Brief Communications in 2009

This study implicates the proteosome degradation machinery in controlling axon guidance by showing that the deubiquiting enzyme USP33 is essential for controlling Slit/Robo-mediated commissural axonal guidance.

Here, the authors describe the presynaptic mechanism for the induction of cortico-amygdala LTP that involves presynaptic L-type voltage-dependent Ca²⁺ channels in the lateral amygdala.

When learning to use a novel tool, autistic children build a stronger link between their movements and proprioceptive feedback than typically developing children. Their greater reliance on proprioception correlates with the severity of social and impairment deficits.

Current techniques are insufficient for resolving the contribution of single photoreceptors to the responses of visually responsive neurons in the brain. Here, the authors employ a new technique, which utilizes adaptive optics, to show that LGN neurons respond reliably to the stimulation of a single cone.

Mutations in LRRK2 can cause Parkinson's disease. The authors create a transgenic mouse model of LRRK2 that recapitulates several cardinal features of the disease.

Synaptic plasticity at the cerebellar parallel fiber–Purkinje cell is mediated by calcium/calmodulin kinase II. In a knockout mouse line lacking the beta subunit of CaMKII, the authors show a bidirectional inversion of synaptic plasticity accompanying movement disorders and impaired motor learning.

Potassium-chloride co-transporter 2 (KCC2) activity is known to be attenuated by neural injury. Hershfinkel et al. show that KCC2 activity is inhibited by intracellular free zinc, a component of neuronal injury signaling pathways. Oxygen-glucose deprivation results in attenuation of KCC2 activity that is reversible by intracellular zinc chelation.

Lledo and colleagues report that one subset of excitatory synapses onto adult-born granule cells in the mouse olfactory bulb shows long-term potentiation. This property, however, fades as the newborn neurons mature.

Using two photon–guided stimulation, the authors demonstrate spike timing–dependent plasticity of cortical feedback inputs to olfactory bulb granule cells.

Much work has been devoted to the elucidation of pain signaling, whereas the transduction of pleasant touch has garnered less attention. In this study, the authors present data suggesting that pleasant touch is mediated by a particular dedicated type of peripheral nerve fibers, the low-threshold, unmyelinated mechanoreceptive C-tactile afferents.

Here, the authors show that scratching the cutaneous receptive field of primate spinothalamic neurons produces inhibition during histamine-evoked itchiness, but not during spontaneous activity or activity evoked by pain. This suggests that the inhibition of itch by scratching is state-dependent in the spinal cord.

At the calyx of Held nerve terminal, Wu and Paradiso show that small hyperpolarizations or depolarizations can travel back up the axon and influence the threshold for action potential initiation.

This study finds that playing an action video game results in improvements in visual contrast sensitivity. These improvements do not happen for an equivalent group who played a non-action video game.

Axon degeneration is an active process. Miller and colleagues show in fly and mouse models that axon degeneration requires the kinase DLK and its downstream target JNK to proceed.

The striatum contains two distinct types of GABAergic neurons, striatonigral and striatopallidal cells. Durieux and colleagues genetically ablated the striatopallidal population in mice, uncovering specific roles for these neurons in the control of locomotion and the response to the addictive drug amphetamine.

To understand how monocular eyelid closure and retinal inactivation can affect cortical ocular dominance, Linden et al. examined the firing activity of the dorsal lateral geniculate nucleus. They report that the firing pattern, but not the firing rate, is differentially affected by manipulations of retinal activity.

The glucocorticoid receptor is a transcription factor that mediates adaptation to stress. The authors show that selective glucocorticoid receptor deletion in postsynaptic dopamine receptor 1a–expressing neurons, but not in presynaptic neurons that release dopamine, decreases the motivation of mice to self-administer cocaine.

Animal studies show that fear memories can change when recalled, a process known as reconsolidation. Here the authors find that administration of propranolol prior to memory reactivation erases the expression of fear memory and prevents its return.

Many population coding models of reinforcement learning assign a single global reward signal to the entire population. As the population size increases, however, this reward signal is less and less related to the performance of a single neuron, slowing down learning. This computational modeling study shows that an additional population response term modifying synaptic plasticity speeds up learning.

One of the ongoing debates in memory research is whether the fidelity of remote memory, as it matures, requires the hippocampus. Using a contextual discrimination procedure that can test memory precision over time, this paper reveals that the hippocampus is not essential in the precise maintenance of remote memory.