It is important to stress that, even in humans, these primitive structures remain active, not only as alerting mechanisms, vital for survival, but in the maintenance of the sleep-awake cycle. Ventral Tegmental Area in the ventral tegmental area, located in the mesencephalic part of the brain stem, there is a compact group of dopamine-secreting neurons whose axons end in the nucleus accumbens (mesolimbic dopaminergic pathway). The spontaneous firing or the electrical stimulation of neurons belonging to that region produce pleasurable sensations, some of them similar to orgasm. Many people who, for a genetic error, have a reduction of D2 (dopamine) receptors in the accumbens nucleus, become, sooner or later, incapable to obtain gratification from the common pleasures of life. Thus, they seek atypical and noxious "pleasurable" alternatives, like alcoholism, cocaine addiction, impulsive gambling and compulsion for sweet add foods. Certain brainstem structures, like the nuclei of the cranial nerves, stimulated by impulses coming from the cortex and the striatum (a subcortical formation are responsible for the physiognomic : expressions of anger, joy, sadness, tenderness, etc. Septum The septal region lies anteriorly to the thalamus. Inside it, one finds the centers of orgasm (four for women and one for men). This area has been associated with different kinds of pleasant sensations, mainly those related to sexual experiences.
This negative feed-back mechanism can be so strong as to generate a situation of panic. As it will be seen later on, the knowledge of this phenomenon is very important, for clinical and therapeutic reasons. Cingulate gyrus It is located in the medial side of the brain between the cingulate sulcus and the corpus callosum (principal fiber bundle connecting the two cerebral hemispheres). There is still much to be learned about this gyrus, but it is already known that its frontal part coordinates smells and sights with pleasant memories of previous emotions. This region mom also participates in the emotional reaction to pain and in the regulation of aggressive behaviour. Wild animals, submitted to the ablation of the cingulate gyrus (cingulectomy become totally tamed. The cutting of a single bundle of this gyrus (cingulotomy) reduces pre-existent depression and anxiety levels, by interrupting neural communication across the papez's circuit. Brainstem The brainstem is the region responsible for the "emotional reactions (indeed, they are just reflex answers) of inferior vertebrates, like reptiles and amphibians. The involved structures are the reticular formation, and the locus coeruleus, a concentrated mass of nor-epinephrine secreting neurons.
However, the importance of these nuclei on the regulation of emotional behavior, is not due to the thalamus itself, but to the connections of these nuclei with other limbic system structures. The medial dorsal nucleus makes connections with cortical zones of the pre-frontal area and with the hypothalamus. The anterior nuclei connect with the mamillary bodies, and through them, via fornix, with the hippocampus and the cingulate gyrus, thus taking part in the papez's circuit. Hypothalamus This structure has ample connections with the other prosencephalic areas and the mesencephalus. Lesions of the hypothalamic nuclei interfere with several vegetative functions and some of the so-called motivated behaviors, like thermal regulation, sexuality, combativeness, hunger and thirst. The hypothalamus is also believed to play a role in emotion. Specifically, its lateral parts seem to be involved with pleasure and rage, while the median part is like to be involved with aversion, displeasure and a tendency to uncontrollable and loud laughing. However, in general terms, the hypothalamus has more to do with the expression (symptomatic manifestations) of emotions than with the genesis of the affective states. When the physical symptoms of emotion appear, the threat they pose returns, via hypothalamus, to the limbic centers and, thence, to the pre-frontal nuclei, increasing anxiety.
The Expression of the Emotions in Man and Animals - wikipedia
These connections make it possible for the amigdala to play its important role on the mediation and control of resume major affective activities like friendship, love and affection, on the expression of mood and, mainly, on fear, rage and aggression The amygdala, being the center for. When triggered, it gives rise to fear and anxiety which lead the animal into a stage of alertness, getting ready to flight or fight. Experimental destruction of both amygdalas (there are two of them, one in each hemisphere) tames the animal, which becomes sexually non-discriminative, deprived of affection and indifferent to danger. The electrical stimulus of these structures elicits crises of violent aggressivity. Humans with marked lesions of the amygdala, loose the affective meaning of the perception of an outside information, like the sight of a well known person.
The subject knows, exactly, who the person is, but is not capable to decide whether he likes or dislikes him (or her). Hippocampus Is particularly involved with memory phenomena, specially with the formation of long-term memory (the one that, sometimes, lasts forever). When both hippocampi (right and left) are destroyed, nothing can be retained in the memory. The subject quickly forgets any recently received message. The intact hippocampus allows the animal to compare the conditions of a present threat with similar past experiences, thus enabling it to choose the best option, in order to guarantee its own survival. Fornix and Parahippocampal gyrus Both are important connecting pathways of the limbic system. Thalamus and Hypothalamus Thalamus Lesion or stimulation of the medial dorsal and anterior nuclei of the thalamus are associated with changes in emotional reactivity.
Emotional expression was thought to be governed by the hypothalamus. The cingulate gyrus projects to the hippocampus, and the hippocampus projects to the hypothalamus by way of the bundle of axons called fornix. Hypothalamic impulses reach the cortex via relay in the anterior thlamic nuclei. The essential error of the cannon-Bard theory was to consider the existence of an initial "center" for emotions (the thalamus). Soon enough, though, in 1937, the neuroanatomist James Papez would demonstrate that emotion is not a function of any specific brain center but of a circuit that involves four basic structures, interconnected through several nervous bundles : the hypothalamus with its mamillary bodies, the anterior.
This circuit (Papez circuit acting in an harmonic fashion, is responsible for the central functions of emotion (affect as well as for its peripheral expressions (symptoms). More recently, paul McLean, accepting the essential bases of Papez proposal, created the denomination limbic system and added new structures to circuit : the orbitofrontal and medialfrontal cortices (prefrontal area the parahippocampal gyrus and important subcortical groupings like the amygdala, the medial thalamic nucleus, the. The main Areas Involved with Emotions It is important to stress that all these structures interconnect intensively and none of them is the sole responsible for any specific emotional state. However, some contribute more than others to this or that kind of emotion. We shall review now, one by one, the best known structures of the limbic system. Amygdala and Hippocampus Amygdala a little almond shaped structure, deep inside the antero-inferior region of the temporal lobe, connects with the hippocampus, the septal nuclei, the prefrontal area and the medial dorsal nucleus of the thalamus.
Lost Garden: Shadow Emotions and Primary Emotions
It is precisely the acknowledgment of these symptoms (by the brain) that creates emotion. Stating it in a different way, we could say that physical sensations are the emotion. In 1929, walter Cannon refuted James's theory and advanced another one, that was soon modified by Phillip Bardand and became known as the cannon-Bard theory which states that, when a person faces an event that somehow affects him or her, the nervous paperless impulse travels straight. One part goes to the cortex to originate advantages subjective experiences like fear, rage, sadness, joy, etc. The other part goes to the hypothalamus to determine the peripheral neurovegetative changes (symptoms). According to this theory physiological reactions and emotional experience occur simultaneously. Papez believed that the experience of emotion was primarily determined by the cingulate cortex and, secondly, by other cortical areas.
And, when the superior mammals arrived on the earth, the third cerebral unit was finally developed : the neopallium or rational brain, a highly complex net of neural cells capable of producing a symbolic language, thus enabling man to exercise skillful intellectual tasks such. The neopallium is the great generator of ideas or, as expressed by paul MacLean, "it is the mother of invention and the father of abstractive thought". Theories on the role of Brain Structures in the formation of Emotions Comparison of the james-Lange and Cannon-Bard theories of emotion. According to the james-Lange theory (red arrows the man perceives the frightening animal and reacts with physical (neurovegetative) manifestations. As a consequence of such unpleasant physical reaction, he develops fear. In the cannon-Bard theory (blue arrows the frightening stimulus leads, first, to the feeling of fear stationery which, then, brings about the physical response. At the end of the last century, william James proposed that a person, after perceiving a stimulus that somehow affected him or her, endures disturbing physiological changes such as palpitations, shortness of breath, anxiety, etc.
of the olfactory bulbs and their connections made possible an accurate analysis of olfactory stimuli and the improvement of answers oriented by odors, such as approach, attack, flight and mating. Throughout evolution, some of these reptilian functions were lost or minimized (in humans, the amygdala and the entorhinal cortex are the only limbic structures that connect with the olfactory system). It is also in the r-complex that started the first manifestations of the phenomena of ritualism, by means of which the animal tries to define its hierarchic position inside the group and to establish its own space in the ecological niche In 1878, the French. The entirety of these structures, that, years later would receive the name of "limbic system developed with the emergence of the inferior ( primitive) mammals. This system commands certain behaviors that are necessary for the survival of all mammals. It gives rise and modulates specific functions that allow the animal to distinguish between the agreeable and the disagreeable. Here specific affective functions are developed, such as the one that induces the females to nurse and protect their toddlers, or the one which induces these animals to develop ludic behaviors (playful moods). Emotions and feelings, like wrath, fright, passion, love, hate, joy and sadness, are mammalian inventions, originated in the limbic system. This system is also responsible for some aspects of personal identity and for important functions related to memory.
It corresponds to the brain of the inferior mammals. 3 - the neopallium, also known as the superior or rational (new mammalian) homework brain, comprises almost the whole of the hemispheres (made up of a more recent type of cortex, called neocortex) and some subcortical neuronal groups. It corresponds to the brain of the superior mammals, thus including the primates and, consequently, the human species. These three cerebral layers appeared, one after the other, during the development of the embryo and the fetus (ontogenesis recapitulating, chronologically, the evolution of animal species (phylogenesis from the lizards up to the homo sapiens. According to maclean, they are three biological computers which, although interconnected, retained, each one, "their peculiar types of intelligence, subjectivity, sense of time and space, memory, mobility and other less specific functions". Actually, we have three cerebral units in a single brain. The primitive one is responsible for self preservation. It is there that the mechanisms of aggression and repetitive behavior are developed.
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Limbic System: The center of Emotions. Limbic, system: The center of Emotions, júlio rocha. Amaral, md jorge martins de Oliveira, md, phD. This, neurobiology article on, the limbic System is brought to you by, the healing Center On-Line. Introduction: The Three units of the human Brain. The neocortex, the Primitive brain, throughout its evolution, the human brain has acquired three components that progressively appeared and became superimposed, just like in an archeological site: the oldest, located underneath and to the back; the next one, resting on an intermediate position and the. They are, respectively: 1 - the archipallium or primitive review (reptilian) brain, comprising the structures of the brain stem - medulla, pons, cerebellum, mesencephalon, the oldest basal nuclei - the globus pallidus and the olfactory bulbs. It corresponds to the reptile brain, also called "R-complex by the famous neuroscientist paul MacLean. 2 - the paleopallium or intermediate (old mammalian) brain, comprising the structures of the limbic system.