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  1. Article ; Online: Dual projecting cells linking thalamic and cortical communication routes between the medial prefrontal cortex and hippocampus.

    Schlecht, Maximilian / Jayachandran, Maanasa / Rasch, Gabriela E / Allen, Timothy A

    Neurobiology of learning and memory

    2022  Volume 188, Page(s) 107586

    Abstract: The interactions between the medial prefrontal cortex (mPFC) and the hippocampus (HC) are critical for memory and decision making and have been specifically implicated in several neurological disorders including schizophrenia, epilepsy, frontotemporal ... ...

    Abstract The interactions between the medial prefrontal cortex (mPFC) and the hippocampus (HC) are critical for memory and decision making and have been specifically implicated in several neurological disorders including schizophrenia, epilepsy, frontotemporal dementia, and Alzheimer's disease. The ventral midline thalamus (vmThal), and lateral entorhinal cortex and perirhinal cortex (LEC/PER) constitute major communication pathways that facilitate mPFC-HC interactions in memory. Although vmThal and LEC/PER circuits have been delineated separately we sought to determine whether these two regions share cell-specific inputs that could influence both routes simultaneously. To do this we used a dual fluorescent retrograde tracing approach using cholera toxin subunit-B (CTB-488 and CTB-594) with injections targeting vmThal and the LEC/PER in rats. Retrograde cell body labeling was examined in key regions of interest within the mPFC-HC system including: (1) mPFC, specifically anterior cingulate cortex (ACC), dorsal and ventral prelimbic cortex (dPL, vPL), and infralimbic cortex (IL); (2) medial and lateral septum (MS, LS); (3) subiculum (Sub) along the dorsal-ventral and proximal-distal axes; and (4) LEC and medial entorhinal cortex (MEC). Results showed that dual vmThal-LEC/PER-projecting cell populations are found in MS, vSub, and the shallow layers II/III of LEC and MEC. We did not find any dual projecting cells in mPFC or in the cornu ammonis (CA) subfields of the HC. Thus, mPFC and HC activity is sent to vmThal and LEC/PER via non-overlapping projection cell populations. Importantly, the dual projecting cell populations in MS, vSub, and EC are in a unique position to simultaneously influence both cortical and thalamic mPFC-HC pathways critical to memory. SIGNIFICANCE STATEMENT: The interactions between mPFC and HC are critical for learning and memory, and dysfunction within this circuit is implicated in various neurodegenerative and psychiatric diseases. mPFC-HC interactions are mediated through multiple communication pathways including a thalamic hub through the vmThal and a cortical hub through lateral entorhinal cortex and perirhinal cortex. Our data highlight newly identified dual projecting cell populations in the septum, Sub, and EC of the rat brain. These dual projecting cells may have the ability to modify the information flow within the mPFC-HC circuit through synchronous activity, and thus offer new cell-specific circuit targets for basic and translational studies in memory.
    MeSH term(s) Animals ; Communication ; Entorhinal Cortex ; Female ; Hippocampus/physiology ; Male ; Midline Thalamic Nuclei/physiology ; Neural Pathways ; Prefrontal Cortex/physiology ; Rats ; Thalamus/physiology
    Language English
    Publishing date 2022-01-16
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1223366-3
    ISSN 1095-9564 ; 1074-7427
    ISSN (online) 1095-9564
    ISSN 1074-7427
    DOI 10.1016/j.nlm.2022.107586
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Nucleus reuniens transiently synchronizes memory networks at beta frequencies.

    Jayachandran, Maanasa / Viena, Tatiana D / Garcia, Andy / Veliz, Abdiel Vasallo / Leyva, Sofia / Roldan, Valentina / Vertes, Robert P / Allen, Timothy A

    Nature communications

    2023  Volume 14, Issue 1, Page(s) 4326

    Abstract: Episodic memory-based decision-making requires top-down medial prefrontal cortex and hippocampal interactions. This integrated prefrontal-hippocampal memory state is thought to be organized by synchronized network oscillations and mediated by ... ...

    Abstract Episodic memory-based decision-making requires top-down medial prefrontal cortex and hippocampal interactions. This integrated prefrontal-hippocampal memory state is thought to be organized by synchronized network oscillations and mediated by connectivity with the thalamic nucleus reuniens (RE). Whether and how the RE synchronizes prefrontal-hippocampal networks in memory, however, remains unknown. Here, we recorded local field potentials from the prefrontal-RE-hippocampal network while rats engaged in a nonspatial sequence memory task, thereby isolating memory-related activity from running-related oscillations. We found that synchronous prefrontal-hippocampal beta bursts (15-30 Hz) dominated during memory trials, whereas synchronous theta activity (6-12 Hz) dominated during non-memory-related running. Moreover, RE beta activity appeared first, followed by prefrontal and hippocampal synchronized beta, suggesting that prefrontal-hippocampal beta could be driven by the RE. To test whether the RE is capable of driving prefrontal-hippocampal beta synchrony, we used an optogenetic approach (retroAAV-ChR2). RE activation induced prefrontal-hippocampal beta coherence and reduced theta coherence, matching the observed memory-driven network state in the sequence task. These findings are the first to demonstrate that the RE contributes to memory by driving transient synchronized beta in the prefrontal-hippocampal system, thereby facilitating interactions that underlie memory-based decision-making.
    MeSH term(s) Rats ; Animals ; Midline Thalamic Nuclei/physiology ; Prefrontal Cortex/physiology ; Hippocampus/physiology ; Thalamic Nuclei ; Neural Pathways/physiology
    Language English
    Publishing date 2023-07-19
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-023-40044-z
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Critical Review of Noninvasive Optical Technologies for Wound Imaging.

    Jayachandran, Maanasa / Rodriguez, Suset / Solis, Elizabeth / Lei, Jiali / Godavarty, Anuradha

    Advances in wound care

    2016  Volume 5, Issue 8, Page(s) 349–359

    Abstract: Significance: ...

    Abstract Significance:
    Language English
    Publishing date 2016-08-01
    Publishing country United States
    Document type Review ; Journal Article
    ZDB-ID 2650541-1
    ISSN 2162-1934 ; 2162-1918
    ISSN (online) 2162-1934
    ISSN 2162-1918
    DOI 10.1089/wound.2015.0678
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Prefrontal Pathways Provide Top-Down Control of Memory for Sequences of Events.

    Jayachandran, Maanasa / Linley, Stephanie B / Schlecht, Maximilian / Mahler, Stephen V / Vertes, Robert P / Allen, Timothy A

    Cell reports

    2019  Volume 28, Issue 3, Page(s) 640–654.e6

    Abstract: We remember our lives as sequences of events, but it is unclear how these memories are controlled during retrieval. In rats, the medial prefrontal cortex (mPFC) is positioned to influence sequence memory through extensive top-down inputs to regions ... ...

    Abstract We remember our lives as sequences of events, but it is unclear how these memories are controlled during retrieval. In rats, the medial prefrontal cortex (mPFC) is positioned to influence sequence memory through extensive top-down inputs to regions heavily interconnected with the hippocampus, notably the nucleus reuniens of the thalamus (RE) and perirhinal cortex (PER). Here, we used an hM4Di synaptic-silencing approach to test our hypothesis that specific mPFC→RE and mPFC→PER projections regulate sequence memory retrieval. First, we found non-overlapping populations of mPFC cells project to RE and PER. Second, suppressing mPFC activity impaired sequence memory. Third, inhibiting mPFC→RE and mPFC→PER pathways effectively abolished sequence memory. Finally, a sequential lag analysis showed that the mPFC→RE pathway contributes to a working memory retrieval strategy, whereas the mPFC→PER pathway supports a temporal context memory retrieval strategy. These findings demonstrate that mPFC→RE and mPFC→PER pathways serve as top-down mechanisms that control distinct sequence memory retrieval strategies.
    MeSH term(s) Animals ; Clozapine/analogs & derivatives ; Clozapine/pharmacology ; GABA Antagonists/pharmacology ; Hippocampus/physiology ; Memory, Short-Term/drug effects ; Memory, Short-Term/physiology ; Midline Thalamic Nuclei/drug effects ; Midline Thalamic Nuclei/physiology ; Neural Pathways/physiology ; Perirhinal Cortex/drug effects ; Perirhinal Cortex/physiology ; Prefrontal Cortex/cytology ; Prefrontal Cortex/drug effects ; Prefrontal Cortex/physiology ; Rats ; Rats, Long-Evans ; Receptor, Muscarinic M4/drug effects ; Receptor, Muscarinic M4/metabolism ; Serotonin Antagonists/pharmacology
    Chemical Substances GABA Antagonists ; Receptor, Muscarinic M4 ; Serotonin Antagonists ; Clozapine (J60AR2IKIC) ; clozapine N-oxide (MZA8BK588J)
    Language English
    Publishing date 2019-07-20
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2649101-1
    ISSN 2211-1247 ; 2211-1247
    ISSN (online) 2211-1247
    ISSN 2211-1247
    DOI 10.1016/j.celrep.2019.06.053
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Assessing the Healing of Venous Leg Ulcers Using a Noncontact Near-Infrared Optical Imaging Approach.

    Lei, Jiali / Rodriguez, Suset / Jayachandran, Maanasa / Solis, Elizabeth / Epnere, Katrina / Perez-Clavijo, Francisco / Wigley, Stephen / Godavarty, Anuradha

    Advances in wound care

    2018  Volume 7, Issue 4, Page(s) 134–143

    Abstract: Objective: ...

    Abstract Objective:
    Language English
    Publishing date 2018-04-19
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2650541-1
    ISSN 2162-1934 ; 2162-1918
    ISSN (online) 2162-1934
    ISSN 2162-1918
    DOI 10.1089/wound.2017.0745
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: RatHat: A Self-Targeting Printable Brain Implant System.

    Allen, Leila M / Jayachandran, Maanasa / Viena, Tatiana D / Su, Meifung / McNaughton, Bruce L / Allen, Timothy A

    eNeuro

    2020  Volume 7, Issue 2

    Abstract: There has not been a major change in how neuroscientists approach stereotaxic methods in decades. Here, we present a new stereotaxic method that provides an alternative approach to a traditional u-frame stereotaxic device and reduces costs, surgical time, ...

    Abstract There has not been a major change in how neuroscientists approach stereotaxic methods in decades. Here, we present a new stereotaxic method that provides an alternative approach to a traditional u-frame stereotaxic device and reduces costs, surgical time, and aids repeatability. The RatHat brain implantation system is a 3D-printable stereotaxic device for rats that is fabricated prior to surgery and fits to the shape of the skull. RatHat builds are directly implanted into the brain without the need for head-leveling or coordinate-mapping during surgery. The RatHat can be used in conjunction with the traditional u-frame stereotaxic device, but does not require the use of a micromanipulator for successful implantations. Each RatHat contains several primary components including the implant for mounting intracranial components, the surgical stencil for targeting drill sites, and the protective cap for preventing damage from impacts and debris. Each component serves a unique function and can be used together or separately. We demonstrate the feasibility of the RatHat in four different proof-of-principle experiments: (1) a three-pole cannula apparatus, (2) an optrode-electrode assembly, (3) a fixed-electrode array, and (4) a tetrode hyperdrive. Implants were successful, durable, and long-lasting (up to nine months). RatHat print files are easily created, can be modified in computer aided design (CAD) software for a variety of applications, and are easily shared, contributing to open science goals and replications. The RatHat has been adapted to multiple experimental paradigms in our lab and should be a useful new way to conduct stereotaxic implant surgeries in rodents.
    MeSH term(s) Animals ; Brain/surgery ; Head ; Imaging, Three-Dimensional ; Rats ; Software ; Stereotaxic Techniques
    Language English
    Publishing date 2020-04-13
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2800598-3
    ISSN 2373-2822 ; 2373-2822
    ISSN (online) 2373-2822
    ISSN 2373-2822
    DOI 10.1523/ENEURO.0538-19.2020
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Awake delta and theta-rhythmic hippocampal network modes during intermittent locomotor behaviors in the rat.

    Schultheiss, Nathan W / Schlecht, Maximilian / Jayachandran, Maanasa / Brooks, Deborah R / McGlothan, Jennifer L / Guilarte, Tomás R / Allen, Timothy A

    Behavioral neuroscience

    2020  Volume 134, Issue 6, Page(s) 529–546

    Abstract: Delta-frequency network activity is commonly associated with sleep or behavioral disengagement accompanied by a dearth of cortical spiking, but delta in awake behaving animals is not well understood. We show that hippocampal (HC) synchronization in the ... ...

    Abstract Delta-frequency network activity is commonly associated with sleep or behavioral disengagement accompanied by a dearth of cortical spiking, but delta in awake behaving animals is not well understood. We show that hippocampal (HC) synchronization in the delta frequency band (1-4 Hz) is related to animals' locomotor behavior using detailed analyses of the HC local field potential (LFP) and simultaneous head- and body-tracking data. In contrast to running-speed modulation of the theta rhythm (6-10 Hz), delta was most prominent when animals were stationary or moving slowly, that is, when theta and fast gamma (65-120 Hz) were weak, and often developed rapidly when animals paused briefly between runs. We next combined time-frequency decomposition of the LFP with hierarchical clustering algorithms to categorize momentary estimations of the power spectral density (PSD) into putative modes of HC activity. Delta and theta power were strikingly orthogonal across spectral modes, as well as across bouts of precisely defined running and stationary behavior. Delta-band and theta-band coherences between HC recording sites were monotonically related to theta-delta ratios across modes; and whereas theta coherence between HC and medial prefrontal cortex (mPFC) increased during running, delta-band coherence between mPFC and HC increased during stationary bouts. Taken together, our findings suggest that delta-dominated network modes (and corresponding mPFC-HC couplings) represent functionally distinct circuit dynamics that are temporally and behaviorally interspersed among theta-dominated modes during navigation. As such, delta modes could play a fundamental role in coordinating encoding and retrieval mechanisms or decision-making processes at a timescale that segments event sequences within behavioral episodes. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
    MeSH term(s) Animals ; Delta Rhythm ; Hippocampus ; Locomotion ; Male ; Prefrontal Cortex ; Rats ; Rats, Long-Evans ; Theta Rhythm ; Wakefulness
    Language English
    Publishing date 2020-07-16
    Publishing country United States
    Document type Journal Article
    ZDB-ID 230159-3
    ISSN 1939-0084 ; 0735-7044
    ISSN (online) 1939-0084
    ISSN 0735-7044
    DOI 10.1037/bne0000409
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Prefrontal Pathways Provide Top-Down Control of Memory for Sequences of Events

    Maanasa Jayachandran / Stephanie B. Linley / Maximilian Schlecht / Stephen V. Mahler / Robert P. Vertes / Timothy A. Allen

    Cell Reports, Vol 28, Iss 3, Pp 640-654.e

    2019  Volume 6

    Abstract: ... that control distinct sequence memory retrieval strategies. : Jayachandran et al. demonstrate that the medial ...

    Abstract Summary: We remember our lives as sequences of events, but it is unclear how these memories are controlled during retrieval. In rats, the medial prefrontal cortex (mPFC) is positioned to influence sequence memory through extensive top-down inputs to regions heavily interconnected with the hippocampus, notably the nucleus reuniens of the thalamus (RE) and perirhinal cortex (PER). Here, we used an hM4Di synaptic-silencing approach to test our hypothesis that specific mPFC→RE and mPFC→PER projections regulate sequence memory retrieval. First, we found non-overlapping populations of mPFC cells project to RE and PER. Second, suppressing mPFC activity impaired sequence memory. Third, inhibiting mPFC→RE and mPFC→PER pathways effectively abolished sequence memory. Finally, a sequential lag analysis showed that the mPFC→RE pathway contributes to a working memory retrieval strategy, whereas the mPFC→PER pathway supports a temporal context memory retrieval strategy. These findings demonstrate that mPFC→RE and mPFC→PER pathways serve as top-down mechanisms that control distinct sequence memory retrieval strategies. : Jayachandran et al. demonstrate that the medial prefrontal cortex has separate projections to the nucleus reuniens of the thalamus and perirhinal cortex. The authors then demonstrate that these pathways differentially control how an episodic-like memory is retrieved. Keywords: thalamus, nucleus reuniens, perirhinal cortex, DREADDs, episodic memory, memory retrieval, working memory, temporal context, cognitive control, hippocampus
    Keywords Biology (General) ; QH301-705.5
    Subject code 612
    Language English
    Publishing date 2019-07-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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