PubMed · 11264100
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
B Bernal, N R Altman. 2001. Auditory functional MR imaging.. https://doi.org/10.2214/ajr.176.4.1761009
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Altered behavioural and physiological responsivity following a short session of foot shocks in the rat has proven to be a stable and clinically relevant model of stress-induced sensitisation. However, a number of key factors influencing effect size or direction have not previously been reported. Rats underwent a single, 15-min session of foot shocks and were exposed to a variety of novel stressful challenges 1 or 2 weeks later. Sensitised behavioural responses (increased immobility) in preshocked rats remained present over 3 days of repeated exposure to noise stress. In mild novel challenges (open field, empty cage), behavioural sensitisation and defecation was most clearly expressed at the beginning of the dark phase (evening). Higher-arousal challenges (prod, noise) caused increased behavioural inhibition in preshocked rats at all three time points (morning, afternoon, evening). Female preshocked rats showed a different pattern of behavioural and defecation sensitisation than preshocked males. The robustness of the model makes it suitable for further investigations into the mechanisms and vulnerability factors involved in the long-term consequences of stress.
To study the effects of linguistic background on auditory processing, magnetoencephalographic responses for pure tones (120 Hz, 1 and 4 kHz), [u] and a complex tone (with three pure tone components corresponding to the three lowest formant frequencies of [u]) were recorded in ten Finnish and ten Swedish speaking Finnish males. Auditory cortical activation, maximal at about 100 ms after stimulus onset, was stronger in the right hemisphere (RH) for all stimuli. At 175-225 ms, Swedish speaking subjects had larger inter-hemispheric differences and different signal morphology in the RH than Finnish speaking subjects, suggesting that linguistic background influences basic auditory processes. Possibly, Swedish speaking subjects had retained a juvenile response component due to their bilingual surrounding after early childhood.
Repetition of audiogenic seizures (AGS) (AGS kindling) results in increases in the duration of convulsive behavior and the emergence of cortical epileptiform EEG activity. These changes involve expansion of the neuronal network subserving these seizures. The amygdala (AMG) is postulated to become involved in this expanded network, but the neurophysiological basis of this process is unknown. The present study examined changes in chronically-recorded extracellular neuronal firing patterns in the lateral nucleus of AMG (LAMG) induced by AGS kindling in behaving genetically epilepsy-prone rats (GEPR-9s). Before AGS kindling, onset-only (36.1%), onset-delayed (50%) and delayed-only (13.9%) patterns of response to acoustic stimuli were observed. Neuronal firing was greatly suppressed following systemically administered uncompetitive NMDA antagonist (ketamine, 30 mg/kg, i.p.) with complete recovery by 4 h. After AGS kindling, LAMG neurons displayed a significantly increased incidence of onset-only patterns (93.3%, at 0.5 Hz), and mean acoustic responsiveness was also significantly increased (516.2% of control). LAMG neurons fired tonically during tonic convulsions and exhibited burst firing during post-tonic clonus. Greater acoustically-induced synchronization of LAMG firing, as indicated by elevated responsiveness and increased concentration of firing near the stimulus onset, may be critical for mediating the behavioral and EEG changes induced by AGS kindling. LAMG neuronal firing increases induced by AGS kindling may initiate these pathophysiological alterations, in part, by enhanced glutamate receptor-mediated excitation. This possibility is supported by the previously observed ability of an NMDA antagonist to reverse AGS kindling when focally microinjected into AMG, and the blockade of LAMG firing by administration of an uncompetitive NMDA antagonist observed in the present study.