Neha Sinha

Prospect Pricing in Cognitive Radio Networks

Advances in cognitive radio networks have primarily focused on the design of spectrally agile radios and novel spectrum sharing techniques that are founded on expected utility theory (EUT). In this paper, we consider the development of novel spectrum sharing algorithms in such networks taking into account human psychological behavior of the end-users, which often deviates from EUT. Specifically, we consider the impact of end-user decision making on pricing and management of radio resources in a cognitive radio enabled network when there is uncertainty in the quality of service (QoS) guarantees offered by the service provider (SP). Using prospect theory (a Nobel-Prize-winning behavioral economic theory that captures human decision making and its deviation from EUT), we design data pricing and channel allocation algorithms for use in cognitive radio networks by formulating a game theoretic analysis of the interplay between the price offerings, bandwidth allocation by the SP, and the service choices made by end-users. We show that, when the end-users under-weight the service guarantee, they tend to reject the offer, which results in under-utilization of radio resources and revenue loss. We propose prospect pricing, a pricing mechanism that can make the system robust to decision making and improve radio resource management. We present analytical results as well as preliminary human subject studies with video QoS.

Multiple-Choice Questioning Is an Efficient Instructional Methodology That May Be Widely Implemented in Academic Courses to Improve Exam Performance

Distributed multiple-choice questioning during instruction improves exam performance in middle-school and college classes. Instructional multiple-choice questioning is effective whether done in class or online and improves performance on short-answer and free-recall exam questions as well as multiple-choice questions. It may improve performance on exam questions about facts not previously queried.

Delayed, But Not Immediate, Feedback After Multiple-Choice Questions Increases Performance on a Subsequent Short-Answer, But Not Multiple-Choice, Exam: Evidence for the Dual-Process Theory of Memory

ABSTRACT Three experiments, two performed in the laboratory and one embedded in a college psychology lecture course, investigated the effects of immediate versus delayed feedback following a multiple-choice exam on subsequent short answer and multiple-choice exams. Performance on the subsequent multiple-choice exam was not affected by the timing of the feedback on the prior exam; however, performance on the subsequent short answer exam was better following delayed than following immediate feedback. This was true regardless of the order in which immediate versus delayed feedback was given. Furthermore, delayed feedback only had a greater effect than immediate feedback on subsequent short answer performance following correct, confident responses on the prior exam. These results indicate that delayed feedback cues a students prior response and increases subsequent recollection of that response. The practical implication is that delayed feedback is better than immediate feedback during academic testing.

Baseline Levels of Rapid-Eye-Movement Sleep May Protect Against Excessive Activity in Fear-Related Neural Circuitry

Sleep, and particularly rapid eye movement sleep (REM), has been implicated in the modulation of neural activity following fear conditioning and extinction in both human and animal studies. It has long been presumed that such effects play a role in the formation and persistence of posttraumatic stress disorder, of which sleep impairments are a core feature. However, to date, few studies have thoroughly examined the potential effects of sleep prior to conditioning on subsequent acquisition of fear learning in humans. Furthermore, these studies have been restricted to analyzing the effects of a single night of sleep—thus assuming a state-like relationship between the two. In the current study, we used long-term mobile sleep monitoring and functional neuroimaging (fMRI) to explore whether trait-like variations in sleep patterns, measured in advance in both male and female participants, predict subsequent patterns of neural activity during fear learning. Our results indicate that higher baseline levels of REM sleep predict reduced fear-related activity in, and connectivity between, the hippocampus, amygdala and ventromedial PFC during conditioning. Additionally, skin conductance responses (SCRs) were weakly correlated to the activity in the amygdala. Conversely, there was no direct correlation between REM sleep and SCRs, indicating that REM may only modulate fear acquisition indirectly. In a follow-up experiment, we show that these results are replicable, though to a lesser extent, when measuring sleep over a single night just before conditioning. As such, baseline sleep parameters may be able to serve as biomarkers for resilience, or lack thereof, to trauma. SIGNIFICANCE STATEMENT Numerous studies over the past two decades have established a clear role of sleep in fear-learning processes. However, previous work has focused on the effects of sleep following fear acquisition, thus neglecting the potential effects of baseline sleep levels on the acquisition itself. The current study provides the first evidence in humans of such an effect. Specifically, the results of this study suggest that baseline rapid eye movement (REM) sleep may serve a protective function against enhanced fear encoding through the modulation of connectivity between the hippocampus, amygdala, and the ventromedial PFC. Building on this finding, baseline REM measurements may serve as a noninvasive biomarker for resilience to trauma or, conversely, to the potential development of posttraumatic stress disorder following trauma.

The Effect of a Final Exam on Long-Term Retention

ABSTRACT Testing on a final exam in a college course improved long-term retention over material that had not been tested on the final. Students from an upper level psychology course took a long-term retention test, four to five months after the end of the course. For half of the items, a related question had been on the final. For the remaining half, a related question had appeared on an earlier exam, but not the final. On the long-term retention test, percent correct was 79% when a related question had appeared on the final and 67% when a related question had not appeared on the final. These results have both theoretical and practical implications.

Providing the answers does not improve performance on a college final exam

In the context of an upper-level psychology course, even when students were given an opportunity to refer to text containing the answers and change their exam responses in order to improve their exam scores, their performance on these questions improved slightly or not at all. Four experiments evaluated competing explanations for the students’ failure to correct their answers. Experiments 1–3 ruled out ceiling effects, cognitive bias from a previous response and item selection effects, respectively, as explanations of the result. Experiment 4 showed that no more than 41% of the students comprehended the paragraphs well enough to find the answer. Furthermore, even this 41% of the students did not put sufficient effort into finding the answer, regardless of the impact on their grade, when they were not coerced to do so.

APOE ε4 Status in Healthy Older African Americans is Associated with Deficits in Pattern Separation and Hippocampal Hyperactivation

African Americans are 1.4 times more likely than European Americans to carry the apolipoprotein E (APOE) ε4 allele, a risk factor for Alzheimers disease (AD). However, little is known about the neural correlates of cognitive function in older African Americans and how they relate to genetic risk for AD. In particular, no past study on African Americans has examined the effect of APOE ε4 status on pattern separation-mnemonic discrimination performance and its corresponding neural computations in the hippocampus. Previous work using the mnemonic discrimination paradigm has localized increased activation in the DG/CA3 hippocampal subregions as being correlated with discrimination deficits. In a case-control high-resolution functional magnetic resonance imaging study of 30 healthy African Americans, aged 60 years and older, we observed APOE ε4-related impairments in mnemonic discrimination, coincident with dysfunctional hyperactivation in the DG/CA3, and CA1 regions, despite no evidence of structural differences in the hippocampus between carriers and noncarriers. Our results add to the growing body of evidence that deficits in pattern separation may be an early marker for AD-related neuronal dysfunction.

Classroom instruction results in better exam performance than online instruction in a hybrid course

Abstract The purpose of this experiment was to determine whether performance on a subsequent exam was affected when two lessons were as similar as possible except that one was presented in class and the other was presented online. In a hybrid course, half of the lessons were presented in the classroom as narrated Power Point presentations and half of the lessons were presented online as narrated Power Point presentations. Online student–teacher interaction took place in a chatroom. Furthermore, for each question on the midterm or final examination, the students had answered a pre-lesson and post-lesson question, integrated with the appropriate lesson, which queried the same fact statement as the exam question. Students performed better on post-lesson questions asked in class than post-lesson questions asked online. They also performed better on exam questions on classroom lessons than exam questions on online lessons. The results support the conclusion that social interaction aids learning.

ABCA7 Risk Variant in Healthy Older African Americans is Associated with a Functionally Isolated Entorhinal Cortex Mediating Deficient Generalization of Prior Discrimination Training

Using high‐resolution resting state functional magnetic resonance imaging (fMRI), the present study tested the hypothesis that ABCA7 genetic risk differentially affects intra‐medial temporal lobe (MTL) functional connectivity between MTL subfields, versus internetwork connectivity of the MTL with the medial prefrontal cortex (mPFC), in nondemented older African Americans. Although the association of ABCA7 risk variants with Alzheimers disease (AD) has been confirmed worldwide, its effect size on the relative odds of being diagnosed with AD is significantly higher in African Americans. However, little is known about the neural correlates of cognitive function in older African Americans and how they relate to AD risk conferred by ABCA7. In a case–control fMRI study of 36 healthy African Americans, we observed ABCA7 related impairments in behavioral generalization that was mediated by dissociation in entorhinal cortex (EC) resting state functional connectivity. Specifically, ABCA7 risk variant was associated with EC‐hippocampus hyper‐synchronization and EC‐mPFC hypo‐synchronization. Carriers of the risk genotype also had a significantly smaller anterolateral EC, despite our finding no group differences on standardized neuropsychological tests. Our findings suggest a model where impaired cortical connectivity leads to a more functionally isolated EC at rest, which translates into aberrant EC‐hippocampus hyper‐synchronization resulting in generalization deficits. While we cannot identify the exact mechanism underlying the observed alterations in EC structure and network function, considering the relevance of Aβ in ABCA7 related AD pathogenesis, the results of our study may reflect the synergistic reinforcement between amyloid and tau pathology in the EC, which significantly increases tau‐induced neuronal loss and accelerates synaptic alterations. Finally, our results add to a growing literature suggesting that generalization of learning may be a useful tool for assessing the mild cognitive deficits seen in the earliest phases of prodromal AD, even before the more commonly reported deficits in episodic memory arise.

Dissociating Medial Temporal and Striatal Memory Systems With a Same/Different Matching Task: Evidence for Two Neural Systems in Human Recognition

ABSTRACT The medial temporal lobe and striatum have both been implicated as brain substrates of memory and learning. Here, we show dissociation between these two memory systems using a same/different matching task, in which subjects judged whether four-letter strings were the same or different. Different RT was determined by the left-to-right location of the first letter different between the study and test string, consistent with a left-to-right comparison of the study and test strings, terminating when a difference was found. This comparison process results in same responses being slower than different responses. Nevertheless, same responses were faster than different responses. Same responses were associated with hippocampus activation. Different responses were associated with both caudate and hippocampus activation. These findings are consistent with the dual-system hypothesis of mammalian memory and extend the model to human visual recognition.