Research articles

Using high-resolution fMRI in macaque monkeys, the authors demonstrate the existence of a topographic representation for temporal sound properties, which runs from dorsomedial to the ventralateral in the inferior colliculus. This is in addition to a previously reported representation of sound spectral properties (also found here), running approximately perpendicular to the temporal map.

In addition to the morphological difference, inner hair cell (IHC) synapses do not have the full complement of neuronal SNARE proteins found in other types of synapses. Here, Nouvian et al. provide a series of empirical evidence that shows that exocytosis in IHCs occurs independently of neuronal SNARE proteins.

This paper reports an in vivo imaging method that monitors real-time synaptic transmission simultaneously at many release sites with quantal resolution. The authors demonstrate the utility of this technique by using it to study the glutamatergic system of Drosophila larval NMJ.

The authors report that the chloride channel CLC-3 colocalizes with the vesicular GABA transporter VGAT in the CA1 region of the hippocampus, where it affected Cl⁻-induced acidification of synaptic vesicles. Clcn3^−/− animals showed a decrement in inhibitory transmission, suggesting a decrease in neurotransmitter loading of synaptic vesicles.

The authors expose Xenopus tadpoles to the convulsant PTZ. After an initial PTZ exposure, seizure onset times were delayed in response to a second PTZ exposure. This protective effect resulted from conversion of putrescine into GABA, which in turn activated GABA_B receptors presynaptically and altered the balance of inhibition to excitation.

Individual tailored health interventions can be more effective than generic interventions in eliciting behavior change. Here, the authors find that increases in activations in self-related processing regions (including dorsomedial prefrontal cortex) predicted smoking cessation during a follow-up interval.

The authors find that hyperpolarization-activated cyclic nucleotide–gated 1 (HCN1) channel subunits are localized to the active zone of asymmetric synaptic terminals targeting mouse entorhinal cortical layer III pyramidal neurons. The presynaptic HCN channels inhibit synaptic glutamate release by suppressing the activity of low-threshold voltage-gated T-type (Ca_V3.2) calcium channels.

The authors identify brain RNA targets for TDP-43, a RNA binding protein linked to ALS. RNAs derived from genes with very long introns were more affected by TDP-43 levels. TDP-43 also auto-regulated its own synthesis, partly by binding and enhancing the splicing of an intron in its 3′ UTR

Class I major histocompatibility complex (MHCI) is known to modulate activity-dependent synaptic remodeling in the visual system and to regulate synaptic plasticity in the hippocampus. Here, the authors show that MHCI negatively regulates the density and function of cortical synapses during their initial establishment.

The authors find that the principal hippocampal neurons consist of distinct subpopulations that show distinct neurogenesis and synaptogenesis time windows and that these neurons interconnect selectively at dentate gyrus–to-CA3 and CA3-to-CA1 synapses.

TDP-43 is a RNA-binding protein that forms inclusion bodies in ALS. The authors show that TDP-43 preferentially binds long clusters of UG-rich sequences and that TDP-43 binding on pre-mRNAs influences alternative splicing. Many alternative mRNA isoforms regulated by TDP-43 encode proteins that regulate neuronal development or are implicated in neurological diseases.

Using a pharmacogenetic method of Daun02 to selectively inhibit activated neurons, Bossert et al. find that neurons in the ventral medial prefrontal cortex mediate context-induced drug relapse in a rat model of drug reinstatement.

Cocaine is known to influence the synaptic plasticity of dopaminergic neurons in the ventral tegmental area (VTA). Contrary to the earlier studies, Mameli et al. find that cocaine treatment can reduce synaptic NMDA receptor currents while increasing the synaptic insertion of calcium-permeable AMPA receptors. Cocaine treatment also reversed the rule of spiking timing–dependent plasticity in the VTA.

The authors report that adolescent nicotine exposure in rats induces lasting attentional disturbances and reduces mGluR2 function in the PFC. Restoring mGluR2 activity rescued attention specifically.

The authors describe a technique for delivering DNA vectors through a patch-pipette following characterization of the neuron by whole-cell recording. They demonstrate the utility of the approach by mapping the synaptic and anatomical receptive fields of several visual cortical neurons.

According to reinforcement learning theory, reward expectation reflects an integration of past rewards over a fixed time scale. Here the authors extract signals about reward memory from neurons in the prefrontal, cingulate and parietal cortex, finding a wide range of time constants across the neuronal population, with a power-law distribution.

In Drosophila, R7 and R8 photoreceptors, which detect different wavelengths, form synapses in distinct medulla layers. The authors report that Golden Goal and Flamingo, two cell-surface proteins involved in photoreceptor targeting, functionally interact in R8 cells and that their interaction specifies synaptic-layer selection of photoreceptors.

Westerlund and colleagues show that c-Jun N-terminal protein kinase 1 (JNK1), via phosphorylation of SCG10/Stathmin-2, acts as a negative regulator of the rate of neuronal migration and transition through the multipolar stage during cortical development in rodents.

Larsen et al. find that presynaptic NMDA receptors at neocortical synapses are heteromeric receptors containing the developmentally expressed NR3A subunit. Their data also indicate that NR3A-containing presynaptic NMDARs mediate tonic presynaptic activity, synaptic transmission and spike timing–dependent plasticity.

Although the olfactory receptor neurons converging onto the same glomeruli in the olfactory bulb are known, evidence for an olfactory map at cortical level is lacking. The current study finds that mitral cells that are born later during embryogenesis preferentially project to the olfactory tubercles as the late-born mitral cells tangentially migrate further on the axons of earlier born cells, forming an organization of neuronal projection into the olfactory cortex based on the timing of cell birth.