Interactions between cat striate cortex neurons

Abstract

A series of simultaneous recordings from several striate cortex neurons were made in paralyzed, anesthetized cats. Recordings were obtained with one or two bundles of extra fine wires and originated from one and two cortical orientation columns. Standard PST histograms and, in some cases, response planes were used to analyse the neuronal receptive fields. Functional connectivity between neurons was assessed by cross-correlation of their spike trains. It was found that 61% of neuronal pairs found within a column shared the same input, either excitatory or inhibitory, Even if neurons in a pair belonged to two different columns separated by 1mm lateral distance, 40% of pairs still exhibited shared input coordination. This type of coordination could also encompass all combinations of simple and complex fields in the pair. Direct connections between neurons were found almost exclusively within columns: excitatory connections were found in 20% of cases and inhibitory in 8%. Direct connections were often accompanied by the other types of interactions. Only one example of excitatory and one of inhibitory direct connections were found between columns. In both cases preferred orientations were almost identical.

Lack of Patchy Horizontal Connectivity in Primary Visual Cortex of a Mammal without Orientation Maps

“…If we examine orientation preference differences only for cell pairs with covariation strengths in class 4, as in Figure 6C, it is apparent that even among strong covariations there is no relationship between orientation preference and covariation strength. The lack of a relationship between correlations and orientation preference is markedly different from findings in cat (Michalski et al, 1983;Ts'o et al, 1986).…”

“…6 B). Cells closer than 300 m were much more likely to show class 3 or class 4 covariation strength than cells separated by 300 -600 m and cells separated by more than 600 m. This distance dependency is very similar to results reported in cat V1 by Das and Gilbert (1999), who examined correlations in pairs of neurons at relatively short distances (most separations Ͻ600 m) but is different from Michalski et al (1983), who specifically targeted cells in adjacent orientation columns separated by up to 1 mm and reported that 40% of such cell pairs showed significant interactions. The lack of high correlations at longer distances in squirrel is in good agreement with the anatomical data that shows a rapid drop-off in the number of connections with distance and a lack of patchy regions at long distances that might have shown strong functional interactions.…”

“…The lack of high correlations at longer distances in squirrel is in good agreement with the anatomical data that shows a rapid drop-off in the number of connections with distance and a lack of patchy regions at long distances that might have shown strong functional interactions. The high degree of covariation observed across iso-orientation domains separated by long distances (Ͼ1 mm) in studies of carnivore V1 (Michalski et al, 1983;Ts'o et al, 1986;Chiu and Weliky, 2001) likely reflects the high degree of polysynaptic interaction within and among local isoorientation domains, whereas an animal lacking patchy connectivity would not be expected to show strong covariation at long distances very frequently. For example, if one imagines that polysynaptic interactions two or three synapses away might be observable in these correlations, there are likely to be many paths between two cells separated by 1 mm in neighboring isoorientation domains in cat, whereas in squirrel there are probably few such paths between cells separated by 1 mm.…”

Learning and Adaptation in a Recurrent Model of V1 Orientation Selectivity

“…To achieve strong orientation tuning typically observed in V1, recurrent excitatory and inhibitory connections are introduced among the model V1 cells. Following the experimental evidence (Ferster 1986;Michalski et al 1983), both excitatory and inhibitory connections in the model are strongest among cells with the same preferred orientation, and they drop off with increasing difference between the preferred orientations of the cells (Fig. 1B).…”

Cross-correlation analysis of neuronal activities.

“…On the other hand, the parameter given by the ratio of the number of correlated spikes relative to the number of the postsynaptic spikes has been proposed as the "contribution" by LEVICK et al [52]. Although this parameter cannot express the synaptic connectivity [1], this measured parameter has been used by many investigators to express the connectivity [63,[82][83][84]. KWAN et al [51] have proposed the combination of these two ratios to express synaptic strength.…”