Posts tagged spatial awareness
Articles and news from the latest research reports.
New study finds blind people have the potential to use their ‘inner bat’ to locate objects
New research from the University of Southampton has shown that blind and visually impaired people have the potential to use echolocation, similar to that used by bats and dolphins, to determine the location of an object.
The study, which is published in the journal Hearing Research, examined how hearing, and particularly the hearing of echoes, could help blind people with spatial awareness and navigation. The study also examined the possible effects of hearing impairment and how to optimise echolocation ability in order to help improve the independence and quality of life of people with visual impairments.
Researchers from the University of Southampton’s Institute of Sound and Vibration Research (ISVR) and University of Cyprus conducted a series of experiments with sighted and blind human listeners, using a ‘virtual auditory space’ technique, to investigate the effects of the distance and orientation of a reflective object on ability to identify the right-versus-left position of the object. They used sounds with different bandwidths and durations (from 10–400 milliseconds) as well as various audio manipulations to investigate which aspects of the sounds were important. The virtual auditory space, which was created in ISVR’s anechoic chamber, allowed researchers to remove positional clues unrelated to echoes, such as footsteps and the placement of an object, and to manipulate the sounds in ways that wouldn’t be possible otherwise (e.g. get rid of the emission and present the echo only).
Dr Daniel Rowan, Lecturer in Audiology in ISVR and lead author of the study, says: “We wanted to determine unambiguously whether blind people, and perhaps even sighted people, can use echoes from an object to determine roughly where the object is located. We also wanted to figure out what factors facilitate and restrict people’s abilities to use echoes for this purpose in order to know how to enhance ability in the real world.”
The results showed that both sighted and blind people with good hearing, even if completely inexperienced with echolocation, showed the potential to use echoes to tell where objects are. The researchers also found that hearing high-frequency sounds (above 2 kHz) is required for good performance, and so common forms of hearing impairment will probably cause major problems.
Dr Daniel Rowan adds: “Some people are better at this than others, and being blind doesn’t automatically confer good echolocation ability, though we don’t yet know why. Nevertheless, ability probably gets even better with extensive experience and feedback.
“We also found that our ability to use echoes to locate an object gets rapidly worse with increasing distance from the object, especially when the object is not directly facing us. While our experiments purposely removed any influence of head movement, doing so might help extend ability to farther distances. Furthermore, some echo-producing sounds are better for determining where an object is than others, and the best sounds for locating an object probably aren’t the same as for detecting the object or determining what, and how far away, the object is.”
The knowledge gained from this study will help researchers to develop training programmes and assistive devices for blind people and sighted people in low-vision situations. The team is also extending their research to investigate finding of objects in three-dimensional space and why some blind people seem to be able to outperform others, including sighted people.
Scientists devise unique stroke assessment tool
Scientists at the University of Birmingham have devised a unique screening instrument that provides a ‘one-stop’ brain function profile of patients who have suffered stroke or other neurological damage.
The Birmingham Cognitive Screen (BCoS) can offer a visual snapshot of the cognitive abilities and deficits of an individual which can then be used to guide clinical decision making.
Following brain damage, including stroke, head injury, carbon monoxide poisoning and degenerative change, people can experience a range of cognitive problems as well as difficulty with physical movement. Cognitive problems strongly influence a patient’s ability to recover but patients are not routinely screened to detect them.
The first test of its kind, BCoS has been designed by a team of brain experts co-ordinated by Research Fellow Dr Wai-Ling Bickerton (also a chartered psychologist and occupational therapist) at the University of Birmingham in collaboration with Professors Glyn Humphreys and Jane Riddoch at Oxford University and Dana Samson at Louvain University.
Comprising a user-friendly manual, a test book, a CD containing Auditory Attention Test stimuli, a supply of examiner and examinee booklets and a zip-up pouch of test objects, the test takes 45-60 minutes and is carried out by trained health professionals and covers a range of cognitive abilities, including attention, executive function, spatial awareness, speech and language processing, action planning and control, memory, and number processing.
‘Through research outcomes supported by the Stroke Association, BCoS has already been used to successfully assess more than 1,000 stroke survivors in the West Midlands,’ explains Dr Bickerton. ‘BcoS has been validated against “standard” neuropsychological tests and assessed against measures of cognition and activities of everyday living for patients in the chronic stage.
‘The test has been designed to be highly inclusive and, as such, is an optimal tool for most stroke survivors regardless of the cognitive effects of stroke,’ she says. ‘It is also applicable to individuals with brain injury or dementia.
(Source: birmingham.ac.uk)
Brain rhythms help sense of location
Scientists have shed light on how mechanisms in the brain work to give us a sense of location. Research at the University of Edinburgh tracked electrical signals in the part of the brain linked to spatial awareness.
Sense of where we are
The study could help us understand how, if we know a room, we can go into it with our eyes shut and find our way around. This is closely related to the way we map out how to get from one place to another.
Brain’s electrical activity
Scientists found that brain cells, which code location through increases in electrical activity, do not do so by talking directly to each other. Instead, they can only send each other signals through cells that are known to reduce electrical activity. This is unexpected as cells that reduce electrical signalling are often thought to simply supress brain activity.
Rhythms of brain activity
The research also looked at electrical rhythms or waves of brain activity. Previous studies have found that spatial awareness is linked to not only the number and strength of electrical signals but also where on the electrical wave they occur.
The research shows that the indirect communication between nerve cells that are involved in spatial awareness also helps to explain how these electrical waves are generated. This finding is surprising because its suggests that the same cellular mechanisms allow our brains to work out our location and generate rhythmic waves of activity.
Spatial awareness and the brain’s electrical rhythms are known to be affected in conditions such as schizophrenia and Alzheimer’s disease. The scientists work could therefore help research in these areas.
Research
The study, funded by the Biotechnology and Biological Research Council, is published in the journal Neuron.
It looked at connections between nerve cells in the brain needed for spatial awareness in mice and then used computer modelling to recreate patterns of neural activity found in the brain.
Rhythms in brain activity are very mysterious and the research helps shed some light on this area as well as helping us understand how our brains code spatial information. It is particularly interesting that cells thought to encode location do not signal to each other directly but do so through intermediary cells. This is somewhat like members of a team not talking to each other, but instead sending messages via members of an opposing side. -Matt Nolan (Centre for Integrative Physiology)
(Source: ed.ac.uk)
Out of Sight, Out of Mind? How the brain codes its surroundings beyond the field of view
Even when they are not directly in sight, we are aware of our surroundings: so it is that when our eyes are fixed on an interesting book, for example, we know that the door is to the right, the bookshelf is to the left and the window is behind us. However, research into the brain has so far concerned itself predominantly with how information from our field of vision is coded in the visual cortex. To date it has not been known how the brain codes our surroundings beyond the field of view from an egocentric perspective (that is, from the point of view of the observer).
In the latest issue of the renowned journal Current Biology, Andreas Schindler und Andreas Bartels, scientists at the Werner Reichardt Center for Integrative Neuroscience (CIN) of the University of Tübingen, present for the first time direct evidence of this kind of spatial information in the brain.
The participants in their study found themselves in the center of a virtual octagonal room, with a unique object in each corner. As the brain’s activity was monitored by means of functional magnetic resonance imaging, the participants stood in front of one corner and looked at its object. Now they were instructed to determine the position of a second randomly chosen object within the room relative to their current perspective (for example, the object behind them). After a few trials the participant turned around so that the next object was brought into the field of view and the task was set up again. The whole procedure was repeated until every object had been looked at once.
The scientists discovered that patterns of activity in the parietal cortex code the participant’s egocentric position, that is, the relative position to his or her surroundings. The spatial information discovered there proved to be independent of the particular object, its absolute position in the room or that of the observer – i.e. it encoded egocentric spatial information of the three-dimensional surroundings. This result turns out to be particularly interesting because damage to the brain in the parietal cortex can lead to serious disruption of egocentric spatial awareness. Hence it is difficult for patients suffering from optical ataxia to carry out coordinated grasping movements. Lesions in the parietal cortex can also lead to a symptom called spatial neglect where patients have difficulties in perceiving their surroundings on the side opposite to the lesion. The brain areas identified in the present study coincided precisely with the areas of brain damage in such patients and provide for the first time insights regarding their function in the healthy brain.