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Lecture 8

PSYCH 309 - Lecture 8 (Self Representation) - Oct 1.docx

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PSYC 309
Todd Handy

October 1, 2013 – Lecture 8 Readings: Out of Body Experiene? Your Brain Is to Blame – Blakeslee • E.g. feels shadowy figure standing behind; feels herself leaving her body and floating in space • Neuroscientists: induced by delivering mild electric current to specific spots in the brain o Angular gyrus – part of temporal parietal junction; sensation that she was hanging from ceiling; another felt someone was behind her, intent on interfering with her actions  Blends vision with body sense • Epilepsy surgery – doctors implanted dozens of electrodes into brains to pinpoint abnormal tissue causing seizures; identify adjacent areas involved in language, hearing, essential functions o Patient asked what she was experiencing • Peter Brugger – neuroscientist, expert on phantom limbs o Self can be detached from body, can live a phantom existence on its own, as in an out-of-body experience, or it can be felt outside of personal space, as in a sense of presence • Researchers: discovered some areas of the brain combine information from several senses. o Vision, hearing, touch – processed in primary sensory regions; flow together, create wholeness of a person’s perceptions • Dr. Olaf Blanke – carried out procedures o Women had normal psychiatric histories, stunned by bizarre nature of experiences • Multisensory processing regions build up perceptions of the body as it moves through the world o Skin – sensors provide information about pressure, pain, heat, cold o Joints, tendons, bones – where the body is positioned in space o Ears – sensors track sense of balance o Internal organs (heart, liver, intestines) – emotional state • Real-time info from body, space around body, subjective feelings from body – represented in multisensory regions (Blanke) o Regions simulated by electric current – integrity of sense of body can be altered • 22 yr old – electrodes implanted into left side of brain o Turned head to the right – Checking language areas; electrode nowhere near areas involved in control of movement; current stimulating multisensory area (angular gyrus) o Weird sensation that another person was lying beneath her on the bed o Felt like a shadow that did not speak or move; wanted to interfere with her o Blanke turned off current – woman stopped looking to right, strange presence gone • Presence closely mimicked patient’s body posture and position o Unusual perception of her own body, as a double o Shadowy presence – without electrical stimulation; sensory deprivation, minor strokes, disruption in blood flow to brain • Out of body experience – “I am at the ceiling looking down at my legs” o Woman’s felt position in space and actual position did not match o Schizophrenics – paranoid delusions, sense someone is following them • Normal people – sensation so seamless, familiar, don’t realize it is creation of the brain o Brain’s attempt to make explanation and sense of conflicting information (interpretation), mind turn confusion into coherent experience Illusory own body perceptions: Case reports and relevance for bodily self-consciousness – Heydrich • Neurological disorders of body representation have for a long time suggested the importance of visual and multisensory processing of bodily signals for self- consciousness: o Self location – “where I experience to be” o First person perspective – directedness of conscious experience “where I experience to perceive the world from” o Self identification – humans identify with their body – “what I experience as my body” • Two neurological patients with paroxysmal disorders of full body representation – only self-identification was abnormal; involving predominantly the trunk and head • Contributions of bodily processing and body representation to self consciousness o Multisensory and sensorimotor aspects of self-consciousness • Historically – clinical reports of neurological and psychiatric patients suffering from disorders of body representation and illusory own body perceptions – close links between bodily processing and self-consciousness o Highlight importance of multisensory bodily processing in patients suffering migraines • Disorders of body representation o Absence of body part o Body part transformations o Body part displacement o Disconnection of one body part from body o Delusional misidentification of one’s own body part (somatoparaphrenia) o Phantom limbs; supernumerary phantom limbs • Brain damage leading to disorders of body representation – suggest predominant involvement of right posterior parietal cortex and ipsilesional subcortical regions, other areas: lateral prefrontal and premotor cortex • Patient 1 – damage due to dorso-medial parietal cortex; 55 year old; male, epilepsy since 14 o Partial sensorimotor seizures affected left hand, controlled under medication until onset of paroxysmal episodes; 9 years, current hospitalization o Increasing pressure in entire left hemi-body  Left half of head, upper part of left trunk, left arm, left leg no longer belonging to him – disconnected from rest of body; divided into two parts o During sensations – localized self as within right side of body  Invaded by a stranger in his left hemi-body o Simple partial seizures occurred on daily basis and lasted ~ 1 min • Patient 2 – damage to right dorso-medial prefrontal cortex; 30 year old; pharmaco- resistant epilepsy; seizures started at age of 11 – intense feelings of altered bodily awareness o Complex partial seizures – altered body awareness, total loss or strongly diminished awareness of bodily signals  Predominately lower trunk and legs; lesser degree – upper trunk and neck  Impression that below neck was “numb”, “useless”, inaccessible to conscious awareness while head – light, detached from rest of body o Felt “as an observer of his body and as the one being observed” at the same time o Disconnection from his own thoughts and past; no longer in control of his actions and speech, like being a robot o Ranging from one per day to one per hour; most often occurred during phases of relaxation; duration ~30 sec. o Executive and attentional deficits: high distractability and intrusive thoughts; as well as mild impairments in mental flexibility o Depersonalization – feel detached, alienated from body and/or mental processes, feeling as an outside “observer”, while having no or less control over their actions • Importance of right posterior and medial parietal cortex for illusory own body perceptions Multi­Sensory Integration • Intense pain in limb that doesn’t exist – how to treat it? o Pain killers to hypnotism – nothing worked • The role vision has in understanding sense of physical self o Visual affirmation of limb moving – we don’t think of it – take advantage of it o Understanding body – feel limb move, see it o Corresponds to what he feel and see it; integrating visual representational and limbs moving in his face • Brain sending signals to arm, try to clench it, command sign
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