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Ch 6.docx

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Department
Psychology
Course
PSY100H1
Professor
Hilscher
Semester
Fall

Description
Ch.6  Human brain has 100 billion neurons, 10 thousand-150 thousand synapses  Neuroimaging –machine monitors biochemical events in a series of conceptual slices through persons brain while comp takes info and constructs visual images of the brain showing which regions have been metabolically most active. –non invasive, PET, fMRI-movie pictures constructed to show brain active changing over time showing diff emotional states  Anatomy, lesions, stimulation, pharmacology (drugs), electrical recording  Hindbrain-control basic physiological processes o Medulla-regulates cardiovascular activity o Pons-control human sleep o Cerebellum-control motor movement  Forebrain-includes thalamus (integrates sensory info), hippocampus (memory), hypothalamus (eat,sex behavior,aggression, body temp), limbic system (emotion-amygdala, and cortex which sets human brain apart from other species)  Frontal lobes of cortex-planning and intentional action, emotion regulation  Descartes proposed that sensory stimuli pulled little strings that ran inside the sensory nerves to open valves which would let fluids from a central reservoir in the brain run down tubes (motor nerves) to inflate muscles-human reflex-we now know nerve messages carried electrical and chemically  Cannon,Bard-cats deprived of their cortex made sudden, inappropriate, ill directed attacks (sham rage). If fed and carefully taken care of, cats live longer with few spontaneous movement except this angry sham rage  Cannon proposed that the cortex usually inhibits this expression  Hess found that the elicited angry behavior came from the hypothalamus and not the thalamus like cannon said  Hughlings-Jackson=lower levels of brain (hindbrain) are reflex pathways related to simple functions like posture and movement. Next level has more recently evolved structures like emotions. Highest most recent evolved level, the cortex controls all levels below it. o Children abound with uncontrolled emotion until their cortex develops sufficiently to inhibit their lower functions  Papez-sensory impulses from body and outside world reach the thalamus and split 3 ways.- striatal region(movement), neocortex (thought) , limbic system-many connections to hypothalamus (feeling)  MacLean-human forebrain has 3 distinct systems, each developed in distinct phase of vertebrate evolution. Apart from the hypothalamus, the earliest basic part of forebrain is striatal region (scheduling and generating basic behaviors:prepare and establish home, forage, hunting,greeting,groom,mating,migration). When striatal region damaged (huntingdons’s chorea) ppl unable to organize daily activities-sit and do nothing,partake in activities planned for them  Reptiles lives alone, mammals born in close association with another –social creatures  Limbic system has close connections with hypothalamus, which not only controls the autonomic nervous system but via the pituitary gland, which is an extension of it, controls the bodys hormonal system.-limbic evolved for sociality  Amygdala-fear, stimulation of septal regions of limbic system induces a tendency to approach- self stimulation (pleasure center for food),-different areas for approach (encouragement) and withdrawal (avoidance)  Epilepsy-nerve cells in brain region fire together in self sustaining pattern-spreads to larger area. In temporal brain epilepsy (which can be caused by brain damage, virus, etc) discharges are contained within the limbic region, which implies the region in physiologically separate. Epileptic attacks in this area are preceded by auras, subjective states that often include strong emotions o Feelings are free floating, unattached to any particular thing, situation. Include desire, fear, anger, dejection (sad), gratulant feelings (happy, insight,achievement), and feelings of affection  Maclean-Panksepp conjecture=experience of emotion is generated in the limbic system, and that each distinct emotion type is based on a particular system of limbic brain circuitry. For each emotion, its circuitry creates a readiness for a set of species-characteristic brain processes and behaviors, somewhat appropriate to the event that triggered them. It is in these processes that the experience of a particular emotion arises-which we share with other animals-these are the original forms of consciousness  Using PET, brain regions where activation increased when ppl relived specific emotions were mostly sub-cortical in limbic system. Neural activity in the cortex decreased when emotions were experienced.  Ledoux-amygdala is the central emotional computer for the brain: it is the appraisal mechanism for emotions. It receives inputs from regions of the cortex concerned with visual recognition of objects and from regions concerned with recognizing sounds. Also has close connections with hypothalamus (emotion). Rewarding self-stimulation can be demonstrated in the amygdala and componenets of emotional behavior and autonomic responses can be elicited by electrical stimulation in this region. Also receives visual and auditory inputs directly via thalamus-not via routes that result in recognition of objects  Emotional conditioning for negative stimuli is quickly learned but slow to extinguish-why anxiety can be such a severe and long lasting clinical disorder  Ledoux-with conditioned stimuli of simple auditory tones or flashing lights, and with an unconditioned stimulus of electric shock to feet, rats will learn an association so long as the amygala and thalamus present-occurs even if cortex is removed (amygdale can receive sensory info that hasn’t been processed by cortex)  Amygala is site of primary appraisal-automatic evaluation of events in relation to goals and concerns, assigns emotional significance to events that signal dangers and threats  Perception of sad faces activates left amygdale and right temperol lobe. Fear activates left amygdale – unfamiliar faces can be threatening (amygala activation high for whites looking at black faces and vice versa)  Depressives suffering from bipolar disorder have enlarged amygdalas  Amygdale activation able to predict whether ppl will recall emotionally evocative stimuli o Memory for the negative slides were correlated with activation in the amygdale and the insula  Amydala not involved in the experience of emotions-damage didn’t impair patients expression of emotions  After the emergence of the striatum and limbic system comes the neocortex-distinct for higher mammals-80 % of whole human brain  Frontal lobes have close connections with the limbic system which play important role in emotion regulation  Scientists have assumed that the cortex inhibits more “primitive” behaviors served by lower regions  Prefrontal cortex includes: orbitofrontal region (representation of goals, rewards, approach and withdrawal tendencies), dorsolateral prefrontal region and the anterior cingulated and medial frontal regions.  2 kinds of evidence suggest that prefrontal cortex is important to regulation of emotion o Patients with damaged orbitofrontal cortex who have normal language, memory have problems showing emotional reactions that are appropriate to the social context. Inappropriate self conscious emotion o Imaging studies show regions of prefrontal cortex are activated when ppl try to inhibit emotional responses to evocative stimuli  When person has stroke on left side, they become paralyzed on ride side of body (loss of language)-no loss of language on left side but damage on right cortex impairs recognition of emotion in others  Right side of cortex associated with processing of emotional events –right brain superiority  Ppl with damage to left cortex better then ppl with right cortex damage and normal ppl in detecting if pp
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