Biomedical subjects

S Sahrmann

Publications and source records attributed to S Sahrmann.

5 recordsLinked to original sources

PubMed1999

Motor dysfunction in mildly demented AD individuals without extrapyramidal signs.

BACKGROUND: Although not as prominent as cognitive decline, motor dysfunction occurs in AD, particularly in the later stages of the disease. OBJECTIVE: To determine whether early-stage AD is also characterized by motor impairment. METHODS: We examined very mildly (Clinical Dementia Rating [CDR] 0.5) and mildly (CDR 1) demented AD individuals in comparison with healthy elderly control individuals (CDR 0) on a variety of nonmotor cognitive and psychomotor measures and on four motor measures (gait velocity, finger tapping, reaction time, movement time). To minimize the possibility of extrapyramidal dysfunction contaminating the groups, only individuals who were clinically free of extrapyramidal signs were included in the study. RESULTS: Mildly demented AD individuals were slowed on all motor measures except for finger tapping. No evidence of motor dysfunction was found in the very mildly demented AD group. As expected, both AD groups were impaired on the nonmotor cognitive and psychomotor tests. CONCLUSIONS: These results indicate that AD alone, in the absence of clinically confirmed extrapyramidal dysfunction, is associated with motor slowing in a stage-dependent manner. It remains to be determined whether this motor slowing represents a general characteristic of mild AD or indicates other neuropathology such as PD or the Lewy body variant of AD.

Aged↗

PubMed1998

Cognitive and motor functioning in Parkinson disease: subjects with and without questionable dementia.

BACKGROUND: The nature of cognitive performance in subjects with Parkinson disease (PD) without dementia is controversial, perhaps because of failure to exclude subjects with unrecognized very mild dementia. OBJECTIVE: To compare cognitive and motor functioning in well-characterized subjects with PD without overt dementia with healthy elderly control subjects. DESIGN: Subjects' conditions were evaluated clinically and psychometrically at entry into a longitudinal study of cognitive and motor performance in elderly subjects. Measures included a global dementia staging scale, the Washington University Clinical Dementia Rating; psychometric tests, including Logical Memory, Digit Span, Associate Learning, Information, Block Design, Digit Symbol, Trail-making A, Crossing-off, Boston Naming Test, and Word Fluency; and motor measures, including finger tapping, gait velocity, reaction time, and movement time. SETTING: A university-based research facility. SUBJECTS: There were 3 groups of subjects: healthy elderly control subjects (n=43), subjects with PD without dementia (n=58), and subjects with PD with questionable dementia (n=22), each evaluated at time of entry. RESULTS: As expected, both PD groups were impaired on motor measures (gait velocity, finger tapping, and movement time) compared with the healthy elderly control group. Neither PD group showed slowing in reaction time. The subjects with PD with questionable dementia were more impaired on Logical Memory, Block Design, Digit Symbol, and Trailmaking A compared with the subjects with PD without dementia. Although free of clinically evident cognitive dysfunction (Clinical Dementia Rating score, 0), the PD group without dementia was impaired with respect to the healthy elderly control group on all measures from the psychometric assessment except Digit Span, Associate Learning, and Word Fluency. CONCLUSIONS: The PD group without dementia showed global cognitive impairments in comparison with the healthy elderly control group, possibly because the healthy elderly control subjects represented idealized aging. Although the deficits were of small magnitude, this finding suggests that PD may predispose to subclinical cognitive impairment. Longitudinal follow-up is required to determine whether subjects with PD destined to develop overt dementia can be distinguished from those who do not.

Aged↗

PubMed1998

Relationship between standing posture and stability.

BACKGROUND AND PURPOSE: This study determined whether persons with stability impairments have postural aberrations. We investigated whole-body posture and its relationship to center-of-gravity (COG) stability. SUBJECTS: Data from 27 subjects with vestibular hypofunction and 26 subjects without vestibular impairment were analyzed. METHOD: An optoelectronic full-body system measured kinematics. Force plates measured ground reaction forces while subjects stood with their feet 30 cm apart and eyes open and with their feet together and eyes closed. RESULTS: The subjects with vestibular hypofunction demonstrated less stability than the subjects without impairment, but there were no postural differences. Subjects with vestibular hypofunction had more weight on the left lower extremity during standing with feet apart. In all subjects in both groups, during standing with feet apart, the COG was anterior to the ankle, knee, back, and shoulder and posterior to the hip and neck. Subjects had an anterior pelvic tilt, extended trunk and head, right laterally flexed trunk and pelvis, and flexed knees. With their feet together, subjects increased their anterior pelvic tilt; trunk, head, and knee flexion; and anterior COG position. CONCLUSION AND DISCUSSION: Posture and stability had a low correlation. Subjects with bilateral vestibular hypofunction did not demonstrate a forward head or backward trunk lean, as has been reported anecdotally. Changing from standing with feet apart to feet together increased whole-body movement patterns to control standing stability.

Adult↗

PubMed1993

DPT controversy.

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Education, Graduate↗

PubMed1992

Neuronal multipotentiality: evidence for network representation of physiological function.

Extracellular action potentials of single neurons in motor cortex and rectified and integrated electromyographic activity (EMG) of gastrocnemius and anterior tibialis were recorded while a monkey performed isometric ankle plantar and dorsal flexion tasks. This study determined the consistency of neuronal behaviors across different tasks. Methods characterized neuronal behaviors by determining which behavioral event within a single task, such as the appearance of the 'go' signal, force onset, or agonist and antagonist EMG onset, was best related to changes in neuronal activity. Another method compared the temporal profiles of discharge modulation across different tasks. Of 220 neurons recorded, 44 were selected because they were consistently active in the tasks. Of these, 37 were in the precentral cortex and the remaining seven were in the postcentral cortex. Only 14 of the 33 in motor cortex were consistent in their behavioral correlations. Several had multiple changes in activity within a single task that were related to different behavioral events. Half were consistent for direction of force and a third were consistent for magnitude of force. Furthermore, there was little consistency in the temporal profiles of discharge activity for all 44 neurons across tasks. Similar modulations of discharge activity among neurons in one task were different in another task. Such inconsistencies are evidence against the cardinal cell hypothesis of physiological representation. We offer a new hypothesis analogous to connectionism in parallel distributed processing.

Action Potentials↗