There’s an open-access paper by Fan and colleagues titled ‘Assessing the heritability of attentional networks’ which is available here. The researchers provide a background to the research in attention networks. For the purposes of this study the researchers are interested in three specific attentional networks
1. The orienting network which involves orientation towards a stimulus of interest. They detail some of the suspected neural correlates and associate this with the cholinergic system.
2. The executive network which is ‘resolving conflict between stimuli and responses’. The researchers identify some of the likely neural correlates and associate this network with dopamine.
3. The alerting network which ‘maintains the alert state’. Again the researchers identify the likely neural correlates and associate this network with noradrenaline.
They then provide a lot of good evidence to suggest that these networks can be associated with different mental illnesses and that there are good arguments for supposing that the properties of these networks should be highly heritable.
In their study design, the researchers have recruited monozygotic and dizygotic twins. In brief, the participants undertake neuropsychological tests which assess attentional responses. These are described in more detail in the materials and methods section. Dizygotic twin performances are then compared with those of monozygotic twins in order to better understand the genetic load of these networks.
One of the thoughts I had about this was the difficulty there is in reducing complex mental phenomena to simple models. This applies not just here but to many areas in the clinical neurosciences. Implicit in the models described above is that orienting responses are restricted in some way to a few regions in the brain and that there is a straightforward relationship with acetylcholine. Nevertheless a cursory examination of these assumptions reveals that these regions are interconnected with yet more regions. If you have a massively interconnected structure where is the justification for demarcating regions of function? Such justifications suggest a dichotomous function/non-function scenario whereas the truth might lie along the lines of a continuum with additional regions being recruited as necessary.
However such objections don’t offer a solution in place of the current approach. Indeed with this approach it is possible at least to get things wrong and it is through this act of getting things wrong that a better approximation to nature can be reached (although this might be another tenuous assumption). Nevertheless even if the entire model is invalid, the psychological phenomenon still remain valid but in the process a language has been developed. It is this language which is the important byproduct of the process because it enables the research community to formulate new more meaningful models and this specialised language would fit into what Kuhn describes as part of ‘normal science‘.
After the interesting build up in the paper, in their analysis the researchers suggest the study is underpowered and based on their calculations identify a suitable size for a replication study.
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