Ortuño Tania, Grieve Kenneth L, Cao Ricardo, Cudeiro Javier, Rivadulla Casto
Neuroscience and Motor Control Group, NEUROcom, Department of Medicine, University of A Coruña Coruña, Spain ; Biomedical Research Institute of A Coruna (INIBIC) Coruña, Spain.
Faculty of Life Science, University of Manchester Manchester, UK.
Front Behav Neurosci. 2014 May 30;8:198. doi: 10.3389/fnbeh.2014.00198. eCollection 2014.
The lateral geniculate nucleus is the gateway for visual information en route to the visual cortex. Neural activity is characterized by the existence of two firing modes: burst and tonic. Originally associated with sleep, bursts have now been postulated to be a part of the normal visual response, structured to increase the probability of cortical activation, able to act as a "wake-up" call to the cortex. We investigated a potential role for burst in the detection of novel stimuli by recording neuronal activity in the lateral geniculate nucleus (LGN) of behaving monkeys during a visual detection task. Our results show that bursts are often the neuron's first response, and are more numerous in the response to attended target stimuli than to unattended distractor stimuli. Bursts are indicators of the task novelty, as repetition decreased bursting. Because the primary visual cortex is the major modulatory input to the LGN, we compared the results obtained in control conditions with those observed when cortical activity was reduced by TMS. This cortical deactivation reduced visual response related bursting by 90%. These results highlight a novel role for the thalamus, able to code higher order image attributes as important as novelty early in the thalamo-cortical conversation.
外侧膝状体核是视觉信息通向视觉皮层的门户。神经活动的特征是存在两种放电模式：爆发式和紧张式。爆发式最初与睡眠有关，现在被认为是正常视觉反应的一部分，其结构是为了增加皮层激活的概率，能够作为对皮层的“唤醒”信号。我们通过在视觉检测任务期间记录行为猴子外侧膝状体核（LGN）中的神经元活动，研究了爆发式在新刺激检测中的潜在作用。我们的结果表明，爆发式通常是神经元的首次反应，并且在对被关注的目标刺激的反应中比在对未被关注的干扰刺激的反应中更为频繁。爆发式是任务新颖性的指标，因为重复会减少爆发式。由于初级视觉皮层是LGN的主要调节性输入，我们将对照条件下获得的结果与经重复经颅磁刺激（TMS）降低皮层活动时观察到的结果进行了比较。这种皮层失活使与视觉反应相关的爆发式减少了90%。这些结果突出了丘脑的一个新作用，即在丘脑-皮层对话早期能够编码与新颖性同样重要的高阶图像属性。
