Physiologic anatomic

specific phobia

Physiologic anatomic

Emotions based motivational organization can be classified into two major groups: pleasant and unpleasant. The first pulses are associated appetitive, while the latter facing the defensive reactions.

Defensive reactions occur emotional and psycho physiological components, to be associated with negative emotions of anxiety and fear (Kanjorski, 1967; Stein, 2005).

Anxiety is generated by the participation of various brain structures. Of all these, the amygdale is one of the most important. A mass of gray matter (in the form of almond) which is located in the rostral pole temporal lobe. It is a major component of the limbic system. It comprises three cores, which are connected with other important parts of the brain. These are: corticomediales nuclei, basolateral nuclei and central nucleus (ACE).

The amygdale acts as an emotional processor. Participate actively in the experience and expression of emotions. It was found that the central nucleus and the lateral nucleus (a component of the basolateral nuclei), are involved in the acquisition of experience and the negative emotion of fear.

Sensory information (emotional stimulus) enters the amygdale through various channels that lead afferents to the lateral and basolateral nuclei. Once there, organize the components of emotional response that will projected through the core through various channels efferent, that this information will lead to the periaqueductal gray, the lateral hypothalamus, the Para ventricular hypothalamus and the dorsal motor nucleus vague and ambiguous nuclei. From each of them, pass information through their respective channels, which will result in four categories of emotional response of fear conditioning or learned. These are:

- Emotional behavior (eg stopping of homework).

- The sympathetic response (eg blood pressure increase).

- Hormonal response (eg release of cortical and adrenaline).

- Parasympathetic response (eg developing bradycardia).

For its part, the lateral nucleus of the amygdale have the capacity to process information in parallel from multiple channels of stimulation. Receive information from higher-order areas of the necrotic and hippocampus (slow cortical circuit), and from sensory processing areas of the necrotic and thalamus (sub cortical circuit fast). These two circuits help to make possible the acquisition of fear. It is also important to remember that the cortical circuit is involved in the formation of explicit memories.

Panicky et al., (1994) and Stein (2005), also indicate that the information output of the amygdale can be grouped into two main classes: the defensive action (fight-flight response), and immobility somatomotor (freezing).

It is also appreciated that when an unconditioned stimulus (ENC) is associated with a threat or paired (conditioned stimulus, CS), in future exposures to that stimulus will be an intense startle response, which will reflect the fear. This phenomenon is known as: fear potentate startle.

Other brain structures such as the hippocampus that is located within the temporal lobe, involved in defense responses, such as avoidance of stimuli feared. Also involved in memory and spatial orientation.

Likewise, it has been found that CRF or CRH (or releasing hormone corticotrophin releasing factor) is an abundant neuropeptide in the amygdale (Van Bookstall, Colugo and Valentino, 1998). This is released by neurons of the central core (ACE), and from here be projected towards the core of the bed. Thus when the activated tonsil, activates both long term and the core bed by the action of the hormone (CRH), causing an antigenic effect lasting (Skanska, Shibasaki, and Ledgers, 1986; Stein, 2005).

Moreover, the CRH also has a potentiating effect on the antigenic response (reflection) of startle in individuals. Also involved in the response to stressful stimuli.

Biological predisposition to acquire certain fears (evolutionarily prepared fears) in humans, together with the possibility of the hyper activation of tensile system (activation stimuli quickly to low power), and the differential activation of various pathways have facilitated the emergence efferent specific phobia, manifested as a neuronal circuit abnormal activation of fear.

There are many clinical investigations with its exploration data collected from their involvement in this type of fear circuit in specific phobia. The most compelling comes from studies using the technique of positron emission tomography (PET), which through their images (horizontal cuts), have been observed activation of neural circuits in the amygdale, striatum, and thalamus, as well as increased blood flow in the area of the limbic cortex Para limbic (Wick et al., 1996; Stein, 2005).

 SOCIAL ANXIETY DISORDER TEST