Cortisol inversely related to prefrontal gamma coherence in healthy human subjects.
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Adolescent↗
Biomedical subjects
E H De Haan
Publications and source records attributed to E H De Haan.
Nonlanguage cognitive deficits and hallucinations in schizophrenia.
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Auditory Perceptual Disorders↗
Perception, mental imagery and reality discrimination in hallucinating and non-hallucinating schizophrenic patients.
OBJECTIVES: In this study the hypothesis was tested that hallucinations result from confusing external and internal stimulus sources, i.e., perception and imagery, respectively. DESIGN AND METHODS: Thirteen hallucinating and 19 non-hallucinating schizophrenic patients, as well as 14 control participants performed multiple tests of perception, vividness of mental imagery and the ability to discriminate between them (reality discrimination). These functions were tested in both the auditory and the visual modalities. RESULTS: There were no group differences on perceptual acuity. The results on one imagery task indicated that for the hallucinating patients, the relative, but not the absolute, level of vividness of mental images might be higher in the auditory modality, which was the modality in which 12 of the patients also experienced hallucinations, than in the visual modality. Finally, there was a positive relationship between severity of (auditory) hallucinations and reality discrimination problems. CONCLUSIONS: Hallucinations may result from increased vividness of mental imagery, and their severity increases with larger impairments in reality discrimination. It is recommended that research into, and cognitive behavioural therapy for, hallucinations should also focus on their sensory qualities.
Adult↗
A familial factor in the development of face recognition deficits.
The face is probably the single most important visual object. It is the main cue for identifying familiar people and crucial in nonverbal communication. Face recognition can be demonstrated in newborn babies, suggesting that face recognition is to some degree 'hard-wired' in the brain. Also, neurological disease can selectively disrupt the ability to recognize faces. Apart from acquired face recognition deficits, developmental cases have been reported. This study presents a family in which the father and two of his daughters are very poor at recognizing faces, demonstrating for the first time a familial factor in developmental face recognition deficit.
Adult↗
Mood improvement from transcranial magnetic stimulation.
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Adult↗
Insulin-like growth factor-I and cognitive function in healthy older men.
The GH/insulin-like growth factor-I (GH/IGF-I) axis is known to be involved in aging of physiological functions. Recent studies indicate that the GH/IGF-I axis may be associated with cognitive functioning. The aim of the present study was to determine whether the age-related decline in circulating levels of IGF-I, as an index of anabolic status, is associated with cognitive functions that are known to decline with aging, but not with cognitive functions not sensitive to aging. Twenty five healthy older men with well-preserved functional ability participated in the study. We also administered neuropsychological tests of general knowledge, vocabulary, basic visual perception, reading ability, visuoconstructive ability, perceptual-motor speed, mental tracking, and verbal long-term memory. Performance on the last four tests decline with aging, whereas the first four of these tests have been shown not to be sensitive to cognitive aging. Mean age of the subjects was 69.1 +/- 3.4 (SD) yr (range 65-76 yr), their mean body mass index was 27.0 +/- 2.4 kg/m2, and their mean IGF-I level was 122 ng/mL (range: 50-220). We found IGF-I levels to be significantly associated with the performances (controlled for education) on the Digit Symbol Substitution test (r = 0.52, P = 0.009) and the Concept Shifting Task (r = -0.55, P = 0.005), which measure perceptual-motor and mental processing speed. Subjects with higher IGF-I levels performed better on these tests, performance on which is known to decline with aging. In conclusion, the results of this study support the hypothesis that circulating IGF-I may play a role in the age-related reduction of certain cognitive functions, specifically speed of information processing.
Aged↗
Sex differences in object location memory.
The ability to remember where objects were is thought to require multiple separate processes. One has to encode the precise positions occupied, assign the various objects to the correct (relative) locations, and achieve an integration of both types of spatial information. This study examined whether sex differences exist for these selective components of object location memory. Twenty males and 20 females participated in the following task. On a PC screen, they were shown a square with 10 different objects for 30 s. Subsequently, the objects disappeared from the screen, reappeared in a row above the square, and subjects were asked to relocate them in three different conditions. In the object-to-position-assignment condition, the original positions were premarked in the square, so subjects needed only to assign the correct object to the correct position. In the positions-only condition, all objects assumed the same identity. Therefore, subjects had only to reproduce the precise positions. Finally, in the combined condition, subjects were required to replace all the different objects in the square without any of object positions premarked. The absolute displacements between an object's original and its relocated position reflect the integration mechanism. Females did as well as males in the object-to-position-assignment condition and on the absolute displacements in the combined condition, but they were less efficient than males in positional reconstruction per se. Thus, it seems that the male advantage in spatial memory is not a general effect but applies only to certain specific processing components. Moreover, the employment of a dual task during encoding, concurrent articulatory suppression, yielded no significant interactions with sex. This suggests that females' weaker positional encoding does not derive from the use of an inefficient verbal strategy.
Adult↗
Decreased capacity for mental effort after single supratentorial lacunar infarct may affect performance in everyday life.
OBJECTIVES: The long term outcome after a single symptomatic lacunar infarct may be less favourable than is generally assumed. Patients often present with complaints such as fatigue or "being different from before the stroke", for which there are no obvious physical explanations. Although cognitive functioning is considered normal in most patients with lacunar infarction in the internal capsule or corona radiata, a study was carried out to determine if subclinical changes in mental or emotional function can explain these vague complaints characteristic for their disablement. METHODS: Sixteen patients, each with a single symptomatic supratentorial lacunar infarct, and 16 matched healthy controls were examined with an extensive neuropsychological screening battery and a standardised questionnaire aimed at emotional problems. The mean number of correct responses was calculated for each subject and averaged within each group. RESULTS: Although, on the whole, there were no differences in performance, patients' results on the following tasks in different modalities showed evidence for decreased performance under relatively more demanding conditions: line orientation task (mean difference (MD) 261 ms; 95% confidence interval (95%CI) 94 to 428), Rey-Osterrieth delayed recall (MD-3.8, 95% CI -7.5 to 0.0), visual elevator subtest of the everyday attention task (EAT) (MD -0.7, 95% CI -1.5 to 0.1), lottery subtest of the EAT (MD -0.6, 95% CI -1.3 to 0.1) and WAIS similarities (MD -3.2 95% CI -6.3 to 0.1). Patients also more often had emotional disturbances than controls. CONCLUSION: Both subtle cognitive impairments and emotional disturbances may play a part in the decreased competence in everyday life of patients with a supratentorial lacunar infarct.
Activities of Daily Living↗
What was where? Memory for object locations.
Three experiments are reported on short-term memory for object location. Stimulus displays containing different numbers and types of objects were presented for 30 seconds, after which subjects were required to relocate the various objects within the display, merely to reconstruct positions, or to assign objects correctly to an equal number of premarked positions. In all experiments half the trials were performed with concurrent articulatory suppression. The results support the hypothesis that two processes can be distinguished: one that underlies the construction of a positional map and one that assigns objects to positions. These processes are differentially affected by object numbers and articulatory suppression. This hypothesis is discussed in terms of Baddeley's (1986) working memory model and Kosslyn's (1987) distinction between "categorical" and "coordinate" spatial relations.
Adult↗
Random generation deficit in alcoholic Korsakoff patients.
Korsakoff's syndrome often affects "executive" functions [Baddeley, A. Human Memory, Theory and Practice, 1990], which in anatomical terms are associated with the frontal lobes. However, in a previous study, Wiegersma, S. and de Jong, E. [J. clin. exp. Neuropsychol. 13, 847-853, 1991] failed to observe a diminished performance on the random generation task, although this task is thought to be sensitive to "executive" deficits. In the present study, we sought to replicate and clarify these earlier findings of Wiegersma and de Jong with a group of Korsakoff patients in whom frontal lobe dysfunction was indicated by a reduced performance on fluency tasks. Patients and controls were presented with three tasks. Digit span was used as an index of short-term memory capacity; memory search and comparison processes were measured with the missing item scan; and the randomisation task was used to assess the ability to produce non-routine, random sequences. The results showed that the performance of Korsakoff patients declined on the randomisation task while short-term retention and scanning were intact. Analysis of the responses indicated that the Korsakoff patients are able to suppress the dominant response, but have problems in generating and carrying out alternative strategies in novel problem situations.
Acoustic Stimulation↗
Ettlinger revisited: the relation between agnosia and sensory impairment.
The concept of agnosia as a higher order functional impairment, which can occur in the absence of low level visual perceptual deficits, continues to provoke debate. This controversy is complicated by the fact that, on close examination, agnosic patients do tend to have some perceptual difficulties. Thus the issue centres around the question as to whether these deficits play a causal part in the aetiology of agnosia or whether they are functionally independent, with both impairments resulting from the substantial cerebral lesions involved in agnosia. In 1956, Ettlinger published a study in which he compared the performance of patients with visual recognition deficits and patients with posterior brain lesions whose recognition abilities were intact. He argued that visual perceptual problems could not explain the recognition deficit in agnosia as he saw far worse perceptual impairments in patients who did not experience any problems in visual recognition. Although the logic of Ettlinger's argument is not disputed, some criticisms have arisen concerning the study, such as the fact that his experimental group did not include a truly object agnosic patient. In addition, Ettlinger's visual-sensory assessment can no longer be considered comprehensive in the light of present day knowledge of the cerebral visual apparatus. This study therefore investigated three (prosop)agnosic patients and five patients with unilateral brain lesions without recognition deficits on an extensive battery of visual sensory tests. The results support Ettlinger's original claim that (in some cases) agnosia cannot be explained as resulting from lower level visual impairments.
Adult↗
Behavioural and physiological evidence for covert face recognition in a prosopagnosic patient.
In a previous report, Bauer (1984) described the patient LF, who was unable to recognise familiar faces. Despite the inability to verbally identify familiar faces, psychophysiological examination revealed preserved covert processing of facial identity. Subsequent studies have demonstrated covert face recognition using behavioural tasks. Investigations of the patient PH showed normal face familiarity effects on matching, interference, priming, and learning tasks, while overt recognition was completely absent (De Haan, Young and Newcombe, 1987b). The use of different methodologies has led to different theoretical conceptualisation of the "covert recognition" phenomenon. Until now, no individual patient has been exposed to both methodologies. In this study we evaluated LF, who shows psychophysiological evidence of covert recognition, using behavioural tasks previously used with PH. The results reveal clear behavioural evidence of preserved face recognition without awareness. These findings suggest that both methodologies tap similar phenomena, and have important implications for theoretical models of covert face recognition. A conceptual model designed to integrate psychophysiological and behavioural evidence of covert face recognition is proposed.
Agnosia↗
Neuropsychological impairment of face recognition units.
Despite the absence of "conscious", overt identification, some patients with face recognition impairments continue covertly to process information regarding face familiarity. The fact that by no means all patients show these covert effects has led to the suggestion that indirect recognition tasks may help in identifying different types of face recognition impairment. The present report describes a number of experiments with the patient NR, who, after a closed head injury, has been severely impaired at recognizing familiar faces. Investigations mostly failed to show overt or covert face recognition, but NR performed at an above-chance level in selecting the familiar face on a task requiring a forced-choice between a familiar and an unfamiliar face. This discrepancy between a degree of rudimentary overt recognition and absence of covert effects on most indirect tests was addressed using a cross-domain identity priming paradigm. This examined separately the possibility of preserved recognition for faces that NR consistently chose correctly in a forced-choice familiarity decision and those on which he performed at chance level. Priming effects were apparent only for the faces that were consistently chosen as "familiar" in forced-choice. We suggest that NR's stored representations of familiar faces are degraded, so that face recognition is possible only via a limited set of relatively preserved representations able to support a rudimentary form of overt recognition and to facilitate performance in matching and priming tasks.
Adult↗
Neuropsychology of vision.
A selection of the literature on vision published in the last 2 years from various neuroscience disciplines is reviewed. It is organized around the notion of independent processing mechanisms for sensory cues such as wavelength, intensity and orientation; these are subsequently integrated for the perception of colour, brightness and contours, for example, which then feed into higher order systems for visual recognition (words and objects) and visuospatial cognition. A strict hierarchical system is, however, not plausible. Apart from the physiological evidence against such a concept, the widespread observations of 'knowledge without awareness' suggest direct links between different levels, which by-pass conscious experience.
Attention↗
A fifteen year follow-up of a case of developmental prosopagnosia.
The term developmental prosopagnosia refers to an impairment in the recognition of familiar faces which has been present from birth in the absence of neurological disease or birth complications. The first reported study was by McConachie (1976, Cortex, 12: 76-82) and we report here a fifteen year follow-up on this case (AB). Recently developed theoretical models postulating separate processes involved in face perception and recognition were used to guide the exploration of her functional deficit. Our investigations with AB showed that basic visuo-sensory functions (acuity, contrast sensitivity, colour, etc.) were largely intact. General face perception (e.g. distinguishing between a face and a "nonface") was relatively well preserved. Recognition of familiar faces was severely impaired and she also showed problems with other face processing tasks (e.g. analysis of facial expression) and in object recognition. In object recognition she made errors based on visual similarity, and she had problems identifying exemplars from categories with many visually similar items. In addition, she was very poor at identifying objects or silhouettes from an unusual viewpoint. We conclude that AB has always been poor at constructing an effective internal representation sufficient to permit recognition of items which are visually difficult to discriminate. Therefore, she may not have been able to acquire useable stored representations either, because this deficit has been present since birth. This functional account was supported by subsequent studies which demonstrated a complete absence of covert face recognition.
Agnosia↗
Covert and overt recognition in prosopagnosia.
Prosopagnosic patients suffer an inability to recognize familiar people by visual inspection of their faces. Despite the absence of overt recognition, though, some prosopagnosic patients continue to process the identities of familiar faces covertly. A longstanding controversy concerns whether the recognition deficit in prosopagnosia is specific for faces, or also affects other types of visual stimuli. We investigated whether the patient P.H., who has severe problems with within-class recognition of many types of visual stimuli, would show covert recognition for all stimuli which he cannot recognize overtly. Such a finding would be consistent with the idea that face recognition and recognition of other visually similar stimuli are performed by the same underlying functional mechanisms. We assessed this possibility with a forced-choice decision between correct and incorrect alternative names for familiar faces, cars and flowers, and with comparisons of P.H.'s ability to learn true versus untrue names to familiar faces, cars and flowers. Results indicated that P.H. does show covert recognition of cars and flowers, as well as faces. In addition, the covert effects observed in the forced-choice name decision and learning tasks used here were shown to have a potential common basis. Finally, the possibility of using covert knowledge as a basis for rehabilitation was explored. As was observed by Sergent and Poncet (1990) in their patient, P.H. could achieve some overt face recognition under very specific circumstances.
Adult↗
Prosopagnosia and object agnosia without covert recognition.
Investigations of the visual recognition abilities of the patient M.S. are reported. M.S. is unable to achieve overt recognition of any familiar faces, and many everyday objects. In Task 1 he showed semantic priming from name primes but not from face primes in a name recognition task. In Task 2 he showed no advantage in learning true (face + correct name) rather than untrue (face + someone else's name) pairings of faces and names. In Task 3 semantic priming of lexical decision was only found for object picture primes that M.S. was able to recognize overtly. In Task 4 faster matching of photographs of familiar than unfamiliar objects was only found for objects that M.S. was able to recognize overtly. These findings demonstrate an absence of covert recognition effects for M.S., consistent with the view that his impairment is primarily "perceptual" in nature.
Adult↗
Cross-domain semantic priming in normal subjects and a prosopagnosic patient.
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Adult↗