In the areas of the brain where visual information is processed, cells respond to the presentation of visual stimuli by changing their pattern of electrical activity. At the first level of analysis, the primary visual cortex (V1), individual cells become active only if line segments or borders of a particular orientation are present in their field of detection, which encompasses a small part of the visual scene. Cells in other visual cortical areas (the extrastriate cortex) perform more complex ....In the areas of the brain where visual information is processed, cells respond to the presentation of visual stimuli by changing their pattern of electrical activity. At the first level of analysis, the primary visual cortex (V1), individual cells become active only if line segments or borders of a particular orientation are present in their field of detection, which encompasses a small part of the visual scene. Cells in other visual cortical areas (the extrastriate cortex) perform more complex detection tasks in comparison with those in V1, which demand integration of information coming from much larger portions of the visual scene. One example of these more complex properties is the phenomenon of long-range contour integration, where our visual system groups individual line segments having similar orientations, so that they are perceived as part of the same contour. This property is reflected in the electrical responses of cells in the dorsomedial visual area (DM). How are properties such as orientation specificity and long-range contour integration created? To begin addressing this question, we will investigate correlations between the physiological properties of identified cells, the spatial distribution of their information collecting regions (dendrites), and the anatomical pathways by which they receive information from other parts of the brain. This is a basic science study aimed at determining the extent to which the anatomical structure of the brain helps define the function of individual cells and brain areas. Its primary benefit will be to increase our understanding of the mechanisms underlying all sensory processing in the brain. The knowledge obtained may also lead to developments in areas of applied research including medicine and cognitive science (for example, understanding how the brain learns to interpret visual information in early life, and how visual processing degrades with ageing).Read moreRead less
Over thirty different areas, comprising nearly half the primate cerebral cortex, are involved in processing visual information. From the anatomical viewpoint, each of these areas should be capable of receiving visual information independently, through parallel anatomical channels involving the brainstem. Yet, it has been observed that lesion of one particular area (the primary visual area, V1) results in loss of vision. This raises several questions. What type of visual information is carried by ....Over thirty different areas, comprising nearly half the primate cerebral cortex, are involved in processing visual information. From the anatomical viewpoint, each of these areas should be capable of receiving visual information independently, through parallel anatomical channels involving the brainstem. Yet, it has been observed that lesion of one particular area (the primary visual area, V1) results in loss of vision. This raises several questions. What type of visual information is carried by the parallel pathways to the other visual areas? Why aren t these other areas capable of sustaining vision without V1? Do V1 lesions trigger changes in the adult brain, which affect the other visual areas? As a step towards answering these questions, we will study the neural pathways that convey visual information directly to the middle temporal area (MT). MT is one of the best-characterised visual areas, and the anatomy of its neural inputs is well known, facilitating the interpretation of the results. We will investigate the type of visual information being sent to MT after lesions of V1, as well as the changes in the electrical responses of MT cells which result from this type of condition. This is a basic science study, the primary benefit of which will be advancement of knowledge on the mechanisms that underlie visual processing in normal and pathological situations. However, this type of work may also lay the groundwork for developments in areas of applied research. These may include medicine (e.g. the design of better rehabilitation strategies for people with brain damage), robotics- artificial intelligence (e.g. the development of more robust artificial systems capable of vision), and cognitive sciences (e.g. a better understanding of factors that limit human responses to visual stimuli).Read moreRead less
Developmental Plasticity In The Nonhuman Primate Visual Cortex
Funder
National Health and Medical Research Council
Funding Amount
$464,417.00
Summary
A phenomenon that has puzzled many for a number of years is why damage to the visual brain during infancy has far less of an impact on visual capacity than the same lesion suffered later in life. This project hopes to uncover this mystery and see how brain 'wiring' is altered to compensate.