Barkai, E., & Hasselmo, M. E. (1994). Modulation of the input/output function of rat piriform cortex pyramidal cells. J Neurophys, 72, 644--658.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....rate or a cessation of firing at later stages of a sustained injection. This spike frequency adaptation can be mostly suppressed by local application of norepinephrine or acetylcholine (Sherman and Koch, 1986; Steriade and Llinas, 1988) which block a slow calcium dependent potassium current. Barkai and Hasselmo (1994) describe the adaptation characteristics of representative layer II pyramidal cells from piriform cortex, provide a measure for classifying these cells as showing either strong or weak adaptation, and develop a biophysical model to demonstrate the adaptation characteristics of both types of cells. ....

Barkai, E. and Hasselmo, M. E. (1994). Modulation of the input/output function of rat piriform cortex pyramidal cells. Journal of Neurophysiology, 72:644--658.

....in the face of conflicting inputs can be very useful, and it seems that nature has found a way to create such units where needed. The bad news for more abstract connectionist models of cognitive phenomena is that, as has been noted in other studies of the effects of modulatory neurotransmitters (Barkai Hasselmo, 1994; Barkai et al. 1994) real neurons sometimes have response properties which cannot adequately be captured by units with simple sigmoid activation functions. This adds to the complication of determining how models based on such units relate to the activity of the brain. ....

....inputs can be very useful, and it seems that nature has found a way to create such units where needed. The bad news for more abstract connectionist models of cognitive phenomena is that, as has been noted in other studies of the effects of modulatory neurotransmitters (Barkai Hasselmo, 1994; Barkai et al. 1994), real neurons sometimes have response properties which cannot adequately be captured by units with simple sigmoid activation functions. This adds to the complication of determining how models based on such units relate to the activity of the brain. ....

Barkai, E., & Hasselmo, M. E. (1994). Modulation of the input/output function of rat piriform cortex pyramidal cells. Journal of Neurophysiology, 72(2), 644658.

....of activity within the full network to be related to the physiological characteristics of individual neurons. In place of sigmoid input output functions, the network utilized threshold linear neurons with adaptation, which more closely resemble the input output function of real cortical neurons (Barkai and Hasselmo, 1994). Total network activity was kept bounded by feedback from inhibitory interneurons and adaptation due to intracellular calcium concentration. Separate variables represent pyramidal cell membrane potential a, intracellular calcium concentration c, and the membrane potential of inhibitory ....

....H ik = inhibitory synapses from interneurons to pyramidal cells, H kl = inhibitory synapses between interneurons. These equations can account for the spike frequency adaptation and afterhyperpolarization which can be observed during intracellular recording from cortical pyramidal cells (Barkai and Hasselmo, 1994; Hasselmo et al. 1995a) Figure 1. A. Response of single simulated neuron to current injection, showing adaptation and afterhyperpolarization due to simplified representation of calcium dependent potassium current. Output of this model is a continuous variable proportional to how much membrane ....

Barkai E, Hasselmo ME (1994) Modulation of the input/output function of rat piriform cortex pyramidal cells. J. Neurophysiol. 72: 644-658.

....generation of simulated action potentials. They also include a noninactivating voltagedependent potassium current (I K GammaM ) a calciumdependent potassium current (I K GammaAHP ) and a high threshold voltage activated calcium current (I Ca ) similar to those in other pyramidal cell models (Barkai and Hasselmo, 1994; Traub et al. 1991; Pinsky and Rinzel, 1994) The standard voltageindependent leak currents (I L GammaS and I L GammaD ) are included where the current in the soma partially reflects impalement damage. The kinetics of the model conductances were initialized with parameters taken from a model of ....

Barkai, E. and Hasselmo, M. E. (1994). Modulation of the input/output function of rat piriform cortex pyramidal cells. Journal of Neurophysiology, 72:644--658.

....2 . Equation 3.2 reduces to: #a i # # = H i # , 3.3) if H i # #. 3.4) The condition in equation 3.4 is true when the a max state is far from the saturating regime of the equation, that is, when the mean activity #a i # still increases linearly with synaptic input. This is true (Barkai Hasselmo, 1994) over the range of firing frequencies observed in vivo (O Keefe Recce, 1993; Skaggs et al. 1996) Changes in GABA B Modulation 877 Now consider a simplification of the neural network shown in Figure 1 in which the interneuron is replaced by linear inhibition: a 2 = #a 2 kA A bias ....

Barkai, E., & Hasselmo, M. E. (1994). Modulation of the input/output function of rat piriform cortex pyramidal cells. J Neurophys, 72, 644--658.

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Barkai, E. and Hasselmo, M.E. (1994) Modulation of the input/output function of rat piriform cortex pyramidal cells J. Neurophysiol. 72, 644--658

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