A dog's behavior might seem like it's something simple that can be taught. His brain is an incredibly complicated organ, though. Various parts of a dog's brain work together to conduct a symphony of neurological processes and chemical reactions to stimuli. Those processes create the resulting behavior.
The Limbic System
The limbic system is the most primitive part of the dog brain, and functions virtually the same in dogs as it does in humans. It is responsible for experiencing and expressing emotions, which can directly affect behavior. Parts of the limbic system include the amygdala, which generates fear and aggression, the hypothalamus, which is responsible for triggering hormone release and the hippocampus, which aids in memory. There is a direct link between the limbic system and the autonomic nervous system, which allows physical behaviors to be caused by emotions. For example, a dog's hunger and thirst centers are suppressed when he feels sad or depressed, which is why many dogs won't eat or drink while their owners are gone. There is a direct link between the emotion and the resulting behavior.
The hypothalamus is responsible for regulating the release of hormones and for producing appropriate behavioral responses based on both memory and instinct. The hypothalamus triggers behaviors needed for daily maintenance, such as eating, drinking and body heat regulation. It aids the dog in feeling emotions and understanding relationships between positive emotions and certain behaviors. For example, the activity in the hypothalamus can help your dog experience a positive emotion such as pride, happiness, enjoyment or affection, associate it with a particular behavior and decide it's worth doing again.
Where the limbic system is the dog's emotional center, the cerebral cortex is his thought center. It produces learning, memory, attention, perceptual awareness and problem-solving. When it comes to dog behavior, the cerebral cortex and the limbic system have an important relationship with each other. While one brain system is stimulated or in use, the others function is inhibited. What this means in terms of behavior is, if a dog is afraid or anxious, he probably will not be able to learn or think his way through a problem.
Dogs experience a wide range of emotions, which will directly affect how he reacts to various stimuli. When he is anxious, upset or afraid, he will not be responsive to training. Positive rewards for desired behaviors work the best, since they will stimulate the parts of the dog's brain that associates pleasurable emotions with those behaviors. Like people, each dog has a different tolerance for a particular stimulus, so what works for one dog may be inappropriate for another. Whether you are training your dog yourself or working with a professional pet trainer, make sure your methods are tailored specifically to suit your dog.