Brain structure, animal studies

The amygdala is perhaps the best-studied, and most strongly implicated, brain structure in anxiety and fear. Electrical stimulation of the amygdala produces fear-like behavioral and physiological responses in animals, and increases the suggestive experience of fear in human subjects. Additionally, amygdala stimulation leads to corticosterone secretion and HPA-axis activation in animals, probably via outputs to the hypothalamus and the bed nucleus of the stria terminalis. It has been suggested... 

Exposure to silver has been observed to affect the volume of hippocampal cell groups within the brain of animals. Several cell groups within the hippocampus (a well defined structure of the brain involved in some aspects of memory) are reduced in overall volume in rats exposed during their first 4 weeks of life to subcutaneously injected silver lactate (0.137 mg silver/kg/day) (Rungby et al. 1987). Unfortunately, the study is limited in that only one small region of the brain was examined. It is prudent to assume that similar effects would be observed in humans however, the implications of the altered volume of these cell groups are not known. 

For these studies, standard MRI scanners can be used to target the brain structures and to verify the BBBD. The only requirements are that the system has adequate space for the sonication system and high enough resolution to image animal brain. 

What are the brain structures or processes where variability accounts for variation in IQ If genetic contributions to inter-individual variation in IQ are in the order of 50% (Devlin et al 1997), which genes are important and what do they control Despite our expanding ability to non-invasively analyse the human brain we cannot count neurons or measure individual myelin sheath thickness. To do this requires studies of clinical populations coming to brain biopsy or autopsy. Work on these populations is slow, expensive, and subject to criticisms of the patient populations or variability due to uncontrollable post-mortem delay effects (Witelson McCulloch 1991). Animals do not have these difficulties. Further, unlike correlative inferential human studies, animal studies can attempt to be causal by actually manipulating the variables of interest. 

---