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Frequency matters: how changes in hippocampal theta frequency can influence temporal coding, anxiety-reduction, and memory (2023)
Journal Article
Hines, M., Poulter, S., Douchamps, V., Pibiri, F., McGregor, A., & Lever, C. (2023). Frequency matters: how changes in hippocampal theta frequency can influence temporal coding, anxiety-reduction, and memory. Frontiers in Systems Neuroscience, 16, https://doi.org/10.3389/fnsys.2022.998116

Hippocampal theta frequency is a somewhat neglected topic relative to theta power, phase, coherence, and cross-frequency coupling. Accordingly, here we review and present new data on variation in hippocampal theta frequency, focusing on functional as... Read More about Frequency matters: how changes in hippocampal theta frequency can influence temporal coding, anxiety-reduction, and memory.

Vector trace cells in the subiculum of the hippocampal formation (2020)
Journal Article
Poulter, S., Lee, S. A., Dachtler, J., Wills, T. J., & Lever, C. (2021). Vector trace cells in the subiculum of the hippocampal formation. Nature Neuroscience, 24, 266-275. https://doi.org/10.1038/s41593-020-00761-w

Successfully navigating in physical or semantic space requires a neural representation of allocentric (map-based) vectors to boundaries, objects and goals. Cognitive processes such as path-planning and imagination entail the recall of vector represen... Read More about Vector trace cells in the subiculum of the hippocampal formation.

Distinct and combined responses to environmental geometry and features in a working-memory reorientation task in rats and chicks (2020)
Journal Article
Lee, S. A., Austen, J. M., Sovrano, V. A., Vallortigara, G., McGregor, A., & Lever, C. (2020). Distinct and combined responses to environmental geometry and features in a working-memory reorientation task in rats and chicks. Scientific Reports, 10(1), Article 7508. https://doi.org/10.1038/s41598-020-64366-w

The original provocative formulation of the ‘geometric module’ hypothesis was based on a working-memory task in rats which suggested that spontaneous reorientation behavior is based solely on the environmental geometry and is impervious to featural c... Read More about Distinct and combined responses to environmental geometry and features in a working-memory reorientation task in rats and chicks.

En route to delineating hippocampal roles in spatial learning (2019)
Journal Article
Poulter, S., Austen, J. M., Kosaki, Y., Dachtler, J., Lever, C., & McGregor, A. (2019). En route to delineating hippocampal roles in spatial learning. Behavioural Brain Research, 369, Article 111936. https://doi.org/10.1016/j.bbr.2019.111936

The precise role played by the hippocampus in spatial learning tasks, such as the Morris Water Maze (MWM), is not fully understood. One theory is that the hippocampus is not required for ‘knowing where’ but rather is crucial in ‘getting there’. To ex... Read More about En route to delineating hippocampal roles in spatial learning.

The neurobiology of mammalian navigation (2018)
Journal Article
Poulter, S., Hartley, T., & Lever, C. (2018). The neurobiology of mammalian navigation. Current Biology, 28(17), R1023-R1042. https://doi.org/10.1016/j.cub.2018.05.050

Mammals have evolved specialized brain systems to support efficient navigation within diverse habitats and over varied distances, but while navigational strategies and sensory mechanisms vary across species, core spatial components appear to be widel... Read More about The neurobiology of mammalian navigation.

Hippocampal CA1 activity correlated with the distance to the goal and navigation performance (2017)
Journal Article
Spiers, H. J., Olafsdottir, H. F., & Lever, C. (2018). Hippocampal CA1 activity correlated with the distance to the goal and navigation performance. Hippocampus, 28(9), 644-658. https://doi.org/10.1002/hipo.22813

Coding the distance to a future goal is an important function of a neural system supporting navigation. While some evidence indicates the hippocampus increases activity with proximity to the goal, others have found activity to decrease with proximity... Read More about Hippocampal CA1 activity correlated with the distance to the goal and navigation performance.

Reconciling the different faces of hippocampal theta: The role of theta oscillations in cognitive, emotional and innate behaviors (2017)
Journal Article
Korotkova, T., Ponomarenko, A., Monaghan, C. K., Poulter, S. L., Cacucci, F., Wills, T., …Lever, C. (2017). Reconciling the different faces of hippocampal theta: The role of theta oscillations in cognitive, emotional and innate behaviors. Neuroscience & Biobehavioral Reviews, 85, 65-80. https://doi.org/10.1016/j.neubiorev.2017.09.004

The theta oscillation (5–10 Hz) is a prominent behavior-specific brain rhythm. This review summarizes studies showing the multifaceted role of theta rhythm in cognitive functions, including spatial coding, time coding and memory, exploratory locomoti... Read More about Reconciling the different faces of hippocampal theta: The role of theta oscillations in cognitive, emotional and innate behaviors.

Allocentric Spatial Memory Testing Predicts Conversion from Mild Cognitive Impairment to Dementia: An Initial Proof-of-Concept Study (2016)
Journal Article
Wood, R., Moodley, K., Lever, C., Minati, L., & Chan, D. (2016). Allocentric Spatial Memory Testing Predicts Conversion from Mild Cognitive Impairment to Dementia: An Initial Proof-of-Concept Study. Frontiers in Neurology, 7, Article 215. https://doi.org/10.3389/fneur.2016.00215

The hippocampus is one of the first regions to exhibit neurodegeneration in Alzheimer’s disease (AD), and knowledge of its role in allocentric spatial memory may therefore aid early diagnosis of AD. The 4 Mountains Test (4MT) is a short and easily ad... Read More about Allocentric Spatial Memory Testing Predicts Conversion from Mild Cognitive Impairment to Dementia: An Initial Proof-of-Concept Study.

Heterozygous deletion of α-neurexin I or α-neurexin II results in behaviors relevant to autism and schizophrenia (2015)
Journal Article
Dachtler, J., Ivorra, J., Rowland, T., Lever, C., Rodgers, R., & Clapcote, S. (2015). Heterozygous deletion of α-neurexin I or α-neurexin II results in behaviors relevant to autism and schizophrenia. Behavioral Neuroscience, 129(6), 765-776. https://doi.org/10.1037/bne0000108

The neurexins are a family of presynaptic cell adhesion molecules. Human genetic studies have found heterozygous deletions affecting NRXN1 and NRXN2, encoding α-neurexin I (Nrxn1α) and α-neurexin II (Nrxn2α), in individuals with autism spectrum disor... Read More about Heterozygous deletion of α-neurexin I or α-neurexin II results in behaviors relevant to autism and schizophrenia.

The Behavioural Inhibition System, anxiety and hippocampal volume in a non-clinical population (2014)
Journal Article
Levita, L., Bois, C., Healey, A., Smyllie, E., Papakonstantinou, E., Hartley, T., & Lever, C. (2014). The Behavioural Inhibition System, anxiety and hippocampal volume in a non-clinical population. Biology of mood & anxiety disorders, 4, Article 4. https://doi.org/10.1186/2045-5380-4-4

Background: Animal studies have suggested that the hippocampus may play an important role in anxiety as part of the Behavioural Inhibition System (BIS), which mediates reactivity to threat and punishment and can predict an individual’s response to an... Read More about The Behavioural Inhibition System, anxiety and hippocampal volume in a non-clinical population.

Boundary coding in the rat subiculum (2014)
Journal Article
Stewart, S., Jeewajee, A., Wills, T., Burgess, N., & Lever, C. (2014). Boundary coding in the rat subiculum. Philosophical Transactions of the Royal Society B: Biological Sciences, 369(1635), Article 20120514. https://doi.org/10.1098/rstb.2012.0514

The spatial mapping function of the hippocampal formation is likely derived from two sets of information: one based on the external environment and the other based on self-motion. Here, we further characterize ‘boundary vector cells’ (BVCs) in the ra... Read More about Boundary coding in the rat subiculum.

Theta phase precession of grid and place cell firing in open environments (2014)
Journal Article
Jeewajee, A., Barry, C., Douchamps, V., Manson, D., Lever, C., & Burgess, N. (2014). Theta phase precession of grid and place cell firing in open environments. Philosophical Transactions of the Royal Society B: Biological Sciences, 369(1635), Article 20120532. https://doi.org/10.1098/rstb.2012.0532

Place and grid cells in the rodent hippocampal formation tend to fire spikes at successively earlier phases relative to the local field potential theta rhythm as the animal runs through the cell's firing field on a linear track. However, this ‘phase... Read More about Theta phase precession of grid and place cell firing in open environments.

Space in the brain: how the hippocampal formation supports spatial cognition (2013)
Journal Article
Hartley, T., Lever, C., Burgess, N., & O'Keefe, J. (2014). Space in the brain: how the hippocampal formation supports spatial cognition. Philosophical Transactions of the Royal Society B: Biological Sciences, 369(1635), Article 20120510. https://doi.org/10.1098/rstb.2012.0510

Over the past four decades, research has revealed that cells in the hippocampal formation provide an exquisitely detailed representation of an animal's current location and heading. These findings have provided the foundations for a growing understan... Read More about Space in the brain: how the hippocampal formation supports spatial cognition.

How environment geometry affects grid cell symmetry and what we can learn from it (2013)
Journal Article
Krupic, J., Bauza, M., Burton, S., Lever, C., & O'Keefe, J. (2014). How environment geometry affects grid cell symmetry and what we can learn from it. Philosophical Transactions of the Royal Society B: Biological Sciences, 369(1635), Article 20130188. https://doi.org/10.1098/rstb.2013.0188

The mammalian hippocampal formation provides neuronal representations of environmental location but the underlying mechanisms are unclear. The majority of cells in medial entorhinal cortex and parasubiculum show spatially periodic firing patterns. Gr... Read More about How environment geometry affects grid cell symmetry and what we can learn from it.

Novelty and anxiolytic drugs dissociate two components of hippocampal theta in behaving rats (2013)
Journal Article
Wells, C., Amos, D., Jeewajee, A., Douchamps, V., Rodgers, R., O’Keefe, J., …Lever, C. (2013). Novelty and anxiolytic drugs dissociate two components of hippocampal theta in behaving rats. Journal of Neuroscience, 33(20), 8650-8667. https://doi.org/10.1523/jneurosci.5040-12.2013

Hippocampal processing is strongly implicated in both spatial cognition and anxiety and is temporally organized by the theta rhythm. However, there has been little attempt to understand how each type of processing relates to the other in behaving ani... Read More about Novelty and anxiolytic drugs dissociate two components of hippocampal theta in behaving rats.

Evidence for encoding versus retrieval scheduling in the hippocampus by theta phase and acetylcholine (2013)
Journal Article
Douchamps, V., Jeewajee, A., Blundell, P., Burgess, N., & Lever, C. (2013). Evidence for encoding versus retrieval scheduling in the hippocampus by theta phase and acetylcholine. Journal of Neuroscience, 33(20), 8689-8704. https://doi.org/10.1523/jneurosci.4483-12.2013

The formation of new memories requires new information to be encoded in the face of proactive interference from the past. Two solutions have been proposed for hippocampal region CA1: (1) acetylcholine, released in novelty, selectively suppresses exci... Read More about Evidence for encoding versus retrieval scheduling in the hippocampus by theta phase and acetylcholine.

A specific role for septohippocampal acetylcholine in memory? (2012)
Journal Article
Easton, A., Douchamps, V., Eacott, M., & Lever, C. (2012). A specific role for septohippocampal acetylcholine in memory?. Neuropsychologia, 50(13), 3156-3168. https://doi.org/10.1016/j.neuropsychologia.2012.07.022

Acetylcholine has long been implicated in memory, including hippocampal-dependent memory, but the specific role for this neurotransmitter is difficult to identify in human neuropsychology. Here, we review the evidence for a mechanistic model of acety... Read More about A specific role for septohippocampal acetylcholine in memory?.

Which memory task for my mouse? A systematic review of spatial memory performance in the Tg2576 Alzheimer's mouse model (2011)
Journal Article
Stewart, S., Cacucci, F., & Lever, C. (2011). Which memory task for my mouse? A systematic review of spatial memory performance in the Tg2576 Alzheimer's mouse model. Journal of Alzheimer's Disease, 26(1), 105-126. https://doi.org/10.3233/jad-2011-101827

We review studies testing performance on tasks putatively tapping spatial memory in the Tg2576 mouse model of Alzheimer's disease (AD). This model exhibits age-dependent elevation of amyloid-β in the hippocampal formation and elsewhere in the brain.... Read More about Which memory task for my mouse? A systematic review of spatial memory performance in the Tg2576 Alzheimer's mouse model.