Midtemporal Regions Research Articles

(1)H-MR spectroscopy is sensitive to subtle effects of perinatal asphyxia.

The authors performed neuropsychological and (1)H-MRS studies in 18 subclinical patients with antecedents of perinatal asphyxia (PA) and in 18 matched control subjects. Patients with PA showed reduced values of N-acetylaspartate (NAA) in both the basal ganglia and the midtemporal region (MTR) and reduced NAA/choline values in the MTR. Neuropsychological testing showed group differences in tasks related to attention and memory. These results indicate persistent dysfunctions in cerebral structures vulnerable to hypoxia and demonstrate the utility of MRS for the long-term evaluation of cerebral sequelae of neonatal asphyxia.

An fMRI Study of Sex Differences in Regional Activation to a Verbal and a Spatial Task

Sex differences in cognitive performance have been documented, women performing better on some phonological tasks and men on spatial tasks. An earlier fMRI study suggested sex differences in distributed brain activation during phonological processing, with bilateral activation seen in women while men showed primarily left-lateralized activation. This blood oxygen level-dependent fMRI study examined sex differences (14 men, 13 women) in activation for a spatial task (judgment of line orientation) compared to a verbal-reasoning task (analogies) that does not typically show sex differences. Task difficulty was manipulated. Hypothesized ROI-based analysis documented the expected left-lateralized changes for the verbal task in the inferior parietal and planum temporale regions in both men and women, but only men showed right-lateralized increase for the spatial task in these regions. Image-based analysis revealed a distributed network of cortical regions activated by the tasks, which consisted of the lateral frontal, medial frontal, mid-temporal, occipitoparietal, and occipital regions. The activation was more left lateralized for the verbal and more right for the spatial tasks, but men also showed some left activation for the spatial task, which was not seen in women. Increased task difficulty produced more distributed activation for the verbal and more circumscribed activation for the spatial task. The results suggest that failure to activate the appropriate hemisphere in regions directly involved in task performance may explain certain sex differences in performance. They also extend, for a spatial task, the principle that bilateral activation in a distributed cognitive system underlies sex differences in performance.

Sex differences in brain-behavior relationships between verbal episodic memory and resting regional cerebral blood flow

Women have better verbal memory, and higher rates of resting regional cerebral blood flow (rCBF). This study examined whether there are also sex differences in the relationship between verbal episodic memory and resting rCBF. Twenty eight healthy right-handed volunteers (14 male, 14 female) underwent a neuropsychological evaluation and a Positron Emission Tomography (PET) 15O-water study. Immediate and delayed recall was measured on the logical memory subtest of the Wechsler Memory Scale — Revised (WMS-R), and on the California Verbal Learning Test (CVLT). Resting rCBF (ml/100 g/min) was calculated for four frontal, four temporal, and four limbic regions of interest (ROIs). Women had better immediate recall on both WMS-R and CVLT tasks. Sex differences in rCBF were found for temporal lobe regions. Women had greater bilateral blood flow in a mid-temporal brain region. There were also sex differences in rCBF correlations with performance. Women produced positive correlations with rCBF laterality in the temporal pole. Greater relative CBF in the left temporal pole was associated with better WMS-R immediate and delayed recall in women only. These results suggest that trait differences in temporal pole brain-behavior relationships may relate to sex differences in verbal episodic memory.

478 Effects of laughter on sleep

Studies of healthy and clinical populations have suggested valence- specific cortical and subcortical neural systems regulating emotions. In a study of 12 normal volunteers, the 133xenon clearance method for measuring regional cerebral blood flow (CBF) was used to study the effects of experimentally controlled mood states on regional brain activity within superficial cortex. CBF was measured with 254 detectors and bolus infusion during a happy mood induction task, a sad mood induction task, a sex differentiation task, and a resting baseline condition. CBF increased during sad and decreased during happy mood induction, relative to the activated (sex differentiation) and the nonactivated (resting) nonemotional control conditions. Increased CBF during sad mood induction was correlated with greater negative mood changes. Conversely, increased CBF was associated with a stronger subjective experience of positive affect during happy mood induction. This suggests that cortical arousal may serve to intensify the conscious experience of emotion. Heart rate accelerated during happy and sad mood induction and during sex differentiation relative to a pretask baseline condition. Some regional specificity of effects was also observed. The occipital temporal region showed higher overall CBF during sad mood induction than during happy mood induction. The only region that showed specific lateralized changes in CBF which differentiated sad from happy states was the frontal pole, with left CBF being higher during sad and lower during happy mood induction relative to right CBF. For sad mood induction, there were significant regional differences among correlations between CBF and self-ratings. These were attributable to higher negative correlations (i.e., higher CBF correlates with negative self-rating) in midtemporal, occipital temporal, and postcentral regions. These correlations did not vary across the 15 regions for happy mood induction. For sad mood induction, heart rate correlated positively with CBF increase and with negative affect. Correlations were opposite for happy mood induction. The results suggest high cortical and autonomic arousal during negative/sad mood and low cortical and high autonomic arousal during positive/happy mood. They underscore the value of integrating emotional experience with physiologic measures in neuroimaging activation studies.

Two Patients with Angelman Syndrome Followed Beyond 20 Years of Age

Purpose: Angelman syndrome is now diagnosed appropriately because of the development of the fluorescence in situ hybridization (FISH) method. We encountered two cases of this syndrome, and the follow‐up studies until adulthood produced some interesting clinical findings. Case Reports: Case 1 was a 23‐year‐old man. Albinism, delayed speech development, hyperactivity, avoidance of eye contact, and hypersalivation were noticed. Cerebral palsy ‐was suspected. He could walk independently by age 2 years but could not speak a single word. At age 3 years, epileptic seizures developed and were observed frequently until age 10 years. At that time, his condition was consistent with epilepsia partialis continua because of tremors of the left hand and a continuation of the electroencephalographic (EEG) findings of spikes on the midtemporal and right central regions. The epileptic attacks were controlled with clonazepam (CZP). A constant happy demeanor has been noticed but outbursts of laughter have not been observed. Diffuse high‐amplitude slow‐wave activity with intermittent spike‐wave discharges, which are the characteristic EEG features of Angelman syndrome, disappeared and spike‐wave‐like discharges over the frontal area were observed thereafter. The present clinical features are severe intellectual disability, happy disposition, clumsy and awkward gait without palsy, oculocutaneous albinism, and semiopened large mouth with protruding tongue and salivation. A chromosomal analysis disclosed 46XYde1(15)(qIl.lql2), and the FISH method detected the deletion of the signal SNRNP.Case 2 was a 20‐year‐old man. Intellectual disability and hyperactivity had been noticed since infancy. Cerebral palsy was suspected. He could walk independently by 3 years and 6 months but could not speak a single word. The initial epileptic seizure occurred at age 2 years and 7 months. However, no seizures were observed after age 9 years. He has had a constant happy demeanor but no outbursts of laughter. At the present, he shows severe intellectual disability, happy disposition, clumsy and awkward gait without palsy, hypopigmented skin color, and semiopened large mouth with protruding tongue and salivation. EEG examination during childhood revealed the characteristic EEG activities of Angelman syndrome, diffuse high‐amplitude slow waves with intermittent spikes. However, at the present, only migratory focal spikes are seen. A chromosomal analysis disclosed 46XY del(l5)(qllq13), and the FISH method revealed a deletion of the SNRNP region. Conclusions: We followed up two patients with Angelman syndrome who were diagnosed with the FISH method. Patients with severe intellectual disability and a constant happy demeanor should be studied with the FISH method. Epileptic attacks were well controlled after adolescence, and the characteristic diffuse high‐amplitude slow‐wave activities disappeared thereafter.

Corpus callosum in Alzheimer's disease and vascular dementia--a quantitative magnetic resonance study.

We investigated atrophic alterations in different regions of the corpus callosum in Alzheimer's disease (AD) and vascular dementia (VD) with respect to clinical changes. 32 patients with AD (NINCDS-ADRDA criteria), 17 patients with VD (NINDS-AIREN criteria) and 13 healthy control subjects were included. 3-D MRI sequences were acquired using a 1.5T MRI scanner. The size of the corpus callosum and its subdivisions was sampled on 5 mid-saggital slices using a personal computer-based software. Total callosal size was significantly reduced in AD but not in VD. Furthermore, the most rostral parts of the corpus callosum were significantly smaller in AD when compared to controls. Again, these changes were not found in patients with VD. Severity of dementia was significantly correlated with the size of the midbody of the corpus callosum in AD. Callosal atrophy in AD may reflect the severity and pattern of cortical neuronal damage occurring mostly in the inferior frontal, anterior parietal and midtemporal regions. Correlations between regional callosal atrophy and severity of dementia indicate that interhemispheric cortico-cortical disconnections may contribute to the dementia syndrome.

Aphasia, partial seizures, and regional epileptiform EEG changes

The relationship of epileptiform activity to episodes of aphasia requires definitive clinical-electroencephalogram (EEG) study. We present a case series of seven right-handed patients with adult-onset, recurrent language disturbance in association with seizures or EEG epileptiform activity. The left posterior speech or nearby association area(s) was involved in each case. In two patients the anterior speech area was probably also affected. On EEG, seizures, periodic lateralized epileptiform discharges (PLEDs) or PLEDs plus patterns were found in the left hemisphere, most commonly in the temporoparietal regions. Etiologies were: cavernous hemangioma (two patients), trauma (two patients), hemorrhage from congophilic angiopathy (one patient), ischemic stroke (one patient), and undetermined (one patient). Localization of lesions: left parietooccipital (one patient), left posterotemporal (one patient), left midtemporal region (one patient), left hippocampal gyrus (one patient), and poorly localized in left cerebral convexity (three patients). Differentiation from nonepileptiform mechanisms was possible using scalp EEG and clinical criteria.

Lateralized Changes in Regional Cerebral Blood Flow during Performance of Verbal and Facial Recognition Tasks: Correlations with Performance and “Effort”

Functional neuroimaging has been used to investigate neural substrates of mnemonic processes, and cerebral blood flow (CBF) measures have been sensitive to activation with memory tasks. Studies of memory with two-dimensional133Xenon clearance techniques found that word and face recognition tasks produced contralateral CBF changes in mid-temporal cortical regions. This study replicated the activation paradigm, expanding to the three-dimensional resolution of positron emission tomography (PET). Word and face recognition, and a control baseline task were administered to 19 healthy right-handed volunteers (11 men, 8 women) during successive 10 min PET15O-water measures of CBF. Quantitative CBF rates were calculated with the arterial input function and the equilibrium model. Redistributions of blood flow were compared across tasks using both absolute and relative (region/whole brain) CBF.Replicating the133Xenon clearance findings, CBF was “appropriately” lateralized during task performance (left–right for words > left–right for faces) in the mid-temporal region. Contrary to predictions, the recognition tasks did not activate expected mesolimbic or prefrontal areas. The task-induced CBF changes also correlated with performance. Bilateral CBF in mid-temporal and parahippocampal gyrus regions of interest correlated with the ability to correctly identify word targets (sensitivity). Left-lateralized CBF in the amygdala and hippocampus correlated with better word sensitivity as well as specificity (ability to correctly reject foils). Complementally, right-lateralized CBF in the parahippocampal gyrus correlated with better face specificity performance. In addition, left-lateralized CBF in the amygdala and right-lateralized CBF in the parahippocampal gyrus and hippocampus correlated with “mental effort” indices (task performance relative to basal ability) for word and face memory tasks, respectively. Thus, whereas this recognition task showed the expected lateralized increase in the mid-temporal region and not in frontal and limbic areas, lateralized activation in some of these areas was associated with better performance. Exploratory analyses on other regions showed lateralized changes in one additional temporal region, the occipital-temporal, and several limbic regions.

Benign rolandic epilepsy: high central and low central subgroups.

The spikes in benign rolandic epilepsy (BRE) typically involve both the central and midtemporal regions as recorded on standard EEG montages, but the seizures are characterized by sensorimotor manifestations that are rarely referrable to the temporal lobe. To study this apparent disparity, we evaluated the field distribution of interictal spikes in 33 BRE patients using closely spaced electrodes (AEEGS 1990) arranged over perisylvian cortex. None of the 33 patients showed maximum negativity in the midtemporal regions (T3/T4). Instead, maximum negativity was evident in the high central region (C3/C4) in 10 children (30.3%) and in the low central region (C5/C6) in 23 (69.7%). Hand involvement was significantly frequent (50%) in the high central group, and drooling with oromotor involvement was a distinctive symptom (65.2%) in the low central group. Our findings indicate that the spikes in patients with BRE are exclusively suprasylvian in origin and correlate with two electroclinical subgroups.

The dynamics of metabolic change following seizures as measured by positron emission tomography with fludeoxyglucose F 18.

To examine the time course of alterations in glucose metabolism in relation to the interval from the last seizure, focus laterality, seizure frequency, and seizure type. Metabolic study with the use of positron emission tomography with fludeoxyglucose F 18. Blinded scan evaluation with use of a standard template. Multivariate regression analysis of positron emission tomographic data. National Institutes of Health Clinical Center, Bethesda, Md. Thirty-two adults with intractable partial epilepsy and lateralized seizure onset documented by video-electroencephalographic monitoring. Normalized metabolic rate for glucose ipsilateral and contralateral to the epileptic focus. The most dramatic changes occurred in inferior temporal regions; the midtemporal region was affected as well. Effects lasting 48 hours were found after both simple and complex partial seizures. The time course was different for the two types of seizures. The inferior temporal metabolic rate ipsilateral to the focus increased compared with the interictal rate during the 24-hour period following simple partial seizures; a nadir occurred in the second 24 hours. The rate then rose to an intermediate level after 48 hours. The relative to an intermediate level after 48 hours. The relative regional increase in ipsilateral metabolism following complex partial seizures persisted for 48 hours before falling. The brain may take longer than 24 hours after a partial seizure to return to its baseline state.

Differential effects of mood on cortical cerebral blood flow: A 133xenon clearance study

Studies of healthy and clinical populations have suggested valence- specific cortical and subcortical neural systems regulating emotions. In a study of 12 normal volunteers, the 133xenon clearance method for measuring regional cerebral blood flow (CBF) was used to study the effects of experimentally controlled mood states on regional brain activity within superficial cortex. CBF was measured with 254 detectors and bolus infusion during a happy mood induction task, a sad mood induction task, a sex differentiation task, and a resting baseline condition. CBF increased during sad and decreased during happy mood induction, relative to the activated (sex differentiation) and the nonactivated (resting) nonemotional control conditions. Increased CBF during sad mood induction was correlated with greater negative mood changes. Conversely, increased CBF was associated with a stronger subjective experience of positive affect during happy mood induction. This suggests that cortical arousal may serve to intensify the conscious experience of emotion. Heart rate accelerated during happy and sad mood induction and during sex differentiation relative to a pretask baseline condition. Some regional specificity of effects was also observed. The occipital temporal region showed higher overall CBF during sad mood induction than during happy mood induction. The only region that showed specific lateralized changes in CBF which differentiated sad from happy states was the frontal pole, with left CBF being higher during sad and lower during happy mood induction relative to right CBF. For sad mood induction, there were significant regional differences among correlations between CBF and self-ratings. These were attributable to higher negative correlations (i.e., higher CBF correlates with negative self-rating) in midtemporal, occipital temporal, and postcentral regions. These correlations did not vary across the 15 regions for happy mood induction. For sad mood induction, heart rate correlated positively with CBF increase and with negative affect. Correlations were opposite for happy mood induction. The results suggest high cortical and autonomic arousal during negative/sad mood and low cortical and high autonomic arousal during positive/happy mood. They underscore the value of integrating emotional experience with physiologic measures in neuroimaging activation studies.

Cerebral blood flow in schizophrenia: Effects of memory processing on regional activation

Regional cerebral blood flow (rCBF) was measured with the 133Xenon clearance technique and a high resolution (254 detectors) scanner during the performance of a verbal and a facial memory task in 18 patients with schizophrenia and 18 sociodemographically matched controls. Patients and controls had comparable resting rCBF, but differed in global and hemispheric rCBF changes induced by the memory tasks. Patients had less global increase, which was relatively higher in the left hemisphere, and this was more pronounced for the verbal task. Although controls showed appropriate laterality changes (L > R for verbal and R > L for facial memory) in the midtemporal region, patients failed to show such a focal pattern. They did not show appropriate laterality change in the midtemporal region, but instead showed such changes in other regions. Patients showed greatest impairment in specificity of verbal recognition performance, and this correlated with severity of hallucinations and delusions. This supports a model of left temporal lobe dysfunction in schizophrenia.

The “Third Rhythm”: Alpha-like Activity over the Midtemporal Region

.In addition to the posterior alpha and the rolandic mu rhythm, there is a third alphoid rhythm, which is located over the midtemporal region. This rhythm cannot be detected in the scalp EEG unless there is a bone defect over the midtemporal region. It is easily demonstrable with epidural electrodes. With the use of magnetoencephalography, the third rhythm is readily recorded through the intact skull.This rhythm is of physiological nature: it is impaired or absent in the presence of major temporal lobe pathology. Its frequency is 8–12/sec and may slow down to 6–7/sec. It is essentially a rhythm of wakefulness, declining (but still lingering on) in drowsiness and early NREM sleep. Its blocking mechanism is still debatable.The third rhythm is likely to arise from the neocortical portions of the midtemporal region. A deep origin in limbic structures is unlikely; this rhythm is not found in depth recordings from limbic structures.

Epileptic Apnea in a Neonate

ABSTRACT.We describe an infant who had epileptic apnea in the newborn period. Response to pain was decreased during the event. The corresponding electrographic phenomena were most marked over the left central and midtemporal regions. A CT scan showed findings compatible with a hemorrhagic infarction in the left temporoparietal region. The seizures responded to phenobar-bitone. The patient has remained seizure free and was neurode-velopmentally normal when assessed at 41 months of age.

Alpha-Like Rhythmical Activity of the Temporal Lobe

In addition to the classical posterior alpha rhythm and Rolandic mu rhythm, a third type of rhythmical activity in alpha- (or sub-alpha-) frequency can be recorded over the temporal lobe and especially over the midtemporal region. This rhythm usually escapes detection in the scalp EEG but is commonly seen over bone defects ("breach rhythm"). With the use of epidural electrodes, however, this rhythm becomes quite prominent and dominates the activity of the temporal lobe unless there is excessive local EEG abnormality and/or pathology. This temporal rhythm lies in the range of 6-11/sec and thus often extends into the theta frequency range. There is no proven blocking effect; this mere fact sets it apart from posterior alpha and Rolandic mu rhythm. It is essentially a rhythm of the waking state but may linger into drowsiness and even into light NREM sleep. It is also separable from the highly controversial frontotemporal "kappa rhythm" of bygone times. EEG recordings from the depth of the temporal lobe (limbic structures) do not demonstrate such a rhythm that is likely to originate from the neocortical portion. Its neurophysiological and psychophysiological significance is enigmatic.

Mid-Temporal Spikes in Childhood EEGs and the Hippocampus

In benign childhood epilepsy, EEGs often show spikes in the mid-temporal region although there is no evidence of brain lesions in this region. In this study, mid-temporal spikes are classified into four types with regard to scalp distribution, and it is hypothesized that these spikes may originate in the hippocampus and then spread to the scalp, mainly by volume conduction. The subjects were 50 children (epileptic and non-epileptic), 2 to 15 years of age, with mid-temporal spikes in EEGs: type 1, unilateral mid-temporal spikes (25 cases); type 2, bilateral synchronous spikes (8 cases); type 3, bilateral synchronous spikes with the two sides having opposite polarities (2 cases); and type 4, bilateral asynchronous spikes (15 cases). Because the pyramidal cells are arranged in the form of a "C" in transverse sections of the hippocampus, scalp distribution of spikes might be explained as follows. If the axis of electrical dipoles in the hippocampus is oblique, the electrical potential will spread unilaterally; if the axis is vertical, the potential will spread bilaterally; if the axis is horizontal, the two sides will have opposite poles. With regard to bilateral asynchronous spikes, the two hippocampi may be involved in generation of the spikes. It is thought that the mid-temporal spikes may be non-specific phenomena resulting from various etiologies.

Mid-temporal spikes in childhood EEGs and the hippocampus

In benign childhood epilepsy, EEGs often show spikes in the mid-temporal region although there is no evidence of brain lesions in this region. In this study, mid-temporal spikes are classified into four types with regard to scalp distribution, and it is hypothesized that these spikes may originate in the hippocampus and then spread to the scalp, mainly by volume conduction. The subjects were 50 children (epileptic and non-epileptic), 2 to 15 years of age, with mid-temporal spikes in EEGs: type 1, unilateral mid-temporal spikes (25 cases); type 2, bilateral synchronous spikes (8 cases); type 3, bilateral synchronous spikes with the two sides having opposite polarities (2 cases); and type 4, bilateral asynchronous spikes (15 cases). Because the pyramidal cells are arranged in the form of a “C” in transverse sections of the hippocampus, scalp distribution of spikes might be explained as follows. If the axis of electrical dipoles in the hippocampus is oblique, the electrical potential will spread unilaterally; if the anxis is vertical, the potential will spread bilaterally; if the axis is horizontal, the two sides will have opposite poles. With regard to bilateral asynchronous spikes, the two hippocampi may be involved in generation of the spikes. It is thought that the mid-temporal spikes may be non-specific phenomena resulting from various etiologies.

Regional brain activity in dyslexic and control children during reading tasks: Visual probe event-related potentials

Event-related potentials (ERPs) elicited by task-irrelevant visual stimuli were recorded from 34 control and 32 dyslexic 10- to 12-year-old boys while they performed silent and oral reading at two levels of difficulty. All subjects were extensively screened for neurological problems, IQ, and sensory acuity. Specific features of the ERPs were affected in amplitude and latency by the experimental variables: group membership, oral vs. silent reading, difficulty level, and recording site (within and between hemispheres). A specific effect of difficulty on the central and parietal ERP was seen in the dyslexics but not the controls. Different patterns of asymmetry were found for the two groups in silent vs. oral reading at midtemporal placements. A marked asymmetry (R > L) was found at the midtemporal region for both groups.

Periodic EEG Patterns Observed in Two Cases With Partial Seizures

Two cases with partial seizure and periodic EEG pattern were reported. Case 1. A 74-year-old woman reveal typical periodic lateralized epileptiform discharges (PLED's) on the right hemisphere. The patient was semicomatous with mild jaundice and epilepsia partialis continua in the left lower limb. Postmortem examination revealed a main metastatic carcinoma of pancreas head origin in the right parietooccipital region. In the right hemisphere, the cortical structures were relatively preserved, but the white matter including the frontal lobe was swollen and its demyelinating changes were observed diffusely. The PLED's might result from an anatomical or functional severance of the cerebral cortex from normal connections with deeper structures. Case 2. A 61-year-old woman, with idiopathic hypoparathyroidism showed partial complex seizure. The EEG revealed an anterior temporal spike focus and slowing in the right hemisphere, corresponding with repetitive seizures of about one minute duration and with several minutes interval. An interictal periodic EEG pattern appeared in the right anterior and mid-temporal region. No cerebral abnormalities were found with other neurological examinations including brain scanning, carotisangiogram, and echoencephalogram. The periodic pattern was assumed as subclinical focal seizure discharges from the right anterior temporal deep structures.

Developmental study of the paroxysmal tracing in the full term neonate (author's transl)

The development of the paroxysmal trace was studied in 13 full term neonates having presented with severe neonatal anoxia. The paroxysmal tracings according to the definition given by by Monod and Dreyfus-Brisac changed between the 10th and 15th days, the bursts of waves being more polymorphic and closer together but the paroxysmal component persisted. Further groups of anterior slow waves symmetrical and limited to the mid temporal region appeared. These patterns disappeared between the 2nd and 3rd month to make way for generalised spikes and resembling hypsarrhythmia beyond the third month.