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PSYC 2230
Pauline Charlton

CHAPTER 3: THE MOTIVATED AND EMOTIONAL BRAIN o The hunger-causing culprit is probably ghrelin, a hormone manufactured in the stomach, circulated in the blood, and detected and monitored by the brain o In a psych experiment those injected with ghrelin pig-out at an all you can eat buffet vs. those who werent who just ate a regular meal o In a study, researchers monitored naturally occurring ghrelin levels in adults, and then after some of the adults performed a 3-month diet with rigorous exercise o The results: First, Ghrelin was chronically high for the dieters Second, ghrelin rises and falls throughout the normal day (peaking around breakfast, lunch, etc.) Third, eating food led to a rapid fall in ghrelin Fourth, the lowest level of ghrelin after the diet equalled the highest level of ghrelin before the diet, which means that least hunger felt by dieters equalled the most hunger felt by non-dieters o the message is that diet induced food deprivation leads the body to generate a potent counterforce against further dieting and food deprivation (i.e. spike in ghrelin) o the body also has a hunger-suppressing hormones adipose (fat) tissue creates and releases leptin into the blood to stimulate brain activity underlying satiety THE MOTIVATED AND EMOTIONAL BRAIN o as the brain performs its functions, it cares not only about what task it is doing (using its cognitive-intellectual functions), but it also very much cares about whether you want to do it (motivated brain) and what your mood is while doing it (emotional brain) o when it comes to motivation and emotions the brain is the star, but theres a long list of supporting actors, including the major organs (e.g. brain, liver) and all the biochemical agents throughout the body (e.g. hormones) and central nervous system (e.g. neurotransmitters) Three Principles o to understand brain-based motivational processes, motivational researchers spend a great amount of time: 1. mapping out which brain structures are associated with which specific motivational states 2. investigating how the brain structures that are associated with motivational states become activated 3. understanding how day-to-day events in peoples lives create this activation process Specific Brain Structures Generate Specific Motivations o different brain structures, when stimulated, give rise to specific motivational states o damage to a particular brain structure takes away the persons capacity to experience specific motivational states o stimulation or damage to an integrated neural circuit (interconnected brain structures), or neurotransmitter pathway, or a single neurotransmitter can increase or decrease specific motivational states Biochemical Agents Stimulate Specific Brain Structures o brain structures have receptor sites on them that endow them with the potential to be stimulated o the biochemical agents that stimulate these receptor sites are neurotransmitters and hormones neurotransmitters are the communicatIon messengers of the nervous system (allowing one neuron to communicate with another), while hormones are the communication messengers of the endocrine system (allowing glands to communicate through the blood stream with bodily organs like the heart or lungs) Day-to Day Events Stir Biochemical Agents into Action o to carry out their research studies, surgeons and motivation researchers artificially stimulate brain structures and artificially release biochemical agents into the bloodstream and nervous system thus isolating the function of specific brain structures o the body reacts and adapts to day-to-day changes (e.g. hunger) manufacturing, releasing, and monitoring biochemical agents, such as hormones and neurotransmitters these biochemical agents stimulate the brain and generate the psychological experiences of specific motivational and emotional states Example: Environmental event: food deprivation (i.e. dieting) Biochemical Agent: ghrelin (hormone) produced and circulated in the blood stream Brain Structure: ghrelin stimulates hypothalamus Aroused Motivation: stimulated hypothalamus creates the psychological experience of hunger LOOKING INSIDE THE BRAIN o two ways to look inside a brain 1) surgery 2) functional magnetic resonance imaging: o 1) doctors surgically saw into a persons brain (persons awake!) then they can touch the surface of your cortex with a tiny, thin probe that emits an extremely mild electrical current the surgeon stimulates your brain, and your body automatically moves surgeons now can insert a tiny camera into the nostril or into an incision behind the ear and take a look via a remote computer screen the cerebral cortex and its functions (thinking, planning, remembering, etc) are intrinsically involved in generating and regulating motivation and emotional states (e.g. setting a goal, valuing an activity) specifically the limbic system is the part of the brain that is intricately involved in motivation and emotion o 2) the current gold standard for looking inside a persons brain is fMRIs the machine takes a detailed snapshot (electrical photograph) of the persons brain while they lie down on the machine as the person experiences a motivational and emotional state, the machine detects changes in blood oxygenation caused by brain activity over time the fMRI produces a videotaped version of moment-to-moment brain activity during a motivational or emotional episode o key brain structures involved in motivation and emotion: limbic system: structures include the hypothalamus, amygdala, hippocampus, septal area, ventral tegmental area, and the fibres that connect these structures into a communication network cerebral cortex: also associated with motivational and emotional states, as thinking itself can be an inherently motivation-emotion generating thing to do (e.g. setting a goal) o one way researchers can know which particular brain sites are associated with which particular motivational and emotional states can be determined by reviewing an fMRI as the persons motivation and emotion change, so would the activity in their brain the fMRI can pick up those changing brain states to confirm that this what the brain does during hunger, fear or during anticipation of a positive event, etc BRAIN-GENERATED APPROACH VS AVOIDANCE o table 3.1 organizes the key motivational and emotional brains structures associated with generating approach and avoidance o section below highlights the key motivational and emotional role played by 1. three approach-oriented structures: hypothalamus, medial forebrain bundle, and orbitofrontal cortex 2. two avoidance-oriented structures: amygdala, and hippocampus 3. the prefrontal cerebral cortex: which is associated with both approach and avoidance motivation 4. one arousal-associated structure reticular formation Hypothalamus o hypothalamus is a small brain structure that comprises less that 1% of the total volume of the brain o it exists as a collection of 20 neighbouring and interconnected nuclei that serve separate and discrete functions through the stimulation of its 20 separate nuclei, the hypothalamus regulates a range of important biological functions, including eating, drinking and mating (via the motivations for hunger satiety, thirst and sex) o by regulating the endocrine system and autonomic nervous system, the hypothalamus is able to regulate the bodys internal environment (e.g. heart rate, hormone secretion) so to adapt optimally to the environment (e.g. cope with a stressor) ES: the hypothalamus is immediately north of the pituitary gland, and it reg
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