Biomedical subjects

K Y Haaland

Publications and source records attributed to K Y Haaland.

10 recordsLinked to original sources

PubMed1992

Introduction to the special section on the emotional concomitants of brain damage.

The purpose of this introduction is to emphasize the theoretical and clinical implications of studying emotion after brain damage. Theoretically, it is one way of elucidating critical neural substrates of emotion and the interaction of cognitive and noncognitive determinants. Clinically, the cognitive and other behavioral changes associated with certain types of brain damage may make traditional methods of assessing emotion inaccurate. This special section is designed to review current knowledge regarding these issues and to emphasize their theoretical and clinical importance.

Adult↗

PubMed1992

Skill learning in the elderly: diminished implicit and explicit memory for a motor sequence.

Explicit and implicit memory for a cognitive-motor sequence was studied in elderly and young adults. Implicit memory was examined in a serial reaction-time paradigm in which sequences of hand postures repeated cyclically, then shifted to random sequences. Two control groups received random sequences throughout. Movement times (MTs) across the first 4 blocks did not improve more in the elderly-repeated than in the elderly-random group. In contrast, the young-repeated group showed greater improvement in MT across these blocks than the young-random group. MT was less affected in the elderly than in the young by shifts between repeated and random sequences, indicating impaired implicit memory. Explicit memory, which was assessed by free recall and cued recall, also was impaired in the elderly. Diminished implicit memory in the elderly could not be explained solely by the possible intrusion of conscious recollection strategies.

Adult↗

PubMed1992

Motor sequencing with left hemisphere damage. Are some cognitive deficits specific to limb apraxia?

Sixteen left-hemisphere stroke patients, who were apraxic or nonapraxic, and 17 control subjects performed sequences of hand postures that varied in the number of different postures (repetitive and heterogeneous) and sequence length (one to five). Performance of the left hand (ipsilateral to stroke) was compared with a control group using the left hand. All stroke patients had slower reaction times and were slower to execute single hand postures, but the apraxic group was not slower than the nonapraxic group. Both the apraxic and the nonapraxic groups had similar problems scheduling or timing motor programs for both sequence types such that inter-response times were more affected by sequence length than the control group. However, only the apraxic group showed abnormalities in preprogramming heterogeneous sequences. The apraxic group also made more errors and had longer movement times (MTs) than for the other groups, but only for heterogeneous sequences containing more than three hand postures. The nonapraxic group did not show slower MTs or greater errors, regardless of the type or the length of sequences. These results suggested deficits in encoding, generating single movements and in scheduling or timing a series of actions which generally attributable to left hemisphere damage. However, abnormalities in temporal organization processes prior to and during movement were specific to apraxia. The dissociation between the two stroke groups on some but not all aspects of sequencing has implications for different cognitive mechanisms supporting motor sequencing.

Aged↗

PubMed1991

Hemispheric specialization for motor sequencing: abnormalities in levels of programming.

Left and right hemisphere stroke patients and control subjects performed sequences of hand postures which varied in complexity (repetitive and heterogeneous) and length (one to five). Performance in the hand ipsilateral to the stroke was compared to a control group using the same hand. Neither stroke group had problems preprogramming sequences prior to movement. The only deficit seen for the right hemisphere group was a greater difference in movement time (MT) between heterogeneous and repetitive sequences relative to controls, regardless of sequence length. This suggested right hemisphere damage results in subtle timing but not error deficits on more complex movements, perhaps due to increased external spatial demands. The left hemisphere group was slower to execute single postures, and had difficulty scheduling motor programs for repetitive and heterogeneous movements such that inter-response times (IRTs) were more affected by sequence length than for controls. Left hemisphere patients also made more errors on heterogeneous sequences as they increased in length, and the difference in MTs between repetitive and heterogeneous sequences increased more with increasing length relative to their control group. These results suggested the left hemisphere plays a role in controlling single postures, in scheduling motor programs during repetitive and heterogeneous movements, and in processes related to sequential ordering.

Aged↗

PubMed1991

Hearing and cognition in the elderly. New findings and a review of the literature.

The purpose of this study was to determine the relationship between hearing status and cognitive status initially and at 5-year follow-up in a cohort of healthy elderly men and women and to relate the results to published reports on this topic. Volunteers older than 60 years with no major illnesses and taking no long-term prescription medications were examined. Baseline testing of hearing and cognition was performed in 224 subjects; 112 subjects underwent cognitive testing at 5-year follow-up. Hearing was measured by the Speech Perception in Noise test; cognition was measured by two parts of the Wechsler Memory Scale and by the Jacobs Cognitive Screening Test, an oral screening instrument. At baseline there were small correlations between hearing acuity and memory scores, but these disappeared after adjustment for age and gender. Analysis of follow-up memory and cognitive screening test scores in relation to baseline hearing ability showed no correlation between hearing at entry and cognitive function at 5 years. In addition, baseline hearing level did not predict change in memory or cognitive screening test scores during the follow-up period. The power of the study was 90% to detect a correlation of .30 between measures of hearing and cognition. There was no evidence for a major effect of hearing acuity on cognitive function over time in this group of healthy elderly. Review of published studies suggests that hearing ability is related to cognitive status in demented subjects, but there is little to suggest that in the normal elderly, hearing impairment leads to cognitive decline.

Aged↗

PubMed1991

Sequencing in Parkinson's disease. Abnormalities in programming and controlling movement.

Central programming deficits in Parkinson's disease (PD) were studied in two reaction time (RT) experiments. In Experiment 1, PD patients and controls performed sequences of hand postures that varied in length, the number of different postures (repetitive vs heterogeneous), and the delay interval before movement. Before movement, the PD group planned repetitive movements like controls whereas for heterogeneous sequences RT increased less with sequence length for the PD group, implying less preprogramming. The interresponse time (IRT) data from repetitive sequences showed that the PD group had difficulty controlling movement such that IRTs were faster when sequences were longer, thus allowing more time to schedule the termination of the sequence during the course of movement. For heterogeneous sequences, the PD group made more errors and were slower than controls when changing hand postures, suggesting a deficit in switching between different responses. While RT decreased with a longer delay similarly for both groups, IRT1 continued to improve only for the PD group but similarly for both types of sequences, suggesting a deficit specific to programming the first response. In Experiment 2, subjects made decisions about the number of different hand postures contained within a sequence. PD patients' decision times improved more with a longer delay only for heterogeneous sequences, suggesting a problem in identifying the number of different hand postures. The results have implications for levels of motor dysfunction in PD which emphasize the influence of sequence length and complexity.

Aged↗

PubMed1990

Procedural memory in Parkinson's disease: impaired motor but not visuoperceptual learning.

A current model proposes that memory consists of two functionally separate systems that have different neurological substrates. Declarative memory appears to be dependent on the diencephalic medial temporal lobe system whereas some speculate that the basal ganglia may be a neurological substrate for procedural memory. This study tested the role of the basal ganglia in regulating different types of procedural skills by comparing performance on a motor and a visuoperceptual skill learning task. Twenty Parkinson's (PD) patients and 20 normal control subjects performed two procedural learning tasks (rotary pursuit and mirror reading) and one declarative learning task (paired associates) over 3 days. The results showed that PD patients were not impaired on mirror reading or paired associate learning. On rotary pursuit, performance levels on day 1 were similar between groups, but the PD group showed less improvement across days than controls. However, only patients with more advanced symptoms of PD showed impaired rotary pursuit learning, and this could not be attributed directly to deficits in primary motor or general cognitive function. These findings suggest that the underlying processes/procedures for procedural learning are specific to the task, and are supported by different neuroanatomical systems.

Attention↗

PubMed1979

The effect of symptom duration on cognitive and motor performance in parkinsonism.

Neuropsychologic test performance was examined in a normal control group and in three groups of Parkinson disease patients, with symptoms for 2 years or less, for 3 to 5 years, or for 6 to 15 years. On a test battery sampling a wide variety of cognitive and motor abilities, significant intergroup differences occurred primarily on tasks with a primary motor component, although mild intergroup cognitive impairment was also demonstrated. The results suggested that maximal deterioration occurred during the first 5 years of symptoms, with few significant additional changes after that.

Attention↗

PubMed1977

Motor performance after unilateral hemisphere damage in patients with tumor.

Hemispheric asymmetry of sensory-motor control has been hypothesized on the basis of clinical and experimental data, but discrepant data indicate asymmetry may vary with task requirements. To examine this possibility, the performance of normal controls and patients with right or left hemispheric tumors were compared on a variety of motor tasks of varying complexity. Group differences were significant only for the two most complex of six tasks; since these two tasks differ in quality (proximal steadiness and distal dexterity), it is unlikely that quality differences are crucial. On these tasks, the group with left hemisphere damage demonstrated bilateral impairment while the right hemisphere group's deficits were contralateral to lesion site. These results support previous data and Liepmann's hypothesis of hemispheric asymmetry of sensory-motor control. Task complexity and the more specific hypothesis of sensory-motor sequencing are important factors influencing hemispheric asymmetry of control.

Adult↗

PubMed1976

Interhemispheric EEG activity in normal and aphasic adults.

EEG recordings were obtained from 10 normal and 10 aphasic adults while they participated in behavioral tasks and a no performance condition. Interhemispheric asymmetry and average activity at 5 to 15 Hz in each hemisphere were compared between groups and among tasks. Asymmetry during behavioral tasks did not differ significantly between groups or among tasks, however, aphasic patients showed a significant decrease in average activity at 5 to 15 Hz on the behavioral tasks compared with the level for a non performance condition. Test-retest reliability was poor for asymmetry but acceptable for average activity at 5 to 15 Hz. Finally, asymmetry was significantly related with severity of aphasia.

Aged↗