The role of executive functions in long-term memory: case report.

The role of executive functions in long-term memory has been studied. We describe a single-case study, consisting of a 45-year-old male patient, hospitalized for right frontal stroke. After the stroke, the patient had memory alterations in everyday activities. However, performance in short-term memory tests was not significantly altered. Long-term memory assessments included pre- and post-stroke episodic, semantic, and procedural memories. Specific skills involved in the acquisition of new learning (auditory-verbal and visual reproduction) were also evaluated, as well as executive functions. The results evidence that short-term memory was not affected. Regarding long-term memory, significant differences were observed between pre- and post-stroke knowledge, the former being better preserved, which reveals anterograde amnesia. Pre-stroke long-term memory was also affected, but only with respect to episodic knowledge, with semantic and procedural memories preserved (episodic retrograde amnesia). Executive functions were altered as well, which could have been a factor affecting the acquisition and consolidation of new learning, despite the fact that short-term memory was not significantly altered. Therefore, executive functions might be a determinant factor in the acquisition of new learning, regardless of short-term memory processes, at least partially. According to the results of the present study, alterations in these functions might lead to anterograde amnesia. This entails the need to evaluate executive functions as an intrinsic part of memory evaluation.

The number processing and calculation system: evidence from cognitive neuropsychology.

INTRODUCTION: Cognitive neuropsychology focuses on the concepts of dissociation and double dissociation. The performance of number processing and calculation tasks by patients with acquired brain injury can be used to characterise the way in which the healthy cognitive system manipulates number symbols and quantities. The objective of this study is to determine the components of the numerical processing and calculation system. METHODS: Participants consisted of 6 patients with acquired brain injuries in different cerebral localisations. We used Batería de evaluación del procesamiento numérico y el cálculo, a battery assessing number processing and calculation. Data was analysed using the difference in proportions test. RESULTS: Quantitative numerical knowledge is independent from number transcoding, qualitative numerical knowledge, and calculation. Recodification is independent from qualitative numerical knowledge and calculation. Quantitative numerical knowledge and calculation are also independent functions. CONCLUSIONS: The number processing and calculation system comprises at least 4 components that operate independently: quantitative numerical knowledge, number transcoding, qualitative numerical knowledge, and calculation. Therefore, each one may be damaged selectively without affecting the functioning of another. According to the main models of number processing and calculation, each component has different characteristics and cerebral localisations.

[The functional independence of lexical numeric knowledge and the representation of magnitude: evidence from one case]. / Independencia funcional del conocimiento numérico léxico y la representación de la magnitud: evidencia de un caso.

INTRODUCTION: The ultimate purpose of cognitive neuropsychology is to find out how normal cognitive processes work. To this end, it studies subjects who have suffered brain damage but who, until their accident, were competent in the skills that are later to become the object of study. It is therefore necessary to study patients who have difficulty in processing numbers and in calculating in order to further our knowledge of these processes in the normal population. AIMS: Our aim was to analyse the relationships between the different cognitive processes involved in numeric knowledge. CASE REPORT: We studied the case of a female patient who suffered an ischemic infarct in the perisylvian region, on both a superficial and deep level. She presented predominantly expressive mixed aphasia and predominantly brachial hemiparesis. Numeric processing and calculation were evaluated. The patient still had her lexical numeric knowledge but her quantitative numeric knowledge was impaired. These alterations in the quantitative numeric knowledge are evidenced by the difficulties the patient had in numeric comprehension tasks, as well as the severe impairments displayed in calculation. CONCLUSIONS: These findings allow us to conclude that quantitative numeric knowledge is functionally independent of lexical or non-quantitative numeric knowledge. From this functional autonomy, a possible structural independence can be inferred.

[Numerical and calculation processing: evidence for a case from cognitive neuropsychology]. / Procesamiento numérico y cálculo: evidencia de un caso desde la neuropsicología cognitiva.

INTRODUCTION: This paper, which deals with cognitive Neuropsychology, attempts to contribute to the understanding of normal cognitive processing by examining and analysing the deficits acquired by individuals who have suffered brain damage. AIMS: Our aim was to analyse the different cognitive processes involved in numerical processing (NP) and in calculation, together with the relations between them. PATIENTS AND METHODS: A quadriplegic patient with sequelae that include motor aphasia and deep dysgraphia as the residual pathologies of a traumatic brain injury, with a history of over four years; language comprehension is preserved (both oral and written) and there is no verbal expression whatsoever. Expression is achieved functionally by means of a specially adapted laser pointer. Assessment of NP and calculation was performed. RESULTS: Alterations were observed in the calculation system, one in the recognition of arithmetical signs and the other in the execution of arithmetical operations. CONCLUSIONS: 1. Calculation skills are independent of those required to perform numerical recoding and of lexical or encyclopaedic numerical knowledge. 2. Recognition of arithmetical signs is independent of, and therefore dissociated from, data retrieval and the execution of calculation procedures. 3. Data retrieval processes and those required for the execution of calculations are independent. Therefore, the calculation system consists of different elements that are independent from one another.