Differential propagation of ripples along the proximodistal and septotemporal axes of dorsal <scp>CA1</scp> of rats

Kumar, Mekhala; Deshmukh, Sachin S.

doi:10.1002/hipo.23211

Cited by 7 publications

(7 citation statements)

References 40 publications

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“…Rats were implanted with 3D-printed hyperdrives with linearly distributed bundle canulae angled at 35°to the ML axis to target the entire proximodistal extent of CA1 at the same septotemporal level. Data recorded during resting sessions from 8 of these rats was previously used for studying propagation of ripples in CA1 (Kumar and Deshmukh, 2020).…”

Section: Subjects and Surgerymentioning

confidence: 99%

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Distal CA1 Maintains a More Coherent Spatial Representation than Proximal CA1 When Local and Global Cues Conflict

Deshmukh

2021

J. Neurosci.

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Entorhinal cortical projections show segregation along the transverse axis of CA1, with the medial entorhinal cortex (MEC) sending denser projections to proximal CA1 (pCA1) and the lateral entorhinal cortex (LEC) sending denser projections to distal CA1 (dCA1). Previous studies have reported functional segregation along the transverse axis of CA1 correlated with the functional differences in MEC and LEC. pCA1 shows higher spatial selectivity than dCA1 in these studies. We employ a double rotation protocol, which creates an explicit conflict between the local and the global cues, to understand the differential contributions of these reference frames to the spatial code in pCA1 and dCA1 in male Long-Evans rats. We show that pCA1 and dCA1 respond differently to this local-global cue conflict. pCA1 representation splits as predicted from the strong conflicting inputs it receives from MEC and dCA3. In contrast, dCA1 rotates more in concert with the global cues. In addition, pCA1 and dCA1 display comparable levels of spatial selectivity in this study. This finding differs from the previous studies, perhaps because of richer sensory information available in our behavior arena. Together, these observations indicate that the functional segregation along proximodistal axis of CA1 is not of the amount of spatial selectivity but that of the nature of the different inputs used to create and anchor spatial representations.

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Section: Subjects and Surgerymentioning

confidence: 99%

“…Tetrodes from a single rat are represented with dots of a single color. Modified with permission from Kumar and Deshmukh (2020).…”

Section: Introductionmentioning

confidence: 99%

Distal CA1 Maintains a More Coherent Spatial Representation than Proximal CA1 When Local and Global Cues Conflict

Deshmukh

2021

J. Neurosci.

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“…Our work is based on a dataset provided by the Allen Institute (Siegle et al, 2021), this dataset enabled us to study comprehensively ripples features across the septal half of the hippocampus. Previous studies have looked at ripple propagation along the longitudinal axes of the hippocampus (Patel et al, 2013, Kumar and Deshmukh, 2020), however, the size of this dataset made it possible to unveil propagation details previously overlooked.…”

Section: Introductionmentioning

confidence: 99%

Differential ripple propagation along the hippocampal longitudinal axis

Filippo

Schmitz

2022

Preprint

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Hippocampal ripples are highly synchronous neural events critical for memory consolidation and retrieval. A minority of strong ripples has been shown to be of particular importance in situations of increased memory demands. The propagation dynamics of strong ripples inside the hippocampal formation are, however, still opaque. We analyzed ripple propagation within the hippocampal formation in a large open access dataset comprising 267 Neuropixel recordings in 49 awake, head-fixed mice. Surprisingly, strong ripples (top 10% in ripple strength) propagate differentially depending on their generation point along the hippocampal longitudinal axis. The septal hippocampal pole is able to generate longer ripples that engage more neurons and elicit spiking activity for an extended time even at considerable distances. Accordingly, a substantial portion of the variance in strong ripple duration (R2= 0.463) is explained by the ripple generation location on the longitudinal axis. Our results are consistent with a possible distinctive role of the hippocampal septal pole in conditions of high memory demand.

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“…We also evaluated the functional connectivity between CA1 of hippocampus and lateral entorhinal cortex (LEnt), which were con rmed necessary in spatial memory. Some researches had con rmed that the functional connectivity of the hippocampus with its primary cortical input, the entorhinal cortex, is organized topographically [32]. In this study, we found the functional connectivity of CA1 and LEnt was different in four groups, and the FC values were low in those groups which were performed worse in Morris water maze test.…”

Section: Discussionmentioning

confidence: 51%

MFGE8 Improved Brain Functional Connectivity Between CA1 and LEnt By Activating Efferocytosis in Hippocampus of SAE Rats

Liao

et al. 2022

Preprint

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Background: Sepsis-associated encephalopathy (SAE) is one of the most serious complications of sepsis, along with brain function and cognitive behavioral changes. The process of efferocytosis with microglia was restrained in SAE rats’ hippocampus. We have previously shown that milk fat globule EGF factor 8 protein (MFG-E8) evoked efferocytosis in SAE rats’ brain, and alleviated the inflammnation in hippocampus. The present study investigated the the contribution of MFG-E8 to the brain functional connectivity (FC) of hippocampus and lateral entorhinal cortex in SAE rats by resting-state functional MRI scan.Methods: Sixty adult male Sprague Dawley rats were divided randomly into Sham operation group, cecal ligation and puncture (CLP) group, CLP+MFGE8 group, and CLP+MFGE8+Cilengitide group. After cecal ligation and puncture (CLP) surgery, MFGE8 (3.3ug) was injected intracerebroventricularly (i.c.v.) and cilengitide (10 mg/kg) was injected intraperitoneal. The Morris water maze (MWM) and open filed test (OFT) were performed continuously for five days. Rats were detected by T2-MRI and rs-fMRI scan 8 days post-surgery, then brain tissues were taken for western blotting and pathological observation by HE stained. One-way ANOVA with Tukey’s post-test of all pair of columns was employed statistical analyses.Results: MFGE8 improved performance of neurobehavioral tests in MWM test and OFT. Expression of IL-1β and the proteins of MFGE8, Rac1, and LC3 were up regulated in CLP+MFGE8 group. On the contrary, expression of IL-6, Rac1, and LC3 were down regulated in CLP+MFGE8+cilengitide group. MFGE8 significantly decreased the hyperintense region in hippocampus detected by T2-MRI, and increased ALFF value in SAE rats’ bilateral sensory cortex, motor cortex and visual cortex by rs-fMRI. In addition, MFGE8 increased FC of CA1 and LEnt in same side of cerebral hemisphere, and the FC of CA1 and LEnt was consistent with the behavior result in Morris water maze test.Conclusions: MFGE8 activated efferocytosis with microglia and improved brain function and functional connectivity between CA1 and LEnt which were reflected in behavior tests and fMRI.

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Differential propagation of ripples along the proximodistal and septotemporal axes of dorsal CA1 of rats

Cited by 7 publications

References 40 publications

Distal CA1 Maintains a More Coherent Spatial Representation than Proximal CA1 When Local and Global Cues Conflict

Distal CA1 Maintains a More Coherent Spatial Representation than Proximal CA1 When Local and Global Cues Conflict

Differential ripple propagation along the hippocampal longitudinal axis

MFGE8 Improved Brain Functional Connectivity Between CA1 and LEnt By Activating Efferocytosis in Hippocampus of SAE Rats

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