Effects of developmental alcohol exposure on sensory processing
Alexandre Medina, Associate Professor, Department of Pediatrics, University of Maryland, School of Medicine. Baltimore, USA.
Fetal alcohol spectrum disorders (FASD) are caused by gestational alcohol exposure and is the most common cause of preventable mental disability in the world. Recent epidemiological studies in the US, UK and Canada indicate a prevalence of 1-7% of all births. Children with FASD often present sensory alterations such as aversion to multiple sensory stimuli presented at the same time, attention deficits, poor visual-motor integration, delayed auditory processing and hypersensitivity to tactile stimulation. There is growing evidence supporting the idea that these problems in dealing with sensory processing give rise to social problems and learning deficits.
Sensory integration problems have long been associated with learning disabilities. In fact, it has been shown that performance in a multisensory integration task correlates with scores in a comprehensive IQ test in school age children. Furthermore, impaired multisensory processing has been implicated in the development of ADHD, schizophrenia, dyslexia, autism, and other poor cognitive outcomes.
Multisensory integration (MSI) can be seen at neuronal level, when the combination of stimulus from two or more sensory modalities leads to either facilitation or suppression of neuronal responses. It is thought that crossmodal facilitation can facilitate cognitive processes by increasing the speed and accuracy of perception and by improving attention. This is important not only during active learning tasks but is also crucial for the acquisition of intellectual abilities in school age children.
Animal models have been crucial to understand MSI and neuronal crossmodal facilitation and depression have been observed in mice, cats, ferrets and non-human primates. In the ferret, the rostral posterior parietal cortex (PPr) is a multisensory area that contains neurons activated by both visual and tactile stimulation.
Our overarching hypothesis is that gestational alcohol exposure disrupts MSI, reducing perception of important stimuli and contribute to cognitive and attention deficits seen in FASD. During my talk I will present recent studies from my lab testing the prediction that exposure to alcohol during the third trimester equivalent of human gestation impairs visual- tactile crossmodal facilitation in ferret PPr.