Effects of Certain Subcortical Lesions on Learning and Performance in the Cat

The role of the hypothalamus and thalamus in the maintenance of normal cortical states and normal patterns of behavior has been considerably investigated. The stimulation studies of Hess⁷ have demonstrated certain zones which appear to subserve native, unlearned types of behavioral states. Hunter and Jasper⁸ have likewise investigated behavioral and EEG responses in consequence of subcortical stimulation. The classical studies of the Magoun group 11,12 have delineated the upward passage of the reticular activating system and have indicated the importance of the hypothalamus in this system, as well as of certain thalamic nuclei. Both stimulation and ablation techniques have been employed by them. Ingram et al.⁹ have also investigated relationships between hypothalamus and cortex, by ablation and EEG studies; and Knott et al.¹⁰ by similar techniques, relationships between thalamic nuclei and cortex. Chow et al.⁶ have also investigated certain aspects of these problems. These studies