scholarly journals Experience-dependent effects of muscimol-induced hippocampal excitation on mnemonic discrimination

2018 ◽  
Author(s):  
Sarah A. Johnson ◽  
Sean M. Turner ◽  
Katelyn N. Lubke ◽  
Tara L. Cooper ◽  
Kaeli E. Fertal ◽  
...  
Keyword(s):  
Neural Activity ◽  
Test Block ◽  
Behavioral Experiments ◽  
Stimulus Similarity ◽  
Impact Performance ◽  
Subsequent Test ◽  
Hippocampal Activity ◽  
Hippocampal Ca3 ◽  
Within Subjects ◽  
Clinical Conditions

AbstractMemory requires similar episodes with overlapping features to be represented distinctly, a process that is disrupted in many clinical conditions as well as normal aging. Data from humans have linked this ability to activity in hippocampal CA3 and dentate gyrus (DG). While animal models have shown the perirhinal cortex is critical for disambiguating similar stimuli, hippocampal activity has not been causally linked to discrimination abilities. The goal of the current study was to determine how disrupting CA3/DG activity would impact performance on a rodent mnemonic discrimination task. Rats were surgically implanted with bilateral guide cannulae targeting dorsal CA3/DG. In Exp.1, the effect of intra-hippocampal muscimol on target-lure discrimination was assessed within subjects in randomized blocks. Muscimol initially impaired discrimination across all levels of target-lure similarity, but performance improved on subsequent test blocks irrespective of stimulus similarity and infusion condition. To clarify these results, Exp.2 examined whether prior experience with objects influenced the effect of muscimol on target-lure discrimination. Rats that received vehicle infusions in a first test block, followed by muscimol in a second block, did not show discrimination impairments for target-lure pairs of any similarity. In contrast, rats that received muscimol infusions in the first test block were impaired across all levels of target-lure similarity. Sustained effects of muscimol in disrupting behavioral performance after repeated infusions were verified in a spatial alternation task. At the conclusion of behavioral experiments, fluorescence in situ hybridization for the immediate-early genes Arc and Homer1a was used to determine the proportion of neurons active following muscimol infusion. Contrary to expectations, muscimol increased neural activity in DG. An additional experiment was carried out to quantify neural activity in naïve rats that received an intra-hippocampal infusion of vehicle or muscimol. Results confirmed that muscimol led to DG excitation, likely through its actions on interneuron populations in hilar and molecular layers of DG and consequent disinhibition of principal cells. Taken together, our results suggest disruption of coordinated neural activity across the hippocampus impairs mnemonic discrimination when lure stimuli are novel.

scholarly journals Serotonin buffers hippocampal neuroplasticity and emotional behavior

2017 ◽  
Author(s):  
Giacomo Maddaloni ◽  
Sara Migliarini ◽  
Francesco Napolitano ◽  
Andrea Giorgi ◽  
Daniele Biasci ◽  
...  
Keyword(s):  
Emotional Behavior ◽  
Adaptive Responses ◽  
Behavioral Experiments ◽  
Behavioral Traits ◽  
Hippocampal Activity ◽  
Adaptive Mechanisms ◽  
Core Symptoms ◽  
The Impact

Adaptation to environmental insults is an evolutionary mechanism essential for survival. The hippocampus participates in controlling adaptive responses to stress and emotional state through the modulation of neuroplasticity events, which are dysregulated in stress-related neuropsychiatric disorders. The neurotransmitter serotonin (5-HT) has been proposed as a pivotal player in hippocampal neuroplasticity in both normal and neuropsychiatric conditions though its role remains still poorly understood. Here, we investigated the impact of 5-HT deficiency on hippocampal activity combining RNA-seq, in vivo neuroimaging, neuroanatomical, biochemical and behavioral experiments on 5-HT depleted mice. We unveil that serotonin is required for appropriate activation of neuroplasticity adaptive mechanisms to environmental insults. Bidirectional deregulation of these programs in serotonin depleted mice is associated with opposite behavioral traits that model core symptoms of bipolar disorder. These findings delineate a previously unreported buffering role of 5-HT in instructing hippocampal activity and emotional responses to environmental demands.

scholarly journals Revisiting the Neural Architecture of Decision-Making: Univariate and Multivariate Evidence for System-Based Models in Adolescence

2020 ◽  
Author(s):  
João F. Guassi Moreira ◽  
Adriana S. Méndez Leal ◽  
Yael H. Waizman ◽  
Natalie Saragosa-Harris ◽  
Emilia Ninova ◽  
...  
Keyword(s):  
Decision Making ◽  
Cognitive Control ◽  
Risk Taking ◽  
Neural Activity ◽  
Brain Activity ◽  
Empirical Support ◽  
Risky Decision ◽  
Human Decision ◽  
Within Subjects ◽  
Multivariate Pattern

AbstractSystem-based theories are a popular approach to explaining the psychology of human decision making. Such theories posit that decision-making is governed by interactions between different psychological processes that arbitrate amongst each other for control over behavior. To date, system-based theories have received inconsistent support at the neural level, leading some to question their veracity. Here we examine the possibility that prior attempts to evaluate system-based theories have been limited by their reliance on predicting brain activity from behavior, and seek to advance evaluations of system-based models through modeling approaches that predict behavior from brain activity. Using within-subject decision-level modeling of fMRI data from a risk-taking task in a sample of over 2000 decisions across 51 adolescents—a population in which decision-making processes are particularly dynamic and consequential—we find support for system-based theories of decision-making. In particular, neural activity in lateral prefrontal cortex and a multivariate pattern of cognitive control both predicted a reduced likelihood of making a risky decision, whereas increased activity in the ventral striatum—a region typically associated with valuation processes—predicted a greater likelihood of engaging in risk-taking. These results comprise the first formalized within-subjects neuroimaging test of system-based theories, garnering support for the notion that competing systems drive decision behaviors.Significance StatementDecision making is central to adaptive behavior. While dominant psychological theories of decision-making behavior have found empirical support, their neuroscientific implementations have received inconsistent support. This may in part be due to statistical approaches employed by prior neuroimaging studies of system-based theories. Here we use brain modeling—an approach that predicts behavior from brain activity—of univariate and multivariate neural activity metrics to better understand how neural components of psychological systems guide decision behavior. We found broad support for system-based theories such that that neural systems involved in cognitive control predicted a reduced likelihood to make risky decisions, whereas value-based systems predicted greater risk-taking propensity.

scholarly journals Evidence for immediate enhancement of hippocampal memory encoding by network-targeted theta-burst stimulation during concurrent fMRI

2020 ◽  
Author(s):  
Molly S. Hermiller ◽  
Yu Fen Chen ◽  
Todd B. Parrish ◽  
Joel L. Voss
Keyword(s):  
Episodic Memory ◽  
Neural Activity ◽  
Theta Band ◽  
Theta Burst Stimulation ◽  
Burst Stimulation ◽  
Related Activity ◽  
Memory Processing ◽  
Hippocampal Activity ◽  
Hippocampal Network ◽  
Theta Burst

AbstractThe hippocampus supports episodic memory via interaction with a distributed brain network. Previous experiments using network-targeted noninvasive brain stimulation have identified episodic memory enhancements and modulation of activity within the hippocampal network. However, mechanistic insights were limited because these effects were measured long after stimulation and therefore could have reflected various neuroplastic aftereffects with extended timecourses. In this experiment with human subjects of both sexes, we tested for immediate stimulation impact on encoding-related activity of the hippocampus and immediately adjacent medial-temporal cortex by delivering theta-burst transcranial magnetic stimulation (TBS) concurrent with fMRI, as an immediate impact of stimulation would suggest an influence on neural activity. We reasoned that TBS would be particularly effective for influencing the hippocampus because rhythmic neural activity in the theta band is associated with hippocampal memory processing. First, we demonstrated that it is possible to obtain robust fMRI correlates of task-related activity during concurrent TBS. We then identified immediate effects of TBS on encoding of visual scenes. Brief volleys of TBS targeting the hippocampal network increased activity of the targeted (left) hippocampus during scene encoding and increased subsequent recollection. Stimulation did not influence activity during an intermixed numerical task with no memory demand. Control conditions using beta-band and out-of-network stimulation also did not influence hippocampal activity or recollection. TBS targeting the hippocampal network therefore immediately impacted hippocampal memory processing. This suggests direct, beneficial influence of stimulation on hippocampal neural activity related to memory and supports the role of theta-band activity in human episodic memory.Significance StatementCan noninvasive stimulation directly impact function of indirect, deep-brain targets such as the hippocampus? We tested this by targeting an accessible region of the hippocampal network via transcranial magnetic stimulation during concurrent fMRI. We reasoned that theta-burst stimulation would be particularly effective for impacting hippocampal function, as this stimulation rhythm should resonate with the endogenous theta-nested-gamma activity prominent in hippocampus. Indeed, theta-burst stimulation targeting the hippocampal network immediately impacted hippocampal activity during encoding, improving memory formation as indicated by enhanced later recollection. Rhythm- and location-control stimulation conditions had no such effects. These findings suggest a direct influence of noninvasive stimulation on hippocampal neural activity and highlight that the theta-burst rhythm is relatively privileged in its ability to influence hippocampal memory function.

scholarly journals Restricting visual exploration directly impedes neural activity, functional connectivity, and memory

2020 ◽  
Author(s):  
Zhong-Xu Liu ◽  
R. Shayna Rosenbaum ◽  
Jennifer D. Ryan
Keyword(s):  
Functional Connectivity ◽  
Neural Activity ◽  
Visual Exploration ◽  
Basic Unit ◽  
Visual Stream ◽  
Memory Binding ◽  
Single Location ◽  
Hippocampal Activity ◽  
Cortical Regions ◽  
Gaze Fixations

AbstractWe 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 relationships between gaze fixations, neural activity, and memory during scene viewing. Compared to free viewing, fixating a single location reduced: 1) subsequent memory, 2) neural activity along the ventral visual stream into the hippocampus, 3) neural similarity between effects of subsequent memory and visual exploration, and 4) functional connectivity among the hippocampus, parahippocampal place area, and other cortical regions. Gaze fixations were uniquely related to hippocampal activity, even after controlling for neural effects due to subsequent memory. Individual gaze fixations may provide the basic unit of information on which memory binding processes operate.

scholarly journals Optogenetic olfactory behavior depends on illumination characteristics

2019 ◽  
Author(s):  
Tayfun Tumkaya ◽  
James Stewart ◽  
Safwan B. Burhanudin ◽  
Adam Claridge-Chang
Keyword(s):  
Neural Activity ◽  
Olfactory Receptor ◽  
Olfactory Receptor Neurons ◽  
Olfactory Behavior ◽  
Pulsed Light ◽  
Behavioral Experiments ◽  
Light Intensities ◽  
Light Stimuli ◽  
Receptor Neurons ◽  
Illumination Regime

AbstractOptogenetics has become an important tool for the study of behavior, enabling neuroscientists to infer causations by examining behavior after activating genetically circumscribed neurons with light. Light-induced neural activity is affected by illumination parameters used in experiments, such as intensity, duration, and frequency. Here, we hypothesized that the intensity of light and the presence of oscillations in illumination would alter optogenetically induced olfactory behaviours. To test this, we activated olfactory receptor neurons (ORNs) in Drosophila by using either static or pulsed light stimuli across a range of light intensities. The various regimes elicited distinct behavioral valence responses (attraction, aversion, indifference) from several ORN types. Our results demonstrate the importance of both frequency and intensity for interpreting optogenetic behavioral experiments accurately; successfully generalizing optogenetic results requires the use of more than a single illumination regime.

scholarly journals Chronic Treatment with Squid Phosphatidylserine Activates Glucose Uptake and Ameliorates TMT-Induced Cognitive Deficit in Rats via Activation of Cholinergic Systems

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Hyun-Jung Park ◽  
Seung Youn Lee ◽  
Hyun Soo Shim ◽  
Jin Su Kim ◽  
Kyung Soo Kim ◽  
...  
Keyword(s):  
Passive Avoidance ◽  
Glucose Uptake ◽  
Neural Activity ◽  
Cognitive Deficit ◽  
Memory Function ◽  
Control Group ◽  
Avoidance Task ◽  
Positron Emission ◽  
Hippocampal Ca1 ◽  
Hippocampal Ca3

The present study examined the effects of squid phosphatidylserine (Squid-PS) on the learning and memory function and the neural activity in rats with TMT-induced memory deficits. The rats were administered saline or squid derived Squid-PS (Squid-PS 50 mg kg−1,p.o.) daily for 21 days. The cognitive improving efficacy of Squid-PS on the amnesic rats, which was induced by TMT, was investigated by assessing the passive avoidance task and by performing choline acetyltransferase (ChAT) and acetylcholinesterase (AchE) immunohistochemistry. 18F-Fluorodeoxyglucose and performed a positron emission tomography (PET) scan was also performed. In the passive avoidance test, the control group which were injected with TMT showed a markedly lower latency time than the non-treated normal group (P<0.05). However, treatment of Squid-PS significantly recovered the impairment of memory compared to the control group (P<0.05). Consistent with the behavioral data, Squid-PS significantly alleviated the loss of ChAT immunoreactive neurons in the hippocampal CA3 compared to that of the control group (P<0.01). Also, Squid-PS significantly increased the AchE positive neurons in the hippocampal CA1 and CA3. In the PET analysis, Squid-PS treatment increased the glucose uptake more than twofold in the frontal lobe and the hippocampus (P<0.05, resp.). These results suggest that Squid-PS may be useful for improving the cognitive function via regulation of cholinergic enzyme activity and neural activity.

scholarly journals Testing, Testing, 1 2 3: Exploring the Mitigating Effects of Sound on Test Performance

2018 ◽  
Author(s):  
Phoebe Viola Sartori Amsberry
Keyword(s):  
Standardized Testing ◽  
Test Anxiety ◽  
Test Performance ◽  
Cognitive Factors ◽  
Improve Performance ◽  
Testing Environment ◽  
Impact Performance ◽  
Within Subjects ◽  
The Individual ◽  
Study Participants

Due to the amount of pressure put on students to perform well and the growing amount of standardized testing in the American Education system, there has been a dramatic increase in the identification and study of test anxiety and its impact on performance. Treatments of test anxiety are typically preventative in nature and focus on what can be done outside of the classroom on the part of the individual to improve performance. However, it may be more impactful to manipulate the actual testing environment on a larger scale. This study, through a 4 week within-subjects model, sought to explore these environmental manipulations through the inclusion of sound in the environment. Throughout this study participants were subjected to testing in silence, preferred, nonpreferred, and ambient soundscapes. Test performance was significantly improved (by up to 22%) when participants were exposed to preferred music stimuli. However, performance is a complex phenomenon impacted by many different variables and more research should be done exploring how different cognitive factors impact performance.

scholarly journals Restricting Visual Exploration Directly Impedes Neural Activity, Functional Connectivity, and Memory

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Zhong-Xu Liu ◽  
R Shayna Rosenbaum ◽  
Jennifer D Ryan
Keyword(s):  
Functional Connectivity ◽  
Neural Activity ◽  
Memory Systems ◽  
Visual Exploration ◽  
Basic Unit ◽  
Visual Stream ◽  
Single Location ◽  
Hippocampal Activity ◽  
Cortical Regions ◽  
Gaze Fixations

Abstract 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 relationships between gaze fixations, neural activity, and memory during scene viewing. Compared to free viewing, fixating a single location reduced: 1) subsequent memory, 2) neural activity along the ventral visual stream into the hippocampus, 3) neural similarity between effects of subsequent memory and visual exploration, and 4) functional connectivity among the hippocampus, parahippocampal place area, and other cortical regions. Gaze fixations were uniquely related to hippocampal activity, even after controlling for neural effects due to subsequent memory. Therefore, this study provides key causal evidence supporting the notion that the oculomotor and memory systems are intrinsically related at both the behavioral and neural level. Individual gaze fixations may provide the basic unit of information on which memory binding processes operate.

scholarly journals Neural activity in a hippocampus-like region of the teleost pallium is associated with active sensing and navigation

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Haleh Fotowat ◽  
Candice Lee ◽  
James Jaeyoon Jun ◽  
Len Maler
Keyword(s):  
Neural Activity ◽  
Electric Organ Discharge ◽  
Discharge Rate ◽  
Electric Organ ◽  
Weakly Electric Fish ◽  
Active Sensing ◽  
Head Region ◽  
Hippocampal Ca3 ◽  
And Control ◽  
Weakly Electric

Most vertebrates use active sensing strategies for perception, cognition and control of motor activity. These strategies include directed body/sensor movements or increases in discrete sensory sampling events. The weakly electric fish, Gymnotus sp., uses its active electric sense during navigation in the dark. Electric organ discharge rate undergoes transient increases during navigation to increase electrosensory sampling. Gymnotus also use stereotyped backward swimming as an important form of active sensing that brings objects toward the electroreceptor dense fovea-like head region. We wirelessly recorded neural activity from the pallium of freely swimming Gymnotus. Spiking activity was sparse and occurred only during swimming. Notably, most units tended to fire during backward swims and their activity was on average coupled to increases in sensory sampling. Our results provide the first characterization of neural activity in a hippocampal (CA3)-like region of a teleost fish brain and connects it to active sensing of spatial environmental features.

scholarly journals Wandering minds, sleepy brains: lapses of attention and local sleep in wakefulness

2020 ◽  
Author(s):  
Thomas Andrillon ◽  
Angus Burns ◽  
Teigane MacKay ◽  
Jennifer Windt ◽  
Naotsugu Tsuchiya
Keyword(s):  
Neural Activity ◽  
Subjective Experience ◽  
Mind Wandering ◽  
Mental States ◽  
Cognitive Profiles ◽  
Stream Of Consciousness ◽  
Impact Performance ◽  
Attentional Lapses ◽  
The Mind ◽  
Local Sleep

AbstractAttentional lapses are ubiquitous and can negatively impact performance. They correlate with mind wandering, or thoughts that are unrelated to ongoing tasks and environmental demands. In other cases, the stream of consciousness itself comes to a halt and the mind goes blank. What happens in the brain that leads to these mental states? To understand the neural mechanisms underlying attentional lapses, we cross-analyzed the behavior, subjective experience and neural activity of healthy participants performing a task. Random interruptions prompted participants to indicate whether they were task-focused, mind-wandering or mind-blanking. High-density electroencephalography revealed the occurrence of spatially and temporally localized sleep-like patterns of neural activity. This “local sleep” accompanied behavioral markers of lapses and preceded reports of mind wandering and mind blanking. Furthermore, the location of local sleep distinguished sluggish versus impulsive behaviors, mind wandering versus mind blanking. Despite contrasting cognitive profiles, attentional lapses could share a common physiological origin: the appearance of local islets of sleep within the awake brain.

Sign in / Sign up

Export Citation Format

Share Document