Trends in Cognitive Sciences
Development itself is the key to understanding developmental disorders
Section snippets
The implications for developmental disorders
The neuroconstructivist modification in perspective crucially influences the way in which atypical development is considered. In this approach, the deletion, reduplication or mispositioning of genes will be expected to subtly change the course of developmental pathways, with stronger effects on some outcomes and weaker effects on others. A totally specific disorder will, ex hypothesis, be extremely unlikely, thereby changing the focus of research in pathology. Rather than solely aiming to
Are some developmental disorders truly specific?
Despite the arguments in the previous section, some developmental disorders (e.g. autism18, 19, Asperger syndrome[20], dyslexia[21], Turner's syndrome[22], Specific Language Impairment[14]) appear at first sight to involve very specific deficits at the cognitive level. Autism, for example, is argued to be the result of impairment of the domain-specific mechanism of metarepresentation, dedicated solely to the processing of social stimuli10, 19—a deficit in the so-called `theory-of-mind' module.
Conclusions
One of the major problems with very specific accounts of developmental disorders of higher-level cognition is that so far no gene (or set of genes) has been identified that is expressed solely in a specific region of neocortex (see Ref. [30]for discussion). Yet, such theories claim that neocortex is pre-specified for functions such as theory of mind or language and that this is why they can dissociate in adulthood. This is the basis for most brain imaging studies. Some authors go as far as
Outstanding questions
- •
Some argue that evolution has provided the human cortex with increasingly detailed pre-specification prior to ontogenetic development. To what extent can the ontogenetic data be accounted for in terms of evolution selecting for less specific factors, such as increased neocortical plasticity and a greater range of learning mechanisms, to ensure adaptive outcomes rather than prior knowledge? Is it more useful to entertain the possibility that the highest level of evolution is to pre-specify
Acknowledgements
I should like to thank Mike Anderson, Susan Carey, Mark Johnson and Steven Rose, as well as the anonymous reviewers, for comments on an earlier version of this paper.
References (62)
Language deficits and genetic factors
Trends Cognit. Sci.
(1997)Canonical linking rules: forward versus reverse linking in normally developing and specifically language-impaired children
Cognition
(1994)- et al.
Neuronal models of cognitive functions
Cognition
(1989) - et al.
Simultaneous attention in the two visual hemifields and interhemispheric integration: a developmental finding on 20–26 month-old infants
Neuropsychologia
(1997) - et al.
Separate visual pathways for perception and action
Trends Neurosci.
(1992) LIM-kinase1 hemizygosity implicated in impaired visuospatial constructive cognition
Cell
(1996)- Gottlieb, G. (1992) Individual Development and Evolution: The Genesis of Novel Behavior, Oxford University...
The child's trigger experience: degree–0 learnability
Behav. Brain Sci.
(1989)- Pinker, S. (1994) The Language Instinct, Harmondsworth,...
The grammatical characterisation of developmental dysphasia
Linguistics
(1989)