Selective interhemispheric circuits account for a cardinal bias in spontaneous activity within early visual areas.
Ongoing brain activity exhibits patterns resembling neural ensembles co-activated by stimulation or task performance. Such patterns have been attributed to the brain's functional architecture, e.g. selective long-range connections. Here, we directly investigate the contribution of selective connections between hemispheres to spontaneous and evoked maps in cat area 18 close to the 17/18 border. We recorded voltage-sensitive dye imaging maps and spiking activity while manipulating interhemispheric input by reversibly deactivating corresponding contralateral areas. During deactivation, spontaneous maps continued to be generated with similar frequency and quality as in the intact network but a baseline cardinal bias disappeared. Consistently, neurons preferring either horizontal (HN) or vertical (VN), as opposed to oblique contours, decreased their resting state activity. HN decreased their rates also when stimulated visually. We conclude that structured spontaneous maps are primarily generated by thalamo- and/or intracortical connectivity. However, selective long-range connections through the corpus callosum - in perpetuation of the long-range intracortical network - contribute to a cardinal bias, possibly, because they are stronger or more frequent between neurons preferring horizontal and/or cardinal contours. As those contours are easier perceived and appear more frequently in natural environment, long-range connections might provide visual cortex with a grid for probabilistic grouping operations in a larger visual scene.
Brain Institute, Federal University of Rio Grande do Norte (UFRN), 59056-450 Natal, Brazil.
Tiago Siebert
TS
Altavini
Brain Institute, Federal University of Rio Grande do Norte (UFRN), 59056-450 Natal, Brazil.
Sergio Andres
SA
Conde-Ocazionez
Albert-Ludwigs-University of Freiburg, 79104 Freiburg, Germany.
David
D
Eriksson
Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, 60528 Frankfurt, Germany.
Thomas
T
Wunderle
Brain Institute, Federal University of Rio Grande do Norte (UFRN), 59056-450 Natal, Brazil. Electronic address: kschmidt@neuro.ufrn.br.
Kerstin Erika
KE
Schmidt
D000818:Animals; D002415:Cats; D005074:Evoked Potentials, Visual; D005260:Female; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields; D014796:Visual Perception / Q000502:physiology*
Corpus callosum; Orientation preference; Resting state; Transition zone; VSD imaging