Biological Psychology – Mod. 3 & 4 The Split-Brain Phenomenon Left-handedness Synaptic Plasticity Biomedical Therapies General Psychology 1 February 15,

Biological Psychology – Mod. 3 & 4Biological Psychology – Mod. 3 & 4

The Split-Brain PhenomenonThe Split-Brain PhenomenonLeft-handednessLeft-handedness

Synaptic PlasticitySynaptic PlasticityBiomedical TherapiesBiomedical Therapies

General Psychology 1General Psychology 1

February 15, 2005February 15, 2005Class #7Class #7

The Split-Brain The Split-Brain PhenomenonPhenomenon

Corpus CallosumCorpus Callosum Large band of neural fibers that connects the two Large band of neural fibers that connects the two

brain hemispheresbrain hemispheres The two sides of our brains serve different The two sides of our brains serve different

functions (lateralized or specialization of tasks): functions (lateralized or specialization of tasks): Left hemisphere: Language, math, logicLeft hemisphere: Language, math, logic Right hemisphere: spatial abilities, face recognition, Right hemisphere: spatial abilities, face recognition,

visual imagery, musical and artistic abilities, emotional visual imagery, musical and artistic abilities, emotional tasks.tasks.

This is the case for almost all righthanders This is the case for almost all righthanders (about 95%) and about half of lefthanders (about 95%) and about half of lefthanders

Important aspects of this Important aspects of this divided brain phenomenondivided brain phenomenon

Information from left half of field of vision is Information from left half of field of vision is received only by your right hemisphere, and received only by your right hemisphere, and information from the right half of your field of information from the right half of your field of vision is received only by your left vision is received only by your left hemispherehemisphere

Don’t get confused here as Don’t get confused here as eacheach eye receives eye receives sensorysensory information from both right and left information from both right and left visual fields. But this information is only visual fields. But this information is only transmitted from a particular visual field to a transmitted from a particular visual field to a particular brain hemisphereparticular brain hemisphere


The left hemisphere receives information The left hemisphere receives information from and controls movements of the right from and controls movements of the right side of the body, whereas the right side of the body, whereas the right hemisphere receives input from and controls hemisphere receives input from and controls movements of the left side of the bodymovements of the left side of the body

Tests show that almost all right-handers Tests show that almost all right-handers (over 95%) process speech in the left (over 95%) process speech in the left hemispherehemisphere


Left-handers are more diverse:Left-handers are more diverse: 60% process speech in the left 60% process speech in the left

hemispherehemisphere 5% process speech in the right 5% process speech in the right

hemispherehemisphere 35% use both hemispheres about 35% use both hemispheres about

equally equally (half of the time)(half of the time)

Split-Brain ExperimentsSplit-Brain Experiments

Vogel and Bogen (1961)Vogel and Bogen (1961) Sperry and GazzanigaSperry and Gazzaniga

Conducted many experiments from Conducted many experiments from 1960’s through the 1980’s1960’s through the 1980’s


FIELD OF VISION

LEFT RIGHT

HEMISPHERE

LEFTRIGHT

When the patient is asked “What do you see?”They answer…


FIELD OF VISION

LEFT RIGHT

HEMISPHERE

LEFTRIGHT

When the patient is asked “What do you see?”They answer…

The Split-Brain The Split-Brain PhenomenonPhenomenonFIELD OF VISIONLEF

T

RIGHT

HEMISPHERELEFT RIGHT

The same patient who has just said they could not see the picture is now asked to take their left hand and touch the ‘happy face” picture… What happens now???

The Split-Brain The Split-Brain PhenomenonPhenomenonFIELD OF VISIONLEF

T

RIGHT

HEMISPHERELEFT

RIGHT

Now, with the object in the patient’s hand, he/she is asked “what is in your hand”…what is their answer this time???

Severed Corpus Collusom: Severed Corpus Collusom: VideoVideo

11stst scene: scene: “ “Joe” is flashed words in his right field of vision Joe” is flashed words in his right field of vision

(“storm” and “piano”) and has no trouble (“storm” and “piano”) and has no trouble saying themsaying them

He is then flashed the word “phone” in the left He is then flashed the word “phone” in the left field of vision…and he can’t say itfield of vision…and he can’t say it

““didn’t see that”didn’t see that” But when asked to draw a picture of what he But when asked to draw a picture of what he

saw with his left hand…he draws a telephone saw with his left hand…he draws a telephone but since its still in his left field of vision he still but since its still in his left field of vision he still can’t verbalize what he just drew can’t verbalize what he just drew

Severed Corpus Callosum: Severed Corpus Callosum: VideoVideo

But then when asked to draw it with But then when asked to draw it with his left hand but in his right field of his left hand but in his right field of vision…he is able to say what he vision…he is able to say what he drew (“oh, phone”)drew (“oh, phone”) Very interesting…Very interesting…


22ndnd scene: scene: Joe is flashed words simultaneously in Joe is flashed words simultaneously in

both fields of vision – “toad” in left field both fields of vision – “toad” in left field and “stool” in right field…and “stool” in right field…

He can’t say “toad” but can draw it with He can’t say “toad” but can draw it with left handleft hand

He can say ‘stool” and by speaking it, he He can say ‘stool” and by speaking it, he is able to let the right hemisphere in on is able to let the right hemisphere in on the “secret”the “secret”


33rdrd scene: scene: Again, two words simultaneously…”bell” Again, two words simultaneously…”bell”

appears in his left field of vision and appears in his left field of vision and “music” in his right field of vision“music” in his right field of vision

When asked to point with his left hand When asked to point with his left hand to what he saw, Joe points to a picture of to what he saw, Joe points to a picture of a bell but is not really sure why so he a bell but is not really sure why so he makes up a story that seems to be makes up a story that seems to be plausible…he’s basically trying to figure plausible…he’s basically trying to figure out what's going on out what's going on

Severed Corpus Callosum : Severed Corpus Callosum : VideoVideo

Joe’s left hemisphere is trying to Joe’s left hemisphere is trying to interpret what is going on – trying to interpret what is going on – trying to find a cause and effectfind a cause and effect

Left hemisphere is responsible for Left hemisphere is responsible for making sense out of the mysterymaking sense out of the mystery

According to Gazzaniga: “the left According to Gazzaniga: “the left hemisphere is where the action is”…hemisphere is where the action is”…

Severed Corpus Callosum : Severed Corpus Callosum : VideoVideo

Final scene:Final scene: Pictures are shown of faces made out Pictures are shown of faces made out

of fruit, meat, etc.of fruit, meat, etc. Right hemisphere specializes in Right hemisphere specializes in

locating faces and left is better at locating faces and left is better at finding elements involved…finding elements involved…

So what happens?So what happens? Right hemisphere sees it as a face and Right hemisphere sees it as a face and

left hemisphere sees it as a fruitleft hemisphere sees it as a fruit

Still being performed but now very rareStill being performed but now very rare

Cutting apart the two hemispheres of the human Cutting apart the two hemispheres of the human brain is a drastic step, and it is one of the most brain is a drastic step, and it is one of the most controversial operations ever performedcontroversial operations ever performed

Yet it can succeed, when all else fails, in Yet it can succeed, when all else fails, in relieving violent, drug-resistant epileptic relieving violent, drug-resistant epileptic seizuresseizures

This surgery is becoming more and more rare – This surgery is becoming more and more rare – Instead, neurosurgeons are using a variety of Instead, neurosurgeons are using a variety of neuroscience techniques to reduce the amount neuroscience techniques to reduce the amount of tissue removed in brain surgery of tissue removed in brain surgery

Hardly ever performed now because also Hardly ever performed now because also because of new and effective medications that because of new and effective medications that help prevent seizureshelp prevent seizures

Left Handedness: Curse or Left Handedness: Curse or

BlessingBlessing Around Around ten percent of Americans ten percent of Americans

are left-handedare left-handed, and of those, , and of those, there are twice as many lefty males there are twice as many lefty males as femalesas females

A curse???A curse???

Possible disadvantagesPossible disadvantages Medical literature reports that lefties are Medical literature reports that lefties are

more accident prone…Lefties are six more accident prone…Lefties are six times likelier to die in an accident, and times likelier to die in an accident, and four times likelier to die while drivingfour times likelier to die while driving

For example: they are more likely to have For example: they are more likely to have their fingers amputated by power-tools, their fingers amputated by power-tools, suffer more wrist fractures (Corliss, 1984)suffer more wrist fractures (Corliss, 1984)

Lefties are more susceptible to allergies, Lefties are more susceptible to allergies, reading disabilities, and migraine reading disabilities, and migraine headaches (Geschwind and Behan, 1984)headaches (Geschwind and Behan, 1984)

Or a blessing???Or a blessing???

Possible advantagesPossible advantages Lefties are more common among Lefties are more common among

professional baseball and cricket professional baseball and cricket players, architects and artists players, architects and artists

Corpus callosum is about 11% greater in Corpus callosum is about 11% greater in left-handers… left-handers… Leading to greater integration of both brain Leading to greater integration of both brain

hemispheres in processing informationhemispheres in processing information

The Effects of the Brain on The Effects of the Brain on Handedness: Some TheoriesHandedness: Some Theories

Damage to the brain, an insufficient Damage to the brain, an insufficient supply of oxygen to the brain, and a supply of oxygen to the brain, and a difficult birth are thought to cause difficult birth are thought to cause left-handedness…left-handedness… This theory has been accepted by many, This theory has been accepted by many,

as the number of lefties who fall under as the number of lefties who fall under these categories is surprisingly highthese categories is surprisingly high

An unusually high percentage of An unusually high percentage of mentally retarded children are left-mentally retarded children are left-handed handed

The Effects of the Brain on The Effects of the Brain on Handedness: Some TheoriesHandedness: Some Theories

Twins are notorious for having Twins are notorious for having difficult births, and have a high rate difficult births, and have a high rate of left-handedness too...about 20%, of left-handedness too...about 20%, which is twice the normal ratewhich is twice the normal rate

It is also thought that the tendency It is also thought that the tendency to have difficult births is genetic, to have difficult births is genetic, which would back up the statistics for which would back up the statistics for left-handedness to run in the family left-handedness to run in the family

Brain Reorganization: Brain Reorganization: Synaptic PlasticitySynaptic Plasticity

Synaptic PlasticitySynaptic Plasticity Often when one area of the brain is Often when one area of the brain is

damaged, other areas may in time damaged, other areas may in time reorganize and take over its functionreorganize and take over its function

Example: Professor at Iona College – a Example: Professor at Iona College – a stroke victimstroke victim It is not uncommon for stroke patients It is not uncommon for stroke patients

who have lost the ability to speak or who have lost the ability to speak or to move a limb to regain function to move a limb to regain function after several weeks of convalescenceafter several weeks of convalescence

How does the brain How does the brain recover?recover?

Essentially what is occurring is a Essentially what is occurring is a “remodeling” of the cerebral cortex “remodeling” of the cerebral cortex after an injury in which sometimes a after an injury in which sometimes a large part of it simply dieslarge part of it simply dies

Of course, this is the exception and Of course, this is the exception and not the rulenot the rule Not all stroke victims recoverNot all stroke victims recover

Even better chances: Plasticity in Even better chances: Plasticity in childrenchildren

Before the functions of young children’s cortical Before the functions of young children’s cortical regions become fixed, their brains are especially regions become fixed, their brains are especially plastic…if the speech areas of an infant’s left plastic…if the speech areas of an infant’s left hemisphere are damaged, the right hemisphere hemisphere are damaged, the right hemisphere will usually take over with will usually take over with no noticeable no noticeable impairmentimpairment of language… of language… Left hemisphere damage does not permanently Left hemisphere damage does not permanently

disrupt language until age 8disrupt language until age 8 Case study: see hand-outCase study: see hand-out

Illustrates that the brain has extraordinary powers of reorganization, Illustrates that the brain has extraordinary powers of reorganization, especially when damaged before it is fully developedespecially when damaged before it is fully developed

Plasticity vs. split-brainPlasticity vs. split-brain

So, if you have a split-brain operation So, if you have a split-brain operation there is no sharing of informationthere is no sharing of information

Yet, if you remove one side of the Yet, if you remove one side of the brain at an early age you will see brain at an early age you will see synaptic plasticity take place and synaptic plasticity take place and he/she will likely live a normal lifehe/she will likely live a normal life

Biomedical TherapiesBiomedical Therapies

PsychosurgeryPsychosurgery LobotomiesLobotomies

Electroconvulsive Therapy (ECT)Electroconvulsive Therapy (ECT) Drug TherapiesDrug Therapies

PsychosurgeryPsychosurgery

This is one type of treatment used for This is one type of treatment used for some of the most devastating some of the most devastating psychological disorders (like psychological disorders (like schizophrenia) in which surgery is schizophrenia) in which surgery is performed that removes or destroys performed that removes or destroys brain tissue in an effort to change brain tissue in an effort to change behaviorbehavior This is a drastic biomedical interventionThis is a drastic biomedical intervention A last resort operationA last resort operation

LobotomiesLobotomies

Egas Moniz (1935)Egas Moniz (1935) Developed the best known psychosurgical Developed the best known psychosurgical

operation – the operation – the lobotomylobotomy Moniz found that when he surgically cut Moniz found that when he surgically cut

the nerves that connect the frontal lobes the nerves that connect the frontal lobes with the emotion-controlling centers of with the emotion-controlling centers of the inner brain, uncontrollably emotional the inner brain, uncontrollably emotional and violent patients were calmedand violent patients were calmed

His hope was to disconnect emotion from His hope was to disconnect emotion from thoughtthought


During the 1940’s and 1950’s around During the 1940’s and 1950’s around 50,000 or more severely disturbed 50,000 or more severely disturbed individuals were “lobotomized” and individuals were “lobotomized” and Moniz was honored with a Nobel Moniz was honored with a Nobel PrizePrize

Some of his patients are still alive Some of his patients are still alive todaytoday


At first, his procedure was welcomed by the At first, his procedure was welcomed by the medical community…medical community… Immediate relief from emotional anguishImmediate relief from emotional anguish

Unfortunately, the side effects were Unfortunately, the side effects were drastic…drastic… Although, intellect appeared virtually Although, intellect appeared virtually

unaffected – these patients showed unaffected – these patients showed serious changes in their personalityserious changes in their personality

Becoming irresponsible and childishBecoming irresponsible and childish


They lost the ability to carry out plans and They lost the ability to carry out plans and most became unemployedmost became unemployed

The lobotomy had produced a The lobotomy had produced a permanently lethargic and immature permanently lethargic and immature personalitypersonality

So, although the pathological emotional So, although the pathological emotional problems had been eliminated – so too problems had been eliminated – so too had the normal aspects of that person’s had the normal aspects of that person’s personalitypersonality

No longer performed…No longer performed…

Lobotomies are no longer performed Lobotomies are no longer performed for obvious reasons…for obvious reasons…

Electroconvulsive Therapy Electroconvulsive Therapy (ECT)(ECT)

This is the controversial practice of This is the controversial practice of “shock” treatment“shock” treatment

A less-drastic manipulation of the A less-drastic manipulation of the brain than psychosurgerybrain than psychosurgery

First introduced in 1938First introduced in 1938

Early treatments…Early treatments…

A wide-awake person was strapped A wide-awake person was strapped to a table and jolted with about 100 to a table and jolted with about 100 volts of electricity to the brainvolts of electricity to the brain

Produced violent convulsions and Produced violent convulsions and momentary unconsciousnessmomentary unconsciousness

Convulsions sometimes caused injuryConvulsions sometimes caused injury Separated shoulders, etc.Separated shoulders, etc.

Today…Today…

Its done differently as the patient is Its done differently as the patient is given a general anesthetic and given a general anesthetic and muscle relaxantmuscle relaxant See video clipSee video clip

Used primarily to treat severely Used primarily to treat severely depressed individuals, schizophrenics, depressed individuals, schizophrenics, OCD sufferers, etc.OCD sufferers, etc.

Only used after drug treatments have Only used after drug treatments have been unsuccessfulbeen unsuccessful

Drug TherapiesDrug Therapies

By far the most widely used biomedical By far the most widely used biomedical treatment… treatment… They were introduced in 1950’s and have They were introduced in 1950’s and have

greatly reduced the need for hospitalizationgreatly reduced the need for hospitalization Antipsychotic, antianxiety, and Antipsychotic, antianxiety, and

antidepressant drugs have been used antidepressant drugs have been used effectively to help calm individuals, reduce effectively to help calm individuals, reduce emotional stress in people and lift the spirits emotional stress in people and lift the spirits of the clinically depressed of the clinically depressed

Effectiveness???Effectiveness???

Drugs such as antianxiety drugs and Drugs such as antianxiety drugs and antidepresants are not a cure…but antidepresants are not a cure…but they do reduce the symptoms and they do reduce the symptoms and help a person function…help a person function… See video clipSee video clip

Biological Psychology – Mod. 3 & 4 The Split-Brain Phenomenon Left-handedness Synaptic Plasticity Biomedical Therapies General Psychology 1 February 15,

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