Firing patterns

It is easy to speculate that in an active neuron with a rapid firing pattern, the continued release of a peptide may eventually lead to depletion of the peptide occurring. This has been shown in the peripheral nervous system. If this also happens in the CNS it would provide a mechanism whereby the release and resultant receptor effects of a transmitter no longer match the firing pattern and demands of the neuron and so could contribute to long-term adaptations of neurons by a reduction in the time over which a peptide is effective. 

The excessive electrical discharges can spread to other neurons, either adjacent ones or distant ones connected by fiber tracts. The seizure thus spreads to other areas of the brain, recruiting them into the uncontrolled firing pattern. The neurons involved may not be abnormal themselves, but are diverted from their normal functioning to participate in the wildly excessive discharges. The degree of spread and the location of brain areas involved determine the clinical manifestations of the seizure. 

Kitai S. T., Shepard P. D., Callaway J. C., Scroggs R. (1999). Afferent modulation of dopamine neuron firing patterns. Curr. Opin. Neurobiol. 9(6), 690-7. 

Nunemaker CS, De Fazio RA, Moenter SM (2002) Estradiol-sensitive afferents modulate long-term episodic firing patterns of GnRH neurons. Endocrinology 143 2284-2292... 

Wang, R. Y., and Aghajanian, G. K. (1982) Correlative firing patterns of serotonergic neurons in rat dorsal raphe nucleus. J. Neurosci., 2 11-16. 

Indirect mechanisms Nicotine has indirect effects on monoamine systems. A considerable amount of research has examined the relationships between nicotine and dopamine activity in the brain, in light of dopamine s role in reinforcement and nicotine s addictive properties. Nicotine increases dopamine turnover in the striatum and cerebral cortex (Clarke and Reuben 1996 Tani et al. 1997 Nanri et al. 1998). It also increases burst activity in dopamine neurons of the ventral tegmental area (VTA), a primary source of dopamine to the forebrain (Nisell et al. 1995 Fisher et al. 1998). Such a firing pattern in the VTA is associated with processes of reinforcement, learning, and cognitive activity. Nicotine actions on dopaminergic neurons occur at both somatodendritic sites and synaptic terminals. Further, both systemic nicotine and direct administration into the VTA increase dopamine release in the nucleus ac-... 

Luetje CW, Patrick J (1991) Both alpha- and beta-subunits contribute to the agonist sensitivity of neuronal nicotinic acetylchohne receptors. J Neurosci 11 837-845 MameU-EngvaU M, Evrard A, Pons S, Maskos U, Svensson TH, Changeux JP, Faure P (2006) Hierarchical control of dopamine neuron-firing patterns by nicotinic receptors. Neuron 50 911-921 Mansvelder HD, McGehee DS (2000) Long-term potentiation of excitatory inputs to brain reward areas by nicotine. Neuron 27 349-357... 

The organization of the olfactory bulb during the first 2 postnatal weeks may be affected by specific olfactory experiences. Early experience may be incorporated into the firing pattern of olfactoiy neurons with the result that the mature brain responds in a particular, conditioned way to the now-familiar odor. Such response changes of the mammalian brain to naturally occurring odors as a consequence of specific early experience may be an important component of individual variation (Coopersmith and Leon, 1986). 

A possible link between the movement of the eyes (which is real) and the hallucinated dream movements (which are fictive) is provided by the PGO system. This is because the neuronal firing patterns associated with each PGO wave encode (at least) the direction of the eye movements and provide that encoded information to (at least) the visual thalamus and visual cortex. This means that in the absence of real sensory input from the eyes, feed forward information about the direction of the (also fictive) gaze is provided to the upper brain, which could (and we think almost certainly must) use it in the elaboration of the convincing visuomotor illusion that is dreaming. 

The extracellular microelectrode recording technique developed by David Hubei for his epochal studies of the cat visual system and further perfected by Eduard Evarts for his pioneering work on the cat motor system was easily applied to exploring the brain stem. There were two major obstacles that needed to be overcome to guarantee success, however. The first was movement not only was head movement itself a problem, but body movement also had to be limited because the targets were deep and located on the major axis of lateral and vertical head-on-neck movement. The second problem was identification of the neurons of interest. At the onset, no one knew that the modulatory elements would identify themselves both by their distinctive spike-to-spike firing pattern, but also—and this is the main point of the discovery—by their dramatic state dependent alterations of firing propensity. 

The tectorial membrane rests at the top of the organ of Corti, and the basilar membrane forms the base. Two types of hair cells are found along the basilar membrane. There are three rows of outer hair cells and one row of inner hair cells. The outer hair cells form part of the mechanical system of the cochlear partition, while the inner hair cells provide transduction from mechanical motion into neural firing patterns. There are about 30,000 nerve fibers in the human ear. The vast majority are afferent fibers that conduct the inner hair cell neural pulses towards the brain approximately 20 fibers are connected to each of the 1,500 inner hair cells. Approximately 1,800 efferent fibers conduct neural pulses from the brain to the outer hair cells [Pickles, 1988],... 

Macica CM, von Hehn CA, Wang LY et al (2003) Modulation of the kv3.1b potassium channel isoform adjusts the fidelity of the firing pattern of auditory neurons. J Neurosci 23 1133 11 Majewski H, Iannazzo L (1998) Protein kinase C a physiological mediator of enhanced transmitter output. Prog Neurobiol 55 463-75... 

All the information the fly needs for encoding quality, intensity and temporal variations of odors is present in the firing patterns of ORNs. We argue that, in Drosophila, all three features are encoded in the activity across a limited number of ORN classes (n 40) and is time dependent. Moreover, information about most odors is probably concentrated in a small subset of ORN classes. Because... 

A recent theoretical study has suggested that persistent activity in the PFG is considered to be an attractor state, in that relatively small amounts of variation in this state lead it back to the same state. This idea has been examined in detail theoretically, especially by Amit, who described persistent activity in terms of dynamical attractors (Amit and Brunei, 1997 Rolls et al., 2008). The spontaneous state and stimulus-selective memory states are assumed to represent multiple attractors, such that a memory state can be switched on or off by transient inputs. This formulation is plausible, insomuch as stimulus-selective persistent firing patterns are dynamically stable in time. These properties of attractors result from interactions in neuronal circuits. Neural synchrony is a general mechanism for dynamically linking together cells coding task-relevant information (Salmas and Sejnowski, 2001). The dynamics of neuronal activities and the representations they reflect are two sides of a coin. 

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