Abstract Abstract: We studied the multiunit responses to moving and static stimuli from 585 cell clusters in area MT using multi-electrode arrays. Our aim was to explore if MT columns exhibit any larger-scale tangential organization or clustering based on their response properties. Neurons showing both motion and orientation selectivity were classified into four categories: 1- Type I (orientation selectivity orthogonal to the axis of motion); 2- Type II (orientation selectivity coaxial to the axis of motion); 3- Type DS (significant response to moving stimuli, but non-significant response to static stimuli); and 4- Type OS (significant orientation selectivity, but non-significant direction selectivity). Type I (34%), Type II (24%) and Type DS (32%) clusters were the most predominant and may be associated with different stages of motion processing in MT. On the other hand, the rarer Type OS (9%) may be integrating motion and form processing. Type I and unidirectional sites were the only classes to exhibit significant clustering. Type OS sites showed a trend for clustering, which did not reach statistical significance. We also found a trend for unidirectional sites to have bidirectional sites as neighbors. In conclusion, neuronal clustering associated with these four categories may be related to distinct MT functional circuits.
We investigated the effect of a scene on the activity of cells in the anterior inferotemporal (AIT) cortex while the monkey performed a saccadic eye movement (SEM) task with and without the context of a scene (gray frame). Most neurons did not code for the presence of a scene when it appeared alone (monkey free viewing) or when the monkey was fixating. Nevertheless, when a peripheral target was turned on and the monkey had to make a SEM to it, some cells were capable of differentially coding the presence of the scene before and after the saccade.
Nós investigamos o efeito de uma cena na atividade de células do córtex inferotemporal anterior enquanto o macaco executava uma tarefa de movimento sacádico dos olhos, com e sem o contexto de uma cena (moldura retangular cinza). A maioria dos neurônios não codificou a presença da cena quando ela foi apresentada sozinha no campo visual e o animal estava livre para mover os olhos (macaco na condição de visão livre) ou quando o animal estava fixando um alvo na tela. No entanto, quando um alvo periférico era apresentado e o animal tinha que fazer um movimento sacádico para o alvo, algumas células foram capazes de codificar diferencialmente a presença da cena antes ou depois de um movimento sacádico.