Description
A spatial orientation and sensorimotor
integration facility, the SOSI lab, for both human subjects, features
real and virtual multi-sensory stimulation capabilities, coupled with human
motion control devices (sled and sled-rotators) and finger-hand-arm transducers.
The main equipment consists of:
- Real and virtual visual and auditory displays coupled with
motorized devices to control human self-motion.
- Human posturographic platforms coupled with visual displays
and/or dynamic support surface control.
- Multi-axis visual/auditory target motion device together with
eye-head-pointer transducers.
- Instrumented gloves that transduce 22 degrees of freedom in
joints of the fingers and wrist, together with mothion analysis, EMG and finger force
sensors.
- Large-scale visual display and psychophysical testing apparatus
for studying visuo-spatial cue processing in aging and Alzheimer's disease.
- Two-axis sled system coupled with a large visual display for
testing multi-sensory interactions in extrastriate visual cortical neurons.
New results obtained with the equipment:
- The vestibulo-ocular reflex (VOR) includes a semicircular-canal
driven reflex during angular motion (AVOR) and two otolith driven reflexes responding
to head tilt relative to gravity and to translational motion (LVORs). Tilt and
translation entail indistinguishable linear accelerations (Einstein's equivalency
principle), as reflected by ambiguity in LVOR responses.
- The translational LVOR behaves with high-pass characteristics,
but with an unprecedented high cutoff frequency of ~1 Hz. This explains why many other
studies of the LVOR have failed to record robust responses. The tilt LVOR, in contrast,
behaves with low-pass dynamics.
- Auditory targets are capable of producing smooth pursuit eye
movements (tracking) that resemble their visually-driven counterpart, only with lower
gain.
- Normal human subjects do not move their fingers independently
even when asked to move just one finger at a time. The thumb and index are the most
independent digits; the ring and middle fingers are the least independent.
- Single motor units in the human flexor digitorum profundus may
exert tension on multiple digits.
- Alzheimer's disease is associated with a selective impairment of
visual motion processing that is associated with spatial disorientation.
- Extrastriate visual cortical area MST integrates visual
and non-visual cues about self-movement with signals about pursuit eye movements
to form a veridical foundation for visual heading discrimination.