scholarly journals The Human Hippocampus Contributes to Egocentric Coding of Distance to a Local Landmark

2018 ◽  
Author(s):  
Xiaoli Chen ◽  
Paula Vieweg ◽  
Thomas Wolbers
Keyword(s):  
Optic Flow ◽  
Path Integration ◽  
Target Location ◽  
Morphological Variability ◽  
Hippocampal Volume ◽  
Walking Distance ◽  
Behavioral Variability ◽  
Healthy Humans ◽  
Anatomical Basis ◽  
Local Landmark

AbstractSpatial navigation can depend on path integration or environmental cues (e.g., landmarks), which are thought to be integrated in hippocampal and entorhinal circuits. This study investigates the anatomical basis of path integration and navigation based on a single local landmark using an individual differences approach, since people vary substantially in their ability to navigate with path integration cues and landmarks. In two experiments, we dissociated the use of path integration and a local landmark in the same navigation task, and investigated whether morphological variability in the hippocampus and entorhinal cortex could explain behavioral variability in young healthy humans. In Experiment 1, participants navigated in a fully immersive virtual reality environment, with body-based cues available for path integration. The participants first walked through a series of posts before attempting to walk back to the remembered location of the first post. We found that gray matter volume of the hippocampus positively predicted behavioral accuracy of retrieving the target’s distance in relation to the local landmark. Hippocampus also positively predicted path integration performance in terms of walking-distance to the target location. Experiment 2 was conducted in a desktop virtual environment, with no body-based cues available. Optic flow served as path integration cues, and participants were tested on their memory of a learned target location along a linear track. Consistent with Experiment 1, the results showed that hippocampal volume positively predicted performance on the target’s distance in relation to the local landmark. In contrast to Experiment 1, there was no correlation between hippocampal volume and path integration performance. Together, our two experiments provide novel and converging evidence that the hippocampus plays an important role in encoding egocentric distance to a single local landmark during navigation, and they suggest a stronger hippocampal involvement when path integration is based on body-based compared to optic flow cues.

Clinical and neurobiological effects of aerobic endurance training in multi-episode schizophrenia patients

2016 ◽  
Vol 33 (S1) ◽  
pp. S41-S41
Author(s):  
P. Falkai
Keyword(s):  
Aerobic Exercise ◽  
Neural Plasticity ◽  
Neural Progenitor Cells ◽  
Hippocampal Volume ◽  
Brain Disorder ◽  
Healthy Humans ◽  
Proliferation And Differentiation ◽  
Competing Interest ◽  
Related Proteins ◽  
The Brain

Schizophrenia is a severe brain disorder characterised by positive, negative, affective and cognitive symptoms and can be viewed as a disorder of impaired neural plasticity. Aerobic exercise has a profound impact on the plasticity of the brain of both rodents and humans such as inducing the proliferation and differentiation of neural progenitor cells of the hippocampus in mice and rats. Aerobic exercise enhances LTP and leads to a better performance in hippocampus related memory tasks, eventually by increasing metabolic and synaptic plasticity related proteins in the hippocampus. In healthy humans, regular aerobic exercise increases hippocampal volume and seems to diminish processes of ageing like brain atrophy and cognitive decline.Disclosure of interestThe author has not supplied his declaration of competing interest.

scholarly journals Self‐reported navigation ability is associated with optic flow‐sensitive regions’ functional connectivity patterns during visual path integration

2019 ◽  
Vol 9 (4) ◽  
pp. e01236 ◽  
Author(s):  
Lauren Zajac ◽  
Heather Burte ◽  
Holly A. Taylor ◽  
Ronald Killiany
Keyword(s):  
Functional Connectivity ◽  
Optic Flow ◽  
Path Integration ◽  
Connectivity Patterns

The BDNF Val66Met polymorphism impacts parahippocampal and amygdala volume in healthy humans: incremental support for a genetic risk factor for depression

2009 ◽  
Vol 39 (11) ◽  
pp. 1831-1839 ◽  
Author(s):  
C. Montag ◽  
B. Weber ◽  
K. Fliessbach ◽  
C. Elger ◽  
M. Reuter
Keyword(s):  
Risk Factor ◽  
Affective Disorders ◽  
Region Of Interest ◽  
Hippocampal Volume ◽  
Parahippocampal Gyrus ◽  
Structural Imaging ◽  
Val66met Polymorphism ◽  
Healthy Humans ◽  
Bdnf Val66met Polymorphism ◽  
The Impact

BackgroundThe role of the brain-derived neurotrophic factor (BDNF) in the pathogenesis of affective disorders such as depression has been controversial. Mounting evidence comes from structural imaging, that the functional BDNF Val66Met polymorphism influences the hippocampal volume with carriers of the 66Met allele (Val/Met and Met/Met group) having smaller hippocampi. Given that stress-induced atrophy of the hippocampus is associated with the pathogenesis of affective disorders, the functional BDNF Val66Met polymorphism could be an incremental risk factor.MethodEighty-seven healthy Caucasian participants underwent structural imaging and were genotyped for the BDNF Val66Met polymorphism. Data were analysed by means of voxel-based morphometry (VBM).ResultsRegion of interest (ROI) analyses revealed an association between the 66Met allele and smaller parahippocampal volumes and a smaller right amygdala. In addition, the whole-brain analysis showed that the thalamus, fusiformus gyrus and several parts of the frontal gyrus were smaller in 66Met allele carriers.ConclusionsThis study demonstrates that the impact of the BDNF Val66Met polymorphism is not confined to the hippocampus but also extends to the parahippocampal gyrus and the amygdala.

scholarly journals Dissociative Effects of Methylphenidate in Nonhuman Primates: Trade-offs between Cognitive and Behavioral Performance

2012 ◽  
Vol 24 (6) ◽  
pp. 1371-1381 ◽  
Author(s):  
Abigail Z. Rajala ◽  
Jeffrey B. Henriques ◽  
Luis C. Populin
Keyword(s):  
Working Memory ◽  
Target Location ◽  
Memory Performance ◽  
Memory Task ◽  
Delayed Response ◽  
Impaired Performance ◽  
Healthy Humans ◽  
Trade Offs ◽  
Accuracy And Precision ◽  
Response Task

Low doses of methylphenidate reduce hyperactivity and improve attention in individuals with attention deficit hyperactivity disorder (ADHD) as well as in healthy humans and animals. Despite its extensive use, relatively little is known about its mechanisms of action. This study investigated the effects of methylphenidate on working memory performance, impulsivity, response accuracy and precision, and the ability to stay on task in rhesus monkeys using an oculomotor delayed response task. Methylphenidate affected task performance in an inverted-U manner in all three subjects tested. The improvements resulted from a reduction in premature responses and, importantly, not from improvement in the memory of target location. The length of time subjects participated in each session was also affected dose dependently. However, the dose at which the length of participation was maximally increased significantly impaired performance on the working memory task. This dissociation of effects has implications for the treatment of ADHD, for the nonprescription use of methylphenidate for cognitive enhancement, and for furthering the basic understanding of the neural substrate underlying these processes.

Human Path Integration by Optic Flow

2004 ◽  
Vol 4 (3) ◽  
pp. 255-272 ◽  
Author(s):  
Timothy M. Ellmore ◽  
Bruce L. McNaughton
Keyword(s):  
Optic Flow ◽  
Path Integration

scholarly journals A Dynamic Bayesian Observer Model Reveals Origins of Bias in Visual Path Integration

2017 ◽  
Author(s):  
Kaushik J Lakshminarasimhan ◽  
Marina Petsalis ◽  
Hyeshin Park ◽  
Gregory C DeAngelis ◽  
Xaq Pitkow ◽  
...  
Keyword(s):  
Optic Flow ◽  
Path Integration ◽  
Human Subjects ◽  
Signal Integration ◽  
Motion Velocity ◽  
Navigation Strategy ◽  
Prior Expectation ◽  
Leaky Integration ◽  
Observer Model ◽  
Self Motion

ABSTRACTPath integration is a navigation strategy by which animals track their position by integrating their self-motion velocity over time. To identify the computational origins of bias in visual path integration, we asked human subjects to navigate in a virtual environment using optic flow, and found that they generally travelled beyond the goal location. Such a behaviour could stem from leaky integration of unbiased self-motion velocity estimates, or from a prior expectation favouring slower speeds that causes underestimation of velocity. We tested both alternatives using a probabilistic framework that maximizes expected reward, and found that subjects’ biases were better explained by a slow-speed prior than imperfect integration. When subjects integrate paths over long periods, this framework intriguingly predicts a distance-dependent bias reversal due to build-up of uncertainty, which we also confirmed experimentally. These results suggest that visual path integration performance is limited largely by biases in processing optic flow rather than by suboptimal signal integration.

scholarly journals Visual Homing Is Possible Without Landmarks: A Path Integration Study in Virtual Reality

2002 ◽  
Vol 11 (5) ◽  
pp. 443-473 ◽  
Author(s):  
Bernhard E. Riecke ◽  
Henricus A. H. C. van Veen ◽  
Heinrich H. Bülthoff
Keyword(s):  
Optic Flow ◽  
Path Integration ◽  
Visual Cues ◽  
Movement Velocity ◽  
Ability Test ◽  
Projection Screen ◽  
Flow Information ◽  
Homing Performance ◽  
Set Up ◽  
Triangle Completion

The literature often suggests that proprioceptive and especially vestibular cues are required for navigation and spatial orientation tasks involving rotations of the observer. To test this notion, we conducted a set of experiments in virtual environments in which only visual cues were provided. Participants had to execute turns, reproduce distances, or perform triangle completion tasks. Most experiments were performed in a simulated 3D field of blobs, thus restricting navigation strategies to path integration based on optic flow. For our experimental set-up (half-cylindrical 180 deg. projection screen), optic flow information alone proved to be sufficient for untrained participants to perform turns and reproduce distances with negligible systematic errors, irrespective of movement velocity. Path integration by optic flow was sufficient for homing by triangle completion, but homing distances were biased towards the mean response. Additional landmarks that were only temporarily available did not improve homing performance. However, navigation by stable, reliable landmarks led to almost perfect homing performance. Mental spatial ability test scores correlated positively with homing performance, especially for the more complex triangle completion tasks—suggesting that mental spatial abilities might be a determining factor for navigation performance. In summary, visual path integration without any vestibular or kinesthetic cues can be sufficient for elementary navigation tasks like rotations, translations, and triangle completion.

scholarly journals Path Integration from Optic Flow and Body Senses in a Homing Task

Perception ◽  
10.1068/p3311 ◽  
2002 ◽  
Vol 31 (3) ◽  
pp. 349-374 ◽  
Author(s):  
Melissa J Kearns ◽  
William H Warren ◽  
Andrew P Duchon ◽  
Michael J Tarr
Keyword(s):  
Virtual Environment ◽  
Optic Flow ◽  
Path Integration ◽  
Proprioceptive Information ◽  
Completion Task ◽  
Triangle Completion ◽  
Joystick Control

We examined the roles of information from optic flow and body senses (eg vestibular and proprioceptive information) for path integration, using a triangle completion task in a virtual environment. In two experiments, the contribution of optic flow was isolated by using a joystick control. Five circular arenas were used for testing: (B) both floor and wall texture; (F) floor texture only, reducing information for rotation; (W) wall texture only, reducing information for translation; (N) a no texture control condition; and (P) an array of posts. The results indicate that humans can use optic flow for path integration and are differentially influenced by rotational and translational flow. In a third experiment, participants actively walked in arenas B, F, and N, so body senses were also available. Performance shifted from a pattern of underturning to overturning and exhibited decreased variability, similar responses with and without optic flow, and no attrition. The results indicate that path integration can be performed by integrating optic flow, but when information from body senses is available it appears to dominate.

scholarly journals Influence of sensory modality and control dynamics on human path integration

2020 ◽  
Author(s):  
Akis Stavropoulos ◽  
Kaushik J. Lakshminarasimhan ◽  
Jean Laurens ◽  
Xaq Pitkow ◽  
Dora E. Angelaki
Keyword(s):  
Virtual Reality ◽  
Path Integration ◽  
Internal Model ◽  
Target Location ◽  
Sensory Modality ◽  
Sensory Pathways ◽  
Movement Dynamics ◽  
Highly Sensitive ◽  
Motion Cueing ◽  
And Control

AbstractPath integration is a widely-studied sensorimotor computation to infer latent dynamical states. How different sensory pathways and movement dynamics constrain this computation is unclear. We studied the influence of sensory observation (visual/vestibular) and latent control dynamics (velocity/acceleration) on human path integration using a novel motion-cueing algorithm. Sensory modality and control dynamics were both varied randomly across trials, as participants controlled a joystick to steer to a memorized target location in virtual reality. Visual and vestibular steering cues allowed comparable accuracies only when participants controlled their acceleration, suggesting that vestibular signals, on their own, fail to support accurate path integration in the absence of sustained acceleration. Nevertheless, performance in all conditions was highly sensitive to the underlying control dynamics, a result that was well explained by a bias in the dynamics estimation. This work demonstrates that people need an accurate internal model of control dynamics when navigating in volatile environments.

scholarly journals Path Integration: Combining Optic Flow with Compass Orientation

2017 ◽  
Vol 27 (20) ◽  
pp. R1113-R1116 ◽  
Author(s):  
Matthew Collett ◽  
Thomas S. Collett
Keyword(s):  
Optic Flow ◽  
Path Integration ◽  
Compass Orientation
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