The effect of interference on temporal order memory in individuals with Parkinson's disease

Impaired spatial pattern separation performance in temporal lobe epilepsy is associated with visuospatial memory deficits and hippocampal volume loss

Individuals with chronic temporal lobe epilepsy (TLE) experience episodic memory deficits that may be progressive in nature. These memory decrements have been shown to increase with the extent of hippocampal damage, a hallmark feature of TLE. Pattern separation, a neural computational mechanism thought to play a role in episodic memory formation, has been shown to be negatively affected by aging and in individuals with known hippocampal dysfunction. Despite the link between poor pattern separation performance and episodic memory deficits, behavioral pattern separation has not been examined in patients with TLE. We examined pattern separation performance in a group of 22 patients with medically-refractory TLE and 20 healthy adults, using a task hypothesized to measure spatial pattern separation with graded levels of spatial interference. We found that individuals with TLE showed less efficient spatial pattern separation performance relative to healthy adults. Poorer spatial pattern separation performance in TLE was associated with poorer visuospatial memory, but only under high interference conditions. In addition, left hippocampal atrophy was associated with poor performance in the high interference condition in TLE. These data suggest that episodic memory impairments in patients with chronic, refractory TLE may be partially due to less efficient pattern separation, which likely reflects their underlying hippocampal dysfunction.

The Misinformation Effect and the Type of Misinformation: Objects and the Temporal Structure of an Episode

This study aimed to modify the stimulus set used to test the misinformation effect developed by Takarangi and her colleagues. The narratives and memory tests were modified to include items asking about specific objects in the story and about the temporal structure of the events. To examine whether the new material could produce the misinformation effect, the author had 72 participants watch a video, read a narrative with misinformation about objects in the video or the temporal sequence in the video, and then take a memory recognition test. This study showed that the misinformation effect could be produced by the temporal misinformation, suggesting that participants were misled by the misinformation regardless of the type of misinformation. As a result of using the modified narratives and the memory test, researchers could examine the effects of multiple types of misinformation.