Suppression of V1 Feedback Produces a Shift in the Topographic Representation of Receptive Fields of LGN Cells by Unmasking Latent Retinal Drives.
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.
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.
Jordi
J
Aguila
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.
F Javier
FJ
Cudeiro
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.
Casto
C
Rivadulla
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D056228:Feedback, Sensory / Q000502:physiology*; D005829:Geniculate Bodies / Q000166:cytology*; D008253:Macaca mulatta; D008297:Male; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation; D012160:Retina / Q000502:physiology; D065908:Transcranial Direct Current Stimulation; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*; D014851:Wakefulness
LGN; RFs; corticothalamic feedback; neuroplasticity; v1; visual system