Neural Mechanisms Underlying Human Grasp And Manipulation
Funder
National Health and Medical Research Council
Funding Amount
$396,100.00
Summary
We rely on hand function in a multitude of simple tasks that we tend to take for granted but that are essential in our everyday lives; some examples are turning on a tap, doing up shoelaces, or holding a cup. Many people in the community are disabled by impaired hand function resulting from lesions of the central nervous system or peripheral nerve lesions. The size of the problem is enormous; manual dexterity is affected in approximately 20,000 new stroke patients each year in Australia as well ....We rely on hand function in a multitude of simple tasks that we tend to take for granted but that are essential in our everyday lives; some examples are turning on a tap, doing up shoelaces, or holding a cup. Many people in the community are disabled by impaired hand function resulting from lesions of the central nervous system or peripheral nerve lesions. The size of the problem is enormous; manual dexterity is affected in approximately 20,000 new stroke patients each year in Australia as well as in other neurological diseases such as neuropathies, nerve injuries, cerebral palsy and many others. The broad aim of this study is to investigate the poorly understood neural mechanisms that underlie sensorimotor control of hand function. We will target a specific aspect of manual dexterity that is crucial for the execution of common everyday tasks, like pouring liquid from a bottle, in which the digits are subjected to torsional loads. In order to maintain stable grasps, the motor control system must rapidly and automatically adjust the grip forces employed to meet the demands imposed by the changing torsion. This is only possible because of sensory feedback from the hand, a large component of which arises from the cutaneous mechanoreceptive afferent fibres. In the first two years we will use a combined approach of neural recording from peripheral nerves in anaesthetised monkeys and psychophysics experiments in normal humans to answer the general question: how does the population of cutaneous afferents provide precise feedback about torsion on the digits? In the third year we will perform key experiments in humans, using microneurography to record from their peripheral nerves. This will establish any differences between human and monkey mechanoreceptors.Read moreRead less
Integrative Role Of Feedback Projections To Cat Primary Visual Cortex
Funder
National Health and Medical Research Council
Funding Amount
$293,321.00
Summary
Although in the last decade termed The Decade of the Brain we have learned a lot about the brain, the gaps in our understanding of brain functions are still enormous. The analysis of information in the sensory parts of the brain appears to be arranged in a distributed - hierarchical way. For example, different types of nerve fibres leaving the eye carry fairly generalised information about the external visual world along distinct parallel information channels. By the time the signals reach cereb ....Although in the last decade termed The Decade of the Brain we have learned a lot about the brain, the gaps in our understanding of brain functions are still enormous. The analysis of information in the sensory parts of the brain appears to be arranged in a distributed - hierarchical way. For example, different types of nerve fibres leaving the eye carry fairly generalised information about the external visual world along distinct parallel information channels. By the time the signals reach cerebral cortex there is a dramatic increase in complexity of visual stimuli to which cells respond (orientation, length and direction of movement of contours became important). There are at least two parallel feedforward information processing streams across the cerebral cortex involving a number of relay stations at each of which there are further specializations. For example, cells in one area appear to respond only to faces while in some other areas cells respond to motion in particular directions almost irrespective of the position of the stimuli. In the human there are more than 30 visual cortical areas. What is very surprising that from all these areas there are extensive feedback pathways running back to the lower-order areas. The feedback pathways appear to largely criss-cross different information processing streams and their function is very poorly understood. We will record from cells in lower-order areas noting the way they respond to different stimuli. Then we will block the feedback pathway from a particular higher-order area by cooling the area to about 10oC. We have confirmed that this prevents nerve impulses leaving the cooled area. Then we repeat our tests on the cell in the lower-order area. Comparing the responses with and without feedback activity will tell us what the feedback is doing. Understanding the function of feedback pathways hopefully would help us to understand the mechanisms underlying some subtle psychoneurological diseases.Read moreRead less
Neural Mechanisms In Tactile, Kinaesthetic And Pain Sensation
Funder
National Health and Medical Research Council
Funding Amount
$644,113.00
Summary
Our knowledge of the world around us depends upon our sensory systems which provide a series of windows on the world, enabling the mind and brain to sample information about selected events through the energy forms that impinge upon us. Much of this sensing process takes place through our special sense systems such as the eye, the ear, and the taste and olfactory systems. However, other crucial sensory systems are more generalized throughout the body and are referred to as the somatic sensory sy ....Our knowledge of the world around us depends upon our sensory systems which provide a series of windows on the world, enabling the mind and brain to sample information about selected events through the energy forms that impinge upon us. Much of this sensing process takes place through our special sense systems such as the eye, the ear, and the taste and olfactory systems. However, other crucial sensory systems are more generalized throughout the body and are referred to as the somatic sensory systems. These include our senses of touch, temperature, pain and body position, the last of which is known as our kinaesthetic sense. Our research into the neural mechanisms in sensation and perception is concerned with the tactile, kinaesthetic and pain senses. Although many thousands of nerve fibres travel in the nerves arising from particular regions of the skin or from individual muscles or joints, the sensory nerve fibres that serve these forms of sensation fall into fewer than ten broad classes, made up of five major tactile classes, two or three major kinaesthetic classes, and two broad groups of fibres that mediate pain sensation. However, there is quite striking evidence that when single fibres of these different classes are activated in conscious human subjects, there are marked differences among the fibre classes in their capacity to generate a perceptual response. Under the new NH and MRC grant we propose to examine the transmission and processing of input signals from these fibre classes at the highest levels of the brain, in particular, within the cerebral cortex, in order to reveal the neural mechanisms responsible for their differential perceptual contributions. The proposed analysis will provide fundamental insights into the neural basis for perceptual recognition and will provide information that may be important for our eventual understanding of the disorders of sensory perception that characterize psychiatric conditions such as schizophreniaRead moreRead less