Anterior Temporal Lobe Structures Research Articles

Experience transforms crossmodal object representations in the anterior temporal lobes.

Combining information from multiple senses is essential to object recognition, core to the ability to learn concepts, make new inferences, and generalize across distinct entities. Yet how the mind combines sensory input into coherent crossmodal representations - the crossmodal binding problem - remains poorly understood. Here, we applied multi-echo fMRI across a 4-day paradigm, in which participants learned three-dimensional crossmodal representations created from well-characterized unimodal visual shape and sound features. Our novel paradigm decoupled the learned crossmodal object representations from their baseline unimodal shapes and sounds, thus allowing us to track the emergence of crossmodal object representations as they were learned by healthy adults. Critically, we found that two anterior temporal lobe structures - temporal pole and perirhinal cortex - differentiated learned from non-learned crossmodal objects, even when controlling for the unimodal features that composed those objects. These results provide evidence for integrated crossmodal object representations in the anterior temporal lobes that were different from the representations for the unimodal features. Furthermore, we found that perirhinal cortex representations were by default biased toward visual shape, but this initial visual bias was attenuated by crossmodal learning. Thus, crossmodal learning transformed perirhinal representations such that they were no longer predominantly grounded in the visual modality, which may be a mechanism by which object concepts gain their abstraction.

The Implications of Moral Neuroscience for Brain Disease: Review and Update.

The last 2 decades have seen an explosion of neuroscience research on morality, with significant implications for brain disease. Many studies have proposed a neuromorality based on intuitive sentiments or emotions aimed at maintaining collaborative social groups. These moral emotions are normative, deontological, and action based, with a rapid evaluation of intentionality. The neuromoral circuitry interacts with the basic mechanisms of socioemotional cognition, including social perception, behavioral control, theory of mind, and social emotions such as empathy. Moral transgressions may result from primary disorders of moral intuitions, or they may be secondary moral impairments from disturbances in these other socioemotional cognitive mechanisms. The proposed neuromoral system for moral intuitions has its major hub in the ventromedial prefrontal cortex and engages other frontal regions as well as the anterior insulae, anterior temporal lobe structures, and right temporoparietal junction and adjacent posterior superior temporal sulcus. Brain diseases that affect these regions, such as behavioral variant frontotemporal dementia, may result in primary disturbances of moral behavior, including criminal behavior. Individuals with focal brain tumors and other lesions in the right temporal and medial frontal regions have committed moral violations. These transgressions can have social and legal consequences for the individuals and require increased awareness of neuromoral disturbances among such individuals with brain diseases.

A Brain Mechanism for Hate.

A Brain Mechanism for Hate.

Face Recognition.

Functional imaging studies, intracranial recordings, and lesion-deficit correlations in neurological patients have produced unique insights into the cognitive mechanisms and neural substrates of face recognition. In this review, we highlight recent advances in the field and integrate data from these complementary lines of research to propose a functional neuroanatomical model of face identity recognition. Rather than being localized to a single specialized cortical region, face recognition is supported by a distributed neural network. Core components of the network include face-selective visual areas in the ventral occipito-temporal cortex, whereas the extended network is comprised of anterior temporal lobe structures involved in the retrieval of multimodal identity-specific knowledge about familiar individuals, the amygdala responsible for generating emotional responses to faces, and prefrontal regions that provide top-down executive control of the recognition process. Damage to different network components results in neuropsychological disorders of face identity processing manifested either as impaired recognition of familiar faces (prosopagnosia, person recognition disorders) or as false recognition/misidentification of unfamiliar faces. Face identity recognition requires the coordinated activity of a large-scale neural network. Neurological damage can compromise the structural/functional integrity of specific network nodes or their connections and give rise to face recognition disorders with distinct clinical features and underlying cognitive mechanisms determined primarily by the location of the lesion.

Female verbal memory advantage in temporal, but not frontal lobe epilepsy

Women show better performance than men on a range of episodic memory tasks. Evidence regarding a neuroanatomical localization of this effect remains ambiguous. It has been suggested that anterior temporal lobe structures are responsible for sex differences in verbal memory, yet temporal lobe epilepsy (TLE) and TLE surgery do not affect women’s verbal memory advantage. Instead, frontal lobe regions may be relevant for female verbal memory superiority, i.e. by enabling more efficient encoding and retrieval strategies in women. The aim of the present study was to investigate whether women’s verbal memory advantage can be found in patients with frontal lobe epilepsy (FLE), and how patients with FLE and those with TLE differ with regard to sex differences in verbal memory. Fifty patients with unilateral FLE (26 women, 24 men) were compared with 183 patients with unilateral TLE (90 women, 93 men) on both verbal learning and delayed memory. We found that women showed better verbal memory than men in the TLE group, but not in the FLE group. In addition, we found that patients with TLE showed worse verbal learning than those with FLE. Our findings support the idea that women’s advantage in verbal memory may be related to frontal lobe function.

The right hemisphere’s contribution to discourse processing: A study in temporal lobe epilepsy

ObjectiveDiscourse skills - in which the right hemisphere has an important role - enables verbal communication by selecting contextually relevant information and integrating it coherently to infer the correct meaning. However, language research in epilepsy has focused on single word analysis related mainly to left hemisphere processing. The purpose of this study was to investigate discourse abilities in patients with right lateralized medial temporal lobe epilepsy (RTLE) by comparing their performance to that of patients with left temporal lobe epilepsy (LTLE). Methods74 pharmacoresistant temporal lobe epilepsy (TLE) patients were evaluated: 34 with RTLE and 40 with LTLE. Subjects underwent a battery of tests that measure comprehension and production of conversational and narrative discourse. Disease related variables and general neuropsychological data were evaluated. ResultsThe RTLE group presented deficits in interictal conversational and narrative discourse, with a disintegrated speech, lack of categorization and misinterpretation of social meaning. LTLE group, on the other hand, showed a tendency to lower performance in logical-temporal sequencing. SignificanceRTLE patients showed discourse deficits which have been described in right hemisphere damaged patients due to other etiologies. Medial and anterior temporal lobe structures appear to link semantic, world knowledge, and social cognition associated areas to construct a contextually related coherent meaning.

Temporal lobe contribution to perceptual function: A tale of three patient groups

There has been growing recognition of the contribution of medial and anterior temporal lobe structures to non-mnemonic functions, such as perception. To evaluate the nature of this contribution, we contrast the perceptual performance of three patient groups, all of whom have a perturbation of these temporal lobe structures. Specifically, we compare the profile of patients with focal hippocampal (HC) lesions, those with more extensive lesions to the medial temporal lobe (MTL) that include HC and perirhinal cortex (PrC), and those with congenital prosopagnosia (CP), whose deficit has been attributed to the disconnection of the anterior temporal lobe from more posterior structures. All participants completed a range of'oddity’ tasks in which, on each trial, they determined which of four visual stimuli in a display was the'odd-one-out’. There were five stimulus categories including faces, scenes, objects (high and low ambiguity) and squares of different sizes. Comparisons were conducted separately for the HC, MTL and CP groups against their matched control groups and then the group data were compared to each other directly. The group profiles were easily differentiable. Whereas the HC group stood out for its difficulty in discriminating scenes and the CP group stood out for its disproportionate difficulty in discriminating faces with milder effects for scenes and high ambiguity objects, the MTL group evinced a more general discrimination deficit for faces, scenes and high ambiguity objects. The group differences highlight distinct profiles for each of the three groups and distinguish the signature perceptual impairments following more extended temporal lobe alterations.In the recent reconsideration of the role of the hippocampus and neocortex, Moscovitch and colleagues (Moscovitch et al., 2016) note that the medial temporal lobe structures play a role in non-mnemonic functions, such as perception, problem solving, decision-making and language. Here, we address this exact issue, specifically with respect to perception, and we dedicate this paper to Morris Moscovitch in recognition of his profound contribution to science, to his students and to his colleagues.

Understandying the right hemisphere’s role in communication abilities: A study in temporal lobe epilepsy patients

Objective: Language research in epilepsy has previously been focused on dominant hemisphere processing. Although communication skills that enable social functioning and in which the right hemisphere has a central role, have remained unexplored. The purpose of this study was to investigate communication abilities in patients with right lateralized medial temporal lobe epilepsy (TLE).Methods: 60 patients with TLE and hippocampal sclerosis candidates for surgical treatment were evaluated: 28 with a right epileptic zone (EZ) (RTLE) and 32 with a left EZ (LTLE). Subjects were underwent a battery to measure: conversational and narrative discourse; prosody; social inference, pragmatic comprehension; verbal fluency; naming and logic-temporal sequencing. Disease related variables and general neuropsychological data were evaluated.Results: RTLE compared to LTLE patients, showed interictal conversational and narrative discourse impairments, a tendency to tangential and disintegrated speech, lack of hierarchical and categorized codification, and misinterpretation of social intention. RTLE showed lower performance in conversational discourse, narrative comprehension retelling and production, idiom expressions’ and indirect speech’s comprehension, social meaning inference, emotional prosody, strategies for lexical and categorization. Otherwise, LTLE group showed lower performance in logical temporal sequencing.Significance: RTLE patients showed deficits which are similar to what has been described in right hemisphere damaged patients, and may be important to evaluate these skills in RTLE patients to detect potential impairments. Medial and anterior temporal lobe structures seem to have a key role in discourse processing as a link between semantic, world knowledge, and social cognition associated areas to construct a contextually related coherent meaning. Objective: Language research in epilepsy has previously been focused on dominant hemisphere processing. Although communication skills that enable social functioning and in which the right hemisphere has a central role, have remained unexplored. The purpose of this study was to investigate communication abilities in patients with right lateralized medial temporal lobe epilepsy (TLE). Methods: 60 patients with TLE and hippocampal sclerosis candidates for surgical treatment were evaluated: 28 with a right epileptic zone (EZ) (RTLE) and 32 with a left EZ (LTLE). Subjects were underwent a battery to measure: conversational and narrative discourse; prosody; social inference, pragmatic comprehension; verbal fluency; naming and logic-temporal sequencing. Disease related variables and general neuropsychological data were evaluated. Results: RTLE compared to LTLE patients, showed interictal conversational and narrative discourse impairments, a tendency to tangential and disintegrated speech, lack of hierarchical and categorized codification, and misinterpretation of social intention. RTLE showed lower performance in conversational discourse, narrative comprehension retelling and production, idiom expressions’ and indirect speech’s comprehension, social meaning inference, emotional prosody, strategies for lexical and categorization. Otherwise, LTLE group showed lower performance in logical temporal sequencing. Significance: RTLE patients showed deficits which are similar to what has been described in right hemisphere damaged patients, and may be important to evaluate these skills in RTLE patients to detect potential impairments. Medial and anterior temporal lobe structures seem to have a key role in discourse processing as a link between semantic, world knowledge, and social cognition associated areas to construct a contextually related coherent meaning.

Right anterior temporal lobe dysfunction underlies theory of mind impairments in semantic dementia

Semantic dementia is a progressive neurodegenerative disorder characterized by the amodal and profound loss of semantic knowledge attributable to the degeneration of the left anterior temporal lobe. Although traditionally conceptualized as a language disorder, patients with semantic dementia display significant alterations in behaviour and socioemotional functioning. Recent evidence points to an impaired capacity for theory of mind in predominantly left-lateralized cases of semantic dementia; however, it remains unclear to what extent semantic impairments contribute to these deficits. Further the neuroanatomical signature of such disturbance remains unknown. Here, we sought to determine the neural correlates of theory of mind performance in patients with left predominant semantic dementia (n=11), in contrast with disease-matched cases with behavioural-variant frontotemporal dementia (n=10) and Alzheimer's disease (n=10), and healthy older individuals (n=14) as control participants. Participants completed a simple cartoons task, in which they were required to describe physical and theory of mind scenarios. Irrespective of subscale, patients with semantic dementia exhibited marked impairments relative to control subjects; however, only theory of mind deficits persisted when we covaried for semantic comprehension. Voxel-based morphometry analyses revealed that atrophy in right anterior temporal lobe structures, including the right temporal fusiform cortex, right inferior temporal gyrus, bilateral temporal poles and amygdalae, correlated significantly with theory of mind impairments in the semantic dementia group. Our results point to the marked disruption of cognitive functions beyond the language domain in semantic dementia, not exclusively attributable to semantic processing impairments. The significant involvement of right anterior temporal structures suggests that with disease evolution, the encroachment of pathology into the contralateral hemisphere heralds the onset of social cognitive deficits in this syndrome.

Radiation dose and incidence of new metastasis in the anterior temporal lobe structures of radiosurgically treated patients

Gamma Knife surgery (GKS) is frequently used to treat patients with metastasis to the brain. Radiosurgery seeks to limit radiation to the brain tissue surrounding the metastatic deposits. In patients with such lesions, a low radiation dose to the eloquent brain may help to prevent adverse effects. In this study the authors aimed to quantify the radiosurgical dose delivered to the anterior temporal structures in cases of metastatic brain lesions. They also evaluated the incidence and timing of new metastases in the anterior temporal lobes (ATLs) in patient cohorts that underwent GKS with or without whole-brain radiation therapy (WBRT). The authors retrospectively analyzed 100 patients with metastatic brain lesions treated with GKS at the University of Virginia Health System. The anterior 5 cm of the temporal lobes and the hippocampi within the ATLs were contoured on the Gamma Knife planning station. Using the dose-volume histogram function in GammaPlan, treatment parameters for the metastases as well as radiation doses to the contoured ATLs and hippocampi were measured. Patients had clinical and MR imaging follow-ups at 3-month intervals. The ATLs and hippocampal regions were evaluated for the formation of new metastases on follow-up imaging. The demographic data--age, sex, Karnofsky Performance Scale score, number of temporal metastases at the time of GKS, total volume of metastatic tumors per patient, and number of intracranial metastatic deposits--were similar in the 2 cohorts. In patients without an ATL metastasis at the time of GKS, the mean maximum, 50% volume, and integral doses of radiation to the anterior temporal structures were very low: 2.6 Gy, 0.6 Gy, and 36.3 mJ in the GKS cohort and 2.1 Gy, 0.6 Gy, and 40.9 mJ in the GKS+WBRT cohort, respectively. Among the ATLs that had not shown a brain metastasis at the time of GKS, 8 of 92 temporal lobes in the GKS cohort and 10 of 89 in the GKS+WBRT cohort demonstrated a new anterior temporal lesion on follow-up MR imaging. Gamma Knife surgery delivered a low dose of background radiation to the ATLs and hippocampi. The incidence of a new ATL metastasis in the GKS cohort was not higher than in the GKS+WBRT cohort. Gamma Knife surgery in the management of brain metastases limits the delivery of radiation to eloquent brain tissue without evidence of an appreciable propensity to develop new metastatic disease in the ATLs or hippocampi. This therapeutic approach may help to avoid unintended neurological dysfunction due to nonspecific delivery of radiation to eloquent brain tissues.

Specialized Elements of Orbitofrontal Cortex in Primates

The orbitofrontal cortex is associated with encoding the significance of stimuli within an emotional context, and its connections can be understood in this light. This large cortical region is architectonically heterogeneous, but its connections and functions can be summarized by a broad grouping of areas by cortical type into posterior and anterior sectors. The posterior (limbic) orbitofrontal region is composed of agranular and dysgranular-type cortices and has unique connections with primary olfactory areas and rich connections with high-order sensory association cortices. Posterior orbitofrontal areas are further distinguished by dense and distinct patterns of connections with the amygdala and memory-related anterior temporal lobe structures that may convey signals about emotional import and their memory. The special sets of connections suggest that the posterior orbitofrontal cortex is the primary region for the perception of emotions. In contrast to orbitofrontal areas, posterior medial prefrontal areas in the anterior cingulate are not multi-modal, but have strong connections with auditory association cortices, brain stem vocalization, and autonomic structures, in pathways that may mediate emotional communication and autonomic activation in emotional arousal. Posterior orbitofrontal areas communicate with anterior orbitofrontal areas and, through feedback projections, with lateral prefrontal and other cortices, suggesting a sequence of information processing for emotions. Pathology in orbitofrontal cortex may remove feedback input to sensory cortices, dissociating emotional context from sensory content and impairing the ability to interpret events.

Temporal lobe lesions and semantic impairment: a comparison of herpes simplex virus encephalitis and semantic dementia

Both herpes simplex virus encephalitis (HSVE) and semantic dementia (SD) typically affect anterior temporal lobe structures. Using voxel-based morphometry (VBM), this study compared the structural damage in four HSVE patients having a semantic deficit particularly affecting knowledge of living things and six SD patients with semantic impairment across all categories tested. Each patient was assessed relative to a group of control subjects. In both patient groups, left anterior temporal damage extended into the amygdala. In patients with HSVE, extensive grey matter loss was observed predominantly in the medial parts of the anterior temporal cortices bilaterally in SD patients the abnormalities extended more laterally and posteriorly in either the left, right or both temporal lobes. Based on a lesion deficit rationale and converging results from several other sources of evidence, we suggest that (i) antero-medial temporal cortex may be important for processing and differentiating between concepts that are 'tightly packed' in semantic space, such as living things, whereas (ii) inferolateral temporal cortex may play a more general role within the semantic system.

Patterns of temporal lobe atrophy in semantic dementia and Alzheimer's disease

Volumetric magnetic resonance imaging analyses of 30 subjects were undertaken to quantify the global and temporal lobe atrophy in semantic dementia and Alzheimer's disease. Three groups of 10 subjects were studied: semantic dementia patients, Alzheimer's disease patients, and control subjects. The temporal lobe structures measured were the amygdala, hippocampus, entorhinal cortex, parahippocampal gyrus, fusiform gyrus, and superior, middle, and inferior temporal gyri. Semantic dementia and Alzheimer's disease groups did not differ significantly on global atrophy measures. In semantic dementia, there was asymmetrical temporal lobe atrophy, with greater left-sided damage. There was an anteroposterior gradient in the distribution of temporal lobe atrophy, with more marked atrophy anteriorly. All left anterior temporal lobe structures were affected in semantic dementia, with the entorhinal cortex, amygdala, middle and inferior temporal gyri, and fusiform gyrus the most severely damaged. Asymmetrical, predominantly anterior hippocampal atrophy was also present. In Alzheimer's disease, there was symmetrical atrophy of the entorhinal cortex, hippocampus, and amygdala, with no evidence of an anteroposterior gradient in the distribution of temporal lobe or hippocampal atrophy. These data demonstrate that there is a marked difference in the distribution of temporal lobe atrophy in semantic dementia and Alzheimer's disease. In addition, the pattern of atrophy in semantic dementia suggests that semantic memory is subserved by anterior temporal lobe structures, within which the middle and inferior temporal gyri may play a key role.

Subcortical and temporal structures in affective disorder and schizophrenia: A magnetic resonance imaging study

Volumetric measurements of subcortical and temporal structures were done on a sample of 54 schizophrenic patients, who were compared with 48 bipolar patients and 47 normal controls. We observed the male schizophrenic patients to have significant enlargement in the putamen and lesser enlargement in the caudate. We found the righ temporal lobe to be larger than the left across all diagnostic groups, although bipolar females failed to have this asymmetry. We did not replicate the finding of decreased hippocampal, amygdala, or temporal lobe volume in our schizophrenic patients. Nor did we find significant differences between or bipolar patients and controls in the structures measured, with the exception of the right hippocampus. Our findings are consistent with a developmental defect in pruning of subcortical brain regions or with a compensatroy synaptic increase secondary to decreased input from other brain regions such as the prefrontal cortex or anterior temporal lobe structures. Coupled with the lack of temporal lobe asymmetry in bipolar females, these findings suggest that different types of genderspecific neurodevelopmental abnormalities may occur in affective versus schizophrenic psychosis, which may reflect the effects of hormonal influences on brain development in predisposed individuals.

P300 in Patients with Unilateral Temporal Lobectomies: The Effects of Reduced Stimulus Quality

The effects of stimulus quality on the amplitude, peak latency, onset latency, and duration of the P300 component of the event-related brain potential were studied in patients with either a left or a right anterior temporal lobectomy and in normal controls. Stimulus quality was reduced by adding "noise" letters to words which signalled either a left or a right hand button press. Consistent with an interpretation that stimulus quality affects the subject's degree of equivocation, P300 peak latency, reaction time, and errors were all inversely related to stimulus quality, whereas P300 amplitude was directly related to stimulus quality. There were no significant differences between normal controls and either patient group for any of the ERP parameters or reaction time. Right temporal lobectomy patients made, however, significantly more errors, particularly on the catch trials, which suggests that they did not process the stimuli as thoroughly and accurately as the subjects in the other two groups. The absence of significant group differences in either the lateral symmetry or overall P300 amplitude extends the evidence against the idea that anterior temporal lobe structures make any substantial contribution to the scalp P300 in a visual discrimination paradigm. Because of observed delays in the onset of P300 in the low-quality stimulus condition, procedures were developed to quantify both P300 onset latency and P300 duration. Reduced stimulus quality significantly increased P300 onset latency whereas P300 duration remained unaffected, indicating that stimulus categorization must occur prior to, and not during, P300.

Supraspan learning in patients with unilateral anterior temporal lobe resections

The present data address the role of the anterior temporal lobe in verbal and visual supraspan learning. Patient subjects had either a left or right standardized temporal lobe resection, which involved extensive removal of mesial temporal lobe structures. Neither patient group showed marked deficits on either the verbal or visual supraspan learning tasks, although an unexpected performance variation occurred. A tendency to mild depression of performance on the verbal supraspan learning task was observed among right temporal-lobectomy patients. Nevertheless, the overall results indicate that anterior temporal lobe structures are not independently critical for supraspan learning. These findings are consistent with a previous report that posterior brain regions are involved in mediating such tasks.