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Phobias and the brain: Eliminating phobias


A phobia is an intense fear that appears immediately when faced with a specific object or situation. Most common phobias include fear of certain animals or insects, flying, heights, injections or blood. However, phobic situations and objects can vary greatly.

Fear should help protect us; with a phobia though, the fear is maladaptive and can become an obstacle in our daily routine. Phobias are learned just like any other fear and are accompanied by plastic changes in the brain that occur very quickly and are very resistant to extinction, as the body feels that its very survival would be at stake if the fear ceased.

The brain structure that plays a critical role in phobias is the amygdala that is commonly associated with emotions (especially fear). The amygdala is responsible for connecting the fear-arousing stimulus with theenvironmental contextin which it is occurring. In addition, the amygdala triggers responses from the body to react quickly to threat and danger.

How to tell if you have a phobia

According to the diagnostic criteria of the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the features of phobias are described below:

The origins of phobia. Brain-phobia connectivity

Fear and anxiety have a biological basis, that is, they are evolutionarily developed responses aimed at detecting or anticipating threats. Fear is accompanied by autonomic and endocrine changes that prepare the body to react to danger (e.g., fighting, fleeing, or freezing) with the aim of increasing chances of survival.

However, this fear can be maladaptive (as in the case of phobias) because, in addition to not contributing significantly to survival, it can create difficulties in our daily lives.

Organisms have innate fears, that is, they are born with these fears,they didn’t have to learn them through experience. Examples of innate fears are painful or very intense stimuli such as loud sounds. However, as individuals gain worldly experience, they become aware of the existence of aversive and dangerous situations. Little by little, they learn what they are and where they usually appear to avoid them or deal with them efficiently. This learned fear is still adaptive, but it can become maladaptive as in phobias and anxiety disorders.

Pavlovian conditioning

Pavlovian conditioning is one of the most commonly used models of fear learning: here, a neutral stimulus (e.g., a tone) is paired with an aversive event (e.g., an electric shock); the conditioned stimulus, which at first meant nothing, acquires an ability to elicit fear in the subject. This happens because the tone-shock pairing is quickly stored in memory, and the fear response is displayed as soon as the tone is heard.

Theory of biological preparedness

Fear conditioning is a powerful process that occurs very quickly. A single pairing of two such stimuli is sufficient to establish a memory.

According to Martin Seligman’s theory of biological preparedness, phobias result from a group of biological associations that the organism is evolutionarily prepared to learn quickly and persistently. Thus, conditioning to fear-relevant stimuli such as snakes, spiders, fearful or angry facial expressions and out-groupfaces are more resistant to extinction and can be consolidated without conscious awareness.

Once learned, conditioned fear responses can last a lifetime. However, fear responses may weaken or extinguish through experiences that show that the conditioned stimulus no longer predicts danger.

Neural basis

The entire process of acquiring phobias has a neural basis. The brain is plastic, that is, it changes based on habits and learning. During fear conditioning, neurons undergo molecular and structural changes.

In addition, there are also specific brain regions that are closely associated withfear and phobias. The region most relevant is the amygdala, whose role is described below.

Amygdala and phobias

The amygdala is typically associated with both adaptive and maladaptive fear. It is a small almond-like shape structure located deep in the brain that is part of the limbic system (system for emotion).

The amygdala is a complex structure consisting of several distinct groups of cells, interconnected and functionally diverse:

The lateral amygdala is the main site of synaptic changes under lying fear learning. Neural connections become strengthened as fear conditioning is established.

Interesting studies on phobias and brain activity

Animal studies have shown that if the central nucleus of the amygdala is stimulated, different parts of the fear response can be triggered. However, damage to this site decreases fear responses to conditioned stimuli. Furthermore, the person cannot acquirenew fears.

On the other hand, damage tothe hippocampus—an area that sends input to the amygdala regarding the location of the fear-arousing stimulus—onlyeliminates the contextual fear conditioningwithout affecting conditioned fear to the stimulus.

Regarding brain activity in phobias, a study by Schienleet al. (2005) found differences between individuals with spider phobia and those who did not suffer from spider phobia while viewing pictures of spiders and other pictures of neutral insects. Spider phobics showed greater activation of the amygdalae, the visual association cortex, the right hippocampus, and the right dorsolateral prefrontal cortex. This latter area appears to be associated with the processing of negative emotions. Activation was also observed in the supplementary motor area (which is involved in movement preparation and motivation). In addition, spider phobic individuals showed greater amygdala activation than control subjects while viewing the disgust-inducing pictures.

A meta-analysis published in 2012 showed hyperactivation in the insula (as well as in the amygdala) of phobic individuals. Both structures are associated with negative emotional responses.

Eliminating phobias

How to make phobias disappear? Phobias may be eliminated by repeated exposure to the fear-arousing stimulus in a neutral or safe context. Little by little, the person learns that the phobic object or event is no longer dangerous. This phenomenonforms a basis of effective exposure therapies.

There is neural basis for all this too, since studies have revealed that interactions between the amygdala, the hippocampus and the medial prefrontal cortex regulate the extinction of fear.


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