Historical Notes on Historical Notes on Reorganization of Function and Reorganization of Function and

NeuroplasticityNeuroplasticityHistory has been filledHistory has been filled

with philosophers, men with philosophers, men

and women of medicineand women of medicine

and science that have all and science that have all

been intrigued by the been intrigued by the

workings of the brain…workings of the brain…

BUT has anyone really figuredBUT has anyone really figured

it out?.....it out?.....

SPONTANEOUS RECOVERYSPONTANEOUS RECOVERY IN EARLY HISTORY DISEASE IN EARLY HISTORY DISEASE

WAS THOUGHT TO BE A WAS THOUGHT TO BE A RESULT OF NATURAL OR RESULT OF NATURAL OR SUPERNATURAL FORCESSUPERNATURAL FORCES

AS TIME WENT ON THE BELIEF AS TIME WENT ON THE BELIEF THAT IT WAS THE FORCES OF THAT IT WAS THE FORCES OF NATURE ALONE THAT WERE NATURE ALONE THAT WERE RESONSIBLE FOR RESONSIBLE FOR SPONTANEOUS RECOVERY SPONTANEOUS RECOVERY

““NATURE ITSELF FINDS A WAY, NATURE ITSELF FINDS A WAY, THOUGH UNTAUGHT AND THOUGH UNTAUGHT AND UNINSTRUCTED - IT DOES UNINSTRUCTED - IT DOES WHATS PROPER”WHATS PROPER”

~EPIDEMICS VI,5~EPIDEMICS VI,5

NATURE OF DISEASE AND NATURE OF DISEASE AND RECOVERYRECOVERY

DURING THE DURING THE EVOLUTION OF EVOLUTION OF NEUROSCIENCE, THE NEUROSCIENCE, THE IDEA THAT NATURE IDEA THAT NATURE (INTERNAL NATURE OF (INTERNAL NATURE OF THE BODY) BECAME THE BODY) BECAME ACCEPTED AND WAS ACCEPTED AND WAS DISSEMINATED AND DISSEMINATED AND INTERPREDED BY INTERPREDED BY PROMINENT FIGURES IN PROMINENT FIGURES IN MEDICINE DURING THE MEDICINE DURING THE 1919THTH CENTURY CENTURY

P. FLUERNSP. FLUERNS EARLIY IN THE 19EARLIY IN THE 19THTH

CENTURY CENTURY PIERRE PIERRE FLUERENSFLUERENS, A FRENCH , A FRENCH PHYSIOLOGIST, PHYSIOLOGIST, ASSERTED THAT LOBES ASSERTED THAT LOBES ACT AS A WHOLE WITH ACT AS A WHOLE WITH NO SPECIALIZATION OF NO SPECIALIZATION OF FUNCTIONFUNCTION

FLUERENS BELIEFS FLUERENS BELIEFS WERE BASED ON WERE BASED ON ABLATION ABLATION EXPERIMENTS WITH EXPERIMENTS WITH PIGEONSPIGEONS

FLEURENS con’tFLEURENS con’t

LOBES AS A WHOLE:LOBES AS A WHOLE: NO SPECIALIZATIONNO SPECIALIZATION

1)1) When lobes are When lobes are completely removedcompletely removed= = all capabilities lostall capabilities lost

2)2) Partial ablation that Partial ablation that removed nearly all of removed nearly all of the lobethe lobe= = impairment, impairment, but not entire loss of but not entire loss of capabilitiescapabilities

1)1) Small removals in any Small removals in any of the lobesof the lobes= = complete return of complete return of capabilitiescapabilities

SIZE DOES MATTER!SIZE DOES MATTER!((GET YOUR MIND OUT OF THE GUTTER )GET YOUR MIND OUT OF THE GUTTER )

FLEURENS SUPPORTED THE IDEA OF FLEURENS SUPPORTED THE IDEA OF REDUNDANCY AS A FACTOR AFTER REDUNDANCY AS A FACTOR AFTER PARTIAL ABLATIONSPARTIAL ABLATIONS

FLEURENS ALSO BELIEVED THAT THE FLEURENS ALSO BELIEVED THAT THE SIZE OF THE LESION DICTATES THE SIZE OF THE LESION DICTATES THE AMOUNT OF FUNCTIONAL AMOUNT OF FUNCTIONAL RESTORATIONRESTORATION

LOCALIZED OR LOCALIZED OR ANTILOCALIZED?ANTILOCALIZED?

OPPOSED TO OPPOSED TO FLEURENS WAS FLEURENS WAS JOSEPH GALLJOSEPH GALL

GALL BELIVED THAT GALL BELIVED THAT THE BRAIN ACTUALLY THE BRAIN ACTUALLY HAD 27 ABILITIES AND HAD 27 ABILITIES AND PERSONALITES THAT PERSONALITES THAT COULD BE MAPPED COULD BE MAPPED ONTO SPECIFIC AREAS ONTO SPECIFIC AREAS ON THE CEREBRAL ON THE CEREBRAL CORTEXCORTEX

BROCA AND FRITCH/HIZIGBROCA AND FRITCH/HIZIG BROCA’SBROCA’S LOCALIZED LOCALIZED

SPEECH IN THE LEFT SPEECH IN THE LEFT HEMISPHERE IN THE HEMISPHERE IN THE 1980’S1980’S

FRITCH AND HITZIG’SFRITCH AND HITZIG’S DEMONSTRATED THE DEMONSTRATED THE EXCITABILITY OF THE EXCITABILITY OF THE MOTOR CORTEX IN MOTOR CORTEX IN THE 1870’STHE 1870’S

*THIS LAID TO REST THE *THIS LAID TO REST THE

BATTLE IN FAVOR OF BATTLE IN FAVOR OF LOCALIZATION*LOCALIZATION*

CEREBRAL CONNECTIONSCEREBRAL CONNECTIONS THESE DISCOVERIES ALL LEAD TO SIGNIFICANT THESE DISCOVERIES ALL LEAD TO SIGNIFICANT

ADVANCES IN THE DEVELOPMENT OF THE NEURO ADVANCES IN THE DEVELOPMENT OF THE NEURO CONCENTRATIONS AND PATHWAYS IN THE CONCENTRATIONS AND PATHWAYS IN THE HUMAN CEREBRAL CORTEXHUMAN CEREBRAL CORTEX

THESE DEVELOMENTS WERE GENERALY FOCUSED THESE DEVELOMENTS WERE GENERALY FOCUSED ON THE SUBSTRATES OF PERCEPTION, ON THE SUBSTRATES OF PERCEPTION, MOVEMENT,SENSATION, AND SPEECHMOVEMENT,SENSATION, AND SPEECH

FURTHER ADVANCES FACILITATED FURTHER ADVANCES FACILITATED UNDERSTANDING OF THE CONCEPT OF STABLE UNDERSTANDING OF THE CONCEPT OF STABLE CONNECTIONS OF AFFERENT AND EFFORENT CONNECTIONS OF AFFERENT AND EFFORENT PROCESESPROCESES

NEURAL NETWORKSNEURAL NETWORKS

ADVANCES ADVANCES ALSO ALSO TOOKPLACE IN TOOKPLACE IN DILINEATING DILINEATING NEURL NEURL NETWORKS IN NETWORKS IN PATIENTS WITH PATIENTS WITH VISUAL VISUAL DEFECTS DEFECTS HEMIPARESIS, HEMIPARESIS, AND BROCA AND BROCA AND WERNICHE AND WERNICHE APHASIA WHICH APHASIA WHICH CORRESPONDS CORRESPONDS TO DEFINED TO DEFINED COTICAL AREAS COTICAL AREAS OR PROXIMAL OR PROXIMAL CONNECTIONSCONNECTIONS

RECOVERY?RECOVERY?

AS CLINICAL NEUROLOGY AND SURGERY AS CLINICAL NEUROLOGY AND SURGERY GAINED CREDIT AS A TRUE MEDICAL GAINED CREDIT AS A TRUE MEDICAL SPECIALTY, AN AREA OF QUESTION SPECIALTY, AN AREA OF QUESTION AROSE: HOW CAN IT BE EXPLAINED THAT AROSE: HOW CAN IT BE EXPLAINED THAT AFTER A DEFECT OR INJURY THERE CAN BE AFTER A DEFECT OR INJURY THERE CAN BE COMPLETE RECOVERY OF FUNCTION TO COMPLETE RECOVERY OF FUNCTION TO THE PROCESS ATTRIBUTED TO THE THE PROCESS ATTRIBUTED TO THE AFFECTED AREA?AFFECTED AREA?

REORGANIZATIONREORGANIZATION REDUNDANCY COULD REDUNDANCY COULD

NOT ALONE EXPLAIN NOT ALONE EXPLAIN THIS PHENOMENOMTHIS PHENOMENOM

REORGANIZATION REORGANIZATION BECAME THE NEW BECAME THE NEW CONCEPT OF FOCUSCONCEPT OF FOCUS

IT WAS DISCOVERED IT WAS DISCOVERED THAT ONE AREA OF THAT ONE AREA OF THE BRAIN WOULD THE BRAIN WOULD ASSUME ASSUME RESPONSIBILIY FOR RESPONSIBILIY FOR THE DAMAGED AREATHE DAMAGED AREA

THE BRAIN HASTHE BRAIN HAS PLASICITYPLASICITY

WIRED BUT CHANGEABLEWIRED BUT CHANGEABLE

WHILE WE ARE WIRED TO DEVELOP SPEECH IN THE LEFT WHILE WE ARE WIRED TO DEVELOP SPEECH IN THE LEFT HEMESPHERE, WE ARE NOT SOLELY TIED TO THE LEFT HEMESPHERE, WE ARE NOT SOLELY TIED TO THE LEFT SIDE OF THE BRAINSIDE OF THE BRAIN

DISEASE OR INJURY TO THIS PORTION OF THE BRAIN DISEASE OR INJURY TO THIS PORTION OF THE BRAIN DESIGNATED FOR SPEECH DOES NOT MEAN ASSURED DESIGNATED FOR SPEECH DOES NOT MEAN ASSURED APHASIA.APHASIA.

REORGANIZATIONREORGANIZATION ACCORDING TO COTARD, OUR BRAINS ARE ABLE TO ACCORDING TO COTARD, OUR BRAINS ARE ABLE TO

REORGANIZE WHEN MET WITH DAMAGE OR REORGANIZE WHEN MET WITH DAMAGE OR UNDERDEVELOPMENTUNDERDEVELOPMENT

-NEURO CONNECTINS ARE ABLE TO CHANGE!-NEURO CONNECTINS ARE ABLE TO CHANGE! -THESE CONNECTIONS HAVE PLASTICITY-THESE CONNECTIONS HAVE PLASTICITY

COTARDCOTARD ALSO ASSERTED THAT YOUNGER MINDS ARE ALSO ASSERTED THAT YOUNGER MINDS ARE BETTER AT REORGANIZING TO COMENSATE FOR “BAD BETTER AT REORGANIZING TO COMENSATE FOR “BAD WIRING”WIRING”

SOLTMANSOLTMAN, A FEW YEARS LATER, SUPPORTRD WITH THIS , A FEW YEARS LATER, SUPPORTRD WITH THIS IDEA THROUGH TESTS RAN IN PUPPIES WITH HEMISPHERIC IDEA THROUGH TESTS RAN IN PUPPIES WITH HEMISPHERIC ABLATIONSABLATIONS..

-HE FOUND THAT ABLATIONS AT THIS STAGE OF MATURATION,-HE FOUND THAT ABLATIONS AT THIS STAGE OF MATURATION, LESIONS MADE RESULTED IN NO DETECTABLE DIFFERENCES IN LESIONS MADE RESULTED IN NO DETECTABLE DIFFERENCES IN BEHAVIOR OR THE ANIMALBEHAVIOR OR THE ANIMAL

THEREFORE, THE DEVELOPMENTAL TIMING OF THEREFORE, THE DEVELOPMENTAL TIMING OF LESION IMPACT THE EXTENT OF LOSS OR LESION IMPACT THE EXTENT OF LOSS OR RENTENSION OF FUNCTIONRENTENSION OF FUNCTION

JACKSONJACKSON

IN THE 1870’S, IN THE 1870’S, HUGHLING JACKSONHUGHLING JACKSON FOCUSED ON FOCUSED ON THE RATE OF THE DEVELOPMENT OF A LESIONTHE RATE OF THE DEVELOPMENT OF A LESION

*RAPIDLY DEVELOPING LESIONS (STROKE): INCREASED *RAPIDLY DEVELOPING LESIONS (STROKE): INCREASED SYMPTOMOLOGYSYMPTOMOLOGY

*SLOWER DEVELOPING LESIONS (TUMORS): LESS *SLOWER DEVELOPING LESIONS (TUMORS): LESS SYMPTOMOLOGYSYMPTOMOLOGY

*MOMENTUM ALSO AFFECTED RECOVERY TIME AS WELL*MOMENTUM ALSO AFFECTED RECOVERY TIME AS WELL

DIASCHESISDIASCHESIS

VAN MANAKOV EXPANDED ON JACKSON’S VAN MANAKOV EXPANDED ON JACKSON’S “MOMENTUM” CONCEPT BY STATING THAT “MOMENTUM” CONCEPT BY STATING THAT THE EFFECT OF TRUAMA AND RESULTING THE EFFECT OF TRUAMA AND RESULTING DISRUPTIVNESS OF THE MAIN LESION DISRUPTIVNESS OF THE MAIN LESION ALSO DISRUPTS THE SUROUNDING AREA ALSO DISRUPTS THE SUROUNDING AREA OF THE LESION THAT ARE ASSOCIATED OF THE LESION THAT ARE ASSOCIATED STRUCTURALLY AND FUNCTIONALLY TO STRUCTURALLY AND FUNCTIONALLY TO THE DAMAGED AREATHE DAMAGED AREA

VAN MANAKOV CALLED THIS VAN MANAKOV CALLED THIS DIASCHESISDIASCHESIS

HIERARCHY OF PLASTICITYHIERARCHY OF PLASTICITY JACKSON’S SUPPORT OF NEURAL PLASTICITY LEAD JACKSON’S SUPPORT OF NEURAL PLASTICITY LEAD

HIM TO DEVELOP A HIERARCHY OF THE CONCEPT HIM TO DEVELOP A HIERARCHY OF THE CONCEPT OF THE NERVOUS SYSTEMOF THE NERVOUS SYSTEM

AFFERENT AND EFFERIENT FUNCTIONS ARE AFFERENT AND EFFERIENT FUNCTIONS ARE REPRESENTED IN THE BRAIN ON DIFFERENT REPRESENTED IN THE BRAIN ON DIFFERENT LEVELSLEVELS

*LESIONS AT HIGHER LEVELS: *LESIONS AT HIGHER LEVELS: PRODUCE LITTLE OR NO IMPAIRMENTPRODUCE LITTLE OR NO IMPAIRMENT *SAME LESION AT A DEEPER LEVEL: *SAME LESION AT A DEEPER LEVEL: PRODUCES DIFCIENCIESPRODUCES DIFCIENCIES

BEHAVIOR CAPACITY OF A BRAIN LESIONED BEHAVIOR CAPACITY OF A BRAIN LESIONED PATIENT WERE MORE AN EXPRESSION OF PATIENT WERE MORE AN EXPRESSION OF PROPERTIES OF PROPERTIES OF

THE REMAINING NONLESIONED AREATHE REMAINING NONLESIONED AREA

SUMMARY OF EARLY SUMMARY OF EARLY STUDIESSTUDIES

ALL OTHER EARLY STUDIES ALL OTHER EARLY STUDIES REITERATED THE FINDINGS OF REITERATED THE FINDINGS OF STOLTMANN AND JACKSONSTOLTMANN AND JACKSON

1 THE BRAIN HAS THE ABILITY TO REORGANIZE 1 THE BRAIN HAS THE ABILITY TO REORGANIZE TO COMPENSATE FOR DEFICIENCIES IN TO COMPENSATE FOR DEFICIENCIES IN DAMAGED AREASDAMAGED AREAS

2 BECAUSE OF PLASTICITY, LOSS OF COMPLETE 2 BECAUSE OF PLASTICITY, LOSS OF COMPLETE FUNCTION DUE TO LESIONS IS LESSENED AND FUNCTION DUE TO LESIONS IS LESSENED AND IN MANY CASES DEFICIENCIES WERE NOT EVEN IN MANY CASES DEFICIENCIES WERE NOT EVEN DETECTEDDETECTED

3 THE SIZE OF THE LESION MATTERS IN TERMS 3 THE SIZE OF THE LESION MATTERS IN TERMS OF FUNCTIONALITY AND RECOVERYOF FUNCTIONALITY AND RECOVERY

LASHEY (1929)LASHEY (1929) RATS PERFORMING RATS PERFORMING

MEMORY AND RETENTION MEMORY AND RETENTION TASKS IN A MAZE WERE TASKS IN A MAZE WERE FOUND TO REQUIRE ALL FOUND TO REQUIRE ALL AREAS OF THE CEREBRAL AREAS OF THE CEREBRAL CORTEX- CORTEX- THE AMOUNT OF THE AMOUNT OF IMPAIRMENT IN THESE TASKS IMPAIRMENT IN THESE TASKS WAS DIRECTLY WAS DIRECTLY PROPORTIONAL TO THE PROPORTIONAL TO THE AMOUNT OF TISSUE LOSTAMOUNT OF TISSUE LOST

VISUAL CORTEX STUDIES VISUAL CORTEX STUDIES FOUND FOUND THAT COMPLETE THAT COMPLETE REMOVAL OF ASSOCIATED REMOVAL OF ASSOCIATED CORTICAL TISSUES RESULTED CORTICAL TISSUES RESULTED IN LOSS OF ALL PATTERN IN LOSS OF ALL PATTERN DISCRIMINATIONDISCRIMINATION

A REMOVAL THAT A REMOVAL THAT LEFT A LEFT A SMALL AMOUNT OF TISSUE SMALL AMOUNT OF TISSUE REMAINING WAS ENOUGH TO REMAINING WAS ENOUGH TO RETAIN SOME CAPACITYRETAIN SOME CAPACITY

CHAPMAN AND WOLFF CHAPMAN AND WOLFF (1959)(1959)

INTERESTED IN TESTING LASHLY’S IDEA INTERESTED IN TESTING LASHLY’S IDEA THAT THERE WERE REGIONAL THAT THERE WERE REGIONAL DIFFERENCES IN HUMANS RATHER THAN DIFFERENCES IN HUMANS RATHER THAN JUST ANIMALSJUST ANIMALS

1.1. THEY USED PATIENTS THAT HAS LESIONS THEY USED PATIENTS THAT HAS LESIONS EXCIZED SURGICALLYEXCIZED SURGICALLY

2.2. NEUROSUGEONS ESTIMATED THE AMOUNT OF NEUROSUGEONS ESTIMATED THE AMOUNT OF TISSUE LOSTTISSUE LOST

3.3. A BATTERY OF TESTS WERE GIVEN TO TEST A BATTERY OF TESTS WERE GIVEN TO TEST COGNITIVE FUNCTIONCOGNITIVE FUNCTION

4.4. IT WAS FOUND THAT THE ONLY THING TO IT WAS FOUND THAT THE ONLY THING TO AFFECT THE DEGREE OF IMPAIRMENT WES THE AFFECT THE DEGREE OF IMPAIRMENT WES THE SIZE OF THE LESIONSIZE OF THE LESION

0GDEN AND FRANZ (1917)0GDEN AND FRANZ (1917) FOCUSED ON STUDIES ON FOCUSED ON STUDIES ON

COMPLETE RECOVERY OF COMPLETE RECOVERY OF PARALYSIS AFTER PARALYSIS AFTER LESIONS TO THE LESIONS TO THE CORTICAL MOTER REGION CORTICAL MOTER REGION IN MONKEYSIN MONKEYS

• RECOVERY: FORCED TO USE RECOVERY: FORCED TO USE THE HEMIPLEGIC ARMTHE HEMIPLEGIC ARM

• NO RECOVERY: NOT FORCED NO RECOVERY: NOT FORCED TO USE HEMIPLEGIC ARMTO USE HEMIPLEGIC ARM

• THIS SUPPORTED THE THIS SUPPORTED THE IDEA THAT DUE TO IDEA THAT DUE TO PLATICITY OF THE BRAIN, PLATICITY OF THE BRAIN, ADJACENT AREA WERE ADJACENT AREA WERE ABLE TO BE “TAUGHT” ABLE TO BE “TAUGHT” TO ASSUME TO ASSUME RESPONSIBILITIES FOR RESPONSIBILITIES FOR THE DAMAGED CORTEXTHE DAMAGED CORTEX

PLASTICITYPLASTICITY

THE EARLY CONCEPT OF THE EARLY CONCEPT OF “PLASTICITY” WAS CONTINOUSLY “PLASTICITY” WAS CONTINOUSLY TESTED AND REFINED BY TESTED AND REFINED BY NEUROSCIENTIST INTO THE 20NEUROSCIENTIST INTO THE 20THTH CENTURYCENTURY

AN AREA OF PARTICULR INTEREST AN AREA OF PARTICULR INTEREST WAS THE PLASTICITY OF CHILDREN WAS THE PLASTICITY OF CHILDREN COMPARED TO ADULTSCOMPARED TO ADULTS

PLASTICITYPLASTICITY SOME OF THE PROMINENT RESEARCHERS OF THE SOME OF THE PROMINENT RESEARCHERS OF THE

EARLY 20EARLY 20THTH CENTURY WERE: CENTURY WERE:

*HINSHELWOOD(1904)/THOMAS(1905): *HINSHELWOOD(1904)/THOMAS(1905): FOCUS: THEACHING DYSLEXIC CHILDREN TO WRITE FOCUS: THEACHING DYSLEXIC CHILDREN TO WRITE WITH LEFT HAND TO STREGTHEN RIGHT ANGULAR WITH LEFT HAND TO STREGTHEN RIGHT ANGULAR GYRUS TO ASSUME THE FUNCTION OF READINGGYRUS TO ASSUME THE FUNCTION OF READING

*HILLER (1954)*HILLER (1954)FOCUS: 14 Y/O PATIENT WITH LEFT FOCUS: 14 Y/O PATIENT WITH LEFT HEMISPHERECTOMY FOR TUMOR REMOVAL POST-HEMISPHERECTOMY FOR TUMOR REMOVAL POST-SURGICALLY WAS APHASIC-COMPARED TO OLDER SURGICALLY WAS APHASIC-COMPARED TO OLDER PATIENTS WHO UNDERWENT THE SAME PATIENTS WHO UNDERWENT THE SAME PROCEEDURE-HILLER’S PATIENT SHOWED PROCEEDURE-HILLER’S PATIENT SHOWED CONSIDERABLE RECOVERY IN UNDERSTANDING AND CONSIDERABLE RECOVERY IN UNDERSTANDING AND EXPRESSION OF SPEECHEXPRESSION OF SPEECH

FOERSTER and GOLDSTEINFOERSTER and GOLDSTEIN

FOERSTER:FOERSTER: FOCUSED ON THE CHANGES IN THE NERVOUS SYSTEM FOCUSED ON THE CHANGES IN THE NERVOUS SYSTEM

THAT OCCUR AFTER INJURYTHAT OCCUR AFTER INJURY CONCEPT OF REGENERATION AND REORGANIZATION AS CONCEPT OF REGENERATION AND REORGANIZATION AS

THE FEATURES OF RECOVERYTHE FEATURES OF RECOVERY AS A NEUROSURGEON, MAIN EMPHASIS WAS ON ANALYSIS AS A NEUROSURGEON, MAIN EMPHASIS WAS ON ANALYSIS

OF REORGANIZATION AS AN ASPECT OF SURGICAL OF REORGANIZATION AS AN ASPECT OF SURGICAL INTERVENTIONINTERVENTION

GOLDSTEIN:GOLDSTEIN: NOT CONCERNED WITH ANATOMOPHYSIOLOGIC ASPECTSNOT CONCERNED WITH ANATOMOPHYSIOLOGIC ASPECTS MORE FOCUSED ON THE DRIVE AND WILL OF THE PATIENT MORE FOCUSED ON THE DRIVE AND WILL OF THE PATIENT

TO REACH OPTIMAL ADAPTATIONTO REACH OPTIMAL ADAPTATION INSTEAD OF PLACING EMPHASIS ON DEFECT, PATIENTS INSTEAD OF PLACING EMPHASIS ON DEFECT, PATIENTS

WITH BRAIN INJERIES NEED TO “REORGANIZE” AND IN WITH BRAIN INJERIES NEED TO “REORGANIZE” AND IN EFFECT, FOCUS ON ADAPTABILITY RATHER THAN EFFECT, FOCUS ON ADAPTABILITY RATHER THAN ELIMINATING SYMPTOMSELIMINATING SYMPTOMS

DEVELOPMENT OF FUNCTIONAL DEVELOPMENT OF FUNCTIONAL IMAGING PROCEDURESIMAGING PROCEDURES

1.) 1.) MRIMRI (MAGNETIC RESONANCE IMAGING) (MAGNETIC RESONANCE IMAGING) : : non-evasive technique that records the responses to non-evasive technique that records the responses to

radio waves, or other forms of energy, of different radio waves, or other forms of energy, of different types of molecules in a magnetic field.types of molecules in a magnetic field.

*Different tissues of the body emit different amounts *Different tissues of the body emit different amounts of energy in response to pulses.of energy in response to pulses.

2.) 2.) PET SCANPET SCAN (POSITRON EMISSION (POSITRON EMISSION TOMOGRAPHY)TOMOGRAPHY) : :

non-evasive technique that monitors regional non-evasive technique that monitors regional cerebral blood flow in the brain by recording the cerebral blood flow in the brain by recording the emission, or radiation, of emission, or radiation, of gamma raysgamma rays; produces a ; produces a color-coded record of brain activity.color-coded record of brain activity.

**Gamma rays:Gamma rays: emitted and radiate in opposite emitted and radiate in opposite directions and can be recorded by a ring of detectors directions and can be recorded by a ring of detectors around the person’s head.around the person’s head.

DEVELOPMENT OF FUNCTIONAL DEVELOPMENT OF FUNCTIONAL IMAGING PROCEDURESIMAGING PROCEDURES

3.) 3.) SPECT SCAN SPECT SCAN (SINGLE PHOTON EMISSION (SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY):COMPUTED TOMOGRAPHY):

brain imaging system similar to a PET scan, but does brain imaging system similar to a PET scan, but does not produce as clearly defined images as the PET scan.not produce as clearly defined images as the PET scan.

4.) 4.) CT SCANCT SCAN (COMPUTED/COMPUTERIZED (COMPUTED/COMPUTERIZED TOMOGRAPHY SCAN):TOMOGRAPHY SCAN):

non-evasive system used for brain imaging or non-evasive system used for brain imaging or visualizing other organs of the body; computer builds a visualizing other organs of the body; computer builds a 3-D picture from a series of cross-sectional X-rays taken 3-D picture from a series of cross-sectional X-rays taken over evenly spaced time intervals over time. *(A.k.a. over evenly spaced time intervals over time. *(A.k.a. CAT scanCAT scan, or , or computed axial tomography scancomputed axial tomography scan)*)*

[By 1995, PET scans were being used to study patients [By 1995, PET scans were being used to study patients

with stroke in either the left or right hemispheres of thewith stroke in either the left or right hemispheres of the brain to assess possible damage]brain to assess possible damage]

Kertesz (1993)Kertesz (1993)

QUESTIONED HOW THE RIGHT QUESTIONED HOW THE RIGHT HEMISPHERE STRUCTURES RECOVERED HEMISPHERE STRUCTURES RECOVERED AFTER BRAIN INJURY OR STROKEAFTER BRAIN INJURY OR STROKE

THE IDEA THAT THE CAPACITY OF THE THE IDEA THAT THE CAPACITY OF THE RIGHT HEMISPHERE WAS RESPONSIBLE RIGHT HEMISPHERE WAS RESPONSIBLE FOR CERTAIN FUNCTIONS SINCE AS FAR FOR CERTAIN FUNCTIONS SINCE AS FAR BACK AS NIELSEN (1946)BACK AS NIELSEN (1946)

Hubel & Wiesel (1970)Hubel & Wiesel (1970) DECADES AFTER WWII, THE FIELD OF NEURAL DECADES AFTER WWII, THE FIELD OF NEURAL

PLASTICITY DEVELOPED FROM THE EXPERIMENTS PLASTICITY DEVELOPED FROM THE EXPERIMENTS OF HUBEL & WIESEL OF HUBEL & WIESEL

FOCUS WAS SPECIFICALLY ON THE IDEA OF THE FOCUS WAS SPECIFICALLY ON THE IDEA OF THE CRITICAL PERIODCRITICAL PERIOD, WHICH IS THE DETERMINED , WHICH IS THE DETERMINED STATE OF DEVELOPMENT AT WHICH A PERSON STATE OF DEVELOPMENT AT WHICH A PERSON OR ANIMAL IS OPTIMALLY READY TO ACQUIRE OR ANIMAL IS OPTIMALLY READY TO ACQUIRE SOME PATTERN OF BEHAVIOR (I.E. SIGHT BEGINS SOME PATTERN OF BEHAVIOR (I.E. SIGHT BEGINS ONCE THE EYES ARE FIRST OPEN AND EXPOSED ONCE THE EYES ARE FIRST OPEN AND EXPOSED TO STIMULI, SUCH AS LIGHT).TO STIMULI, SUCH AS LIGHT).

SUGGESTED THE NEURAL AND SENSORY SUGGESTED THE NEURAL AND SENSORY SYSTEMS WERE HIGHLY PLASTIC DURING A BRIEF SYSTEMS WERE HIGHLY PLASTIC DURING A BRIEF POINT IN DEVELOPMENT.POINT IN DEVELOPMENT.

Johnson & Almli (1978)Johnson & Almli (1978) DISCUSSED METHODS OF RECOVERY:DISCUSSED METHODS OF RECOVERY: SUBSTITUTIONSUBSTITUTION- IMPLYING SURPLUS OR - IMPLYING SURPLUS OR

MULTIPLE REPRESENTATION IN THE CNS, WHICH MULTIPLE REPRESENTATION IN THE CNS, WHICH WORKS AS A SECONDARY NEURAL SYSTEM TO WORKS AS A SECONDARY NEURAL SYSTEM TO TAKE OVER THE FUNCTION OF A PRIMARY ONE.TAKE OVER THE FUNCTION OF A PRIMARY ONE.

VICARIATION/EQUIPOTENTIALITYVICARIATION/EQUIPOTENTIALITY- NON-- NON-SPECIFIED BRAIN AREAS THAT ASSUME THE SPECIFIED BRAIN AREAS THAT ASSUME THE FUNCTIONS OF THE DAMAGED ONE.FUNCTIONS OF THE DAMAGED ONE.

REGENERATIONREGENERATION--NEW GROWTH AFTER NEW GROWTH AFTER NEURON DAMAGE.NEURON DAMAGE.

COLLATERAL SPROUTINGCOLLATERAL SPROUTING-- NEW GROWTH NEW GROWTH IN AREAS ADJACENT TO DAMAGED TISSUE.IN AREAS ADJACENT TO DAMAGED TISSUE.

DENERVATION SENSITIVITYDENERVATION SENSITIVITY-- INCREASED INCREASED SENSITIVITY TO TRANSMITTER SUBSTANCES BY SENSITIVITY TO TRANSMITTER SUBSTANCES BY NEURONS THAT HAVE LOST DUE TO NEURONS THAT HAVE LOST DUE TO INNERVATION DUE TO BRAIN DAMAGE INNERVATION DUE TO BRAIN DAMAGE

OTHER DEVELOPMENTSOTHER DEVELOPMENTS Early 1980s, evidence of plasticity in adults Early 1980s, evidence of plasticity in adults

begins to emerge, along with the begins to emerge, along with the development of sensory and motor maps.development of sensory and motor maps.

Huttenlocher Huttenlocher (1990) studied the cerebral (1990) studied the cerebral cortex and developmental changes in cortex and developmental changes in relation to early learning in childhood.relation to early learning in childhood.

Pascual-LeonePascual-Leone (1993) researched the (1993) researched the increased cortical responses of the index increased cortical responses of the index finger in reading Braille.finger in reading Braille.

INTERMODAL PLASTICITYINTERMODAL PLASTICITY In the late 1960s, In the late 1960s, Paul Bach-y-RitaPaul Bach-y-Rita developed developed

tactile vision substitution systemtactile vision substitution system (TVSS) to (TVSS) to investigate intermodal plasticity among people investigate intermodal plasticity among people who were blind. who were blind.

The TVSS allowed the blind eye to receive “visual” The TVSS allowed the blind eye to receive “visual” information by mechanical vibrations or electric information by mechanical vibrations or electric pulses. pulses.

The TVSS was never a fully accepted, but effected The TVSS was never a fully accepted, but effected the concept of intermodal plasticity.the concept of intermodal plasticity.

Studies using intermodal plasticity in humans that Studies using intermodal plasticity in humans that were blind showed activated brain activity in brain were blind showed activated brain activity in brain regions normally associated with vision during regions normally associated with vision during other forms of stimulation (i.e. auditory).other forms of stimulation (i.e. auditory).

Sensory MappingSensory Mapping

Sensory MappingSensory Mapping may explain why may explain why people with an amputated limb way people with an amputated limb way still feel or perceive sensations and still feel or perceive sensations and inputs although there is no longer a inputs although there is no longer a limb present to receive stimulation, limb present to receive stimulation, known as the “phantom limb,” or why known as the “phantom limb,” or why blind people can learn to read Braille blind people can learn to read Braille or seem to have heightened hearing. or seem to have heightened hearing.

SUMMARYSUMMARY The study of neural plasticity and recovery of The study of neural plasticity and recovery of

function after surgery has continued for more function after surgery has continued for more than a century, but has really exploded in the than a century, but has really exploded in the last 10 years.last 10 years.

Addresses theoretical and empirical issues Addresses theoretical and empirical issues related to neural plasticity.related to neural plasticity.

Findings in neural plasticity have lead to major Findings in neural plasticity have lead to major influences on the development of rehabilitation influences on the development of rehabilitation programs.programs.

SUMMARYSUMMARY *Dramatics advance in *Dramatics advance in

technical tools that have technical tools that have enhanced the field: MRI, PET, enhanced the field: MRI, PET, SPECT, and CT scans, which SPECT, and CT scans, which have in turn helped to have in turn helped to advance other neurological advance other neurological discoveries.discoveries.

*The goal is to develop *The goal is to develop answers and effective answers and effective treatments for people who treatments for people who suffer from cognitive and/or suffer from cognitive and/or behavioral problems due to behavioral problems due to some neurological disease or some neurological disease or dysfunction dysfunction