Introduction to Neuropsychology For Psychiatry Residents Vaughan Bell
Course Outline • Introduction to neuropsychology • Introduction to neuropsychological evaluation • Referrals, reports and interpretation • Evaluation of psychiatric patients
What is Neuropsychology • Neuropsychology is the science of how the structure and function of the brain relates to psychological processes. • As a basic science it tries to understand these links experimentally. • As a clinical science it aims to understand how specific impairments relate to impaired brain mechanisms, or vice versa. • In neuropsychology, these two aims are strongly linked.
Phineas Gage • A railroad worker in Vermont, known for his good character and responsible attitude. • Suffered an injury in 1848 where a tamping iron was shot through his head when setting gunpowder to break rocks. • He did not lose consciousness and he walked home. • He was later seen by Dr Harlow who wrote up his case.
Effect on Gage Dr Harlow reported: “He is fitful, irreverent, indulging at times in the grossest profanity… capricious and vacillating, devising many plans of future operation, which are no sooner arranged than they are abandoned.”
Link to Function • This was some of the first evidence that damage to specific areas of the brain could affect personality and behaviour. • Later Paul Broca’s autopsy on a patient with expressive aphasia found a specific lesion in the left frontal lobe, now known as Broca’s area. • This suggested language was not single function and could be linked to certain brain circuits.
Modern Neuropsychology • Contemporary neuropsychology uses a variety of techniques to understand mind – brain links. • Neuroimaging • Computational modelling • Experiments on healthy participants • Lesions studies • Studies on psychiatric disorders
Lesion Studies • Understanding how brain damage affects human abilities is still the most powerful tool in neuropsychology. • One of the key techniques in both research and clinical work is the dissociation - a difference, break or uneven performance on tasks. • A dissociation between patients suggests that the task is not controlled by a single cognitive process. • A dissociation within a patient suggests difficulties in specific abilities.
Dissociations • In this example each patient had a single dissociation between one ability – object perception – and another – face perception. • Considering both patients, there is a double dissociation – so we know they rely on different brain processes.
Dissociations • The double dissociation is a scientific tool that helps us understand mind and brain function. • In a clinical patient, we can link deficits to what we know about neuropsychology… • …to understand what has gone wrong.
Early Visual Perception Deficits • Damage to the early visual system will produce things such as: • Visual field deficits • Orienting difficulties • Impairments in shape, form or size discrimination. • Colour blindness • Motion blindness
Dorsal Stream The ‘where’ or ‘how’ stream Ventral Stream The ‘what’ stream
Associative Agnosia Associative Patient HJA (Riddoch and Humphreys, 1987) Copying without Naming
Apperceptive Agnosia Original Patient Copy Apperceptive Patient HC (Sparr et al., 1991) Impaired Copying of Simple Shapes
High Level Vis Perception Deficits • Prosopagnosia – selective impairment in perceiving faces. • Simultanagnosia – difficulty perceiving more than one object. • Dorsal type – can identify an object but can’t locate them in space. • Ventral type – can perceive more than one object, but can only identify one at a time.
Some Memory Systems • Working memory – less than 30s, manipulated by executive system. • Long-term memory • Semantic memory – facts • Episodic memory – events • Alternative long-term memory classification • Declarative memory – consciously describable information • Implicit – unconscious skill learning, conditioning etc
Memory Functions • Encoding – perception, selection and transfer of information into memory. • Storage – maintenance of information in a retrievable state. • Retrieval – reactivating stored information for conscious retrieval or unconscious use during task performance.
Key Memory Circuits Hippocampi HM (1926 – 2008) Including a circuit with the fornix, mamillary bodies and septal nuclei.
Working Memory Problems • Can be caused by damage to visual or auditory storage. • But more usually due to executive system damage which affects how well we use these stores. • Double dissociation between storage and manipulation of information I working memory (Mintzer and Griffiths, 2007): • Lorazepam – manipulation impairment • Scopolamine – storage impairment
Long-term Memory Problems • Amnesia for episodic memories: • Antereograde – inability to encode new information • Retrograde – loss of pre-injury information, most recent memories most likely to be affected. • Semantic memory impairments: • Semantic dementia – loss of words and meaning. • Selective impairments – e.g. living vs non-living things.
Long-term Memory Problems • Transient amnesias: • Post-traumatic amnesia – correlates with extent of injury • Transient global amnesia – sudden, dense amnesia that resolves within hours. • Transient epileptic amnesia – similar, shorter duration and associated with clear seizure activity. • Psychogenic amnesia – syndrome of ‘hysteria’, often pure retrograde amnesia, and can include loss of identity and wandering (‘fugue state’).
What is the Executive System? • Mainly concerned with the co-ordination of other cognitive resources. • e.g. the use of attention, organisation of actions, inhibition of responses, monitoring (metacognition). • It is a dynamic, ‘online’ system, that may only fully engage some aspects in real world situations. • e.g. Saver and Damasio’s (1991) patient EVR displayed severe day-to-day executive problems but passed standard tests of executive function.
What is the Executive System? • So it is particularly involved in handling new, novel or potentially risky situations. • Norman and Shallice (1980) outline five types of situation where routine activation would not be sufficient.
Norman and Shallice (1980) • Those that involve planning or decision making. • Those that involve error correction or troubleshooting. • Situations where responses are not well-learned or contain novel action sequences. • Dangerous or difficult situations. • Situations which require the overcoming of strong habitual response or resisting temptation.
Neuroanatomy • Most associated with the prefrontal cortex although there is increasing evidence that parietal interactions are important (Collette et al., 2006)
Dysexecutive Syndrome • Damage can result in: • Problems with memory (e.g. working or episodic memory) • Problems with affect and social judgment (inappropriateness, emotional lability / blunting, social perception, theory of mind) • Problems with abstract thinking and intentions (planning, understanding rules, cognitive flexibility, inhibition)
Attention • Typically divided into three main types (Posner and Petersen, 1990): • Spatial attention – distinguish and detect sources of information in space • Selective or focused attention – focus in / block out certain sources. • Arousal / sustained attention – maintain focus
Neglect • Hemi-spatial neglect is one such disorder which particularly occurs after right parietal damage. Severe neglect Mild neglect From Vallar (1993)
Line Bisection • When asked to mark the centre point of a line, patients mark to the right.
Language • Language involves: • Production (e.g. speaking, writing, syntax, articulation) • Comprehension (e.g. reading, listening, syntax) • Knowledge (e.g. names, words)
Wernicke’s area Broca’s area
Arcuate fascilulus From Rodrido et al. (2007)
Speech Problems • A few of the many aphasias: • Broca’s aphasia (normal comprehension, non-fluent speech). • Wernicke’s aphasia (impaired comprehension, fluent but meaningless) • Conduction aphasia (normal comprehension, fluent speech, wrong words and poor repetition) • …and many others.
Reading / Writing Problems • Dyslexias and agraphias are broken down into two main types: • Peripheral dyslexia – problems with word or letter perception. • Central dyslexia – problems with the semantics or syntax of language • Peripheral agraphia – problems with motor control. • Central agraphia - problems with the semantics or syntax of language • …and various combinations.