Alterations in frequency coding and activity dependence of excitability in cultured neurons of Drosophila memory mutants.
نویسندگان
چکیده
Mutants of the Drosophila dunce (dnc) and rutabaga (rut) genes, which encode a cAMP-specific phosphodiesterase and a calcium/calmodulin-responsive adenylyl cyclase, respectively, are deficient in short-term memory. Altered synaptic plasticity has been demonstrated at neuromuscular junctions in these mutants, but little is known about how their central neurons are affected. We examined this problem by using the "giant" neuron culture, which offers a unique opportunity to analyze mutational effects on neuronal activity and the underlying ionic currents in Drosophila. On the basis of instantaneous frequency and first latency of spikes evoked by current steps, four categories of firing patterns (tonic, adaptive, delayed, and interrupted) were identified in wild-type neurons, revealing interesting parallels to those commonly observed in vertebrate CNS neurons. The distinct firing patterns were correlated with expression of different ratios of 4-aminopyridine- and tetraethylammonium-sensitive K+ currents. Subsets of dnc and rut neurons displayed abnormal spontaneous spikes and altered firing patterns. Altered frequency coding in mutant neurons was demonstrated further by using stimulation protocols involving conditioning with previous activity. Abnormal spike activity and reduced K+ current remained in double-mutant neurons, suggesting that the opposite effects on cAMP metabolism by dnc and rut do not counterbalance the mutual functional defects. The aberrant spontaneous activity and altered frequency coding in different stimulus paradigms may present problems in the stability and reliability of neural circuits for information processing during certain behavioral tasks, raising the possibility of modulation in neuronal excitability as a cellular mechanism underlying learning and memory.
منابع مشابه
Antibiotic Supplements Affect Electrophysiological Properties and Excitability of Rat Hippocampal Pyramidal Neurons in Primary Culture
Introduction: Antibiotic supplements are regularly used in neuronal culture media to control contamination however, they can interfere with the neuronal excitability and affect electrophysiological properties. Therefore, in this study, the effect of penicillin/streptomycin supplements on the spontaneous electrophysiological activity of hippocampal pyramidal neurons was examined. Methods: Electr...
متن کاملDistinct roles of CaMKII and PKA in regulation of firing patterns and K(+) currents in Drosophila neurons.
The Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and the cAMP-dependent protein kinase A (PKA) cascades have been implicated in neural mechanisms underlying learning and memory as supported by mutational analyses of the two enzymes in Drosophila. While there is mounting evidence for their roles in synaptic plasticity, less attention has been directed toward their regulation of neurona...
متن کاملAuxiliary Hyperkinetic beta subunit of K+ channels: regulation of firing properties and K+ currents in Drosophila neurons.
Auxiliary Hyperkinetic beta subunit of K+ channels: regulation of firing properties and K+ currents in Drosophila neurons. Molecular analysis and heterologous expression have shown that K+ channel beta subunits regulate the properties of the pore-forming alpha subunits, although how they influence neuronal K+ currents and excitability remains to be explored. We studied cultured Drosophila "gian...
متن کاملPeroxisome Proliferator-activated Receptor (PPAR)-γ Modifies Aβ Neurotoxin-induced Electrophysiological Alterations in Rat Primary Cultured Hippocampal Neurons
Alzheimer’s disease (AD) is undoubtedly one of the serious and growing public health challenges in the world today. There is an unmet need for new and effective preventative and therapeutic treatment approaches for AD, particularly at early stages of the disease. However, the underlying mechanism against Aβ-induced electrophysiological alteration in cultured hippocampal pyramidal neurons is st...
متن کاملPeroxisome Proliferator-activated Receptor (PPAR)-γ Modifies Aβ Neurotoxin-induced Electrophysiological Alterations in Rat Primary Cultured Hippocampal Neurons
Alzheimer’s disease (AD) is undoubtedly one of the serious and growing public health challenges in the world today. There is an unmet need for new and effective preventative and therapeutic treatment approaches for AD, particularly at early stages of the disease. However, the underlying mechanism against Aβ-induced electrophysiological alteration in cultured hippocampal pyramidal neurons is st...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The Journal of neuroscience : the official journal of the Society for Neuroscience
دوره 17 6 شماره
صفحات -
تاریخ انتشار 1997