Recognition Memory In Patients Research Articles

Features of event-related potentials during retrieval of episodic memory in patients with mild cognitive impairment due to Alzheimer's disease.

To provide a rigorous comparison between patients with mild cognitive impairment due to Alzheimer's disease (MCI-AD) and healthy elderly, as well as to assess the value of electroencephalography (EEG) in terms of early diagnosis, we conducted a neutral image recognition memory task involving individuals with positive biomarkers including β amyloid deposition, pathologic tau or neurodegeneration. The task involving study and test blocks was designed to evaluate participants' recognition memory. Electroencephalogram was recorded synchronously to elicit event-related potentials in patients with MCI-AD and healthy control subjects. We further analyzed differences between groups or conditions in terms of behavioral performance, time domain, and time-frequency domain. The MCI-AD cohort showed a slower response time to old/new images and had low accuracy regarding behavioral performance. The amplitude of the late positive complex for the old/new effects was significantly suppressed in the MCI-AD cohort when compared with that in the HC cohort. The amplitude of the late old/new effects was correlated with the Auditory Verbal Learning Test recognition score in all participants. The time-frequency domain analysis revealed that correct recognition of old items elicited a decrease in beta power, mainly limited to the HC cohort. Moreover, the combination of behavioral (processing speed and accuracy) and electrophysiological (average amplitude and relative power of delta band) measures contributes to classifying patients with MCI-AD from healthy elderly people. Changes of old/new effects, accuracy and response time are sensitive to the impairment of recognition memory in patients with MCI-AD and have moderate value in predicting the incipient stage of AD.

Transcutaneous Vagus Nerve Stimulation Does Not Affect Verbal Memory Performance in Healthy Volunteers.

IntroductionInvasive vagus nerve stimulation (VNS) improves word recognition memory in patients with epilepsy. Recent studies with transcutaneous VNS (tVNS) have also shown positive effects on various subdomains of cognitive functioning in healthy volunteers. In this randomized, controlled, crossover study, we investigated the effect of tVNS on a word recognition memory paradigm in healthy volunteers to further investigate the potential of tVNS in the treatment of cognitive disorders.MethodsWe included 41 healthy participants aged between 18 and 30 years (young age group) and 24 healthy participants aged between 45 and 80 years (older age group). Each participant completed a word recognition memory paradigm during three different conditions: true tVNS, sham, and control. During true tVNS, stimulation was delivered at the cymba conchae. Sham stimulation was delivered by stimulating the earlobe. In the control condition, no stimulation was given. In each condition, participants were asked to remember highlighted words from three test paragraphs. Accuracy scores were calculated for immediate recall after each test paragraph and for delayed recognition at the end of the paradigm. We hypothesized that highlighted words from paragraphs in the true tVNS condition would be more accurately recalled and/or recognized compared to highlighted words from paragraphs in the sham or control condition.ResultsIn this randomized study, tVNS did not affect the accuracy scores for immediate recall or delayed recognition in both age groups. The younger group showed significantly higher accuracy scores than the older group. The accuracy scores improved over time, and the most recently learned words were better recognized. Participants rated true tVNS as significantly more painful; however, pain was not found to affect accuracy scores.ConclusionIn this study, tVNS did not affect verbal memory performance in healthy volunteers. Our results could not replicate the positive effects of invasive VNS on word recognition memory in epilepsy patients. Future research with the aim of improving cognitive function should focus on the rational identification of optimized and individualized stimulation settings primarily in patients with cognitive deficits.

18 Recall deficits with preserved recognition memory in limbic encephalitis

Objective Limbic Encephalitis (LE) is an inflammatory neurological disorder of the medial temporal lobe that causes a memory syndrome. LE with Voltage-Gated Potassium-Channel Complex (VGKC-LE) antibodies preferentially affects the hippocampus: neuro-imaging and post-mortem studies demonstrate hippocampal inflammation with relative sparing of the Para-hippocampal gyrus and other brain areas. Behaviourally, a syndrome is produced characterised by long-term memory impairment, seizures and behavioural disturbances. This patient group allows assessment of the specific role of the hippocampus in recall and recognition memory as well as in other aspects of cognition. Our aim was to characterise this in more detail than has been done before. Method We report a study of seven patients with immunologically proven VGKC-LE in which we have carried out a systematic study of cognition including verbal and visual delayed recall and recognition. Each patient was matched by age, gender and IQ with two controls. We assessed pre-morbid intelligence [WTAR], general intelligence [short-form WAIS III], semantic memory [Graded Naming Test], visual perception [VOSP], executive function [Letter and Category Fluency: Trails and Colour-Word interference from [DK-EFS; Hayling-Brixton], memory [AMIPB and Warrington Recognition Memory; Doors and People], autobiographical memory [AMI] and emotion [DASS-21]. Results We found consistent and significant deficits in delayed verbal and visual recall but not in recognition memory in patients with VGKC-LE. The autobiographical memory interview showed a dissociation between their personal semantic schedule (unimpaired) and autobiographical incident memory, which was impaired. Patients had low immediate and delayed story recall scores as compared to control participants. There were no other significant differences in neuropsychological testing. Conclusion This unique patient group can provide insights into the role of the hippocampus in various brain processes. Our work supports models based on a critical hippocampal role in recall but not recognition memory. Ongoing work is further characterising the memory phenotype and its correlation with structural changes in the medial temporal lobe.

32. Event-related potential correlates of word recognition memory in patients with coronary artery disease

The relationship between left ventricular ejection fraction (LVEF) and cognitive performance in patients with coronary artery disease (CAD) without overt heart failure is still under debate. In the present study we combine behavioural measures and event-related potentials (ERPs) to verify whether electrophysiological correlates of recognition memory (Old/New effect) is modulated differently as a function of LVEF. Twenty-five male patients with CAD (13 without [LVEF > 55%] and 12 with [LVEF < 40%] left ventricular dysfunction), and a Mini Mental State Examination score > 25 were enrolled. ERPs were recorded while participants performed a visual word recognition task consisting of a test phase in which they were asked to judge whether visual stimuli were previously presented in a learning phase (‘old’) or not (‘new’). ERPs responses from the test phase were analyzed. A late positive ERP component between 300 and 500 ms was differentially modulated in the two groups: a clear old/new effect (enhanced mean amplitude for old respect to new items) was observed in patients without LVEF dysfunction; whereas patients with overt LVEF dysfunction did not show such old/new effect. These data suggest that ERPs may reveal possible functional brain abnormalities that might be not observed at behavioural levels.

When recognition memory is independent of hippocampal function.

Hippocampal damage has been thought to result in broad memory impairment. Recent studies in humans, however, have raised the possibility that recognition memory for faces might be spared. In five experiments we investigated face recognition in patients with hippocampal lesions (H) or large medial temporal lobe (MTL) lesions, including patients where neurohistological information was available. Recognition of novel faces was unequivocally intact in H patients but only at a short retention interval. Recognition memory for words, buildings, inverted faces, and famous faces was impaired. For MTL patients, recognition memory was impaired for all materials and across all retention intervals. These results indicate that structures other than the hippocampus, perhaps the perirhinal cortex, can support face recognition memory in H patients under some conditions. The fact that the faces were novel when recognition memory was intact does not fully account for our findings. We propose that the role of the hippocampus in recognition memory is related to how recognition decisions are accomplished. In typical recognition tasks, participants proceed by forming an association between a study item and the study list, and the recognition decision is later made based on whether participants believe the item was on the study list. We suggest that face recognition is an exception to this principle and that, at short retention intervals, participants can make their recognition decisions without making explicit reference to the study list. Important features of faces that might make face recognition exceptional are that they are processed holistically and are difficult to verbally label.

Relational memory and hippocampal function in psychotic bipolar disorder.

Recent cognitive, genetic, and histological studies have highlighted significant overlap between psychotic bipolar disorder and schizophrenia. Specifically, both bipolar disorder and schizophrenia are characterized by interneuron dysfunction within the hippocampus, an essential structure for relational memory. Relational memory impairments are a common feature of schizophrenia, but have yet to be investigated in psychotic bipolar disorder. Here, we tested the hypothesis that psychotic bipolar disorder is characterized by relational memory deficits. We used a transitive inference (TI) paradigm, previously employed to quantify relational memory deficits in schizophrenia, to assess relational memory performance in 17 patients with psychotic bipolar disorder and 22 demographically matched control participants. Functional magnetic resonance imaging was used to examine hippocampal activity during recognition memory in patients and controls. Hippocampal volumes were assessed by manual segmentation. In contrast to our hypothesis, we found similar TI performance, hippocampal volume, and hippocampal recruitment during recognition memory in both groups. Both psychotic bipolar disorder patients and controls exhibited a positive correlation between hippocampal volume and relational memory performance. These data indicate that relational memory impairments are not a shared feature of non-affective and affective psychosis.

Improving delayed face recognition in Alzheimer's disease by differential outcomes.

Previous studies have demonstrated the benefit of the differential outcomes procedure (DOP) in human learning. In the present study we aimed to explore whether the DOP might also help to overcome the face recognition memory deficit commonly observed in Alzheimer's disease (AD) patients. A delayed matching-to-sample task was used. Participants were instructed to choose which of the 4 alternative faces (comparison stimuli) matched the previously seen face (sample stimulus). Either short (5 seconds) or long (25 seconds) delays were interposed between the sample and the comparison stimuli. In the differential outcomes condition each sample face was paired with its own outcome. In contrast, in the nondifferential condition, outcomes were randomly arranged. The differential outcomes effect (DOE) was evident in the AD patients with both accuracy and latency data. That is, they showed a significantly better and faster delayed face recognition when differential outcomes were arranged. The analyses also revealed a significant main effect of delay; participants were slower in the 25 seconds condition than in the 5 seconds condition, but the difference was higher in the patients than in the controls. These findings demonstrate, to our knowledge for the first time, that face recognition memory in patients with Alzheimer is improved when differential outcomes are used and draw attention to the potential of this procedure as a therapeutic technique.

Catechol-O-methyltransferase Val158Met association with parahippocampal physiology during memory encoding in schizophrenia

Catechol-O-methyltransferase (COMT) Val158Met has been associated with activity of the mesial temporal lobe during episodic memory and it may weakly increase risk for schizophrenia. However, how this variant affects parahippocampal and hippocampal physiology when dopamine transmission is perturbed is unclear. The aim of the present study was to compare the effects of the COMT Val158Met genotype on parahippocampal and hippocampal physiology during encoding of recognition memory in patients with schizophrenia and in healthy subjects. Using blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI), we studied 28 patients with schizophrenia and 33 healthy subjects matched for a series of sociodemographic and genetic variables while they performed a recognition memory task. We found that healthy subjects had greater parahippocampal and hippocampal activity during memory encoding compared to patients with schizophrenia. We also found different activity of the parahippocampal region between healthy subjects and patients with schizophrenia as a function of the COMT genotype, in that the predicted COMT Met allele dose effect had an opposite direction in controls and patients. Our results demonstrate a COMT Val158Met genotype by diagnosis interaction in parahippocampal activity during memory encoding and may suggest that modulation of dopamine signaling interacts with other disease-related processes in determining the phenotype of parahippocampal physiology in schizophrenia.

Performance in recognition memory is correlated with entorhinal/perirhinal interictal metabolism in temporal lobe epilepsy

In addition to the hippocampus, the entorhinal/perirhinal cortices are often involved in temporal lobe epilepsy (TLE). It has been proposed that these anterior parahippocampal structures play a key role in recognition memory. We studied the voxel-based PET correlation between number of correctly recognized targets in a new recognition memory paradigm and interictal cerebral metabolic rate for glucose, in 15 patients with TLE with hippocampal sclerosis. In comparison to healthy subjects, patients had decreased recognition of targets ( P < 0.001) and ipsilateral hypometabolism (relative to side of hippocampal sclerosis) of the hippocampus, entorhinal/perirhinal cortices, medial temporal pole, and middle temporal gyrus ( P < 0.05, corrected by false discovery rate method). Performance correlated with interictal metabolism of ipsilateral entorhinal/perirhinal cortices ( P < 0.005, Spearman's rank test), but this relationship was not significant in the hippocampus itself ( P > 0.18, Spearman's rank test). These findings highlight the preferential involvement of entorhinal/perirhinal cortices in recognition memory in patients with TLE, and suggest that recognition memory paradigms may be useful in assessing anterior parahippocampal functional status in TLE.

Compensatory brain activation for recognition memory in patients with medication-resistant epilepsy

Progressive decline of memory functions has been observed in patients with chronic medication-resistant epilepsy. The progression likely relates to the effects of epileptiform discharges, seizures, and medications on the processes of encoding and retrieval. The goal of the study described here was to use functional MRI (fMRI) to examine the effects of chronic epilepsy on verbal recognition memory. We enrolled 12 patients with medication-resistant epilepsy (5 with right and 7 with left hemispheric seizure onset) and 18 healthy controls matched for age, gender, and handedness. Subjects underwent fMRI at 3T using a word recognition task during which they had to recall if words presented during scanning were words they had learned prior to scanning. Although we noted many similarities in the fMRI activation patterns between the subjects with epilepsy and the healthy subjects in areas typically involved in memory processing, testing of the interaction effects for target-foil differences between groups revealed several differences in activation including the right insula, the left cuneus, and the bilateral subgenual anterior cingulate cortex (ACC). In patients with epilepsy, these regions exhibited greater activation for targets than foils, but in healthy subjects the difference was reversed (right insula), absent (left cuneus), or included deactivation to target words (pregenual ACC). These differences were seen despite similar performance during the memory task, suggesting that activations observed in these additional regions may represent compensatory processes for verbal recognition memory that are induced by chronic brain injury related to recurrent seizures.

Sex differences in face recognition memory in patients with temporal lobe epilepsy, patients with generalized epilepsy, and healthy controls

The influence of sex on face recognition memory was studied in 49 patients with temporal lobe epilepsy, 20 patients with generalized epilepsy, and 32 healthy controls. After learning 20 faces, serially presented for 5 seconds each, subjects had to recognize the 20 among 40 faces (including 20 new faces) immediately and 24 hours later. Women had better face recognition than men, with no significant differences between groups. Women’s advantage was due mainly to superior delayed recognition. Taken together, the results suggest that sex has a similar impact on face recognition in patients with epilepsy and healthy controls, and that testing delayed face recognition raises sensitivity for sex differences. The influence of sex on face recognition in patients with epilepsy should be acknowledged when evaluating individuals or comparing groups.

Variability in the Impairment of Recognition Memory in Patients with Frontal Lobe Lesions

Fourteen patients with frontal lobe lesions and 14 normal subjects were tested on a recognition memory task that required discriminating between target words, new words that are synonyms of the targets and unrelated distractors. A deficit was found in 12 of the patients. Moreover, three different patterns of recognition impairment were identified: (I) poor memory for targets, (II) normal hits but increased false recognitions for both types of distractors, (III) normal hit rates, but increased false recognitions for synonyms only. Differences in terms of location of the damage and behavioral characteristics between these subgroups were examined. An encoding deficit was proposed to explain the performance of patients in subgroup I. The behavioral patterns of the patients in subgroups II and III could be interpreted as deficient post- retrieval verification processes and an inability to recollect item-specific information, respectively.

Impaired odor recognition memory in patients with hippocampal lesions

In humans, impaired recognition memory following lesions thought to be limited to the hippocampal region has been demonstrated for a wide variety of tasks. However, the importance of the human hippocampus for olfactory recognition memory has scarcely been explored. We evaluated the ability of memory-impaired patients with damage thought to be limited to the hippocampal region to recognize a list of odors. The patients were significantly impaired after a retention delay of 1 h. Olfactory sensitivity was intact. This finding is in agreement with earlier reports that rats with hippocampal lesions exhibited memory impairment on an odor delayed nonmatching to sample task (after 30 min and 1 h) and that patients with damage thought to be limited to the hippocampal region were impaired on an odor span memory task. Olfactory recognition memory, similar to recognition memory in other sensory modalities, depends on the integrity of the hippocampal region.

Levels of processing effects on recognition memory in patients with schizophrenia

This study sought to characterize the performance of patients with schizophrenia, as compared with healthy participants, on a memory task that required encoding of items to different depths. Participants included 21 individuals with schizophrenia and 26 healthy controls. During the encoding phase of the study, participants processed successively presented words in two ways: perceptually (by making a decision as to whether the letter “a” was present in the word) or semantically (by making a living/nonliving decision for each word). During the recognition phase of the study, participants were presented with a list of words containing items that had been presented during the encoding phase (during either the letter decision task or the semantic decision task), as well as items that had not been seen before (foils). Though patients with schizophrenia performed more poorly overall on the recognition task, recognition was facilitated by semantic encoding to an equivalent degree in both groups. In other words, while significant main effects were present for group and encoding, no group×encoding condition was present. This result is consistent with previous findings of a lack of qualitative differences in performance on learning and memory tasks between patients with schizophrenia and healthy controls. It also suggests that strategies that place constraints on the encoding processes used by patients may help improve the efficiency with which they learn and remember information.

Recognition memory of serially or simultaneously presented words or figures, of epilepsy patients with or without mesial temporal sclerosis

Previous studies, examining short-term recognition memory in patients with partial seizures as a consequence of mesial temporal sclerosis (MTS) have reported inconsistent findings. Dependent on the paradigms used for measuring recognition memory, some studies have demonstrated that the mesial temporal structures are not critically involved in short-term recognition memory. In addition, other studies found a lateralization effect that is consistent with the generally accepted association between left temporal lobe lesions and verbal memory deficits, and right temporal lobe lesions and non-verbal memory impairments. In the present study verbal and non-verbal recognition memory was tested in 41 patients with left or right temporal lobe epilepsy with MTS (22 left; 19 right) versus 44 patients with left or right temporal lobe epilepsy but without MTS (28 left; 16 right). Verbal and non-verbal recognition tasks were presented in both a serial and simultaneous condition to test a hypothesized local/global paradigm. Multiple analyses of variance (MANOVA) showed that unilateral MTS has no marked effects on verbal or non-verbal recognition memory of patients with seizures. An interaction effect between MTS and the lateralization of epileptic activity was found on memory performance: MTS only leads to deficits in recognition memory in patients with right-sided epileptiform activity. As hypothesized, patients with left temporal lobe abnormalities, have specific deficits with recognizing serially presented information.

Olfactory short-term memory and related amygdala recordings in patients with temporal lobe epilepsy.

Olfactory short-term recognition memory was assessed with a delayed odour-matching task in 38 patients with unilateral temporal lobe epilepsy (TLE) and stereotactic electroencephalography (SEEG) recordings taken prior to surgical treatment. The amygdala SEEG activity associated with odorant stimulation was examined in 18 patients. Because the invasive SEEG procedure is only performed in a clinical framework, electrophysiological data obtained from these patients could not be analysed in comparison with data obtained from control subjects. Behavioural results (hits, false alarms, discrimination, bias scores) showed global impairment of odour recognition memory in patients when compared with controls. We also found lower discrimination and higher false alarm scores in left than in right TLE patients, and higher false alarm scores in male than in female patients. The hemisphere effect is discussed in terms of psychosocial trait differences between patients. Electrophysiological recordings collected from the amygdala demonstrated that odorant stimulation was associated with chemosensory evoked potentials (CSEPs). Analysis revealed that CSEPs obtained for target odorants had lower peak amplitudes and latencies than those obtained in response to sample odorants. The reduced peak amplitudes suggest a mechanism of repetition suppression--a process assumed to reflect neural activity related to high-level cognitive processes such as attention, memory and decision making. Latency modulations appear rather to be linked to early stages of information processing and may therefore reflect a facilitation process due to selective attention.

Neural basis of novel and well-learned recognition memory in schizophrenia: a positron emission tomography study.

The level of familiarity of a given stimulus plays an important role in memory processing. Indeed, the novelty/familiarity of learned material has been proven to affect the pattern of activations during recognition memory tasks. We used visually presented words to investigate the neural basis of recognition memory for relatively novel and familiar stimuli in schizophrenia. Subjects were 34 healthy volunteers and 19 schizophrenia spectrum patients. Two experimental cognitive conditions were used: 1 week and again 1 day prior to the PET imaging subjects had to thoroughly learn a list of 18 words (well-learned memory). Subjects were also asked to learn another set of 18 words presented 1 min before the PET experiment (novel memory). During the PET session, subjects had to recognize the list of 18 words among 22 new (distractor) words. Subjects also performed a control task (reading words). A nonparametric randomization test and a statistical t-mapping method were used to determine between- and within-group differences. In patients the recognition of novel material produced relatively less flow in several frontal areas, superior temporal gyrus, insular cortex, and parahippocampal areas, and relatively higher activity in parietal areas, visual cortex, and cerebellum, compared to controls. No significant differences in flow were seen when comparing well-learned memory activations between groups. These results suggest that different neural pathways are engaged during novel recognition memory in patients with schizophrenia compared to healthy individuals. During recognition of novel material, patients failed to activate frontal/limbic regions, recruiting a set of posterior perceptual brain regions instead.

Neural correlates of recognition memory with and without recollection in patients with Alzheimer's disease and healthy controls

To dissociate recognition memory with and without recollection, event-related potentials (ERPs) of patients with Alzheimer's disease (AD) and matched controls were recorded in a test of verbal recognition memory accompanied by a source judgement. AD patients who had smaller hippocampi showed a disability to recollect the study context (source). Their ERPs elicited by correctly recognized old words compared to new items were more positive only between 300 and 500 ms with a maximum over the frontal scalp. Controls exhibited a sustained old/new effect over left temporoparietal and frontal sites. The present findings suggest that preserved recognition memory in patients with mild AD is independent of hippocampally mediated processes recollecting episodic memories.

Recall and recognition memory in patients with focal frontal, temporal lobe and diencephalic lesions

Patients with frontal, temporal lobe, or diencephalic lesions were compared with healthy controls on measures of recall and recognition memory for word lists. Exposure times were titrated to match recognition memory scores 30 s after the end of word-list presentation as closely as possible. Using this technique, we failed to find a disproportionate impairment in recall memory in either the frontal lobe lesion patients or in the amnesic (temporal lobe and diencephalic) patients, compared with healthy controls. Consistent with this finding, performance on these tasks showed highly significant correlations with anterograde memory quotients (despite the titration procedure), but not with executive\\frontal function tasks. On the other hand, the frontal lobe lesion group showed disproportionate benefit in the recall of semantically categorised words, compared with unrelated words. This may indicate an impairment in retrieval or access, compared with the amnesic (temporal lobe and diencephalic) patients, and\\or an inability to organise their learning of unrelated words spontaneously, compared with healthy controls.

Impaired recognition memory in patients with lesions limited to the hippocampal formation.

Impaired recognition memory in patients with lesions limited to the hippocampal formation.