Vicente Iragui

University of California, San Diego | UCSD · Department of Neurosciences

This study explored the relationships among multimodal imaging, clinical features, and language impairment in patients with left temporal lobe epilepsy (LTLE). Fourteen patients with LTLE and 26 controls underwent structural MRI, functional MRI, diffusion tensor imaging, and neuropsychological language tasks. Laterality indices were calculated for...

Objective. Language reorganization in patients with temporal lobe epilepsy (TLE) appears to result from a complex array of clinical and neurobiological factors. This study aimed to explore the relationship among multimodal brain imaging, clinical features, and language impairment in left TLE (LTLE). Method. Fourteen LTLE patients and 26 healthy co...

Verbal memory is the most commonly impaired cognitive domain in patients with temporal lobe epilepsy (TLE). Although damage to the hippocampus and adjacent temporal lobe structures is known to contribute to memory impairment, little is known of the relative contributions of white versus gray matter structures, or whether microstructural versus morp...

Psychiatric co-morbidities in epilepsy are of great concern. The current study investigated the relative contribution of structural and functional connectivity (FC) between medial temporal (MT) and prefrontal regions in predicting levels of depressive symptoms in patients with temporal lobe epilepsy (TLE). Twenty-one patients with TLE [11 left TLE...

Objective/methods: Neuroimaging research has predominantly focused on exploring how cortical or subcortical brain abnormalities are related to language dysfunction in patients with neurological disease through the use of single modality imaging. Still, limited knowledge exists on how various MRI measures relate to each other and to patients' langu...

Resting electroencephalography (EEG) studies have found consistent abnormalities in Alzheimer’s disease (AD) dementia, including mean frequency slowing, EEG complexity reduction, and deceased coherence among brain regions. Several studies of EEG connectivity have also found abnormalities in Mild Cognitive Impairment (MCI) and symptomatic memory com...

Depression is a common comorbidity in temporal lobe epilepsy (TLE) that is thought to have a neurobiological basis. This study investigated the functional connectivity (FC) of medial temporal networks in depression symptomatology of TLE and the relative contribution of structural versus FC measures. Volumetric MRI and functional connectivity MRI (f...

We sought cognitive event-related potential (ERP) biomarkers of "Preclinical Alzheimer's disease" (Pre-AD) using an incidental verbal learning paradigm with high sensitivity to prodromal AD. Seven elderly persons, with normal cognition at the time of ERP recordings, but who showed subsequent cognitive decline or AD pathology at autopsy (n = 5, mean...

The N400 congruity effect (event-related brain potential (ERP) 300-500. ms poststimulus onset to contextually incongruent minus congruent words) generally shows a linear amplitude decrease with normal aging, and an even greater decrease in Alzheimer's dementia. As little is known about N400 effects in Parkinson's disease (PD), we recorded ERPs in 1...

Objective: Resting-state functional connectivity (FC) has revealed marked network dysfunction in patients with temporal lobe epilepsy (TLE) compared to healthy controls. However, the nature and the location of these changes have not been fully elucidated nor confirmed by other methodologies. We assessed the presence of hippocampal FC changes in TL...

This poster was presented at AES 2012 and is the precursor to our publication in Brain Connectivity, which can also be found online.

Background: Adenosine exerts actions in multiple organ systems, and adenosine receptors are a therapeutic target in many development programmes. Objective: The aim of this analysis was to evaluate the safety of rolofylline, an adenosine A(1)-receptor antagonist, in patients with acute heart failure. Methods: The effect of rolofylline was inves...

The objective of this study is to investigate the relationships among frontotemporal fiber tract compromise and task-switching performance in healthy controls and patients with temporal lobe epilepsy (TLE). We performed diffusion tensor imaging (DTI) on 30 controls and 32 patients with TLE (15 left TLE). Fractional anisotropy (FA) was calculated fo...

Past studies reported more widespread structural brain abnormalities in patients with left compared to right temporal lobe epilepsy (TLE), but the profile of these differences remains unknown. This study investigated the relationship between cortical thinning, white matter compromise, epilepsy variables, and the side of seizure onset, in patients w...

To investigate postoperative changes in fiber tract integrity in patients with temporal lobe epilepsy (TLE) following anterior temporal lobectomy (ATL) and to determine whether postoperative changes are 1) stable vs progressive and 2) related to visual field defects. Diffusion tensor imaging (DTI) was obtained in 7 patients with TLE before, 2 month...

Noninvasive imaging plays a pivotal role in lateralization of the seizure focus in presurgical patients with temporal lobe epilepsy (TLE). Our goal was to evaluate the utility of diffusion tensor imaging (DTI) tractography in TLE. Twenty-one patients with TLE (11 right, 10 left TLE) and 21 controls were enrolled. A 1.5T MR imaging scanner was used...

Neural circuits mediating repetition effect for semantically congruous words on functional MRI were investigated in seventeen normal elderly (mean age=70). Participants determined if written words were semantically congruent (50% probability) with spoken statements. Subsequent cued-recall revealed robust explicit memory only for congruous items (83...

PURPOSE We wished to use diffusion tensor imaging (DTI) tractography to quantify the extent of white matter pathology in patients with temporal lobe epilepsy (TLE) compared to controls, and determine if the information could assist in lateralization of the seizure focus in pre-surgical patients. METHOD AND MATERIALS 21 TLE patients with lateralize...

To investigate the relationship between white matter tract integrity and language and memory performances in patients with temporal lobe epilepsy (TLE). Diffusion tensor imaging (DTI) was performed in 17 patients with TLE and 17 healthy controls. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated for six fiber tracts (uncinate fas...

The role of changes in the extracellular potassium concentration [K(+)](o) in epilepsy has remained unclear. Historically, it was hypothesized that [K(+)]( o) is the causal factor for epileptic seizures. This so-called potassium accumulation hypothesis led to substantial debate but subsequently failed to find wide acceptance. However, recent studie...

To determine the validity and utility of using automated subcortical segmentation to identify atrophy of the hippocampus and other subcortical and cerebellar structures in patients with mesial temporal lobe epilepsy (MTLE). Volumetric MRIs were obtained on 21 patients with MTLE (11 right, 10 left) and 21 age- and gender-matched healthy controls. La...

To determine the nature and extent of regional cortical thinning in patients with mesial temporal lobe epilepsy (MTLE). High-resolution volumetric MRIs were obtained on 21 patients with MTLE and 21 controls. Mean cortical thickness was measured within regions of interest and point-by-point across the neocortex using cortical reconstruction and parc...

We sought cognitive event-related potential (ERP) biomarkers of disease progression and subsequent conversion to dementia in mild cognitive impairment (MCI). Two ERP components, the P600 and N400, are sensitive to abnormal episodic/declarative memory and semantic processing. When congruous category-exemplars are repeated, smaller P600s (relative to...

The ability to interpret nonliteral, metaphoric language was explored in patients with frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE), and matched control participants, to determine (1) if patients with FLE were impaired in their interpretations relative to those with TLE and controls, and (2) if disease-related variables (e.g., age o...

We hypothesized that an ERP word repetition paradigm, which reliably elicits and modulates the P600 and N400 components, would be particularly sensitive to the memory deficits and altered synaptic plasticity in mild Alzheimer's disease (AD). The P600 (a late positive component, or 'LPC'), and the N400, are sensitive indices of memory encoding and s...

Vagus nerve stimulation (VNS) for epilepsy has been available in the United States for 8 years. Pivotal randomized, blinded clinical trials leading to FDA approval in patients age 12 and older with refractory partial seizures have not been performed for other age groups or epilepsy syndromes. This practical review takes stock of the current informa...

Patients with frontal-lobe epilepsy (FLE) or temporal-lobe epilepsy (TLE) and matched control participants were given a design fluency test that assessed nonverbal fluency and switching ability. Patients with FLE generated fewer designs in the switching condition relative to the TLE patients and controls, whereas group differences did not emerge in...

Patients with frontal lobe epilepsy (FLE), patients with temporal lobe epilepsy (TLE), and matched controls were administered a test of response inhibition and set shifting (switching) (Color Word Interference Test, CWIT). Patients with FLE were impaired relative to the controls across all conditions of the CWIT, with the FLE patients showing dispr...

Gamma knife surgery (GKS) is a radiation procedure recently used in the treatment of temporal lobe epilepsy (TLE). Preliminary studies have shown significant seizure reductions in patients 8-26 months postprocedure; however, little is known about the effect of GKS on cognitive functioning in TLE. We report neuropsychological data on three patients...

It has been reported that patients with amnesia have a reduced effect of word repetition upon the late positive component of the event related potential (ERP), which peaks at around 600 ms after word onset. To study a word repetition ERP paradigm in subjects with mild cognitive impairment. 14 patients with mild cognitive impairment (mean mini-menta...

We studied 14 patients with well-characterized refractory temporal lobe epilepsy (TLE), 7 with right temporal lobe epilepsy (RTE) and 7 with left temporal lobe epilepsy (LTE), on a word repetition ERP experiment. Much prior literature supports the view that patients with left TLE are more likely to develop verbal memory deficits, often attributable...

Amnesic patients often show improved performance when stimuli are repeated, even in the absence of conscious memory for those stimuli. Although these performance changes are typically attributed to perceptual or motor systems, in some cases they may be related to basic language processing. We examined two neurophysiological measures that vary with...

Examined the semantic aspect of word repetition effects and its relationship to declarative memory in patients with organic memory impairment. EEG data were recorded of the late positive component and the N400 event-related potentials as 12 amnesic patients (aged 28–78 yrs) displaying a variety of disorders heard a category name, viewed a word, the...

Eye movements, eye blinks, cardiac signals, muscle noise, and line noise present serious problems for electroencephalographic (EEG) interpretation and analysis when rejecting contaminated EEG segments results in an unacceptable data loss. Many methods have been proposed to remove artifacts from EEG recordings, especially those arising from eye move...

Despite genetic, morphological and experimental in vivo, data implying fixed abnormalities in patients with absence seizures, attempts to find highly consistent features in the 3-Hz spike-and-wave pattern recorded during sequential seizures from the same subject have been largely unsuccessful. We used a new data decomposition technique called Indep...

To characterize the effects of normal aging on the amplitude, latency and scalp distribution of the N400 congruity effect. Event-related brain potentials (ERPs) were recorded from 72 adults (half of them men) between the ages of 20 and 80 years (12/decade) as they performed a semantic categorization task. Participants listened to spoken phrases (e....

Pervasive electroencephalographic (EEG) artifacts associated with blinks, eye-movements, muscle noise, cardiac signals, and line noise poses a major challenge for EEG interpretation and analysis. Here, we propose a generally applicable method for removing a wide variety of artifacts from EEG records based on an extended version of an Independent Co...

Auditory P300 amplitude reductions are well-established in young adults with schizophrenia. Little is known, however, regarding the P300 in older schizophrenia patients, especially those with late onset. We studied 28 middle-aged and elderly (mean age = 62.7 years) patients [14 with early onset schizophrenia (EOS) and 14 with late onset schizophren...

Auditory P300 amplitude reductions are well-established in young adults with schizophrenia. Little is known, however, regarding the P300 in older schizophrenia patients, especially those with late onset. We studied 28 middle-aged and elderly (mean age=62.7 years) patients [14 with early onset schizophrenia (EOS) and 14 with late onset schizophrenia...

Severe contamination of electroencephalographic (EEG) activity by eye movements, blinks, muscle, heart and line noise is a serious problem for EEG interpretation and analysis. Rejecting contaminated EEG segments results in a considerable loss of information and may be impractical for clinical data. Many methods have been proposed to remove eye move...

Balamuthia mandrillaris, formerly referred to as a leptomyxid ameba, is a free-living ameba that has recently been identified as a cause of meningoencephalitis. Previously, only two genera, Naegleria and Acanthamoeba, were recognized as causes of central nervous system(CNS) infections in humans. In contrast to Naegleria, Balamuthia causes a subacut...

The hypothesis that the intracranial EEG has local structure and short-term non-stationarity is tested with a little-studied measure of non-linear phase coupling, the bicoherence in human subdural and deep temporal lobe probe data from 11 subjects during sleeping, waking and seizure states. This measure of cooperativity estimates the proportion of...

The N400, an event-related brain potential (ERP) sensitive to semantic congruity, has been reported to have increased latency and/or reduced amplitude in young adults with schizophrenia. Little is known, however, regarding the N400 in older schizophrenia patients, especially those with late onset. We studied 18 middle-aged and elderly patients with...

Regional cortical dysfunction associated with epileptogenic activity was predicted from interictal localized abnormal low frequency neuromagnetic activity (ALFMA) using Magnetic Source Imaging (MSI). ALFMA can be detected in patients who show no interictal spikes. A large array biomagnetometer was used in a blinded, rapid screening protocol. The MS...

Retinal microangiopathy associated with HIV infection is usually asymptomatic and escapes detection unless funduscopic examination is performed when evanescent cotton-wool spots are present. The aim of this study was to assess retinal and optic nerve/retrochiasmal function in HIV infection by means of electrophysiologic techniques that are sensitiv...

To assess the effects of normal aging and senile dementia of the Alzheimer's type (SDAT) on semantic analysis of words, we examined the N400 component of the event-related potential (ERP) elicited during the processing of highly constrained (opposites) and less constrained materials (category-category exemplars) in 12 young control subjects, 12 eld...

As a measure of dynamical structure, short-term fluctuations of coherence between 0.3 and 100 Hz in the electroencephalogram (EEG) of humans were studied from recordings made by chronic subdural macroelectrodes 5-10 mm apart, on temporal, frontal, and parietal lobes, and from intracranial probes deep in the temporal lobe, including the hippocampus,...

Subdural recordings from 8 patients and depth recordings from 3 patients via rows of electrodes with 5–10 mm spacing were searched for signs of significant local differentiation of coherence calculated between all possible pairs of loci. EEG samples of 2–4 min were taken during 4 states: alertness, stage 2–3 sleep, light surgical anesthesia permitt...

Event-related brain potentials (ERPs) were recorded from 74 subjects (45 men) between 18 and 82 years of age in a simple visual detection task. On each trial the subject reported the location of a triangular flash of light presented briefly 20 degrees laterally to the left or right visual field or to both fields simultaneously. ERPs to targets exhi...

Neurological function in 159 subjects infected by the human immunodeficiency virus (HIV) who had no neurological symptoms or signs (129 asymptomatic, 30 with ARC/AIDS) was compared to that of 62 controls by means of pattern-reversal evoked potentials (PREPs), brain-stem auditory evoked potentials (BAEPs), median nerve somatosensory evoked potential...

Neurological function in 159 subjects infected by the human immunodeficiency virus (HIV) who had no neurological symptoms or signs (129 asymptomatic, 30 with ARC/AIDS) was compared to that of 62 controls by means of pattern-reversal evoked potentials (PREPs), brain-stem auditory evoked potentials (BAEPs), median nerve somatosensory evoked potential...

We evaluated felbamate (FBM) monotherapy in 111 patients with uncontrolled partial-onset seizures in a multicenter, double-blind, parallel-group trial. During the 56-day baseline period, patients had at least eight partial-onset seizures and received one standard antiepileptic drug (AED) at a therapeutic level; a second AED was allowed if at a subt...

Auditory event-related potentials (ERPs) were recorded from 71 healthy individuals between 18 and 82 years of age during performance of a disjunctive reaction time task in an auditory oddball paradigm. The effects of aging on reaction times and on the latencies, amplitudes, and distributions of each of the main ERP components were examined. No sign...

Patients with acquired immunodeficiency syndrome frequently suffer peripheral neuropathy. We investigated its prevalence and relationship to clinical stage of human immunodeficiency virus (HIV) infection using quantitative sensory testing and nerve conduction testing. Vibratory threshold was determined in the right great toe and index finger of 179...

Patients with acquired immunodeficiency syndrome frequently suffer peripheral neuropathy. We investigated its prevalence and relationship to clinical stage of human immunodeficiency virus (HIV) infection using quantitative sensory testing and nerve conduction testing. Vibratory threshold was determined in the right great toe and index finger of 179...

A detailed neuropsychological evaluation was performed on a patient with an idiopathic cerebellar degenerative disorder. Significant deficits were found in verbal and nonverbal intelligence, verbal associative learning, and visuospatial skills. These deficits were not readily explained by motor control difficulties. In contrast to the patient's mod...

Posterior tibial somatosensory evoked potentials were obtained in a group of cystic fibrosis patients and age-matched controls. A small but significant delay of the lumbar potential and larger delays of the early scalp potentials were observed. These findings are consistent with earlier pathological studies demonstrating involvement of the somatose...

Two patients with simple partial epileptic seizures were able to abate their attacks by vigorous somatosensory stimulation of the body part initially involved by the seizure. In both patients, the seizure symptoms progressed in a marching fashion which suggests a gradual spread of the epileptic discharge from its initial locus to adjacent areas.

The brain-stem auditory evoked potential (BAEP), a sensitive test of the functional status of the neonatal brain, has not been studied in utero since no practical technique for human fetal recording is available. We have developed a simple recording technique which allows continuous monitoring of the fetal AEP during labor. Waves I, III and V of th...

Two patients, ages 51 and 76 years, suddenly developed transcortical motor aphasia combined with pyramidal signs and ataxia of the right extremities that affected the leg more severely than the arm. Computed tomography revealed nonenhancing lucencies in the distribution territory of the left anterior cerebral artery involving the genu of the corpus...

Pattern electroretinograms (PERGs) were recorded in ten subjects employing two varieties of electrodes: a gold foil electrode inserted into the lower fornix, and a gold cup skin electrode overlying the inferior orbit. Recordings were obtained as subjects viewed a checker-board pattern that reversed with a frequency of 2.1 Hz. Check size varied from...

We recorded simultaneous electroretinograms and visual evoked potentials to pattern-reversal stimulus in ten normal subjects employing check sizes subtending 7.5, 15, 30, 60, 120, 240 and 480 min of visual arc. The mean peak latency of the pattern electroretinogram (PERG) b wave decreased logarithmically with increasing check size. The mean peak la...

We recorded pattern-reversal electroretinograms, flash electroretinograms, pattern-reversal visual evoked potentials, and flash visual evoked potentials in 6 patients with clinically diagnosed Alzheimer's disease and 6 age- and sex-matched control subjects. The mean amplitude of the pattern-reversal electroretinogram in the Alzheimer patients was s...

Pattern electroretinograms (PERGs) were recorded in ten subjects employing two varieties of electrodes: a gold foil electrode inserted into the lower fornix, and a gold cup skin electrode overlying the inferior orbit. Recordings were obtained as subjects viewed a checker-board pattern that reversed with a frequency of 2.1 Hz. Check size varied from...

Pattern reversal visual, brain-stem auditory, and short latency median nerve somatosensory evoked potentials (EPs) were evaluated in a prospective study over 4 years in 20 patients with clinically definite sclerosis (MS). Standardized neurological examinations were done at regular intervals and correlated with EP findings. The highest incidence of...

A 48-year-old woman with a Ramsay Hunt syndrome due to herpes zoster had a hearing deficit. Brainstem auditory evoked potentials (BAEPs) localised the site of dysfunction to the ipsilateral eighth nerve. Clinical improvement was associated with improvement of the BAEP. Conventional audiological studies and BAEPs provided no evidence of involvement...

A 49-year-old man with definite multiple sclerosis suffered an episode of right-sided trigeminal neuralgia (TN) of two weeks' duration, unaccompanied by any other clinical symptoms or signs of exacerbation. Serial evoked potentials, obtained before, during, and after TN, demonstrated developing abnormalities in brain-stem auditory evoked potentials...

The relative efficacies of phenobarbital (PB), phenytoin (PHT), carbamazepine (CBZ), and valproic acid (VPA) in the suppression of focal and generalized seizures produced by electrical stimulation of two different cortical sites (areas 3 and 10) were evaluated in the rat. The two cortical sites were distinguished by significantly different dose‐res...

Charles Bouchard, an ambitious and industrious man, was one of Jean Martin Charcot's first pupils. With his mentor's support, he rapidly ascended the academic ladder and became a full professor at the school of medicine in Paris. After Bouchard attained professorship, his relationship with Charcot gradually deteriorated. Their strong personalities,...

Electrographic seizures (EGS) were detected in 13 of 16 asphyxiated neonates who were undergoing continuous electroencephalographic monitoring for detection of evidence of central nervous system injury. five of the 13 neonates with EGS also had periodic lateralized epileptiform discharges (PLEDs). The electrographic characteristics of PLEDs in thes...

To the Editor. —We read with interest the letter by Dr Jacome1 on homolateral ataxia and crural paresis and the reply by Dr Fisher. Actually, the findings in Dr Jacome's patient more closely resemble those in the patient we described as having "capsular ataxic hemiparesis"2 than those in the patient subsequently described by Ichikawa et al,3 since...

Since signed languages utilize visual-gestural channels, their study allows a unique opportunity for insight into the ways language and gesture may be represented in the brain. The separability of apraxia and aphasia for sign language was examined in four deaf signers who had unilateral brain damage, three to the left hemisphere and one to the righ...

Recent advances in the field of sensory evoked potentials (EPs) have allowed assessment of function in regions of the nervous system that were previously inaccessible to noninvasive electrophysiologic study. Pattern visual and brainstem auditory EPs, respectively, are more sensitive to certain optic nerve or posterior fossa lesions than either clin...

Somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded from neck and scalp electrodes in 23 normal adults using cephalic and non-cephalic (knee) references simultaneously. With a cephalic reference, the neck SEP consisted of several 'negative' potentials that had the same latency at all recording locations. Simultaneous re...