The work done in the laboratory concentrates on animal and human higher visual functions.
The main technics used for the animal experiments are standard acute and chronic electrophysiological methods, extracellular single cell recordings. There are two main streams of the animal experiments.
In
chronic cat experiments the properties of the anterior ectosylivan visual
area (AEV) of the temporal lobe is studied. AEV is an exclusively visual
area, involved in motion perception. Other chronic cat experiments focus
on another areae, situated along the suprasylvian sulcus (Br 21, a, b),
that seems to be involved in the object vision of the cats. Analogues of
the inferotemporal area of the macaque brain is sought.
In
chronic monkey experiments we study object vision in rhesus monkeys. Extracellular
single unit recordings are performed over the anterior parts of the inferior
temporal cortex, while the animals are performing behavioural tasks. Shape
invariant properties of the inferotemporal cells are tested, using complex
natural and geometrical stimuli depicted as photographs and line drawings.
In
human electrophysiological and psychophysical experiments (that are performed
in cooperation with the Opthalmological and Psychiatric Departments of
the University) the primary and late cognitive visual evoked potentials
are recorded in healthy human subjects as well as in different neurological
patients (schizophrenics, Parkinsonians and Alzheimer patients). The primary
positive component of the visual evoked potentials is strongly dominated
by physical parameters of the stimulus, such as spatial frequency, luminance
or contrast of the pattern. The late cognitive component of the human event-related
potential is a parietocentral positivity that occurs when a subject detects
an informative task-relevant stimulus. The amplitude of this component
depends on stimulus probability and its latency is affected by task difficulty
and the neurological status of the subjects.
In
standard human psychophysical experiments higher visual functions of the
ventral pathway are studied. These studies concentrate around two main
topics. First, the invariant properties of visual object recognition is
studied, using a simple visual discrimination task. Second, properties
of human categorical perception is studied.