEL, S. Nonparamefric slatisliesfor the behavioral sciences.