scholarly journals Pupillometry as a Glimpse into the Neurochemical Basis of Human Memory Encoding

2015 ◽  
Vol 27 (4) ◽  
pp. 765-774 ◽  
Author(s):  
Russell Cohen Hoffing ◽  
Aaron R. Seitz
Keyword(s):  
Locus Coeruleus ◽  
Pupil Size ◽  
Ethical Issues ◽  
Human Memory ◽  
Memory Encoding ◽  
Learning Paradigm ◽  
Surrogate Measure ◽  
Second Procedure ◽  
Task Irrelevant ◽  
The Brain

Neurochemical systems are well studied in animal learning; however, ethical issues limit methodologies to explore these systems in humans. Pupillometry provides a glimpse into the brain's neurochemical systems, where pupil dynamics in monkeys have been linked with locus coeruleus (LC) activity, which releases norepinephrine (NE) throughout the brain. Here, we use pupil dynamics as a surrogate measure of neurochemical activity to explore the hypothesis that NE is involved in modulating memory encoding. We examine this using a task-irrelevant learning paradigm in which learning is boosted for stimuli temporally paired with task targets. We show that participants better recognize images that are paired with task targets than distractors and, in correspondence, that pupil size changes more for target-paired than distractor-paired images. To further investigate the hypothesis that NE nonspecifically guides learning for stimuli that are present with its release, a second procedure was used that employed an unexpected sound to activate the LC–NE system and induce pupil-size changes; results indicated a corresponding increase in memorization of images paired with the unexpected sounds. Together, these results suggest a relationship between the LC–NE system, pupil-size changes, and human memory encoding.

scholarly journals When encodong yields remembering: insights from event-related neuroimaging

1999 ◽  
Vol 354 (1387) ◽  
pp. 1307-1324 ◽  
Author(s):  
Anthony D. Wagner ◽  
Wilma Koutstaal ◽  
Daniel L. Schacter
Keyword(s):  
Neural Activity ◽  
Functional Neuroimaging ◽  
Event Related Potentials ◽  
Human Memory ◽  
Memory Encoding ◽  
Positron Emission ◽  
Related Potentials ◽  
The Rich ◽  
Dm Effect ◽  
The Brain

To understand human memory, it is important to determine why some experiences are remembered whereas others are forgotten. Until recently, insights into the neural bases of human memory encoding, the processes by which information is transformed into an enduring memory trace, have primarily been derived from neuropsychological studies of humans with select brain lesions. The advent of functional neuroimaging methods, such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), has provided a new opportunity to gain additional understanding of how the brain supports memory formation. Importantly, the recent development of event–related fMRI methods now allows for examination of trial–by–trial differences in neural activity during encoding and of the consequences of these differences for later remembering. In this review, we consider the contributions of PET and fMRI studies to the understanding of memory encoding, placing a particular emphasis on recent event–related fMRI studies of the Dm effect: that is, differences in neural activity during encoding that are related to differences in subsequent memory. We then turn our attention to the rich literature on the Dm effect that has emerged from studies using event–related potentials (ERPs). It is hoped that the integration of findings from ERP studies, which offer higher temporal resolution, with those from event–related fMRI studies, which offer higher spatial resolution, will shed new light on when and why encoding yields subsequent remembering.

scholarly journals Noradrenergic projections from the locus coeruleus to the amygdala constrain auditory fear memory reconsolidation

2020 ◽  
Author(s):  
Josue Haubrich ◽  
Matteo Bernabo ◽  
Karim Nader
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Locus Coeruleus ◽  
Molecular Mechanisms ◽  
Fear Memory ◽  
Memory Formation ◽  
Memory Reconsolidation ◽  
Memory Encoding ◽  
Memory Strength ◽  
The Brain

ABSTRACTMemory reconsolidation is a fundamental plasticity process in the brain that allows established memories to be changed or erased. However, certain boundary conditions limit the parameters under which memories can be made plastic. Strong memories do not destabilize, for instance, although why they are resilient is mostly unknown. Here, we extend the understanding of the mechanisms implicated in reconsolidation-resistant memories by investigating the hypothesis that specific modulatory signals shape memory formation into a state that lacks lability. We find that the activation of the noradrenaline-locus coeruleus system (NOR-LC) during strong fear memory encoding increases molecular mechanisms of stability at the expense of lability in the amygdala. Preventing the NOR-LC from modulating strong fear encoding results in the formation of memories that can undergo reconsolidation within the amygdala and thus are vulnerable to post-reactivation interference. Thus, the memory strength boundary condition on reconsolidation is set at the time of encoding by the action of the NOR-LC.

scholarly journals Pupil size as a window on neural substrates of cognition

2019 ◽  
Author(s):  
Siddhartha Joshi ◽  
Joshua I Gold
Keyword(s):  
Superior Colliculus ◽  
Locus Coeruleus ◽  
Pupil Size ◽  
Neural Substrates ◽  
Neural Dynamics ◽  
Cognitive Tasks ◽  
Non Invasive ◽  
Open Questions ◽  
Neural Underpinnings ◽  
The Brain

Pupil modulations provide a non-invasive window onto how the brain performs many cognitive tasks. Here we review recent work that has begun to identify specific neural underpinnings of these cognitively driven pupil signals, including key roles for: 1) the superior colliculus (SC), which mediates responses to salient stimuli that evoke orienting responses; and 2) the locus coeruleus (LC), the source of a major neuromodulator (norepinephrine) that mediates arousal and cognition. We discuss how these findings can inform the interpretation of pupil measurements in terms of specific neural operations involving the SC and LC. We also highlight caveats, open questions, and key future experiments for improving the interpretation of pupil measurements in terms of the underlying neural dynamics throughout the brain.

scholarly journals Noradrenergic projections from the locus coeruleus to the amygdala constrain fear memory reconsolidation

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Josué Haubrich ◽  
Matteo Bernabo ◽  
Karim Nader
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Locus Coeruleus ◽  
Molecular Mechanisms ◽  
Fear Memory ◽  
Memory Formation ◽  
Memory Reconsolidation ◽  
Memory Encoding ◽  
Memory Strength ◽  
The Brain

Memory reconsolidation is a fundamental plasticity process in the brain that allows established memories to be changed or erased. However, certain boundary conditions limit the parameters under which memories can be made plastic. Strong memories do not destabilize, for instance, although why they are resilient is mostly unknown. Here, we investigated the hypothesis that specific modulatory signals shape memory formation into a state that is reconsolidation-resistant. We find that the activation of the noradrenaline-locus coeruleus system (NOR-LC) during strong fear memory encoding increases molecular mechanisms of stability at the expense of lability in the amygdala of rats. Preventing the NOR-LC from modulating strong fear encoding results in the formation of memories that can undergo reconsolidation within the amygdala and thus are vulnerable to post-reactivation interference. Thus, the memory strength boundary condition on reconsolidation is set at the time of encoding by the action of the NOR-LC.

Confronting the grey zone after severe brain injury

2019 ◽  
Vol 3 (6) ◽  
pp. 707-711 ◽  
Author(s):  
Andrew Peterson ◽  
Adrian M. Owen
Keyword(s):  
Brain Injury ◽  
Ethical Issues ◽  
Vegetative State ◽  
Clinical Care ◽  
Grey Zone ◽  
Severe Brain Injury ◽  
New Methods ◽  
Legal Decision Making ◽  
Technological Developments ◽  
The Brain

In recent years, rapid technological developments in the field of neuroimaging have provided several new methods for revealing thoughts, actions and intentions based solely on the pattern of activity that is observed in the brain. In specialized centres, these methods are now being employed routinely to assess residual cognition, detect consciousness and even communicate with some behaviorally non-responsive patients who clinically appear to be comatose or in a vegetative state. In this article, we consider some of the ethical issues raised by these developments and the profound implications they have for clinical care, diagnosis, prognosis and medical-legal decision-making after severe brain injury.

Neuroethics

2017 ◽  
Keyword(s):  
Brain Function ◽  
Ethical Issues ◽  
Wearable Technologies ◽  
Definition Of Death ◽  
Populations At Risk ◽  
The Future ◽  
Aging Adults ◽  
Definition Of ◽  
The Brain ◽  
New Criteria

We have new answers to how the brain works and tools which can now monitor and manipulate brain function. Rapid advances in neuroscience raise critical questions with which society must grapple. What new balances must be struck between diagnosis and prediction, and invasive and noninvasive interventions? Are new criteria needed for the clinical definition of death in cases where individuals are eligible for organ donation? How will new mobile and wearable technologies affect the future of growing children and aging adults? To what extent is society responsible for protecting populations at risk from environmental neurotoxins? As data from emerging technologies converge and are made available on public databases, what frameworks and policies will maximize benefits while ensuring privacy of health information? And how can people and communities with different values and perspectives be maximally engaged in these important questions? Neuroethics: Anticipating the Future is written by scholars from diverse disciplines—neurology and neuroscience, ethics and law, public health, sociology, and philosophy. With its forward-looking insights and considerations for the future, the book examines the most pressing current ethical issues.

scholarly journals The path from trigeminal asymmetry to cognitive impairment: a behavioral and molecular study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maria Paola Tramonti Fantozzi ◽  
Giulia Lazzarini ◽  
Vincenzo De Cicco ◽  
Angela Briganti ◽  
Serena Argento ◽  
...  
Keyword(s):  
Pupil Size ◽  
Muscle Spindles ◽  
Molecular Study ◽  
Contralateral Side ◽  
Acute Effects ◽  
Adult Rats ◽  
Afferent Inputs ◽  
Acute And Chronic Effects ◽  
The Brain ◽  
Mandibular Branch

AbstractTrigeminal input exerts acute and chronic effects on the brain, modulating cognitive functions. Here, new data from humans and animals suggest that these effects are caused by trigeminal influences on the Locus Coeruleus (LC). In humans subjects clenching with masseter asymmetric activity, occlusal correction improved cognition, alongside with reductions in pupil size and anisocoria, proxies of LC activity and asymmetry, respectively. Notably, reductions in pupil size at rest on the hypertonic side predicted cognitive improvements. In adult rats, a distal unilateral section of the trigeminal mandibular branch reduced, on the contralateral side, the expression of c-Fos (brainstem) and BDNF (brainstem, hippocampus, frontal cortex). This counterintuitive finding can be explained by the following model: teeth contact perception loss on the lesioned side results in an increased occlusal effort, which enhances afferent inputs from muscle spindles and posterior periodontal receptors, spared by the distal lesion. Such effort leads to a reduced engagement of the intact side, with a corresponding reduction in the afferent inputs to the LC and in c-Fos and BDNF gene expression. In conclusion, acute effects of malocclusion on performance seem mediated by the LC, which could also contribute to the chronic trophic dysfunction induced by loss of trigeminal input.

Brain shift: an error factor during implantation of deep brain stimulation electrodes

2007 ◽  
Vol 107 (5) ◽  
pp. 989-997 ◽  
Author(s):  
Yasushi Miyagi ◽  
Fumio Shima ◽  
Tomio Sasaki
Keyword(s):  
Deep Brain Stimulation ◽  
Brain Stimulation ◽  
Brain Shift ◽  
Mr Images ◽  
Implanted Electrodes ◽  
Error Factor ◽  
Bilateral Surgery ◽  
Second Procedure ◽  
The Brain ◽  
Deep Brain

Object The goal of this study was to focus on the tendency of brain shift during stereotactic neurosurgery and the shift's impact on the unilateral and bilateral implantation of electrodes for deep brain stimulation (DBS). Methods Eight unilateral and 10 bilateral DBS electrodes at 10 nuclei ventrales intermedii and 18 subthalamic nuclei were implanted in patients at Kaizuka Hospital with the aid of magnetic resonance (MR) imaging–guided and microelectrode-guided methods. Brain shift was assessed as changes in the 3D coordinates of the anterior and posterior commissures (AC and PC) with MR images before and immediately after the implantation surgery. The positions of the implanted electrodes, based on the midcommissural point and AC–PC line, were measured both on x-ray films (virtual position) during surgery and the postoperative MR images (actual position) obtained on the 7th day postoperatively. Results Contralateral and posterior shift of the AC and PC were the characteristics of unilateral and bilateral procedures, respectively. The authors suggest the following. 1) The first unilateral procedure elicits a unilateral air invasion, resulting in a contralateral brain shift. 2) During the second procedure in the bilateral surgery, the contralateral shift is reset to the midline and, at the same time, the anteroposterior support by the contralateral hemisphere against gravity is lost due to a bilateral air invasion, resulting in a significant posterior (caudal) shift. Conclusions To note the tendency of the brain to shift is very important for accurate implantation of a DBS electrode or high frequency thermocoagulation, as well as for the prediction of therapeutic and adverse effects of stereotactic surgery.

scholarly journals Comparisons of neuroinflammation, microglial activation, and degeneration of the locus coeruleus-norepinephrine system in APP/PS1 and aging mice

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Song Cao ◽  
Daniel W. Fisher ◽  
Guadalupe Rodriguez ◽  
Tian Yu ◽  
Hongxin Dong
Keyword(s):  
Spinal Cord ◽  
Locus Coeruleus ◽  
Microglial Activation ◽  
Healthy Aging ◽  
Cell Types ◽  
Norepinephrine System ◽  
Protective Processes ◽  
The Central Nervous System ◽  
Brain And Spinal Cord ◽  
The Brain

Abstract Background The role of microglia in Alzheimer’s disease (AD) pathogenesis is becoming increasingly important, as activation of these cell types likely contributes to both pathological and protective processes associated with all phases of the disease. During early AD pathogenesis, one of the first areas of degeneration is the locus coeruleus (LC), which provides broad innervation of the central nervous system and facilitates norepinephrine (NE) transmission. Though the LC-NE is likely to influence microglial dynamics, it is unclear how these systems change with AD compared to otherwise healthy aging. Methods In this study, we evaluated the dynamic changes of neuroinflammation and neurodegeneration in the LC-NE system in the brain and spinal cord of APP/PS1 mice and aged WT mice using immunofluorescence and ELISA. Results Our results demonstrated increased expression of inflammatory cytokines and microglial activation observed in the cortex, hippocampus, and spinal cord of APP/PS1 compared to WT mice. LC-NE neuron and fiber loss as well as reduced norepinephrine transporter (NET) expression was more evident in APP/PS1 mice, although NE levels were similar between 12-month-old APP/PS1 and WT mice. Notably, the degree of microglial activation, LC-NE nerve fiber loss, and NET reduction in the brain and spinal cord were more severe in 12-month-old APP/PS1 compared to 12- and 24-month-old WT mice. Conclusion These results suggest that elevated neuroinflammation and microglial activation in the brain and spinal cord of APP/PS1 mice correlate with significant degeneration of the LC-NE system.

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