ABSTRACT
Stimulus-specific adaptation (SSA), defined as a decrease in responses to a common stimulus that only partially generalizes to other rare stimuli, is a widespread phenomenon in the brain that is believed to be related to novelty detection. Although cross-modal sensory processing is also a widespread phenomenon, the interaction between the two phenomena is not well understood. In this study, the thalamic reticular nucleus (TRN), which is regarded as a hub of the attentional system that contains multi-modal neurons, was investigated. The results showed that SSA existed in an interactive oddball stimulation, which mimics stimulation changes from one modality to another. In the bimodal integration, SSA to bimodal stimulation was stronger than to visual stimulation alone but similar to auditory stimulation alone, which indicated a limited integrative effect. Collectively, the present results provide evidence for independent cross-modal processing in bimodal TRN neurons.
Subject(s)
Animals , Rats , Acoustic Stimulation , Auditory Perception/physiology , Geniculate Bodies , Rats, Wistar , Thalamic Nuclei/physiologyABSTRACT
La estimulación bilateral de lo núcleos anterodorsales talámicos (NADT) produjo una significativa disminución en la concentración de corticosterona plasmática y adrenal. Las ratas con lesión bilateral de NADT mostraran una mayor respuesta de corticosterona plasmática al estrés agudo que las ratas control (falsa lesión). Las ratas controles estresadas presentan valores de cortiscosterona adrenal más altos que las no estresadas mientras que en las lesionadas estresadas los valores fueron significativamente más bajos que en las lesionadas no estresadas. Las concentraciones de catecolaminas adrenalaes, Noradrenalina (NA) y Adrenalina (A), en las ratas control no se modifcan por el estrés. En las ratas lesionadas estresadas las glándulas adrenales contienen cuatro veces más de NA y dos veces más de A que las glándulas adrenales de las lesionadas no estresadas
Subject(s)
Animals , Female , Rats , Adrenal Glands/physiology , Thalamic Nuclei/physiology , Corticosterone/metabolism , Electric Stimulation , Epinephrine/metabolism , Norepinephrine/metabolism , Rats, Wistar , Stress, Physiological/metabolism , Stress, Physiological/physiopathologyABSTRACT
Los estudios electrofisiológicos sobre neuronas del núcleo supraquiasmático en cortes cerebrales in vitro de la rata, revelan patrones característicos de descarga que han sido previamente clasificados como regulares, irregulares y en estallidos. Se ha encontrado una nueva clase de descarga neuronal, al analizar la distribución entre los intervalos inter-espiga. Basándose en estos resultados se sugiere un nuevo esquema de clasificación. Se propone un modelo que explique la presencia de todos los patrones experimentales. El modelo no sólo infiere la presencia de oscilaciones regulares, sino también sugiere consecuencias interesantes en relación a los componentes del sistema circadiano y su conducta estadística.
Subject(s)
Animals , Male , Adult , Rats , Heart Rate/physiology , In Vitro Techniques , Neurons/physiology , Thalamic Nuclei/physiology , Rats, Inbred Strains/physiology , RatsABSTRACT
The electrical activity of the posterior thalamic nuclear complex was studied in rats and related to the simultaneous hippocampal electro-oscillogram. Electrocorticographic tracings and spectral analysis showed that during attentive wakefulness the electro-oscillogram peaked at 8 Hz and in desynchronized sleep it oscillated at regular frequencies between 8 and 9 Hz. In quiet wakefulness, frequency was lower (around 5 Hz) and during synchronized sleep rhytmicity disppeared. The electrophysiological patterns during wakefulness and desynchronized sleep are proposed to be linked to the retrieeval and combination of information for the generation of attention and dream content
Subject(s)
Rats , Animals , Male , Female , Hippocampus/physiology , Thalamic Nuclei/physiology , Sleep/physiology , Wakefulness/physiology , Electrophysiology , Oscillometry , Rats, Wistar , Spectrum AnalysisABSTRACT
The behavioural and electroencephalographic responses resulting from stimulation of a specific area in the nucleus medialis dorsalis (nMD) of unanaesthetized juvenile Rhesus monkeys is described. A behavioural arrest reaction, lack of awareness and motor inhibition with concomitant 2 1/2 to 3Hz spike and wave EEG afterdischarge patterns were obtained by stimulation of the nMD in monkeys with bilaterally symmetrical aluminium hydroxide Al (OH)3 lesions in anterior premotor cortical areas.
Subject(s)
Aluminum Hydroxide/toxicity , Animals , Autonomic Nervous System/physiology , Electric Stimulation , Electrocardiography , Electroencephalography , Electrooculography , Macaca mulatta , Male , Motor Activity/drug effects , Thalamic Nuclei/physiology , Thalamus/physiologyABSTRACT
A bilaterally synchronous 3/sec spike and wave pattern in the EEG can be obtained during stimulation of the nucleus medialis dorsalis (nMD) and nucleus paracentralis (nPC) of the thalamus, in lightly anaesthetized juvenile monkeys. The spike and wave EEG patterns have a frequency of 2 1/2 to 3Hz and occur during low frequency stimulation, without continuing into the post-stimulatory phase. Stimulation of the mesencephalic reticular formation (MRF) at higher voltages inhibits the thalamic-induced spike and wave response. This finding has heuristic significance, as activating stimuli arrest the wave and spike EEG pattern of human absence (petit mal epilepsy) seizures. The study also demonstrates the morphological similarity of the 3/sec spike and wave thalamic induced response in experimental and clinical absence states as well as similarities in their alterations with different levels of activation.