| 1. |
- Fransén, Erik, 1962-, et al.
(författare)
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Mechanism of graded persistent cellular activity of entorhinal cortex layer V neurons
- 2006
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Ingår i: Neuron. - : Elsevier BV. - 0896-6273 .- 1097-4199. ; 49:5, s. 735-746
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Tidskriftsartikel (refereegranskat)abstract
- Working memory is an emergent property of neuronal networks, but its cellular basis remains elusive. Recent data show that principal neurons of the entorhinal cortex display persistent firing at graded firing rates that can be shifted up or down in response to brief excitatory or inhibitory stimuli. Here, we present a model of a potential mechanism for graded firing. Our multicompartmental model provides stable plateau firing generated by a nonspecific calcium-sensitive cationic (CAN) current. Sustained firing is insensitive to small variations in Ca2+ concentration in a neutral zone. However, both high and low Ca2+ levels alter firing rates. Specifically, increases in persistent firing rate are triggered only during high levels of calcium, while decreases in rate occur in the presence of low levels of calcium. The model is consistent with detailed experimental observations and provides a mechanism for maintenance of memory-related activity in individual neurons.
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| 2. |
- Tahvildari, Babak, et al.
(författare)
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Switching between on and off states of persistent activity in lateral entorhinal layer III neurons
- 2007
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Ingår i: Hippocampus. - : Wiley. - 1050-9631 .- 1098-1063. ; 17:4, s. 257-263
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Tidskriftsartikel (refereegranskat)abstract
- Persistent neural spiking maintains information during a, working memory task when a stimulus is no longer present. During I retention, this activity needs to be stable to distractors. More importantly, when retention is no longer relevant, cessation of the activity is necessary to enable processing and retention of subsequent information. Here, by means of intracellular recording with sharp microelectrode in in vitro rat brain slices, we demonstrate that single principal layer III neurons of the lateral entorhinal cortex (EC) generate persistent spiking activity with a novel ability to reliably toggle between spiking activity and a silent state. Our data indicates that in the presence of muscarmic receptor activation, persistent activity following an excitatory input may be induced and that a subsequent excitatory input can terminate this activity and cause the neuron to return to a silent state. Moreover, application of inhibitory hyperpolarizing stimuli is neither able to decrease the frequency of the persistent activity nor terminate it. The persistent activity can also be initiated and terminated by synchronized synaptic stimuli of layer II/III of the perirhinal cortex. The neuronal ability to switch On and Off persistent activity may facilitate the concurrent representation of temporally segregated information arriving in the EC and being directed toward the hippocampus.
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