Methodological issues and controversies in research on cognitive disorders

Abstract

Research on cognitive disorders is challenging due to the complexity of functions studied and to the numerous variables involved. First, the concept of cognition as a mediated (semiotic) and systemic activity is reviewed. According to this concept, the result of a local lesion is not an isolated symptom but a syndrome, and the best neuropsychological approach is an analysis based on appropriate tests to disclose double dissociations and thereby provide clues to brain-behavior relationships. This approach takes into account the influence of task-relevant variables (confounders) related to the patient (e.g., age, education), to the lesion (size, etiology), and to the tests and testing conditions (ecological validity, examiner’s experience), which need to be controlled and analyzed in multivariate statistical analyses, as illustrated in research on medial temporal lobe epilepsy. Other controversial issues such as single and double dissociations, single-case versus group studies, and the lesion method are also examined.

Recall and Self-Relevance of Emotional Words Predict Subjective Self-Evaluation of Cognition in Patients with MTLE with or without Depressive Symptoms

“…Because the behavioral task revealed memory deficit in our MTLE patients, our study may contribute useful evidence from a methodological point of view. Using behavioral tasks to probe memory or other functions may have ecological validity [ 23 , 47 ], resulting in an increased likelihood of detecting functional deficits. On this view, the lack of ecological validity of some standardized tests [ 23 , 47 ] may be a reason for non-confirmed subjective self-evaluation of cognition in epilepsy patients’ evaluations [ 1 , 4 , 8 , 9 ].…”

“…Using behavioral tasks to probe memory or other functions may have ecological validity [ 23 , 47 ], resulting in an increased likelihood of detecting functional deficits. On this view, the lack of ecological validity of some standardized tests [ 23 , 47 ] may be a reason for non-confirmed subjective self-evaluation of cognition in epilepsy patients’ evaluations [ 1 , 4 , 8 , 9 ]. Furthermore, the MTLE patients’ subjective self-evaluation of cognition was predicted by the total number of recalled words and the number of self-rated negative words.…”

“…In terms of clinical variables related to depression, higher levels of depressive symptoms are suggested to be related to a later age of seizure onset [ 17 ], longer epilepsy duration [ 18 , 19 ], higher seizure frequency [ 20 ] and antiseizure medication polytherapy [ 21 ]. In addition, poorer subjective self-evaluation of cognition has been associated with longer epilepsy duration and higher seizure frequency [ 22 , 23 ]. Therefore, we examined whether the clinical variables previously shown to be relevant to depression could help predict the subjective self-evaluation of cognition in patients with MTLE.…”

“…One factor which may prevent the objective confirmation of subjective self-evaluated cognitive difficulties could be related to the manner of assessing MTLE patients’ cognitive abilities, which is often limited to standard test-based evaluations [ 1 , 2 , 3 , 4 , 8 ]. Indeed, the approach based exclusively on neuropsychological tests has been criticized by some authors [ 23 , 47 ] for its lack of ecological validity, meaning that such tests may not measure behaviors that are relevant to real-life settings. Therefore, behavioral tasks could potentially serve as an additional method for assessing cognitive abilities in patients with MTLE.…”

Neural substrates involved in the cognitive information processing in teleost fish

“…Last but not least, one always has to consider further surgery effects, such as causing motivational, sensory or motor impairments that keep animals from performing at the same level as prior to surgery. For example, damaging the target area could cause a hyperactivation or hyperinactivation of other brain regions that, under normal conditions, are activated or inhibited by the damaged region (Fuster 1989 ; Damasceno 2010 ). Some of these shortcomings can be overcome using sham-operated and control animals, as well as lesioning a larger number of individuals (also to overcome intra-specific variation).…”