High resolution, high field strength MRI studies of the mechanisms and architecture underlying human stereoscopic vision

Lead Research Organisation: University of Oxford
Department Name: Physiology Anatomy and Genetics

Abstract

Functional magnetic resonance imaging (fMRI) can be used to visualise activity in the brains of human subjects. When a region of the brain becomes active the cells begin to fire action potentials to communicate information. An increased flow of oxygen is required in that local region to fuel this activity. Since oxygenated (fresh) and de-oxygenated blood have different magnetic properties, it is possible to use the ratio of these two substances to measure changes in brain activity. The techniques used for looking at the human brain, both its function and its connections, are constantly evolving, allowing us to gain more and more information.
This project is designed to determine how we use our 2 eyes to see in depth. There are many pieces of information that can tell us where objects are in relation to each other, but if a slight difference is introduced between the images of the two eyes artificially, such as in ?Magic Eye? pictures, an object may ?jump? out without any other information available. Using stimuli that are similar to Magic Eye pictures we will investigate 3 main issues:
1) We will look in the normal population to see whether different areas of the brain are specialised for processing different stages of depth perception. We will also investigate whether the responses of the brain are related to how good people are at seeing depth.
2) Deficits in depth perception are common, as any misalignment of the two eyes during early childhood due to ?squint? or ?lazy eye? can prevent the development of binocular neurons; those sensitive to input from both eyes. Although these conditions can often be corrected surgically, not all children regain their binocular vision. We will investigate the neural responses in such subjects lacking binocular vision to examine how their brains process information differently from people with normal binocular vision.
3) The amount of detail that can be seen with fMRI depends on various factors, but an important one is the strength of the magnet used for the experiments. We are very fortunate in Oxford as we will have access to a very strong magnet that we will use to investigate the very fine organisation believed to underlie the perception of depth.

Technical Summary

We propose to use high resolution, high field-strength functional magnetic resonance imaging (fMRI) to determine how the human visual cortex processes binocular depth. Using 3-Tesla or 7-Tesla, state-of-the-art, scanning methods, we will image, at a much higher resolution than before, the organisation for binocular disparity in sub-compartments of human visual cortical areas.

Our brains can compute information about the depth of objects by exploiting the slightly different images on the retinas of the two eyes. However, the development of binocular vision can be disrupted in childhood, often leading to permanent visual deficits, typically amblyopia. Subjects with normal binocular vision show a link between the amount of neural activity and psychophysical performance in many visual cortical areas. Interestingly, however, our recent work has shown that the fMRI responses of lateral occipital areas LO-1 and LO-2 appear to be driven primarily by the disparity of the stimulus, regardless of the performance of the subject. Thus, these areas may have a pure stimulus-related signal, rather than a signal mingled with other factors, such as attention or task difficulty.

To investigate this hypothesis further, Part 1 aims (i) to use multivariate analysis to determine whether these areas can resolve different disparities within the stimulus and (ii) to correlate the levels of neural activation to disparity-defined stimuli with the ability of the subject to detect binocular depth. Comparisons across several of the multiple, independently-defined visual areas will indicate whether the neural activation of LO-1 & LO-2 is indeed tightly linked to the disparity stimulus alone.

One of our longer-term, strategic goals is to develop MRI into a tool for evaluating the efficacy of treatments for amblyopia. Part 2 of this project will measure the neural activity in two simple binocular experiments in patients with dysfunctional binocular vision. The patients will be classified according to the severity of their condition, allowing a correlation between neural activity and binocular performance.

Recent optical imaging studies have confirmed long-standing claims of a functional organisation for disparity within the identifiable compartments of cortical area V2 in non-human primates, suggesting the importance of depth processing in the visual system. This architecture has never been mapped functionally in humans, but should be within the reach of the new 7-Tesla scanner at FMRIB. Combined with the imaging of ocular dominance columns in V1, it will be possible to image compartments of cortical areas that may be altered in binocular dysfunction.

Publications

10 25 50
 
Description Research Grant
Amount £2,463,847 (GBP)
Funding ID MR/K014382/1 
Organisation Medical Research Council (MRC) 
Sector Public
Country United Kingdom
Start 03/2014 
End 03/2019
 
Description St John's College Scholarship
Amount £45,000 (GBP)
Organisation University of Oxford 
Sector Academic/University
Country United Kingdom
Start 09/2011 
End 09/2014
 
Description University of Pisa 
Organisation University of Pisa
Country Italy 
Sector Academic/University 
PI Contribution I hosted a postdoctoral research fellow to acquire data on our 7T scanner. We designed protocols and taught data acquisition and analysis.
Collaborator Contribution The postdoctoral fellow is funded by the collaborator
Impact 10.1109/IC3D48390.2019.8976001 10.1016/j.cub.2015.04.021
Start Year 2012
 
Description Breath workshop 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Members of the public attended session of talks on 'breath' to celebrate anniversary of death of John Radcliffe.

None currently, although links between arts, science and humanities was interesting.
Year(s) Of Engagement Activity 2014
 
Description Cafe Scientifique 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact 100 attendees at a Cafe Scientifique in which I spoke about my work on visual perception and depth perception.

Several participants got in touch to want to discover more about visual deficits.
Year(s) Of Engagement Activity 2012
 
Description Dorothy Hodgkin Legacy Talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Schools
Results and Impact Pupils (age 14/15) from 4 schools in the Royal Society Partner Schools program attended a series of talks on the research of several researchers.

Excellent feedback on how interesting it was to learn about the brain.
Year(s) Of Engagement Activity 2010
 
Description Down School project 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach Local
Primary Audience Schools
Results and Impact 30 pupils participated in a project to investigate the effects of sleep and diet on reaction times.

Considerable interest in applying to University within the participant group.
Year(s) Of Engagement Activity 2014
 
Description Museum Exhibition 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Type Of Presentation Workshop Facilitator
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact 2000 people came to an exhibition on 'Sleep on the Brain' at the Oxford University Museum of the History of Science

An A-level pupil approached me to undertake a Nuffield placement that she subsequently completed in the summer of 2013
Year(s) Of Engagement Activity 2013
 
Description Newsletter article 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Participants in your research and patient groups
Results and Impact Wrote article about research for the Micro- and Anophthalmia Children's Society.

None yet.
Year(s) Of Engagement Activity 2010
 
Description Open doors 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact As part of 'Oxford Open Doors' we invited members of the public to the scanning centre to watch someone being scanned and choose the experiments to be performed.

Considerable interest from many sectors of society.
Year(s) Of Engagement Activity 2014
 
Description Oxford Sparks Cartoon 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation Paper Presentation
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Was a scientific adviser on cartoon to explain how brain imaging works.

Many hits in first week
Year(s) Of Engagement Activity 2013
URL http://www.oxfordsparks.org/animations/mri
 
Description Phineas Gage talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact 300 members of the general public, patient groups and University members attended evening of talks and a film related to Phineas Gage.

None as yet
Year(s) Of Engagement Activity 2014
 
Description Primary school visits to MRI scanner 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Each year, around 120-150 primary school pupils visit the Wellcome Centre for Integrative Neuroimaging to experience a brain scan and interactive presentations from researchers.
Year(s) Of Engagement Activity 2011,2012,2013,2014,2015,2016,2017,2018,2019,2020
 
Description Radio Interviews 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact I participated in 3 radio interviews (Radio 4, Radio Berkshire and Radio Oxford) about visual perception.

Not yet known.
Year(s) Of Engagement Activity 2012
 
Description Royal Society Schools Show 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact Talk given to 8 groups of 100 school children over 4 days of Royal Society Summer Science Exhibition

Many questions from pupils after sessions
Year(s) Of Engagement Activity 2011
URL https://royalsociety.org/events/2011/human-brain/
 
Description School project - Wallingford 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach Local
Primary Audience Schools
Results and Impact I gave a talk on the brain to AS-level pupils in the 6th Form of Wallingford School. 15 of the top biology students then came to the FMRIB Centre to watch a brain scanning session and to learn about binocular and colour vision. In a final session, the pupils were taught how to analyse the data from the experiment.

Following this project, 2 pupils each spent 1 week doing work experience with me at the FMRIB Centre. A 3rd pupil would like to do an extended project during his gap year.
Year(s) Of Engagement Activity 2009
 
Description School visit 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Organised activities for Science week, spending time in 5 classrooms over the day (150 primary school pupils).

Am now known as the brain lady and children approach will questions from time to time.
Year(s) Of Engagement Activity 2010,2011
 
Description School visit London 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach Local
Primary Audience Schools
Results and Impact Session on evolution for 4 classes of primary school pupils. Questions on my own research fielded during the session.

Great interest in the human brain from all ages of pupil.
Year(s) Of Engagement Activity 2010
 
Description School visit, Oxford 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Session on depth perception for Foundation level pupils (age 4 or 5). Using 3D glasses for pictures and movies.

None yet, but likely from future visits.
Year(s) Of Engagement Activity 2010
 
Description Sunday Times article 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact 10 scientists funded by the Royal Society (including me) were photographed and interviewed for a the Sunday Times Magazine article on British Science.

Magazine only just published, outcomes not yet known, but useful to raise awareness of the general public.
Year(s) Of Engagement Activity 2010