ABSTRACT
Sensory stimuli also initiate and enhance behaviour either because of their intrinsic sensory characteristics, as with certain gustatory and olfactory stimuli that may facilitate ingestive behaviours, or because they have acquired biological significance through experience and thus have rewarding or punishing properties. From the accumulated experimental evidence, the hypothalamus and limbic forebrain structures have been implicated in motivated behaviours as well as in physiological regulations. A widely used research strategy has been to infuse drugs and other chemical compounds directly into the brain usually by means of chronic intracerebral cannula. The treatment of experimental techniques used for studying the neural substrates of motivated behaviours is also selective. Complex neural integrative mechanisms, involving a number of central nervous system structures, have evolved for the coordination of motor responses for adaptive and goal-directed behaviours. The central nervous system controls the behaviours or "actions" of the animal by integrating various sensory inputs and sending "command signals" to the motor system.
