Basic Science
Conditions
Brief summary
How participants perceive the position of their own hand in various contexts will be examined. This will include changing the visual display to suggest the hand is in a slightly different position, and asking participants to indicate where they think it is by pointing with their other hand.
Detailed description
Hand position can be estimated visually, from an image on the retina, and proprioceptively, from sensors in the joints, muscles, and skin. The brain is thought to weight and combine available sensory estimates to form an integrated multisensory estimate. Inherent in this process is the capacity to realign one or both sensory estimates when they become spatially mismatched, as when washing dishes with the hands immersed in water, which refracts light. It is generally assumed that if a person knows about the sensory mismatch somehow, the realignment will not occur. This assumption will be tested in two experiments by giving people this information in different ways. Expt. A: Conscious awareness of the mismatch will be presented in different ways, or absent. Expt. B: Movement error feedback will be presented in different ways, or absent.
Interventions
BEHAVIORALExplanatory diagram
Participant is told there will be a mismatch between their target finger and the visual indicator of target finger position. They will be shown a diagram explaining this.
BEHAVIORALDirect vision
Foamboard under mirror removed, making the mirror see-through and the hand directly visible. Mismatch between target hand and visual indicator will be directly visible.
BEHAVIORALMovement feedback, target hand
After the participant points at each target, a cursor indicating final pointing position will be displayed briefly. The visual indicator of the target hand will be displaced.
BEHAVIORALMovement feedback, pointing hand
After the participant points at each target, a cursor indicating final pointing position will be displayed briefly. The visual indicator of the target hand will not change, but the cursor indicating pointing hand position will change.
BEHAVIORALNo movement feedback
The visual indicator of the target hand will be displaced, but there will be no cursor to indicate the pointing hand's position.
BEHAVIORALAttend to the targets
Participants will not be told anything about the visuo-proprioceptive mismatch. Instead, they will be asked simply to attend to the target positions.
Sponsors
Indiana University
National Institute of Neurological Disorders and Stroke (NINDS)
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
18 Years to 45 Years
Healthy volunteers
Yes
Inclusion criteria
* Between the ages of 18-45 years old * Right-handed. * Covid has been found to have neurological effects in some people, but mostly the effects on sensorimotor control and neurophysiology are unknown. So we will only include individuals who report being free of Covid symptoms in week preceding testing.
Exclusion criteria
* Past or present history of seizure, stroke, any brain or peripheral nerve disease, severe head trauma, or spinal cord surgery. * Learning or attention conditions such as ADHD. * Orthopedic or pain conditions, or a history of seriously injured bones, joints or muscles in either arm. * Lack of normal or corrected-to-normal vision.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Realignment | 1 day | Measured by comparing where the subject points on a touchscreen when indicating perceived position of visual and proprioceptive targets early vs. late in the behavioral task. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Visuo-proprioceptive weighting | 1 day | The degree to which participant relies on vision vs. proprioception when both are available. Measured by comparing where the subject points on a touchscreen when indicating perceived position of visual vs. proprioceptive targets. |
| Target estimation variance | 1 day. | Variance with which participant estimate visual and proprioceptive target positions. Computed from where subjects point at targets on a touchscreen. |
Countries
United States
Contacts
PRINCIPAL_INVESTIGATORDavid Koceja, PhD
Indiana University, Bloomington
Outcome results
None listed