Lecture 17 (03/28/2011) (Lateralization in the Brain) PSY 215. Lecture 17 Topic: Lateralization in the Brain Chapter 14.

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1 PSY 215 Lecture 17 (03/28/2011) (Lateralizatin in the Brain) Dr. Achtman PSY 215 Lecture 17 Tpic: Lateralizatin in the Brain Chapter 14.1, pages Crrectins: Nne needed Annuncements: Wednesday will be review fr Exam 3 s please cme with questins t ask. Lecture Ntes: Lateralizatin is the idea that the tw halves f the brain's cerebral crtex -- left and right -- execute different functins. Sme tpics we studied this semester that are lateralized in the brain: (examples included) Smatsensatin (S1) What is felt n the right side will be prcessed in left hemisphere and vice-versa Visin (V1) The right visual field ends up in the left hemisphere f the brain and vice-versa Mvement T initiate a mvement such as writing with yur right hand, the signal begins in the left hemisphere Attentin Hemineglect primarily ccurs with damage t the right parietal crtex and the left side is neglected Language 96% f ppulatin has language in the left hemisphere. Language is dminant in the left side Brain Develpment f bth hemispheres 1. Smatsensry and mtr systems are crssed 2. Sme functins are primarily lcalized in ne hemisphere (i.e. language) Smatsensry and mtr systems in each hemisphere represent the cntra (ppsite) lateral(side) Mtr crtex Areas that have mre crtical real estate have finer mtr cntrl. This is represented by the versized lips, muth, jaw, and hands *(slide shws left M1 which cntrls right side) Smatsensry crtex The amunt f crtex devted t that part f the bdy is related t the fine detail we can sense. This is represented by the versized lips, muth, jaw, and hands. *(slide shws left S1 which cntrls right side) Written by:{sj Sheets}, {ssheets6@naz.edu} Page 1 f 5

Anatmy f the Visual System: Infrmatin frm right visual field ges t bth eyes and ultimately ends up in the left primary visual crtex and vice-versa Sme inf gets acrss and sme stays n same side *image

Inf is prcessed in a very specific part f brain. A neurn in V1 will have a small lcalized receptive field.

2 Anatmy f the Visual System: Infrmatin frm right visual field ges t bth eyes and ultimately ends up in the left primary visual crtex and vice-versa Sme inf gets acrss and sme stays n same side *image frm slide Receptive field: stimulus in specific lcatin will change the activity in that neurn Visual system gets mre cmplex as we mve thrugh the visual prcessing stream. Inf is prcessed in a very specific part f brain. A neurn in V1 will have a small lcalized receptive field. Receptive fields get larger as inf travels t higher areas Example: Receptive Field in right visual field will activate a neurn in left V1 Infrmatin sent t VI then t V2 and s frth Cmmissure: a pathway that carries infrmatin frm ne hemisphere t anther Anterir: cnnects the tw tempral lbes Hippcampal: cnnects the hippcampus n ne side t the ther Crpus callsum: Majr highway (main cnnectin between the tw hemispheres) Hmtpic: cnnectin ging frm ne structure t the same structure in the ther hemisphere (i.e: right S1 t left S1) Hetertpic: cnnectin ging frm ne hemisphere t the ther but a different area (i.e: parietal lbe in ne hemisphere t the frntal lbe in the ther) Ipsilateral: staying within the same hemisphere but ging t different area *image frm slide Written by:{sj Sheets}, {ssheets6@naz.edu} Page 2 f 5

Tls used t investigate lateralizatin: What is split and hw d we knw? Sdium Amytal (Wada test) Inject anesthetic int cartid artery which puts that hemisphere t sleep.

3 Tls used t investigate lateralizatin: What is split and hw d we knw? Sdium Amytal (Wada test) Inject anesthetic int cartid artery which puts that hemisphere t sleep. Brain activity is bserved t measure what the patient is able t d using nly ne half f brain. Risk invlved: can induce strke fmri Brain activity is measured and recrded while subject perfrms a particular task in rder t lcate what part f the brain they are using Frequently used Recrdings Fr epileptic patients: electrdes are implanted in brain t recrd neural activity and determine the rigin r fcal pint f the seizures Surgery Surgen remves part f the brain t Lesin studies Studies f patients with deficits r abnrmalities in the brain, usually damaged by disease r trauma Split brain Term used t describe the result when the crpus callsum, cnnecting the tw hemispheres f the brain is severed t sme degree. The surgical peratin is perfrmed t reduce the frequency and severity f epileptic seizures Nbel prize winner, Dr. Rger W Sperry and Michael Gazzaniga are tw neurscientists wh studied patients wh had surgery t cut the crpus callsum What was learned thrugh Split-Brain experiments? LeftandrighthemispheresreceiveinfrmatinfrmBOTHeyes,butnlytheinfrmatinthat cmesfrmtheppsitevisualfield Eachhemispherehasitswnuniqueabilities(seechartbelw) Leftapparentlyisspecializedfrlanguage rightexcelsnspatialtasks Split brainpatientshavedifficultywithcertaintaskssincethehemispherescanntcmmunicate Individualswithanintactcrpuscallsumdn tshwthesedifficulties ThetwhemispheresfSplit brainpatientsfunctinindependentlyfneanther Theabilitytrecgnizefacesislcatedexclusivelyintherighthemisphere FFA *image frm slide Written by:{sj Sheets}, {ssheets6@naz.edu} Page 3 f 5

4 Nte the specific differences between the tw hemispheres. Specialties Right Hemisphere Cpying f designs, Discriminatin f shapes e.g. picking ut a camuflaged bject, Understanding gemetric prperties, Face recgnitin, Music, humr Glbal hlistic prcessing, Understanding f metaphrs, Expressing emtins, Reading emtins, Recgnize letters, wrds, simple sentences Visu-mtr Left Hemisphere Language cmprehensin (spken, written) and prductin (talking, writing) Analytical, led by lgic Prcess ideas sequentially, step-by-step Visual acuity Lcal prcessing Planning & rganizatin Shared Emtins Negative emtins (fearful murnful feelings), Sensatins n bth side f face, Sund perceived by bth ears, Pain, Hunger, Psitin. Psitive emtins Neurtransmitters Higher levels f nrepinephrine Higher levels f dpamine Grey Matter White Matter rati Mre white-matter (lnger axns) n right mre grey-matter (cell bdies) n the left. Fr mre infrmatin: Simulate a split-brain experiment: interactive activity that gives a clear understanding Awesme vide dcumentary abut patient with severed Crpus callsum: This is the bk cmpanin site: Sme exercises t enhance learning. Select Ch. 14 (frm drp-dwn menu) Select Online Try-it-Yurself (left clumn) Select: Hemisphere Cntrl &discipline_number=24 What des this dancer say abut yu? See if yu are left/right brain dminant Lateral thinking puzzles fr yur amusement and fr yur brains develpment: (9 dts is cl) Written by:{sj Sheets}, {ssheets6@naz.edu} Page 4 f 5

5 Real-life example: Strke victims with right hemisphere brain damage may experience pr depth perceptin, hand-eye crdinatin and shrt term memry. They may als exhibit impulsiveness, pr decisin making and unhealthy habits. Since this part f the brain cntrls judgment, lgic and reasning capabilities, right hemisphere strkes can cause adults t act in a way that thers might find immature, illgical r unusual. A strke n the left side f the brain can lead t a variety f speech and reading disrders, ranging frm slightly slurred speech t ttal illiteracy. Left brain strkes als reflect the inverse f right brain strkes in that they tend t make their victims verly cautius and slw t act. Shrtened attentin spans have als been reprted amng many left brain strke sufferers. Try this: draw a circle with yur right hand and at the same time draw a square with yur left hand. Mst peple cannt d this very well. Hwever, a split-brain patient (as seen n the vide) can d it withut any prblem at all. This is because the tw halves f the brain are perating independent f ne anther. While we have a natural tendency twards ne way f thinking, the tw sides f ur brain wrk tgether in ur everyday lives. Written by:{sj Sheets}, {ssheets6@naz.edu} Page 5 f 5

2. As a caregiver, it s important to build a team/ support network around you (choose one):

2. As a caregiver, it s important to build a team/ support network around you (choose one): Test Questins (Part 1, Chapter 1) 1. Of thse affected by dementia: 50% are nt aware they are changing and 50% are aware they are changing. Of the 50% wh are aware, they will always respnd by becming anxius