Marisol castañeda b - Academia.edu (original) (raw)
Papers by Marisol castañeda b
Journal of the International Neuropsychological Society, 1998
Semantic memory deterioration is a major component of the cognitive decline seen in patients with... more Semantic memory deterioration is a major component of the cognitive decline seen in patients with dementia of the Alzheimer's type (DAT); however, the exact nature of this deficit remains unclear. Some research data support a procedural deficit where there is an inability to access or retrieve the contents of semantic memory, while other data point to a degraded semantic store where the actual content of semantic memory is degraded. Additional information about semantic processing in DAT can be obtained through the use of an event-related potential (ERP) component known as N400. In the present study, ERPs were recorded from 10 young control participants, 10 elderly control participants, and 10 DAT patients in a picture-semantic matching task. Stimuli were presented sequentially as prime-target pairs, with one-half of the targets matching the primes via semantic relationships (e.g., piano-violin) and the other half mismatching the prime (e.g., helmet-violin). The task was to discriminate between semantically related and unrelated pairs of pictures. In the young and elderly control groups, ERPs generated a larger N400 for unrelated than related target pictures, with a maximum amplitude around 380 ms in the young group and around 480 ms in the elderly group. The amplitude of the N400 was significantly reduced in the DAT patients. However, a separate analysis of congruent and incongruent ERPs trials revealed significant differences only with the incongruent trials. The amplitude of incongruent recordings was larger for the elderly control group than for the DAT patients, while the amplitude for congruent recordings was similar in both groups. These findings are consistent with the neuropathological evidence that Alzheimer's disease is a neocortical disconnection syndrome in which there is a loss of structural and functional integrity of long corticocortical tracts. The semantic activation created by the context is not used efficiently in processing stimuli, which affects access to specific concepts and gradually leads to a breakdown in the structure and organization of semantic memory.
Journal of Neurophysiology, 2012
In hippocampal pyramidal neurons, voltage-gated Ca2+ channels open in response to action potentia... more In hippocampal pyramidal neurons, voltage-gated Ca2+ channels open in response to action potentials. This results in elevations in the intracellular concentration of Ca2+ that are maximal in the proximal apical dendrites and decrease rapidly with distance from the soma. The control of these action potential-evoked Ca2+ elevations is critical for the regulation of hippocampal neuronal activity. As part of Ca2+ signaling microdomains, small-conductance Ca2+-activated K+ (SK) channels have been shown to modulate the amplitude and duration of intracellular Ca2+ signals by feedback regulation of synaptically activated Ca2+ sources in small distal dendrites and dendritic spines, thus affecting synaptic plasticity in the hippocampus. In this study, we investigated the effect of the activation of SK channels on Ca2+ transients specifically induced by action potentials in the proximal processes of hippocampal pyramidal neurons. Our results, obtained by using selective SK channel blockers and...
Salud …, 2003
RESUMEN El Deterioro Cognoscitivo Incipiente (DCI) es un estado de transición entre los cambios d... more RESUMEN El Deterioro Cognoscitivo Incipiente (DCI) es un estado de transición entre los cambios del funcionamiento mental en el envejecimiento normal y la demencia. Este estado se caracteriza por una pérdida subjetiva de la memoria que no concuerda ni con la edad ...
Journal of the International Neuropsychological Society, 1998
Semantic memory deterioration is a major component of the cognitive decline seen in patients with... more Semantic memory deterioration is a major component of the cognitive decline seen in patients with dementia of the Alzheimer's type (DAT); however, the exact nature of this deficit remains unclear. Some research data support a procedural deficit where there is an inability to access or retrieve the contents of semantic memory, while other data point to a degraded semantic store where the actual content of semantic memory is degraded. Additional information about semantic processing in DAT can be obtained through the use of an event-related potential (ERP) component known as N400. In the present study, ERPs were recorded from 10 young control participants, 10 elderly control participants, and 10 DAT patients in a picture-semantic matching task. Stimuli were presented sequentially as prime-target pairs, with one-half of the targets matching the primes via semantic relationships (e.g., piano-violin) and the other half mismatching the prime (e.g., helmet-violin). The task was to discriminate between semantically related and unrelated pairs of pictures. In the young and elderly control groups, ERPs generated a larger N400 for unrelated than related target pictures, with a maximum amplitude around 380 ms in the young group and around 480 ms in the elderly group. The amplitude of the N400 was significantly reduced in the DAT patients. However, a separate analysis of congruent and incongruent ERPs trials revealed significant differences only with the incongruent trials. The amplitude of incongruent recordings was larger for the elderly control group than for the DAT patients, while the amplitude for congruent recordings was similar in both groups. These findings are consistent with the neuropathological evidence that Alzheimer's disease is a neocortical disconnection syndrome in which there is a loss of structural and functional integrity of long corticocortical tracts. The semantic activation created by the context is not used efficiently in processing stimuli, which affects access to specific concepts and gradually leads to a breakdown in the structure and organization of semantic memory.
Journal of Neurophysiology, 2012
In hippocampal pyramidal neurons, voltage-gated Ca2+ channels open in response to action potentia... more In hippocampal pyramidal neurons, voltage-gated Ca2+ channels open in response to action potentials. This results in elevations in the intracellular concentration of Ca2+ that are maximal in the proximal apical dendrites and decrease rapidly with distance from the soma. The control of these action potential-evoked Ca2+ elevations is critical for the regulation of hippocampal neuronal activity. As part of Ca2+ signaling microdomains, small-conductance Ca2+-activated K+ (SK) channels have been shown to modulate the amplitude and duration of intracellular Ca2+ signals by feedback regulation of synaptically activated Ca2+ sources in small distal dendrites and dendritic spines, thus affecting synaptic plasticity in the hippocampus. In this study, we investigated the effect of the activation of SK channels on Ca2+ transients specifically induced by action potentials in the proximal processes of hippocampal pyramidal neurons. Our results, obtained by using selective SK channel blockers and...
Salud …, 2003
RESUMEN El Deterioro Cognoscitivo Incipiente (DCI) es un estado de transición entre los cambios d... more RESUMEN El Deterioro Cognoscitivo Incipiente (DCI) es un estado de transición entre los cambios del funcionamiento mental en el envejecimiento normal y la demencia. Este estado se caracteriza por una pérdida subjetiva de la memoria que no concuerda ni con la edad ...