Columnar organization of the mammalian visual cortex and its vulnerability following lesion in adult cats

Abstract

It is well known that in the mammalian visual cortex the neurons, sharing similar response properties, are grouped together into functional units, known as cortical columns. The orientation and ocular dominance columnar organization is a fundamental element for both the anatomical and physiological features of the visual cortex. Nonetheless, little is known about the functional restoration of matured columnar columns following injury. In the present study, the visual cortex of adult cats was studied electrophysiologically, whereas the primary goal of the study was to reveal the functional stability of the columns, disconnected from the main visual input. Experiments were performed on the primary visual cortex (area 17) of 13 anaesthetized and paralyzed adult cats. The columnar distortion was produced by surgical incision perpendicular to the cortical columns. The single unit activity was recorded from 1186 visual cells (experimental groups) in areas proximal and distal to the lesion and, compared to data, received from intact visual cortex (control group). The results indicate that most of the visually responsive cells were found to be selective to specific orientation in all experimental groups (75-100%) similar to the normal control group (78%). Moreover, the distribution of orientation-specific cells was very similar in all experimental and control groups (p > 0.05), as well as in both recording areas (p > 0.05). The percentage of binocular cells was significantly lower in all experimental groups (23-49%) in comparison to the control (80%). However, the distribution of the binocular cells revealed the significant similarity between the experimental and control groups (p > 0.05). An additional finding of the study is that the visual responsiveness of cells was significantly reduced in all experimental groups: only 28-49% of cells were found to be responsive following injury, as compared to 86% in normal control group (p < 0.001). The distribution of cells has also been analysed in accordance with their directional specificity and it has been found that the majority of cells in the experimental groups were found to be bias and non-specific to light stimuli (52-84%) as compared normal controls (21%) (p < 0.001). It has been concluded that, despite the fact that no improvement in visual function was found, the inherent structure of the disrupted cortical columns in the visual cortex was generally preserved. Therefore, the disruption of the columnar connection does not lead to remarkable distortion of the connectivity pattern on the whole, though it does reduce the responsiveness level there. It was concluded that the columnar structure for both orientation and ocular dominance is characterized by high stability, which enables visual processing with minimal brain connections.

A comparative quantitative analysis of cytoarchitecture and minicolumnar organization in Broca's area in humans and great apes

“…In contrast, a considerable number of studies have reported minicolumn spacing for a variety of smaller mammals: rhesus macaque temporal cortex (Buxhoeveden and Casanova, 2000;Buxhoeveden et al, 2001a,b); rhesus macaque motor cortex (Amirikian and Georgopoulos, 2003); cat primary somatosensory cortex (Favorov and Diamond, 1990;Tommerdahl et al, 1993); cat visual cortex (Gurshumov and Yinon, 2005); rat somatosensory cortex (Tommerdahl et al, 1993;Joublin et al, 1996;Lubke and Feldmeyer, 2007), and for humans: cingulate and pericingulate cortex (Schlaug et al, 1995); primary auditory cortex (Chance et al, 2006); posterior auditory association region (Buxhoeveden and Casanova, 2000;Buxhoeveden et al, 2001b;Chance et al, 2006). These studies demonstrate that humans have larger minicolumns than other smaller mammals.…”

Micro-field evoked potentials recorded from the porcine sub-dural cortical surface utilizing a microelectrode array

“…The details of this columnar neuronal circuitry have been particularly well described for the primary visual cortex. Within the visual cortex, each cortical column receives information from each eye in an alternating (left eye, right eye) pattern (Mountcastle, 1997;Gurshumov and Yinon, 2005). Additionally, detailed studies are widely available for the somatosensory cortex, auditory cortex, and motor cortex (Mountcastle, 2003).…”

Decitabine improves patient outcomes in myelodysplastic syndromes

“…In contrast, a considerable number of studies have reported minicolumn spacing for a variety of smaller mammals: rhesus macaque temporal cortex (Buxhoeveden and Casanova,2000; Buxhoeveden et al,2001a,b); rhesus macaque motor cortex (Amirikian and Georgopoulos,2003); cat primary somatosensory cortex (Favorov and Diamond,1990; Tommerdahl et al,1993); cat visual cortex (Gurshumov and Yinon,2005); rat somatosensory cortex (Tommerdahl et al,1993; Joublin et al,1996; Lubke and Feldmeyer,2007), and for humans: cingulate and pericingulate cortex (Schlaug et al,1995); primary auditory cortex (Chance et al,2006); posterior auditory association region (Buxhoeveden and Casanova,2000; Buxhoeveden et al,2001b; Chance et al,2006). These studies demonstrate that humans have larger minicolumns than other smaller mammals.…”