Biomedical subjects

L S Cermak

Publications and source records attributed to L S Cermak.

At least 19 recordsLinked to original sources

PubMed2000

Long-term retention of transient news events.

Many retrospective analyses of remote memory have demonstrated recency effects in that memory for events proximal to the time of testing is superior to memory for events from remote time periods. However, the rate at which information decays over time and the specific pattern of forgetting may vary depending upon the distinct attributes of stimuli used as indices of memory. Studies examining long-term forgetting of well rehearsed, conceptually integrated information underscore preservation of remote events, some of which are thought to be permanently stored in memory. A different pattern of forgetting emerges in relation to recall of discrete facts whereby recall declines according to a negatively accelerated decay curve. In the current study long-term retention of transient news events was examined. Results were examined in relation to the effects of age and sex. All age groups demonstrated recency effects in that events from the recent past were recalled better than remote events. Age did not exert a negative influence on recall of remote or recent events with the exception of younger participants who did not recall items predating their dates of birth. Older female participants were less adept at recalling very old events than their male counterparts.

Adult↗

PubMed2000

Role of perceptual and organizational factors in amnesics' recall of the Rey-Osterrieth complex figure: a comparison of three amnesic groups.

To examine the contribution of visual-perceptual and visual-organizational factors to visual memory in amnesia, Korsakoff, medial temporal, and anterior communicating artery (ACoA) aneurysm amnesics' copy, organization, and recall performance on the Rey-Osterrieth Complex Figure was assessed. Korsakoff patients were matched to medial temporal patients in terms of severity of amnesia, while the ACoA group, which was less severely amnesic, was matched to the Korsakoff patients on performance on executive tasks. Results indicated that while both the ACoA and Korsakoff groups had poorer copy accuracy and organization than controls, only the Korsakoff patients' copy accuracy was worse than the other two amnesic groups. While the Korsakoff patient's visuoperceptual deficits could partially explain this group's poor performance at immediate recall, the Korsakoff group's comparatively worse performance at delayed recall could not be accounted for by poor copy accuracy, reduced visual organization, or even the combined influence of these two factors.

Adult↗

PubMed1999

The effects of divided attention during encoding and retrieval on amnesic patients' memory performance.

This study examined the effect of divided attention during encoding or retrieval on primary (recall) or secondary (button-pressing) task performance by amnesic patients and control subjects. Experiment 1 demonstrated that control subjects' recall was affected by divided attention during encoding but not during retrieval, while the amnesic patients' recall remained at the same low level for all conditions. Both groups showed a reduction in rate of button-pressing during encoding relative to their baseline levels and a further reduction during the retrieval interval. In Experiment 2, five learning trials, instead of just one, were presented. This acted to increase all subjects' recall and also had the effect of producing superior recall following free encoding relative to encoding during divided attention for the amnesic patients as well as for the control subjects. Button-pressing performance during the encoding interval increased to baseline for both groups during the five presentation trials, but there was no increase in the rate of button-pressing during the retrieval interval. Amnesic patients' normal attention to the primary task during encoding and retrieval was felt to have several implications for future neuroimaging tasks with these patients.

Aged↗

PubMed1999

Perceptual fluency as a cue for recognition judgments in amnesia.

This study investigated the extent to which amnesic patients use fluency of perceptual identification as a cue for recognition. Perceptual fluency was measured by having participants gradually unmask words before making recognition judgments. In Experiment 1, familiarity was the only possible basis for recognition because no words had been presented in the study phase. In Experiment 2, recollection provided an alternative basis for recognition because words had appeared in the study phase. Amnesic patients were as likely as normal controls to use perceptual fluency as a cue for recognition in Experiment 1 but were more likely than controls to do so in Experiment 2. For both groups, perceptual fluency affected judgments for studied and unstudied items to the same extent in Experiment 2. These findings suggest that amnesic patients do use perceptual fluency cues, but reliance on perceptual fluency does not necessarily elevate recognition accuracy.

Amnesia↗

PubMed1998

Intact temporal memory in amnesic patients.

Current theories propose that amnesia is caused by an inability to encode the temporal properties of recent events and/or to associate information across time. The present investigation tested this postulation by manipulating the recency effect which is theorized to be caused by the encoding of temporal information. The continual-distractor paradigm was used to vary the temporal properties of recently presented lists. Amnesics' recall responded normally to the temporal manipulations in lists ranging from 18-54 s. In contrast, overall recall was impaired compared to normals in all conditions and across all positions, including the final position. These findings dissociate memory for temporal information from overall levels of recall. They suggest that the amnesic patient's memory deficit is not caused by an inability to encode temporally associated information.

Aged↗

PubMed1998

Amnesic patients' impaired category exemplar production priming.

This study examined the effect of varying the number of potential target words on amnesic patients' category exemplar production performance. In Experiment 1, 4 words from each of 6 categories were presented to amnesic patients and normal control participants. This was followed by an indirect task in which each participant produced the first 8 words that came to mind when presented with a category cue. On this task the amnesic patients were impaired. This outcome stands in sharp contrast to most other category exemplar production tasks that have been reported. However, these other paradigms tend to restrict participants' processing during target item presentation while our procedure allowed them to analyze the target words as they chose. Our procedure may have allowed the control participant more opportunity to "cluster" target words from the same category during list presentation and this, in turn, may have given them an advantage at the time of category exemplar production. Therefore, in Experiment 2, only 1 word per category was presented in the target list and only 2 words per category were requested during category exemplar production. Surprisingly, the amnesic patients still exhibited impaired performance. Therefore, it was suggested that perhaps amnesic patients' known inability to perform semantic levels of processing during individual target word presentation may have resulted in impaired priming for categorical features for these patients.

Amnesia, Retrograde↗

PubMed1998

Effects of spacing and repetition on amnesic patients' performance during perceptual identification, stem completion, and category exemplar production.

The effects of repetition and spacing of repetitions on amnesic patients' implicit task performance was studied. Amnesic patients and control participants performed a perceptual identification task, a word-stem completion task, and a category exemplar production task after the presentation of target words repeated within a list. Repetition proved to have no effect on perceptual identification or on word-stem completion, but it did play a role in category exemplar production. As expected, the amnesic patients demonstrated normal performance on the perceptual identification and word-stem completion tasks. However, on category exemplar production, the amnesic patients' performance was significantly below that of the control participants, and the 2 groups differentially responded to repetition. The normal control participants' spontaneous ability to analyze semantic features of words led to unconscious priming of the category and its links to the exemplars after only one presentation of a word. Amnesic patients, on the other hand, seemed to rely more on the fluency produced by multiple presentations.

Aged↗

PubMed1997

Unconscious influences on amnesics' word-stem completion.

Amnesic patients and control subjects were asked to complete three-letter word-stems under one of three retrieval conditions. In a direct condition, they were told to use the stems as retrieval cues for words that had just been presented in a study list. In an indirect condition, they were told to use the first word that came to mind with no reference made to the study list. Finally, in an oppositional condition, they were told to use the first word that came to mind unless it had appeared on the study list. During the study list presentation, the patients and controls had analyzed each word according to either semantic (associating to each word) or graphemic (counting letters with enclosed spaces) instructions. The results revealed that the control subjects produced a different number of study words during retrieval as a function of retrieval instructions and encoding condition. The amnesics, however, did not vary their performance as a function of retrieval instructions. Under all conditions, they completed the word-stems far more frequently with words from the study list than would be expected by chance and they consistently produced more semantic than graphemic responses. We concluded that semantic analysis might affect the fluency with which an item occurs for the amnesic, but that the item itself remains independent of the source of that fluency for these patients. Thus, the level of analysis performed on a word during study can affect the unconscious performance of amnesic patients but is unavailable for use during conscious retrieval.

Aged↗

PubMed1995

Comparison of figural intrusion errors in three amnesic subgroups.

To examine the contribution of memory deficits and executive dysfunction to the production of prior-item intrusion errors, Korsakoff, mesial temporal amnesic, and anterior communicating artery aneurysm (ACoA) patients' performance on the Visual Reproduction subtest of the Wechsler Memory Scale-Revised (WMS-R) was assessed. The Korsakoff patients were matched to the mesial temporal group in terms of severity of amnesia, while the ACoA group, which was less severely amnesic, was matched to the Korsakoff group in their performance on executive tests. Results indicated that at immediate recall, Korsakoff patients made significantly more intrusions than mesial temporal and ACoA patients. Conversely, after a delay, ACoA patients tended to make more intrusions than the other groups. Findings suggest that intrusions are due to a combination of deficient memory and executive dysfunction. A further comparison of a subgroup of ACoA patients matched to the Korsakoff patients in terms of severity of amnesia, however, revealed differences in the pattern of intrusions of these two groups, suggesting that different mechanisms may underlie Korsakoff and ACoA patients' susceptibility to interference.

Adult↗

PubMed1995

Intact delay-eyeblink classical conditioning in amnesia.

The status of classical conditioning in human amnesia was examined by comparing conditioning of the eyeblink response (the unconditional response) to a tone conditioned stimulus (CS) paired with an airpuff unconditioned stimulus (US) in the delay paradigm between 7 amnesic and 7 age- and education-matched normal control participants. Amnesic patients exhibited normal baseline performance in pseudoconditioning and normal acquisition and extinction of conditioned responses in terms of the number, latency, and magnitude of eyeblinks. These results indicate that in humans, as in rabbits, brain structures critical for declarative memory are not essential for the acquisition of elementary CS-US associations.

Adult↗

PubMed1995

Impaired delay eyeblink conditioning in amnesic Korsakoff's patients and recovered alcoholics.

The performance of amnesic Korsakoff patients in delay eyeblink classical conditioning was compared with that of recovered chronic alcoholic subjects and healthy normal control subjects. Normal control subjects exhibited acquisition of conditioned responses (CRs) to a previously neutral, conditioned tone stimulus (CS) following repeated pairings with an unconditioned air-puff stimulus, and demonstrated extinction of CRs when the CS was subsequently presented alone. Both amnesic Korsakoff patients and recovered chronic alcoholic subjects demonstrated an impairment in their ability to acquire CRs. These results indicate that the preservation of delay eyeblink conditioning in amnesia must depend on the underlying neuropathology of the amnesic syndrome. It is known that patients with amnesia caused by medial temporal lobe pathology have preserved conditioning. We have now demonstrated that patients with amnesia caused by Korsakoff's syndrome, as well as recovered chronic alcoholic subjects, have impaired conditioning. This impairment is most likely caused by cerebellar deterioration resulting from years of alcohol abuse.

Aged↗

PubMed1994

Acquisition of generic memory in amnesia.

Amnesic patients' ability to acquire generic, semantic information was assessed relative to their own level of episodic memory. Patients studied a list of words in which some items were presented twice and others once. Upon each presentation, the words were tagged episodically by presenting them in a unique color. Recall of the colors in which words were presented suggested that individual presentations of repeated items were less likely to be recalled than presentations of nonrepeated items; however, actual recall of repeated items exceeded that of nonrepeated items. This outcome demonstrated that amnesics can recall some items generically without recalling either of their individual presentations. However, amnesics' recall of twice-presented items remained far below that of the control group, even when their recall of once-presented items was matched by testing the control group after a delay. This finding suggests that amnesic patients can acquire new generic knowledge but do so much less efficiently than do normal individuals. Furthermore, this deficit occurs independently of the amnesics' episodic memory impairments, reflecting instead a disruption in semantic learning per se.

Adult↗

PubMed1993

Episodic effects on picture identification for alcoholic Korsakoff patients.

Experience with degraded pictures produces better subsequent identification of these pictures in amnesic patients. To examine the contribution of episodic memory to this facilitation, we compared identification of pictures that were identical to a studied picture, pictures that shared the same name with a studied picture, and new, unstudied pictures. In an initial phase of the experiment, patients clarified each picture until they could name it. During a second phase, they again clarified each picture and judged whether it was identical, similar (same-name), or different from pictures identified in the first phase. Korsakoff patients, as well as alcoholic controls, identified identical pictures faster than same-name pictures, and these in turn were identified faster than new pictures. The Korsakoff patients did show less facilitation than the alcoholic controls, but this difference was eliminated by testing the alcoholics after a week delay. The smaller facilitation in performance shown by amnesics and by alcoholics tested after a delay was accompanied by impaired recognition memory as well as by qualitative differences in recognition performance. The Korsakoff patients tended to label same-name pictures as different while alcoholic controls tested immediately called them identical, a tendency which disappeared when alcoholics were tested after a delay. These findings suggest that Korsakoff patients are influenced by specific episodic information even more than are alcoholic controls.

Aged↗

PubMed1992

Fluency versus conscious recollection in the word completion performance of amnesic patients.

To examine the relative contribution of fluency and recollection to the word completion performance of amnesics, we administered a task in which patients were told specifically not to utilize previously presented words during stem completion (an Exclusion condition). This condition was contrasted with a standard word completion task in which patients were encouraged simply to complete the stem with the first word that came to mind (an Inclusion condition). Since the exclusion condition necessitated controlled respecification of the initial presentation, it was hypothesized that amnesics would be less able than controls to exclude study list items. Consistent with this hypothesis, the results indicated that the amnesics' performance, unlike that of the alcoholic controls, did not significantly differ as a function of task condition. To examine whether amnesics' conscious recollection could be enhanced, Experiment 2 presented the study list five times. The amnesics now were able to exclude a significant number of items from the study list; however, they still did so considerably less frequently than alcoholic controls. For the alcoholic controls, increasing the number of study trials had little additional effect on their exclusion performance, but it significantly enhanced their inclusion performance. Taken together, these findings suggest that for control subjects, word completion performance is likely mediated by a combination of fluency and recollection, while for amnesic patients, performance is almost exclusively based on the fluency with which an item comes to mind.

Alcohol Amnestic Disorder↗

PubMed1992

Priming of spatial configurations in alcoholic Korsakoff's amnesia.

To examine priming for novel, nonverbal patterns, a modification of the paradigm used by Gabrieli et al. (1990, Neuropsychologia, 28, 417-427) was administered to a group of Korsakoff patients, a group of alcoholic controls, and a group of normal controls. Subjects were asked to connect five-dot configurations into the first pattern that came to mind. Priming was than assessed by having the subjects copy experimenter-provided interpretations for each configuration and examining the effect of this manipulation on the subjects' subsequent interpretation of the same configurations. For the Korsakoff patients, the copied prime replaced their initial perceptual interpretation less frequently than it did for normal controls. Instead, the prime had its effect by combining with the baseline percept. These findings suggest that priming for novel, nonverbal material is weaker and less direct for Korsakoff patients than it is for controls.

Aged↗

PubMed1992

The dissociation of anterograde and retrograde amnesia in a patient with herpes encephalitis.

Establishing the precise relationship between anterograde amnesia (AA) and retrograde amnesia (RA) has implications for psychological and neuroanatomical models of memory. Many patients have been described who demonstrate AA in conjunction with RA or who demonstrate AA with little, or no apparent, RA. Intact anterograde memory in conjunction with deficits on tasks of retrograde memory is rarely encountered. In this paper, we describe a young female patient (LD) whose RA is extremely severe when contrasted with her mild to moderate deficits on tasks of verbal anterograde memory. In addition, on tests of episodic and semantic autobiographical memory, LD appeared more impaired in her recall of specific episodes than of factual information about her past. The importance of this dissociation in RA for the episodic-semantic distinction and the possible role of visual imagery in recalling remote episodic events are discussed.

Adult↗

PubMed1991

A further analysis of perceptual identification priming in alcoholic Korsakoff patients.

Alcoholic Korsakoff patients have been shown to have normal repetition priming for words, but impaired priming for pseudowords, on perceptual identification tasks. Because real words, but not pseudowords, have semantic representations, successful priming of real words has been attributed to semantic activation. Alternatively, however, priming might reflect the perceptual, i.e. orthographic and phonological familiarity associated with real words in comparison with pseudowords. In order to examine which of these factors accounts for normal priming by amnesics, Experiment 1 was designed to contrast perceptual identification priming for words, pseudowords and pseudohomonyms (e.g. "phaire"). On this task, Korsakoff patients showed normal priming for real words and for pseudohomonyms, but significantly impaired priming for pseudowords. It was felt that since pseudohomonyms are orthographically unfamiliar but could access semantics through their phonological route, activation of a semantic representation rather than perceptual familiarity might be the critical factor underlying successful priming. Experiment 2 was then designed to further explore the robustness of this semantically mediated priming by presenting different word types within the same study list. Under these conditions, Korsakoffs' pseudohomonym priming was consistently below normal. This suggests that priming in Korsakoff patients depends upon the conceptual salience of the stimuli and not solely on semantic activation.

Alcohol Amnestic Disorder↗

PubMed1991

Repetition effects in a lexical decision task: the role of episodic memory in the performance of alcoholic Korsakoff patients.

To examine the contribution of episodic memory to the successful verbal priming performance of Korsakoff patients, we adapted a lexical decision task which holds constant the processing demands during study and testing. Words and nonwords were repeated at a lag of 0, 1, 3, 8 and 15 items and the decrease in response latency was taken as a measure of priming. In Experiment 1, Korsakoff patients showed repetition priming of a magnitude similar to that obtained by alcoholic controls, even at a lag of 15 intervening items. Experiment 2 explored the effect of word frequency on repetition priming. Korsakoff patients again showed normal priming up to lags of 15, and, as expected, these repetition effects were larger for low frequency than for high frequency words. This outcome was felt to be more consistent with an episodically based familiarity account than with a semantic activation account. Finally, Korsakoff patients were found to be impaired in their ability to use episodic memory in an explicit memory task that used the same material under comparable presentation conditions (Experiment 3). Contemporary processing models of episodic memory are discussed as possible explanations for the successful implicit memory performance by amnesic patients on this task.

Adult↗