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We tested the hypothesis that different regions of lateral temporal cortex are specialized for processing different types of visual motion by studying the cortical responses to moving gratings and to humans and manipulable objects (tools and utensils) that were either stationary or moving with natural or artificially generated motions. Segregated responses to human and tool stimuli were observed in...
Kainate receptors (KARs) on CA1 pyramidal cells make no detectable contribution to EPSCs. We report that these receptors have a metabotropic function, as shown previously for CA1 interneurons. Brief kainate exposure caused long-lasting inhibition of a postspike potassium current (IsAHP) in CA1 pyramidal cells. The pharmacological profile was independent of AMPA receptors or the GluR5 subunit, indicating...
A unique feature of the olfactory bulb circuit is the long projection of the mitral cell lateral dendrites. Through dendrodendritic reciprocal synapses, these dendrites connect one olfactory glomerular module to hundreds of others; but the functional principles governing these extensive lateral interactions remain largely unknown. Here we report that the spatial extent of action potential propagation...
Here, we examine the synaptic function of the receptor protein tyrosine phosphatase (RPTP), Dlar, and an associated intracellular protein, Dliprin-α, at the Drosophila larval neuromuscular junction. We show that Dliprin-α and Dlar are required for normal synaptic morphology. We also find that synapse complexity is proportional to the amount of Dlar gene product, suggesting that Dlar activity determines...
Chemical synapses contain specialized pre- and postsynaptic structures that underlie rapid synaptic transmission and its modulation. Studies of postsynaptic organization have revealed a network of interacting proteins that enable rapid synaptic responses and their modulation. Recent genetic and electrophysiological studies on two active zone proteins—RIM and Munc13—reveal important roles in priming...
Current treatments for depression are inadequate for many individuals, and progress in understanding the neurobiology of depression is slow. Several promising hypotheses of depression and antidepressant action have been formulated recently. These hypotheses are based largely on dysregulation of the hypothalamic-pituitary-adrenal axis and hippocampus and implicate corticotropin-releasing factor, glucocorticoids,...
The functional roles of protein tyrosine phosphatases (PTPs) in the developed CNS have been enigmatic. Here we show that striatal enriched tyrosine phosphatase (STEP) is a component of the N-methyl-D-aspartate receptor (NMDAR) complex. Functionally, exogenous STEP depressed NMDAR single-channel activity in excised membrane patches. STEP also depressed NMDAR-mediated synaptic currents whereas inhibiting...
AMPA receptor (AMPAR) trafficking is crucial for synaptic plasticity that may be important for learning and memory. NSF and PICK1 bind the AMPAR GluR2 subunit and are involved in trafficking of AMPARs. Here, we show that GluR2, PICK1, NSF, and α-/β-SNAPs form a complex in the presence of ATPγS. Similar to SNARE complex disassembly, NSF ATPase activity disrupts PICK1-GluR2 interactions in this complex...
Dendrodendritic inhibition between mitral and granule cells in the olfactory bulb is thought to play an important role in olfactory discrimination. In this issue of Neuron, Xiong and Chen (2002) explore the propagation of action potentials along the secondary dendrites of mitral cells and their modulation by dendrodendritic inhibition.
We measured brain activity during mental rotation and object recognition with objects rotated around three different axes. Activity in the superior parietal lobe (SPL) increased proportionally to viewpoint disparity during mental rotation, but not during object recognition. In contrast, the fusiform gyrus was preferentially recruited in a viewpoint-dependent manner in recognition as compared to mental...
In this issue of Neuron, Beauchamp and colleagues (2002) differentiated brain regions in humans that are selectively responsive to viewing motion: (1) of humans, (2) of tools/utensils, and (3) in general. Active regions were the superior temporal sulcus, middle temporal gyrus, and MT/V5, respectively. This study provides impetus for future work in motion perception and its relationship to apraxia.
In the Drosophila circadian clock, daily cycles in the RNA levels of dclock (dClk) are antiphase to those of period (per). We altered the timing/levels of dClk expression by generating transgenic flies whereby per circadian regulatory sequences were used to drive rhythmic transcription of dClk. The results indicate that posttranscriptional mechanisms make substantial contributions to the temporal...
Drosophila phototransduction results in the opening of two classes of cation channels, composed of the channel subunits transient receptor potential (TRP), TRP-like (TRPL), and TRPγ. Here, we report that one of these subunits, TRPL, is translocated back and forth between the signaling membrane and an intracellular compartment by a light-regulated mechanism. A high level of rhabdomeral TRPL, characteristic...
Interaction with the multi-PDZ protein GRIP is required for the synaptic targeting of AMPA receptors, but the underlying mechanism is unknown. We show that GRIP binds to the liprin-α/SYD2 family of proteins that interact with LAR receptor protein tyrosine phosphatases (LAR-RPTPs) and that are implicated in presynaptic development. In neurons, liprin-α and LAR-RPTP are enriched at synapses and coimmunoprecipitate...
We assessed the human brain network for sound-motion processing using the same virtual stimulus in three independent functional imaging experiments. All experiments show a bilateral posterior network of activation, including planum temporale (PT) and parieto-temporal operculum (PTO). This was demonstrated in contrasts between sound movement and two control conditions: externalized stationary stimuli...
Papers by Sokolov et al. (2002) and Bähner et al. (2002), in this issue of Neuron, describe how massive and rapid translocation of specific elements of the phototransduction cascades in different phyla, namely, the G protein (transducin) in vertebrate rods and light-sensitive TRPL channels in the microvillar rhabdomeres of Drosophila, contribute to photoreceptor adaptation.
We report a new cellular mechanism of rod photoreceptor adaptation in vivo, which is triggered by daylight levels of illumination. The mechanism involves a massive light-dependent translocation of the photoreceptor-specific G protein, transducin, between the functional compartments of rods. To characterize the mechanism, we developed a novel technique that combines serial tangential cryodissection...
Two papers in this issue of Neuron add a new dimension to our understanding of liprin and LAR RPTP function during synapse formation. Kaufmann et al. (2002) present evidence that Dliprin-α interacts with Dlar to regulate presynaptic morphogenesis of the Drosophila neuromuscular junction. Wyszynski et al. (2002) demonstrate that mammalian liprin-α1 forms a complex with the PDZ protein GRIP and LAR...
During central nervous system development, neurons are often born in a precise temporal sequence. Basic helix-loop-helix (bHLH) transcription factors are required for the development of specific subpopulations of neurons, but how they contribute to their ordered genesis is unclear. We show that the ability of bHLH factors to regulate the development of distinct neuronal subtypes in the Xenopus retina...
Complex learned motor sequences can be composed of a combination of a small number of elementary actions. To investigate how the brain represents such sequences, we devised an oculomotor sequence task in which the monkey had to choose the target solely by the sequential context, not by the current stimulus combination. We found that many neurons in the supplementary eye field (SEF) became active with...
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