Effects of sleep on positive, negative and neutral valenced story and image memory

During sleep, emotional memories are preferentially strengthened. However, most studies on sleep and emotional memory focus on comparing negative valence with neutral valence stimuli. This study compared the sleep‐dependent memory effects for stories and images, each comprising negative, neutral, and positive stimuli. It was hypothesized that a sleep effect would be seen for negatively and positively valenced stimuli. A novel story memory task (comprising three stories), and photographs from the Nencki Affective Picture database were presented for learning to 61 healthy adults (ages 18–25). They were tested for memory on the two tasks immediately, and then again after either a 2‐hr nap (n = 31; 17 women, 14 men) or 2‐hr wake period (n = 30; 13 women, 17 men). At second testing, the sleep condition had significantly better recall compared to the wake condition on both tasks. There was a relationship with valence only for the story task, with better performance for the sleep condition on the negatively and positively valenced texts, but not on the neutral text. There were no significant relationships between memory measures and sleep‐stage duration and EEG power variables. The story memory findings support the hypothesis that memory consolidation prioritizes emotional memory, whether positively or negatively valenced.

Immediate story recall in elderly individuals with memory complaints: how much does it contribute to memory assessment?

BACKGROUND

Prose memory tests exhibit ecological validity, but the influence of non-memory functions on immediate recall in elderly subjects with memory complaints has not been fully investigated. This study examined (1) whether the ability to immediately recall a story can distinguish among clinical controls, amnesic mild cognitive impairment (MCI) and dementia due to Alzheimer's disease (AD) and (2) which cognitive functions contribute to immediate recall performance.

METHODS

A total of 73 consecutive volunteers (50 women and 23 men) aged 47-88 (mean age = 71.85 ± 9.41) and with a mean schooling level of 12.51 (SD = 4.09) participated in the experiment. All individuals were seeking specialized evaluation because of memory complaints. Diagnoses were made by considering clinical, neuropsychological, and MRI assessments collected by a multidisciplinary team of neurologists, neuropsychologists, and speech-language therapists. A total of 26 individuals were classified as clinical controls; 27 as MCI patients; and 20 as having AD dementia. All individuals in the AD group had a Clinical Dementia Rating (CDR) ≤ 1.

RESULTS

Immediate recall was only able to distinguish AD subjects from MCI patients and clinical controls (p > 0.05). Stepwise multiple linear regression analysis revealed that mental status (MMSE), semantic memory (WAIS-III vocabulary) and episodic memory (RAVLT primacy) explained approximately 62% of the variance in immediate recall.

CONCLUSIONS

Understanding the value and limitations of immediate story recall in distinguishing between MCI and AD may help clinicians in better choosing cognitive tests to diagnose MCI.

Entorhinal cortex volume in older adults: reliability and validity considerations for three published measurement protocols

Measuring the entorhinal cortex (ERC) is challenging due to lateral border discrimination from the perirhinal cortex. From a sample of 39 nondemented older adults who completed volumetric image scans and verbal memory indices, we examined reliability and validity concerns for three ERC protocols with different lateral boundary guidelines (i.e., Goncharova, Dickerson, Stoub, & deToledo-Morrell, 2001; Honeycutt et al., 1998; Insausti et al., 1998). We used three novice raters to assess inter-rater reliability on a subset of scans (216 total ERCs), with the entire dataset measured by one rater with strong intra-rater reliability on each technique (234 total ERCs). We found moderate to strong inter-rater reliability for two techniques with consistent ERC lateral boundary endpoints (Goncharova, Honeycutt), with negligible to moderate reliability for the technique requiring consideration of collateral sulcal depth (Insausti). Left ERC and story memory associations were moderate and positive for two techniques designed to exclude the perirhinal cortex (Insausti, Goncharova), with the Insausti technique continuing to explain 10% of memory score variance after additionally controlling for depression symptom severity. Right ERC-story memory associations were nonexistent after excluding an outlier. Researchers are encouraged to consider challenges of rater training for ERC techniques and how lateral boundary endpoints may impact structure-function associations.