Brief Communications in 2011

The authors report that Rhes, a striatal-specific protein, activates mTOR. Rhes-depleted mice showed reduced dyskinesia, but maintained motor improvement following L-DOPA treatment.

The authors conduct direct measurements of parvalbumin concentration and paired recordings in rodent hippocampus and cerebellum and show that parvalbumin affects synaptic dynamics, exerting Ca²⁺-buffering effects only when expressed at high levels.

A1 adenosine receptor is antagonized by caffeine and is highly expressed in the CA2 layer of rodent hippocampus. This study now shows that caffeine can induce CA2 synaptic potentiation in a dosage-dependent manner.

The authors report that the two main types of adult-born neurons in the mouse olfactory bulb show experience-dependent plasticity long after maturation and integration into the network.

Reversal learning requires cognitive flexibility and is mediated by multiple brain regions, including the prefrontal cortex and the dorsal striatum. This study examines how environmental factors such as stress can affect prefrontal cortex–dorsal striatum interactions and reversal learning.

Deficits in prefrontal cholinergic function have been implicated in cognitive impairment in many neuropsychiatric diseases. Here, the authors report that monkeys with lesions of cholinergic input to prefrontal cortex were impaired on a spatial working memory task, but not on other tests of cognitive function that also require intact prefrontal cortex.

In this behavioral study, the authors demonstrate how increased attention can sometimes lead to lower subject confidence, leading subjects to become more conservative in making decisions during a visual perception task.

The authors generated knock-in mice of the AMPAR auxiliary subunit TARP that lack the C-terminal PDZ ligand. They found that synaptic transmission and AMPAR were reduced without changes in extrasynaptic AMPAR expression, but LTP was unaltered.

Using two-photon microscopy in mice, the authors find that the number of cortical spines increases in adolescent mice while they are awake and decreases while they are asleep.

Maturation of adult-born neurons in the dentate gyrus is known to require GABAergic input. Here the authors show that a subtype of interneurons, namely neurogliaform cells, acts as the primary source of GABA for newborn neurons in mouse dentate gyrus.

Using hemisphere-specific optogenetic activation of hippocampal fibers, this study finds that the magnitude of long-term potentiation in CA1 neurons depends on whether afferents originate in left or right CA3.

This study shows that lesioning a rat's amygdala affects only familiarity-based recognition, having no effect on recollection-based recognition, and further dissociates the role of medial temporal lobe structures mediating recognition memory.

The authors report the existence of a bilateral parieto-frontal network in humans whose hemispheric lateralization predicts the degree of specialization of the right hemisphere for visuospatial attention. This specialization is associated with an unbalanced speed of visuospatial processing between the two hemispheres.

Using direct recordings in monkeys, the authors find that attention spreads to elements when gestalt cues indicate that it is part of an attended object, even when these elements themselves are outside of the focus of attention. This finding supports object-based attentional theories.

The authors employ the computational learning approach that is widely used in the striatum to examine the contributions of the amygdala, and find that these two structures have complementary roles in aversive learning.

CREB-mediated transcription is known to be important for ocular dominance plasticity (ODP). Expression of the mircoRNA miR-132 is under CREB control, and this study finds that miR-132 directly regulates ODP.

This study identifies a subset of microRNAs whose expression is differentially regulated by visual experience and finds that inhibition of one of the miRNAs, miR-132, in the mouse visual cortex impairs ocular dominance plasticity.

Recording from neurosurgical patients undergoing epilepsy monitoring, the authors find specific responses to pictures of animals in the right amygdala.

Homeostatic plasticity is triggered by changes in somatic Ca²⁺ levels and the gamma secretase component presenilin 1 (PS1) is known to regulate intracellular Ca²⁺. Pratt et al. find that homeostatic synaptic plasticity is impaired in neurons lacking PS1 or expressing an Alzheimer's disease–linked PS1 mutation because of a deficit in kinase signaling unrelated to Ca²⁺ levels or gamma secretase activity.

Fear-extinction learning increases the expression of the brain-specific microRNA miR-128b. The authors find that this increase in miR-128b expression disrupts the stability of plasticity-related target genes and directly regulates fear-extinction memory. Increased miR-128b activity could facilitate the transition from retrieval of the original fear memory to the formation of a new fear-extinction memory.