All events, 2008

TRP channels, what are they and why are they important

Lecture
Date:
Tuesday, January 8, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Prof. Baruch Minke
|
Hebrew University, Jeruslaem

TRP channels constitute a large and diverse family of proteins that are expressed in many tissues and cell types. The TRP superfamily is conserved throughout evolution from nematodes to humans. The name TRP is derived from a spontaneously occurring Drosophila mutant lacking TRP that responded to a continuous light with a Transient Receptor Potential (therefore, it was designated TRP by Minke). The Drosophila TRP and TRP-like (TRPL) channels, which are activated by the inositol lipid signaling cascade, were used later on to isolate the first mammalian TRP homologues. TRP channels mediate responses to light, nerve growth factors, pheromones, olfaction, taste, mechanical, temperature, pH, osmolarity, vasorelaxation of blood vessels, metabolic stress and pain. Furthermore, mutations in members of the TRP family are responsible for several diseases. Although a great deal is known today about members of the mammalian TRP channels, the exact physiological function and gating mechanisms of most channels are still elusive. Removal of divalent open channel block by depolarization plays a critical role in learning and memory, which is mediated by the N-methyl-D-aspartate (NMDA) channel. TRP channels also exhibit open channel block, but the physiological mechanism of its removal is still unknown. We found that lipids produced by phospholipase C (PLC) and hypoosmotic solutions remove divalent open channel block from the Drosophila TRPL channels without depolarization. Application of lipids increased single channel current and caused impermeable cation influx. The tarantula peptide GsMTx-4 specifically blocks a range of stretch-activated channels, but not by specific interaction with the channel proteins themselves but rather by modification of the channel-lipid boundary. The GsMTx-4 toxin blocked the lipids effect on TRPL channels. We found remarkable commonality between the effects of lipids on the Drosophila TRPL and the mammalian NMDA channels. We suggest a new lipid-dependent mechanism to alleviate open channel block, which operates under physiological conditions, in synergism with depolarization. The profound effect of lipids modulation allows cross talk between channel activity and lipid-producing pathways. Joint work with Moshe Parnas, Ben Katz & Shaya Lev

"A hierarchy of temporal receptive windows

Lecture
Date:
Tuesday, January 1, 2008
Hour: 12:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Dr. Uri Hasson
|
New York University

Real-world events unfold at different time scales, and therefore cognitive and neuronal processes must likewise occur at different time scales. In the talk I will present a novel procedure that identifies brain regions responsive to the preceding sequence of events (past time) over different time scales. The fMRI activity was measured while observers viewed silent films presented forward, backward, or piecewise-scrambled in time. The results demonstrate that responses in different brain areas are affected by information that has been accumulated over different time scales, with a hierarchy of temporal receptive windows spanning from short (~4 s) to intermediate (~12 s) and long (~ 36 s). Thus, although we adopted an open-ended experimental protocol (free viewing of complex stimuli), we found that parametric manipulation of the temporal structure of a complex movie sequence produced lawful changes in cortical activity across different brain regions. In addition to the reliable cortical response patterns, I will also show that films exerted considerable control over the subjects' behavior (i.e., eye movements or galvanic skin responses). Finally, I will present few applications of this method for studying the neuronal correlates of complex human behaviors under more natural settings.

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All events, 2008

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All events, 2008

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All events, 2008

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