Face recognition by normal subjects depends in roughly equal proportions on shape and surface reflectance cues, while object recognition depends predominantly on shape cues. It is possible that developmental prosopagnosics are deficient not in their ability to recognize faces per se, but rather in their ability to use reflectance cues. Similarly, super-recognizers’ exceptional ability with face recognition may be a result of superior surface reflectance perception and memory. We tested this possibility by administering tests of face perception and face recognition in which only shape or reflectance cues are available to developmental prosopagnosics, super-recognizers, and control subjects. Face recognition ability and the relative use of shape and pigmentation were unrelated in all the tests. Subjects who were better at using shape or reflectance cues were also better at using the other type of cue. These results do not support the proposal that variation in surface reflectance perception ability is the underlying cause of variation in face recognition ability. Instead, these findings support the idea that face recognition ability is related to neural circuits using representations that integrate shape and pigmentation information.
Face recognition; face perception; reflectance; pigmentation; shape; super-recognizers
Ventrolateral prefrontal cortex (VLPFC) has long been linked to language production, but the precise mechanisms are still being elucidated. Using neuropsychological case studies, we explored possible sub-specialization within this region for different linguistic and executive functions. Frontal patients with different lesion profiles completed two sequencing tasks, which were hypothesized to engage partially overlapping components. The multi-word priming task tested the sequencing of co-activated representations and the overriding of primed word orders. The sequence reproduction task tested the sequencing of co-activated representations, but did not employ a priming manipulation. We compared patients’ performance on the two tasks to that of healthy, age-matched controls. Results are partially consistent with an anterior-posterior gradient of cognitive control within lateral prefrontal cortex (Koechlin & Summerfield, 2007). However, we also found a stimulus-specific pattern, which suggests that sub-specialization might be contingent on type of representation as well as type of control signal. Isolating such components functionally and anatomically might lead to a better understanding of language production deficits in aphasia.
language production; sequencing; cognitive control; prefrontal cortex; aphasia
The effect of aging on functional network activation associated with task-switching was examined in 24 young (age = 25.2 ± 2.73 years) and 23 older adults (age = 65.2 ± 2.65 years) using functional Magnetic Resonance Imaging (fMRI). The study goals were to (1) identify a network shared by both young and older adults, (2) identify additional networks in each age group, and (3) examine the relationship between the networks identified and behavioral performance in task-switching. Ordinal Trend Covariance Analysis was used to identify the networks, which takes advantage of increasing activation with greater task demand to isolate the network of regions recruited by task-switching. Two task-related networks were found: a shared network that was strongly expressed by both young and older adults and a second network identified in the young data that was residualized from the shared network. Both networks consisted of regions associated with task-switching in previous studies including the middle frontal gyrus, the precentral gyrus, the anterior cingulate, and the superior parietal lobule. Not only was pattern expression of the shared network associated with reaction time in both age groups, the difference in the pattern expression across task conditions (task-switch minus single-task) was also correlated with the difference in RT across task conditions. On the contrary, expression of the young residual network showed a large age effect such that older adults do not increase expression of the network with greater task demand as young adults do and correlation between expression and accuracy was significant only for young adults. Thus, while a network related to RT is preserved in older adults, a different network related to accuracy is disrupted.
brain behavior correlation; fMRI; multivariate analysis; executive control; aging; dual-task
Cortical regions supporting cognitive control and memory judgment are structurally immature in adolescents. Here we studied adolescents (13–15 y.o.) and young adults (20–22 y.o.) using a recognition memory paradigm that modulates cognitive control demands through cues that probabilistically forecast memory probe status. Behaviorally, adolescence was associated with quicker responding in the presence of invalid cues compared to young adulthood. FMRI data demonstrated that while both groups increasingly activated posterior dorsolateral prefrontal (dlPFC), midline, and lateral parietal regions for invalidly compared to validly cued trials, this differential invalid cueing response ended sooner in adolescents, consistent with their generally quicker responding on cued trials. Critically, dlPFC also demonstrated reversed brain-behavior associations across the groups. Increased mean dlPFC activation during invalid cueing was linked to improved performance in young adults, whereas increases within adolescents were linked to impaired performance. Resting state connectivity analysis revealed greater connectivity between dlPFC and episodic retrieval linked regions in young adults relative to adolescents. These data demonstrate that the functional interpretation of dlPFC activation hinges on its physical maturation and suggest that the pattern of behavioral and neural response in adolescents reflects different functional integration of cognitive control and memory systems.
Adolescence; Cueing; Development; Memory; Recognition
Impairment in social communication is one of the diagnostic hallmarks of autism spectrum disorders, and a large body of research has documented aspects of impaired social cognition in autism, both at the level of the processes and the neural structures involved. Yet one of the most common social communicative abilities in everyday life, the ability to judge somebody's emotion from their facial expression, has yielded conflicting findings. To investigate this issue, we used a sensitive task that has been used to assess facial emotion perception in a number of neurological and psychiatric populations. Fifteen high- functioning adults with autism and 19 control participants rated the emotional intensity of 36 faces displaying basic emotions. Every face was rated 6 times - once for each emotion category. The autism group gave ratings that were significantly less sensitive to a given emotion, and less reliable across repeated testing, resulting in overall decreased specificity in emotion perception. We thus demonstrate a subtle but specific pattern of impairments in facial emotion perception in people with autism.
affect recognition; Asperger's syndrome; autism spectrum disorders; facial affect
Sentence comprehension requires processing of argument structure information associated with verbs, i.e. the number and type of arguments that they select. Many individuals with agrammatic aphasia show impaired production of verbs with greater argument structure density. The extent to which these participants also show argument structure deficits during comprehension, however, is unclear. Some studies find normal access to verb arguments, whereas others report impaired ability. The present study investigated verb argument structure processing in agrammatic aphasia by examining event-related potentials associated with argument structure violations in healthy young and older adults as well as aphasic individuals. A semantic violation condition was included to investigate possible differences in sensitivity to semantic and argument structure information during sentence processing. Results for the healthy control participants showed a negativity followed by a positive shift (N400-P600) in the argument structure violation condition, as found in previous ERP studies (Friederici & Frisch, 2000; Frisch, Hahne, & Friederici, 2004). In contrast, individuals with agrammatic aphasia showed a P600, but no N400, response to argument structure mismatches. Additionally, compared to the control groups, the agrammatic participants showed an attenuated, but relatively preserved, N400 response to semantic violations. These data show that agrammatic individuals do not demonstrate normal real-time sensitivity to verb argument structure requirements during sentence processing.
verb argument structure; event related potentials; language-related brain potentials; N400; P600; semantic processing; agrammatic aphasia
Children born preterm are at risk for deficits in language and reading. They are also at risk for injury to the white matter of the brain. The goal of this study was to determine whether performance in language and reading skills would be associated with white matter properties in children born preterm and full-term. Children born before 36 weeks gestation (n=23, mean±SD age 12.5±2.0 years, gestational age 28.7±2.5 weeks, birth weight 1184±431 g) and controls born after 37 weeks gestation (n=19, 13.1±2.1 years, 39.3±1.0 weeks, 3178±413 g) underwent a battery of language and reading tests. Diffusion Tensor Imaging (DTI) scans were processed using Tract-Based Spatial Statistics to generate a core white matter skeleton that was anatomically comparable across participants. Fractional anisotropy (FA) was the diffusion property used in analyses. In the full-term group, no regions of the whole FA-skeleton were associated with language and reading. In the preterm group, regions of the FA-skeleton were significantly associated with verbal IQ, linguistic processing speed, syntactic comprehension, and decoding. Combined, the regions formed a composite map of 22 clusters on 15 tracts in both hemispheres and in the ventral and dorsal streams. ROI analyses in the preterm group found that several of these regions also showed positive associations with receptive vocabulary, verbal memory, and reading comprehension. Some of the same regions showed weak negative correlations within the full-term group. Exploratory multiple regression in the preterm group found that specific white matter pathways were related to different aspects of language processing and reading, accounting for 27–44% of the variance. The findings suggest that higher performance in language and reading in a group of preterm but not full-term children is associated with higher fractional anisotropy of a bilateral and distributed white matter network.
Language; Reading; Prematurity; Preterm; DTI; White matter
In a previous study (Simmons-Stern, Budson, & Ally 2010), we found that patients with Alzheimer’s disease (AD) better recognized visually presented lyrics when the lyrics were also sung rather than spoken at encoding. The present study sought to further investigate the effects of music on memory in patients with AD by making the content of the song lyrics relevant for the daily life of an older adult and by examining how musical encoding alters several different aspects of episodic memory. Patients with AD and healthy older adults studied visually presented novel song lyrics related to instrumental activities of daily living (IADL) that were accompanied by either a sung or a spoken recording. Overall, participants performed better on a memory test of general lyric content for lyrics that were studied sung as compared to spoken. However, on a memory test of specific lyric content, participants performed equally well for sung and spoken lyrics. We interpret these results in terms of a dual-process model of recognition memory such that the general content questions represent a familiarity-based representation that is preferentially sensitive to enhancement via music, while the specific content questions represent a recollection-based representation unaided by musical encoding. Additionally, in a test of basic recognition memory for the audio stimuli, patients with AD demonstrated equal discrimination for sung and spoken stimuli. We propose that the perceptual distinctiveness of musical stimuli enhanced metamemorial awareness in AD patients via a non-selective distinctiveness heuristic, thereby reducing false recognition while at the same time reducing true recognition and eliminating the mnemonic benefit of music. These results are discussed in the context of potential music-based memory enhancement interventions for the care of patients with AD.
Alzheimer’s disease; recognition memory; music; mnemonics; familiarity; recollection
What does it mean to “know” what an object is? Viewing objects from different categories (e.g., tools vs. animals) engages distinct brain regions, but it is unclear whether these differences reflect object categories themselves or the tendency to interact differently with objects from different categories (grasping tools, not animals). Here we test how the brain constructs representations of objects that one learns to name or physically manipulate. Participants learned to name or tie different knots and brain activity was measured whilst performing a perceptual discrimination task with these knots before and after training. Activation in anterior intraparietal sulcus, a region involved in object manipulation, was specifically engaged when participants viewed knots they learned to tie. This suggests that object knowledge is linked to sensorimotor experience and its associated neural systems for object manipulation. Findings are consistent with a theory of embodiment in which there can be clear overlap in brain systems that support conceptual knowledge and control of object manipulation.
Action learning; Object representation; Perception; Neuroimaging; Parietal
The posteromedial cortex (PMC) is strongly linked to episodic memory and age-related memory deficits. The PMC shows deactivations during a variety of demanding cognitive tasks as compared to passive baseline conditions and has been associated with the default-mode of the brain. Interestingly, the PMC exhibits opposite levels of functional MRI activity during encoding (learning) and retrieval (remembering), a pattern dubbed the encoding/retrieval flip (E/R-flip). Yet, the exact role of the PMC in memory function has remained unclear. This review discusses the possible neurofunctional and clinical significance of the E/R-flip pattern. Regarding neurofunctional relevance, we will review four hypotheses on PMC function: (1) the internal orienting account (2) the self-referential processing account (3) the reallocation account and (4) the bottom-up attention account. None of these accounts seem to provide a complete explanation for the E/R-flip pattern in PMC. Regarding clinical relevance, we review work on aging and Alzheimer’s disease, indicating that amyloid deposits within PMC, years before clinical memory deficits become apparent. High amyloid burden within PMC is associated with detrimental influences on memory encoding, in particular, the attenuation of beneficial PMC deactivations. Finally, we discuss functional subdivisions within PMC that help to provide a more precise picture of the variety of signals observed within PMC. Collective data from anatomical, task-related fMRI and resting-state studies all indicate that the PMC is composed of three main regions, the precuneus, retrosplenial, and posterior cingulate cortex, each with a distinct function. We will conclude with a summary of the findings and provide directions for future research.
Episodic memory provides information about the “when” of events as well as “what” and “where” they happened. Using functional imaging, we investigated the domain specificity of retrieval-related processes following encoding of complex, naturalistic events. Subjects watched a 42-min TV episode, and 24 h later, made discriminative choices of scenes from the clip during fMRI. Subjects were presented with two scenes and required to either choose the scene that happened earlier in the film (Temporal), or the scene with a correct spatial arrangement (Spatial), or the scene that had been shown (Object). We identified a retrieval network comprising the precuneus, lateral and dorsal parietal cortex, middle frontal and medial temporal areas. The precuneus and angular gyrus are associated with temporal retrieval, with precuneal activity correlating negatively with temporal distance between two happenings at encoding. A dorsal fronto-parietal network engages during spatial retrieval, while antero-medial temporal regions activate during object-related retrieval. We propose that access to episodic memory traces involves different processes depending on task requirements. These include memory-searching within an organised knowledge structure in the precuneus (Temporal task), online maintenance of spatial information in dorsal fronto-parietal cortices (Spatial task) and combining scene-related spatial and non-spatial information in the hippocampus (Object task). Our findings support the proposal of process-specific dissociations of retrieval.
What-where-when; Precuneus; Hierarchical structure; Cinematographic material; fMRI
The present study employed Dynamic Causal Modeling to investigate the effective functional connectivity between regions of the neural network involved in top-down letter processing. We used an illusory letter detection paradigm in which participants detected letters while viewing pure noise images. When participants detected letters, the response of the right middle occipital gyrus (MOG) in the visual cortex was enhanced by increased feed-backward connectivity from the left inferior frontal gyrus (IFG). In addition, illusory letter detection increased feed-forward connectivity from the right MOG to the left inferior parietal lobules. Originating in the left IFG, this top-down letter processing network may facilitate the detection of letters by activating letter processing areas within the visual cortex. This activation in turns may highlight the visual features of letters and send letter information to activate the associated phonological representations in the identified parietal region.
letter processing; word processing; top-down processing; fMRI; dynamic causal modeling
Dual-process models of recognition memory distinguish between the retrieval of qualitative information about a prior event (recollection), and judgments of prior occurrence based on an acontextual sense of familiarity. fMRI studies investigating the neural correlates of memory encoding and retrieval conducted within the dual-process framework have frequently reported findings consistent with the view that the hippocampus selectively supports recollection, and has little or no role in familiarity-based recognition. An alternative interpretation of these findings has been proposed, however, in which it is argued that the hippocampus supports the encoding and retrieval of ‘strong’ memories, regardless of whether the memories are recollection- or familiarity-based. Here, we describe the findings of eight fMRI studies from our laboratory: one study of source memory encoding, four studies of the retrieval of contextual information, and three studies of continuous recognition. Together, the findings support the proposal that hippocampal activity co-varies with the amount of contextual information about a study episode that is encoded or retrieved, and not with the strength of an undifferentiated memory signal.
episodic memory; familiarity; memory strength; recollection; remember-know
In several previous behavioral studies, we have identified a group of amnestic patients that, behaviorally, appear to exhibit severe deficits in recollection with relative preservation of familiarity-based recognition. However, these studies have relied exclusively on behavioral measures, rather than direct measures of physiology. Event-related potentials (ERPs) have been used to identify putative neural correlates of familiarity- and recollection-based recognition memory, but little work has been done to determine the extent to which these ERP correlates are spared in patients with relatively specific memory disorders. ERP studies of recognition in healthy subjects have indicated that recollection and familiarity are related to a parietal old-new effect characterized as a late positive component (LPC) and an earlier mid-frontal old-new effect referred to as an ‘FN400’, respectively. Here, we sought to determine the extent to which the putative ERP correlates of recollection and familiarity are intact or impaired in these patients. We recorded ERPs in three amnestic patients and six age matched controls while they made item recognition and source recognition judgments. The current patients were able to discriminate between old and new items fairly well, but showed nearly chance-level performance at source recognition. Moreover, whereas control subjects exhibited ERP correlates of memory that have been linked to recollection and familiarity, the patients only exhibited the mid-frontal FN400 ERP effect related to familiarity-based recognition. The results show that recollection can be severely impaired in amnesia even when familiarity-related processing is relatively spared, and they also provide further evidence that ERPs can be used to distinguish between neural correlates of familiarity and recollection.
Recent cognitive research has revealed better source memory performance for familiar relative to novel stimuli. Here we consider two possible explanations for this finding. The source memory advantage for familiar stimuli could arise because stimulus novelty induces attention to stimulus features at the expense of contextual processing, resulting in diminished overall levels of contextual processing at study for novel (vs. familiar) stimuli. Another possibility is that stimulus information retrieved from long-term memory (LTM) provides scaffolding that facilitates the formation of item-context associations. If contextual features are indeed more effectively bound to familiar (vs. novel) items, the relationship between contextual processing at study and subsequent source memory should be stronger for familiar items. We tested these possibilities by applying multi-voxel pattern analysis (MVPA) to a recently collected functional magnetic resonance imaging (fMRI) dataset, with the goal of measuring contextual processing at study and relating it to subsequent source memory performance. Participants were scanned with fMRI while viewing novel proverbs, repeated proverbs (previously novel proverbs that were shown in a pre-study phase), and previously known proverbs in the context of one of two experimental tasks. After scanning was complete, we evaluated participants’ source memory for the task associated with each proverb. Drawing upon fMRI data from the study phase, we trained a classifier to detect on-task processing (i.e., how strongly was the correct task set activated). On-task processing was greater for previously known than novel proverbs and similar for repeated and novel proverbs. However, both within- and across participants, the relationship between on-task processing and subsequent source memory was stronger for repeated than novel proverbs and similar for previously known and novel proverbs. Finally, focusing on the repeated condition, we found that higher levels of hippocampal activity during the pre-study phase, which we used as an index of episodic encoding, led to a stronger relationship between on-task processing at study and subsequent memory. Together, these findings suggest different mechanisms may be primarily responsible for superior source memory for repeated and previously known stimuli. Specifically, they suggest that prior stimulus knowledge enhances memory by boosting the overall level of contextual processing, whereas stimulus repetition enhances the probability that contextual features will be successfully bound to item features. Several possible theoretical explanations for this pattern are discussed.
novelty; repetition; prior knowledge; episodic memory; multi-voxel pattern analysis (MVPA); fMRI
The medial temporal lobes (MTL) play an essential role in episodic memory, and accumulating evidence indicates that two MTL subregions—the perirhinal (PRc) and parahippocampal (PHc) cortices—might have different functions. According to the binding of item and context theory (Eichenbaum et al., 2007; Diana et al., 2007), PRc is involved in processing item information, the target of memory encoding, whereas PHc is involved in processing context information, peripheral information that identifies the circumstances of the episode. Here, we used functional magnetic resonance imaging (fMRI) adaptation to test the roles of different MTL subregions in the processing of item and context information. Participants were scanned while viewing a series of objects. Each object was presented with a unique semantic encoding question that elicited a salient cognitive context. The object picture, the encoding question, both, or neither were immediately repeated. We found that PRc activity was sensitive to repetition of the object but not the encoding question whereas PHc activity was sensitive to repetition of the encoding question but not the object. These data are consistent with the idea that the PRc and PHc are differentially involved in the representation of item and context information and additionally suggest that the role of the PHc extends to nonspatial, cognitive context information.
parahippocampal cortex; perirhinal cortex; adaptation; context; memory
The putative role of the lateral parietal lobe in episodic memory has recently become a topic of considerable debate, owing primarily to its consistent activation for studied materials during functional magnetic resonance imaging studies of recognition. Here we examined the performance of patients with parietal lobe lesions using an explicit memory cueing task in which probabilistic cues (“Likely Old” or “Likely New”; 75% validity) preceded the majority of verbal recognition memory probes. Without cues, patients and control participants did not differ in accuracy. However, group differences emerged during the “Likely New” cue condition with controls responding more accurately than parietal patients when these cues were valid (preceding new materials) and trending towards less accuracy when these cues were invalid (preceding old materials). Both effects suggest insufficient integration of external cues into memory judgments on the part of the parietal patients whose cued performance largely resembled performance in the complete absence of cues. Comparison of the parietal patients to a patient group with frontal lobe lesions suggested the pattern was specific to parietal and adjacent area lesions. Overall, the data indicate that parietal lobe patients fail to appropriately incorporate external cues of novelty into recognition attributions. This finding supports a role for the lateral parietal lobe in the adaptive biasing of memory judgments through the integration of external cues and internal memory evidence. We outline the importance of such adaptive biasing through consideration of basic signal detection predictions regarding maximum possible accuracy with and without informative environmental cues.
Episodic memory; Parietal cortex; Prefrontal cortex; Signal detection; Decision biasing
Humans can attend to different objects independent of their spatial locations. While selecting an object has been shown to modulate object processing in high-level visual areas in occipitotemporal cortex, where/how behavioral importance (i.e., priority) for objects is represented is unknown. Here we examined the patterns of distributed neural activity during an object-based selection task. We measured brain activity with functional magnetic resonance imaging (fMRI), while participants viewed two superimposed, dynamic objects (left- and right-pointing triangles) and were cued to attend to one of the triangle objects. Enhanced fMRI response was observed for the attention conditions compared to a neutral condition, but no significant difference was found in overall response amplitude between two attention conditions. By using multi-voxel pattern classification (MVPC), however, we were able to distinguish the neural patterns associated with attention to different objects in early visual cortex (V1 to hMT+) and lateral occipital complex (LOC). Furthermore, distinct multi-voxel patterns were also observed in frontal and parietal areas. Our results demonstrate that object-based attention has a wide-spread modulation effect along the visual hierarchy and suggest that object-specific priority information is represented by patterned neural activity in the dorsal frontoparietal network.
attention; fMRI; object-based; pattern classification; top-down control
The sensorimotor experiences we gain when performing an action have been found to influence how our own motor systems are activated when we observe others performing that same action. Here we asked whether this phenomenon applies to the observation of gesture. Would the sensorimotor experiences we gain when performing an action on an object influence activation in our own motor systems when we observe others performing a gesture for that object? Participants were given sensorimotor experience with objects that varied in weight, and then observed video clips of an actor producing gestures for those objects. Electroencephalography (EEG) was recorded while participants first observed either an iconic gesture (pantomiming lifting an object) or a deictic gesture (pointing to an object) for an object, and then grasped and lifted the object indicated by the gesture. We analyzed EEG during gesture observation to determine whether oscillatory activity was affected by the observer’s sensorimotor experiences with the object represented in the gesture. Seeing a gesture for an object previously experienced as light was associated with a suppression of power in alpha and beta frequency bands, particularly at posterior electrodes. A similar pattern was found when participants lifted the light object, but over more diffuse electrodes. Moreover, alpha and beta bands at right parieto-occipital electrodes were sensitive to the type of gesture observed (iconic vs. deictic). These results demonstrate that sensorimotor experience with an object affects how a gesture for that object is processed, as measured by the gesture-observer’s EEG, and suggest that different types of gestures recruit the observer’s own motor system in different ways.
EEG; alpha; beta; gesture; sensorimotor experience
Alcoholism (ALC) and HIV-1 infection (HIV) each affects emotional and attentional processes and integrity of brain white matter fibers likely contributing to functional compromise. The highly prevalent ALC+HIV comorbidity may exacerbate compromise. We used diffusion tensor imaging (DTI) and an emotional Stroop Match-to-Sample task in 19 ALC, 16 HIV, 15 ALC+HIV, and 15 control participants to investigate whether disruption of fiber system integrity accounts for compromised attentional and emotional processing. The task required matching a cue color to that of an emotional word with faces appearing between the color cue and the Stroop word in half of the trials. Nonmatched cue-word color pairs assessed selective attention, and face-word pairs assessed emotion. Relative to controls, DTI-based fiber tracking revealed lower inferior longitudinal fasciculus (ilf) integrity in HIV and ALC+HIV and lower uncinate fasciculus (uf) integrity in all three patient groups. Controls exhibited Stroop effects to positive face-word emotion, and greater interference was related to greater callosal, cingulum and ilf integrity. By contrast, HIV showed greater interference from negative Stroop words during color-nonmatch trials, correlating with greater uf compromise. For face trials, ALC and ALC+HIV showed greater Stroop-word interference, correlating with lower cingulate and callosal integrity. Thus, in HIV, conflict resolution was diminished when challenging conditions usurped resources needed to manage interference from negative emotion and to disengage attention from wrongly cued colors (nonmatch). In ALC and ALC+HIV, poorer callosal integrity was related to enhanced emotional interference suggesting curtailed interhemispheric exchange needed between preferentially right-hemispheric emotion and left-hemispheric Stroop-word functions.
DTI-based fiber tractography; attention; emotion; HIV infection; alcoholism
Neural representation of pitch-relevant information at both the brainstem and cortical levels of processing is influenced by language or music experience. However, the functional roles of brainstem and cortical neural mechanisms in the hierarchical network for language processing, and how they drive and maintain experience-dependent reorganization are not known. In an effort to evaluate the possible interplay between these two levels of pitch processing, we introduce a novel electrophysiological approach to evaluate pitch-relevant neural activity at the brainstem and auditory cortex concurrently. Brainstem frequency-following responses and cortical pitch responses were recorded from participants in response to iterated rippled noise stimuli that varied in stimulus periodicity (pitch salience). A control condition using iterated rippled noise devoid of pitch was employed to ensure pitch specificity of the cortical pitch response. Neural data were compared with behavioral pitch discrimination thresholds. Results showed that magnitudes of neural responses increase systematically and that behavioral pitch discrimination improves with increasing stimulus periodicity, indicating more robust encoding for salient pitch. Absence of cortical pitch response in the control condition confirms that the cortical pitch response is specific to pitch. Behavioral pitch discrimination was better predicted by brainstem and cortical responses together as compared to each separately. The close correspondence between neural and behavioral data suggest that neural correlates of pitch salience that emerge in early, preattentive stages of processing in the brainstem may drive and maintain with high fidelity the early cortical representations of pitch. These neural representations together contain adequate information for the development of perceptual pitch salience.
fundamental frequency; pitch encoding; auditory brainstem; frequency-following response; auditory cortex; cortical pitch response; pitch discrimination
Parkinson’s disease is associated with emotional changes including depression, apathy, and anxiety. The current study investigated emotional processing in non-demented individuals with Parkinson disease (PD) using an electrophysiological measure, the centro-parietal late positive potential (LPP). Non-demented patients with Parkinson’s disease (n=17) and healthy control participants (n=16) viewed pleasant, neutral, and unpleasant pictures while EEG was recorded from a 64-channel geodesic net. The Parkinson patients did not differ from controls in terms of early electrophysiological components that index perceptual processing (occipital P100, N150, P250). Parkinson patients, however, showed reduced LPP amplitude specifically when viewing unpleasant, compared to pleasant, pictures as well as when compared to controls, consistent with previous studies suggesting a specific difference in aversive processing between PD patients and healthy controls. Importantly, LPP amplitude during unpleasant picture viewing was most attenuated for patients reporting high apathy. The data suggest that apathy in PD may be related to a deficit in defensive activation, and may be indexed cortically using event-related potentials.
Parkinson’s disease; ERP; Late positive potential; Apathy; Emotion
Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder that starts in childhood and frequently persists in adults. Electrophysiological studies in children with ADHD provide evidence for abnormal performance monitoring processes and the familality of these processes. It is not yet known if this abnormal processing is developmentally stable and shares familial influences with ADHD throughout the lifespan.
We aimed to investigate event-related potential (ERP) indices of performance monitoring and their familiality in adults with ADHD. An arrow flanker task was presented to 21 adults with ADHD, 20 first-degree relatives (fathers) of children with ADHD and 20 controls.
Compared to the controls, both adults with ADHD and parents of children with ADHD displayed significantly weaker error and conflict monitoring, as indexed by the smaller error negativity (Ne) and the N2 components. These two components were highly correlated within each of the three groups (r = 0.53 - 0.65). The groups did not differ on the error positivity (Pe).
These findings closely resemble those previously found in children with ADHD, suggesting that abnormal conflict monitoring and early error processing is developmentally stable in ADHD and shares familial influences with ADHD in adults. The relationship between different indices of performance monitoring may suggest partly common underlying mechanisms or modulators.
Action monitoring; ADHD; adult ADHD; ERP; error negativity; error positivity; N2; endophenotype
Mild cognitive impairment (MCI), defined as episodic memory impairment beyond what is expected in normal aging, is often associated with hippocampal atrophy (HA) and may represent incipient Alzheimer’s disease. However, recent studies suggest that MCI is very heterogeneous and multiple etiologies likely exist. One possibility is small vessel cerebrovascular disease (CVD). Specifically, we hypothesized that white matter hyperintensities(WMH),an MRI marker for CVD, would lead to impairments in executive control processes critical for working memory that may, in turn, result in episodic memory impairment. To test this hypothesis, we examined a group of subjects clinically diagnosed with MCI and used MRI to further subcategorize individuals as either MCI with severe white matter hyperintensities (MCI-WMH) or MCI with severe hippocampal atrophy (MCI-HA). MCI-WMH, MCI-HA, and matched control subjects each performed a battery of working memory and episodic memory tasks. Results showed that MCI-HA and MCI-WMH were equally impaired on the episodic memory task relative to controls, but MCI-WMH were additionally impaired on tests tapping verbal and spatial working memory abilities and attentional control processes. These results suggest that CVD and hippocampal dysfunction are associated with distinct neuropsychological profiles. Although both syndromes are associated with episodic memory deficits, CVD is additionally associated with working memory and executive control deficits. © 2005 Elsevier Ltd. All rights reserved.
Aging; Dementia; White matter hyperintensities; Working memory; Cerebrovascular disease; Hippocampus
Repeat offenders are commonly given more severe sentences than first-time offenders for the same violations. Though this practice makes intuitive sense, the theory behind escalating penalties is disputed in both legal and economic theories. Here we investigate folk intuitions concerning the moral and intentional status of actions performed by people with positive versus negative prior records. We hypothesized that prior record would modulate both moral judgment and mental state reasoning. Subjects first engaged in an economic game with fair (positive prior record) and unfair (negative prior record) competitors and then read descriptions of their competitors’ actions that resulted in either positive or negative outcomes. The descriptions left the competitors’ mental states unstated. We found that subjects judged actions producing negative outcomes as more “intentional” and more “blameworthy” when performed by unfair competitors. Although explicit mental state evaluation was not required, moral judgments in this case were accompanied by increased activation in brain regions associated with mental state reasoning, including predominantly the right temporo-parietal junction (RTPJ). The magnitude of RTPJ activation was correlated with individual subjects’ behavioural responses to unfair play in the game. These results thus provide insight for both legal theory and moral psychology.
Theory of Mind; Moral reasoning; Temporo-parietal junction; Economic game; fMRI