pubmed: publications nm van ...

• Imaging hippocampal subregions with in vivo MRI: advances and limitations.

  Related Articles Imaging hippocampal subregions with in vivo MRI: advances and limitations. Nat Rev Neurosci. 2012 Jan;13(1):70 Authors: van Strien NM, Widerøe M, van de Berg WD, Uylings HB PMID: 22183437 [PubMed - indexed for MEDLINE]

• The retrosplenial cortex: intrinsic connectivity and connections with the (para)hippocampal region in the rat. An interactive connectome.

  Related Articles The retrosplenial cortex: intrinsic connectivity and connections with the (para)hippocampal region in the rat. An interactive connectome. Front Neuroinform. 2011;5:7 Authors: Sugar J, Witter MP, van Strien NM, Cappaert NL Abstract A connectome is an indispensable tool for brain researchers, since it quickly provides comprehensive knowledge of the brain's anatomical connections. Such knowledge lies at the basis of understanding network functions. Our first comprehensive and interactive account of brain connections comprised the rat hippocampal-parahippocampal network. We have now added all anatomical connections with the retrosplenial cortex (RSC) as well as the intrinsic connections of this region, because of the interesting functional overlap between these brain regions. The RSC is involved in a variety of cognitive tasks including memory, navigation, and prospective thinking, yet the exact role of the RSC and the functional differences between its subdivisions remain elusive. The connectome presented here may help to define this role by providing an unprecedented interactive and searchable overview of all connections within and between the rat RSC, parahippocampal region and hippocampal formation. PMID: 21847380 [PubMed]

• The anatomy of memory: an interactive overview of the parahippocampal-hippocampal network.

  Related Articles The anatomy of memory: an interactive overview of the parahippocampal-hippocampal network. Nat Rev Neurosci. 2009 Apr;10(4):272-82 Authors: van Strien NM, Cappaert NL, Witter MP Abstract Converging evidence suggests that each parahippocampal and hippocampal subregion contributes uniquely to the encoding, consolidation and retrieval of declarative memories, but their precise roles remain elusive. Current functional thinking does not fully incorporate the intricately connected networks that link these subregions, owing to their organizational complexity; however, such detailed anatomical knowledge is of pivotal importance for comprehending the unique functional contribution of each subregion. We have therefore developed an interactive diagram with the aim to display all of the currently known anatomical connections of the rat parahippocampal-hippocampal network. In this Review, we integrate the existing anatomical knowledge into a concise description of this network and discuss the functional implications of some relatively underexposed connections. PMID: 19300446 [PubMed - indexed for MEDLINE]

• A specific role of the human hippocampus in recall of temporal sequences.

  Related Articles A specific role of the human hippocampus in recall of temporal sequences. J Neurosci. 2009 Mar 18;29(11):3475-84 Authors: Lehn H, Steffenach HA, van Strien NM, Veltman DJ, Witter MP, Håberg AK Abstract There is a growing interest in how temporal order of episodic memories is represented within the medial temporal lobe (MTL). Animal studies suggest that the hippocampal formation (HF) is critical for retrieving the temporal order of past experiences. However, human imaging studies that have tested recency discrimination between pairs of previously encoded items have generally failed to report HF activation. We hypothesized that recalling a naturalistic sequence of past events would be particularly sensitive to HF function, attributable to greater involvement of associative processes. To test this prediction, we let subjects watch a novel movie and later, during functional magnetic resonance imaging, asked them to rearrange and "replay" scenes from the movie in correct order. To identify areas specifically involved in retrieval of temporal order, we used a control condition where subjects logically inferred the order of scenes from the same movie. Extensive MTL activation was observed during sequence recall. Activation within the right HF was specifically related to retrieval of temporal order and correlated positively with accuracy of sequence recall. Also, the bilateral parahippocampal cortex responded to retrieval of temporal order, but the activation here was not related to performance. Our study is the first to unequivocally demonstrate that correct sequence recall depends on HF. PMID: 19295153 [PubMed - indexed for MEDLINE]

• Activation of the human medial temporal lobes by stereoscopic depth cues.

  Related Articles Activation of the human medial temporal lobes by stereoscopic depth cues. Neuroimage. 2008 May 1;40(4):1815-23 Authors: van Strien NM, Scholte HS, Witter MP Abstract The perirhinal cortex (PER) is part of both the medial temporal lobe memory system (MTL) and the ventral visual stream (VVS). In the MTL, PER provides input to the hippocampal formation directly and via the entorhinal cortex (EC), whereas in the VVS, PER is considered to be at the top of the visual processing hierarchy of object information. Because of its position in both networks, PER presumably serves a role in memory and visual perception. PER's perceptual role is thought to be contingent upon the complexity of visual information, i.e., PER only becomes active in visual perception when many higher order visual cues are combined. Using high-resolution functional MRI (fMRI), we investigated the effect of varying the presence of binocular disparity, in complex visual object stimuli. Nineteen subjects were presented with movies of complex objects and a fixation cross, either with or without binocular disparity (referred to as stereo and mono condition respectively). Subjects were instructed to attentively watch the objects, but no instructions were given to memorize them. Group results showed increased activity in the MTL, among which is PER, when comparing the stereo over the mono condition (stereo > mono). Individual analysis showed dominant activation in the stereo > mono contrast in eleven out of nineteen subjects, whereas only three subjects showed dominance in the opposite contrast. We conclude that the MTL is differentially activated by the stereo and mono condition, such that activation is stronger when a complex visual object stimulus with disparity is presented. PMID: 18353684 [PubMed - indexed for MEDLINE]

• A structural MRI study in monozygotic twins concordant or discordant for attention/hyperactivity problems: evidence for genetic and environmental heterogeneity in the developing brain.

  Related Articles A structural MRI study in monozygotic twins concordant or discordant for attention/hyperactivity problems: evidence for genetic and environmental heterogeneity in the developing brain. Neuroimage. 2007 Apr 15;35(3):1004-20 Authors: van 't Ent D, Lehn H, Derks EM, Hudziak JJ, Van Strien NM, Veltman DJ, De Geus EJ, Todd RD, Boomsma DI Abstract Several structural brain abnormalities have been reported in patients with Attention Deficit Hyperactivity Disorder (ADHD). However, the etiology of these brain changes is still unclear. To investigate genetic and environmental influences on ADHD related neurobiological changes, we performed Voxel-Based Morphometry on MRI scans from monozygotic (MZ) twins selected from a large longitudinal population database to be highly concordant or highly discordant for ratings on the Child Behavior Checklist Attention Problem scale (CBCL-AP). Children scoring low on the CBCL-AP are at low risk for ADHD, whereas children scoring high on this scale are at high-risk for ADHD. Brain differences between concordant high-risk twin pairs and concordant low-risk twin pairs likely reflect the genetic risk for ADHD; brain differences between the low-risk and high-risk twins from discordant MZ twin pairs reflect the environmental risk for ADHD. A major difference between comparisons of high and low-risk twins from concordant pairs and high/low twins from discordant pairs was found for the prefrontal lobes. The concordant high-risk pairs showed volume loss in orbitofrontal subdivisions. High-risk members from the discordant twin pairs exhibited volume reduction in the right inferior dorsolateral prefontal cortex. In addition, the posterior corpus callosum was compromised in concordant high-risk pairs, only. Our findings indicate that inattention and hyperactivity symptoms are associated with anatomical abnormalities of a distributed action-attentional network. Different brain areas of this network appear to be affected in inattention/hyperactivity caused by genetic (i.e., high concordant MZ pairs) vs. environmental (i.e., high-low discordant MZ pairs) risk factors. These results provide clues that further our understanding of brain alterations in ADHD. PMID: 17346990 [PubMed - indexed for MEDLINE]

• Rap1 couples cAMP signaling to a distinct pool of p42/44MAPK regulating excitability, synaptic plasticity, learning, and memory.

  Related Articles Rap1 couples cAMP signaling to a distinct pool of p42/44MAPK regulating excitability, synaptic plasticity, learning, and memory. Neuron. 2003 Jul 17;39(2):309-25 Authors: Morozov A, Muzzio IA, Bourtchouladze R, Van-Strien N, Lapidus K, Yin D, Winder DG, Adams JP, Sweatt JD, Kandel ER Abstract Learning-induced synaptic plasticity commonly involves the interaction between cAMP and p42/44MAPK. To investigate the role of Rap1 as a potential signaling molecule coupling cAMP and p42/44MAPK, we expressed an interfering Rap1 mutant (iRap1) in the mouse forebrain. This expression selectively decreased basal phosphorylation of a membrane-associated pool of p42/44MAPK, impaired cAMP-dependent LTP in the hippocampal Schaffer collateral pathway induced by either forskolin or theta frequency stimulation, decreased complex spike firing, and reduced the p42/44MAPK-mediated phosphorylation of the A-type potassium channel Kv4.2. These changes correlated with impaired spatial memory and context discrimination. These results indicate that Rap1 couples cAMP signaling to a selective membrane-associated pool of p42/44MAPK to control excitability of pyramidal cells, the early and late phases of LTP, and the storage of spatial memory. PMID: 12873387 [PubMed - indexed for MEDLINE]