Many college students struggle to perform well on exams in the early morning. Although students drink caffeinated beverages to feel more awake, it is unclear whether these actually improve performance. After consuming coffee (caffeinated or decaffeinated), college-age adults completed implicit and explicit memory tasks in the early morning and late afternoon (Experiment 1). During the morning, participants ingesting caffeine demonstrated a striking improvement in explicit memory, but not implicit memory. Caffeine did not alter memory performance in the afternoon. In Experiment 2, participants engaged in cardiovascular exercise in order to examine whether increases in physiological arousal similarly improved memory. Despite clear increases in physiological arousal, exercise did not improve memory performance compared to a stretching control condition. These results suggest that caffeine has a specific benefit for memory during students’ non-optimal time of day – early morning. These findings have real-world implications for students taking morning exams.

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Although people do not normally try to remember associations between faces and physical contexts, these associations are established automatically, as indicated by the difficulty of recognizing familiar faces in different contexts (“butcher-on-the-bus” phenomenon). The present functional MRI (fMRI) study investigated the automatic binding of faces and scenes. In the Face-Face (F-F) condition, faces were presented alone during both encoding and retrieval, whereas in the Face/Scene-Face (FS-F) condition, they were presented overlaid on scenes during encoding but alone during retrieval (context change). Although participants were instructed to focus only on the faces during both encoding and retrieval, recognition performance was worse in the FS-F than the F-F condition (“context shift decrement”—CSD), confirming automatic face-scene binding during encoding. This binding was mediated by the hippocampus as indicated by greater subsequent memory effects (remembered > forgotten) in this region for the FS-F than the F-F condition. Scene memory was mediated by the right parahippocampal cortex, which was reactivated during successful retrieval when the faces were associated with a scene during encoding (FS-F condition). Analyses using the CSD as a regressor yielded a clear hemispheric asymmetry in medial temporal lobe activity during encoding: left hippocampal and parahippocampal activity was associated with a smaller CSD, indicating more flexible memory representations immune to context changes, whereas right hippocampal/rhinal activity was associated with a larger CSD, indicating less flexible representations sensitive to context change. Taken together, the results clarify the neural mechanisms of context effects on face recognition.

Previous studies have attributed declining episodic memory in increased adult age to less efficient contextual markers that are typically associated with ventromedial prefrontal cortex function (e.g., Allen et al., 2005). However, this previous research found the link only for negative affect. Ashby, Isen, and Turken (1999) predicted that individual differences in positive affect should also have an impact on cognitive performance. The present study therefore extended our earlier work on negative affect to positive affect and showed that individual differences in NEO Extraversion scores (a proxy for affective intensity) moderated age differences in episodic memory. Older adults with lower extraversion scores performed more poorly on a test of long-term memory (the Rey Auditory Verbal Learning Task* RAVLT) than did older adults with high extroversion scores. Yet no such effect was found on a test of short-term memory (RAVLT Trial 1). Furthermore, restricting analyses to those high in extraversion (i.e., high affective intensity) eliminate age effects on long-term memory. We propose that adult age is often characterised by a decline in affective intensity (sometimes resulting in weaker positive affective states), which might lead to encoding of fewer/weaker contextual markers at study, which then impairs later recall from long-term memory.

Objective Soroxchi/Acute Mountain Sickness (AMS) is a condition that can result in cerebral and pulmonary hypoxia. Neuropsychological research on AMS is minimal and the long-term effects on cognition and behavior are unclear. AMS is associated with cognitive impairments in processing speed, attention, and executive functions as well as neurobehavioral symptoms. This case study delineates the neuropsychological and neurobehavioral changes secondary to bilateral globus pallidus (GP) lesions associated with AMS. Case Description Patient is a 51-year old, primarily Spanish-speaking, male of Mexican descent with 9 years of education, and who had traveled to La Paz, Bolivia (4,070 MASL) for work. Upon arrival, fatigue and dizziness led to hospitalization to treat acute pulmonary edema and hypoxia. Brain MRI revealed hyperintense bilateral GP lesions. Medical history was notable for hyperlipidemia. Psychiatric history was unremarkable. Neuropsychological assessment 4 months post-AMS revealed impairments in visuo-conceptual and speeded complex visuospatial abilities, executive functions, and confrontation naming. Cognitive improvements were noted in delayed recall of non-contextual verbal information and confrontation naming ten months post-AMS. Significant mood and personality changes were reported; patient endorsed anhedonia, fatigue, alexithymia, avolition, and sleep difficulties. Family described patient as depressed, apathetic, and socially withdrawn. Pharmacological and psychotherapy treatments were recommended and initiated. Diagnostic Impressions and Outcomes Findings were consistent with a diagnosis of Mild Neurocognitive Disorder. His family denied neurobehavioral improvements post interventions. Discussion This case study is the first to characterize the long-term neuropsychological and neurobehavioral changes following bilateral GP lesions secondary to AMS. Declines in visual-conceptual abilities reveal a new finding for this type of cerebral incident.