Because maximizing the learning of new material is a relevant concern for most individuals, understanding the specific processes involved could be beneficial for people of all ages. Both encoding and monitoring occur during the learning acquisition phase, yet monitoring accuracy and subsequent neural activation have been relatively ignored in the literature. The current research adapts a common metacognitive paradigm using Judgments of Learning (JOLs) to explore the neural differences in monitoring between younger (18-25) and older (65+) adults. Participants were asked to remember natural scenes and predict encoding success by providing a JOL response for each item. Participants were told to respond “will remember” if they believed they would remember that item on a later recognition memory test or “will forget” if they thought they would forget that item on a later recognition memory test. Actual memory performance was compared to predicted memory performance to provide a measure of monitoring accuracy. Individuals reported a JOL response for 150 intact (Easy) and 150 scrambled (Difficult) scenes while in a 3.0T fMRI scanner. Despite minimal differences in behavioral performance, there were several age-related neuroimaging findings of note. When compared to younger adults, older adults had decreases in medial temporal lobe (MTL) activation, as well as contralateral recruitment of the anterior cingulate. Most importantly, the present study also disambiguated structures related to encoding success (the right parahippocampus) and monitoring accuracy (the anterior cingulate). A novel account of neural structures that mediate monitoring is provided both across items varying in difficulty (Easy and Difficult) and across different age groups (Young and Old). Encoding and monitoring are important for learning acquisition and the present research provides the first account that successfully disambiguates the two processes. Results are discussed in reference to their educational implications on resource allocation during the learning of new material.

The wake human brain constantly samples perceptual information from the environment and integrates them into existing neuronal networks. Neuronal oscillations have been ascribed a key role in the formation of novel memories. The theta rhythm (3-8 Hz) reflects a central executive mechanism, which integrates novel information, reflected in theta-coupled gamma oscillations (> 30 Hz). Alpha oscillations (8-14 Hz) reflect an attentional gating mechanism, which inhibit task irrelevant neuronal processes. In my dissertation I further scrutinized the oscillatory dynamics of memory formation. Study 1 demonstrated that theta-gamma coupling reflects a specific mechanism for associative memory formation. In study 2, I experimentally entrained memory encoding by visual evoked theta-gamma coupling processes, to underline its functional relevance. In two developmental studies, I found that the theta rhythm indexes explicit learning processes in adults and young children (study 3), and that visually entrained theta oscillations are sensitive to the encoding of novel, unexpected events, already in the first year of life (study 4). Throughout these studies alpha oscillations were not sensitive to memory formation processes, but indicated perceptual (study 1) and semantic (study 3) processes. I propose an integrative framework, suggesting that the alpha rhythm reflects activated semantic representations in the neocortex, while theta-gamma coupling reflects an explicit mnemonic control mechanism, which selects, elaborates and integrates activated representations. Specifically, by squeezing real time events onto a faster, neuronal time scale, theta-gamma coding facilitates neuronal plasticity in medio-temporal networks and advances neuronal processes ahead of real time to emulate and guide future behavior.

<p>Navigation is a very important area of spatial information research that presents researchers with a number of challenges. One of these challenges concerns the nature of spatial information encoding itself: is such encoding the result of a single mechanism system, a two-mechanism system or possibly a mixed system? One possible avenue of insight into this problem centers on the disorientation effect as described in Wang & Spelke (2000). A quick survey of basic findings, terminating with Waller & Hodgson (2006), indicates that there seem to be two systems at work. Moreover, the results obtained are based upon experiments carried out in actual reality. A virtual reality experiment was designed in an attempt to replicate the findings described in Waller & Hodgson (2006). The experiment is described in detail and its results are presented. These were found to be sufficiently reliable to justify pointing to a potentially rich field for future research, including such techniques as combining VR with fMRI to achieve more fine-grained results that cannot currently be obtained from the direct use of actual reality only. Underlying factors such as experimental control and data presentation are briefly described in the discussion section.</p> / Master of Science (MS)

The processes of pattern separation and pattern completion are very important in the correct discrimination of similar memories. Much research has been conducted on these processes, but there are some gaps that need to be addressed. First, there is some debate as to whether false alarms to lure items come about because of a failure to accurately encode a memory or a failure to retrieve a memory. Second, much of the research on pattern separation and pattern completion in humans is done with visual stimuli and contributions of stimulus modality to these processes are not well understood as a result.Study 1 consisted of three experiments conducted using a combination of eye tracking and functional magnetic resonance imaging (fMRI) methods. Analyses of eye tracking data in the experiments examined the contribution of fixation counts at encoding and retrieval, as well as target-lure similarity level, to accuracy on lure trials. Task designs were altered across studies to attempt to replicate specific research previously conducted with a specific answer period, as well as generalize the findings to a broader body of research that allows participants to answer while the stimulus is presented. The three experiments showed mixed support for the contribution of fixation counts at encoding and retrieval to the accurate discrimination of similar lures. Target- lure similarity, however, was a robust predictor of accuracy for all three experiments.Prior research examining activity in the hippocampus demonstrates a reduction of fMRI activity to repetitions of a stimulus. Greater activity is also observed in the dentate gyrus/CA3 (DG/CA3) subregions for correct rejections of lure items compared to lure false alarms. There should be a greater reduction in the DG/CA3 as a function of encoding for lure false alarms than for lure correct rejections if memory encoding drives the activity differences between these outcomes. The fMRI data showed a marked reduction of activity in the left hippocampus to repetition trials as a function of encoding trial fixation count. There was no significant difference between activity as a function of encoding fixation count in the DG/CA3 for lure correct rejections and lure false alarms. There was also no difference in activity for the CA1 either. Overall, the results of the eye tracking and fMRI data give support for the contribution of pattern completion to false alarms to lure stimuli rather than poor encoding.Study 2 examined the contribution of sensory modality to accurate discriminations of lure stimuli. A behavioral task was developed to directly compare discrimination of similar lures on visual and auditory stimuli. Participants were significantly more accurate and more confident of their responses when discriminating visual stimuli as compared to discriminating auditory stimuli.

Recent proposals have attributed a key role to novelty in the formation of new episodic memories. These proposals are based on evidence of enhanced memory and greater metabolic activity in the hippocampus in response to novel relative to familiar materials. However, such novelty effects are incongruous with long-standing observations that familiar items and lists are associated with better memory than novel ones. In four experiments, I explored possible reasons for this apparent discrepancy. In Experiment 1, I directly tested whether previously observed novelty effects were the result of novelty, discrimination demands, or both. I used linguistic materials (proverbs) to replicate the novelty effect but found it occurred only when familiar items were subject to source confusion. In Experiment 2, to examine better how novelty influences episodic memory, I used experimentally familiar, pre-experimentally familiar, and novel proverbs in a paradigm designed to overcome discrimination demand confounds. Memory was better for both types of familiar proverbs. These cognitive results indicate that familiarity, not novelty, leads to better episodic memory for studied items, regardless of whether familiarity is experimentally induced or based on prior knowledge. I also conducted two fMRI experiments to evaluate the neural correlates of the encoding of novel and familiar forms of information. In Experiment 3, I compared the neural encoding correlates of source memory for novel and familiar visual scenes using fMRI. Replicating previous neuroimaging studies, I observed an anterior novelty-sensitive region of the hippocampus specialized in novelty encoding. Unlike past studies, I also probed for familiarity-encoding regions and identified such regions in the posterior hippocampus. I replicated this pattern in Experiment 4 using proverbs as stimuli. As in Experiment 2, I found the effect held whether familiarity was based on prior knowledge or experimental induction. In both fMRI experiments, anterior and posterior hippocampal regions were functionally connected with different large-scale networks, helping to explain local variation in hippocampal functional specialization in terms of different neural contexts. Together, these experiments show that stimulus familiarity enhances episodic memory for materials, and that novelty is processed differently, not preferentially, in the hippocampus. A new model of hippocampal novelty processing is proposed.

Recent proposals have attributed a key role to novelty in the formation of new episodic memories. These proposals are based on evidence of enhanced memory and greater metabolic activity in the hippocampus in response to novel relative to familiar materials. However, such novelty effects are incongruous with long-standing observations that familiar items and lists are associated with better memory than novel ones. In four experiments, I explored possible reasons for this apparent discrepancy. In Experiment 1, I directly tested whether previously observed novelty effects were the result of novelty, discrimination demands, or both. I used linguistic materials (proverbs) to replicate the novelty effect but found it occurred only when familiar items were subject to source confusion. In Experiment 2, to examine better how novelty influences episodic memory, I used experimentally familiar, pre-experimentally familiar, and novel proverbs in a paradigm designed to overcome discrimination demand confounds. Memory was better for both types of familiar proverbs. These cognitive results indicate that familiarity, not novelty, leads to better episodic memory for studied items, regardless of whether familiarity is experimentally induced or based on prior knowledge. I also conducted two fMRI experiments to evaluate the neural correlates of the encoding of novel and familiar forms of information. In Experiment 3, I compared the neural encoding correlates of source memory for novel and familiar visual scenes using fMRI. Replicating previous neuroimaging studies, I observed an anterior novelty-sensitive region of the hippocampus specialized in novelty encoding. Unlike past studies, I also probed for familiarity-encoding regions and identified such regions in the posterior hippocampus. I replicated this pattern in Experiment 4 using proverbs as stimuli. As in Experiment 2, I found the effect held whether familiarity was based on prior knowledge or experimental induction. In both fMRI experiments, anterior and posterior hippocampal regions were functionally connected with different large-scale networks, helping to explain local variation in hippocampal functional specialization in terms of different neural contexts. Together, these experiments show that stimulus familiarity enhances episodic memory for materials, and that novelty is processed differently, not preferentially, in the hippocampus. A new model of hippocampal novelty processing is proposed.

As the amount of computer mediated information (e.g., emails, documents, multi-media) we need to process grows, our need to rapidly sort, organize and store electronic information likewise increases. In order to store information effectively, we must find ways to sort through it and organize it in a manner that facilitates efficient retrieval. The instantaneous and emergent nature of communications across networks like Twitter makes them suitable for discussing events (e.g., natural disasters) that are amorphous and prone to rapid changes. It can be difficult for an individual human to filter through and organize the large amounts of information that can pass through these types of social networks when events are unfolding rapidly. A common feature of social networks is the images (e.g., human faces, inanimate objects) that are often used by those who send messages across these networks. Humans have a particularly strong ability to recognize and differentiate between human Faces. This effect may also extend to recalling information associated with each human Face. This study investigated the difference between human Face images, non-human Face images and alphanumeric labels as retrieval cues under different levels of Task Load. Participants were required to recall key pieces of event information as they emerged from a Twitter-style message feed during a simulated natural disaster. A counter-balanced within-subjects design was used for this experiment. Participants were exposed to low, medium and high Task Load while responding to five different types of recall cues: (1) Nickname, (2) Non-Face, (3) Non-Face & Nickname, (4) Face and (5) Face & Nickname. The task required participants to organize information regarding emergencies (e.g., car accidents) from a Twitter-style message feed. The messages reported various events such as fires occurring around a fictional city. Each message was associated with a different recall cue type, depending on the experimental condition. Following the task, participants were asked to recall the information associated with one of the cues they worked with during the task. Results indicate that under medium and high Task Load, both Non-Face and Face retrieval cues increased recall performance over Nickname alone with Non-Faces resulting in the highest mean recall scores. When comparing medium to high Task Load: Face & Nickname and Non-Face significantly outperformed the Face condition. The performance in Non-Face & Nickname was significantly better than Face & Nickname. No significant difference was found between Non-Faces and Non-Faces & Nickname. Subjective Task Load scores indicate that participants experienced lower mental workload when using Non-Face cues than using Nickname or Face cues. Generally, these results indicate that under medium and high Task Load levels, images outperformed alphanumeric nicknames, Non-Face images outperformed Face images, and combining alphanumeric nicknames with images may have offered a significant performance advantage only when the image is that of a Face. Both theoretical and practical design implications are provided from these findings.