BrainMaps.org has recently implemented a new AJAX-enabled multiresolution image viewer.
What’s more, the multiresolution viewer has been released as the Brain Maps API.
Tracking and understanding the complex connections within the brain may finally reveal the neural secret of cognitive ability.
from Technology Reviews
This image from the piece graced the cover of the Journal of Neuroscience back in April. It’s a rotary shadow electron micrograph showing the cytoskeleton of a hippocampal neuron, by Bernd Knöll of the University of Tübingen and Jürgen Berger and Heinz Schwarz of the Max Planck Institute for Developmental Biology.
Chris M. Bird & Neil Burgess
The hippocampus appears to be crucial for long-term episodic memory, yet its precise role remains elusive. Electrophysiological studies in rodents offer a useful starting point for developing models of hippocampal processing in the spatial domain. Here we review one such model that points to an essential role for the hippocampus in the construction of mental images. We explain how this neural-level mechanistic account addresses some of the current controversies in the field, such as the role of the hippocampus in imagery and short-term memory, and discuss its broader implications for the neural bases of episodic memory.
Nature Reviews Neuroscience 9, 182-194 (March 2008)
N. M. van Strien, N. L. M. Cappaert & M. P. Witter
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.
Nature Reviews Neuroscience 10, 272-282 (April 2009)
Nature Reviews Neuroscience 9, 82 – 83 (February 2008)
One of the main cellular mechanisms assumed to underlie learning is long-term potentiation (LTP), an experimental form of synaptic plasticity that results in a long-lasting increase in the strength of synaptic transmission. However, prolonged synaptic stimulation in vitro eventually stops producing further LTP (also known as ‘LTP occlusion’). So, how does ongoing experience result in further learning? Clem et al. now show that the opposing actions of activated N-methyl-D-aspartate receptors (NMDARs) and metabotropic glutamate receptors (mGluRs) allow progessive synaptic strengthening during sensory-induced plasticity.
Brain Science Podcast, is an interview with Dr. Christof Koch of Cal Tech, one of the pioneers in the neurobiological study of consciousness. About two decades ago when Koch and Francis Crick began looking for what they called the neural correlates of consciousness (NCC), such a quest was considered controversial, but now the field is increasing in popularity. In this interview they talked a little about his book, The Quest for Consciousness, as well as his on-going research and his thoughts about what the future might bring.
A transcript of this interview. You can now get a PDF of the Episode Transcript.
These ideas can be read in the book: The Quest for Consciousness: A Neurobiological Approach by Christof Kock and Francis Crick
The book describes a general neurobiological framework for discovering how consciousness, the subjective mind, arises out of the flickering interactions among the neurons of the cerebral cortex and related brain areas. The book is based on collaborative work between Francis Crick and myself from 1990 until 2004.” –C. Koch (author)
Translated to spanish: La Consciencia : Una Aproximacion Neurobiologica. Editorial Ariel, S.A. – 2005.
Some links about C. Koch:
Christof Koch’s homepage
This information has been extracted from the excellent page: Brain Science Podcast. An excellent blog site to visit, directed by Ginger Campbell.
Nature Reviews Neuroscience 8, 655 (September 2007)
An interneuron’s birth date may determine its molecular and physiological phenotype.
The enormous diversity of cortical interneuron subtypes presents a challenge for our understanding of their functional roles. A study by Fishell and colleagues examines the origins of interneuron diversity during development, highlighting the importance of an interneuron’s birth order in establishing its physiological properties…
Link to the full review.
Leslie M. Kay1, and S. Murray Sherman
Trends in Neurosciences
Volume 30, Issue 2, February 2007, Pages 47-53
The mammalian olfactory system is unique in that sensory receptors synapse directly into the olfactory bulb of the forebrain without the thalamic relay that is common to all other sensory pathways. We argue that the olfactory bulb has an equivalent role to the thalamus, because the two regions have very similar structures and functions. Both the thalamus and the olfactory bulb are the final stage in sensory processing before reaching target cortical regions, at which there is a massive increase in neuron and synapse numbers. Thus, both structures act as a bottleneck that is a target for various modulatory inputs, and this arrangement enables efficient control of information flow before cortical processing occurs.
You can listen the Episode 39 of the Brain Science Podcast from Brain Science Podcast, developed by Ginger Campbell
This podcast is an interview with Dr. Michael Arbib from the University of Southern California.
Dr. Arbib’s work with functional brain imaging has established the presence of mirror neurons in the human brain. In our interview we focused on the role of mirror neurons in imitation and language. In particular I questioned Dr. Arbib about the Mirror System Hypothesis (MSH) of Language Evolution that he proposed in 1998 with Giacomo Rizzolatti. We also explored how this hypothesis diverges from the universal grammar proposed by Noam Chomsky. Dr. Arbib also shared his enthusiasm for future research and we talked about the special challenges caused by the interdisciplinary nature of modern neuroscience.
Nature Neuroscience 11, 62 – 71 (2008)
Published online: 16 December 2007 | doi:10.1038/nn2027
Kazuhiro Nakamura & Shaun F Morrison
Defending body temperature against environmental thermal challenges is one of the most fundamental homeostatic functions that are governed by the nervous system. Here we describe a somatosensory pathway that essentially constitutes the afferent arm of the thermoregulatory reflex that is triggered by cutaneous sensation of environmental temperature changes. Using in vivo electrophysiological and anatomical approaches in the rat, we found that lateral parabrachial neurons are pivotal in this pathway by glutamatergically transmitting cutaneous thermosensory signals received from spinal somatosensory neurons directly to the thermoregulatory command center, the preoptic area. This feedforward pathway mediates not only sympathetic and shivering thermogenic responses but also metabolic and cardiac responses to skin cooling challenges. Notably, this ‘thermoregulatory afferent’ pathway exists in parallel with the spinothalamocortical somatosensory pathway that mediates temperature perception. These findings make an important contribution to our understanding of both the somatosensory system and thermal homeostasis—two mechanisms that are fundamental to the nervous system and to our survival.
New research shows that the same neurons maintain memory-forming firing patterns for later recall
By Tabitha M. Powledge
…humans and rats employ the same brain mechanisms for memory, but use them somewhat differently. “We suggest that the mechanisms in the hippocampus which evolved first to allow ‘simple’ animals to navigate in space,” Buzsáki wrote, “are the same as the mechanism that allows us to navigate in ‘cognitive space’, that is, from one thought to the next.”
in Scientific American
The Journal of Neuroscience, March 14, 2007, 27(11):2837-2845; doi:10.1523/JNEUROSCI.4121-06.2007
John W. Muschamp, Juan M. Dominguez, Satoru M. Sato, Roh-Yu Shen, and Elaine M. Hull
The role of hypocretin (orexin; hcrt/orx) neurons in regulation of arousal is well established. Recently, hcrt/orx has been implicated in food reward and drug-seeking behavior. We report here that in male rats, Fos immunoreactivity (ir) in hcrt/orx neurons increases markedly during copulation, whereas castration produces decreases in hcrt/orx neuron cell counts and protein levels in a time course consistent with postcastration impairments in copulatory behavior. This effect was reversed by estradiol replacement. Immunolabeling for androgen (AR) and estrogen (ER) receptors revealed no colocalization of hcrt/orx with AR and few hcrt/orx neurons expressing ER, suggesting that hormonal regulation of hcrt/orx expression is via afferents from neurons containing those receptors. We also demonstrate that systemic administration of the orexin-1 receptor antagonist SB 334867 [N-(2-methyl-6-benzoxazolyl)-N”-1,5-naphthyridin-4-yl urea] impairs copulatory behavior. One locus for the prosexual effects of hcrt/orx may be the ventral tegmental area (VTA). We show here that hcrt-1/orx-A produces dose-dependent increases in firing rate and population activity of VTA dopamine (DA) neurons in vivo. Activation of hcrt/orx during copulation, and in turn, excitation of VTA DA neurons by hcrt/orx, may contribute to the robust increases in nucleus accumbens DA previously observed during male sexual behavior. Subsequent triple immunolabeling in anterior VTA showed that Fos-ir in tyrosine hydroxylase-positive neurons apposed to hcrt/orx fibers increases during copulation. Together, these data support the view that hcrt/orx peptides may act in a steroid-sensitive manner to facilitate the energized pursuit of natural rewards like sex via activation of the mesolimbic DA system.
Nature Reviews Neuroscience 9, 370-386. May 2008 | doi:10.1038/nrn2372
Nicholas P. Franks
The mechanisms through which general anaesthetics, an extremely diverse group of drugs, cause reversible loss of consciousness have been a long-standing mystery. Gradually, a relatively small number of important molecular targets have emerged, and how these drugs act at the molecular level is becoming clearer. Finding the link between these molecular studies and anaesthetic-induced loss of consciousness presents an enormous challenge, but comparisons with the features of natural sleep are helping us to understand how these drugs work and the neuronal pathways that they affect. Recent work suggests that the thalamus and the neuronal networks that regulate its activity are the key to understanding how anaesthetics cause loss of consciousness.
Techniques in neuroscience in jove.com
Micro-dissection of rat brain into various regions is extremely important for the study of different neurodegenerative diseases. This video demonstrates micro-dissection of four major brain regions include olfactory bulb, frontal cortex, striatum and hippocampus in fresh rat brain tissue. Useful tips for quick removal of respective regions to avoid RNA and protein degradation of the tissue are given.
Techniques in neuroscience in jove.com
The present method allows reproducible cryostat sectioning of small, difficult-to-manage, tissue pieces, such as biopsies and brain slices. We utilize a simple aluminum freezing stage to facilitate handling of tissue and a standard cryostat to routinely produce 5-10 micron serial sections from 400 micron thick brain slices.
Interview to Wolf Singer
Department of Neuroscience, Max Planck Institute
Why is the neuroscience expanding? What is the result of your research? Large amount of data: effect on neuroscience. Self-organization, emergence and complexity. Brain repair: possibilities and limitations. Theory in the contemporary neuroscience
A interesting blog about neuroscience questions, technical or experimental suggestions, and perhaps a good site to discusse ideas of our work as neuroscientists. Visit Neurodudes.
Nature Reviews Neuroscience 9, 326. May 2008 | doi:10.1038/nrn2381
The ventral tegmental area contains two distinct types of dopaminergic neuron.
Dopamine is a versatile neurotransmitter that has a role in movement and many aspects of cognition. Lammel et al. have now characterized two types of neurons in the mesocorticolimbic dopamine system that are not only anatomically segregated, with non-overlapping axonal target regions, but that also have distinct molecular and functional properties. This structured diversity of the dopamine midbrain system might contribute to the multiplicity of dopamine functions in the CNS.
Dopamine pathways in the brain are generally divided into the well-characterized mesostriatal system, which originates in the substantia nigra pars compacta (SNc) and projects to the dorsal striatum, and the mesocorticolimbic system, which starts in the ventral tegmental area (VTA) and projects to the frontal cortex and limbic areas including the amygdala and the nucleus accumbens (NAc). By retrogradely tracing mesocorticolimbic dopamine neurons, the authors established that dopamine projections in the medial prefrontal cortex, the basolateral amygdala and the core and medial shell of the NAc originate in the medial posterior part of the VTA, whereas dopamine projections to the lateral shell of the NAc originate in the more lateral portions of the VTA and the medial part of the SNc.
ORIGINAL RESEARCH PAPER
Lammel, S. et al. Unique properties of mesoprefrontal neurons within a dual mesocorticolimbic dopamine system. Neuron 57, 760–773 (2008). Pubmed