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The neuronal basis for consciousness

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Theneuronalbasisforconsciousness

R.Llinas,U.Ribary,D.ContrerasandC.PedroarenaDepartmentofPhysiologyandNeuroscience,NewYorkUniversitySchoolofMedicine,550FirstAvenue,NewYork,NY10016,USA

Attemptingtounderstandhowthebrain,asawhole,mightbeorganizedseems,forthe¢rsttime,tobeaserioustopicofinquiry.Oneaspectofitsneuronalorganizationthatseemsparticularlycentraltoglobalfunctionistherichthalamocorticalinterconnectivity,andmostparticularlythereciprocalnatureofthethalamocorticalneuronalloopfunction.Moreover,theinteractionbetweenthespeci¢candnon-speci¢cthalamicloopssuggeststhatratherthanagateintothebrain,thethalamusrepresentsahubfromwhichanysiteinthecortexcancommunicatewithanyothersuchsiteorsites.Thegoalofthispaperistoexplorethebasicassumptionthatlarge-scale,temporalcoincidenceofspeci¢candnon-speci¢cthalamicactivitygeneratesthefunctionalstatesthatcharacterizehumancognition.Keywords:consciousness;thalamocortical;gammaoscillations;facilitation;coincidencedetection;voltagesensitivedye

1.INTRODUCTIONPerhapsoneofthemostinsightfuldiscussionsrelatingtothenatureofglobalbrainfunctiontookplaceinEnglandinthe¢rstdecadesofthiscenturybetweenCharlesS.Sherrington(1906)andT.GrahamBrown(1915).Theformerproposed,onthebasisofanimalphysiologicalexperimentation,thatthespinalcordoperated,funda-mentally,asasetofcomplexre£exes.Indeed,thisviewfollowedtheJamesianpostulateofre£ex(James1890),inwhichthenervoussystemisorganizedasasetofcomplexneuronalconnectivitypathwaystriggeredintoactionbytheoutsideworld.Onthisview,behaviourisfundamen-tallytheresultantofsensoryinput.ThisgeneralpostulatecontrastedwiththepointofviewespousedbyGrahamBrown(1914,1915)andmorerecentlybyNicholasBern-stein(1967),whoviewedspinalcordfunctionasmostlyorganizedasintrinsicallygeneratedneuronalactivity.Withthisviewsensoryinputsaremostlymodi¢ersofsuchintrinsicactivity.Brownworked,asdidSherrington,onthespinalcordbutmorespeci¢callyonlocomotion.Hewasthe¢rsttodemonstratethatlocomotionwasstillsupportedbythespinalcordafterbilateraldorsalrootdea¡erentation,resultinginthetotalremovalofsensoryinput(Brown1914).Onthatbasis,heproposedthatthecomplexmotoroutputrequiredforlocomotionisapropertyofthespontaneousactivityoftheneuronalcircuitsinthespinalcordandbrainstem.Interestingly,suchimportantobservationandconclusionhavebeenmostlyignoredbypresent-dayneuroscience,whichcontinuestoemphasizetheprimordialimportanceofsensoryinputinmotororganization.Likewise,incognitivephysiologytheprevailingviewtodayisthatconsciousnessismostlytheresultantofsensoryinputbroughtintothebrainbythedi¡erentsensorya¡erents,theactivityofwhichrepresentthefunctionalbasisforcognition.2.COGNITIONASANINTRINSICFUNCTIONALSTATEOFTHEBRAINWeproposehere,aswehavedoneonpastoccasions(Llinas1990),thatconsciousness,likelocomotion,mightbemoreacaseofintrinsicactivitythanofsensorydrive.Thus,ithasbeenproposedthatconsciousnessisanoneiric-likeinternalfunctionalstatemodulated,ratherthangenerated,bythesenses(Llinas&Pare1991).Wemayrememberhowinchildhoodthesoundofacurtain£utteringinthedarkcouldevokeratherworryingimagesthatwereimmediatelydispelledbyturningonthelights.Andso,theinternaleventsthatweknowasthinking,imaginingorrememberingare,forthemostpart,relatedtointrinsicactivity.Thisisofcourseverymuchinaccordancewiththefactthataverylargepercentageoftheconnectivityinthebrainisrecurrentandthatmuchofitsactivityisrelatedtosuchintrinsicconnectivitynotnecessarilyrelatedtotheimmediacyofsensoryinput.Perhapsthemostspectaculardi¡erenceconcerningglobalbrainstatesisthatbetweenwakefulnessanddreamlesssleep.Weallrecognizethatnogrossmorpholo-gicalchangesoccurinourbrainsduringsleep,thatcouldexplaintheenormousdisparitybetweenthetwostates.Indeed,thedi¡erencemustbefunctional.Weknowfullwellthatifwearetiredwecanfallasleepextraordinarilyquicklyandthatifweareasleepandastrongstimulusisgiventous(e.g.thehavocplayedbyanalarmclock)wecanawakenalsoextraordinarilyfast.Itissofast,indeed,thattheonlysubstratecapableofsupportingthespeedofthesetwoeventsmustbeelectricalinnaturegiventhelargenumberofelementsinvolved;electricalinthesenseoftheelectricalactivityofneuronsandthesynapticinputthatinitiateorterminatesuchactivity.Thequestionswouldthenbe:(i)whatisthefunda-mentaldi¡erencebetweenbeingawakeandbeingasleep?and(ii)whatdoesittellusaboutbrainfunction?Itseemstousthattheseareamongthemostimportant

Phil.Trans.R.Soc.Lond.B(1998)353,1841^18491841&1998TheRoyal

Societycluesaboutthenatureofconsciousness.The¢rstconclusiontobedrawnfromsuchinferenceisthatconsciousness(i.e.beingawakeandabletofeel,judgeandremember)isbutonefunctionalstateofourbrain.Otherstates,suchasbeingasleep,donotsupportconsciousnessoreventhefeelingofself-existence.Fromclassicalneurologyweknowthatdamagetothecerebralcortexinmammalscancauseavarietyofwell-de¢neddysfunctionalconditionsorsyndromes.Visualcortexdamageisaccompaniedbyblindnessthatcanbeofdi¡erenttypesdependingonthepreciselocationofthecorticalinsult.Similar¢ndingsarealsoencounteredinothercorticalstructures.Thus,damagetotheauditory,thesomatosensory,themotorandpre-motorcorticesareaccompaniedbywell-de¢nedconditions.Infact,the¢rstsuchneurologicallesiontobedescribedinthetermsusedabovewasthatwhichfollowsdamageofBroca'sarea,generatingdysarthria.Giventheabove,wetendtoequateconsciousnesswithcorticalfunctionmoreorlessexclusively,ignoringthefactthatthenervoussystemisdeeplycursiveandthatastrictlyhierarchicalorganization,ratherthanaglobalorder,ismostunlikely.Ontheassumptionthatconscious-nessisaglobalfunctionalstateofthebrainrelatingtomorethancorticalactivity,weshallnowattempttode¢nethefunctionalparametersthatsupportandgenerateconsciousness.

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新的125个科学问题

新的125个科学问题

新的125个科学问题

2005年，在庆祝创刊125周年之际，Science公布了125个最具挑战性的科学问题，对指引近十几年的科学发展产生积极影响。

16年之后的2021年，随着科学的不断突破，许多问题得到一定程度的解答，一些问题也更加深入。彼时，上海交通大学携手Science杂志发布了“新125个科学问题”——《125个科学问题：探索与发现》。

此次发布的问题包括数学、化学、医学与健康、生命科学、天文学、物理学、信息科学、工程与材料科学、神经科学、生态学、能源科学与人工智能等领域。除了“物质的起源是什么”“黎曼猜想是真的吗”“地球上有多少物种”等科学家始终在追问的问题，还有一些有趣的问题也将带来面向人类未来的科学探究，例如：为什么我们会坠入爱河？人类有一天会不得不离开地球吗？人类为什么会对猫狗如此着迷？

此次科学问题征集结合国际前沿、全球共需、科学发展，聚焦前瞻重大科学问题，面向科学家、学生、社会征集。世界顶尖科学家协会也发挥资源优势，邀请诺贝尔奖、沃尔夫奖、拉斯克奖、图灵奖、麦克阿瑟天才奖等世界“最强大脑”共同参与，共同讨论人类当前与未来面对的科学问题。

SJTU & Science 125个科学问题

Mathematical Sciences 数学

1. What makes prime numbers so special?

1.什么使素数如此特别？

2. Will the Navier–Stokes problem ever be solved?

2.纳维尔-斯托克斯问题会得到解决吗？

3. Is the Riemann hypothesis true?

3.黎曼猜想是真的吗？

Chemistry

1. Are there more color pigments to discover?

1.还有更多色彩元素可发现吗？

2. Will the periodic table ever be complete?

人体奥秘第三集大脑的形成观后感

人体奥秘第三集大脑的形成观后感

人体奥秘第三集大脑的形成观后感

After watching the third episode of the documentary

series "The Mysterious Human Body" which focused on the

formation of the brain, I was left in awe of the complexity

and wonder of this incredible organ. The episode delved

into the intricate processes that take place during fetal

development, shedding light on the remarkable journey that

leads to the formation of the human brain.

One of the most fascinating aspects highlighted in the

episode was the sheer number of neurons that are formed

during the early stages of development. It is mind-boggling

to think that billions of neurons are generated within the

womb, each with the potential to connect and communicate

with other neurons in a highly intricate and precise manner.

This process of neuronal proliferation and migration is

复发性且MRI_阴性的LGI1_抗体相关脑炎一例

复发性且MRI_阴性的LGI1_抗体相关脑炎一例

2023年4月第54卷第4期294

综合病例研究新医学

复发性且MRI阴性的LGI1抗体相关脑炎一例

刘曈 夏丽萍 贾玉勤

【摘要】 富亮氨酸胶质瘤失活1蛋白（LGI1）抗体相关脑炎属于自身免疫性疾病，临床表现复杂多样，容易被误诊。该文报道1例LGI1抗体相关脑炎的74岁男性患者，其以意识丧失、四肢抽搐为首发症状，1年内发作2次，MRI检查未见明显异常信号，完善自身免疫性脑炎抗体检验，结果显示LGI1抗体血清及脑脊液抗体均（+）。确诊后

予糖皮质激素及免疫治疗，患者症状明显好转。【关键词】 富亮氨酸胶质瘤失活1蛋白；自身免疫性脑炎；临床表现；复发

A case report of recurrent and MRI negative LGI1 antibody-associated encephalitis Liu Tong△，Xia Liping，Jia Yuqin.△The First Clinical Medical College of Shandong University of Traditional Chinese Medicine， Jinan 250355， ChinaCorresponding author， Jia Yuqin， E-mail:**************【Abstract】 Leucine-rich glioma inactivated 1 （LGI1） antibody-associated encephalitis is an autoimmune disease with complex and diverse clinical manifestations and is prone to misdiagnosis. In this article， one case of LGI1 antibody-associated encephalitis was reported. This patient presented with loss of consciousness and limb twitches as the first symptoms， which occured twice within a year. No obvious abnormal signal was found by MRI. Autoimmune encephalitis antibody test showed that both serum and cerebrospinal fluid samples were positive for LGI1 antibody， which confirmed the diagnosis. Relevant symptoms were significantly improved after glucocorticoid use and immunotherapy.

各种脑区——精选推荐

各种脑区——精选推荐

各种脑区

Intraparietal sulcus (IPS): 顶间沟

The IPS contains a series of functionally distinct subregions that have been intensively investigated using both single cell

neurophysiology in primates and human functional neuroimaging.

Its principal functions are related to perceptual-motor coordination (for directing eye movements and reaching) and visual

attention.

The IPS is also thought to play a role in other functions, including processing symbolic numerical information, visuospatialworking memory and interpreting the intent of others.

Frontal Eye Fields (FEF)：前额眼区

The cortical area called frontal eye fields (FEF) plays an important role in the control of visual attention and eye movements.

Electrical stimulation in the FEF elicits saccadic eye movements. The FEF have a topographic structure and represents

saccade targets in retinotopic coordinates.