PREFRONTAL CORTEX AND MATURATION OF PREFRONTAL CORTEX

	PREFRONTAL CORTEX

The prefrontal cortex (P.F.C.) is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas. This brain region has been implicated in planning complex cognitive behavior, personality expression, decision making and moderating social behavior.  The basic activity of this brain region is considered to be orchestration of thoughts and actions in accordance with internal goals.  The most typical psychological term for functions carried out by the prefrontal cortex area is executive function. Executive function relates to abilities to differentiate among conflicting thoughts, determine good and bad, better and best, same and different, future consequences of current activities, working toward a defined goal, prediction of outcomes, expectation based on actions, and social "control" (the ability to suppress urges that, if not suppressed, could lead to socially unacceptable outcomes).  Many authors have indicated an integral link between a person's personality and the functions of the prefrontal cortex. 

There are three possible ways to define the prefrontal cortex:

• as the granular frontal cortex
• as the projection zone of the mediodorsal nucleus of the thalamus
• as that part of the frontal cortex whose electrical stimulation does not evoke movements

Etymology

The term "prefrontal" as describing a part of the brain appears to have been introduced by Richard Owen in 1868. For him, the prefrontal area was restricted to the anterior-most part of the frontal lobe (approximately corresponding to the frontal pole). It has been hypothesized that his choice of the term was based on the prefrontal bone present in most amphibians and reptiles.

Interconnections

The prefrontal cortex is highly interconnected with much of the brain, including extensive connections with other cortical regions, as well as subcortical areas. The dorsal prefrontal cortex is especially interconnected with brain regions involved with attention, cognition and action, while the ventral prefrontal cortex. 

interconnects with brain regions involved with emotion. The prefrontal cortex also receives inputs from the brainstem arousal systems, and its function is particularly dependent on its neurochemical environment. Thus, there is coordination between our state of arousal and our mental state.

Maturation of the Prefrontal Cortex

The prefrontal cortex, the part of the frontal lobes lying just behind the forehead, is often referred to as the “CEO of the brain.” This brain region is responsible for cognitive analysis and abstract thought, and the moderation of “correct” behavior in social situations. The prefrontal cortex takes in information from all of the senses and orchestrates thoughts and actions to achieve specific goal.

The prefrontal cortex is one of the last regions of the brain to reach maturation. This delay may help to explain why some adolescents act the way they do. The so-called “executive functions” of the human prefrontal cortex include:

• Focusing attention
• Organizing thoughts and problem solving
• Foreseeing and weighing possible consequences of behavior
• Considering the future and making predictions
• Forming strategies and planning
• Ability to balance short-term rewards with long term goals
• Shifting/adjusting behavior when situations change
• Impulse control and delaying gratification
• Modulation of intense emotions
• Inhibiting inappropriate behavior and initiating appropriate behavior
• Simultaneously considering multiple streams of information when faced with complex and challenging information

This brain region gives an individual the capacity to exercise “good judgment” when presented with difficult life situations. Brain research indicating that brain development is not complete until near the age of 25, refers specifically to the development of the prefrontal cortex.

THIS IS AN IMPORTANT TOPIC FOR YOU NEXT EXAM

CONECTORES LINGÜÍSTICO EN INGLÉS POR CATEGORÍAS

 2.1. Hablando sobre el presente, la actualidad

• Hoy en día: Nowadays
• Actualmente: Currently, at present, at the present time, now, these days, in this day and age

2.2. Hablando sobre el pasado

• Hace mucho tiempo: A long time ago
• Hace poco tiempo: Not long ago
• En tiempos pasados: In former times
• Antiguamente: Formerly
• En los viejos tiempos: In the old days

2.3. Dando un ejemplo o una razón adicional

• Además: in addition, what’s more, besides,  furthermore, moreover
• Además de esto: Besides this
• También: Also, besides
• Es más: Moreover
• Lo que es más: What’s more

2.4. Diciendo la verdad

• Para decir la verdad, para ser sincero: To tell the truth
• En realidad, a decir verdad: In fact
• Realmente, en realidad: Actually*

*NOTA: Actually no debe confundirse con “actualmente”. Para tal fin es más común utilizar los ejemplos del apartado 2.1.

2.5. Dando información en contra de las expectativas

• Sin embargo, no obstante: However, nevertheless, all the same, still
• Aún así: Even so
• A pesar de que, a pesar de todo: notwithstanding, all the same, still, regardless

2.6. Mostrando el lado positivo y negativo de un asunto

• Afortunadamente, por fortuna: Fortunately, happily
• Felizmente, alegremente: Happily
• Desafortunadamente, desgraciadamente: Unfortunately, sadly
• Tristemente: Sadly

 2.7. Aportando similitudes y diferencias

• Igualmente: Likewise
• Del mismo modo: In the same way, similarly
• Por otra parte, por otro lado: On the other hand, in contrast
• De todos modos: Anyway

2.8. Declarando que algo es cierto o probablemente cierto

• Obviamente, evidentemente: Obviously
• Indudablemente: Undoubtedly
• Seguramente: Surely
• Verdaderamente, en realidad, en efecto: Indeed
• Claramente, aparenetemente, al parecer: Apparently
• Posiblemente: Possibly

 2.9. Mostrando una conclusión, consecuencia o un resultado directo

• Por lo tanto, por consiguiente: Therefore
• Consecuentemente, por consiguiente: Consequently

The brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few invertebrates such as sponges, jellyfish, adult sea squirts and starfish do not have one, even if diffuse neural tissue is present. It is located in the head, usually close to the primary sensory organs for such senses as vision, hearing, balance, taste, and smell. The brain of a vertebrate is the most complex organ of its body. In a typical human the cerebral cortex (the largest part) is estimated to contain 15–33 billion neurons,[1] each connected by synapses to several thousand other neurons. These neurons communicate with one another by means of long protoplasmic fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells.


From a philosophical point of view, what makes the brain special in comparison to other organs is that it forms the physical structure that generates the mind. As Hippocrates put it: "Men ought to know that from nothing else but the brain come joys, delights, laughter and sports, and sorrows, grief’s, despondency, and lamentations." In the early part of psychology, the mind was thought to be separate from the brain. However, after early scientists conducted experiments it was determined that the mind was a component of a functioning brain that expressed certain behaviors based on the external environment and the development of the organism. The mechanisms by which brain activity gives rise to consciousness and thought have been very challenging to understand: despite rapid scientific progress, much about how the brain works remains a mystery. The operations of individual brain cells are now understood in considerable detail, but the way they cooperate in ensembles of millions has been very difficult to decipher. The most promising approaches treat the brain as a biological computer, very different in mechanism from electronic computers, but similar in the sense that it acquires information from the surrounding world, stores it, and processes it in a variety of ways.


The human brain is the center of the human nervous system. It has the same general structure as the brains of other mammals, but is larger than expected on the basis of body size among other primates. Estimates for the number of neurons (nerve cells) in the human brain range from 80 to 120 billion. Most of the expansion comes from the cerebral cortex, especially the frontal lobes, which are associated with executive functions such as self-control, planning, reasoning, and abstract thought. The portion of the cerebral cortex devoted to vision is also greatly enlarged in human beings, and several cortical areas play specific roles in language, a skill that is unique to humans.


Despite being protected by the thick bones of the skull, suspended in cerebrospinal fluid, and isolated from the bloodstream by the blood-brain barrier, the human brain is susceptible to many types of damage and disease. The most common forms of physical damage are closed head injuries such as a blow to the head, a stroke, or poisoning by a variety of chemicals that can act as neurotoxins. Infection of the brain, though serious, is rare due to the biological barriers which protect it. The human brain is also susceptible to degenerative disorders, such as Parkinson's disease, multiple sclerosis, and Alzheimer's disease. A number of psychiatric conditions, such as schizophrenia and depression, are thought to be associated with brain dysfunctions, although the nature of such brain anomalies is not well understood.


How many neurons does the brain have?


What are the axons?


Where is located the brain?


What was thought in the early psychology


What did Hippocrates say?


How is protected the brain?


What disorders does the article talk?

V I H

HIV

               Human immunodeficiency virus (HIV) is a lentivirus (a member of the retrovirus family) that causes acquired immunodeficiency syndrome (AIDS),^[1][2] a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive. Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. The four major routes of transmission are unsafe sex, contaminated needles, breast milk, and transmission from an infected mother to her baby at birth (perinatal transmission). Screening of blood products for HIV has largely eliminated transmission through blood transfusions or infected blood products in the developed world.

HIV infects vital cells in the human immune system such as helper T cells (specifically CD4⁺ T cells), macrophages, and dendritic cells.^[9] HIV infection leads to low levels of CD4⁺ T cells through three main mechanisms: First, direct viral killing of infected cells; second, increased rates of apoptosis in infected cells; and third, killing of infected CD4⁺ T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When CD4⁺ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections.

Signs and symptoms

A generalized graph of the relationship between HIV copies (viral load) and CD4 counts over the average course of untreated HIV infection; any particular individual's disease course may vary considerably.CD4⁺ T cell count (cells per µL)  HIV RNA copies per mL of plasma Infection with HIV-1 is associated with a progressive decrease of the CD4⁺ T cell count and an increase in viral load, the level of HIV in the blood. The stage of infection can be determined by measuring the patient's CD4⁺ T cell count and viral load.

The stages of HIV infection are acute infection (also known as primary infection), latency and AIDS. Acute infection lasts for several weeks and may include symptoms such as fever, lymphadenopathy (swollen lymph nodes), pharyngitis (sore throat), rash, myalgia (muscle pain), malaise, and mouth and esophageal sores. The latency stage involves few or no symptoms and can last anywhere from two weeks to twenty years or more, depending on the individual. AIDS, the final stage of HIV infection, is defined by low CD4+ T cell counts (fewer than 200 per microliter), various opportunistic infections, cancers and other conditions. AIDS When CD4⁺ T cell numbers decline below a critical level of 200 cells per µL, cell-mediated immunity is lost, and infections with a variety of opportunistic microbes appear. The first symptoms often include moderate and unexplained weight loss, recurring respiratory tract infections (such as sinusitis, bronchitis, otitis media, pharyngitis), prostatitis, skin rashes, and oral ulcerations.

Common opportunistic infections and tumors, most of which are normally controlled by robust CD4⁺ T cell-mediated immunity then start to affect the patient. Typically, resistance is lost early on to oral Candida species and to Mycobacterium tuberculosis, which leads to an increased susceptibility to oral candidiasis (thrush) and tuberculosis. Later, reactivation of latent herpes viruses may cause worsening recurrences of herpes simplex eruptions, shingles, Epstein-Barr virus-induced B-cell lymphomas, or Kaposi's sarcoma.

Pneumonia caused by the fungus Pneumocystis jirovecii is common and often fatal. In the final stages of AIDS, infection with cytomegalovirus (another herpes virus) or Mycobacterium avium complex is more prominent. Not all patients with AIDS get all these infections or tumors, and there are other tumors and infections that are less prominent but still significant.

Sexual

The majority of HIV infections are acquired through unprotected sexual relations. Complacency about HIV plays a key role in HIV risk.^[3][4] Sexual transmission can occur when infected sexual secretions of one partner come into contact with the genital, oral, or rectal mucous membranes of another. In high-income countries, the risk of female-to-male transmission is 0.04% per act and male-to-female transmission is 0.08% per act. For various reasons, these rates are 4 to 10 times higher in low-income countries.^[37] The rate for receptive anal intercourse is much higher, 1.7% per act.^[37]

Blood products

In general, if infected blood comes into contact with any open wound, HIV may be transmitted. This transmission route can account for infections in intravenous drug users, hemophiliacs, and recipients of blood transfusions (though most transfusions are checked for HIV in the developed world) and blood products. It is also of concern for persons receiving medical care in regions where there is prevalent substandard hygiene in the use of injection equipment, such as the reuse of needles in Third World countries. Health care workers such as nurses, laboratory workers, and doctors have also been infected, although this occurs more rarely. Since transmission of HIV by blood became known medical personnel are required to protect themselves from contact with blood by the use of universal precautions. People giving and receiving tattoos, piercings, and scarification procedures can also be at risk of infection. HIV has been found at low concentrations in the saliva, tears, and urine of infected individuals, but there are no recorded cases of infection by these secretions and the potential risk of transmission is negligible.^[58] It is not possible for mosquitoes to transmit HIV.^[59]

Mother-to-child

The transmission of the virus from the mother to the child can occur in utero (during pregnancy), intrapartum (at childbirth), or via breast feeding. In the absence of treatment, the transmission rate up to birth between the mother and child is around 25%.^[34] However, where combination antiretroviral drug treatment and Cesarian section are available, this risk can be reduced to as low as one percent.^[34] Postnatal mother-to-child transmission may be largely prevented by complete avoidance of breast feeding; however, this has significant associated morbidity. Exclusive breast feeding and the provision of extended antiretroviral prophylaxis to the infant are also efficacious in avoiding transmission.^[60] UNAIDS estimate that 430,000 children were infected worldwide in 2008 (19% of all new infections), primarily by this route, and that a further 65,000 infections were averted through the provision of antiretroviral prophylaxis to HIV-positive women.^[61]