Notes

The limbic structures are concerned with the affective nature of sensory sensations - that is, whether the sensations are pleasant or unpleasant or also called reward or punishment or satisfaction or aversion. (It is an important aspect, the hippocampus is associated with memory, indeed a strong way of remembering is by associating emotions to memories).

Reward Centers

• The major reward centers are located along the course of the media forebrain bundle (series of fibers that run along the C-Shape and connect the areas together), especially in the lateral and ventromedial nuclei of the hypothalamus.
• Weaker stimuli give a sense of reward, and stronger ones a sense of punishment.
• Less potent reward centers -- septum, amygdala, certain areas of the thalamus and basal ganglia.
• Stimulation of these areas gives a sense of reward. When offered the choice of eating some delectable food, the animal often chooses the electrical stimulation.

Punishment Centers

• Most potent areas have been found in the central gray area surrounding the Aqueduct of Sylvius in the mesencephalon.
• Less potent punishment areas are found in the amygdala and hippocampus.
• Stimulation in these areas causes the animal to show all sign of displeasure, fear, terror, pain and even sickness.

Rage - Its Association with Punishment Centers Strong stimulation of the punishment centers, especially in the periventricular zone of the hypothalamus and the lateral hypothalamus causes the animal to:

• Develop a defense posture
• Extend its claws
• Lifts its tail
• Hiss
• Spit
• Growl
• Develop piloerection, wide-open eyes and dilated pupils

(All these body manifestations are carried out by the Sympathetic Nervous System). Placidity and Tameness, exactly the opposite emotional behaviour patterns occur when the reward centers are stimulated.

Importance of Reward or Punishment in Behaviour Almost everything that we do is related to reward and punishment. If we are doing something rewarding, we continue to do it; if it is punishing we cease to do it. Reward and punishment centers constitute one of the most important of all the controllers of our bodily activities, our drives, our aversions, our motivations.

Importance of Reward or Punishment in Learning and Memory - Habituation vs Reinforcement

• If the sensory experience does not elicit a sense of either reward or punishment, repetition of the stimulus over and over leads to almost complete extinction of the cerebral cortical response, thus the animal becomes habituated to that specific sensory stimulus and thereafter ignores it.
• If the stimulus does cause either reward or punishment, the cerebral cortical response becomes progressively more and more intense during repeated stimulation and the response is said to be reinforced.