Biomedical subjects

Katherine Sledge Moore

Publications and source records attributed to Katherine Sledge Moore.

4 recordsLinked to original sources

PubMed2006

Working memory for conjunctions relies on the medial temporal lobe.

A prominent theory of hippocampal function proposes that the hippocampus is importantly involved in relating or binding together separate pieces of information to form an episodic representation. This hypothesis has only been applied to studies of long-term memory because the paradigmatic view of the hippocampus is that it is not critical for short-term forms of memory. However, relational processing is important in many working memory tasks, especially tasks using visual stimuli. Here, we test the hypothesis that the medial temporal lobes are important for relational memory even over short delays. The task required patients with medial temporal lobe amnesia and controls to remember three objects, locations, or object-location conjunctions over 1 or 8 s delays. The results show that working memory for objects and locations was at normal levels, but that memory for conjunctions was severely impaired at 8 s delays. Additional analyses suggest that the hippocampus per se is critical for accurate conjunction working memory. We propose that the hippocampus is critically involved in memory for conjunctions at both short and long delays.

Aged↗

PubMed2006

Using perfusion fMRI to measure continuous changes in neural activity with learning.

In this study, we examine the suitability of a relatively new imaging technique, arterial spin labeled perfusion imaging, for the study of continuous, gradual changes in neural activity. Unlike BOLD imaging, the perfusion signal is stable over long time-scales, allowing for accurate assessment of continuous performance. In addition, perfusion fMRI provides an absolute measure of blood flow so signal changes can be interpreted without reference to a baseline. The task we used was the serial response time task, a sequence learning task. Our results show reliable correlations between performance improvements and decreases in blood flow in premotor cortex and the inferior parietal lobe, supporting the model that learning procedures that increase efficiency of processing will be reflected in lower metabolic needs in tissues that support such processes. More generally, our results show that perfusion fMRI may be applied to the study of mental operations that produce gradual changes in neural activity.

Adolescent↗

PubMed2006

Visual working memory is impaired when the medial temporal lobe is damaged.

The canonical description of the role of the medial temporal lobes (MTLs) in memory is that short-term forms of memory (e.g., working memory [WM]) are spared when the MTL is damaged, but longer term forms of memory are impaired. Tests used to assess this have typically had a heavy verbal component, potentially allowing explicit rehearsal strategies to maintain the WM trace over the memory delay period. Here we test the hypothesis that the MTL is necessary for visual WM when verbal rehearsal strategies are difficult to implement. In three patients with MTL damage we found impairments in spatial, face, and color WM, at delays as short as 4 sec. Impaired memory could not be attributed to memory load or perceptual problems. These findings suggest that the MTLs are critical for accurate visual WM.

Aged↗

PubMed2005

Associative learning improves visual working memory performance.

The ability to remember visual stimuli over a short delay period is limited by the small capacity of visual working memory (VWM). Here the authors investigate the role of learning in enhancing VWM. Participants saw 2 spatial arrays separated by a 1-s interval. The 2 arrays were identical except for 1 location. Participants had to detect the difference. Unknown to the participants, some spatial arrays would repeat once every dozen trials or so for up to 32 repetitions. Spatial VWM performance increased significantly when the same location changed across display repetitions, but not at all when different locations changed from one display repetition to another. The authors suggest that a major role of learning in VWM is to mediate which information gets retained, rather than to directly increase VWM capacity.

Adolescent↗