Showing papers by "Gregory McCarthy published in 1997"
TL;DR: It is suggested that a decrease in left hippocampal volume is associated with abuse-related PTSD.
1,194 citations
TL;DR: It is demonstrated that both faces and flowers activate large and partially overlapping regions of inferior extrastriate cortex, and a smaller region, located primarily in the right lateral fusiform gyrus, is activated specifically by faces.
Abstract: The perception of faces is sometimes regarded as a specialized task involving discrete brain regions. In an attempt to identi$ face-specific cortex, we used functional magnetic resonance imaging (fMRI) to measure activation evoked by faces presented in a continuously changing montage of common objects or in a similar montage of nonobjects. Bilateral regions of the posterior fusiform gyrus were activated by faces viewed among nonobjects, but when viewed among objects, faces activated only a focal right fusiform region. To determine whether this focal activation would occur for another category of familiar stimuli, subjects viewed flowers presented among nonobjects and objects. While flowers among nonobjects evoked bilateral fusiform activation, flowers among objects evoked no activation. These results demonstrate that both faces and flowers activate large and partially overlapping regions of inferior extrastriate cortex. A smaller region, located primarily in the right lateral fusiform gyrus, is activated specifically by faces.
1,127 citations
TL;DR: McCarthy et al. as discussed by the authors found that frequent events transiently activate human prefrontal and parietal cortex as measured by functional MRI, and that the prefrontal cortex is more sensitive to frequent events than the other parts of the brain.
Abstract: McCarthy, Gregory, Marie Luby, John Gore, and Patricia Goldman-Rakic. Infrequent events transiently activate human prefrontal and parietal cortex as measured by functional MRI. J. Neurophysiol. 77:...
462 citations
TL;DR: Systematic fMRI studies are possible in patients with vascular malformations in brain regions adjacent to primary somatosensory, motor, and visual cortex and changes in fMRI findings after intervention reflect the consequences of therapy and parallel clinical recovery.
Abstract: Background and Purpose It is not known how cerebral vascular malformations affect the function of the surrounding brain. Functional magnetic resonance imaging (fMRI) can provide information about normal functional neuroanatomy and its alteration by vascular lesions and therapeutic intervention. Methods We performed fMRI studies in 24 patients harboring vascular malformations adjacent to primary somatosensory, motor, and visual cortex. The fMRI studies consisted of the acquisition of an image time series coupled with functional activation of motor, sensory, or visual cortex in both hemispheres. Activated voxels were identified using frequency domain analyses, and their number and anatomic location were compared between the affected and unaffected hemispheres. Results Every patient capable of performing the desired task showed functional activation. Eight patients without neurological deficits showed a symmetrical pattern of activation between the hemispheres. Each had a vascular malformation located one or...
100 citations
TL;DR: The localization of neural processes contributing to face perception was studied in two patients using event‐related field potentials (ERPs) recorded from subdural strips and functional magnetic resonance imaging (fMRI).
Abstract: The localization of neural processes contributing to face perception was studied in two patients using event-related field potentials (ERPs) recorded from subdural strips and functional magnetic resonance imaging (fMRI). Despite the differences in the physiological bases of the two techniques, and in the tasks used to elicit activation, good correspondence was obtained in the anatomical patterns of activation. Face-specific ERPs (N200s) and fMRI activation by faces occurred at the same locations in the right ventral extrastriate region of both patients, and in a similar region of the left hemisphere of one patient. Some discrepancies were noted in the pattern of activation which may reflect the adequacy of the tasks in identifying face-specific as opposed to face-sensitive processing, and in the differential sensitivity of the methods to the temporal course of face processing.
85 citations
TL;DR: The presence of HcA is not an independent predictor of the site of epileptogenesis, as detected by volumetric MRI in patients with refractory epilepsy.
Abstract: Objective To establish if MRI evidence of hippocampal atrophy (HcA) is an independent surrogate of EEG criteria for the diagnosis of medial temporal lobe (MTL) epilepsy (MTLE). Background MRI evidence of HcA has been shown to correlate with mesial temporal sclerosis (MTS), intracranial evidence of MTL seizure onset, and outcome after temporal lobectomy. The reported rate of discordance between scalp ictal EEG recordings and MRI evidence of unilateral HcA ranges from rare to moderate. We examined the surface and depth ictal EEG findings of patients with HcA, as detected by volumetric MRI, to clarify their significance in detecting areas of epileptogenicity in this group of patients. Methods From a group of patients with refractory epilepsy, we identified 119 patients with HcA (97 with unilateral and 13 with bilateral HcA, 9 with HcA and mass lesion). MRI volumetric studies were used to obtain Hc ratios. Absolute volumes were used to detect bilateral atrophy. Surface and depth EEG recordings were analyzed for localization of ictal abnormalities, and their distribution was compared for concordance with the location of HcA. Surgical outcome was reviewed. Results Of the 110 patients with isolated HcA, 63 had surgery; 82% of ictal depth EEG onsets were concordant with the atrophic Hc, and 72% ictal surface EEG onsets were concordant. Four patients with concordant EEG and HcA failed to achieve seizure control with resection of the atrophic Hc. Furthermore, 3 patients with discordant EEG and HcA had resection of the non-atrophic Hc with excellent results. Among the 47 non-operated patients, 54% had discordant or unlocalized ictal depth EEG results and 52% had discordant ictal surface EEG. Four of the 9 lesional patients with HcA had excellent outcome after lesionectomy without hippocampectomy. Conclusion The presence of HcA is not an independent predictor of the site of epileptogenesis.
63 citations
TL;DR: It is concluded that intensivelytreated IDDM patients are resistant to changes in cortical evoked potentials induced by mild hypoglycemia, which may explain why intensively treated IDDM counterregulate and experience hypoglycemic symptoms at a lower glucose level than conventionally treated patients.
Abstract: Counterregulation and awareness of hypoglycemia begins at lower plasma glucose levels in insulin-dependent diabetes mellitus (IDDM) subjects given intensive insulin treatment. To determine whether these changes are associated with an alteration in the susceptibility of the brain to mild hypoglycemia, we compared central nervous system responses to hypoglycemia in 8 intensively treated (hemoglobin A1, 8.3 ± 0.2%; normal, <8%) and 11 conventionally treated IDDM patients (hemoglobin A1, 14.6 ± 1.3%) with those in 10 healthy subjects. Plasma glucose was lowered from ∼4.6 mmol/L in 0.5–0.6 steps using the clamp technique. Glucose levels triggering hormonal responses and perception of hypoglycemic symptoms were significantly lower in intensively treated patients compared to their poorly controlled counterparts (P < 0.05), and hormonal responses were suppressed compared to those in healthy controls. Similarly directed changes occurred in the level of circulating glucose required to alter cortical evoked potentia...
47 citations