Squire neuropsychology of memory – documents anoxia refers to

Anr~ rev. Neurosci. 1982..~:241-273

THE NEUROPSYCHOLOGYOF HUMAN MEMORY

Larry R. Squire

Veterans administration medical center, san diego, california 92161 and thedepartment of psychiatry, university of california at san diego, school ofmedicine, la jolla, california 92093

INTRODUCTIONThe biology of memory s presently being nvestigated at a variety of levels

From he cellular to the neuropsychological. He nterdisciplinary nature ofneuroscience as encouraged he belief that superficially dissimilar phenom-ena–e.G, collateral sprouting, receptor adaptations, synaptic depressionand facilitation, dendritic growth n response o enriched environment, ndrecovery f function after brain injury–are all potentially relevant to ques-tions about memory ecause hey all reflect the nervous ystem’s capacityfor plasticity.Anoxia refers to


yet, a satisfying account of the biology of memory ustinclude not only information bout the details of synaptic change but alsoa description of the learning processes and memory ystems whose neurobi-

Olbgical mechanisms e wish to understand, plus information about howmemory s organized in the brain, how memory hanges with time, andwhich brain regions are involved.A favorable strategy for addressing these questions has been to studyamnesia. Most often, disorders of memory ccur in the context of impair-

Ment n other aspects of intellectual function, as in depression r dementia.Nonethdess, mnesia an occur as a relatively circumscribed isorder in theabsence of other cognitive impairment. As in many reas of biology wheredisorders of function have taught us about normal unction, so the analysisof memory isorders can provide insights into the structure and organiza-

anoxia refers to

*the US government as the right to retain a nonexdtmive, royalty-free license in and to

Any opyright overing his aper.

241

Www.Annualreviews.Org/aronline

Annual reviews

A n n u . R e v . N e u r o s c i . 1 9 8 2 . 5 : 2 4 1 – 2 7 3 . D o w n l o a d e d f r o m a r j o u r n a l s . A n n u a l r e v i e w s . O r g b y U n i v e r s i t y o f C a l i f o r n i a – S a n D i e g o o n 0 4 / 2 3 / 0 7 . F o r p e r s o n a l u s e o n l y .

242 squiretion of normal memory for other recent reviews, see piercy 1977, weis-krantz 1978, squire cohen 1982).This review considers four aspects of memory nd

Amnesiamanterogradeamnesia

Or loss of memory or events that occurred after the onset ofamnesia,

Retrograde amnesia

anoxia refers to

Or loss of premorbid memory,

Preserved learn-ing capacity,

And the

Anatomy of amnesia.

Each of these topics is organizedaround the specific issues that have guided the past decade of experimentalwork, with

The

Intention of summarizing what is presently known bout

The

Organization of memory nd its neurological substrate.THE amnesiasthe globally amnesic patient can appear norrnal to casual observation. Sucha patient may have normal intellectual capacity, normal digit span andintact social skills, and may retain knowledge cquired in early life. Thedefect lies in acquiring new memories and in recalling some memories hathad been acquired prior to becoming amnesic. This defect often occurs in

The

Absence of confabulation or confusion and with awareness by the patientof his condition.Anoxia refers to note that the amnesic syndrome has no connection tohysterical memory oss of psychogenic orgin. By far the most frequentlystudied example is found in korsakot~s syndrome. First described in 1887(korsakoff 1887), this syndrome has been studied extensively during thepast one hundred years (talland 1965, victor et al 1971, butters cermak1980). The disease develops after chronic alcohol abuse and is characterizedby symmetrical brain lesions along the walls of the third and fourth ventri-cles as well as in the cerebellum and cerebral cortex. After the acute stagehas passed, the patient with korsakoff syndrome s alert and responsive andhas normal intellectual capacity, as assessed by conventional tests.Anoxia refers to thedisease produces a spectrum of cognitive deficits, but amnesia occurs outof proportion to other neuropsychological findings.Additional information about global amnesia has come from the rareindividual case in which amnesia occurs as a strikingly circumscribed en-tity. The best-known and most thoroughly studied of these is case H. M.(scoville milner 1957). In 1953, H. M. Sustained bilateral resection of themedial temporal region in an attempt to relieve severe and intractableepilepsy. The resection included the anterior two-thirds of the hippocampalformation, parahippoeampal gyrus, amygdala, and uncus. Following sur-gery, H. M. Exhibited a profound amnesic syndrome in the absence of anydetectable change in general intellectual ability.Anoxia refers to H. M. Has been carefullystudied by brenda milner and her colleagues at the montreal neurologicalinstitute, and the findings from this case alone have provided an enormousamount of information about memory. A second well-studied patient is case

Www.Annualreviews.Org/aronline

Annual reviews

A n n u . R e v . N e u r o s c i . 1 9 8 2 . 5 : 2 4 1 – 2 7 3 . D o w n l o a d e d f r o m a r j o u r n a l s . A n n u a l r e v i e w s . O r g b y U n i v e r s i t y o f C a l i f o r n i a – S a n D i e g o o n 0 4 / 2 3 / 0 7 . F o r p e r s o n a l u s e o n l y .

HUMAN MEMORY 243N. A. (teuber et al 1968, kaushall et al 1981), who became amnesic in 1960following a penetrating brain injury with a miniature fencing foil.Anoxia refers to recentct scans have identified a lesion in the region of the left dorsomedialthalamie nucleus (squire moore 1979). Consistent with these radio-graphic findings, neuropsychological studies have demonstrated that theamnesia is more pronounced or verbal material than for nonverbal material(teuber et al 1968, squire slater 1978). For example, he forgets lists words and connected prose more eadily than faces or spatial locations. Inthis sense, N. A.’s memory eficit is material-specific, rather than global(milner 1968). Like the global amnesia of H. M., N. A.’s deficit occurs a bright individual (N. A.’s IQ is 124) without notable neuropsychologicalfindings other than amnesia.A final type of global amnesia s that produced y bilateral electroconvul-sive therapy (ECT) (squire 1981a).Anoxia refers to ECT s sometimes prescribed for treatment of depressive illness, and amnesia is its prominent side etfeet.Since ECT s a scheduled event, it is unique among he better studiedamnesias because it provides an opportunity to use each patient as his owncontrol in before-and-after studies. The amnesia recovers to some extentafter each treatment in a series and cumulates across treatments. Treat-ments are usually scheduled every other day, three times a week, and aseries of treatments typically consists of six to twelve treatments. By onehour after treatment, amnesia appears as a rather circumscribed deficit inthe absence of gross confusion or general intellectual impairment.The amnesias outlined above do not of course exhaust the list of causesor types of amnesia.Anoxia refers to for example, amnesia can also occur after head injury,anoxia, encephalitis, tumor, or vascular accident. But the amnesias de-scribed above have been studied the most extensively in recent years, partic-ularly from the point of view of the neuropsychology of memory.

ANTEROGRADE AMNESIA

Amnesia as a non-unitary disorder

Comparison f different amnesias dearly indicates that they do not all takethe same form. Moreover, some behavioral deficits ~exhibited by amnesicpatients have no necessary relationship to amnesia at all. This point can bemade most clearly by comparing the korsakoff syndrome o other examplesof amnesia. Thus, patients with korsakoff syndrome have cognitive andother clinical deficits not shared by other amnesic groups.Anoxia refers to these ndividualscommonly xhibit apathy, blandness, lethargic indifference, or vacuity ofexpression, loss of initiative, placidity (talland 1965, pp. 19, 29). Yet thereis no necessary relationship between amnesia and these features. Case N.A., for example, s energetic and alert, easily initiates social contact, and

Www.Annualreviews.Org/aronline

Annual reviews

A n n u . R e v . N e u r o s c i . 1 9 8 2 . 5 : 2 4 1 – 2 7 3 . D o w n l o a d e d f r o m a r j o u r n a l s . A n n u a l r e v i e w s . O r g b y U n i v e r s i t y o f C a l i f o r n i a – S a n D i e g o o n 0 4 / 2 3 / 0 7 . F o r p e r s o n a l u s e o n l y .

244 squireinteracts with people n an agreeable, friendly way kaushall t al 1981).Zangwill also has commented n the very different appearance f the kor-sakoff syndrome n comparison o the more pure anmesic syndromes…[possibly] involving the hippocampal egion (zangwill 1977).Anoxia refers to thus, thepatient with korsakoff yndrome erforms poorly on a variety of cognitivetests, such as those requiring rapid switching of strategies (talland 1965,

Oscar-berman 973, glosser et al 1976, butters cermak 980). Case H.M.’s amnesia, by comparison, s well circumscribed, and he performs wellon many uch tests (milner 1963, milner et al 1968).A particularly clear example of how he memory mpairment ssociatedwith the korsakoff yndrome s different from other examples f amnesiacomes rom a study of proactive interference. Proactive interference (PI)refers to the interfering effects of having earned a first task on the learningof a second ask. Like normal ubjects, patients with korsakoff yndromeexhibit a gradual decline in recall due o PI when earning successive roups

anoxia refers to

Of words hat all belong o the same category (e.G. Animal names). Normalsubjects, but not patients with korsakoff syndrome, xhibit an improve-ment n recall (or release from PI) when words are presented that belong

To a new category (e.G. Vegetable names) cermak t al 1974).Recently, these results have been placed in clearer perspective by thefinding that failure to release from PI is a sign of frontal lobe dysfunction,with no obligatory ink to amnesia moscovitch 981). Patients with materi-al-specific memory isorders (milner 1968), who ad sustained eft or rightunilateral temporal lobectomy, exhibited normal release from proactiveinhibition. Moreover, atients who had sustained surgical removal of por-tions of the frontal lobe, and who were not amnesic, ailed to release fromproactive inhibition.Anoxia refers to these indings suggest hat frontal lobe dysfunctiondetermines some of the features of the korsakoff syndrome. They alsoindicate the value of comparisons between amnesic groups for under-standing the nature of memory ysfunction. Clearly, generalizations aboutamnesia or the amnesic syndrome re not appropriate when peaking about

One kind of ananesia.A final example hat makes he same point comes rom studies of infor-mation-encoding by patients with korsakoff syndrome, case N. A., andpatients receiving ECT cermak reale 1978, wetzel squire 1980), orientation procedure was employed o assess how well these patients were

Capable of three kinds of encoding craik tulving 1975). By this proce-dure, encoding during learning is controlled by the experimenter hroughorienting questions that direct the subject’s attention to the superficialappearance f a word, to its sound, or to the semantic category to whichit belongs.Anoxia refers to on uch a task, normal ubjects exhibit superior recall of seman-

Tically encoded words. Case N. A. And patients receiving ECT xhibited the

Www.Annualreviews.Org/aronline

Annual reviews

A n n u . R e v . N e u r o s c i . 1 9 8 2 . 5 : 2 4 1 – 2 7 3 . D o w n l o a d e d f r o m a r j o u r n a l s . A n n u a l r e v i e w s . O r g b y U n i v e r s i t y o f C a l i f o r n i a – S a n D i e g o o n 0 4 / 2 3 / 0 7 . F o r p e r s o n a l u s e o n l y .