Aguila Jordi, Cudeiro F Javier, Rivadulla Casto
Neurocom, School of Health Sciences and Centro de Investigacións Científicas Avanzadas (CICA), Institute of Biomedical Research (INIBIC), University of A Coruña, 15006 A Coruña, Spain.
Cerebral Stimulation Center of Galicia, 15009 A Coruña, Spain.
Cereb Cortex. 2017 Jun 1;27(6):3331-3345. doi: 10.1093/cercor/bhx071.
In awake monkeys, we used repetitive transcranial magnetic stimulation (rTMS) to focally inactivate visual cortex while measuring the responsiveness of parvocellular lateral geniculate nucleus (LGN) neurons. Effects were noted in 64/75 neurons, and could be divided into 2 main groups: (1) for 39 neurons, visual responsiveness decreased and visual latency increased without apparent shift in receptive field (RF) position and (2) a second group (n = 25, 33% of the recorded cells) whose excitability was not compromised, but whose RF position shifted an average of 4.5°. This change is related to the retinotopic correspondence observed between the recorded thalamic area and the affected cortical zone. The effect of inactivation for this group of neurons was compatible with silencing the original retinal drive and unmasking a second latent retinal drive onto the studied neuron. These results indicate novel and remarkable dynamics in thalamocortical circuitry that force us to reassess constraints on retinogeniculate transmission.
在清醒的猴子中，我们使用重复经颅磁刺激（rTMS）来局部灭活视觉皮层，同时测量小细胞外侧膝状体核（LGN）神经元的反应性。在75个神经元中有64个观察到了效应，这些效应可分为两大类：（1）对于39个神经元，视觉反应性降低，视觉潜伏期增加，而感受野（RF）位置无明显偏移；（2）第二组（n = 25，占记录细胞的33%），其兴奋性未受影响，但其RF位置平均偏移了4.5°。这种变化与在记录的丘脑区域和受影响的皮层区域之间观察到的视网膜拓扑对应关系有关。对于这组神经元，灭活的效应与沉默原始视网膜驱动并揭示作用于所研究神经元的第二个潜在视网膜驱动相一致。这些结果表明丘脑皮质回路中存在新的显著动态变化，这迫使我们重新评估视网膜膝状体传递的限制因素。
