Advanced Neuropsychology
Literature
Art of Reading an Article in the Journal
Steps in reading a scientific manuscript:
1. Read the title, abstract and conclusion
2. Make decision whether or not to read entire article (based on abstract)
3. Read the introduction → check if a hypothesis is mentioned
4. Read Materials and Methods → get acquitted with the procedures and equipment used for data
collection and find out whether they were appropriate
5. Results of the study → find out whether the results were reliable and valid and if the correct statistical
test was employed for analysis
6. Description and interpretation
7. Discussion → meaning of the results and their analyses. Are the authors’ interpretations and opinions
and not necessarily fact
8. Reading the conclusion again
9. Interpreting conclusions
10. Critical thinking and stimulation for further reading → push back against the author’s interpretation to
test the strength of their conclusions
Title: inform reader a great deal about the value of the study
Abstract: brief overview of the article → read the entire article of not?
Introduction: background information why the topic was chosen and statement of hypothesis
Methods: details of how the study was conducted, procedures and used instruments and variables
Results: all the data of the study and figures, tables and/or graphs
Discussion: interpretation of the results and implications of the study in clinical practice
Answer to the hypothesis/research questions
References/bibliography: citation of the sources from where the information was obtained
1
, Advanced Neuropsychology
Literature
Improving the DSM-5 approach to cognitive impairment: Developmental prosopagnosia
reveals the need for tailored diagnoses
Diagnosing neurocognitive disorders with the DSM-5: patient must score <1 SD below a neurotypical mean on
two cognitive or behavioural tasks → will result in mistaken diagnoses and missed diagnoses
Reasons why the DSM-5 fails to diagnose developmental prosopagnosia:
1. Issues in cognitive and behavioral testing
o Failure to acknowledge diagnostic tests’ limitations
o Validity limitations can cause missed diagnoses
o Imperfect test-retest reliabilities
2. Requiring impairments on a second task will further exclude objectively atypical cases → if one
cognitive task is perfect for diagnosing, then we should simply use one, rather than redundantly
introducing a second
o When requiring impairment on both tests, power will fall below the lowest of the two
Power: chance to find an effect, when there really is an effect
o Person may score below threshold on one test, but well above on the other test
o Only one of the tests may have perfect, or close to perfect, validity
o DSM-5 does not contain sufficient details that enable clinicians and researchers to make
informed choices about which two diagnostic tasks are the most valid
o The strength of the relationship between the two tests will introduce a unique bias into the
types of patients we can diagnose
Consequences of missed diagnoses:
- Will severely impact the lives of patients with neurocognitive disorders and their families
- Negatively impact science → missed cases will bias results
- Impact neurocognitive models
- Treatments can erroneously appear effective due to statistical artefacts
Validating a symptom-based approach to diagnosing
Should encourage the adoption of a more accurate, data-driven approach for diagnosing and treatment, where
researchers and clinicians recognise the limitations of the DSM-5 method
Symptom-based approach → validating a symptom questionnaire
A symptom-based approach offers a more comprehensive and patient centred perspective on diagnoses,
acknowledging the limitations of cognitive tests
→ Diagnostic criteria must be tailored to the unique characteristics of the patient population
2
, Advanced Neuropsychology
Literature
The unity and diversity of executive functions
Early models – Unity | ‘Central executive’ manages lower-level cognitive processes in the context of working
memory → conscious control over attention (Supervisory Attentional System – frontal lobes)
Unitary model of frontal functioning and executive functions – a localized neural substrate underlies a
single control function
Model ideas – Diversity | Multiple brain regions interact with the frontal lobes in the expression of executive
functions
Definitions of executive functions mostly multidimensional → four components
Understanding the number of executive functions requires understanding of their measurement – relied
largely on the use of single tests
o Don’t all necessarily measure the same unitary construct
Problems in research | Inconsistent because of use of single very different tests → label many task-specific
behaviours as separate EF components
EF tests and skills are highly interrelated → over-divided what may be a unified system
Latent variable research on executive functions
Early research on EF | Exploratory analysis: inconsistent results because EF tests are multidimensional and
“impure” → EF tests tap multiple cognitive skills, not just EF
Miyake and Friedman | Confirmatory factor analysis; 3 correlated EF components: 1) inhibition,
2) updating, and 3) shifting
Improved measurement by separating true EF variance from task-specific noise
Are not completely distinct → moderate to high correlations, suggesting shared underlying executive
abilities
Nested (incomplete bifactor) model: 1 general EF + several domain-specific factors
1. All EF tasks load in a general EF factor
2. + specific factors for updating and shifting
3. While inhibition loads only the general factor
→ EF reflects both a common core ability and domain-specific component
Later research | Number of EF factors vary by age → developmental specialization in the brain
Child/adolescent: unidimensional model
o 1 general EF factor → all EF tasks reflect one shared ability
o Cortical areas are functionally nonspecific
Adults: multidimensional; nested-factor
o 1 general EF + several domain-specific factors → tasks share a core EF ability but also have
unique components tied to their cognitive domain
o Cortical areas become specialized through activation, interactions and experience
Greater systems-level integration, particularly within networks that are specialized in EF
The current study aimed to:
1. Determine the empirical support for measurement models of executive functions proposed by past
researchers
2. Identify the number of purported executive functions supported by confirmatory factor analyses in the
current literature
3. Determine which published measurement model best fits summary data across studies.
3
, Advanced Neuropsychology
Literature
Discussion
Main components of EF: 1) inhibition, 2) updating/working memory, and 3) shifting
Number of constructs varies by age:
1. Preschoolers: 1-2 factors (no clear shifting factor)
2. School-age & adolescents: 3-factor or nested models begin to appear
o Increasing differentiation of EF abilities from preschool into adulthood
o Emergence of a specific shifting factor
3. Adults: Mixed support for 2-, 3-, and nested-factor models.
4. Older adults: Mostly 2- or 3-factor models (more research needed!)
o Possible mild de-differentiation but not a full collapse into one EF factor
→ Increasing multidimensionality of executive functions over the course of development
→ Neurodevelopmental theories of brain specialization
Limitations | the results do not offer support for the de-differentiation of executive functions over the course of
adulthood, because the oldes samples evaluated produced a 3-factor model and much of the adult age san is
unrepresente din published research
Reanalysis
For all models evaluated, the reanalysis showed predominantly low rates of model acceptance and model
selection, which likely resulted from issues of low power and poor construct reliability when evaluating fairly
complex measurement models.
The reanalysis provided modest support for a one to two factor model among child/adolescent samples and a
nested factor model among adult samples, which suggests greater unity among younger samples and a balance of
unity and diversity among adult samples. However, considering low rates of model acceptance and selection
overall, these findings are tentative, and no model was accepted unequivocally.
4
, Advanced Neuropsychology
Literature
A new era of executive function research: The transition from centralized to distributed
executive functioning
Executive functions (EFs): higher cognitive control functions → important for adaptive behaviour
1. Working memory: manipulate and maintain chunks of information in short-term memory
2. Inhibition: control one’s attention, behaviour, thoughts, and/or emotions to override a strong internal
predisposition or external lure, and instead do what’s more appropriate or needed
3. Cognitive flexibility: consider multiple conflicting representations of a single object or event
simultaneously and selectively switch between actions, perspectives, and strategies for appropriate
action in a changing environment
Centralized control in cognition and cognitive neuroscience | hierarchical structure (in the past)
A central executive system governs exerted control by “dampening” irrelevant and prioritizing relevant salient
information or schemes → but who is in charge of controlling central executive?
Miller & Cohen: prefrontal cortex (PFC) biases goal-relevant activity patterns in the brain to control executive
functions → selectively prioritizes the relevant processes
Does not act alone? Damage to PFC may or may not be accompanied by deficits in EFs
Modular brain architecture: central executive is a “macro construct” and consists of discrete subsystems with
anatomically segregated and functionally specialized modules
Distinct EFs must also have distinct anatomical representations
Brain regions: prefrontal cortex (PFC), anterior cingulate cortex (ACC), and basal ganglia (BG)
Comments about modular perspective:
- Subsequent tendencies towards reverse inference and inherent bias in interpretation
- Fails to appreciate the activity of this region in context of the other activities in the brain
→ The putative brain areas underlying EFs show large functional overlap → the areas seem to interact
Brain areas that contribute to EFs act within a network and include other structures that may also be relevant to
explain an EF → there is no single brain region as central executive
EFs are the emerging consequence of communication within a broad network of spatially and functionally
brain areas that integrate different aspects of EFs
Distributed control and executive functions
Top-down | Hierarchical architecture: brain areas/circuits underlying EFs regulate, but do not participate in the
more basic cognitive processes that they control → a centrally operating executive
Distributed control system: EF is the result of the interaction between distributed elements → control and
controlled processes are co-localized within large numbers of elements
Each element can be a controller and an element that is being controlled
Behaviour arises from the interaction of all elements → depends on state of the overall system
Key principles for distributed control system:
1. As all elements can be controlled or be a controller
o Prefrontal regions seem to exhibit both basic and control processing
2. The existence of local rules capable of generating the emergent phenomenon
o Biased competition is a general property of neurons across the brain, not limited to any central
controller
3. Robustness to perturbations
o Decentralized networks are resilient systems which can absorb large external perturbations
without undergoing functional breakdown
→ May explain how EFs can be preserved in the case of a lesion and other dysfunctions
5
Literature
Art of Reading an Article in the Journal
Steps in reading a scientific manuscript:
1. Read the title, abstract and conclusion
2. Make decision whether or not to read entire article (based on abstract)
3. Read the introduction → check if a hypothesis is mentioned
4. Read Materials and Methods → get acquitted with the procedures and equipment used for data
collection and find out whether they were appropriate
5. Results of the study → find out whether the results were reliable and valid and if the correct statistical
test was employed for analysis
6. Description and interpretation
7. Discussion → meaning of the results and their analyses. Are the authors’ interpretations and opinions
and not necessarily fact
8. Reading the conclusion again
9. Interpreting conclusions
10. Critical thinking and stimulation for further reading → push back against the author’s interpretation to
test the strength of their conclusions
Title: inform reader a great deal about the value of the study
Abstract: brief overview of the article → read the entire article of not?
Introduction: background information why the topic was chosen and statement of hypothesis
Methods: details of how the study was conducted, procedures and used instruments and variables
Results: all the data of the study and figures, tables and/or graphs
Discussion: interpretation of the results and implications of the study in clinical practice
Answer to the hypothesis/research questions
References/bibliography: citation of the sources from where the information was obtained
1
, Advanced Neuropsychology
Literature
Improving the DSM-5 approach to cognitive impairment: Developmental prosopagnosia
reveals the need for tailored diagnoses
Diagnosing neurocognitive disorders with the DSM-5: patient must score <1 SD below a neurotypical mean on
two cognitive or behavioural tasks → will result in mistaken diagnoses and missed diagnoses
Reasons why the DSM-5 fails to diagnose developmental prosopagnosia:
1. Issues in cognitive and behavioral testing
o Failure to acknowledge diagnostic tests’ limitations
o Validity limitations can cause missed diagnoses
o Imperfect test-retest reliabilities
2. Requiring impairments on a second task will further exclude objectively atypical cases → if one
cognitive task is perfect for diagnosing, then we should simply use one, rather than redundantly
introducing a second
o When requiring impairment on both tests, power will fall below the lowest of the two
Power: chance to find an effect, when there really is an effect
o Person may score below threshold on one test, but well above on the other test
o Only one of the tests may have perfect, or close to perfect, validity
o DSM-5 does not contain sufficient details that enable clinicians and researchers to make
informed choices about which two diagnostic tasks are the most valid
o The strength of the relationship between the two tests will introduce a unique bias into the
types of patients we can diagnose
Consequences of missed diagnoses:
- Will severely impact the lives of patients with neurocognitive disorders and their families
- Negatively impact science → missed cases will bias results
- Impact neurocognitive models
- Treatments can erroneously appear effective due to statistical artefacts
Validating a symptom-based approach to diagnosing
Should encourage the adoption of a more accurate, data-driven approach for diagnosing and treatment, where
researchers and clinicians recognise the limitations of the DSM-5 method
Symptom-based approach → validating a symptom questionnaire
A symptom-based approach offers a more comprehensive and patient centred perspective on diagnoses,
acknowledging the limitations of cognitive tests
→ Diagnostic criteria must be tailored to the unique characteristics of the patient population
2
, Advanced Neuropsychology
Literature
The unity and diversity of executive functions
Early models – Unity | ‘Central executive’ manages lower-level cognitive processes in the context of working
memory → conscious control over attention (Supervisory Attentional System – frontal lobes)
Unitary model of frontal functioning and executive functions – a localized neural substrate underlies a
single control function
Model ideas – Diversity | Multiple brain regions interact with the frontal lobes in the expression of executive
functions
Definitions of executive functions mostly multidimensional → four components
Understanding the number of executive functions requires understanding of their measurement – relied
largely on the use of single tests
o Don’t all necessarily measure the same unitary construct
Problems in research | Inconsistent because of use of single very different tests → label many task-specific
behaviours as separate EF components
EF tests and skills are highly interrelated → over-divided what may be a unified system
Latent variable research on executive functions
Early research on EF | Exploratory analysis: inconsistent results because EF tests are multidimensional and
“impure” → EF tests tap multiple cognitive skills, not just EF
Miyake and Friedman | Confirmatory factor analysis; 3 correlated EF components: 1) inhibition,
2) updating, and 3) shifting
Improved measurement by separating true EF variance from task-specific noise
Are not completely distinct → moderate to high correlations, suggesting shared underlying executive
abilities
Nested (incomplete bifactor) model: 1 general EF + several domain-specific factors
1. All EF tasks load in a general EF factor
2. + specific factors for updating and shifting
3. While inhibition loads only the general factor
→ EF reflects both a common core ability and domain-specific component
Later research | Number of EF factors vary by age → developmental specialization in the brain
Child/adolescent: unidimensional model
o 1 general EF factor → all EF tasks reflect one shared ability
o Cortical areas are functionally nonspecific
Adults: multidimensional; nested-factor
o 1 general EF + several domain-specific factors → tasks share a core EF ability but also have
unique components tied to their cognitive domain
o Cortical areas become specialized through activation, interactions and experience
Greater systems-level integration, particularly within networks that are specialized in EF
The current study aimed to:
1. Determine the empirical support for measurement models of executive functions proposed by past
researchers
2. Identify the number of purported executive functions supported by confirmatory factor analyses in the
current literature
3. Determine which published measurement model best fits summary data across studies.
3
, Advanced Neuropsychology
Literature
Discussion
Main components of EF: 1) inhibition, 2) updating/working memory, and 3) shifting
Number of constructs varies by age:
1. Preschoolers: 1-2 factors (no clear shifting factor)
2. School-age & adolescents: 3-factor or nested models begin to appear
o Increasing differentiation of EF abilities from preschool into adulthood
o Emergence of a specific shifting factor
3. Adults: Mixed support for 2-, 3-, and nested-factor models.
4. Older adults: Mostly 2- or 3-factor models (more research needed!)
o Possible mild de-differentiation but not a full collapse into one EF factor
→ Increasing multidimensionality of executive functions over the course of development
→ Neurodevelopmental theories of brain specialization
Limitations | the results do not offer support for the de-differentiation of executive functions over the course of
adulthood, because the oldes samples evaluated produced a 3-factor model and much of the adult age san is
unrepresente din published research
Reanalysis
For all models evaluated, the reanalysis showed predominantly low rates of model acceptance and model
selection, which likely resulted from issues of low power and poor construct reliability when evaluating fairly
complex measurement models.
The reanalysis provided modest support for a one to two factor model among child/adolescent samples and a
nested factor model among adult samples, which suggests greater unity among younger samples and a balance of
unity and diversity among adult samples. However, considering low rates of model acceptance and selection
overall, these findings are tentative, and no model was accepted unequivocally.
4
, Advanced Neuropsychology
Literature
A new era of executive function research: The transition from centralized to distributed
executive functioning
Executive functions (EFs): higher cognitive control functions → important for adaptive behaviour
1. Working memory: manipulate and maintain chunks of information in short-term memory
2. Inhibition: control one’s attention, behaviour, thoughts, and/or emotions to override a strong internal
predisposition or external lure, and instead do what’s more appropriate or needed
3. Cognitive flexibility: consider multiple conflicting representations of a single object or event
simultaneously and selectively switch between actions, perspectives, and strategies for appropriate
action in a changing environment
Centralized control in cognition and cognitive neuroscience | hierarchical structure (in the past)
A central executive system governs exerted control by “dampening” irrelevant and prioritizing relevant salient
information or schemes → but who is in charge of controlling central executive?
Miller & Cohen: prefrontal cortex (PFC) biases goal-relevant activity patterns in the brain to control executive
functions → selectively prioritizes the relevant processes
Does not act alone? Damage to PFC may or may not be accompanied by deficits in EFs
Modular brain architecture: central executive is a “macro construct” and consists of discrete subsystems with
anatomically segregated and functionally specialized modules
Distinct EFs must also have distinct anatomical representations
Brain regions: prefrontal cortex (PFC), anterior cingulate cortex (ACC), and basal ganglia (BG)
Comments about modular perspective:
- Subsequent tendencies towards reverse inference and inherent bias in interpretation
- Fails to appreciate the activity of this region in context of the other activities in the brain
→ The putative brain areas underlying EFs show large functional overlap → the areas seem to interact
Brain areas that contribute to EFs act within a network and include other structures that may also be relevant to
explain an EF → there is no single brain region as central executive
EFs are the emerging consequence of communication within a broad network of spatially and functionally
brain areas that integrate different aspects of EFs
Distributed control and executive functions
Top-down | Hierarchical architecture: brain areas/circuits underlying EFs regulate, but do not participate in the
more basic cognitive processes that they control → a centrally operating executive
Distributed control system: EF is the result of the interaction between distributed elements → control and
controlled processes are co-localized within large numbers of elements
Each element can be a controller and an element that is being controlled
Behaviour arises from the interaction of all elements → depends on state of the overall system
Key principles for distributed control system:
1. As all elements can be controlled or be a controller
o Prefrontal regions seem to exhibit both basic and control processing
2. The existence of local rules capable of generating the emergent phenomenon
o Biased competition is a general property of neurons across the brain, not limited to any central
controller
3. Robustness to perturbations
o Decentralized networks are resilient systems which can absorb large external perturbations
without undergoing functional breakdown
→ May explain how EFs can be preserved in the case of a lesion and other dysfunctions
5
