Central auditory processing impairment in patients with temporal lobe epilepsy

In temporal lobe epilepsy (TLE) there may be functional abnormalities or structural lesions that can manifest as a central auditory processing disorder, which is defined as a disorder in the recognition, discrimination, ordering, grouping, and localization of sounds, with emphasis on the processing of nonspeech sounds. We performed frequency pattern, duration pattern, and dichotic tests in 28 patients with TLE with normal hearing on pure tone audiometry. The scores on the frequency pattern, duration pattern, and dichotic tests were abnormal in 78.6, 57.1, and 20.6% of patients, respectively, with no significant differences with the laterality of TLE. Patients with hippocampal sclerosis performed significantly worse than patients with normal MRI findings in frequency tests. Longer duration of epilepsy is negatively correlated with both the duration pattern and dichotic tests (P<0.05). Our results suggest that patients with TLE may be at risk for impairment of central auditory processing, which is increased in patients with hippocampal sclerosis or a longer duration of epilepsy.     

Impaired conditional discrimination learning in schizophrenia

Learning deficits have repeatedly been found in patients with schizophrenia. Eyelid conditional discrimination learning (ECDL) is a test of discriminative aversive conditioning and places minimal demands on motivation. An ECDL task was used to examine residual and paranoid type individuals with schizophrenia and age- and gender-equivalent healthy controls. In the experiment two differently colored light stimuli were randomly presented. Only one of the stimuli (in reinforced trials) was followed by an aversive airpuff to the cornea, as opposed to unreinforced trials where the stimulus was not followed by an aversive airpuff. Conditioned responses develop to both trial types during the course of the experiment. These conditioned responses consist of reflectory eyelid closures already upon light presentation. The patients showed significantly impaired conditional discrimination learning abilities. There was no significant difference between the results in the two schizophrenia subtypes. Patients failed to increase response frequencies on reinforced trials during the course of the experiment, while controls showed appropriate conditional discrimination ability. Thus the results show an impairment of adequate behavior modification in an aversive conditioning task in individuals with schizophrenia. It is concluded that ECDL might be a trait marker for schizophrenia.     

Impaired baroreflex function in temporal lobe epilepsy

Changes of cardiovascular function are frequent in temporal lobe epilepsy (TLE). The baroreflex – the most important reflex for cardiovascular stability – has not been studied systematically in TLE. We evaluated cardiovascular variability and baroreflex function in TLE. In 22 TLE patients and 20 controls, we continuously monitored heart rate (HR) and blood pressure (BP). Time-domain parameters were derived from recordings at rest and from standard cardiovascular reflex tests. Spectral analysis determined sympathetic and parasympathetic modulation of HR and BP in the low (LF-power) and high frequency range (HF-power). We calculated the relative LF- and HF-powers of HR in relation to the sum of LF- and HF-powers. LF/HF-ratio of HR was assessed as a parameter of sympatheticovagal balance. LF-transfer function gain between BP and HR determined baroreflex function. Time-domain parameters did not differ between TLE patients and controls. Spectral analysis showed decreased absolute LF- and HF-powers but increased relative LF-power and LF/HF-ratio of HR in TLE. LF-transfer function gain between BP and HR was reduced in TLE (p<0.05). The reduction of absolute LF- and HF-powers indicates decreased total autonomic variability in TLE. However, increased relative LF-power and LF/HF-ratio of HR in TLE show a relative increase of sympathetic tone. Most importantly, we demonstrate an impaired baroreflex function in TLE. These cardiovascular autonomic abnormalities may contribute to cardiac arrhythmia in TLE. Received in revised form: 15 February 2006     

Impaired perception of temporal order in auditory extinction

It has been proposed that patients with extinction show a chronic bias of spatial attention towards the ipsilesional side. In this case, the law of 'prior entry' predicts that ipsilesional events should be perceived earlier than physically synchronous contralesional stimuli. In line with this prediction, previous studies have revealed substantial delays of awareness for contralesional visual and tactile events in patients with visual and with tactile extinction. The present study provides evidence that a 'prior entry' bias also occurs in the auditory modality. Patients with auditory extinction perceived two acoustic events (one presented to the left ear, the other to the right ear) as being 'simultaneous' when the contralesional sound was leading by 270 ms. The magnitude of this asynchrony was quite similar to that measured previously in the visual modality. Thus, the pathological delay of awareness for contralesional events may be independent of the sensory modality of the stimuli.     

Number processing in temporal lobe epilepsy

BACKGROUND: Specific cognitive impairments have been found in association with mesial temporal lobe epilepsy (TLE), such as deficits in declarative memory or verbal abilities. No attention has been paid so far to possible deficits in number processing. OBJECTIVE: To investigate deficits in number processing in patients with TLE. METHODS: Numerical abilities were assessed in 28 right handed patients with medically intractable unilateral TLE and in a control group. RESULTS: No differences between patients and controls were found in analogue number processing with Arabic input, in a comparison task, or in simple addition and simple subtraction; however, there were significant group differences in tasks with verbal input, in simple division, in complex mental calculation, in a semantic knowledge task, and in conceptual tasks. Only minor differences were found between patients with right and left TLE. CONCLUSIONS: While numerical deficits may be expected in patients with left sided TLE, it is open for discussion why patients with right sided TLE also show numerical deficits.     

Medial temporal lobe in childhood-onset schizophrenia.

The majority of anatomic and neuroimaging studies in adult-onset schizophrenia demonstrate decreased volumes of the medial temporal lobe when compared with findings in normal individuals. The goal of this study was to investigate the hypothesis that subjects with childhood-onset schizophrenia would show decreased volumes of the medial temporal lobe when compared to normal children. Thirteen children meeting DSM-III-R criteria for schizophrenia (mean age 14.2+/-3.8 years) and 20 normal children (mean age 12.0+/-2.8 years) were investigated. MRI scans were performed on a 1.5-T GE Signa MR scanner using a coronal plane SPGR at 1.4-mm slice thickness. Volumes were assessed by manually tracing bilateral hippocampus, amygdala and temporal lobes. After adjustment for age and total brain volume, the amygdala was significantly larger in the schizophrenics than in the control subjects, and this volume increase was more pronounced on the left side. Hippocampus volumes did not differ significantly across groups. There was a nearly significant left-greater-than-right asymmetry of the amygdala in the schizophrenic group but not in the normal group. A nearly significant right-greater-than-left asymmetry was found in the anterior hippocampus for both schizophrenic and control groups. These findings are consistent with previous reports of at least initial sparing of temporal lobe regions in childhood-onset schizophrenia.     

Auditory temporal processing in patients with temporal lobe epilepsy

ObjectiveAuditory temporal processing is the main feature of speech processing ability. Patients with temporal lobe epilepsy, despite their normal hearing sensitivity, may present speech recognition disorders. The present study was carried out to evaluate the auditory temporal processing in patients with unilateral TLE.Materials and methodsThe present study was carried out on 25 patients with epilepsy: 11 patients with right temporal lobe epilepsy and 14 with left temporal lobe epilepsy with a mean age of 31.1 years and 18 control participants with a mean age of 29.4 years. The two experimental and control groups were evaluated via gap-in-noise and duration pattern sequence tests. One-way ANOVA was run to analyze the data.ResultsThe mean of the threshold of the GIN test in the control group was observed to be better than that in participants with LTLE and RTLE. Also, it was observed that the percentage of correct responses on the DPS test in the control group and in participants with RTLE was better than that in participants with LTLE.ConclusionPatients with TLE have difficulties in temporal processing. Difficulties are more significant in patients with LTLE, likely because the left temporal lobe is specialized for the processing of temporal information.     

Impaired discrimination between imagined and performed actions in schizophrenia

The main aim of the present study was to investigate whether a specific type of source monitoring, namely self-monitoring for actions (differentiation between imagined and performed actions), is disrupted in schizophrenia. Persons diagnosed with schizophrenia (n=32) and healthy participants (n=32) were assessed with an action memory task. Simple actions were presented to the participants either verbally (short instructions) or nonverbally (icons). Some of the items required participants to physically perform the action whereas other actions had to be imagined. In the recognition phase of the study, participants were asked whether an action was previously displayed (verbally or nonverbally), whether it was a new action (not presented before), and if they had performed or imagined the action. In addition, participants were asked how confident they were in their decision. Participants in the group with schizophrenia significantly more often misattributed imagined actions as performed and vice versa and were more convinced about their wrong decision than participants in the control group. Patients revealed worse recognition for both verbal and nonverbal actions. In accordance with prior studies, we found that patients were less confident in their correct answers than healthy subjects. However, no enhanced confidence in incorrect answers was found. There was no observed significant relationship between source misattributions and the severity of psychopathological symptoms. Our findings suggest tentatively general source monitoring deficits in schizophrenia.     

Cerebral activation during speech discrimination in temporal lobe epilepsy

Eight patients with uncontrolled complex partial seizures underwent positron emission tomography with 18-fluoro-2-deoxyglucose both at rest and during an auditory order discrimination task using speech syllables. Eight age-matched controls were scanned under identical conditions; an additional 18 normal subjects were scanned only at rest. No consistent task-related changes were seen in control subjects. For the 3 patients with left temporal epileptogenic foci, left inferior temporal lobe hypometabolism was more evident during the activated than during the resting scan. Activation procedures may augment the diagnostic yield of metabolic scanning in epilepsy.     

Impaired fronto-temporal processing of emotion in schizophrenia.

AIMS: Abnormal emotion processing in schizophrenia affects social and functional outcome. Spatiotemporal brain mechanisms underlying this deficit are unclear. MATERIALS AND METHODS: Event-related potential (ERP) responses to emotional and neutral face processing during an implicit (gender detection) and an explicit (expression detection) task were compared between a group of healthy volunteers (n=10) and a group of patients with schizophrenia (n=10). RESULTS: Whereas patients had normal primary visual cortex responses, the early modulation of occipital, temporal, and frontal responses by emotional expression observed in controls was absent in patients. The occipito-temporal N170 amplitude was reduced in patients relative to controls during expression detection, but not during gender detection. Frontal activity within 180-250ms was reduced in patients compared to controls. As opposed to controls, no significant difference was seen in patients at the right temporal electrode (T6) between amplitudes of long-latency ERPs elicited by distinct emotions during the expression detection task. CONCLUSION: In patients with schizophrenia, abnormal early extraction of expression-related information in the occipito-temporal cortex (before 170ms) impairs structural encoding of facial expressions (N170) and may disrupt motivation- and task-dependent context processing (180-250ms time window) of expression-related facial features. Moreover, top-down neuromodulation from frontal and limbic structures to visual occipito-temporal cortex may not be sufficient to optimize the extraction of expression-specific face features.     

Abnormal neurochemical asymmetry in the temporal lobe of schizophrenia

Neuroanatomical asymmetries are known to be present in the human brain, and loss of reversal of these asymmetries, particularly through changes in the left temporal lobe, have been found in the brains of patients with schizophrenia. In addition to disturbed neuroanatomical asymmetries, disturbed neurochemical asymmetries have also been reported in the brains of patients with schizophrenia. However, in the temporal lobe, the laterality of most of these neurochemical changes has not been specifically evaluated. Few neurochemical studies have addressed left-right differences in the superior temporal gyrus (STG). A deteriorated serotonin2A receptor-G protein qalpha (Gqalpha)-phosphoinositide-specific phospholipase C beta1(PLC beta1) cascade has been found in the left, but not right, STG of patients with schizophrenia. Not only neuroanatomical but also neurochemical evidence supports the loss or reversal of normal asymmetry of the temporal lobe in schizophrenia, which might be due to a disruption of the neurodevelopmental processes involved in hemispheric lateralization.     

Compromised memory function in schizophrenia and temporal lobe epilepsy

The purpose of this study was to investigate compromised memory function of schizophrenia patients in comparison with temporal lobe epilepsy patients, whose memory impairments result from a clear lesion. The authors hypothesized that schizophrenia patients would show poorer immediate and delayed recall performances in verbal and visual memory tasks. The study sample consisted of a healthy comparison group of 30 subjects and three patient groups comprising 76 schizophrenia patients, 93 left temporal lobe epilepsy patients, and 72 right temporal lobe epilepsy patients. The authors assessed immediate recall, delayed recall, and delayed retention. Tasks were subdivided into two categories (easy and difficult), and then patient memory dysfunction was compared among the memory tests. The authors observed material-specific memory impairment, where the left temporal lobe epilepsy group showed severe verbal memory impairment and the right temporal lobe epilepsy group showed severe visual memory impairment. A moderate impairment was found in immediate and delayed verbal memory in schizophrenia patients, and the impairment of visual memory was amplified with delayed recall. Such a result can be interpreted not only as a generalized cognitive deficit, but also as an integrative dysfunction involving the mesial temporal and frontal lobes in the left and right hemispheres, whereby the lesion site cannot be determined selectively. Our results show that the selection of a memory task that cannot be influenced by verbal mediation is very important for analyzing memory dysfunction in schizophrenia patients.     

Somatosensory processing is impaired in temporal lobe epilepsy

PURPOSE: Growing evidence suggests that temporal lobe epilepsy (TLE) is a network disease. In this view, the seizure focus may produce measurable deficits in specific cortical functions. METHODS: A tactile grating orientation (GrOr) discrimination task associated with parietal lobe function was administered at the index fingertip to 15 subjects with medically intractable TLE and to 19 neurologically normal controls. TLE subjects were tested bilaterally at baseline while taking their usual antiepileptic drugs (AEDs), and off AEDs during inpatient video-EEG monitoring (n = 9). Three subjects also were tested after temporal lobectomy. t Tests were used to compare baseline performance between TLE subjects and controls, and between hands ipsilateral and contralateral to side of seizure onset, with Bonferroni correction for multiple comparisons. TLE subjects' baseline thresholds were compared with those obtained off AEDs by using a repeated measures analysis of variance. RESULTS: TLE subjects were severely impaired bilaterally on the GrOr task, with mean discrimination thresholds nearly twice those of controls (p 相似文献   

Atypical processing of auditory temporal complexity in autistics

Autistics exhibit a contrasting combination of auditory behavior, with enhanced pitch processing abilities often coexisting with reduced orienting towards complex speech sounds. Based on an analogous dissociation observed in vision, we expected that autistics’ auditory behavior with respect to complex sound processing may result from atypical activity in non-primary auditory cortex. We employed fMRI to explore the neural basis of complex non-social sound processing in 15 autistic and 13 non-autistics, using a factorial design in which auditory stimuli varied in spectral and temporal complexity. Spectral complexity was modulated by varying the harmonic content, whereas temporal complexity was modulated by varying frequency modulation depth. The detection task was performed similarly by autistics and non-autistics. In both groups, increasing spectral or temporal complexity was associated with activity increases in primary (Heschl's gyrus) and non-primary (anterolateral and posterior superior temporal gyrus) auditory cortex Activity was right-lateralized for spectral and left-lateralized for temporal complexity. Increasing temporal complexity was associated with greater activity in anterolateral superior temporal gyrus in non-autistics and greater effects in Heschl's gyrus in autistics. While we observed similar hierarchical functional organization for auditory processing in both groups, autistics exhibited diminished activity in non-primary auditory cortex and increased activity in primary auditory cortex in response to the presentation of temporally, but not of spectrally complex sounds. Greater temporal complexity effects in regions sensitive to acoustic features and reduced temporal complexity effects in regions sensitive to more abstract sound features could represent a greater focus towards perceptual aspects of speech sounds in autism.     

Impaired auditory frequency discrimination in dyslexia detected with mismatch evoked potentials

Deficits in phonological skills appear to be at the heart of reading disability; however, the nature of this impairment is not yet known. The hypothesis that dyslexic subjects are impaired in auditory frequency discrimination was tested by using an attention-independent auditory brain potential, termed mismatch negativity (MMN) while subjects performed a visual distractor task. In separate blocks, MMN responses to graded changes in tone frequency or tone duration were recorded in 10 dyslexic and matched control subjects. MMN potentials to changes in tone frequency but not to changes in tone duration were abnormal in dyslexic subjects. This physiological deficit was corroborated by a similarly specific impairment in discriminating tone frequency, but not tone duration, which was assessed separately. Furthermore, the pitch discrimination and MMN deficit was correlated with the degree of impairment in phonological skills, as reflected in reading errors of regular words and nonwords. It is possible that in dyslexia a persistent sensory deficit in monitoring the frequency of incoming sound may impair the feedback control necessary for the normal development of phonological skills.     

Longitudinal progression of frontal and temporal lobe changes in schizophrenia

On August 5-7, 2011, S?o Paulo was home to the first regional meeting of the Schizophrenia International Research Society (SIRS). Over 400 people from many countries attended the activities and contributed with around 200 submissions for oral and poster presentations. This article summarizes the data presented during the meeting, with an emphasis on the plenary talks and sessions for short oral presentations. For information on the poster presentations, readers are referred to the special issue of Revista de Psiquiatria Clínica (Brazil) dedicated to the conference (available at: http://www.hcnet.usp.br/ipq/revista/vol38/s1/).