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Electrical recordings from the surface of the skull have a wide range of rhythmic components. A major task of analysis of this EEG is to determine their source and functional significance. The hippocampal "theta rhythm" has been extensively studied in rats and its rhythmicity has recently been shown to be functionally significant, per se. Here, we use(More)
Long-term potentiation (LTP) is a candidate synaptic mechanism underlying learning and memory that has been studied extensively at the cellular and molecular level in laboratory animals. To date, LTP has only been directly demonstrated in humans in isolated cortical tissue obtained from patients undergoing surgery, where it displays properties identical to(More)
  • I J Kirk
  • 1998
In this paper it is argued that theta-range hippocampal EEG activity, and in particular the specific frequency at which it occurs, is critical to hippocampal function. Results of the reviewed studies suggest that in particular circumstances (in the urethane anaesthetized animal and possibly during particular behavioral states), the frequency of hippocampal(More)
We have previously shown that in urethane-anesthetized rats the frequency of rhythmical slow activity in the hippocampus ("theta") is controlled by the medial supramammillary nucleus (SuM). In particular, injections of procaine into SuM in urethane-anesthetized animals reduce the frequency of theta. However, it has been reported that, in freely moving(More)
Congenital amusia is a disorder in the perception and production of musical pitch. It has been suggested that early exposure to a tonal language may compensate for the pitch disorder (Peretz, 2008). If so, it is reasonable to expect that there would be different characterizations of pitch perception in music and speech in congenital amusics who speak a(More)
BACKGROUND Functional imaging studies of people with focal hand dystonia (FHD) have indicated abnormal activity in sensorimotor brain regions. Few studies however, have examined FHD during movements that do not provoke symptoms of the disorder. It is possible, therefore, that any differences between FHD and controls are confounded by activity due to the(More)
The degree to which cognitive resources are shared in the processing of musical pitch and lexical tones remains uncertain. Testing Mandarin amusics on their categorical perception of Mandarin lexical tones may provide insight into this issue. In the present study, a group of 15 amusic Mandarin speakers identified and discriminated Mandarin tones presented(More)
It is well established that the occurrence of theta rhythm in the hippocampus is important in a variety of mnemonic tasks. However, in this review it will be argued that theta-rhythmic activity occurs across distributed networks within the diencephalon and neocortex as well as the hippocampus, and functions to temporally coordinate activity in distributed(More)
OBJECTIVES The aim of this study was to examine the N300 and N400 effect to pictures that were semantically incongruous to a prior object name. Based upon theories of object identification, the semantic incongruity was manipulated to occur early or late in the object processing stream. METHODS High-density visual event-related potentials were measured in(More)
Hippocampal rhythmical slow activity (RSA, theta) was elicited in urethanized rats by high-frequency stimulation in the reticular formation. The effects of procaine infusion (0.5 microliters, 20% wt/vol) at various loci in the ascending system from pontine reticular formation to the medial septum/diagonal band area were investigated. It was found that(More)