When dealing with fear, the hippocampus receives impulses from the amygdala that allow it to connect the fear with a certain sense, such as a smell or sound. Amygdala
The amygdala is an almond-shaped mass of nuclei located deep in the brains medial temporal lobe. It processes the events associated with fear and is linked to social phobia and other anxiety disorders. The amygdalas ability to respond to fearful stimuli occurs through fear conditioning. Like classical conditioning, the amygdala learns to associate a conditioned stimulus with a negative or avoidant stimulus, creating a conditioned fear response often seen in phobic individuals. The amygdala is responsible for recognizing certain stimuli or cues as dangerous and plays a role in the storage of threatening stimuli to memory. The basolateral nuclei (or basolateral amygdala) and the hippocampus interact with the amygdala in-memory storage. This connection suggests why memories are often remembered more vividly if they have emotional significance.In addition to memory, the amygdala also triggers the secretion of hormones that affect fear and aggression. When the fear or aggression response is initiated, the amygdala releases hormones into the body to put the human body into an "alert" state, which prepares the individual to move, run, fight, etc. This defensive "alert" state and response are known as the fight-or-flight response.However, inside the brain, this stress response can be observed in the hypothalamic-pituitary-adrenal axis (HPA). This circuit incorporates the process of receiving stimuli, interpreting them, and releasing certain hormones into the bloodstream.
The gene is not present on Y chromosomes and in normal females resides on and functions to inactivate many of the genes located on its own maternal but not the fathers X chromosome. Turner syndrome females with (46,X,i(Xq) sSMC consisting of a partial X chromosome that does not contain the XIST gene express at least some of this sSMCs genetic material and therefore contain excesses of this material. In consequence, they have a more serious form of the Turner syndrome that ranges form moderately severe to extremely severe. The extremely severe cases have anencephaly (absence of a major portion of the brain, skull, and scalp), agenesis of the corpus callosum (lack of the thick tract of nerve fibers that connect the left and right cerebral hemispheres), and complex heart deformities. Individuals with Turner syndrome that have partial X chromosome containing(46,X,i(Xq) sSMCs that have the XIST gene do not express this sSMCs genetic material and do not have the more severe manifestations of the syndrome. Inheritance
In the majority of cases where monosomy occurs, the X chromosome comes from the mother. This may be due to a nondisjunction in the father. Meiotic errors that lead to the production of X with p arm deletions or abnormal Y chromosomes are also mostly found in the father. Isochromosome X or ring chromosome X on the other hand are formed equally often by both parents. Overall, the functional X chromosome usually comes from the mother.