Previous work suggests that speech sounds incorporating short-duration spectral changes (such as the formation transitions of stop consonants) rely on left hemisphere mechanisms for their adequate processing to a greater degree than do speech sounds incorporating spectral changes of a longer duration (such as vowel sounds). Ten normal subjects were scanned… (More)
The neural representation of the languages of the polyglot speaker has been highly controversial. We used positron emission tomography (PET) to investigate whether production in a second language (L2) involves the same neural substrates as that of a first language (L1) in normal bilingual subjects who learned L2 after the age of 5 years. Comparison of… (More)
Positron emission tomography (PET) was used to investigate cerebral organization in seven subjects who had Mandarin Chinese as their native language (L1), and learned English (L2) later in life. When activation from word repetition was subtracted from verb generation in L1 and L2, CBF increases were observed for both languages in left inferior frontal,… (More)
We report results from a patient in whom we obtained converging evidence from positron emission tomography (PET) and intraoperative stimulation mapping to support a one-way dissociation between the functional areas involved in word repetition and synonym generation. Intraoperative stimulation mapping interfered with synonym generation but did not disturb… (More)
(1) We have used both subjective and evoked potential tests to study cases of multiple sclerosis with no history of retrobulbar neuritis (spinal patients) and compared them with patients with multiple sclerosis who had experienced an attack of retrobulbar neuritis (RBN). We measured the delay of steady-state evoked potentials (EPs) elicited by flicker in… (More)
We describe a method capable of quantitatively measuring the visual acuity of small, eccentrically-located areas of the visual field, even within the macular area. Fixation errors are minimized by presenting stimuli briefly and in random order. The method is more sensitive than Bjerrum screen campimetry in detecting hemianopic and quadrantic losses.