We do not experience our brain as an assembly of physical structures nor would we wish to, perhaps ; if we envision it at all, we are likely to see it as a large, rounded walnut, grayish in color. This schematic image refers mainly to the cerebral cortex, the outermost layer that overlies most of the other brain structures like a fantastically wrinkled tissue wrapped around an orange. But underneath this layer reside many other specialized structures that are essential for movement, consciousness, sexuality, the action of our five senses, and more—all equally valuable to human existence. Indeed, in strictly biological terms, these structures can claim priority over the cerebral cortex.
Overview of Addiction Related Brain Regions The nucleus accumbens definitely plays a central role in the reward circuit. Its operation is based chiefly on two essential neurotransmitters: Many animal studies have shown that all drugs increase the production of dopamine in the nucleus accumbens, while reducing that of serotonin.
But the nucleus accumbens does not work in isolation. It maintains close relations with other centres involved in the mechanisms of pleasure, and in particular, with the ventral tegmental area VTA. Located in the midbrain, at the top of the brainstem, the VTA is one of the most primitive parts of the brain.
It is the neurons of the VTA that synthesize dopamine, which their axons then send to the nucleus accumbens. The VTA is also influenced by endorphins whose receptors are targeted by opiate drugs such as heroin and morphine. Another structure involved in pleasure mechanisms is the prefrontal cortex, whose role in planning and motivating action is well established.
The prefrontal cortex is a significant relay in the reward circuit and also is modulated by dopamine. The locus coeruleus, an alarm centre of the brain and packed with norepinephrine, is another brain structure that plays an important role in drug addiction.
When stimulated by a lack of the drug in question, the locus coeruleus drives the addict to do anything necessary to obtain a fix.
Two structures in the limbic system also play an active part in the pleasure circuit and, consequently, in drug dependency.
The first is the amygdala, which imparts agreeable or disagreeable affective colorations to perceptions. The second is the hippocampus, the foundation of memory, which preserves the agreeable memories associated with taking the drug and, by association, all of the details of the environment in which it is taken.
Sometime in the future, these details may reawaken the desire to take the drug and perhaps contribute to recidivism in the patient. The nucleus accumbens, the ventral olfactory tubercle, and ventral caudate and putamen collectively form the ventral striatum.
This nucleus is thought to play an important role in reward, pleasure, and addiction.
It is part of the ventral continuation of the dorsal striatum, and shares general principles of connectivity with the striatum. The nucleus accumbens is also called ventral striatum.
The principal neuronal cell type found in the nucleus accumbens is the medium spiny neuron. These neurons are also the main projection or output neurons of the nucleus accumbens. The output neurons of the nucleus accumbens send axon projections to the ventral analog of the globus pallidus, known as the ventral pallidum VP.
The VP, in turn, projects to the mediodorsal MD nucleus of the thalamus, which projects to the prefrontal cortex. Major inputs to the nucleus accumbens include the prefrontal cortex, amygdala, hippocampus, and dopaminergic neurons located in the ventral tegmental area VTAwhich connect via the mesolimbic pathway.
Thus the nucleus accumbens is often described as one part of a cortico-striato-thalamo-cortical loop. Dopaminergic input from the VTA is thought to modulate the activity of neurons within the nucleus accumbens.
These terminals are also the site of action of highly-addictive drugs such as cocaine and amphetamine, which cause a several-fold increase in dopamine levels in the nucleus accumbens. In addition to cocaine and amphetamine, almost every drug abused by humans has been shown to increase dopamine levels in the nucleus accumbens.
Although the nucleus accumbens has traditionally been studied for its role in addiction, it is plays an equal role in processing natural rewards such as food, sex, and video games. It is rich in dopamine and serotonin neurons, and is part of two major dopamine pathways: The ventral tegmentum is considered to be part of the pleasure system, or reward circuit, one of the major sources of incentive and behavioural motivation.
Activities that produce pleasure tend to activate the ventral tegmentum, and psychostimulant drugs such as cocaine directly target this area.
Hence, it is widely implicated in neurobiological theories of addiction. It is also shown to process various types of emotion and security motivation, where it may also play a role in avoidance and fear-conditioning. Prefrontal Cortex PFC is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.
Cytoarchitectonically, it is defined by the presence of an internal granular layer IV in contrast to the agranular premotor cortex.
Divided into the lateral, orbitofrontal and medial prefrontal areas, this brain region has been implicated in planning complex cognitive behaviors, personality expression and moderating correct 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 neurologic term for functions carried out by the pre-frontal cortex area is Executive Function. Executive Function relates to abilities to differentiate between 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 or illegal outcomes.
Many authors have indicated an integral link between a person's personality and the functions of the prefrontal cortex. Locus ceruleus LCalso spelled locus caeruleus or locus coeruleus Latin for 'the blue spot'is a nucleus in the brain stem responsible for physiological responses to stress and panic.
The locus ceruleus or "LC" resides on the dorsal wall of the upper pons, under the cerebellum in the caudal midbrain, surrounded by the fourth ventricle.Nov 21, · Subject MCAT Outline of Topics: Summary Difference in content between the old MCAT and the current MCAT format; MCAT Biology.
DNA, genetics, evolution, biotechnology, eukaryotic cell, prokaryotes vs. eukaryotes, viruses, reproductive system, embryology, nervous system, endocrine system, circulatory system, respiratory system, digestive system, immune system, lymphatic system, .
Book reviews and excerpts about brain anatomy, neurobiology of human behavior, innate behavior, OCD neurocircuitry, effects of stress, attachment theory, family systems theory, ethology, and epigentics. Harnessing Neuroplasticity: 9 Key Brain Regions Upgraded Through Meditation.
So, What Is Neuroplasticity? Blowing away decades of scientific dogma, the recently discovered "neuroplastic" nature of the brain means that our potential is not set at birth — we can actually strengthen and improve our brain in ways once believed r-bridal.coma Gladding M.D., author of "You Are Not Your Brain.
Scientists use gyri and sulci to divide the cerebral cortex into smaller units called lobes. Each hemisphere has four lobes. The occipital lobes, at the back of the brain, control vision. Jun 01, · Identifying the major regions of the brain and what functions of behavior the systems of each region control?Status: Resolved.
The outermost layer of the cerebral hemisphere which is composed of gray matter. Cortices are asymmetrical. Both hemispheres are able to analyze sensory data, .