Visuoperceptual-spatial ability and visual memory in vascular dementia and dementia of the Alzheimer type.

This study investigated the relationship between visuoperceptual ability and visual memory in dementia. Twenty individuals with probable dementia of the Alzheimer type, 24 individuals with probable vascular dementia, and 20 healthy, elderly adults underwent neuropsychological evaluation. Hierarchical multiple regression analyses suggested that perceptual organization skills contributed to a significant amount of the variance in novel, but not famous, face recognition. This finding was most robust in the clinical groups. Causality cannot be attributed from this regression model. Results suggest, however, that visual processing deficits are more strongly related to the memory process at the time of encoding rather than during recognition of remote information.

Discriminative stimulus effects of the optical isomers of 3,4-methylenedioxyamphetamine (MDA).

The isomers of 3,4-methylenedioxyamphetamine (MDA) functioned as discriminative stimuli in rats trained to discriminate either (-) MDA (1.25mg/kg) or (+) MDA (1.25mg/kg) from saline. Dose- and time-response curves indicated that drug lever selection occurred at doses of at least 1.00mg/kg of (-) MDA and 0.75mg/kg of (+) MDA and that drug-appropriate responding for both isomers was maintained for at least 90min. Cross-substitution was observed between the MDA isomers; both (+) and (-) 3,4-methylenedioxymethamphetamine (MDMA) also substituted completely for (+) and (-) MDA. The hallucinogens (+)-lysergic acid diethylamide (LSD) and (+/-)-2,5-dimethoxy-4-methylamphetamine (DOM), substituted for (-) MDA; neither mescaline nor (+) amphetamine or cocaine had (-) MDA-like effects. LSD also substituted for (+) MDA; DOM, mescaline, (+) amphetamine and cocaine failed to have (+) MDA-like effects. The (-) but not the (+) MDA cue was blocked by the 5-HT(2) antagonist pirenpirone; the dopamine (DA) antagonists SCH-23390 and (-) sulpiride had no effect on either the (-) or (+) MDA cues. When animals were trained to discriminate LSD (0.16mg/kg) or (+) amphetamine (1.0mg/kg) from saline, neither (-) MDA nor (+) MDA substituted completely. These results indicate that: (1) the stimulus effects of the isomers of MDA and MDMA are similar; (2) (-) MDA may be more hallucinogenic (or more accurately, LSD- or DOM-like) than (+) MDA; (3) neither (+) nor (-) MDA has potent amphetamine-like effects; and (4) the effects of (-) MDA may be more serotonergic than those of (+) MDA.

Concurrent validity of the MAE visual naming test.

Deficient confrontation naming has been observed in a number of neurological illnesses, as well as in aphasia and normal aging. The Visual Naming Test (VNT) of the Multilingual Aphasia Examination (MAE) is a standardized measure of confrontation naming. One hundred patients, consecutively referred for neuropsychological evaluation, were administered the VNT, Boston Naming Test (BNT), and WAIS-R. Concurrent validity of the two confrontation naming measures was demonstrated by their high intertest agreement. Performance on the VNT was found to be related to a unique ability separate from general intellectual functioning. Suggestions regarding the clinical use of the VNT are discussed.

Diagnostic efficiency and material specificity of the Warrington Recognition Memory Test: a collaborative multisite investigation.

Two studies examined the Warrington Recognition Memory Test (RMT) discrepancy index (Words-Faces) in a large sample of patients heterogeneous with respect to age, education, gender, and neurological diagnosis. In Study 1 (N = 504) we used cutoffs from the Words-Faces discrepancy scores derived from Warrington's original validation sample to attempt to accurately classify patients with left, right, or diffuse brain damage. Sensitivity for left hemisphere patients (Faces > Words) was 10% with a specificity of 88%, whereas sensitivity for right hemisphere patients (Words > Faces) was 48% with a specificity of 86%. For patients with diffuse brain damage (Words = Faces) sensitivity was 69% and specificity was 38%. In Study 2 (N = 263), we examined the relationship between the Words-Faces discrepancy score and Wechsler Memory Scale-Revised (WMS-R; Wechsler, 1981) Logical Memory and Visual Reproduction subtests. Contrary to predictions, patients with Words > Faces performed better on both WMS-R subtests; the Faces > Words discrepancy was not related to Visual Reproduction performance. Potential reasons for these negative findings are discussed, as well as cautions for future RMT discrepancy index use.

Traumatic brain injury rehabilitation: is it worth the cost?

Traumatic brain injury (TB1) rehabilitation is a costly process. In past years it came under increasing scrutiny resulting from lack of hard data supporting its efficacy, as well as outright fraud and abuses in the head-injury rehabilitation industry. Nonetheless, appropriate TBI rehabilitation holds promise for improving the functional outcomes of brain injury survivors and can also reduce future expenditures. This article reviews the empirical literature regarding TBI rehabilitation outcome, with particular emphasis on studies that have examined the cost efficiency of rehabilitation. Specific implications and recommendations are offered for neuropsychologists who practice within the context of TBI rehabilitation.

Clinical utility of a recognition paradigm of the Visual Form Discrimination Test.

The utility of the Visual Form Discrimination Test as a motor free test of visual discrimination and recognition memory was first evaluated in samples of young and elderly community dwelling adults. Weighted score performance on the discrimination test was approximately two points higher than that of the recognition test for both age groups. The older group made more peripheral errors on both versions of the test and fewer correct responses on the recognition test than the younger group. In Study 2, the Visual Form tasks were administered to patient groups with left or right hemisphere stroke. Both patient groups were lower on both the discrimination and recognition versions of the Visual Form Test relative to the controls in Study 1. When evaluating the visual field in which major rotations and major distortions occurred, the expected contralateral neglect was observed for the stroke groups. The recognition version of the Visual Form Test appears to be sensitive to subtle hemi-spatial neglect. The results from these studies support the utility of these motor-free visual processing tasks.

Verbal learning and memory impairment in adult civilians following penetrating missile wounds.

Verbal memory and learning patterns, as measured by the California Verbal Learning Test (CVLT), following penetrating head injury (PHI) from gunshot wound were studied in 10 acutely injured patients (mean age 25.3 years) at a mean of 2.1 months post-injury. Primary impairment was found on measures of free recall of new verbal information which appeared to be related to deficits in organisational and retrieval functions: (1) the group's learning characteristics were marked by disorganization and an underutilization of active learning strategies; (2) rate of acquisition also appeared to be mildly decreased; (3) nevertheless, the PHI group did not show severe disruption in all aspects of learning and memory. In fact, the group showed a relatively intact capacity to store new information in memory.

Functional neuroimaging and quantitative electroencephalography in adult traumatic head injury: clinical applications and interpretive cautions.

Functional neuroimaging and quantitative electroencephalographic procedures are being used increasingly in brain injury research and clinical care. These procedures are also seeing increased use in the context of forensic evaluations, particularly in cases of mild head trauma. This article provides an overview of the use of procedures such as positron emission tomography, single photon emission computed tomography, and quantitative electroencephalogram in adults. Also discussed are the clinical limitations of each procedure within the context of myriad interpretive confounds that can interfere with accurate differential diagnosis of mild head trauma.

Verbal learning patterns in moderate and severe traumatic brain injury.

Previous studies that have examined performances on the California Verbal Learning Test (CVLT) among individuals with traumatic brain injury (TBI) have found differing levels of performance. Differential patterns of performance, however, have only been inferred. The present investigation sought to determine empirically if differential patterns of performance could be discerned in a TBI sample of 65 subjects with CVLT variables. The CVLT variables were selected based on the instrument's factor structure. Cluster analysis yielded four distinct subtypes of brain-injured individuals. The Active subtype demonstrated impaired unassisted retrieval, but used active encoding strategies and showed relatively intact ability to store novel information. The Disorganized subtype demonstrated an inconsistent, haphazard learning style along with deficits in encoding. The Passive subtype was marked by an overreliance on a serial clustering strategy as well as impaired encoding and/or consolidation. The Deficient subtype was the most impaired of all groups, exhibiting a slowed rate of acquisition, passive learning style, and significant impairment in encoding. Implications for rehabilitation are discussed.

Differential visuospatial dysfunction following striatal, frontal white matter, or posterior thalamic infarction.

The present study investigated visuospatial functioning in 35 right-hand dominant patients with striatal, frontal white matter, or posterior thalamic infarction, in the right cerebral hemisphere. On tasks of visual detection and discrimination, the groups performed within normal limits and comparable to one another. On tasks of visual synthesis and spatial analysis, each group was significantly impaired, with greatest impairment following infarction of deep grey structures. Correlational analyses indicated that in the striatal and frontal white matter groups, visual synthesis and spatial analysis task performance were strongly correlated with performance on neuropsychological tests of executive control. This relationship was not observed in the posterior thalamic group. The results support the hypothesis of differential patterns of visuospatial performance depending on the anatomical locus of subcortical lesions. The findings are explained in terms of differing subcortical circuitry and suggest that multiple substrates mediate the sequelae of subcortical lesions.

Detection of incomplete effort on the Wechsler Adult Intelligence Scale-Revised: a cross-validation.

This study determined whether the Vocabulary-Digit Span difference score and discriminant function based on subtests of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) developed by Mittenberg et al. (1995) could differentiate patients with moderate and severe traumatic brain injuries (n = 50) from persons with financially compensable mild head injuries who were giving incomplete effort (n = 50). Employing modified cutoff scores, the discriminant function and Vocabulary-Digit Span difference score accurately classified 90% and 79% of the cases, respectively. Persons with traumatic brain injuries may produce WAIS-R subtest patterns that can be differentiated from individuals showing incomplete effort. These WAIS-R algorithms appear useful in making that distinction.

Functionally activated brain imaging (O-15 PET and fMRI) in the study of learning and memory after traumatic brain injury.

Advances in functional imaging technology and cognitive neuropsychology have resulted in paradigms in which participants can perform cognitive tasks during functional image acquisition. We will discuss the application of two approaches (oxygen-15 positron emission tomography and functional magnetic resonance imaging) that have recently been used to examine components of learning and memory following traumatic brain injury (TBI). Activated functional brain imaging findings that we will discuss may suggest possible functional reallocation and reorganization of brain substrates involved in verbal learning and memory following brain injury. The findings also are clearly in line with other research that indicates a prominent role for the frontal lobes in learning and memory functioning, and support the concept of distributed neural networks for memory-related functions, cognitive load, and the potential for examining brain re-organization after injury.

Fractioning the Hooper: a multiple-choice response format.

The Hooper Visual Organization Test (HVOT) provides an excellent illustration of the multifactorial nature of most neuropsychological tests. Although the HVOT clearly requires certain visual perceptual skills, the test also demands that the subject produce an overt verbal response - i.e., the name of the object that has been cut up and rearranged. Thus, individuals with disorders of confrontation naming may obtain low scores on the HVOT by virtue of their anomia, even if the primary perceptual skills that the HVOT purports to assess are intact. The present study was designed to minimize the demands of object naming on HVOT performance, by using a multiple choice format of the HVOT. Fourteen individuals with lateralized injury resulting from either cerebral vascular accident or cerebral contusion were administered the Boston Naming Test (BNT) and the standard version of the HVOT. Approximately 24 hours later, subjects were administered the Multiple-Choice Hooper Visual Organization Test (MC-HVOT). The MC-HVOT consisted of the 30 original HVOT stimuli presented with four response choices, including the correct response and three foils. A paired sample t test revealed that anomic subjects achieved a significantly greater number of correct responses on the MC-HVOT then under the standard HVOT administration. Subjects with both right and left hemisphere involvement benefited from diminished naming demands. Overall HVOT performance significantly improved when the object naming demand was reduced, resulting in a clearer assessment of visual integration skills. These findings may have significant implications for both interpretation of impairment and formulation of treatment recommendations.

Learning impairment is associated with recall ability in multiple sclerosis.

Recent evidence suggests that persons with multiple sclerosis may experience deficits in verbal and visuospatial acquisition rather than recall. The present study was designed to determine whether this finding generalized to a broader range of neuropsychological tests of learning and memory. To control for group differences in information acquisition, healthy controls (HCs) and persons with multiple sclerosis (MS) were trained to specific learning criteria on both verbal (i.e., paragraph learning and paired associates) and visuospatial (i.e., facial recognition) memory tasks. Persons with MS required significantly more learning trials to meet criteria on the paragraph learning and facial recognition tasks, but not the paired associates test. However, after learning comparable amounts of information, the MS and HC groups recalled statistically similar amounts of information at 30-minutes, 90-minutes, and up to 1-week on the paragraph learning and paired associate tests. This suggests that persons with MS may have deficits in acquisition rather than recall per se. Results are discussed in terms of possible rehabilitation strategies to improve memory functioning in persons with MS.

Confirmatory factor analysis of the Wechsler Memory Scale-III.

The latent structure of the Wechsler Memory Scale-III was analyzed by confirmatory factor analysis using the covariance matrix based on the 11 primary subtests from the standardization sample. Omnibus fit indexes and individual parameter estimates were examined. Of the five models evaluated, a three-factor model (working memory, auditory memory, and visual memory) provided the best fit for the standardization sample (NNFI = .98, RMSEA = .05, GFI = .98, BIC = 429.42). Models that proposed separate immediate and delayed memory constructs were hampered by inadmissible parameter estimates that signaled model specification errors. R2 values for the Faces subtests were uniformly low for all five models that suggested that this subtest has insufficient commonality with the visual memory construct.

Verbal learning subtypes in traumatic brain injury: a replication.

Traumatic brain injury (TBI) has been associated with memory impairments, but the severity and qualitative aspects of such impairment do not appear homogeneous across patients. This study sought to replicate an earlier investigation that found distinct verbal learning subtypes in TBI using the California Verbal Learning Test (CVLT). CVLT data from 88 acute rehabilitation inpatients with mild, moderate, and severe traumatic brain injuries were analyzed with multiple cluster analytic techniques. Cluster analyses yielded five learning subtypes, three of which appeared similar to the subtypes previously identified as Active, Disorganized, and Passive subtypes, and two that appeared similar to the Deficient subgroup. Traumatic brain injury appears to be characterized by heterogeneous, but fairly reliable, verbal learning subtypes that can be detected early postinjury.

The hippocampus: anatomy, pathophysiology, and regenerative capacity.

Cognitive deficits following insults to the central nervous system-particularly those involving the hippocampus and related structures-are often persistent and severely debilitating. Progress has been made in establishing the role of the hippocampus in integrating information in the formation of memory necessary for subsequent recollection of information. The present article will review anatomic, physiological, and functional aspects of the hippocampus in reference to learning and memory. Both animal and human hippocampal pathophysiological processes will be explored. Adaptive and maladaptive central nervous system responses will be reviewed, with a special emphasis on neurogenesis. Ideally, physiological and cellular compensatory responses ought to parallel clinical observation. However, this association is not clearly established. Finally, the current understanding of neuromodulatory mechanisms (although quite preliminary) will also be discussed.

Effects of coaching on detection of malingering on the California Verbal Learning Test.

The diagnostic accuracy of California Verbal Learning Test (CVLT) indices to detect malingered head injury was examined using a simulation paradigm that included naive malingerers, malingerers provided with information about head injury, and normal controls (N = 90). The application of diagnostic cutoff scores for Recognition Discriminability and Recognition Hits derived from populations of individuals with bona fide head injury and individuals suspected of malingering (Millis et al., 1995) proved highly sensitive and modestly specific in detecting feigned head injury among both simulation groups. Results of analyses of variance and logistic regression support previous findings that malingerers overestimate memory impairment associated with mild head injury; however, they indicate that exposure to a simple instructional set may render insensitive many indices of malingering. In contrast, indices based on more subtle principles of learning theory hold promise in the detection of malingering, even in the presence of an instructional set.

Verbal recall and recognition following traumatic brain injury: a [0-15]-water positron emission tomography study.

Although several studies exist which have examined static functional neuroimaging following traumatic brain injury (TBI), controlled cognitive activation studies of episodic memory in this population have not been published. The present investigation studied verbal recall using [O-15]-water positron emission tomography (PET) in 5 individuals who sustained severe TBI (M GCS=6.8; M years post-injury=3.18), and 4 non-injured control participants. Statistical image analysis demonstrated changes in frontoparietal regional cerebral blood flow (rCBF) in both groups, but there were interesting differences between groups and across conditions. Frontal lobe rCBF changes in TBI patients were reduced during free recall but enhanced during recognition, when compared to controls. Changes in cerebellar rCBF were observed in the control group during free recall, but not in the TBI sample. In both groups, bifrontal rCBF increases were noted on recognition tasks. The present findings provide evidence of alterations in specific substrates involved in verbal recall following brain injury.