Low-threshold Ca2+-associated bursts are rare events in the LGN of the awake behaving monkey
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Type = Article
Cím:
Low-threshold Ca2+-associated bursts are rare events in the LGN of the awake behaving monkey
Létrehozó:
Ruiz, O.
Royal, D.
Sáry, Gyula
Kiadó:
American Physiological Society
Dátum:
2006
Téma:
RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry / idegkórtan, neurológia, pszichiátria
Tartalmi leírás:
It has been proposed that low-threshold Ca2+ (LT)-associated bursts in the
lateral geniculate nucleus (LGN) of awake animals communicate significant or
unexpected visual events to cortex. The present study investigated this
hypothesis by examining the incidence of LT bursts in 146 cells recorded from the
LGN of three macaque monkeys. Bursts were defined as clusters of two or more
action potentials separated by not more than 4 ms and preceded by a > or = 100-ms
quiescent interval. The incidence of bursts was examined in several
intensive-training Go-NoGo and target selection tasks as well as in training-free
tasks where natural scenes with both familiar and novel contents were shown. Our
chief findings were as follows. 1) Bursts occur in the majority of cells under
every condition tested, 2) burst incidence is very low (<1 burst every 10 s), 3)
bursts occur in association with a receptive field stimulus on average only once
every 23 times in 65% of cells tested, 4) cells responding with bursts to the
stimulus also tended to exhibit higher levels of spontaneous bursting, 5) the
presence of bursts did not depend on the novelty of the stimulus or its
behavioral relevance. When the monkeys explored static natural scenes, 6) bursts
were not correlated with short-term changes in the image sampled by the cell's
receptive field during saccades. Burst incidence 7) did not increase when images
were novel or when they evoked an emotional reaction, and 8) bursts did not
decrease when images were familiar. 9) Bursts were not correlated with saccades
in the dark, but 10) more spikes participated in bursts in the dark. Although
these results confirm the occurrence of LT bursts in LGN cells of awake monkeys,
they do not support the hypothesis that these bursts are a privileged means of
transferring sensory information, that they signal unexpected or significant
visual events, or that they are involved uniquely in the coding of natural
scenes.
Típus:
Article
PeerReviewed
Formátum:
text
Azonosító:
Ruiz, O. and Royal, D. and Sáry, Gyula (2006) Low-threshold Ca2+-associated bursts are rare events in the LGN of the awake behaving monkey. JOURNAL OF NEUROPHYSIOLOGY, 95 (6). pp. 3401-3413. ISSN 0022-3077
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