EyeProprio

EyeProprio

Lab news



Welcome to Alex Mitchell

SciencePosted by Daniela Balslev Wed, September 23, 2015 11:45:06
Alex has done her undergraduate studies at the University of York and has just finished a Master in Cognitive Neuroscience at UCL. She will be joining the lab in October to study towards a PhD. Her research project uses fMRI in healthy population and patients with spatial neglect to investigate how spatial representations for attention and movement emerge from sensory input and the efferent copy of the motor command.

Welcome!

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PhD position opening

SciencePosted by Daniela Balslev Mon, July 20, 2015 13:53:24
I am advertising a 3-year fully funded PhD position with start in september 2015 or as soon as possible after that. The student will use functional magnetic imaging (fMRI) in healthy participants and stroke patients to investigate how attention and the ocular sensorimotor signals are coupled and how errors in this coupling can lead to attention disorders such as spatial neglect.

Further details about the project, the supervisor, the environment and the application procedure are below:



The project:
The mind’s eye: the sensorimotor underpinnings of attention

A fundamental question in cognitive science is whether cognition and sensorimotor functions are entirely separate, as if the mind were a computer, or alternatively, whether the body influences the mind. The debate between advocates of the independent and the embodied views has been particularly heated in the discussion about the neural mechanisms of attention.

Attention is the ability to withdraw from some stimuli in order to deal effectively with others. Many of the brain areas that control attention also control eye movements. Is attention merely taking over some of the neural machinery evolved for gaze control, while operating completely independently? Or is attention nothing more than planned and withheld eye movements?

Recent breakthroughs in cognitive neuroscience allow now to design experiments that can answer these questions. I and others have mapped the pathways for the eye position signals in the central nervous system and provided tools to manipulate with these signals in the healthy human brain using transcranial magnetic stimulation (i.e. Balslev and Miall, J Neuroscience, 28:8968-72, 2008). There are two sources of eye position information: proprioception (the afferent input from the extraocular muscles) and corollary discharge (the copy of the oculomotor command). My work has shown that all interventions that change the oculoproprioceptive signal change the allocation of attention in space. This finding is crucial because it shows for the first time that a sensorimotor signal may have a specific function in attention (Balslev et al, J Neuroscience, 33:18311-8, 2013).

The aim of this research is to investigate how attention and the ocular sensorimotor input are coupled and how error in this coupling can cause spatial neglect.

The supervisor

I am an MD/PhD with 7 years postdoctoral experience, relocated to the UK one year ago to take up my first academic position. Personal fellowships from the Danish Medical Research Councils and the EU throughout the entire postdoctoral period have allowed me not only to develop an independent research agenda, but also to learn research methods in cognitive neuroscience from key experts. A list of my publications is here.

My lab has access to state-of-art equipment for transcranial magnetic stimulation (MagPro X100), eye tracking (EyeLink II) and functional magnetic resonance imaging (Siemens Trio, at the Clinical Research Centre, Ninewells Hospital Dundee). I would be happy to train the student to use these methods in healthy and patient populations. The oculomotor command and the re-afferent input for the eye muscles are fundamental building blocks in the neural representations that support movement, attention or object recognition. The goal is to understand how the brain represents space and how a breakdown in these representations in neurological patients can lead to disabilities such as optic ataxia, spatial neglect or simultanagnosia.

You can read more about my research here

The environment

The School of Psychology and Neuroscience at St Andrews has a strong Vision group using a variety of techniques (including psychophysics, eye movements, EEG, fMRI, TMS, neuropsychology and computational modelling) to study the human visual system. Ours is a highly multidisciplinary group, with members trained in biology, neuroscience, medicine, psychology, maths, physics and engineering. Potential students from these and related disciplines are welcome.

Funding

The PhD studentship covers tuition fees for UK/EU residents and provides a stipend of £13863/year. Candidates from overseas will have to find additional sources of support to cover the difference in the tuition fees
The project is funded via an award to Dr Daniela Balslev from the Wellcome Institutional Strategic Support Fund at the University of St Andrews.

Application procedure

Please send to daniela.balslev@st-andrews.ac.uk the following documents:
1. CV. This should include your personal details including your country of residence with a history of your education and employment to date.
2. Letter of motivation (half a page)
3. Two letters of reference
4. Copies of academic transcripts and degree certificates
5. Candidates who are not UK/EU residents will have to provide a statement about how they expect to cover the difference in the tuition fees (please see information about Funding above).

Applications will be accepted until the position is filled. Previous experience with Matlab, eye tracking, neuropsychology or functional magnetic resonance is not a prerequisite, but highly desirable.

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Welcome to Bobby Innes!

SciencePosted by Daniela Balslev Thu, September 25, 2014 13:07:08
Welcome to grad student Bobby Innes ! Bobby is joining the lab to investigate how the brain integrates the available sensorimotor signals to estimate the rotation of one's own eyes in the orbits. This information is critical for our ability to reach or attend to visual objects.

There are two eye position signals. Each signal has its advantages. The copy of the oculomotor command or corollary discharge is fast, available even before the eyes have moved. The reafferent feedback from the eye muscles or proprioception takes about 100 ms to reach the cerebral cortex. Oculoproprioception is, however, the most accurate reflection of the current eye position.

We are asking whether these signals are combined or not in a multimodal estimate of eye position. If they are combined, what is the criterion for their optimization ? Is this criterion fixed or flexible, tailored to suit the behavioral goal best ? Is the eye special or does the integration of the oculomotor and oculoproprioceptive signals follow the same principles as the sensorimotor integration for hand control or for multisensory integration ?

Hopefully we should soon have some answers, so stay tuned.

Bobby is funded by a BBSRC/EASBIO PhD studentship (2014-2018) and is supervised by Daniela Balslev and Tom Otto.



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New paper

SciencePosted by Daniela Balslev Wed, April 23, 2014 18:24:21

We think we figured out the disease mechanism in simultanagnosia (a neuropsychological disease in which the patients see only one object at the time, and are unable to identify large visual scenes). This is a rare but a very invalidating disease: the patients can no longer read or orient themselves in unfamiliar surroundings. I hope my research will help towards better assessment and treatment for these patients. However, I must confess that I did it also for a selfish reason. I find neuropsychological puzzles cool and I think I solved this one.

In brief, simultanagnosia patients cannot see what they are directly looking at. Central and peripheral objects compete for attention and objects in the periphery win this competition. If multiple objects are instead presented in the visual periphery only, the patients are better able to perceive them simultaneously.
An abstract is below:

Abnormal center-periphery gradient in spatial attention in simultanagnosia

Daniela Balslev, Bartholomaeus Odoj, Johannes Rennig, Hans-Otto Karnath

Journal of Cognitive Neuroscience (in press)



Patients suffering from simultanagnosia cannot perceive more than one object at a time. The underlying mechanism is incompletely understood. One hypothesis is that simultanagnosia reflects “tunnel vision”, a constricted attention window around gaze, which precludes the grouping of individual objects. Although this idea has a long history in neuropsychology, the question whether the patients indeed have an abnormal attention gradient around the gaze has so far not been addressed. Here we tested this hypothesis in two simultanagnosia patients with bilateral parieto-occipital lesions and two control groups, with or without brain damage. We assessed the subjects’ ability to discriminate letters presented briefly at fixation with and without a peripheral distractor or in the visual periphery, with or without a foveal distractor. A constricted span of attention around gaze would predict an increased susceptibility to foveated versus peripheral distractors. Contrary to this prediction and unlike both control groups, the patients’ ability to discriminate the target decreased more in the presence of peripheral compared to foveated distractors. Thus the attentional spotlight in simultanagnosia does not fall on foveated objects as previously assumed, but rather abnormally highlights the periphery. Furthermore, we found the same center-periphery gradient in the patients’ ability to recognize multiple objects. They detected multiple, but not single objects more accurately in the periphery than at fixation. These results suggest that an abnormal allocation of attention around the gaze can disrupt the grouping of individual objects into an integrated visual scene















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Seminar talk in the School of Psychology at the University of Leicester

SciencePosted by Daniela Balslev Fri, March 07, 2014 12:58:44

Thursday 27th March 2014 at 4pm, School of Psychology, University of Leicester

Eye position signals in spatial cognition

The straightforward sense of where things are belies the hard problem of aligning input from mobile sensory organs with one another and with the action space of the body. Without information about the rotation of the eyes within the head, for instance, it would be virtually impossible to match an unknown face and a voice in a crowd or to reach to visual targets without seeing the hand.

There are two main signals of eye position. The copy of the command sent to the extraocular muscles (corollary discharge) is predictive, therefore faster. The reafference from these muscles (proprioception) is slower, but more accurate. In my talk I will present evidence that these signals are used flexibly, depending on behavioral goals. Locating objects relative to the body, for instance to guide a movement, relies mainly on the fast signal, corollary discharge. In contrast, eye proprioception seems to be more important for perception, ie allocating attention in the body-centered space.







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Funding for PhD studentships

SciencePosted by Daniela Balslev Sun, November 17, 2013 18:35:33



Prospective PhD students who are interested to work with me may want to check out the studentships offered by the School of Psychology and Neuroscience at the University of St Andrews in open competition.
The deadline of application is normally in january/february with start in september.
Details of the application procedure in the previous round of application can be found here

If interested please email me your CV and a short paragraph that outlines a potential research project.

I would be happy to train the student to use transcranial magnetic stimulation and functional magnetic resonance imaging in healthy and patient populations to investigate how sensorimotor signals contribute to spatial cognition. The oculomotor command and the re-afferent input for the eye muscles are fundamental building blocks in the neural representations that support movement, attention or object recognition. The goal of my research is to understand how the brain represents space and how a breakdown in these representations in neurological patients can lead to disabilities such as optic ataxia, spatial neglect or simultanagnosia.

St Andrews has a strong vision group using a variety of techniques (including psychophysics, eye movements, EEG, fMRI, TMS, neuropsychology) to study the human visual system. Ours is a highly multidisciplinary group with members trained in biology, neuroscience, medicine, psychology, maths, physics and engineering. We welcome potential students from these and related disciplines.

















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PhD position opening

SciencePosted by Daniela Balslev Sat, November 16, 2013 15:34:56
The PhD position advertised below has now been filled. Welcome to Bobby Innes who will start in the lab in september 2014 ! Prospective graduate students interested to join us, please get in touch with a CV and a brief paragraph that describes a possible research project. Funding information can be found here

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I am advertising a BBSRC-funded PhD position. The project is at the interface between cognitive neuroscience and computational modelling and should be of interest to students not only in psychology or neuroscience, but also in computer science, physics, biology, engineering, maths, medicine and related disciplines. The student will be supervised by me and Tom Otto and will join a multidisciplinary team interested in Vision Science at St Andrews.





























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new paper accepted in J Neuroscience

SciencePosted by Daniela Balslev Tue, October 15, 2013 15:24:51
The paper "Role of somatosensory cortex in visuospatial attention" by Balslev, Odoj and Karnath has just been accepted for publication at J Neuroscience.

Abstract

The human somatosensory cortex (S1) is not among the brain areas usually associated with visuospatial attention. However, such a function can be presumed, given the recently identified eye proprioceptive input to S1 and the established links between gaze and attention. Here we investigated a rare patient with a focal lesion of the right postcentral gyrus that interferes with the processing of eye proprioception without affecting the ability to locate visual objects relative to her body or to execute eye movements. As a behavioural measure of spatial attention we recorded fixation time during visual search and reaction time for visual discrimination in lateral displays. In contrast to a group of age-matched controls, the patient showed a gradient in looking time and in visual sensitivity towards the midline. Because an attention bias in opposite direction, towards the ipsilesional space, occurs in patients with spatial neglect, in a second study we asked whether the incidental co-injury of S1 together with the neglect-typical perisylvian lesion leads to a milder neglect. A voxelwise lesion behaviour mapping (VLBM) analysis of a group of right hemisphere stroke patients supported this hypothesis. The effect of an isolated S1 lesion on visual exploration and visual sensitivity as well as the modulatory role of S1 in spatial neglect, suggest a role of this area in visuospatial attention. We hypothesize that the proprioceptive gaze signal in S1, whereas playing only a minor role in locating visual objects relative to the body, affects the allocation of attention in the visual space.

Funded by the Danish Medical Research Councils (DB). With thanks to RW for helping us conducting this study.

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