The regulation of neovascularization of matrix metalloproteinases and their inhibitors

This study sought to produce a cognitive profile of herpes simplex encephalitis (HSE) survivors from a large group of definitively diagnosed, acyclovir-treated participants. Results from 22 adults who underwent a battery of neuropsychological tests indicated anterograde memory dysfunction to be the most severe and common deficit (although the variation was great), with less severe and less frequent impairments in the areas of retrograde memory, executive functions, and language functioning. Overall, neuropsychological outcome was unimpaired in six participants, mildly impaired in thirteen, moderately impaired in one, severely impaired in two. Older participants and those with a lower level of consciousness before the start of treatment produced poorer scores on certain aspects of cognitive outcome (p < 0.05). A significantly better cognitive outcome was found in participants for whom there was a short delay (fewer than 5 days) between symptom onset and acyclovir treatment compared with those participants for whom there was a longer delay. The two children in the study had disparate results on most tests, the exception being those assessing memory functioning on which both children had scores at population norms. On a naming task designed to explore category-specific knowledge deficits, the adults as a group made more errors on pictures of living things than nonliving things (matched pair-wise for word frequency and visual familiarity), although this difference disappeared on a smaller subset of pictures also matched for visual complexity.     

Primary progressive semantic aphasia: a case study

A longitudinal case study of a patient with a progressive loss of meaning of objects with preserved phonology and syntax is presented. Repeated measures of language, praxis, visual cognition, and semantic processing were carried out. The patient still has preserved conversational speech, social skills, and orientation in her 8th year of her illness, but shows severe anomia and comprehension deficit in all modalities of stimulus presentation. In addition to standardized tests of language, cognition, and memory, specific experiments of categorization, modalities of word access, item consistency, category specificity, and definition of words were carried out. Results indicate a frequency dependent loss of meaning that was consistent in all modalities and throughout all object categories. However, the relative preservation of visual categorization of all categories tested and the language based categorization of animals suggested some fractionation of semantic memory. Relative preservation of autobiographical and personal memories versus semantic memory was a striking observation. Evidence for selective impairment of central semantic processing was obtained from experiments indicating item consistency of loss and the lack of semantic cuing. Neuroimaging evidence of left temporal lobe atrophy and the classical picture is compatible with similar cases published under the term semantic dementia or "transcortical sensory aphasia with visual agnosia" and suggest the diagnosis of Pick's disease.     

Associative visual agnosia resulting from a disconnection between intact visual memory and semantic systems

We report the case of a patient (RC) who developed a severe visual agnosia, associated to alexia without agraphia, color anomia and amnesia, following an ischemic stroke in the territory supplied by the left posterior cerebral artery. Based on his proficient performance on tests evaluating analysis of elementary visual features, formation of viewer-centered and object-centered representations of visual stimuli and discrimination between drawings representing real and unreal objects, we concluded that the critical locus of deficit was a disconnection between the normally functioning visual memory store and the semantic system. RC's disturbance in visual processing of human faces paralleled his recognition disorder of other classes of objects. The possible contribution of neurobiological factors in determining RC's agnosic deficit is discussed.     

Questioning the Living/Nonliving Dichotomy: Evidence From a Patient With an Unusual Semantic Dissociation.

In this article the authors describe a patient (J.P.) whose category-specific naming deficit eluded the classical dichotomies between living versus nonliving items or visual versus functional attributes. At age 22, he had herpes simplex encephalitis followed by a left temporal lobectomy. J.P. was tested on measures of visual perception, category naming, fluency, and name-picture matching. He showed a severe impairment naming and identifying fruits, vegetables, and musical instruments. His performance with animals and birds was spared inconsistently, meaning that even the preserved categories were, at some point, affected. J.P.'s unusual deficit supports the hypothesis that semantic knowledge is organized in the brain on the basis of object properties, which can cut across the living-nonliving categorical distinction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pure alexia and word-meaning deafness in a patient with multiple sclerosis

OBJECTIVE: To describe pure alexia and auditory comprehension problems in a young woman with multiple sclerosis (MS). PATIENT: A 33-year-old woman with MS who complained of difficulties in reading and comprehending spoken language was referred for a neuropsychological examination. Reading difficulties were confirmed and most of the reading errors were additions, omissions, and substitutions of single letters. While the patient reported that the letters seemed to disappear before her eyes, no general problems with visual attention, visual discrimination, or scanning were detected. No difficulties with spelling were reported. The auditory comprehension deficit is interpreted as a form of a semantic access disorder and is not due to generalized slowing in information processing or conceptual disintegration. CONCLUSIONS: Pure alexia is unusual in MS and to our knowledge only 1 other case has been reported (in Japanese). Memory impairments and slowed information processing are probably the most frequent cognitive sequelae of the disease and, consequently, the literature is biased toward the study of those cognitive domains. However, given the wide distribution of sclerotic plaques in MS, it could be argued that we should expect some variability of cognitive changes in MS. Striking deficits as seen in this patient should make us more sensitive to this possibility.     

Analyzing the factors underlying the structure and computation of the meaning of chipmunk, cherry, chisel, cheese, and cello (and many other such concrete nouns).

Seven trends regarding the categories that tend to be impaired/preserved in category-specific semantic deficits were identified. The authors hypothesized that these trends arise despite the multiple sources of variation in patient testing because numerous factors that structure semantic memory probabilistically converge to make some categories of knowledge more susceptible to damage than others. Analysis of semantic feature norms and corpus data for 541 concepts revealed that differences in the distribution of knowledge types across categories are sufficient to explain 6 of the trends and are necessary to explain loss of knowledge about nonliving things. Feature informativeness, concept confusability, visual complexity, familiarity, and name frequency contributed to this patterning and provide insight into why knowledge about living things is most often impaired. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual complexity in letter-by-letter reading: "pure" alexia is not pure

Standard accounts of pure alexia have favoured the view that this acquired disorder of reading arises from damage to a left posterior occipital cortex mechanism dedicated to the processing of alphanumeric symbols. We challenge these accounts in two experiments and demonstrate that patients with this reading deficit are also impaired at object identification. In the first experiment, we show that a single subject, EL, who shows all the hallmark features of pure alexia, is impaired at picture identification across a large set of stimuli. As the visual complexity of pictures increases, so EL's reaction time to identify the stimuli increases disproportionately relative to the control subjects. In the second experiment, we confirm these findings with a larger group of five pure alexic patients using a selected subset of high- and low-visual complexity pictures. These findings suggest that the deficit giving rise to pure alexia is not restricted to orthographic symbols per se but, rather, is a consequence of damage to a more general-purpose visual processing mechanism.     

Intact visual imagery and impaired visual perception in a patient with visual agnosia.

Although it is now well accepted that visual mental imagery and visual perception share common underlying mechanisms, there are several reports in which they are dissociated. Evidence for the separability of these processes is provided by a 33-yr-old male patient who has a profound visual object recognition deficit attributable to an impairment in grouping or segmenting visual images. Despite this perceptual deficit, the patient was able to draw objects in considerable detail from memory, and his knowledge of the visual appearance of objects was preserved on a variety of mental imagery tasks. Together with previous cases, these findings confirm the double dissociation between object recognition and perception. Interestingly, the patient could also recognize newly constructed objects in his internal imagery. To accommodate these results, the authors propose a model in which imagery and perception are strongly associated but are also functionally specialized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual hallucinations in schizophrenia: Confusion between imagination and perception.

Objective: An association between hallucinations and reality-monitoring deficit has been repeatedly observed in patients with schizophrenia. Most data concern auditory/verbal hallucinations. The aim of this study was to investigate the association between visual hallucinations and a specific type of reality-monitoring deficit, namely confusion between imagined and perceived pictures. Method: Forty-one patients with schizophrenia and 43 healthy control participants completed a reality-monitoring task. Thirty-two items were presented either as written words or as pictures. After the presentation phase, participants had to recognize the target words and pictures among distractors, and then remember their mode of presentation. Results: All groups of participants recognized the pictures better than the words, except the patients with visual hallucinations, who presented the opposite pattern. The participants with visual hallucinations made more misattributions to pictures than did the others, and higher ratings of visual hallucinations were correlated with increased tendency to remember words as pictures. No association with auditory hallucinations was revealed. Conclusions: Our data suggest that visual hallucinations are associated with confusion between visual mental images and perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What is it like to be a patient with apperceptive agnosia?

Neuropsychological deficits have been widely used to elucidate normal cognitive functioning. Can patients with such deficits also be used to understand conscious visual experience? In this paper, we ask what it would be like to be a patient with apperceptive agnosia (a deficit in object recognition). Philosophical analyses of such questions have suggested that subjectively experiencing what another person experiences would be impossible. Although such roadblocks into the conscious experience of others exist, the experimental study of both patients and neurologically normal subjects can be used to understand visual processing mechanisms. In order to understand the visual processes damaged in apperceptive agnosia, we first review this syndrome and present a case study of one such patient, patient J.W. We then review several theoretical accounts of apperceptive agnosia, and we conclude that studies of the patients themselves may not allow us to discriminate between the various explanations of the syndrome. To test these accounts, we have simulated apperceptive agnosia in neurologically normal subjects. The implications of our results for understanding both apperceptive agnosia and normal visual processing are discussed.     

Detecting and remembering simultaneous pictures in a rapid serial visual presentation.

Viewers can easily spot a target picture in a rapid serial visual presentation (RSVP), but can they do so if more than 1 picture is presented simultaneously? Up to 4 pictures were presented on each RSVP frame, for 240 to 720 ms/frame. In a detection task, the target was verbally specified before each trial (e.g., man with violin); in a memory task, recognition was tested after each sequence. Target detection was much better than recognition memory, but in both tasks the more pictures on the frame, the lower the performance. When the presentation duration was set at 160 ms with a variable interframe interval such that the total times were the same as in the initial experiments, the results were similar. The results suggest that visual processing occurs in 2 stages: fast, global processing of all pictures in Stage 1 (usually sufficient for detection) and slower, serial processing in Stage 2 (usually necessary for subsequent memory). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Activating representations in permanent memory: different benefits for pictures and words

Previous research has suggested that pictures have privileged access to semantic memory (W. R. Glaser, 1992), but J. Theios and P. C. Amrhein (1989b) argued that prior studies inappropriately used large pictures and small words. In Experiment 1, participants categorized pictures reliably faster than words, even when both types of items were of optimal perceptual size. In Experiment 2, a poststimulus flashmask and judgments about internal features did not eliminate picture superiority, indicating that it was not due to differences in early visual processing or analysis of visible features. In Experiment 3, when participants made judgments about whether items were related, latencies were reliably faster for categorically related pictures than for words, but there was no picture advantage for noncategorically associated items. Results indicate that pictures have privileged access to semantic memory for categories, but that neither pictures nor words seem to have privileged access to noncategorical associations.     

Neural correlates of the episodic encoding of pictures and words

A striking characteristic of human memory is that pictures are remembered better than words. We examined the neural correlates of memory for pictures and words in the context of episodic memory encoding to determine material-specific differences in brain activity patterns. To do this, we used positron emission tomography to map the brain regions active during encoding of words and pictures of objects. Encoding was carried out by using three different strategies to explore possible interactions between material specificity and types of processing. Encoding of pictures resulted in greater activity of bilateral visual and medial temporal cortices, compared with encoding words, whereas encoding of words was associated with increased activity in prefrontal and temporoparietal regions related to language function. Each encoding strategy was characterized by a distinctive activity pattern, but these patterns were largely the same for pictures and words. Thus, superior overall memory for pictures may be mediated by more effective and automatic engagement of areas important for visual memory, including medial temporal cortex, whereas the mechanisms underlying specific encoding strategies appear to operate similarly on pictures and words.     

Retrieval monitoring and anosognosia in Alzheimer's disease.

This study explored the relationship between episodic memory and anosognosia (a lack of deficit awareness) among patients with mild Alzheimer's disease (AD). Participants studied words and pictures for subsequent memory tests. Healthy older adults made fewer false recognition errors when trying to remember pictures compared with words, suggesting that the perceptual distinctiveness of picture memories enhanced retrieval monitoring (the distinctiveness heuristic). In contrast, although participants with AD could discriminate between studied and nonstudied items, they had difficulty recollecting the specific presentation formats (words or pictures), and they had limited use of the distinctiveness heuristic. Critically, the demands of the memory test modulated the relationship between memory accuracy and anosognosia. Greater anosognosia was associated with impaired memory accuracy when participants with AD tried to remember words but not when they tried to remember pictures. These data further delineate the retrieval monitoring difficulties among individuals with AD and suggest that anosognosia measures are most likely to correlate with memory tests that require the effortful retrieval of nondistinctive information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Category-specific naming impairments? Yes

Recently, Stewart, Parkin, and Hunkin (1992) have questioned previously reported cases of selective damage in processing items from categories of animate objects, arguing that there has been a lack of adequate control for visual familiarity, visual complexity, and name frequency of the stimuli employed. When re-testing Michelangelo (see Sartori & Job, 1988), one of the patients cited by Stewart et al. (1992), with a set of materials matched on all three factors, the asymmetry in naming animal and artefact items still remains. An analogous pattern is obtained when--in addition to such factors--the visual similarity within the sub-sets of animals and artefacts is taken into account. These results constitute empirical evidence for category-specific impairments and cannot be interpreted as being due to isolated or conjoint effects of visual familiarity, visual complexity, or name frequency.     

Rapid picture presentation and affective engagement.

Emotional reactions were assessed to pictorial stimuli presented in a continuous stream at rapid speeds that compromise conceptual memory and the processing of specific picture content. Blocks of unpleasant, neutral, or pleasant pictures were presented at the rate of either three pictures per second or seven pictures per second. Even with rapid presentation rates, startle reflexes, corrugator muscle activity, and skin conductance responses were heightened when viewing unpleasant pictures. These effects were stronger later in the aversive block, suggesting that cumulative exposure increasingly activates the defense system. The findings suggest that, despite conceptual masking inherent in rapid serial visual presentation, affective pictures prompt measurable emotional engagement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pictures, images, and recollective experience.

Five experiments investigated the influence of picture processing on recollective experience in recognition memory. 16 undergraduate Ss studied items that differed in visual or imaginal detail, such as pictures vs words and high-imageability vs low-imageability words, and performed orienting tasks that directed processing either toward a stimulus as a word or toward a stimulus as a picture or image. Standard effects of imageability (e.g., the picture superiority effect and memory advantages following imagery) were obtained only in recognition judgments that featured recollective experience and were eliminated or reversed when recognition was not accompanied by recollective experience. It is proposed that conscious recollective experience in recognition memory is cued by attributes of retrieved memories such as sensory-perceptual attributes and records of cognitive operations performed at encoding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociating the roles of dorsal and ventral CA1 for the temporal processing of spatial locations, visual objects, and odors.

The differential contributions of the dorsal and ventral hippocampus for learning and memory have long been of interest. The present experiments were designed to evaluate the contributions of dorsal CA1 and ventral CA1 for temporal processing. Animals were run on three temporal ordering paradigms: one with visual objects, one with olfactory stimuli, and one with spatial locations. Animals with lesions to dorsal CA1 showed deficits for the temporal ordering of visual objects relative to control animals, and deficits for the temporal ordering of spatial locations relative to control and ventral CA1 lesioned animals. Animals with lesions to ventral CA1 showed deficits for the temporal ordering of olfactory information relative to control and dorsal CA1 lesioned animals, and a mild deficit for the temporal ordering of visual objects relative to control animals, but not as severe as those shown by the dorsal CA1 lesioned animals. These data suggest that dorsal CA1 and ventral CA1 contribute to temporal ordering processes, and that dorsal CA1 and ventral CA1 are dissociable for temporal ordering based upon the nature of the information that is processed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual priming of proper names in young and older normal adults and a patient with prosopanomia.

The purpose of this study was to determine if normal participants and a patient with prosopanomia can be perceptually primed for proper names. To this end, 2 experiments were conducted. In Experiment 1, normative data were collected on 4 proper-name priming tasks. The variables of levels of processing at encoding and age were manipulated. Robust priming results were obtained that were not influenced by either of these variables. The results of Experiment 2 indicated that prosopanomic patient, N.G., demonstrated normal repetition priming, despite her marked impairment in deliberate retrieval of person and city names. These results are interpreted in terms of a dissociation between explicit and implicit memory for proper names and suggest that the deficit in prosopanomia only involves deliberate access to the name; access to presemantic representations of the visual word form remains intact. (PsycINFO Database Record (c) 2010 APA, all rights reserved)