A large proportion of subjects with autism exhibit seizure disorders and epilepsy. This co morbidity has been reported to be in the range of 30-40%. Epilepsy and abnormal EEG patterns occur at a significantly higher rate in individuals in the more impaired range of the autism spectrum. Seizures in the autistic population often include complex partial seizures involving the temporal lobe. The limbic network supporting these seizures is composed of the amygdala, hippocampus, medio-dorsal thalamus, piriform, rhinal, and orbitofrontal cortices. Recurrent and/or prolonged complex partial seizures alter the functional connectivity of this network in a manner that can impact both cognitive function and socio-emotional regulation. Importantly, this is the same network implicated in autistic pathophysiology and therefore these seizures may pose the greatest risk for adverse psychiatric outcomes in this population. Dysfunction (often in the absence of structural abnormalities) in the network anchored in the amygdala, and interconnected with the orbital frontal cortex, has been found in many cases of autism. This dysfunction is likely to be exacerbated by the aberrant plasticity induced in response to repeated seizure discharge. The goal of this application is to determine if a history of repeated seizure activity changes the responsiveness of this network and whether it predisposes this network to amygdala-mediated behavioral disturbances. Our recent findings showed that reversible manipulations of the GABAA receptors within the basolateral amygdala (BLA) by focal intracerebral infusions of GABAA receptor agonists or antagonists resulted in profound changes in social interactions and reward evaluation in nonhuman primates.
The Specific Aims will determine whether a history of complex partial seizures, focally-evoked from the piriform cortex in one hemisphere, result in an increased vulnerability to disinhibition within BLA in nonhuman primates. This shift in sensitivity will be probed by evaluating specific behavioral responses to focal manipulations of GABAA transmission within BLA: Social interactions (Aim 1), reinforcer devaluation (Aim 2), and emotional conditioning (Aim 3). The studies will address a recognized comorbidity, not yet studied in pre-clinical animal models, for which clinical studies cannot sort out the extent to which seizures may exacerbate the autistic symptomatology. The combination of co-investigators provides a unique blend of expertise in experimental epilepsy models, nonhuman primate models of socio-emotional disturbances, and neural substrates of human disorders of affect and psychopathy. The team is ideally suited to approach the analysis of comorbidity of seizures and autistic-like symptoms evoked from amygdala and to permit a translationally meaningful analysis of the animal data. ? ? ?
| Forcelli, Patrick A; DesJardin, Jacqueline T; West, Elizabeth A et al. (2016) Amygdala selectively modulates defensive responses evoked from the superior colliculus in non-human primates. Soc Cogn Affect Neurosci 11:2009-2019 |
