Karl Lashley 538267 219018868 2008-06-13T05:32:56Z Sural 5066418 {{Infobox Scientist |name = Karl Spencer Lashley |box_width = |image =Replace_this_image_male.svg |image_width =150px |caption = Karl Spencer Lashley |birth_date = [[June 7]], [[1890]] |birth_place = [[Davis, West Virginia]] |death_date = [[August 7]], [[1958]] |death_place = |residence = |citizenship = |nationality = [[United States]] |ethnicity = |field = [[psychology]] |work_institutions = |alma_mater = [[Johns Hopkins University]] |doctoral_advisor = |doctoral_students = |known_for = [[learning]] and [[memory]] |author_abbrev_bot = |author_abbrev_zoo = |influences = |influenced = |prizes = |religion = |footnotes = |signature = }} '''Karl Spencer Lashley''' ([[1890]]–[[1958]]), born in [[Davis, West Virginia]], was an American [[psychologist]] and [[behaviorist]] well-remembered for his influential contributions to the study of [[learning]] and [[memory]]. His failure to find a single [[biology|biological]] locus of memory (or "[[Engram (neuropsychology)|engram]]", as he called it) suggested to him that memories were not localized to one part of the [[brain]], but were widely distributed throughout the [[Cerebral cortex|cortex]]. While working toward his Ph.D. in genetics at [[Johns Hopkins University]], Karl Lashley became associated with the influential psychologist [[John B. Watson]]. During three years of [[postdoctoral]] work on [[vertebrate]] behavior (1914-17), he began formulating the research program that was to occupy the remainder of his life. In 1920 he became an assistant professor of psychology at the [[University of Minnesota]], [[Minneapolis]], where his prolific research on brain function gained him a professorship in 1924. He was later a professor at the [[University of Chicago]] (1929-35) and [[Harvard University]] (1935-55) and also served as director of the Yerkes Laboratories of Primate Biology, [[Orange Park, Florida]] from 1942 to 1955. His work included research on brain mechanisms related to sense receptors and on the cortical basis of motor activities. His major work was done on the measurement of behavior before and after specific, carefully quantified, induced cortical damage in rats. He trained rats to perform specific tasks (seeking a food reward), then lesioned varying portions of the rat cortex, either before or after the animals received the training depending upon the experiment. The amount of cortical tissue removed had specific effects on acquisition and retention of knowledge, but the location of the removed cortex had no effect on the rats' performance in the maze. This led Lashley to conclude that memories are not localized but widely distributed across the cortex.Today we know that distribution of engrams does in fact exist, however, the distribution is not equal across all cortical areas, as Lashley assumed. His study of the V1 (primary visual cortex) led him to believe that it was a site of learning and memory storage (i.e an [[engram]]) in the brain. He reached this erroneous conclusion due to imperfect lesioning methods. By 1950, Lashley had distilled his research into two theories. The principle of "[[Mass Action Principle (neuroscience)|mass action]]" stated that the cerebral cortex acts as one—as a whole—in many types of learning. The principle of "[[equipotentiality]]" stated that if certain parts of the brain are damaged, other parts of the brain may take on the role of the damaged portion. == Notable publications == *1923 "The [[behavioristic]] interpretation of consciousness." ''Psychological Bulletin'' *1929 "Brain mechanisms and intelligence." *[[1930]] "Basic [[neural]] mechanisms in behavior." ''Psychological Review'' *1951 "The problem of serial order in behavior." ''Cerebral Mechanisms in Behavior'' ==References== *{{Citation |id = [[PMID]]:12115784 |url= http://www.ncbi.nlm.nih.gov/pubmed/12115784 |id = [[PMID]]:12115785 |url= http://www.ncbi.nlm.nih.gov/pubmed/12115785 |last=Dewsbury |first=Donald A |publication-date=2002 |year=[[2002]] |title=Constructing representations of Karl Spencer Lashley. |volume=38 |issue=3 |periodical=Journal of the history of the behavioral sciences |pages=225-45 |doi = 10.1002/jhbs.10060 }} *{{Citation |id = [[PMID]]:11894885 |url= http://www.ncbi.nlm.nih.gov/pubmed/11894885 |last=Dewsbury |first=D A |publication-date=2002 Feb |year=[[2002]] |title=The Chicago Five: a family group of integrative psychobiologists. |volume=5 |issue=1 |periodical=History of psychology |pages=16-37 }} *{{Citation |id = [[PMID]]:10693270 |url= http://www.ncbi.nlm.nih.gov/pubmed/10693270 |last=Sapetskiĭ |first=A O |publication-date= |year= |title=[A physiologist's dialog with a psychologist] |volume=49 |issue=6 |periodical=Zhurnal vyssheĭ nervnoĭ deiatelnosti imeni I P Pavlova |pages=909-18 }} *{{Citation |id = [[PMID]]:3511136 |url= http://www.ncbi.nlm.nih.gov/pubmed/3511136 |last=Bruce |first=D |publication-date=1986 Jan |year=[[1986]] |title=Lashley's shift from bacteriology to neuropsychology, 1910-1917, and the influence of Jennings, Watson, and Franz. |volume=22 |issue=1 |periodical=Journal of the history of the behavioral sciences |pages=27-44 }} *{{Citation |id = [[PMID]]:4941968 |url= http://www.ncbi.nlm.nih.gov/pubmed/4941968 |last=Roofe |first=P G |publication-date=1970 Jan |year=[[1970]] |title=Some letters from the Herrick-Lashley correspondence. |volume=8 |issue=1 |periodical=Neuropsychologia |pages=3-12 }} *{{Citation |id = [[PMID]]:13658968 |url= http://www.ncbi.nlm.nih.gov/pubmed/13658968 |last=CARMICHAEL |first=L |publication-date=1959 May 22 |year=[[1959]] |title=Karl Spencer Lashley, experimental psychologist. |volume=129 |issue=3360 |periodical=[[Science (journal)|Science]] |pages=1410-2 }} *{{Citation |id = [[PMID]]:13590401 |url= http://www.ncbi.nlm.nih.gov/pubmed/13590401 |last=WALSHE |first=F M |publication-date=1958 Nov |year=[[1958]] |title=Karl S. Lashley. |volume=8 |issue=11 |periodical=Neurology |pages=870 }} *{{Citation |id = [[PMID]]:12115785 |url= http://www.ncbi.nlm.nih.gov/pubmed/12115785 |id = [[PMID]]:12115784 |url= http://www.ncbi.nlm.nih.gov/pubmed/12115784 |last=Weidman |first=Nadine |publication-date=2002 |year=[[2002]] |title=The depoliticization of Karl Lashley: A response to Dewsbury. |volume=38 |issue=3 |periodical=Journal of the history of the behavioral sciences |pages=247-53; discussion 255-7 |doi = 10.1002/jhbs.10061 }} ==See also== *[[Sequence learning]] *[[Engram (neuropsychology)]] *[http://www.gfai.de/~heinz/publications/lectures/2007_kreuth_abstract.htm Holographic properties found in interference networks] {{DEFAULTSORT:Lashley, Karl}} [[Category:1890 births]] [[Category:1958 deaths]] [[Category:American psychologists]] [[Category:Johns Hopkins University alumni]] [[Category:Animal testing]] {{US-psychologist-stub}} [[de:Karl Lashley]] [[es:Karl Lashley]] [[nl:Karl Lashley]] [[ja:カール・ラシュレー]]