Search results for "Cortex"
showing 10 items of 1827 documents
Hippocampus responds to auditory change in rabbits
2010
Any change or novelty in the auditory environment is potentially important for survival. The cortex has been implicated in the detection of auditory change whereas the hippocampus has been associated with the detection of auditory novelty. Local field potentials (LFPs) were recorded from the CA1 area of the hippocampus in waking rabbits. In the oddball condition, a rare tone of one frequency (deviant) randomly replaced a repeated tone of another frequency (standard). In the equal-probability condition, the standard was replaced by a set of tones of nine different frequencies in order to remove the repetitive auditory background of the deviant (now labelled as control-deviant) while preservi…
Characterization of rodent pineal astrocytes by immunofluorescence microscopy using a monoclonal antibody (J1-31).
1987
In previous studies pineal astrocytes have been characterized immunohistochemically mainly by use of antisera to glial fibrillary acidic protein. Because of the recent demonstration of this protein in non-astrocytic cells the question of its specificity as an astrocytic marker has been raised. A possible alternative tool for characterizing pineal astrocytes is the J1-31 monoclonal antibody, which is directed against a 30 000 dalton astrocytic protein clearly distinguishable from glial fibrillary acidic protein. Immunofluorescence microscopy of this antibody in the pineal gland of rat and guinea-pig revealed a staining pattern similar to that obtained by glial acidic fibrillary protein antis…
Neuropeptide Y (NPY)-like immunoreactivity in peripheral and central nerve fibres of the golden hamster (Mesocricetus auratus) with special respect t…
1986
Inforimation on the ambient lighting conditions is conveyed from the retina to the pineal organ by a neuronal pathway involving the suprachiasmatic nucleus (SCN) which acts as a circadian pacemaker. In the hamster, circadian rhythms have been shown to be influenced by injection of neuropeptide Y (NPY) into the SCN. Since NPY-immunoreactive nerve fibres are present in the rat and guinea-pig pineal glands it appeared of interest to investigate the hamster pineal as part of the circadian rhythm generating/regulating system. For comparison kidney, small intestine and cerebral cortex were studied. Like in the other rodent species so far investigated only a few of the abundant sympathetic nerve f…
24-hour-variation of pineal gland volume, pinealocyte nuclear volume and mitotic activity in male Sprague-Dawley rats
1983
In two experiments carried out on two alternate days, the 24-h-rhythmicity of pineal gland volume, pinealocyte nuclear size in cortex and medulla and mitotic activity were studied in male Sprague-Dawley rats, to assess to what extent morphological parameters reflect the pronounced day/night differences in pineal melatonin formation. Pineal volume exhibited statistically significant changes in the second experiment only, with a distinct trough at 6 p.m. Karyometry revealed highly variable patterns. In the first experiment, pinealocyte nuclear changes lacked parallelism in cortex and medulla. The cortex exhibited a bimodal curve with peaks at noon of the first day and at 6 a.m. of the second …
Neuropeptide Y: distribution of immunoreactivity and quantitative analysis in diencephalic structures and cerebral cortex of dwarf hamsters under dif…
1995
The distribution of neuropeptide Y-like immunoreactivity (NPY-LI) was investigated by immunohistochemistry and radioimmunoassay (RIA) in the brain of the Djungarian hamster (Phodopus sungorus) held under either long or short photoperiods. In the diencephalic and telencephalic structures studied, distinct patterns of NPY-LI were basically consistent in male and female animals of both groups. NPY levels detected by RIA from tissue samples taken at six time points throughout the 24-hour cycle were in the range of 15-60 pmol/mg protein in the diencephalon or below 5 pmol/mg protein in cerebral cortex. In the diencephalon, immunoreactive structures were seen in the preoptic, peri- and paraventri…
Sex differences in GABAA receptor binding in rat brain measured by an improved in vitro binding assay.
1990
The distribution of GABAA receptor sites was studied in female and male rat brain by an improved in vitro binding assay using 3H-muscimol and carefully washed membrane fractions. The binding studies revealed a single class of binding sites exhibiting the properties of GABAA receptors. The specific binding of 3H-muscimol was measured in four brain areas: the preoptic brain area, mediobasal hypothalamus, corticomedial amygdala and cerebral cortex. The equilibrium dissociation constants (KD) ranged from 11.2 to 23.3 nM in diestrous females and from 13.1 to 50.4 nM in males, the maximal number of binding sites (Bmax) from 3290 to 10240 fmol/mg protein in females and from 5495 to 17449 fmol/mg p…
In vivo definition of parieto-motor connections involved in planning of grasping movements
2010
We combined bifocal transcranial magnetic stimulation (TMS) and diffusion tensor imaging (DTI) tractography to investigate in humans the contribution of connections originating from different parietal areas in planning of different reaching to grasp movements. TMS experiments revealed that in the left hemisphere functional connectivity between the primary motor cortex (M1) and a portion of the angular gyrus (AG) close to the caudal intraparietal sulcus was activated during early preparation of reaching and grasping movements only when the movement was made with a whole hand grasp (WHG) towards objects in contralateral space. In contrast, a different pathway, linking M1 with a part of the su…
Effects of electrical stimulation in vestibular cortex areas in humans.
2010
The case of a patient with focal epilepsy is reported who underwent presurgical evaluation by stereotactic intracranial electroencephalographic (EEG) recording. A subdural semi-grid electrode, consisting of three multi-channel strip electrodes, was implanted over the temporal lobe and temporo-occipital region; one multi-channel depth electrode was applied towards the posterior insular cortex. During electrical stimulation and EEG monitoring eye movements were recorded by 3-D video-oculography. Stimulation of the medial temporal gyrus induced blurring of vision and horizontal nystagmus. Stimulation of the superior temporal gyrus with low intensities also induced blurring of vision and a simi…
Coupling between simultaneously recorded BOLD response and neuronal activity in the rat somatosensory cortex
2007
Abstract Understanding the link between the hemodynamic response and the underlying neuronal activity is important for interpreting functional magnetic resonance (fMRI) signals in human and animal studies. Simultaneous electrophysiological and functional imaging measurements provide a knowledge of information processing and communication in the brain with high spatial and temporal resolution. In this study, a range of neural and blood oxygenation level-dependent (BOLD) responses were elicited in the rat somatosensory cortex by changing the type of anesthesia (urethane or alpha-chloralose) and the electrical forepaw stimulus frequency (1–15 Hz). Duration of the stimulus was 30 s. Electrical …
Modality-independent recruitment of inferior frontal cortex during speech processing in human infants
2018
Despite increasing interest in the development of audiovisual speech perception in infancy, the underlying mechanisms and neural processes are still only poorly understood. In addition to regions in temporal cortex associated with speech processing and multimodal integration, such as superior temporal sulcus, left inferior frontal cortex (IFC) has been suggested to be critically involved in mapping information from different modalities during speech perception. To further illuminate the role of IFC during infant language learning and speech perception, the current study examined the processing of auditory, visual and audiovisual speech in 6-month-old infants using functional near-infrared s…