Face memory and its disorders

Memory deficit in patients with cerebral small vessel disease: evidence from eye tracking technology

Cerebral small vessel disease is the one of the most prevalent causes of vascular cognitive impairment. We aimed to find objective and process-based indicators related to memory function to assist in the detection of memory impairment in patients with cerebral small vessel disease. Thirty-nine cerebral small vessel disease patients and 22 healthy controls were invited to complete neurological examinations, neuropsychological assessments, and eye tracking tasks. Eye tracking indicators were recorded and analyzed in combination with imaging features. The cerebral small vessel disease patients scored lower on traditional memory task and performed worse on eye tracking memory task performance compared to the healthy controls. The cerebral small vessel disease patients exhibited longer visit duration and more visit count within areas of interest and targets and decreased percentage value of total visit duration on target images to total visit duration on areas of interest during decoding stage among all levels. Our results demonstrated the cerebral small vessel disease patients performed worse in memory scale and eye tracking memory task, potentially due to their heightened attentional allocation to nontarget images during the retrieval stage. The eye tracking memory task could provide process-based indicators to be a beneficial complement to memory assessment and new insights into mechanism of memory impairment in cerebral small vessel disease patients.

Neural correlates of impaired learning and recognition of novel faces in mild cognitive impairment

OBJECTIVE

Face memory impairment significantly affects social interactions and daily functioning in individuals with mild cognitive impairment (MCI). While deficits in recognizing familiar faces among individuals with MCI have been reported, their ability to learn and recognize unfamiliar faces remains unclear. This study examined the behavioral performance and event-related potentials (ERPs) of unfamiliar face memorization and recognition in MCI.

METHODS

Fifteen individuals with MCI and 15 healthy controls learned and recognized 90 unfamiliar neutral faces. Their performance accuracy and cortical ERPs were compared between the two groups across the learning and recognition phases.

RESULTS

Individuals with MCI had lower accuracy in identifying newly learned faces than healthy controls. Moreover, individuals with MCI had reduced occipitotemporal N170 and central vertex positive potential responses during both the learning and recognition phases, suggesting impaired initial face processing and attentional resources allocation. Also, individuals with MCI had reduced central N200 and frontal P300 responses during the recognition phase, suggesting impaired later-stage face recognition and attention engagement.

CONCLUSION

These findings provide neurobehavioral evidence for impaired learning and recognition of unfamiliar faces in individuals with MCI.

SIGNIFICANCE

Individuals with MCI may have face memory deficits in both early-stage face processing and later-stage recognition .

Lesion-behaviour mapping reveals multifactorial neurocognitive processes in recognition memory for unfamiliar faces

Face recognition abilities, which play a critical role in social interactions, involve face processing and identifying familiar faces, but also remembering one-off encounters with previously unfamiliar faces. Previous functional imaging and lesion studies have found evidence for temporal, frontal, and parietal contributions to episodic recognition memory for previously unfamiliar faces. However, the functional contributions of these regions remain unclear. We, therefore, conducted a systematic group analysis of this memory function using lesion-behavior mapping. 95 first-event stroke patients (53 with right- and 42 with left-hemisphere damage) in the sub-acute phase performed the Wechsler Memory Scale (WMS-III) face recognition memory subtest. We analyzed their performance relative to 75 healthy controls, using signal detection measures. To identify brain lesions specifically implicated in face recognition deficits, we used voxel-based lesion-behavior mapping (VLBM; an analysis comparing the performance of participants with and without damage affecting a given voxel). Behavioral analysis disclosed a pronounced impairment in the performance of patients with right hemisphere damage. Frontal damage was associated with an increased amount of false alarms (i.e., failed rejection of new face items) and overly liberal criterion setting, without affecting the recognition of studied faces. In contrast, parietal damage was associated with impaired recognition of studied faces, which was more pronounced in immediate than in delayed retrieval. These findings suggest the existence of multifactorial neurocognitive processes in recognition memory for unfamiliar faces.

Signal-detection analysis of the WMS faces subtest: Results in amyotrophic lateral sclerosis patients

About 30% of patients with amyotrophic lateral sclerosis (ALS) suffer from cognitive impairment and 10-15% suffer from frontotemporal dementia (FTD). Due to the patients' reduced motor function, a neuropsychological assessment with a low motor demand can be an advantage when evaluating patients, aiding its application. The present work has studied the usefulness of the Faces subtest of the Wechsler Memory Scale in 42 patients with ALS and 42 healthy volunteers applying Holdnack's Two-High Threshold model. The ALS group performed significantly worse in immediate and delayed discriminability. With respect to the presence of cognitive impairment, it seemed to be independent of the indexes proposed by Holdnack and Delis. On the other hand, motor problems were associated with delayed recognition while behavior alterations were linked to problems with delayed discriminability. ALS patients do not express differences in the bias index, in line with other types of previously studied pathologies.

Wechsler Memory Scale-III Faces test performance in patients with mild cognitive impairment and mild Alzheimer's disease

Little is known about the sensitivity of the Wechsler Memory Scale-Third Edition (WMS-III) Faces subtest to memory impairment associated with mild cognitive impairment (MCI). In this study, Faces performance was examined in 24 MCI patients, 46 mild Alzheimer's disease (AD) patients, and 98 elderly controls. We hypothesized that participants with diagnoses of MCI or AD would be impaired relative to controls on Faces. Analyses showed that AD participants performed significantly worse than MCI and intact participants, although there were no significant differences between MCI and intact participants. Data suggest that brain areas specialized for face recognition memory may be less affected by MCI and mild AD than regions specialized for verbal memory.

Orbitofrontal and hippocampal contributions to memory for face-name associations: the rewarding power of a smile

Memory processes can be enhanced by reward, and social signals such a smiling face can be rewarding to humans. Using event-related functional MRI (fMRI), we investigated the rewarding effect of a simple smile during the encoding and retrieval of face-name associations. During encoding, participants viewed smiling or neutral faces, each paired with a name, and during retrieval, only names were presented, and participants retrieved the associated facial expressions. Successful memory activity of face-name associations was identified by comparing remembered vs. forgotten trials during both encoding and retrieval, and the effect of a smile was identified by comparing successful memory trials for smiling vs. neutral faces. The study yielded three main findings. First, behavioral results showed that the retrieval of face-name associations was more accurate and faster for smiling than neutral faces. Second, the orbitofrontal cortex and the hippocampus showed successful encoding and retrieval activations, which were greater for smiling than neutral faces. Third, functional connectivity between the orbitofrontal cortex and the hippocampus during successful encoding and retrieval was stronger for smiling than neutral faces. As a part of the reward system, the orbitofrontal cortex may modulate memory processes of face-name associations mediated by the hippocampus. Interestingly, the effect of a smile during retrieval was found even though only names were presented as retrieval cues, suggesting that the effect was mediated by face imagery. Taken together, the results demonstrate how rewarding social signals from a smiling face can enhance relational memory for face-name associations.

Relationship between chronic pain and cognition in cognitively intact older persons and in patients with Alzheimer's disease. The need to control for mood

BACKGROUND

Brain areas that are involved in cognition and mood also play a role in pain processing.

OBJECTIVE

The goal of the present study was to examine the relationship between chronic pain and cognition [executive functions (EF) and memory], while controlling for mood, in cognitively intact older persons and in patients with Alzheimer's disease (AD).

METHODS

Two groups of subjects participated: 20 older persons without dementia and 19 patients in an early stage of probable AD who suffered from arthrosis/arthritis. Pain intensity and pain affect were assessed by the Colored Analogue Scale for Pain Intensity and for Pain Affect, the Faces Pain Scale (FPS) and the Number of Words Chosen-Affective (NWC-A). Level of depression and anxiety were evaluated by questionnaires. EF and memory were assessed by neuropsychological tests.

RESULTS

The results show that significant correlations between specific cognitive functions, pain intensity and pain affect were lacking in the cognitively intact older persons. Cognition, in particular memory, appeared to be related to depressive symptoms. In contrast, a significant positive correlation was observed between EF, pain intensity and pain affect measured by the FPS in the AD group.

CONCLUSIONS

Although older persons with depression were excluded, in studies on pain and cognition one should control for the presence of depressive symptoms in older persons with and without dementia.

Cognitive changes in Parkinson's disease patients with visual hallucinations

OBJECTIVE

To evaluate the decline in specific neuropsychological functions in nondemented Parkinson's disease (PD) patients with a history of visual hallucinations (VH).

METHODS

Twenty PD patients with VH, 20 PD patients without VH and 18 normal controls were followed up over a 1-year period and assessed for cognitive decline.

RESULTS

Forty-five percent of nondemented hallucinating PD patients developed dementia during the 1-year period between baseline and follow-up evaluations. Of the nondemented hallucinating PD patients nearly 70% showed impairment in multiple cognitive domains. The progressive decline in hallucinating PD patients affected mainly visual memory for faces and visuoperceptive-visuospatial functions.

CONCLUSION

Our results support a fast impairment of complex visual functions in hallucinating PD patients, but also a progressive decline in multiple cognitive domains, which have been identified as a risk of developing dementia in PD.

The importance of impaired physical health and age in normal cognitive aging

The objective of this study was to investigate the importance of impaired physical health and age in normal cognitive aging. In our cross-sectional, clinical and explorative study, medical and neuropsychological data from 118 voluntary healthy controls aged 26-91 years were collected from five recruitment occasions. Health was assessed according to a criterion reflecting clinical and subclinical severity. The examinations included a clinical investigation, brain neuroimaging, and a comprehensive neuropsychological assessment. Regression analyses showed a significant incidence of clinical and subclinical medical disorders that explained 10.8% of the variation in cognitive performance, while age-related impairment explained 5.6%. Findings of the central nervous system were important but various other medical findings explained about half of the health-related variation. Cognitively demanding tasks were more susceptible to impaired physical health while tasks comprising salient motor- and visual spatial elements were more prone to be impaired by age. Our findings suggest (1) that impaired physical health is more important than chronological age in accounting for cognitive impairment across the adult lifespan, (2) that age and health dissociate with regard to cognitive functions affected, and (3) that selection for so-called "super healthy" elderly people might be justified in cognitive research. Because the prevalent diseases in normal aging are potentially preventable, the present findings promise good prospect for prevention of future cognitive disability among elderly people.

Neural responses to facial expression and face identity in the monkey amygdala

The amygdala is purported to play an important role in face processing, yet the specificity of its activation to face stimuli and the relative contribution of identity and expression to its activation are unknown. In the current study, neural activity in the amygdala was recorded as monkeys passively viewed images of monkey faces, human faces, and objects on a computer monitor. Comparable proportions of neurons responded selectively to images from each category. Neural responses to monkey faces were further examined to determine whether face identity or facial expression drove the face-selective responses. The majority of these neurons (64%) responded both to identity and facial expression, suggesting that these parameters are processed jointly in the amygdala. Large fractions of neurons, however, showed pure identity-selective or expression-selective responses. Neurons were selective for a particular facial expression by either increasing or decreasing their firing rate compared with the firing rates elicited by the other expressions. Responses to appeasing faces were often marked by significant decreases of firing rates, whereas responses to threatening faces were strongly associated with increased firing rate. Thus global activation in the amygdala might be larger to threatening faces than to neutral or appeasing faces.

Bilateral hippocampal volume predicts verbal memory function in temporal lobe epilepsy

The present study used quantitative volume estimates of the hippocampus based on structural magnetic resonance imaging (MRI) to predict memory performance of individuals with epilepsy of temporal lobe origin (TLE). Twenty individuals with TLE completed standardized neuropsychological tests and a quality of life inventory, and participated in a brain MRI protocol designed to obtain high-resolution images of the hippocampus. The combined volume of the left and right hippocampi was found to be the best predictor of objective verbal memory performance. This finding is consistent with the functional adequacy model of hippocampal function. In contrast, the asymmetry between right and left hippocampal volume was the best predictor of subjective ratings of cognitive functioning, which is consistent with the functional reserve model. The collective and complementary functions of the left and right hippocampi merit further exploration in prospective studies of memory function and TLE.