Cortical Interactions Of Parallel Afferent Channels Underlying Visual Perception, Attention And Memory
Funder
National Health and Medical Research Council
Funding Amount
$410,250.00
Summary
The visual pathways from the eyes to the brain consist of distinct groups of cells which are specialised to signal different aspects of the visual scene such as colour, contrast and movement. As the information they carry is relayed through and processed in many different regions of the brain these parallel information channels were, until recently, believed to remain completely separate from each other. Furthermore, it had been proposed that as the information reaches the visual neocortex the i ....The visual pathways from the eyes to the brain consist of distinct groups of cells which are specialised to signal different aspects of the visual scene such as colour, contrast and movement. As the information they carry is relayed through and processed in many different regions of the brain these parallel information channels were, until recently, believed to remain completely separate from each other. Furthermore, it had been proposed that as the information reaches the visual neocortex the information is channeled through two main largely parallel information processing streams, a dorsal stream to the parietal cortex (a where system) and a ventral stream to the temporal cortex (a what system). However, our recent functional studies (and anatomical studies from other laboratories) have indicated that the different information channels do interact already at a relatively early level of the visual pathway, namely in the primary visual cortex. We have shown this in two ways: (1) there is convergence of different information channels on individual neurones in the primary visual cortex; (2) signals from the faster where pathway comes back to the primary visual cortex to gate the slower channels going into the ventral what pathway. We have seen this occur in an attention paradigm and in a memory task. We will explore these interactions further to test hypotheses about: (1) how the convergence of different information channels relate to the functional and anatomical architecture of the visual cortex; (2) investigate at length the most poorly understood, the so-called koniocellular pathway from the retina to the cortex. This pathway seems to contain a specialised component which carries information about blue objects; (3) identify the source of the spotlight of attention we have discovered and (4) how and from where early visual structures receive the gating inputs in certain memory tasks.Read moreRead less
Effects Of Saccadic Eye Movements On Perception And Visual Memory.
Funder
National Health and Medical Research Council
Funding Amount
$255,750.00
Summary
We all make rapid eye movements, called saccades, three times a second all our waking lives. They allow us to direct our gaze at what catches our attention, but they sweep images across our retinas and alter all the linkages between the eyes and the brain. The question at the heart of this project is how the visual system maintains perceptual stability given the disruption to the flow of visual input that saccades necessarily cause. It has to do more than suppress disturbing signals; it has to l ....We all make rapid eye movements, called saccades, three times a second all our waking lives. They allow us to direct our gaze at what catches our attention, but they sweep images across our retinas and alter all the linkages between the eyes and the brain. The question at the heart of this project is how the visual system maintains perceptual stability given the disruption to the flow of visual input that saccades necessarily cause. It has to do more than suppress disturbing signals; it has to link the present with the past. In recent years we and others have made substantial progress toward answering this question. In this project we plan a four-pronged attack that will take us further. We anticipate that our results will reveal how the visual system maintains and adjusts its representations of space and time, integrates signals from before and after saccades, and regulates the flow of information from memory to achieve a seamless melding of the present with the past. This project is not directed at any particular clinical problem, but disturbances of perception and memory are aspects of many clinical conditions. If we succeed in our aims what we discover will constitute a major scientific discovery which should find application to many conditions in which perception and memory are disturbed, from dyslexia to brain damage and even affective disorders such as schizophrenia and depression.Read moreRead less
Functional Interactions Between Primate Cortical Areas In Tasks Involving Attention And Short-term Memory
Funder
National Health and Medical Research Council
Funding Amount
$267,280.00
Summary
To navigate and operate in the cluttered and dynamic sensory world around us, our brains need to be able to attend to specific objects or features in the environment, identify them and also know where they exist at any one instant of time, prior to performing the appropriate action. The attention, memory, decision and motor components involved in this process possibly involve a variety of cortical areas and neuronal operations. The special primate preparation we have developed permits us to eluc ....To navigate and operate in the cluttered and dynamic sensory world around us, our brains need to be able to attend to specific objects or features in the environment, identify them and also know where they exist at any one instant of time, prior to performing the appropriate action. The attention, memory, decision and motor components involved in this process possibly involve a variety of cortical areas and neuronal operations. The special primate preparation we have developed permits us to elucidate at a neuronal level many of these brain mechanisms. By recording neuronal activities in two different cortical areas simultaneously as the monkey performs a memory task that he has been trained on, we will test the following ideas: (1) A cortical region in the dorsal, parietal stream directs spatial attention by gating other visual areas to process only a selected region of the visual world (2) A region in the ventral, temporal stream directs attention to specific features in the visual world by gating earlier cortical areas (3) The parietal cortical areas that mediate intention for action hold the relevant information in working memory till it is forwarded to the more anterior premotor areas. These experiments have the potential to reveal the basic neuronal scheme that underpins functions such as attention, visual recognition and memory, which are impaired in many neurological disorders.Read moreRead less
Interactions Between Afferent Channels In Vision: Basic Neurophysiology And Implications For The Pathology Of Dyslexia
Funder
National Health and Medical Research Council
Funding Amount
$423,662.00
Summary
We intend to study the interactions between different information channels in the primate visual system. The pathways from the eyes to the brain consist of different types of nerve fibres carrying distinct sorts of information. These channels have been believed to remain separate as they transmit the information through various levels of the brain. Finally, in the neocortex, it has been suggested that the visual information goes along two major streams, one dorsally to the parietal cortex and th ....We intend to study the interactions between different information channels in the primate visual system. The pathways from the eyes to the brain consist of different types of nerve fibres carrying distinct sorts of information. These channels have been believed to remain separate as they transmit the information through various levels of the brain. Finally, in the neocortex, it has been suggested that the visual information goes along two major streams, one dorsally to the parietal cortex and the other ventrally to the temporal cortex. Based upon recent studies, we question this strict segregation of the pathways and propose to study how interactions occur between the two streams and whether the two channels do come together at early levels of the visual pathway. We will also test our idea whether, of the dorsal and ventral streams, one stream might actually gate the other and decide what goes through the other stream. In fact, from our own recent studies, we have reason to believe that the way our attentional system might operate to select salient aspects of the visual scene may be through the dorsal stream selecting what goes into the ventral stream, which seems to be responsible for identifying objects. In the proposed project we will test this idea rigorously. From various lines of evidence, we also argue that the neural mechanisms that underlie this attentional spotlight is exploited by human children when they learn to read. It follows that any defect in the dorsal pathway or in the fibres and cells that feed into this will cause difficulties in reading. We believe this to be the underlying problem in dyslexic children. The project will undertake a number of experiments to test this idea.Read moreRead less
The Genetics Of Cognitive Deficits In Attention Deficit Hyperactivity Disorder (ADHD)
Funder
National Health and Medical Research Council
Funding Amount
$675,512.00
Summary
Attention deficit hyperactivity disorder (ADHD) is a common psychiatric disorder of childhood that is marked by age-inappropriate levels of inattention and-or hyperactivity-impulsivity. The disorder appears genetic with a number of different genes likely contributing risk for ADHD. This project takes an innovative approach by asking whether there are different genetic profiles associated with children with ADHD who do or do not have neurocognitive deficits.
Direct And Indirect Assessment Of 5 Ability Structures Underlying 7 Categories Of Childhood Psychopathology
Funder
National Health and Medical Research Council
Funding Amount
$263,311.00
Summary
This research has four main aims. First, we aim to obtain detailed knowledge of how normal children develop a range of different abilities, including motor coordination, language skills, the ability to understand other people, self-control, and general cognitive ability. Second, with this knowledge of normal development we will be able to identify cases in which normal development does not occur and to identify the exact ability area(s) in which development is abnormal. Patterns of abnormal deve ....This research has four main aims. First, we aim to obtain detailed knowledge of how normal children develop a range of different abilities, including motor coordination, language skills, the ability to understand other people, self-control, and general cognitive ability. Second, with this knowledge of normal development we will be able to identify cases in which normal development does not occur and to identify the exact ability area(s) in which development is abnormal. Patterns of abnormal development will be studied in children with one of seven disorders, including Autistic Disorder, Intellectual Disability, and Developmental Coordination Disorder. Third, we will assess whether deficits in some ability correspond to impairments in just one basic psychological structure (e.g., language deficits are related to impairment in the ability to recognise sounds) or whether they can be due to impairments in several structures (e.g., the ability to recognise faces or the ability to maintain attention). Finally, we will investigate whether and how impairments in one or more basic psychological structures can result in deficits in one or more of the ability areas that are the basis for the diagnosis of one or more developmental disorders. This research is expected to lead to an enhanced ability to assess the exact nature of any given developmental disorder which, in turn, should enhance clinical care of the child.Read moreRead less