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Biomedical subjects

M L Albert

Publications and source records attributed to M L Albert.

At least 73 records · Page 4Linked to original sources
PubMed1984

Changes in cerebral lateralization in aging.

To determine whether there is increasing left hemispheric lateralization for language with age and whether the right hemisphere is selectively impaired with advanced age, we tested 96 right-handed people aged 25-80 yr on verbal and non-verbal matching tasks presented tachistoscopically. Task difficulties was equalized by adjusting exposure durations. Exposure duration, error laterality and response latency laterality were analyzed. Typical field effects as well as age-related slowing and sex by task interactions were observed. However, no systematic age-related changes in lateralization were apparent.

Adult↗
PubMed1984

Varieties of perseveration.

We propose a new taxonomy for perseveration consisting of three categories which are distinctive at the levels of clinical features, process, and neuroanatomy. Stuck-in-set perseveration, the inappropriate maintenance of a current category or framework, involves an underlying process deficit in executive functioning and is related neuroanatomically to frontal lobe damage. Recurrent perseveration, the unintentional repetition of a previous response to a subsequent stimulus, involves an abnormal post-facilitation of memory traces and is related neuroanatomically to posterior left hemisphere damage. Continuous perseveration is the inappropriate prolongation or repetition of a behavior without interruption. It involves a deficit in motor output and is most common in patients with damage to the basal ganglia.

Aged↗
PubMed1983

Early changes in material properties of rabbit articular cartilage after meniscectomy.

We have correlated early material and biochemical changes in articular cartilage in a surgical model for cartilage degeneration. Medial meniscectomy was performed on the left knee of 17 adult, female New Zealand white rabbits. The equilibrium Young's modulus of cartilage was assessed by an indentation test in situ at defined sites on the medial and lateral tibial plateaus of the operated and control knees; the cartilage was then excised and analyzed biochemically. Focal changes were consistently observed in the medial surface of the operated knee. The equilibrium modulus and the glycosaminoglycan content fell rapidly, reaching a minimum by 2 weeks after surgery; the lateral tibial surface was essentially unaffected. Six months after surgery, the glycosaminoglycan content had returned to normal and the modulus to near normal. Independent measurements on cored plugs from the medial surface 2 weeks after surgery revealed a significant decrease in both the dynamic stiffness and the streaming potential in the operated knee compared with the control. The findings suggest that normal ambulatory loads in vivo will deform the affected medial cartilage much more than normal. It remains to be seen if altered mechanical stresses are solely responsible for initiating and sustaining matrix remodeling by the chondrocytes.

Animals↗
PubMed1983

The effect of increasing age on the latency for saccadic eye movements.

The latency for saccadic eye movements to a visual stimulus was studied in 59 adults whose ages ranged from 20.7 to 79.5 years. All were free of neurologic disease and drug use. Horizontal eye movements were recorded by electrooculography and the latency from the onset of a peripheral visual stimulus to the onset of a saccadic refixation eye movement was determined. A linear regression analysis revealed a correlation between increasing age and increasing latency for saccadic refixation eye movements. The direct relationship between increasing age and increasing latency for saccadic eye movements is a factor that should be taken into account in eye-movement studies as well as other methodologies such as tachistoscopic studies in which saccadic eye movements play a role in study design.

Adult↗
PubMed1982

Pure word deafness. Analysis of a case with bilateral lesions and a defect at the prephonemic level.

We have demonstrated that the deficit in speech perception in our patient with pure word deafness is secondary to a prephonemic temporal auditory acuity disorder. We delineated the nature of the auditory processing deficit in our patient with bilateral lesions and then demonstrated the presence of a predicted deficit in phonemic discrimination. This pattern is comparable to previous cases with bilateral lesions and distinct from other cases with unilateral lesions. Review of previous reports suggests that there are two distinct types of pure word deafness: type 1, in which the deficit is prephonemic and related to a temporal auditory acuity disorder, and type 2, a form that is independent of a temporal auditory acuity disorder, and has a deficit in linguistic discrimination that does not adhere to a prephonemic pattern (Denes and Semenza, 1975; Saffran et al., 1976). The former has been associated with bilateral temporal lobe lesions (Naeser, 1974; Chocholle et al., 1975), the latter with left unilateral lesions (Denes and Semenza, 1975; Saffran et al., 1976). The first form is an apperceptive disorder, whereas the second represents a higher disorder in phonemic discrimination and may be considered a fragment of Wernicke's aphasia.

Agnosia↗
PubMed1979

The anatomic basis of visual agnosia.

In a patient with associative visual agnosia without alexia, there was bilateral infarction in the distribution of the posterior cerebral arteries, with corticosubcortical lesions in both occipitotemporal regions, sparing the corpus callosum. Bilateral loss of visual-limbic connections may underlie associative visual agnosia, and bilateral lesions of the inferior longitudinal fasciculi may be the necessary and sufficient lesions for this syndrome. Alexia was absent in this case, perhaps because the corpus callosum was intact.

Agnosia↗
PubMed1976

Cerebral dominance for consciousness.

In a prospective study we evaluated the relationship of level of consciousness to hemispheric side of lesion following acute cerebrovascular injury. Fifty-seven percent of patients with left hemispheric lesions had initial impairment of consciousness, in contrast to 25% with right-sided damage.

Cerebrovascular Disorders↗
PubMed1975

Comprehending a word: the influence of speed and redundancy on auditory comprehension in aphasia.

To assess the contribution of various factors to comprehension of a target word, an auditory comprehension test was devised and administered to a series of aphasic patients. Patients were required to select from an array that picture which corresponded to a spoken target word. Each patient heard the target word under five conditions: (1) target spoken alone; (2) target embedded in a neutral (low redundancy) sentence enunciated at a normal rate of speaking; (3) target in a neutral sentence enunciated at a slow rate of speaking; (4) target embedded in a sentence containing semantic support (high redundancy); (5) target embedded in a sentence containing a semantically-deceptive element. Semantic redundancy and rate of presentation made contributions to comprehensibility. Semantic confusions were prevalent among all aphasics but, contrary to earlier reports, posterior patients were especially prone to acoustic confusions. Except for conduction aphasics, patients were more likely to confuse words which began with the same sounds than words which ended with the same sounds. Patients with adequate comprehension at the start of the testing displayed a uniform tendency to improve on the conditions administered later, while those with impaired comprehension at the start usually did not.

Aphasia↗
PubMed1975

Hemianopic colour blindness.

A man developed cortical blindness after cerebral infarction in the distribution of both posterior cerebral arteries. When he recovered from this condition, he was found to be colour blind in the left visual field, but not in the right. This unusual situation resulted in apparently contradictory performances on hemifield and free-field tasks of colour discrimination, naming, and recognition. The contradictions may be explained by interhemispheric competition between a hemisphere which could discriminate colours and a hemisphere which was colour blind.

Agnosia↗
PubMed1975

Associative visual agnosia without alexia.

A brain-damaged man was unable to appreciate the nature of objects and meaningful nonverbal symbols presented visually, although he could see, draw, describe, and match these stimuli. He had no difficulty understanding visually presented words. Auditory and tactile recognition of both verbal and nonverbal stimuli were normal. Our findings provide evidence that two neuropsychologic mechanisms were responsible for this disorder. One was an interhemispheric visual-verbal disconnection; the other was a specific categorization defect for visual, nonverba, meaningful stimuli. Neither mechanism alone was sufficient; both were necessary.

Agnosia↗