Distinct patterns of hippocampal formation activity associated with different spatial tasks: a Fos imaging study in rats

2003 ◽  
Vol 151 (4) ◽  
pp. 514-523 ◽  
Author(s):  
Trisha A. Jenkins ◽  
Eman Amin ◽  
Gordon T. Harold ◽  
John M. Pearce ◽  
John P. Aggleton
Keyword(s):  
Hippocampal Formation ◽  
Imaging Study ◽  
Spatial Tasks

scholarly journals Grey matter abnormalities in trichotillomania: morphometric magnetic resonance imaging study

2008 ◽  
Vol 193 (3) ◽  
pp. 216-221 ◽  
Author(s):  
Samuel R. Chamberlain ◽  
Lara A. Menzies ◽  
Naomi A. Fineberg ◽  
Natalia del Campo ◽  
John Suckling ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
White Matter ◽  
Magnetic Resonance ◽  
Affect Regulation ◽  
Grey Matter ◽  
Hippocampal Formation ◽  
Imaging Study ◽  
Resonance Imaging ◽  
Whole Brain ◽  
Axis I

BackgroundTrichotillomania (repetitive hair-pulling) is an Axis I psychiatric disorder whose neurobiological basis is incompletely understood. Whole-brain trichotillomania neuroimaging studies are lacking.AimsTo investigate grey and white matter abnormalities over the whole brain in patients with trichotillomania.MethodEighteen patients with DSM–IV trichotillomania and 19 healthy controls undertook structural magnetic resonance imaging after providing written informed consent. Differences in grey and white matter were investigated using computational morphometry.ResultsPatients with trichotillomania showed increased grey matter densities in the left striatum, left amygdalo-hippocampal formation, and multiple (including cingulate, supplementary motor, and frontal) cortical regions bilaterally.ConclusionsTrichotillomania was associated with structural grey matter changes in neural circuitry implicated in habit learning, cognition and affect regulation. These findings inform animal models of the disorder and highlight key regions of interest for future translational research.

scholarly journals Lifespan trajectories and relationships to memory of the macro- and microstructure of the anterior and posterior hippocampus – a longitudinal multi-modal imaging study

2019 ◽  
Author(s):  
Espen Langnes ◽  
Markus H. Sneve ◽  
Donatas Sederevicius ◽  
Inge K. Amlien ◽  
Kristine B Walhovd ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Verbal Memory ◽  
Structural Changes ◽  
Diffusion Tensor ◽  
Hippocampal Formation ◽  
Memory Performance ◽  
Memory Function ◽  
Imaging Study ◽  
Future Research ◽  
Microstructural Development

AbstractThere is evidence for a hippocampal long axis anterior-posterior (AP) differentiation in memory processing, which may have implications for the changes in episodic memory performance typically seen across development and aging. The hippocampal formation shows substantial structural changes with age, but the lifespan trajectories of hippocampal sub-regions along the AP axis are not established. The aim of the present study was to test whether the micro- and macro-structural age-trajectories of the anterior (aHC) and posterior (pHC) hippocampus are different. In a single-center longitudinal study, 1790 cognitively healthy participants, 4.1-93.4 years of age, underwent a total of 3367 MRI examinations and 3033 memory tests sessions over 1-6 time points, spanning an interval up to 11.1 years. T1-weighted scans were used to estimate the volume of aHC and pHC, and diffusion tensor imaging to measure mean diffusion (MD) within each region. We found that the macro- and microstructural lifespan-trajectories of aHC and pHC were clearly distinguishable, with partly common and partly unique variance shared with age. aHC showed a protracted period of microstructural development, while pHC microstructural development as indexed by MD was more or less completed in early childhood. In contrast, pHC showed larger unique aging-related changes. A similar aHC – pHC difference was observed for volume, although not as evident as for microstructure. All sub-regions showed age-dependent relationships to episodic memory function. For aHC micro- and macrostructure, the relationships to verbal memory performance varied significantly with age, being stronger among the older participants. Future research should disentangle the relationship between these structural properties and different memory processes – encoding vs. retrieval in particular – across the lifespan.

scholarly journals The Tolman-Eichenbaum Machine: Unifying space and relational memory through generalisation in the hippocampal formation

2019 ◽  
Author(s):  
James CR Whittington ◽  
Timothy H Muller ◽  
Shirley Mark ◽  
Guifen Chen ◽  
Caswell Barry ◽  
...  
Keyword(s):  
Hippocampal Formation ◽  
Cell Types ◽  
Structural Knowledge ◽  
Relational Memory ◽  
Grid Cells ◽  
Hippocampal Cell ◽  
Spatial Tasks ◽  
Mechanistic Understanding ◽  
Unifying Principles

The hippocampal-entorhinal system is important for spatial and relational memory tasks. We formally link these domains; provide a mechanistic understanding of the hippocampal role in generalisation; and offer unifying principles underlying many entorhinal and hippocampal cell-types. We propose medial entorhinal cells form a basis describing structural knowledge, and hippocampal cells link this basis with sensory representations. Adopting these principles, we introduce the Tolman-Eichenbaum machine (TEM). After learning, TEM entorhinal cells include grid, band, border and object-vector cells. Hippocampal cells include place and landmark cells, remapping between environments. Crucially, TEM also predicts empirically recorded representations in complex non-spatial tasks. TEM predicts hippocampal remapping is not random as previously believed. Rather structural knowledge is preserved across environments. We confirm this in simultaneously recorded place and grid cells.One Sentence SummarySimple principles of representation and generalisation unify spatial and non-spatial accounts of hippocampus and explain many cell representations.

High resolution STEM imaging study on high Tc superconductor YBa2CuaO7-x

1988 ◽  
Vol 46 ◽  
pp. 882-883
Author(s):  
H.-J. Ou ◽  
J. M. Cowley
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Grain Boundary ◽  
Strong Field ◽  
Imaging Study ◽  
Structure Defects ◽  
High Tc ◽  
High Tc Superconductor ◽  
Diffraction Patterns ◽  
Lattice Planes

Using the dedicate VG-HB5 STEM microscope, the crystal structure of high Tc superconductor of YBa2Cu3O7-x has been studied via high resolution STEM (HRSTEM) imaging and nanobeam (∽3A) diffraction patterns. Figure 1(a) and 2(a) illustrate the HRSTEM image taken at 10' times magnification along [001] direction and [100] direction, respectively. In figure 1(a), a grain boundary with strong field contrast is seen between two crystal regions A and B. The grain boundary appears to be parallel to a (110) plane, although it is not possible to determine [100] and [001] axes as it is in other regions which contain twin planes [3]. Following the horizontal lattice lines, from left to right across the grain boundary, a lattice bending of ∽4° is noticed. Three extra lattice planes, indicated by arrows, were found to terminate at the grain boundary and form dislocations. It is believed that due to different chemical composition, such structure defects occur during crystal growth. No bending is observed along the vertical lattice lines.

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