Chapter 4

Flashcards

Answers to the study questions in the book

The following clues and hints about the study questions for the second edition of Neuropsychology: From Theory to Practice should be read only after attempting independently to answer the question. Problem-solving a question is the best way of learning.

This is the type of question that can be argued over by theoreticians towards competing views and sometimes without coming to any firm conclusion. However, it does refer to an issue concerning the validity of research in a number of areas of neuropsychology.

The argument for using a healthy group of participants contains the view that this will reveal the structure of executive functioning without the encumbrance of a damaged brain. This position is based on the understanding that changes associated with brain recovery such as plasticity and structural changes associated with behavioural and cognitive compensation result in research that is not representative of the healthy brain. An alternative is to use a factor analysis on brain-damaged patients with the hope that the performance of such patients will realise a coalescence of qualities that define executive dysfunction further with the understanding that this is more difficult to realise when using healthy subjects. However, there are epistemological difficulties with any factor analytic approach whether healthy or brain-damaged patients are used. Such an approach supposes a priori that the tests measure executive functioning in the first place. This viewpoint assumes that the true nature of executive dysfunction can be realised when we study patients with executive dysfunction but such an argument is, of course, circuitous. The approach to use patients that are brain-damaged with executive function assumes that you have already a knowledge of what constitutes executive dysfunction. Also, studies that have set out to do this have shown little relationship between tests of "executive functioning". This means that executive functioning is probably a fractionated concept as is argued by others and in this text.

A third approach has been taken which has some attraction for the author. This approach is to be guided by past theory and clinical experience and identify an everyday behaviour that is clearly handicapping for the patient. To study such everyday behaviour is reasonable because it is a clinical issue that will not go away. Having identified a group of patients that show such behaviour the next step is to give the patients a set of tests with the hope that one or more might predict such behaviour. Such studies may further seek to design a test that reflects such behaviour. There is then an approach to see which traditional tests and which of the new tests predict the disorganised behaviour. Sometimes this has resulted in new tests that simulate an environment that typically tests such behaviour. The relationship with the patients' clinically recognised everyday behaviour provides a standard for such tests and many have been found wanting and their clinical usefulness questioned. Hopefully, the student will martial their own arguemnts on what is a critical debate within neuropsychology.

This question concerns the section research approaches and has implications for the rationale and frailties of the research referred to in this text. The student would be advised to set out the advantages and disadvantages of each approach to research.

This is a difficult question but as the author of a relatively comprehensive text it is easy to see that over the years overlaps between supposedly separate functions have occurred. For example, attention has an executive component that also seems to exist in working memory. It is also difficult to distuinguish between attention and perception with modern research endeavours. Of course, we humans have proposed these labels and although they are intuitive, such well-defined divisions are unlikely to exist in reality. The brain just gets on with adapting to the environment in any way it can. These conceptual categories are a way of looking at things that has determined fields of research that have extended and prolonged support for such distinctions.

In one sense this progression in understanding of overlaps between functions is not so surprising if one considers that the early texts in cognitive psychology which provided the guiding seeds for neuropsychological theoretical endeavour were based on a far smaller research base than is available now. For example, in the 1960s and 1970s the distinction between attention and memory was obvious, helpful and clearer than it is now.

One indication of these overlaps between functions that were hitherto seen as being relatively independent comes from imaging studies that show considerable overlap of activation between tasks that were ostensibly seen to be functionally separate. This has led to the proposal by some that measures of different "functions" have more overlap or at least similar overlap to measures that are supposedly measuring the same function. The overlap of supposedly different functions is a persuasive argument when viewing these imaging studies and is in some way in keeping with Luria's approach that there are basic units that work in concert as a requirement for many different functions e.g. memory, perception, attention. For example, most tasks require a certain level of arousal, the encoding of information and some level of cognitive and behavioural organisation.

However, this viewpoint in its extreme has limitations in the author's opinion. While most tasks require the interaction of a number of brain areas, clinical experience reveals that the brain also has a number of speciality areas. Take, for example, the patient who is well organised and has a huge number of strategies to compensate for their amnesia; or the patient who is disorganised but nevertheless achieves normally in structured tests of memory; or the patient who has perceptual difficulties but is otherwise relatively intact. These patients bear witness that while there may be sub-functions that are commonly used in most tasks there is also some considerable specialisation.

The polar frontal areas are seen to be involved in self-monitoring of behaviour and prospective memory. Therefore any goal-directed behaviour will be undermined when there is damage to this area. The patient may not remind themselves in a timely manner that they must buy certain items and will be easily distracted by advertisements and salient products. Also, they may buy a large number of products they do not actually need because they become easily distracted. Their shopping will also be haphazard and without a plan. Heavy items are picked up first and aisles are not approached in any order. The patient may take an inordinant amount of time aimlessly walking around, but also might take a series of short trips only returning to the car to find that they need to return to the supermarket.

Try and describe this kind of behaviour in another context.

Dopamine is the main neurotransmitter of a collection of subcortical nuclei (grey matter) referred to as the basal ganglia. The action of dopamine is mainly inhibitory and the complex circuits of the basal ganglia have a controlling influence on motor areas via the thalamus. However, further circuits influence and control circuits from the prefrontal cortex. The putamen, as part of the basal ganglia, is most obviously involved with movement and some Huntington patients appear to be disinhibited in their choreic (writhing) movements. Parkinson patients also have movement problems and some of these provide evidence of akinesia arrest of movement and bradykinesia slowed movements being inhibited movement. Of greater interest in terms of the present discussion is the function of the caudate nucleus (also part of the basal ganglia). The caudate nucleus projects information from the perfrontal cortex and damage to this area is associated with the executive signs that are especially associated with advanced signs of Huntington's disease. Such patients have difficulty in planning mazes and show signs of poor organisation of memory recall and copying spatial constructions. These patients improve when they are provided with a structure which reduces their need to initiate strategies of organisation.

There are dorsolateral and orbitofrontal circuits that run through the basal ganglia that are presumed to influence executive cognition and emotional control, respectively. When dopamine levels are unbalanced and low then such circuits will be undermined, although in Parkinson's disease to a lesser extent. The difficulty with the treatment of dopamine is that too much dopamine in the system may be as hazadous as too little. Doctors are often involved in a guessing game as the dosage requirements of a patient are difficult to judge. This is not just because high doses of dopamine cause side effects such as tics and even psychotic symptoms e.g. temporary hallucinations, there are also optimal levels for different tests of executive function. These factors also provide uncertainties for research in this area. A more detailed answer may be given when a later section is read that deals with the relationship between dopamine and apathy in Huntington's disease.

The domain specificity model argues the extensions of the what pathway and the where action pathway to the prefrontal cortex. These provide an executive component that serve certain types of language-related visual/auditory processing for the ventral what pathway and attentional/visuo-spatial processing for the dorsal where action pathway.

In contrast, the hierarchical model proposes that the more rostral prefrontal processing is associated with more complex and abstract processing. Combining these two models allows a synergy between the need to identify complex control processes within domains of processing. It would be a useful exercise for the student to draw a box and arrow diagram that satisfies these two demands. This would promote a feeling of how modelling is likely to progress in the future.

As predicted by the hierarchical model of executive functioning areas 10 and 9 are at the executive apex, being involved in the most abstract and monitoring role. Also in keeping with this role there are connections with the neighbouring areas of the prefrontal cortex. In this way the area has access to the processing attributed to the dorsolateral prefrontal cortex. The dorsolateral prefrontal cortex is clearly important in maintaining information in mind or working memory. Such information may be strategic: in order to replace this car lock I should first photograph it with my phone so that I know how to reconnect it. Such information may be placed in primary consciousness at the time I am thinking about this strategy (e.g. area 46). But there will also be an overview of what I am doing and knowledge of my goal. If, for example, I see an interesting magazine in the front car seat, I might pick it up and read it for a while, but afterwards I will recall my overall purpose for being at my car and return to my replacing the lock task (area 10). So it makes sense to have interconnections between these two areas.

From studies with other primates it has been realised additionally that areas 10 and 9 have direct connections with the premotor area which is less obviously coped with by the hierarchical model and that area 10 may also have a teleological role. This would allow this area some direct and positive role for action that might be called upon in some circumstances. Before reading on the student might wish to think what this might be.

As a speculation and if one believes that such connections have evolved as being important to our survival, then in some situations there might be a goal to keeping safe while carrying out some food foraging. Being ready for predators over time might be an overall goal despite working memory being taken up with collecting strategy activities. Direct connections of area 10 with motor areas mean the priority goal of keeping safe with immediate action and without further prefrontal processing. The idea of area 10 allowing multitasking and prospective memory is discussed by Paul Burgess and others.

The rationale for connections between area 10 with other areas has been discussed above but it should be noted that area 10, unlike the dorsolateral and ventrolateral areas, has its main connectivity with neighbouring PFC areas. Areas 10/9 do not have a proliferation of connections with the association areas or tertiary sensory areas that are responsible for analysing incoming information. In other words area 10 appears to be in a good position to be an overseer or supervisor of the goals of mental activity rather than have direct involvement in ongoing cognitive activity itself.

Cells within the lateral prefrontal cortex have been found that maintain their representative activity for a period after a percept has disappeared. The mechanism for maintaining information within consciousness and within working memory are complex because they require both attention and retrieval of information from memory.

Both the ventrolateral and the dorsolateral prefrontal cortex (PFC) have connections with areas associated with memory retrieval (medial temporal lobe which include cortical areas with connections to the hippocampus). The most obvious role of the ventrolateral area when considering executive function is the role in the selection of information and retrieval of memories while the most obvious role of the dorsolateral area is maintaining information in mind or working memory. It should be noted that the ventrolateral PFC is not just the selection but a controlled selection. If I said "give me a word beginning with F, but no proper names" you might be tempted to immediately say "Frank", "phonetic", the ventrolateral PFC is seen to stop such interfering activity. A further role for this dorsolateral area is the manipulation of information in mind and with the organisation of information according to their semantic relationships. The direct connections with the memory areas within the medial temporal lobe of both these areas suggest that they may function independently but it is just as likely that both these lateral PFC areas are involved in combination with the ventral area searching and selecting and the dorsolateral area holding and temporarily maintaining such information.

The lateral prefrontal cortex is the last prefrontal area to develop estimated to be still developing in individuals into the early twenties which may bear testament to the view that as knowledge increases so do the selective requirements. As the library increases so does the filing system. Less understood are the connections between these two areas with the association areas within the parietal and temporal cortex.

The association area and in particular the junction between the parietal, temporal and occipital cortex is an area that includes the more amodal and abstract representations of different sensory analyses; it is intuitively an ideal area for executive selection. Apart from the evidence that executive dysfunction is found following damage to such areas, there is evidence from non-human studies that this area is a focus for parieto-prefrontal connections and has a role in selective executive attention (see Kravitz et al., 2011). In other words the selective and control features that are attributed to the lateral prefrontal cortex may act on this area that represents knowledge and the focus of attention. In this way stored memories are retrieved into consciousness or working memory and the dorsolateral PFC after an attentional and selective procedure has been completed that involves both the ventrolateral PFC in conjunction with the posterior association areas that focus on the the identity of such information.

Later in this chapter there are descriptions of these respective roles under the heading of executive network.

The more we learn about the cingulate the more there is the realisation that it is a functionally heterogeneous structure. The distinction between mid-cingulate (new term) and the new more rostrally-placed anterior cingulate is well defended by Vogt on the grounds of both differences in cytoarchitecture but also their functional roles. The new terminology in this area has made the distinction between the mid-cingulate that is more obviously associated with motor control especially self-initiation motivated movement and pre-motor speech. The more posterior aspect (pregenual) of the anterior cingulate seems to have a role in modulating the cardiac, thirst, hunger and craving as found in an addicted response with a bio-feedback role. As we progess more rostrally within the anterior cingulate there is an area more associated with conscious introspection and this is most obviously associated with emotional and social introspection in the peri genual area (area peri (around) the genu which is the most rostral point of the corpus calossum). This is a complex area that will no doubt be further divided at some point in the future. This a broad and brief answer. A more comprehensive exam question would require more evidence concerning the case studies that have given evidence of these roles. Parts of the book provided by Vogt (2009) are definitely worth reading.

This is an interesting small area of the literature that nevertheless has implications for the important issue of addictive behaviour. At present there is emerging a literature that makes the distinction between delayed and immediate reward-based behaviour. A pathway involving the PFC and the dorsolateral aspect of the PFC tends to be more active when there is a choice towards delayed gratification often for a larger reward and a more ventromedially active pathway that also eventually involves the basal ganglia that is more related to a decison towards immediate outcomes and rewards. This makes some sense in that in the lateral PFC both dorsolateral and ventrolateral have cognitive roles, while the ventromedial pathway which includes such structures as the orbitofrontal cortex, the amygdala and more notably the nucleus accumbens is more sensitive to reward and is located around the ventral striatum (lower putamen and caudate nucleus as part of the basal ganglia). So, while speculative, it would seem that the dorsal stream is a cognitively-based decision while the ventral pathway (not present in the vulcan brain) is a more emotionally-based decision.

Have a go at this question yourself. The more you think about it the more you will learn. This is a bit like the supermarket example. This is one of those open-ended questions that would hopefully outline the requirements of finding the book in the library and allow thoughts about the planning required (maintained goal-prospective memory) for returning the book on time. When a book is looked at too late, then the immediate reward of reading the book might outweigh the delayed cost of its return etc. There may be some working memory requirements in terms of gauging when the library was open.

This is a pretty straightforward question, but it is of interest that in the past FTD has been under-diagnosed by general practitioners/physicians and AD over-diagnosed. The emotional appropriateness versus the nature of memory impairment are, of course, a good initial starting point. The difficulty is in terms of the memory test. A common mistake is to ignore the need to test delayed memory after interference. Without such a test the clinician is not testing the integrity of the consolidation system.

Something that the author had not considered in the past, but is starting to emerge, is the influence of brain damage or atrophy on the remaining healthy brain, increased connections and cortical thickness in the remaining healthy brain. This may be exhibited in changes of behaviour that reveal compensatory increase in skills served by healthy tissue. A good answer would supply examples of this rather speculative section.

Weblinks

https://www.youtube.com/watch?v=okQac80SiZc
This is a broad description of the types of problems that are typically referred to clinically in the context of executive dysfunction.
http://www.nejm.org/doi/full/10.1056/NEJMicm031024
The Tale of Phineas Gage, digitally remastered.
http://www.youtube.com/watch?v=TtmLVP0HvDgnot
This video clip shows ravens solving problems. This, with the evidence that crows drop nuts on the road in front of cars to crack the shells, indicates that problem solving and executive functioning are present in other species. Jane Goodall describes chimpanzees using straws to obtain termites as a food source.
http://www.slandp.com/?p=138
This site gives a brief description of the Six Elements Test.
http://www.icn.ucl.ac.uk/executive_functions/People/Paul.html
This is Paul Burgess' website describing supermarket and other tests.
https://www.youtube.com/watch?v=dlZxAQkwtOM
This is an interview with Tim Shallice and is probably of main interest to neuropsychology historians. However, there are interesting accounts concerning his development of the SAS model with Don Norman. They start with an introduction and go on from there. His contributions with Elizabeth Warrington in the area of memory are acknowledged which brought a new perspective to the distinction between STM and LTM. There is a somewhat wistful reflection on days when at the applied psychology unit in Cambridge they would have discussions about theoretical matters (not necessarily focused on articles) when there was less pressure on producing publications. His 1988 book From Neuropsychology to Mental Structure is still useful on account of his questioning how neuropsychology should be studied and conceived. There is also the voiced concern about a trend for imaging studies being used merely as methods of functional localisation with the absence of theoretical modelling. He has recently published a text on the neuropsychology of schizophrenia. He talks of a possible reason why Luria took up the more politically neutral area of neuropsychology following the death of Vigotsky.
http://www.youtube.com/watch?v=TtmLVP0HvDgnot
This site is referred to in the text and provides examples of Peter Wilshire's amazing artistic gifts.