the origin and nature of emotions-第15部分

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p　us　to　understand　their　significance　in　health　and　in　disease。



THE　RELATION　BETWEEN　THE　PHYSICAL　STATE　OF　THE　BRAIN…CELLS　AND　BRAIN　FUNCTIONSEXPERIMENTAL　AND　CLINICAL＇*＇

＇*＇　Address　before　The　American　Philosophical　Society；　April　18；　1913。


The　brain　in　all　animals　（including　man）　is　but　the　clearing…house　for　reactions　to　environment；　for　animals　are　essentially　motor　or　neuromotor　mechanisms；　composed　of　many　parts；　it　is　true；　but　integrated　by　the　nervous　system。　　Throughout　the　phylogenetic　history　of　the　race　the　stimuli　of　environment　have　driven　this　mechanism；　whose　seat　of　powerthe　batteryis　the　brain。

Since　all　normal　life　depends　upon　the　response　of　the　brain　to　the　daily　stimuli；　we　should　expect　in　health；　as　well　as　in　disease；　to　find　modifications　of　the　functions　and　the　physical　state　of　the　component　parts　of　this　central　battery　the　brain…cells。　Although　we　must　believe；　then；　that　every　reaction　to　stimuli；　however　slight；　produces　a　corresponding　change　in　the　brain…cells；　yet　there　are　certain　normal；　that　is；　non…diseased；　conditions　which　produce　especially　striking　changes。　The　cell　changes　due　to　the　emotions；　for　example；　are　so　similar；　and　in　extreme　conditions　approach　so　closely　to　the　changes　produced　by　disease；　that　it　is　impossible　to　say　where　the　normal　ceases　and　the　abnormal　begins。

In　view　of　the　similarity　of　brain…cell　changes　it　is　not　strange　that　in　the　clinic　as　well　as　in　daily　life；　we　are　confronted　constantly　by　outward　manifestations　which　are　so　nearly　identical　that　the　true　underlying　cause　of　the　condition　in　any　individual　case　is　too　often　overlooked　or　misunderstood。　In　our　laboratory　experiments　and　in　our　clinical　observations　we　have　found　that　exhaustion　produced　by　intense　emotion；　prolonged　physical　exertion；　insomnia；　intense　fear；　certain　toxemias；　hemorrhage；　and　the　condition　commonly　denominated　surgical　shock；　produce　similar　outward　manifestations　and　identical　brain…cell　changes。

It　is；　therefore；　the　purpose　of　this　paper　to　present　the　definite　results　of　laboratory　researches　which　show　certain　relations　between　alterations　in　brain　functions　and　physical　changes　in　the　brain…cells。

Fear。Our　experiments　have　shown　that　the　brain…cell　changes　due　to　fear　may　be　divided　into　two　stages：　　First；　that　of　hyperchromatism　stimulation；　second；　that　of　hypochromatismexhaustion　（Figs。　5　and　13）。　Hyperchromatism　was　shown　only　in　the　presence　of　the　activating　stimuli　or　within　a　very　short　time　after　they　had　been　received。　This　state　gradually　changed　until　the　period　of　maximum　exhaustion　was　reachedabout　six　hours　later。　　Then　a　process　of　reconstruction　began　and　continued　until　the　normal　state　was　again　reached。

Fatigue。Fatigue　from　overexertion　produced　in　the　brain…cells　like　changes　to　those　produced　by　fear；　these　changes　being　proportional　to　the　amount　of　exertion　（Fig。　4）。　In　the　extreme　stage　of　exhaustion　from　this　cause　we　found　that　the　total　quantity　of　Nissl　substance　was　enormously　reduced。　When　the　exertion　was　too　greatly　prolonged；　it　took　weeks　or　months　for　the　cells　to　be　restored　to　their　normal　condition。　We　have　proved；　therefore；　that　in　exhaustion　resulting　from　emotion　or　from　physical　work　a　certain　number　of　the　brain…cells　are　permanently　lost。　　This　is　the　probable　explanation　of　the　fact　that　an　athlete　or　a　race…horse　trained　to　the　point　of　highest　efficiency　can　reach　his　maximum　record　but　once　in　his　life。　Under　certain　conditions；　however；　it　is　possible　that；　though　some　chromatin　is　forever　lost；　the　remainder　may　be　so　remarkably　developed　that　for　a　time　at　least　it　will　compensate　for　that　which　is　gone。

Hemorrhage。The　loss　of　blood　from　any　cause；　if　sufficient　to　reduce　the　blood…pressure；　will　occasion　a　change　in　the　brain…cells；　provided　that　the　period　of　hypotension　lasts　for　more　than　five　minutes。　This　time　limit　is　a　safeguard　against　permanent　injury　from　the　temporary　hypotension　which　causes　one　to　faint。　If　the　hemorrhage　be　long　continued　and　the　blood…pressure　be　low；　there　will　be　a　permanent　loss　of　some　of　the　brain…cells。　This　explains　why　an　individual　who　has　suffered　from　a　prolonged　hemorrhage　will　never　again　be　restored　to　his　original　powers。

Drugs。According　to　their　effect　upon　the　brain…cells；　drugs　may　be　divided　into　three　classes：　　First；　those　that　stimulate　the　brain…cells　to　increased　activity；　as　strychnin　（Fig。　37）；　second；　those　that　chemically　destroy　the　brain…cells；　as　alcohol　and　iodoform　（Figs。　38　and　39）；　third；　those　that　suspend　the　functions　of　the　cells　without　damaging　them；　as　nitrous　oxid；　ether；　morphin。　Our　experiments　have　shown　that　the　brain…cell　changes　induced　by　drugs　of　the　first　class　are　precisely　the　same　as　the　cycle　of　changes　produced　by　the　emotions　and　by　physical　activity。　We　have　found　that　strychnin；　according　to　the　dosage；　causes　convulsions　ending　in　exhaustion　and　death；　excitation　followed　by　lassitude；　stimulation　without　notable　after…results；　or


｛illust。　caption　=　A；　Section　of　Cerebellum　of　Normal　Dog。　　C；　Section　of　Cerebellum　of　Dog　after　Repeated　Doses　of　Strychnin。　　FIG。　　37。　BRAIN…CELLS　SHOWING　STAGE　OF　HYPERCHROMATISM　FOLLOWED　BY　CHROMATOLYSIS　RESULTING　FROM　THE　CONTINUATION　OF　THE　STIMULUS。　　（Camera　lucida　drawings。）increased　mental　tone；　while　the　brain…cells　accurately　display　these　physiologic　alterations　in　proportional　hyperchromatism　in　the　active　stages；　and　proportional　chromatolysis　in　the　stages　of　reaction。　　The　biologic　and　therapeutic　application　of　this　fact　is　as　obvious　as　it　is　important。

In　our　experiments；　alcohol　in　large　and　repeated　dosage　caused　marked　morphologic　changes　in　the　brain…cells　which　went　as　far　even　as　the　destruction　of　some　of　the　cells　（Fig。　39）。　Ether；　on　the　other　hand；　even　after　five　hours　of　administration；　produced　no　observable　destructive　changes　in　the　brain…cells。

The　effect　of　iodoform　was　peculiarly　interesting；　as　it　was　the　only　drug　that　produced　a　rise　of　temperature。　　Its　observed　effect　upon　the　brain…cells　was　that　of　wide…spread　destruction。

Infections。In　every　observation　regarding　the　effect　of　pyogenic　infections　on　dogs　and　on　man　we　found　that　they　caused　definite　and　demonstrable　lesions　in　certain　cells　of　the　nervous　system；　the　most　marked　changes　being　in　the　cortex　and　the　cerebellum　（Fig。　40）。　For　example；　in　fatal　infections　resulting　from　bowel　obstruction；　in　peritonitis；　and　in　osteomyelitis；　the　real　lesion　is　in　the　brain…cells。　We　may；　therefore；　reasonably　conclude　that　the　lassitude；　the　diminished　mental　power；　the　excitability；　irritability；　restlessness；　delirium；　and　unconsciousness　which　may　be　associated　with　acute　infections；　are　due　to　physical　changes　in　the　brain…cells。

Graves'　Disease。In　Graves'　disease　the　brain…cells　show　marked　changes　which　are　apparently　the　same　as　those　produced　by　overwork；　by　the　emotions；　and　by　strychnin。　　In　the　postmortem　examination　of　one　advanced　case　it　was　found　that　a　large　number　of　brain…cells　were　disintegrated　beyond　the　power　of　recuperation；　even　had　the　patient　lived。　　This　is　undoubtedly　the　reason　why　a　severe　case　of　exophthalmic　goiter　sustains　a　permanent　loss　of　brain　power。

Insomnia。The　brains　of　rabbits　which　had　been　kept　awake　for　one　hundred　hours　showed　precisely　the　same　changes　as　those　shown　in　physical　fatigue；　strychnin　poisoning；　and　exhaustion　from　emotional　stimulation。　　Eight　hours　of　continuous　sleep　restored　all　the　cells　except　those　that　had　been　completely　exhausted。　This　will　explain　the　permanent　ill　effect　of　long…continued　insomnia；　that　is；　long…continued　insomnia　permanently　destroys　a　part　of　the　brain…cells　just　as　do　too　great　physical　exertion；　certain　drugs；　emotional　strain；　exophthalmic　goiter；　and　hemorrhage。　We　found；　however；　that　if；　instead　of　natural　sleep；　the　rabbits　were　placed　for　the　same　number　of　hours　under　nitrous　oxid　anesthesia；　not　only　did　the　brain…cells　recover　from　the　physical　deterioration；　but　that　90　per　cent。　　of　them　became　hyperchromatic。　This　gives　us　a　possible　clue　to　the　actual　chemical　effect　of　sleep。　For　since　nitrous　oxid　owes　its　anesthetic　effect　to　its　influence　upon　oxidation；　we　may　infer　that　sleep　also　retards　the　oxidation　of　the　cell　contents。　　If　this　be　true；　then　it　is　probable　that　inhalation　anesthetics　exert　their　peculiar　influence　upon　that　portion　of　the　brain　through　which　sleep　itself　is　produced。　If　nitrous　oxid　anesthesia　and　sleep　are　chemically　identical；　then　we　have　a　further　clue　to　one　of　the　primary　mechanisms　of　life　itself；　and　as　a　practical　corollary　one　might　be　able　to　produce　artificial　sleep　which　would　closely　resemble　normal　sleep；　but　which　would　have　this　advantage；　that　by　using　an　anesthetic　which　interferes　with　oxidation　the　brain…cells　might　be　reconstructed　after　physical　fatigue；　after　emotional　strain；　or　after　the　depression　of　disease。

In　the　case　of　the　rabbit　in　which　nitrous　oxid　was　substituted　for　sleep；　the　appearance　of　the　brain…cells　resembled　that　in　but　one　other　group　experimentally　examinedthe　brain…cells　of　hibernating　woodchucks。

Insanity。Our　researches　have　shown　that　in　the　course　of　a　fatal　disease　and　in　fatal　exhaustion；　however　produced；　death　does　not　ensue　until　there　is　marked　disorganization　of　the　brain　tissue。　In　the　progress　of　disease　or　exhaustion　one　may　see　in　different　patients　every　outward　manifestation　of　mental　deterioration；　manifestations　which；　in　a　person　who　does　not　show　any　other　sign　of　physical　disease；　mark　him　as　insane。　　Take；　for　example；　the　progressive　mental　state　of　a　brilliant　scholar　suffering　from　typhoid　fever。　On　the　first　day　of　the　gradual　onset　of　the　disease　he　would　notice　that　his　mental　power　was　below　its　maximum　efficiency；　on　the　second　he　would　notice　a　further　deterioration；　and　so　the　mental　effect　of　his　disease　would　progress　until　he　would　find　it　impossible　to　express　a　thought　or　to　make　a　deduction。　No　one　can　be　philanthropic　with　jaundice；　no　one　suffering　from　Graves'　disease　can　be　generous；　no　mental　process　is　possible　in　the　course　of　the　acute　infectious　diseases。　　Just　prior　to　death　from　any　cause　every　one　is　in　a　mental　state　which；　if