Ron Kupers, Maurice Ptito Group – University of Copenhagen

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Ron Kupers, Maurice Ptito Group

Research

1. Cross-modal plasticity following sensory deprivation (Kupers-Ptito research group)

In our laboratory, we study cross-modal plasticity following the loss of a sensory input such as vision (blindness) or audition (deafness). We thereby use a combination of psychophysics, brain imaging techniques and transcranial magnetic stimulation in order to study the presence of compensatory plasticity and its underlying neural correlates. Do blind and deaf subjects compensate for their loss of vision by developing supranormal abilities in one of the remaining sensory domains? If so, what is the role of the occipital cortex in this compensatory plasticity? We have examined changes in olfactory, gustatory and thermal processing in congenitally blind subjects. Our studies revealed that whereas congenitally blind individuals perform better than sighted individuals for olfactory tasks, whereas they are worse in gustatory tasks. We are now studying the role of odours in social and emotional communication in blindness. Our studies on pain and temperature perception indicated that congenitally blind individuals are more sensitive to pain compared to normal subjects, and are better in discriminating non-painful heat stimuli.

We use in-vivo brain imaging methods to study the effects of sensory deprivation on the reorganization of the cortex. Our studies have shown that congenitally blind subjects show significant reductions in grey and white matter, not only along all the structures of the visual system but also in non-visual areas. Using diffusion-weighted magnetic resonance imaging (DWI), we are currently investigating changes in the microstructural integrity of the major fiber tracts that connect the visual cortex with other parts of the brain. We have now also started collecting data in subjects suffering from congenitally and acquired deafness in order to compare plasticity-related changes in the brain following two different forms of sensory loss.

One of the functions of the photoreceptors in the eyes is to provide light input to the suprachiasmatic nucleus in order to synchronize circadian rhythms to the solar light-dark cycle and prevent free-running. Considering the central role of light in entraining the circadian rhythm to a 24-h cycle, blind subjects are prone to disturbances in circadian rhythms. In collaboration with the Danish Center for Sleep Medicine, we are studying circadian rhythms, dream content, sleep macro –and microarchitecture, and sleep-related plasticity in congenital and late-onset blindness. In a first study, we showed that blindness considerably alters the sensory composition of dreams and that and that onset and duration of blindness thereby plays an important role. In addition, our data revealed that congenital blindness is associated with an increased occurrence of nightmares.

2. Cerebral correlates of pain perception (Kupers research group)

We study the cerebral correlates of pain processing in normal and pathological conditions. In collaboration with the University of Brussels (Belgium), we are using fMRI to study the mechanisms underlying the emotional conditioning of pain in normal volunteers. Nociceptive processing is not purely dictated by the sensory characteristics of the stimulus, but is the result of the interaction between the latter and the state of the nervous system at that particular time.

3. Primate Laboratory (Ptito endocannabinoid research group)

The monkey laboratory is situated at the Behavioral Science Foundation on the island of Saint Kitts (West Indies). We study the development and plasticity of the visual system in normal and alcoholic animals, using traditional anatomical and histological techniques such as tracer injections, immunohistochemistry, gene expression, etc. The ongoing projects concern

  1. the expression, localization and functional role of cannabinoid receptors in the visual system, from the retina up to the visual cortex. Our data indicate that the cannabinoid receptor CB1 is mainly expressed in the foveal cones, CB2 in the Müller cells, and GPR55 in the rods. We have proposed a model for the role of each of these cannabinoid receptors in vision that could explain the well-described visual effects of cannabis consumption. Outside the retina, we found that CB1 and CB2 receptors are localized in the optic nerve and dLGN. Next, we will measure the presence of cannabinoid receptors within the visual cortex;
  2. the negative effects of fetal alcohol exposure on the development of the retina and the ascending pathways to the cortex. Our preliminary results indicate that the cannabinoid receptor may contribute to the deleterious effects of alcohol on retinal development by interfering with axonal growth of ganglion cells.

4. Unconscious learning and emotional recognition in blindness (Carrara-Augustenborg research group)

Our research pioneers a novel areas of research: unconscious perception of auditory patterns in blindness. We focus on the neuroplasticity of implicit learning and explore the extents to which the inability to rely on visual information may correlate with blind individuals´ enhanced ability to detect auditory patterns and the emotions these convey implicitly.