scholarly journals Neural representations of space in the hippocampus of a food-caching bird

Science ◽  
2021 ◽  
Vol 373 (6552) ◽  
pp. 343-348
Author(s):  
H. L. Payne ◽  
G. F. Lynch ◽  
D. Aronov
Keyword(s):  
Spatial Memory ◽  
Neural Activity ◽  
Strong Dependence ◽  
Bird Species ◽  
Brain Regions ◽  
Food Caching ◽  
Neural Representations ◽  
Hippocampal Activity ◽  
Species Specific ◽  
Representations Of Space

Spatial memory in vertebrates requires brain regions homologous to the mammalian hippocampus. Between vertebrate clades, however, these regions are anatomically distinct and appear to produce different spatial patterns of neural activity. We asked whether hippocampal activity is fundamentally different even between distant vertebrates that share a strong dependence on spatial memory. We studied tufted titmice, food-caching birds capable of remembering many concealed food locations. We found mammalian-like neural activity in the titmouse hippocampus, including sharp-wave ripples and anatomically organized place cells. In a non–food-caching bird species, spatial firing was less informative and was exhibited by fewer neurons. These findings suggest that hippocampal circuit mechanisms are similar between birds and mammals, but that the resulting patterns of activity may vary quantitatively with species-specific ethological needs.

scholarly journals Age-related declines in neural distinctiveness correlate across brain areas and result from both decreased reliability and increased confusability

2021 ◽  
Author(s):  
Molly Simmonite ◽  
Thad A Polk
Keyword(s):  
Neural Activity ◽  
Healthy Aging ◽  
Brain Regions ◽  
Aging Brain ◽  
Activation Patterns ◽  
Neural Representations ◽  
Age Related ◽  
Behavioural Performance ◽  
The Difference ◽  
The Brain

According to the neural dedifferentiation hypothesis, age-related reductions in the distinctiveness of neural representations contribute to sensory, cognitive, and motor declines associated with aging: neural activity associated with different stimulus categories becomes more confusable with age and behavioural performance suffers as a result. Initial studies investigated age-related dedifferentiation in the visual cortex, but subsequent research has revealed declines in other brain regions, suggesting that dedifferentiation may be a general feature of the aging brain. In the present study, we used functional magnetic resonance imaging to investigate age-related dedifferentiation in the visual, auditory, and motor cortices. Participants were 58 young adults and 79 older adults. The similarity of activation patterns across different blocks of the same condition was calculated (within-condition correlation, a measure of reliability) as was the similarity of activation patterns elicited by different conditions (between-category correlations, a measure of confusability). Neural distinctiveness was defined as the difference between the mean within- and between-condition similarity. We found age-related reductions in neural distinctiveness in the visual, auditory, and motor cortices, which were driven by both decreases in within-category similarity and increases in between-category similarity. There were significant positive cross-region correlations between neural distinctiveness in different regions. These correlations were driven by within-category similarities, a finding that indicates that declines in the reliability of neural activity appear to occur in tandem across the brain. These findings suggest that the changes in neural distinctiveness that occur in healthy aging result from changes in both the reliability and confusability of patterns of neural activity.

scholarly journals Variation in hippocampal morphology along an environmental gradient: controlling for the effects of day length

2011 ◽  
Vol 278 (1718) ◽  
pp. 2662-2667 ◽  
Author(s):  
Timothy C. Roth ◽  
Lara D. LaDage ◽  
Vladimir V. Pravosudov
Keyword(s):  
Spatial Memory ◽  
Snow Cover ◽  
Cognitive Abilities ◽  
Memory Function ◽  
Geographical Area ◽  
Brain Regions ◽  
Day Length ◽  
Relative Role ◽  
Food Caching ◽  
Significant Difference

Environmental conditions may create increased demands for memory, which in turn may affect specific brain regions responsible for memory function. This may occur either via phenotypic plasticity or selection for individuals with enhanced cognitive abilities. For food-caching animals, in particular, spatial memory appears to be important because it may have a direct effect on fitness via their ability to accurately retrieve food caches. Our previous studies have shown that caching animals living in more harsh environments (characterized by low temperatures, high snow cover and short day lengths) possess more neurons within a larger hippocampus (Hp), a part of the brain involved in spatial memory. However, the relative role of each of these environmental features in the relationship is unknown. Here, we dissociate the effects of one theoretically important factor (day length) within the environmental severity/Hp relationship by examining food-caching birds (black-capped chickadee, Poecile atricapillus ) selected at locations along the same latitude, but with very different climatic regimes. There was a significant difference in Hp attributes among populations along the same latitude with very different climatic features. Birds from the climatically mild location had significantly smaller Hp volumes and fewer Hp neurons than birds from the more harsh populations, even though all populations experienced similar day lengths. These results suggest that variables such as temperature and snow cover seem to be important even without the compounding effect of reduced day length at higher latitudes and suggest that low temperature and snow cover alone may be sufficient to generate high demands for memory and the hippocampus. Our data further confirmed that the association between harsh environment and the hippocampus in food-caching animals is robust across a large geographical area and across years.

scholarly journals Analogue representation of a spatial memory by ramp-like neural activity in retrohippocampal cortex

2021 ◽  
Author(s):  
Sarah A. Tennant ◽  
Ian Hawes ◽  
Harry Clark ◽  
Wing Kin Tam ◽  
Junji Hua ◽  
...  
Keyword(s):  
Spatial Memory ◽  
Firing Rate ◽  
Virtual Environment ◽  
Neural Activity ◽  
Path Integration ◽  
Track Structure ◽  
Firing Patterns ◽  
Sensory Signals ◽  
Neural Representations ◽  
Critical Location

AbstractWhen solving navigational problems, remembering that a critical location is approaching can enable appropriate behavioural choices without waiting for sensory signals. Whereas multiple types of neuron in the hippocampus and retrohippocampal cortex represent locations using codes based on discrete spatial firing fields, analogue neural representations may be advantageous for efficiently recalling proximity to locations of behavioral importance. Here, we identify retrohippocampal neurons that use analogue ramp-like changes in firing rate to represent location as mice navigate a virtual environment in which they have learned the location of a reward. Ramp-like firing patterns had positive or negative slopes and could switch polarity or reset their rate at the reward location. These transitions were maintained when location cues were removed, indicating that path integration is sufficient to drive recall of the track structure expressed through ramp-like codes. We suggest that analogue ramp-like representations encode learned models for goal-directed navigation.

scholarly journals Hippocampal volumes and neuron numbers increase along a gradient of environmental harshness: a large-scale comparison

2008 ◽  
Vol 276 (1656) ◽  
pp. 401-405 ◽  
Author(s):  
Timothy C Roth ◽  
Vladimir V Pravosudov
Keyword(s):  
Spatial Memory ◽  
Large Scale ◽  
Memory Function ◽  
Brain Regions ◽  
Climatic Conditions ◽  
Day Length ◽  
Harsh Environments ◽  
Environmental Pressures ◽  
Food Caching ◽  
Climatic Severity

Environmental conditions may provide specific demands for memory, which in turn may affect specific brain regions responsible for memory function. For food-caching animals, in particular, spatial memory appears to be important because it may have a direct effect on fitness via the accuracy of cache retrieval. Animals living in more harsh environments should rely more on cached food, and thus theoretically should have better memory to support cache retrieval, which may be crucial for survival. Consequently, animals in harsh environments may benefit from more neurons within a larger hippocampus (Hp), a part of the brain involved in spatial memory. Here, we present the first large-scale test of the hypothesis that Hp structure is related to the severity of the environment within a single food-caching species (the black-capped chickadee, Poecile atricapillus ) with a large range encompassing a great diversity of climatic conditions. Hp size in birds collected at five locations along a gradient of environmental harshness from Alaska to Kansas ranked perfectly with climatic severity. Birds from more harsh northern climates (defined by lower ambient temperature, shorter day length and more snow cover) had significantly larger Hp volumes and more Hp neurons (both relative to telencephalon volume) than those from more mild southern latitudes. Environmental pressures therefore seem capable of influencing specific brain regions independently, which may result in enhanced memory, and hence survival, in harsh climates.

scholarly journals Functional Near-Infrared Spectroscopy Neurofeedback Enhances Human Spatial Memory

2021 ◽  
Vol 15 ◽  
Author(s):  
Xin Hou ◽  
Xiang Xiao ◽  
Yilong Gong ◽  
Zheng Li ◽  
Antao Chen ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Spatial Memory ◽  
Near Infrared Spectroscopy ◽  
Neural Activity ◽  
Near Infrared ◽  
Brain Regions ◽  
Control Group ◽  
Cortical Region ◽  
Neural Activation ◽  
Functional Near Infrared Spectroscopy

Spatial memory is an important cognitive function for human daily life and may present dysfunction or decline due to aging or clinical diseases. Functional near-infrared spectroscopy neurofeedback (fNIRS-NFB) is a promising neuromodulation technique with several special advantages that can be used to improve human cognitive functions by manipulating the neural activity of targeted brain regions or networks. In this pilot study, we intended to test the feasibility of fNIRS-NFB to enhance human spatial memory ability. The lateral parietal cortex, an accessible cortical region in the posterior medial hippocampal-cortical network that plays a crucial role in human spatial memory processing, was selected as the potential feedback target. A placebo-controlled fNIRS-NFB experiment was conducted to instruct individuals to regulate the neural activity in this region or an irrelevant control region. Experimental results showed that individuals learned to up-regulate the neural activity in the region of interest successfully. A significant increase in spatial memory performance was found after 8-session neurofeedback training in the experimental group but not in the control group. Furthermore, neurofeedback-induced neural activation increase correlated with spatial memory improvement. In summary, this study preliminarily demonstrated the feasibility of fNIRS-NFB to improve human spatial memory and has important implications for further applications.

scholarly journals Precise spatial representations in the hippocampus of a food‑caching bird

2020 ◽  
Author(s):  
Hannah L. Payne ◽  
Galen F. Lynch ◽  
Dmitriy Aronov
Keyword(s):  
Neural Activity ◽  
Neural Circuit ◽  
Bird Species ◽  
Place Cells ◽  
Spatial Representations ◽  
Spatial Coding ◽  
Sharp Wave ◽  
Food Caching ◽  
Wide Range ◽  
Tufted Titmouse

SummaryThe hippocampus is an ancient neural circuit required for the formation of episodic memories. In mammals, this ability is thought to depend on well-documented patterns of neural activity, including place cells and sharp wave ripples. Notably, neither pattern has been found in non-mammals, despite compelling examples of episodic-like memory across a wide range of vertebrates. Does episodic memory nonetheless have a universal implementation across distant neural systems? We addressed this question by recording neural activity in the hippocampus of the tufted titmouse – an intense memory specialist from a food-caching family of birds. These birds cache large numbers of food items at scattered, concealed locations and use hippocampus-dependent memory to retrieve their caches. We found remarkably precise spatial representations akin to classic place cells, as well as sharp wave ripples, in the titmouse hippocampus. These patterns were organized along similar anatomical axes to those found in mammals. In contrast, spatial coding was weaker in a different, non-food-caching bird species. Our findings suggest a striking conservation of hippocampal mechanisms across distant vertebrates, in spite of vastly divergent anatomy and cytoarchitecture. At the same time, these results demonstrate that the exact implementation of such common mechanisms may conform to the unique ethological needs of different species.

Stable neural representations of mental states across target people and stimulus modalities

2020 ◽  
Author(s):  
Miriam E. Weaverdyck ◽  
Mark Allen Thornton ◽  
Diana Tamir
Keyword(s):  
Mental State ◽  
Mental States ◽  
Brain Regions ◽  
The Self ◽  
Similarity Analysis ◽  
Multiple Modalities ◽  
Neural Representations ◽  
Conceptual Core ◽  
Stimulus Modalities ◽  
Huge Variety

Each individual experiences mental states in their own idiosyncratic way, yet perceivers are able to accurately understand a huge variety of states across unique individuals. How do they accomplish this feat? Do people think about their own anger in the same ways as another person’s? Is reading about someone’s anxiety the same as seeing it? Here, we test the hypothesis that a common conceptual core unites mental state representations across contexts. Across three studies, participants judged the mental states of multiple targets, including a generic other, the self, a socially close other, and a socially distant other. Participants viewed mental state stimuli in multiple modalities, including written scenarios and images. Using representational similarity analysis, we found that brain regions associated with social cognition expressed stable neural representations of mental states across both targets and modalities. This suggests that people use stable models of mental states across different people and contexts.

scholarly journals Neural substrates of propranolol-induced impairments in the reconsolidation of nicotine-associated memories in smokers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiao Lin ◽  
Jiahui Deng ◽  
Kai Yuan ◽  
Qiandong Wang ◽  
Lin Liu ◽  
...  
Keyword(s):  
Neural Activity ◽  
Neural Substrates ◽  
Brain Regions ◽  
Reward Processing ◽  
Memory Reconsolidation ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Postcentral Gyrus ◽  
Propranolol Group ◽  
Propranolol Administration

AbstractThe majority of smokers relapse even after successfully quitting because of the craving to smoking after unexpectedly re-exposed to smoking-related cues. This conditioned craving is mediated by reward memories that are frequently experienced and stubbornly resistant to treatment. Reconsolidation theory posits that well-consolidated memories are destabilized after retrieval, and this process renders memories labile and vulnerable to amnestic intervention. This study tests the retrieval reconsolidation procedure to decrease nicotine craving among people who smoke. In this study, 52 male smokers received a single dose of propranolol (n = 27) or placebo (n = 25) before the reactivation of nicotine-associated memories to impair the reconsolidation process. Craving for smoking and neural activity in response to smoking-related cues served as primary outcomes. Functional magnetic resonance imaging was performed during the memory reconsolidation process. The disruption of reconsolidation by propranolol decreased craving for smoking. Reactivity of the postcentral gyrus in response to smoking-related cues also decreased in the propranolol group after the reconsolidation manipulation. Functional connectivity between the hippocampus and striatum was higher during memory reconsolidation in the propranolol group. Furthermore, the increase in coupling between the hippocampus and striatum positively correlated with the decrease in craving after the reconsolidation manipulation in the propranolol group. Propranolol administration before memory reactivation disrupted the reconsolidation of smoking-related memories in smokers by mediating brain regions that are involved in memory and reward processing. These findings demonstrate the noradrenergic regulation of memory reconsolidation in humans and suggest that adjunct propranolol administration can facilitate the treatment of nicotine dependence. The present study was pre-registered at ClinicalTrials.gov (registration no. ChiCTR1900024412).

Abstract P730: MCA Stroke Chronically Disrupts Hippocampal Activity and Cortico-Hippocampal Communication

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Zachary Ip ◽  
Gratianne Rabiller ◽  
Jiwei He ◽  
Shivalika Chavan ◽  
Yasuo Nishijima ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Memory Function ◽  
Brain Regions ◽  
Male Rats ◽  
Brain State ◽  
Signal Power ◽  
Hippocampal Function ◽  
Electrode Arrays ◽  
Mca Occlusion ◽  
Hippocampal Activity

Introduction: Cognition and memory deficits are common sequelae following middle cerebral artery (MCA) stroke, one of the most common strokes in humans. However MCA stroke does not compromise the structural integrity of the hippocampus, which is highly involved in memory function, because the MCA does not supply blood flow to the hippocampus. We previously reported on the acute effect of MCA stroke, where we observed increased hippocampal activity and cortico-hippocampal communication. Here we investigate chronic changes to local oscillations and cortico-hippocampal communication following MCA occlusion in rats two weeks and one month following stroke. Hypothesis: Cortical stroke affects remote brain regions, disrupting hippocampal function and cortico-hippocampal communication. Methods: We subjected male rats (n=28) to distal MCA occlusion compared to controls (n=19). We recorded local field potentials simultaneously from cortex and hippocampus two weeks and one month following stroke using 16-site linear electrode arrays under urethane anesthesia. We analyzed signal power, brain state, CFC, and sharp wave SPW-Rs to assess hippocampal function and cortico-hippocampal communication. Results: Our results show disruptions to local oscillations; lowered delta (1-3 Hz) signal power in the cortex and hippocampus, increased signal power in gamma (30-60 Hz) and high gamma (60-200 Hz) in cortex and hippocampus. Theta/delta brain state is disrupted, and SPW-Rs increase in power at two weeks, before returning to baseline levels at one month. Communication is also disrupted; Theta-gamma coupling, a measure of information being communicated between regions, breaks down after stroke. Conclusions: These results suggest that chronic stroke causes significant changes to hippocampal function, which can be characterized by these electrophysiological biomarkers, establishing putative targets for targeted stimulation therapies.

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