Jennifer D Ryan

• PhD
• Managing Director at Baycrest

Research has documented changes in autobiographical memory and episodic future thinking in mild cognitive impairment (MCI) and Alzheimer’s disease (AD). However, cognitive decline occurs gradually and recent findings suggest that subtle alterations in autobiographical cognition may be evident earlier in the trajectory towards dementia, before AD-re...

Memory and gaze behavior are intricately linked, guiding one another to extract information and create mental representations of our environment for subsequent retrieval. Recent findings from functional neuroimaging and computational modeling suggest that reciprocal interactions between the extended hippocampal system and visuo-oculomotor regions a...

Early stages of Alzheimer's disease (AD) are associated with volume reductions in specific subregions of the medial temporal lobe (MTL). Using a manual segmentation method—the Olsen–Amaral–Palombo (OAP) protocol—previous work in healthy older adults showed that reductions in grey matter volumes in MTL subregions were associated with lower scores on...

Many species adapt to their environments by accruing relevant knowledge and expertise, which in turn shapes memory formation. Human experts remember items in their field better than novices, but different types of knowledge or exposure influence memory in different ways. By examining both expert knowledge for bird species and ecological data on env...

Autobiographical memory entails reconstructing the visual features of past events. Eye movements are associated with vivid autobiographical recollection, but this research has yet to capitalize on the high temporal resolution of eye-tracking data. We aligned eye movement data with participants’ simultaneous free recall of a verified real-life event...

Autobiographical memory entails reconstructing the visual features of past events. Eye movements are associated with vivid autobiographical recollection, but this research has yet to capitalize on the high temporal resolution of eye–tracking data. We aligned eye movement data with participants′ simultaneous free recall of a verified real–life event...

Unitization - the fusion of objects into a single unit through an action/consequence sequence - can mitigate relational memory impairments, but the circumstances under which unitization is effective are unclear. Using transverse patterning (TP), we compared unitization (and its component processes of fusion, motion, and action/consequence) with ext...

Tau pathology accumulates in the perirhinal cortex (PRC) of the medial temporal lobe (MTL) during the earliest stages of the Alzheimer's disease (AD), appearing decades before clinical diagnosis. Here, we leveraged perceptual discrimination tasks that target PRC function to detect subtle cognitive impairment even in nominally healthy older adults....

Research has documented changes in autobiographical memory and episodic future thinking in mild cognitive impairment (MCI) and Alzheimer’s disease (AD). However, cognitive decline occurs gradually and recent findings suggest that subtle alterations in autobiographical memory may be evident early in the trajectory towards dementia, before AD-related...

Research has documented changes in autobiographical memory and episodic future thinking in mild cognitive impairment (MCI) and Alzheimer’s disease (AD). However, cognitive decline occurs gradually and recent findings suggest that subtle alterations in autobiographical cognition may be evident earlier in the trajectory towards dementia, before AD-re...

Path integration (PI) is a navigation process that allows an organism to update its current location in reference to a starting point. PI computations involve updating self-position continuously with respect to the starting point (continuous updating) or creating a map representation of the route which is then used to compute the homing vector (con...

Introduction: The Transverse Patterning (TP) task has been used to measure episodic relational memory (RM) deficits in clinical populations. Individuals with schizophrenia often fail to learn TP with standard, and sometimes extensive training. Identifying the differences between TP learners and non-learners can improve our understanding of success...

Mounting evidence linking gaze reinstatement—the recapitulation of encoding-related gaze patterns during retrieval—to behavioral measures of memory suggests that eye movements play an important role in mnemonic processing. Yet, the nature of the gaze scanpath, including its informational content and neural correlates, has remained in question. In t...

Emerging evidence suggests transcranial direct current stimulation (tDCS) can improve cognitive performance in older adults. Similarly, music listening may improve arousal and stimulate subsequent performance on memory-related tasks. We examined the synergistic effects of tDCS paired with music listening on auditory neurobehavioral measures to inve...

Scene construction is a key component of memory recall, navigation, and future imagining, and relies on the medial temporal lobes (MTL). A parallel body of work suggests that eye movements may enable the imagination and construction of scenes, even in the absence of external visual input. There are vast structural and functional connections between...

The influence of prior knowledge on memory is ubiquitous, making the specific mechanisms of this relationship difficult to disentangle. Here, we show that expert knowledge produces a fundamental shift in the way that interitem similarity (i.e., the perceived resemblance between items in a set) biases episodic recognition. Within a group of expert b...

The modulation of gaze fixations on neural activity in the hippocampus, a region critical for memory, has been shown to be weaker in older adults compared to younger adults. However, as such research has relied on indirect measures of memory, it remains unclear whether the relationship between visual exploration and direct measures of memory is sim...

The use of multi-modal approaches, particularly in conjunction with multivariate analytic techniques, can enrich models of cognition, brain function, and how they change with age. Recently, multivariate approaches have been applied to the study of eye movements in a manner akin to that of neural activity (i.e., pattern similarity). Here, we review...

Background The development of dependable screening methods would allow for the early detection of incipient Alzheimer's disease (AD). Alzheimer’s pathology accumulates in the perirhinal cortex (PRC) well before diagnosis. Converging lines of research show the PRC critically contributes to object visual processing, especially when disambiguating bet...

In memory, representations of spatial features are stored in different reference frames; features relative to our position are stored egocentrically and features relative to each other are stored allocentrically. Accessing these representations engages many cognitive and neural resources, and so is susceptible to age-related breakdown. Yet, recent...

Introduction: Relational memory (RM) is severely impaired in schizophrenia. Unitisation can circumvent RM impairments in clinical populations as measured by the transverse-patterning (TP) task, a well-established measure of RM capacity. We compared memory performance on a new ecological RM measure, the Relational Trip Task (RTT), to that of TP at...

Scene construction is a key component of memory recall, navigation, and future imagining, and relies on the medial temporal lobes (MTL). A parallel body of work suggests that eye movements may enable the imagination and construction of scenes, even in the absence of external visual input. There are vast structural and functional connections between...

The ventromedial prefrontal cortex (vmPFC) is involved in diverse cognitive operations, from inhibitory control to processing of semantic schemas. When accompanied by damage to the basal forebrain, vmPFC lesions can also impair relational memory, the ability to form and recall relations among items. Impairments in establishing direct relations amon...

Listening to autobiographically-salient music (i.e., music evoking personal memories from the past), and transcranial direct current stimulation (tDCS) have each been suggested to temporarily improve older adults’ subsequent performance on memory tasks. Limited research has investigated the effects of combining both tDCS and music listening togethe...

Older adults often mistake new information as 'old', yet the mechanisms underlying this response bias remain unclear. Typically, false alarms by older adults are thought to reflect pattern completion - the retrieval of a previously encoded stimulus in response to partial input. However, other work suggests that age-related retrieval errors can be a...

Mounting evidence linking gaze reinstatement- the recapitulation of encoding-related gaze patterns during retrieval- to behavioral measures of memory suggests that eye movements play an important role in mnemonic processing. Yet, the nature of the gaze scanpath, including its informational content and neural correlates, has remained in question. In...

Episodic memory impairments in schizophrenia, including its relational memory component, are associated with significant clinical and functional variables, such as employment status, social and occupational functioning, and early and long-term remission. The Transverse Patterning (TP) task, a computer task designed to detect impairment in relationa...

How well do we know our city? It turns out, much more poorly than we might imagine. We used declarative memory and eye-tracking techniques to examine people’s ability to detect modifications of landmarks in Toronto locales with which they have had extensive experience. Participants were poor at identifying which scenes contained altered landmarks,...

There are marked individual differences in the recollection of personal past events or autobiographical memory (AM). Theory concerning the relationship between mnemonic and visual systems suggests that eye movements promote retrieval of spatiotemporal details from memory, yet assessment of this prediction within naturalistic AM has been limited. We...

Background Alterations in resting-state functional connectivity (rsFC) occur in the acute and chronic phases following traumatic brain injury (TBI); however, few studies have assessed long-term (>1 year) changes in rsFC. Methods Resting-state functional magnetic resonance imaging (rsfMRI) scans were obtained from the Federal Interagency Traumatic...

We move our eyes to explore the visual world, extract information, and create memories. The number of gaze fixations—the stops that the eyes make—has been shown to correlate with activity in the hippocampus, a region critical for memory, and with later recognition memory. Here, we combined eyetracking with fMRI to provide direct evidence for the re...

Older adults often mistake new information as ‘old’, yet, the mechanisms underlying this response bias remain unclear. Typically, false alarms by older adults are thought to reflect pattern completion – the retrieval of a previously encoded stimulus in response to partial input. However, other work suggests that age-related retrieval errors can be...

We move our eyes to explore the visual world, extract information, and create memories. The number of gaze fixations (the stops that the eyes make) has been shown to correlate with activity in the hippocampus, a region critical for memory, and with later recognition memory. Here, we combined eyetracking with fMRI to provide direct evidence for the...

The oculomotor system may be a natural and unique effector system to reveal the development and expression of memory due to its shared evolutionary history with the hippocampus that has resulted in an extensive set of structural and functional connections between the systems. Eyetracking provides a means for understanding the nature of the informat...

Local brain signal variability [SD of the BOLD signal (SDBOLD]] correlates with age and cognitive performance, and recently differentiated Alzheimer's disease (AD) patients from healthy controls. However, it is unknown whether changes to SDBOLD precede diagnosis of AD or mild cognitive impairment. We compared ostensibly healthy older adult humans w...

The ability to recall a detailed event from a simple reminder is supported by pattern completion, a cognitive operation performed by the hippocampus wherein existing mnemonic representations are retrieved from incomplete input. In behavioral studies, pattern completion is often inferred through the false endorsement of lure (i.e., similar) items as...

Visual exploration is related to activity in the hippocampus (HC) and/or extended medial temporal lobe system (MTL), is influenced by stored memories, and is altered in amnesic cases. An extensive set of polysynaptic connections exists both within and between the HC and oculomotor systems such that investigating how HC responses ultimately influenc...

Divergent thinking, an aspect of creativity, is often studied by measuring performance on the Alternative Uses Test (AUT). There is however a gap in creativity research concerning how visual stimuli on the AUT are most effectively perceived. Research in memory and attention have used eye-tracking studies to reveal insights into how people think and...

Visual exploration is related to activity in the hippocampus (HC) and/or extended medial temporal lobe system (MTL), is influenced by stored memories, and is altered in amnesic cases. An extensive set of polysynaptic connections exists both within and between the HC and oculomotor systems such that investigating how HC responses ultimately influenc...

The precise role of visual mechanisms in recollection of personal past events is unknown. The present study addresses this question from the oculomotor perspective. Participants freely recalled past episodes while viewing a blank screen under free and fixed viewing conditions. Memory performance was quantified with the Autobiographical Interview, w...

The value of case studies in informing our understanding of dissociations and interactions in memory was recognized early on by Endel Tulving, whose comprehensive work with the amnesic case K.C. helped to confirm distinctions between episodic and semantic memory. Following in this tradition, we examined memory and the use of cognitive strategies in...

Healthy older adults show impaired relational learning, but improved transitive expression when inferences are made across pre-experimentally known premise relations. Here, we used the transitivity paradigm to ask whether the organizational structure within schemas facilitates the bridging of relations for novel inference for otherwise healthy olde...

The standard systems consolidation account posits that recently formed memories are initially dependent on the hippocampus and only gradually become instantiated in neocortical networks over a period of weeks to years. However, recent animal and human research has identified rapid formation of cortical engrams at the time of learning that can suppo...

Decades of cognitive neuroscience research has shown that where we look is intimately connected to what we remember. In this article, we review findings from human and nonhuman animals, using behavioral, neuropsychological, neuroimaging, and computational modeling methods, to show that the oculomotor and hippocampal memory systems interact in a rec...

The ability to recall a detailed event from a simple reminder is supported by pattern completion, a cognitive operation performed by the hippocampus wherein existing mnemonic representations are retrieved from incomplete input. In behavioral studies, pattern completion is often inferred through the false endorsement of lure (i.e., similar) items as...

Divergent thinking, an aspect of creativity, is often studied by measuring performance on the Alternative Uses Test (AUT). There is however a gap in creativity research concerning how visual stimuli on the AUT are most effectively perceived. Research in memory and attention have used eye-tracking studies to reveal insights into how people think and...

In our daily lives we rely on prior knowledge to make predictions about the world around us such as where to search for and locate common objects. Yet, equally important in visual search is the ability to inhibit such processes when those predictions fail. Mounting evidence suggests that relative to younger adults, older adults have difficulty retr...

Eye movements support memory encoding by binding distinct elements of the visual world into coherent representations. However, the role of eye movements in memory retrieval is less clear. We propose that eye movements play a functional role in retrieval by reinstating the encoding context. By overtly shifting attention in a manner that broadly reca...

Eye movements support memory encoding by binding distinct elements of the visual world into coherent representations. However, the role of eye movements in memory retrieval is less clear. We propose that eye movements play a functional role in retrieval by reinstating the encoding context. By overtly shifting attention in a manner that broadly reca...

The lateral portion of the entorhinal cortex is one of the first brain regions affected by tau pathology, an important biomarker for Alzheimer disease. Improving our understanding of this region's cognitive role may help identify better cognitive tests for early detection of Alzheimer disease. Based on its functional connections, we tested the idea...

The comparison of memory performance during free and fixed viewing conditions has been used to demonstrate the involvement of eye movements in memory encoding and retrieval, with stronger effects at encoding than retrieval. Relative to conditions of free viewing, participants generally show reduced memory performance following sustained fixation, s...

In aging, structural and/or functional brain changes may precede changes in cognitive performance. We previously showed that despite having hippocampal volumes similar to those of younger adults, older adults showed oscillatory changes during the encoding phase of a short-delay visuospatial memory task that required spatial relations among objects...

Purpose: To investigate whether significant differences exist in everyday memory between youth with Fetal Alcohol Spectrum (FASD) compared with a nonexposed (NE) control group, while controlling for socioeconomic status and other comorbidities. Methods: Caregiver ratings using the Everyday Memory Questionnaire were obtained for 105 youth (9–17 year...

The lateral portion of the entorhinal cortex is one of the first brain regions affected by tau pathology, an important biomarker for Alzheimer's disease (AD). Improving our understanding of this region's cognitive role may help identify better cognitive tests for early detection of AD. Based on its functional connections, we tested the idea that th...

Deciphering the mechanisms underlying age-related memory declines remains an important goal in cognitive neuroscience. Recently, we observed that visual sampling behavior predicted activity within the hippocampus, a region critical for memory. In younger adults, increases in the number of gaze fixations were associated with increases in hippocampal...

Introduction: Preferential viewing of novel stimuli in the Visual Paired Comparison task has provided a useful marker of memory and medial temporal lobe function. We created a portable version of the VPC (P-VPC) and contrasted P-VPC metrics against the Montreal Cognitive Assessment (MoCA) in healthy adults, to assess the validity and reliability of...

Research using eye movement monitoring suggests that recapitulating the pattern of eye movements made during stimulus encoding at subsequent retrieval supports memory by reinstating the spatial layout of the encoded stimulus. In the present study, the authors investigated whether recapitulation of encoding fixations during a poststudy, stimulus-fre...

Half a century ago, Donald Hebb posited that mental imagery is a constructive process that emulates perception. Specifically, Hebb claimed that visual imagery results from the reactivation of neural activity associated with viewing images. He also argued that neural reactivation and imagery benefit from the re-enactment of eye movement patterns tha...

The thalamic nuclei are thought to play a critical role in recognition memory. Specifically, the anterior thalamic nuclei and medial dorsal nuclei may serve as critical output structures in distinct hippocampal and perirhinal cortex systems, respectively. Existing evidence indicates that damage to the anterior thalamic nuclei leads to impairments i...

Neuropsychological and neuroimaging findings suggest that spatial and temporal information are supported by distinct, yet overlapping networks that feed information forward to the hippocampus. Oscillatory dynamics may determine whether the hippocampus is biased towards communication with a spatial (slower frequencies) or temporal (faster frequencie...

Memory impairments are often observed in aging. Specifically, older adults have difficulty binding together disparate elements (relational memory). We have recently shown that a cognitive strategy known as unitization can mitigate impaired relational learning in the transverse patterning task (TP) in both amnesia and healthy aging. This strategy al...

Half a century ago, Donald Hebb posited that mental imagery is a constructive process that emulates perception. Specifically, Hebb claimed that visual imagery results from the reactivation of neural activity associated with viewing images. He also argued that neural reactivation and imagery benefit from the re-enactment of eye movement patterns tha...

We investigated whether older adults without subjective memory complaints, but who present with cognitive decline in the laboratory, demonstrate atrophy in medial temporal lobe (MTL) subregions associated with Alzheimer's disease. Forty community-dwelling older adults were categorized based on Montreal Cognitive Assessment (MoCA) performance. Total...

Recent functional imaging studies have proposed that the human entorhinal cortex (ERC) is subdivided into functionally distinct anterolateral (alERC) and posteromedial (pmERC) subregions. The alERC overlaps with regions that are affected earliest by Alzheimer’s disease pathology, yet its cognitive function remains poorly understood. Previous human...

In this chapter we review the behavioral and neuroimaging literature on age-related differences in hippocampal function. Although it is well known that older adults have reduced relational memory, which depends on the hippocampus, and that hippocampal volume is reduced in older adults, activity in this region is not uniformly lower in older than yo...

Contributions made by the hippocampus to long-term declarative memory are well established, but recent work compels reconsideration of the perspective that performance in other cognitive domains is independent of hippocampal function. In this chapter, we review literature that points to a role for the hippocampus in three additional domains—namely,...

Eye movements serve to accumulate information from the visual world, contributing to the formation of coherent memory representations that support cognition and behavior. The hippocampus and the oculomotor network are well connected anatomically through an extensive set of polysynaptic pathways. However, the extent to which visual sampling behavior...

Emotional arousal impairs top-down attentional control while strengthening bottom-up attentional biases. In this study, we examined whether top-down impairments due to arousal can be modulated by increasing the perceptual salience of the target stimulus. To examine this question, we briefly displayed positive and negative arousing images prior to t...

Significance statement: The hippocampal and oculomotor networks have each been extensively studied for their roles in the binding of information and gaze function, respectively. Despite the evidence that individuals with amnesia, whose damage includes the hippocampus, show alterations in their eye movement patterns, and recent findings that the tw...

Visual behavior is guided by memories from prior experience and knowledge of the visual scene. The hippocampal system (HC), in particular, has been implicated in the guidance of saccades: Amnesic patients, following damage to the HC, exhibit selective deficits in their gaze patterns. However, the neural circuitry by which mnemonic representations i...

We investigated whether older adults without subjective memory complaints, but who present with cognitive decline in the laboratory, demonstrate atrophy in medial temporal lobe (MTL) subregions associated with Alzheimer's disease. Forty community-dwelling older adults were categorized based on Montreal Cognitive Assessment (MoCA) performance. Total...

Episodic memory – composed of memory for unique spatiotemporal experiences – is known to decline with aging, and even more severely in Alzheimer ’s disease (AD). Memory for trial-unique objects in spatial scenes depends on the integrity of the hippocampus and interconnected structures that are among the first areas affected in AD. We reasoned that...

Visual search efficiency improves with repetition of a search display, yet the mechanisms behind these processing gains remain unclear. According to Scanpath Theory, memory retrieval is mediated by repetition of the pattern of eye movements or “scanpath” elicited during stimulus encoding. Using this framework, we tested the prediction that scanpath...

Context: Despite a large literature on psi, which encompasses a range of experiences including putative telepathy (mind-mind connections), clairvoyance (perceiving distant objects or events), precognition (perceiving future events), and mind-matter interactions, there has been insufficient focus on the brain in relation to this controversial pheno...

Amnesia is associated with impairments in relational memory, which is critically supported by the hippocampus. By adapting the transitivity paradigm, we previously showed that age-related impairments in inference were mitigated when judgments could be predicated on known pairwise relations, however such advantages were not observed in the adult-ons...

Episodic memories are comprised of details of “where” and “when”; spatial and temporal relations, respectively. However, evidence from behavioural, neuropsychological, and neuroimaging studies has provided mixed interpretations about how memories for spatial and temporal relations are organised—they may be hierarchical, fully interactive, or indepe...

Binding relations among items in the transverse patterning (TP) task is dependent on the integrity of the hippocampus and its extended network. Older adults have impaired TP learning, corresponding to age-related reductions in hippocampal volumes. Unitization is a training strategy that can mitigate TP impairments in amnesia by reducing reliance on...

Binding relations among items in the transverse patterning (TP) task is dependent on the integrity of the hippocampus and its extended network. Older adults have impaired TP learning, corresponding to age-related reductions in hippocampal volumes. Unitization is a training strategy that can mitigate TP impairments in amnesia by reducing reliance on...

Recent models of hippocampal function have emphasized its role in relational binding - the ability to form lasting representations regarding the relations among distinct elements or items which can support memory performance, even over brief delays (e.g., several seconds). The present study examined the extent to which aging is associated with chan...

From Immanuel Kant to the present, “schemas” have been a central tenet of memory research. Schemas are associative knowledge structures that are abstracted from specific learning experiences and are subsequently used to give meaning to incoming sensory information. Schemas serve to efficiently integrate new experiences into existing knowledge store...

Visual stimulus repetition has been shown to improve processing efficiency and performance on recognition memory tasks. According to scanpath theory, memory-based repetition effects are mediated by repetition of the pattern of fixations or "scanpath" elicited during stimulus encoding at subsequent retrieval. However, it remains unclear how scanpath...

Aging has been associated with a decline in relational memory, which is critically supported by the hippocampus. By adapting the transitivity paradigm (Bunsey & Eichenbaum, 1996), which traditionally has been used in non-human animal research, this work examined the extent to which aging is accompanied by deficits in relational learning and flexibl...

Recently, the amnesic case D.A. was shown to circumvent his relational memory impairments, as observed in the transverse patterning (TP) task, using a self-generated unitization strategy, and such performance benefits were maintained over extended delays (Ryan, Moses, Barense, & Rosenbaum, 2013). 'Unitization' encourages fusing of distinct items, t...

Objective This study provides insight into the thoughts and opinions of geriatric health-care professionals toward cognitive assessments and the use of emerging technologies, such as eye-tracking, to supplement current tools. Methods Two focus group sessions were conducted with nurses and physicians who routinely administer neurocognitive assessme...

Current theories state that the hippocampus is responsible for the formation of memory representations regarding relations, whereas extrahippocampal cortical regions support representations for single items. However, findings of impaired item memory in hippocampal amnesics suggest a more nuanced role for the hippocampus in item memory. The hippocam...

The onset of dementia is preceded by biological changes in the brain over a course of years to decades. Early detection of these changes is essential to effective intervention. Early abnormalities may include changes in the brain’s electrical activity. We used magnetoencephalography (MEG) to characterize the brain’s electromagnetic responses to lan...

The processing of emotional as compared to neutral information is associated with different patterns in eye movement and neural activity. However, the ‘emotionality’ of a stimulus can be conveyed not only by its physical properties, but also by the information that is presented with it. There is very limited work examining the how emotional informa...

We tested the hypothesis that active exploration of the visual environment is mediated not only by visual attention but also by visual working memory (VWM) by examining performance in both a visual search and a change detection task. Subjects rarely fixated previously-examined distracters during visual search, suggesting that they successfully reta...