Biomedical subjects

C Elsinger

Publications and source records attributed to C Elsinger.

3 recordsLinked to original sources

PubMed2006

fMRI study of episodic memory in relapsing-remitting MS: correlation with T2 lesion volume.

OBJECTIVE: To determine whether memory loss in patients with multiple sclerosis (MS) results from faulty encoding or retrieval, we correlated extent of T2-weighted lesion involvement with brain activation patterns on fMRI scans obtained while patients performed a verbal episodic memory task. METHODS: We performed a neurologic examination, neuropsychological testing, and an event-related fMRI scan on 36 patients with relapsing-remitting MS. In addition, we obtained T2-weighted structural MRI scans to measure lesion volume. We performed a regression analysis to examine the association between lesion volume and regional brain activation. RESULTS: Increasing lesion volume correlated with increasing magnitude of brain activation, primarily in the left frontal and parietal association cortices. Significant correlations of function with lesion volume were primarily observed during the memory retrieval phase of the task. CONCLUSIONS: These results extend previous fMRI studies in multiple sclerosis (MS) by demonstrating an association between greater disease burden and increased neural recruitment during episodic memory. In addition, the stronger correlations observed between lesion volume and brain activation during retrieval than encoding would suggest that retrieval processes are more affected by MS-related cerebral pathology.

Adult↗

PubMed2001

Timing and reaction time.

Because reaction time (RT) tasks are generally repetitive and temporally regular, participants may use timing strategies that affect response speed and accuracy. This hypothesis was tested in 3 serial choice RT experiments in which participants were presented with stimuli that sometimes arrived earlier or later than normal. RTs increased and errors decreased when stimuli came earlier than normal, and RTs decreased and errors increased when stimuli came later than normal. The results were consistent with an elaboration of R. Ratcliff's diffusion model (R. Ratcliff, 1978; R. Ratcliff & J. N. Rouder, 1998; R. Ratcliff, T. Van Zandt, & G. McKoon, 1999), supplemented by a hypothesis developed by D. Laming (1979a, 1979b), according to which participants initiate stimulus sampling before the onset of the stimulus at a time governed by an internal timekeeper. The success of this model suggests that timing is used in the service of decision making.

Adolescent↗

PubMed1999

Approaching grasping from different perspectives.

The hypothesis introduced by Smeets and Brenner concerning the perpendicular approach of the thumb and index finger during grasping has heuristic value, but it also has limitations. Among the limitations are the following: (a) the approach parameter is not directly testable and it is unclear how the values of deceleration at contact and movement time are set theoretically; (b) it is questionable that motion of the thumb and index finger are independent; (c) reliance on the minimum-jerk account ignores critiques of that account; and (d) the model begs the question of how the effectors proximal to the index finger and thumb are controlled. We briefly review an alternative model that can handle these challenges.

Biomechanical Phenomena↗