Table of contents

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Science on the go p401


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News and Views

Preventing dehydration during sleep pp403 - 404

Christopher S Colwell


Vasopressin release increases late in sleep. Suprachiasmatic clock neurons modulate osmosensory synapses onto vasopressin neurons to facilitate osmoregulated vasopressin release, reports a study in this issue. This explains the increased late-night vasopressin release, and such facilitation prevents dehydration during sleep.

See also: Article by Trudel & Bourque

Manipulating the brain with epigenetics pp405 - 406

Edward Korzus


A study finds that the DNA methylation enzymes Dnmt1 and Dnmt3a are needed to maintain the epigenetic landscape in nondividing, postmitotic neurons and that this process is required for normal learning and memory.

See also: Article by Feng et al.

Mouse brains wired for empathy? pp406 - 408

François Grenier & Andreas Lüthi


A study in this issue reports that mice can be fear conditioned through observation of other mice receiving aversive stimuli and identifies some of the brain regions involved in this observational fear learning.

See also: Article by Jeon et al.

Protecting endangered memories pp408 - 410

Guillén Fernández & Marijn C W Kroes


Memories are continually adapted by ongoing experience. A study now suggests that the reactivation of previously stored memories during the formation of new memories is a critical mechanism for determining memory survival.

See also: Article by Kuhl et al.

Speedy rod signaling p410

Annette Markus


See also: Brief Communication by Li et al.


Brief Communications

Microglial Cx3cr1 knockout prevents neuron loss in a mouse model of Alzheimer's disease pp411 - 413

Martin Fuhrmann, Tobias Bittner, Christian K E Jung, Steffen Burgold, Richard M Page, Gerda Mitteregger, Christian Haass, Frank M LaFerla, Hans Kretzschmar & Jochen Herms


Using two-photon imaging in a transgenic mouse model of Alzheimer's disease, the authors find that microglia, the resident macrophages of the brain, surround neurons prior to nerve cell death. They also find that inactivation of the microglial chemokine receptor CX3CR1, which is critical in neuron-microglia communication, prevents neuron loss.

A fast rod photoreceptor signaling pathway in the mammalian retina pp414 - 416

Wei Li, Shan Chen & Steven H DeVries


Rod photoreceptors contact Off cone bipolar cells, but it has been unclear what the function of this pathway is. The authors recorded from pairs of rods and Off cone bipolar cells in the ground squirrel and show that this new pathway can mediate rapid signaling in the retina.

See also: News and Views by Markus

Cortical representations of bodies and faces are strongest in commonly experienced configurations pp417 - 418

Annie W-Y Chan, Dwight J Kravitz, Sandra Truong, Joseph Arizpe & Chris I Baker


Faces and bodies are highly familiar visual stimuli that occur in stereotypical configurations. Using fMRI, the authors find that face and body representations are strongest and most distinct in the commonly experienced combinations of visual field and side of body.

Mesolimbic dopamine reward system hypersensitivity in individuals with psychopathic traits pp419 - 421

Joshua W Buckholtz, Michael T Treadway, Ronald L Cowan, Neil D Woodward, Stephen D Benning, Rui Li, M Sib Ansari, Ronald M Baldwin, Ashley N Schwartzman, Evan S Shelby, Clarence E Smith, David Cole, Robert M Kessler & David H Zald


Psychopathy is a disorder that has typically been considered to result from a primary deficit in fear or empathy. Here the authors find that impulsive-antisocial psychopathic traits are correlated with hyper-reactivity of the dopaminergic reward system as measured with positron emission tomography and functional magnetic resonance imaging.



Dnmt1 and Dnmt3a maintain DNA methylation and regulate synaptic function in adult forebrain neurons pp423 - 430

Jian Feng, Yu Zhou, Susan L Campbell, Thuc Le, En Li, J David Sweatt, Alcino J Silva & Guoping Fan


In dividing cells, the epigenetic mechanism of DNA methylation is catalyzed by enzymes that maintain DNA methylation or act as a de novo methyltransferase. In this study, the authors find that DNA methyltransferases Dnmt1 and 3a have an active role in the maintenance of DNA methylation in postmitotic excitatory neurons. Results indicate that there is a redundancy between the two enzymes in neurons and that DNA methylation is essential for normal synaptic plasticity and memory formation.

See also: News and Views by Korzus

Presynaptic GABAA receptors enhance transmission and LTP induction at hippocampal mossy fiber synapses pp431 - 438

Arnaud Ruiz, Emilie Campanac, Ricardo S Scott, Dmitri A Rusakov & Dimitri M Kullmann


This study shows that tonically active, delta subunit–containing presynaptic GABAA receptors facilitate excitatory synaptic transmission at hippocampal mossy fiber synapses. Presynaptic GABAA receptors depolarize presynaptic boutons, enhance calcium entry evoked by action potentials and facilitate LTP induction in mossy fiber–CA3 synapses.

Diversity and wiring variability of olfactory local interneurons in the Drosophila antennal lobe pp439 - 449

Ya-Hui Chou, Maria L Spletter, Emre Yaksi, Jonathan C S Leong, Rachel I Wilson & Liqun Luo


Authors present a comprehensive genetic, anatomical and electrophysiological analysis of the local interneurons in the Drosophila antennal lobe. They find an unexpected degree of complexity and individual variation in this invertebrate neural circuit.

Loss of Arc renders the visual cortex impervious to the effects of sensory experience or deprivation pp450 - 457

Cortina L McCurry, Jason D Shepherd, Daniela Tropea, Kuan H Wang, Mark F Bear & Mriganka Sur


The immediate early gene Arc has been implicated in many forms of synaptic plasticity. This report finds that in mice lacking Arc, the visual cortex remains unmodified by deprivation or experience, suggesting that Arc expression is among the mechanisms that are critical for experience-dependent plasticity.

Control of sexual differentiation and behavior by the doublesex gene in Drosophila melanogaster pp458 - 466

Elizabeth J Rideout, Anthony J Dornan, Megan C Neville, Suzanne Eadie & Stephen F Goodwin


This study defines the roles of the doublesex gene in male and female flies' courtship circuitry and behaviors.

Central clock excites vasopressin neurons by waking osmosensory afferents during late sleep pp467 - 474

Eric Trudel & Charles W Bourque


Osmoregulated vasopressin release is facilitated during the late sleep period to prevent dehydration. This study finds that suprachiasmatic clock neurons modulate osmosensory synapses onto vasopressin neurons to enable such facilitation.

See also: News and Views by Colwell

Methylphenidate facilitates learning-induced amygdala plasticity pp475 - 481

Kay M Tye, Lynne D Tye, Jackson J Cone, Evelien F Hekkelman, Patricia H Janak & Antonello Bonci


The mechanisms by which methylphenidate (MPH or Ritalin) modifies behavioral performance are poorly understood. The authors show that MPH increased learning-induced strengthening of connections between the cortex and amygdala. This modulation was dependent on specific dopamine receptor subtypes.

Observational fear learning involves affective pain system and Cav1.2 Ca2+ channels in ACC pp482 - 488

Daejong Jeon, Sangwoo Kim, Mattu Chetana, Daewoong Jo, H Earl Ruley, Shih-Yao Lin, Dania Rabah, Jean-Pierre Kinet & Hee-Sup Shin


Primates can develop a conditioned fear response by witnessing other primates being subjected to adverse stimuli. Jeon et al. report that mice are capable of this form of observational fear conditioning and that the medial pain system underlies the neural circuits mediating socially acquired fear.

See also: News and Views by Grenier & Lüthi

Synaptic correlates of fear extinction in the amygdala pp489 - 494

Taiju Amano, Cagri T Unal & Denis Paré


The mechanisms underlying fear extinction remain unclear. Here, the authors show that extinction enhances basolateral amygdala inputs about conditioned stimuli to intercalated cells, resulting in the inhibition of fear output central amygdala neurons. These changes required medial prefrontal activity during extinction training, but, once induced, could be expressed without prefrontal inputs.

Intention and attention: different functional roles for LIPd and LIPv pp495 - 500

Yuqing Liu, Eric A Yttri & Lawrence H Snyder


Lateral intraparietal cortex (LIP) has been implicated in both attention and oculomotor control, but whether these functions are spatially overlapping remains unknown. Here the authors co-injected muscimol, to temporarily inactivate areas of LIP, and manganese, to enable MRI imaging of the inactivation site. They found that dorsal LIP is primarily an oculomotor planning area, whereas ventral LIP shows dissociable circuits for both attentional and oculomotor processes.

Resistance to forgetting associated with hippocampus-mediated reactivation during new learning pp501 - 506

Brice A Kuhl, Arpeet T Shah, Sarah DuBrow & Anthony D Wagner


The authors find that during the encoding of new memories, responses in the human hippocampus are predictive of the retention of memories for previously experienced, overlapping events. They report that this is accomplished by reactivating the neural representation of older memories as new memories are formed.

See also: News and Views by Fernández & Kroes

A central role for the lateral prefrontal cortex in goal-directed and stimulus-driven attention pp507 - 512

Christopher L Asplund, J Jay Todd, Andy P Snyder & René Marois


Attention can be driven by both stimulus- and goal-based processes. In the procedure used in this study, such 'bottom-up' and 'top-down' driven attentional processes appear to converge in the lateral prefrontal cortex.


Technical Report

Monitoring neural activity with bioluminescence during natural behavior pp513 - 520

Eva A Naumann, Adam R Kampff, David A Prober, Alexander F Schier & Florian Engert


The authors devised a method for detecting the bioluminescent Ca2+ sensor GFP-Aequorin in freely behaving zebrafish larvae. To demonstrate the efficacy of the technique, they targeted the sensor to a genetically specified population of hypothalamic neurons. The resulting neuroluminescence reveals patterns of neuronal activity that are associated with distinct swimming behaviors.