Introduction to Issues in Neuropsychology

1. Sam Hutton Introduction to Issues in Neuropsychology • Aims and Objectives By the end of this lecture you will have learned: • An overview of the course structure, content and requirements • A definition of cognitive neuropsychology • The main aims of cognitive neuropsychology • The core assumptions relevant to cognitive neuropsychology and their implications • Required Reading • Parkin, Ch1 or E&Y, Ch1.

2. Sam Hutton Issues in Neuropsychology • Lecturers: Sam Hutton & Brendan Weekes • Contact hours: SH - Monday 10:30-12:00 • Course Text: Parkin, A. (1996). An Introduction to Cognitive Neuropsychology. • Course Website: http://www.biols.susx.ac.uk/ugteach/cws/iin/ • Course structure:3 Lectures a week, 1 Seminar a fortnight

3. Sam Hutton Timetable

4. Sam Hutton Cognitive Neuropsychology • What is it? Cognitive Psychology - the study of mental processes needed for everyday life. Based on an analogy between the mind and the digital computer - the information processing approach: Mental Abilities = Information Processing Assumptions: The mind is a general purpose “symbol-processing” system - symbols are acted on by processes Cognitive processes take time - RT predictions

5. Sam Hutton Cognitive Neuropsychology • What is it? Cognitive Psychology - the study of mental processes needed for everyday life. Based on an analogy between the mind and the digital computer - the information processing approach: Mental Abilities = Information Processing Assumptions: The mind is a limited capacity processor The symbol system and its processes depend on a neural substrate

6. Sam Hutton Cognitive Neuropsychology Neuropsychology - the study of the relationship between the brain and behaviour Cognitive Neuropsychology - Can be thought of as a specific discipline within cognitive psychology "Neuropsychology is cognitive to the extent that it purports to clarify the mechanisms of cognitive functions such as thinking, reading, writing, speaking, recognising, or remembering, using evidence from neuropathology" (Campbell, 1987).

7. Sam Hutton Relation to Other Disciplines • Cognitive science • develops computational models of cognition often to simulate the results from experiments. • Experimental cognitive psychology • empirical, behavioural data from controlled studies of normal subjects. • Cognitive neuropsychology • studies of brain damaged patients. • Cognitive neuropsychiatry • studies of patients with psychiatric disorders • Cognitive neuroscience • Neural basis of behaviour in animals - often maps neural activity to function • Behavioural Neurology • Uses data concerning anatomy and physiology of CNS to guide interpretations of disordered behaviour due to neural damage

8. Sam Hutton Cognitive Neuropsychology "In any well-made machine one is ignorant of the working of most of the parts - the better they work, the less we are conscious of them….it is only a fault which draws attention to the existence of a mechanism at all" (Craik, 1943) Cognitive Neuropsychology has some complex assumptions in addition to those of cognitive psychology

9. Sam Hutton Cognitive Neuropsychology What can we conclude about its workings?

10. Sam Hutton Aims of Cognitive Neuropsychology 1. Model confirmation / development • According to Ellis and Young, cognitive neuropsychologists • …explain patterns of impaired and intact cognitive performance seen in brain injured patients in terms of damage to one or more of the components of a theory or model of normal cognitive functioning • …draw conclusions about normal, intact cognitive processes from the patterns of impaired and intact capabilities seen in brain-injured patients • These two approaches are obviously linked, but differ in emphasis.

11. Sam Hutton Aims of Cognitive Neuropsychology 2. Cognitive localisation - • The attempt to specify specific areas of the brain as being involved in certain processes - some researchers NEVER do this (Ultra or Radical CNs) - others talk about it but know that it is a separate issue from the cognitive theories themselves - cognitive neuroscientists (e.g. Damasio / Goldman-Rakic) are particularly concerned with this and use data from patients, NCs, animal studies, molecular studies etc.. Theoretical vs Anatomical paradigms: Mackay (2001)

12. Sam Hutton Cognitive Neuropsychology Assumptions: Modularity - Mental life is orchestrated by multiple cognitive processors or modules Neurological specificity (isomorphism) - there is a correspondence between the organisation of the mind and the organisation of the brain (both lead to locality assumption) Transparency - observable behaviour will indicate which module is dysfunctional Subtractivity - Performance reflects total cognitive system minus the impaired module(s) - Plasticity - adaptation??? Universality - There are no individual differences in the organisation of cognitive modules

13. Sam Hutton Assumptions in Cognitive Neuropsychology • These are the topics of considerable debate • The debates are very complex! (see extended reading list for some examples) • These asumptions have very important implications for the methodologies used in cognitive neuropsychology (e.g single case vs group studies) and the inferences which cognitive neuropsychologists can draw from their data

14. Sam Hutton Assumption of Modularity Marr (1982) - Principle of Modular Design - “any large computation should be split up into a collection of small, nearly independent, specialized subprocesses” • Fodor (1983) - Modules are: • Domain specific • Innately specified • Informationally encapsulated • Fast • Hardwired (neurally specific) • Autonomous • Not assembled • Operation is mandatory

15. Sam Hutton Assumption of Modularity • Modularity in a strictly Fodorian sense causes problems for cognitive neuropsychology:- • Reading is clearly not innate • Not all cognitive modules appear mandatory (e.g.Recognition may be mandatory but is name recall?) • What about top-down processing? • Fodor also argued that only input (and possibly output) processes are modular • Most cognitive psychologists assume that “central” processes (e.g. reasoning, decision making) are also modular to some extent.

16. Sam Hutton Module = “A cognitive system whose application is domain specific” Domain specific = responds to inputs only of a particular class Assumption of Modularity Neo-Fodorian account of modularity (Coltheart, 1999) The other Fodorian criteria are not necessary features of modules. Whether or not a module possesses any of these features becomes an interesting empirical question Assumption of modularity is linked with assumption of locality (Farah, 1994) and logic of double dissociation

17. Sam Hutton Assumption of Isomorphism • It is possible to have functional modularity but not anatomical modularity • E.g cognitive modules may be distributed across wide areas of cortex • This would imply that any brain damage ought to impair a large number of modules • The fact that so many patients exist with highly selective disorders suggest that the assumption is tenable.

18. Sam Hutton Assumptions of Transparency/Subtractivity • Caramazza’s use of the term transparency is slightly more specific than most, equivalent to the subtractivity assumption as used by Shallice… • The cognitive system of the brain damaged subject is the same as that of a normal subject apart from a “local” modification • E.g brain damage does not result in the de novo creation of cognitive modules resulting in a cognitive system which is uninterpretable in terms of models of normal systems.

19. Sam Hutton Assumption of Universality • This assumption is crucial for any group studies in cognitive science • Allows us to consider the average performance of a group of individuals to be representative of any individual in the population from which the group was drawn.