Thalamic theory of emotions

Main concept of Cannon and Bard

The thalamic theory, developed by researchers W. Cannon and P. Bard, fundamentally shifted the focus of attention in studying the nature of feelings. The main premise of their concept is that the genesis of emotions is inextricably linked to the functional activity of deep brain structures.

Instead of looking for the source of experiences exclusively on the periphery of the body or in the cerebral cortex, the authors suggested that subcortical nuclei are the central link of emotional response. It is there, according to them, that the mechanisms are triggered which we subjectively perceive as joy, fear, or anger.

Clinical evidence of the theory

Any physiological concept requires solid confirmation. For the thalamic theory, one of the most important pillars has been medical practice and patient observations.

Physicians noticed that when a pathological lesion is localized directly in the deep structures of the brain, patients develop pronounced disorders of the emotional sphere. Such pathologies include:

• Intracerebral tumors compressing subcortical centers.
• Hemorrhages in the thalamus and hypothalamus.

The spectrum of emerging disorders proved to be extremely broad. Depending on the exact location and extent of the damage, patients exhibited extreme states: from pathologically increased, uncontrolled irritability to the total suppression of any emotional manifestations (apathy).

Experimental data: R. Hess's experiments

The second fundamental base of evidence was gathered by neurophysiologist R. Hess, who conducted experiments on animals. His studies made it possible to observe the work of subcortical centers in real time.

Research methodology Hess used the method of chronic electrode implantation into the brains of animals (cats were used as subjects). The electrodes were targeted precisely at the structures of the thalamus and hypothalamus. This made it possible to stimulate specific nuclei with an electric current and observe the reaction of a free, conscious animal.

Stimulation results The impact on deep structures caused a whole cascade of diverse behavioral patterns. Depending on the stimulation point, the cats clearly exhibited the following reactions:

1. Feeding reactions (searching for food, chewing).
2. Aggressive reactions (hissing, unsheathing claws, attacking).
3. Defensive reactions (attempts to run away, hide).
4. Sexual reactions.

Interestingly, the genesis of all these reactions is closely intertwined with the work of limbic system structures, which act as the ultimate regulator of autonomic and emotional functions.

The phenomenon of sham emotions

The most important term introduced by R. Hess based on his experiments was the concept of sham emotions (Sham emotions).

Observing cats during hypothalamic stimulation, the researcher witnessed furious aggression or panic-like fear. However, after turning off the current, the animal instantly calmed down as if nothing had happened. Hess designated these violent reactions as "sham" because the researcher can only evaluate external, motor, and autonomic manifestations. At the same time, it is extremely difficult to reliably judge the presence of a real, deep subjective experience characteristic of true emotion based on the animal's behavior alone.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Anatomy and physiology of limbic system structures
• The connection of the hypothalamus with autonomic manifestations during aggressive and defensive reactions
• Mechanisms of feeding and sexual behavior formation
• Method of chronic electrode implantation: historical aspect
• The subjective component of emotions and the problem of its assessment in animal experiments

Other topics in the "Emotions" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.