investigation of the structure and functions of the brain, including, for example, (a) the administration of psychological and neurological tests after lesions have occurred in various areas; (b) the observation or measurement of the effects of stimulation or ablation of parts of the brain; (c) the use of gross and microscopic anatomical and histopathological techniques; (d) the study of the nature and functions of chemicals involved in neurotransmission; and (e) the use of electroencephalography and brain imaging techniques.