Neuropsychology of Environmental Navigation in Humans: Review and Meta-Analysis of fMRI Studies in Healthy Participants

In the past 20 years, many studies in the cognitive neurosciences have analyzed human ability to navigate in recently learned and familiar environments by investigating the cognitive processes involved in successful navigation. In this study, we reviewed the main experimental paradigms and made a cognitive-oriented meta-analysis of fMRI studies of human navigation to underline the importance of the experimental designs and cognitive tasks used to assess navigational skills. We performed a general activation likelihood estimation (ALE) meta-analysis of 66 fMRI experiments to identify the neural substrates underpinning general aspects of human navigation. Four individual ALE analyses were performed to identify the neural substrates of different experimental paradigms (i.e., familiar vs. recently learned environments) and different navigational strategies (allocentric vs. egocentric). Results of the general ALE analysis highlighted a wide network of areas with clusters in the occipital, parietal, frontal and temporal lobes, especially in the parahippocampal cortex. Familiar environments seem to be processed by an extended temporal-frontal network, whereas recently learned environments require activation in the parahippocampal cortex and the parietal and occipital lobes. Allocentric strategy is subtended by the same areas as egocentric strategy, but the latter elicits greater activation in the right precuneus, middle occipital lobe and angular gyrus. Our results suggest that different neural correlates are involved in recalling a well-learned or recently acquired environment and that different networks of areas subtend egocentric and allocentric strategies.     

The neural regions sustaining episodic encoding and recognition of objects

In this functional MRI experiment, encoding of objects was associated with activation in left ventrolateral prefrontal/insular and right dorsolateral prefrontal and fusiform regions as well as in the left putamen. By contrast, correct recognition of previously learned objects (R judgments) produced activation in left superior frontal, bilateral inferior frontal, and right cerebellar regions, whereas correct rejection of distractor objects (N judgments) was associated with activation in bilateral prefrontal and anterior cingulate cortices, in right parietal and cerebellar regions, in the left putamen, and in the right caudate nucleus. The R minus N comparison showed activation in the left lateral prefrontal cortex and in bilateral cingulate cortices and precunei, while the N minus R comparison did not reveal any positive signal change. These results support the view that similar regions of the frontal lobe are involved in episodic encoding and retrieval processes, and that the successful episodic retrieval of newly learned objects is mainly based on a frontoparietal network.     

Expert athletes activate somatosensory and motor planning regions of the brain when passively listening to familiar sports sounds

The present functional magnetic resonance imaging study examined the neural response to familiar and unfamiliar, sport and non-sport environmental sounds in expert and novice athletes. Results revealed differential neural responses dependent on sports expertise. Experts had greater neural activation than novices in focal sensorimotor areas such as the supplementary motor area, and pre- and postcentral gyri. Novices showed greater activation than experts in widespread areas involved in perception (i.e. supramarginal, middle occipital, and calcarine gyri; precuneus; inferior and superior parietal lobules), and motor planning and processing (i.e. inferior frontal, middle frontal, and middle temporal gyri). These between-group neural differences also appeared as an expertise effect within specific conditions. Experts showed greater activation than novices during the sport familiar condition in regions responsible for auditory and motor planning, including the inferior frontal gyrus and the parietal operculum. Novices only showed greater activation than experts in the supramarginal gyrus and pons during the non-sport unfamiliar condition, and in the middle frontal gyrus during the sport unfamiliar condition. These results are consistent with the view that expert athletes are attuned to only the most familiar, highly relevant sounds and tune out unfamiliar, irrelevant sounds. Furthermore, these findings that athletes show activation in areas known to be involved in action planning when passively listening to sounds suggests that auditory perception of action can lead to the re-instantiation of neural areas involved in producing these actions, especially if someone has expertise performing the actions.     

The effect of specific test queries on source-monitoring event-related potentials

Source-monitoring decision processes were manipulated during retrieval while event-related potentials (ERPs) were recorded. Words were either seen or heard at study, and memory for modality was measured on two separate yes-no source tests. Decision processes were varied across the two tests by asking participants to respond to leading questions. One leading question asked if the items were seen at study, whereas the second question asked if the items were heard at study (cf., Marsh & Hicks, 1998). Behavioral responses indicated that leading questions altered the way in which memory was evaluated to determine the source of information. Varying the decision processes affected frontal--but not parietal ERPs--indicating that frontal ERPs reflect processing that is used to evaluate activated information. Furthermore, left and right frontal ERP activity was affected by the combination of test query and type of source supporting the hypothesis that both the right and left frontal lobes contribute to memory retrieval processes. The pattern of frontal ERP effects supports the hypothesis that activation in right frontal areas reflect basic decision processes that are used to determine source and that the left frontal lobes are recruited when more systematic processing is required by the test context (cf., Nolde, Johnson, & Raye, 1998b).     

Perceiving age and gender in unfamiliar faces: an fMRI study on face categorization

Efficient processing of unfamiliar faces typically involves their categorization (e.g., into old vs. young or male vs. female). However, age and gender categorization may pose different perceptual demands. In the present study, we employed functional magnetic resonance imaging (fMRI) to compare the activity evoked during age vs. gender categorization of unfamiliar faces. In different blocks, participants performed age and gender classifications for old or young unfamiliar faces (50% female respectively). Both tasks elicited activations in the bilateral fusiform gyri (fusiform face area, FFA) and bilateral inferior occipital gyri (occipital face area, OFA). Importantly, the same stimuli elicited enhanced activation during gender as compared to age categorization. This enhancement was significant in the right FFA and the left OFA, and may be related to increased configural processing. Our findings replicate and extend recent work, and shows that the activation of core components of the face processing network is strongly dependent on task demands.     

Neural dichotomy of word concreteness: a view from functional neuroimaging

Our perception about the representation and processing of concrete and abstract concepts is based on the fact that concrete words are highly imagined and remembered faster than abstract words. In order to explain the processing differences between abstract and concrete concepts, various theories have been proposed, yet there is no unanimous consensus about its neural implication. The present study investigated the processing of concrete and abstract words during an orthography judgment task (implicit semantic processing) using functional magnetic resonance imaging to validate the involvement of the neural regions. Relative to non-words, both abstract and concrete words show activation in the regions of bilateral hemisphere previously associated with semantic processing. The common areas (conjunction analyses) observed for abstract and concrete words are bilateral inferior frontal gyrus (BA 44/45), left superior parietal (BA 7), left fusiform gyrus and bilateral middle occipital. The additional areas for abstract words were noticed in bilateral superior temporal and bilateral middle temporal region, whereas no distinct region was noticed for concrete words. This suggests that words with abstract concepts recruit additional language regions in the brain.     

The role of the ventral and dorsal pathways in reading Chinese characters and English words

Previous literature in alphabetic languages suggests that the occipital-temporal region (the ventral pathway) is specialized for automatic parallel word recognition, whereas the parietal region (the dorsal pathway) is specialized for serial letter-by-letter reading ( [Cohen et al., 2008] and [Ho et al., 2002] ). However, few studies have directly examined the role of the ventral and dorsal pathways in Chinese reading compared to English reading. To investigate this issue, we adopted the degraded word processing paradigm used by Cohen et al. (2008) and compared brain regions involved in the processing of degraded Chinese characters and English words during lexical decision, using functional magnetic resonance imaging (fMRI). The degraded characters/words were created by inserting blank spaces between radicals of Chinese characters or syllables of English polysyllabic words. Generally, the current study replicated the effects of Cohen et al. (2008), showing that in Chinese – like in alphabetic languages – character spacing modulates both ventral (bilateral cuneus, left middle occipital gyrus) and dorsal (left superior parietal lobule and middle frontal gyrus) pathways. In addition, the current study showed greater activation in bilateral cuneus and right lingual gyrus for Chinese versus English when comparing spaced to normal stimuli, suggesting that Chinese character recognition relies more on ventral visual-spatial processing than English word recognition. Interestingly, bilateral cuneus showed monotonic patterns in response to increasing spacing, while the rest of the regions of interest showed non-monotonic patterns, indicating different profiles for these regions in visual-spatial processing.     

A long-term follow-up case study of crossed aphasia assessed by single-photon emission tomography (SPECT), language, and neuropsychological testing

A 65-year-old man with well-defined crossed aphasia secondary to right cerebral infarction 10 years previously was studied for current language and cognitive abilities and regional cerebral blood flow (rCBF) during cognitive activation measured by single-photon emission tomography (SPECT). Reversed hemispheric lateralization was demonstrated by qualitative aspects of the patient's constructional deficits, dominant parietal lobe signs, and absence of the neglect syndrome. Language activation procedures during SPECT produced focal increases in rCBF to both frontal lobes with a phoneme detection task and to right temporal and parietal lobes with a math task. The authors stress the complexities of assessing brain/language mechanisms in vivo and demonstrate variabilities in rCBF during language activation dependent on task selection.     

Auditory language comprehension: an event-related fMRI study on the processing of syntactic and lexical information

The functional specificity of different brain regions recruited in auditory language processing was investigated by means of event-related functional magnetic resonance imaging (fMRI) while subjects listened to speech input varying in the presence or absence of semantic and syntactic information. There were two sentence conditions containing syntactic structure, i.e., normal speech (consisting of function and content words), syntactic speech (consisting of function words and pseudowords), and two word-list conditions, i.e., real words and pseudowords. The processing of auditory language, in general, correlates with significant activation in the primary auditory cortices and in adjacent compartments of the superior temporal gyrus bilaterally. Processing of normal speech appeared to have a special status, as no frontal activation was observed in this case but was seen in the other three conditions. This difference may point toward a certain automaticity of the linguistic processes used during normal speech comprehension. When considering the three other conditions, we found that these were correlated with activation in both left and right frontal cortices. An increase of activation in the planum polare bilaterally and in the deep portion of the left frontal operculum was found exclusively when syntactic processes were in focus. Thus, the present data may be taken to suggest an involvement of the left frontal and bilateral temporal cortex when processing syntactic information during comprehension.     

Auditory language comprehension: an event-related fMRI study on the processing of syntactic and lexical information

The functional specificity of different brain areas recruited in auditory language processing was investigated by means of event-related functional magnetic resonance imaging (fMRI) while subjects listened to speech input varying in the presence or absence of semantic and syntactic information. There were two sentence conditions containing syntactic structure, i.e., normal speech (consisting of function and content words), syntactic speech (consisting of function words and pseudowords), and two word-list conditions, i.e., real words and pseudowords. The processing of auditory language, in general, correlates with significant activation in the primary auditory cortices and in adjacent compartments of the superior temporal gyrus bilaterally. Processing of normal speech appeared to have a special status, as no frontal activation was observed in this case but was seen in the three other conditions. This difference may point toward a certain automaticity of the linguistic processes used during normal speech comprehension. When considering the three other conditions, we found that these were correlated with activation in both left and right frontal cortices. An increase of activation in the planum polare bilaterally and in the deep portion of the left frontal operculum was found exclusively when syntactic processes were in focus. Thus, the present data may be taken to suggest an involvement of the left frontal and bilateral temporal cortex when processing syntactic information during comprehension.     

语言经验对大脑激活的影响：来自第二语言初学者的证据

研究采用功能磁共振成像技术考察语言经验在塑造大脑激活模式中的作用。12名只有很少英语学习经验因而熟练程度很低的小学儿童参与了实验。结果发现,在视觉呈现的押韵判断任务中,英文任务和中文任务共同激活了左侧额下回负责语音加工的脑区。更重要的是,虽然英文任务更难,也更多地激活了双侧的顶叶区域,但是它在额叶诱发的激活强度显著低于中文。这个结果进一步说明第二语言的语音皮层表征是随着学习经验的增加而逐渐发展起来的。     

Right to left hemispheric shift in occipital electroencephalographic responses to repeated Kimura figures

Gordon and Carmon (1976) reported that repeated presentations of an initially novel stimulus were associated with a transfer of cerebral dominance over time (trials) from the right to the left hemisphere. To test the generalizability of these results the proportions of alpha rhythms over the left and right occipital and parietal lobes were measured following the presentation of recurring and nonrecurring complex visual patterns (the Kimura Figures) to the upper or lower, left or right peripheral visual fields. Analysis showed increased electrical activation (as inferred by attenuated proportions of alpha rhythms) of the left occipital lobe but decreased activation of the right occipital lobe. This shift occurred during repeated presentations of the same stimuli but not during single presentations of different novel stimuli. There was no significant shift in this activity over the parietal lobes. These results are consistent with the reports of other researchers who have found a shift of dominant neuroelectrical activity from the right to the left hemisphere as the novelty of a visuospatial stimulus decreases.     

SUPPORT FOR A NEUROPSYCHOLOGICAL MODEL OF SPIRITUALITY IN PERSONS WITH TRAUMATIC BRAIN INJURY

Recent research suggests that spiritual experiences are related to increased physiological activity of the frontal and temporal lobes and decreased activity of the right parietal lobe. The current study determined if similar relationships exist between self‐reported spirituality and neuropsychological abilities associated with those cerebral structures for persons with traumatic brain injury (TBI). Participants included 26 adults with TBI referred for neuropsychological assessment. Measures included the Core Index of Spirituality (INSPIRIT); neuropsychological indices of cerebral structures: temporal lobes (Wechsler Memory Scale‐III), right parietal lobe (Judgment of Line Orientation), and frontal lobes (Trail Making Test, Controlled Oral Word Association Test). As hypothesized, spirituality was significantly negatively correlated with a measure of right parietal lobe functioning and positively correlated (nonsignificantly) with measures of left temporal lobe functioning. Contrary to hypotheses, correlations between spirituality and measures of frontal lobe functioning were zero or negative (and nonsignificant). The data support a neuropsychological model that proposes that spiritual experiences are related to decreased activity of the right parietal lobe, which may be associated with decreased awareness of the self (transcendence) and increased activity of the left temporal lobe, which may be associated with the experience of specific religious archetypes (religious figures and symbols).     

Brain activity differentiates face and object processing in 6-month-old infants.

Event-related potentials were used to determine whether infants, like adults, show differences in spatial and temporal characteristics of brain activation during face and object recognition. Three aspects of visual processing were identified: (a) differentiation of face vs. object (P400 at occipital electrode was shorter latency for faces), (b) recognition of familiar identity (Nc, or negative component, at fronto-temporal electrodes [FTEs] was of larger amplitude for familiar stimuli), and (c) encoding novelty (slow wave at FTEs was larger for unfamiliar stimuli). The topography of the Nc was influenced by category type: Effects of familiarity were limited to the midline and right anterior temporal electrodes for faces but extended to all temporal electrodes for objects. Results show that infants' experience with specific examples within categories and their general category knowledge influence the neural correlates of visual processing.     

Effective brain connectivity in children with reading difficulties during phonological processing

Using Dynamic Causal Modeling (DCM) and functional magnetic resonance imaging (fMRI), we examined effective connectivity between three left hemisphere brain regions (inferior frontal gyrus, inferior parietal lobule, fusiform gyrus) and bilateral medial frontal gyrus in 12 children with reading difficulties (M age=12.4, range: 8.11-14.10) and 12 control children (M age=12.3, range: 8.9-14.11) during rhyming judgments to visually presented words. More difficult conflicting trials either had similar orthography but different phonology (e.g. pint-mint) or similar phonology but different orthography (e.g. jazz-has). Easier non-conflicting trials had similar orthography and phonology (e.g. dime-lime) or different orthography and phonology (e.g. staff-gain). The modulatory effect from left fusiform gyrus to left inferior parietal lobule was stronger in controls than in children with reading difficulties only for conflicting trials. Modulatory effects from left fusiform gyrus and left inferior parietal lobule to left inferior frontal gyrus were stronger for conflicting trials than for non-conflicting trials only in control children but not in children with reading difficulties. Modulatory effects from left inferior frontal gyrus to inferior parietal lobule, from medial frontal gyrus to left inferior parietal lobule, and from left inferior parietal lobule to medial frontal gyrus were positively correlated with reading skill only in control children. These findings suggest that children with reading difficulties have deficits in integrating orthography and phonology utilizing left inferior parietal lobule, and in engaging phonological rehearsal/segmentation utilizing left inferior frontal gyrus possibly through the indirect pathway connecting posterior to anterior language processing regions, especially when the orthographic and phonological information is conflicting.     

Functional brain organization for number processing in pre‐verbal infants

Humans are born with the ability to mentally represent the approximate numerosity of a set of objects, but little is known about the brain systems that sub‐serve this ability early in life and their relation to the brain systems underlying symbolic number and mathematics later in development. Here we investigate processing of numerical magnitudes before the acquisition of a symbolic numerical system or even spoken language, by measuring the brain response to numerosity changes in pre‐verbal infants using functional near‐infrared spectroscopy (fNIRS). To do this, we presented infants with two types of numerical stimulus blocks: number change blocks that presented dot arrays alternating in numerosity and no change blocks that presented dot arrays all with the same number. Images were carefully constructed to rule out the possibility that responses to number changes could be due to non‐numerical stimulus properties that tend to co‐vary with number. Interleaved with the two types of numerical blocks were audio‐visual animations designed to increase attention. We observed that number change blocks evoked an increase in oxygenated hemoglobin over a focal right parietal region that was greater than that observed during no change blocks and during audio‐visual attention blocks. The location of this effect was consistent with intra‐parietal activity seen in older children and adults for both symbolic and non‐symbolic numerical tasks. A distinct set of bilateral occipital and middle parietal channels responded more to the attention‐grabbing animations than to either of the types of numerical stimuli, further dissociating the specific right parietal response to number from a more general bilateral visual or attentional response. These results provide the strongest evidence to date that the right parietal cortex is specialized for numerical processing in infancy, as the response to number is dissociated from visual change processing and general attentional processing.     

The concreteness effect: evidence for dual coding and context availability

The term concreteness effect refers to the observation that concrete nouns are processed faster and more accurately than abstract nouns in a variety of cognitive tasks. Two models have been proposed to explain the neuronal basis of the concreteness effect. The dual-coding theory attributes the advantage to the access of a right hemisphere image based system in addition to a verbal system by concrete words. The context availability theory argues that concrete words activate a broader contextual verbal support, which results in faster processing, but do not access a distinct image based system. We used event-related fMRI to detect the brain regions that subserve to the concreteness effect. We found greater activation in the lower right and left parietal lobes, in the left inferior frontal lobe and in the precuneus during encoding of concrete compared to abstract nouns. This makes a single exclusive theory unlikely and rather suggests a combination of both models. Superior encoding of concrete words in the present study may result from (1) greater verbal context resources reflected by the activation of left parietal and frontal associative areas, and (2) the additional activation of a non-verbal, perhaps spatial imagery-based system, in the right parietal lobe.     

Enhanced right hemisphere activation in the mathematically precocious: A preliminary EEG investigation

A preliminary electroencephalographic (EEG) investigation was conducted to determine if the pattern of hemispheric activation in mathematically precocious youth differs from that of average math ability subjects. Alpha activity at four brain sites (frontal, temporal, parietal, and occipital lobes) over the left and right cerebral hemispheres (LH/RH) was monitored while 12- to 14-year-old, right-handed males: (a) looked at a blank slide (baseline condition), (b) judged which of two chimeric faces was "happier," and (c) determined if a word was a noun or a verb. At baseline, the LH of the precocious group was found to be more active at all four brain sites relative to that of the average ability group. During chimeric face processing, the gifted subjects exhibited a significant reduction in alpha power over the RH, primarily at the temporal lobe, while no such alpha suppression was observed in the average ability subjects. For noun/verb determinations, no significant alpha power reductions were obtained for either group. These electrophysiological data generally corroborate the behavioral findings of O'Boyle and Benbow (1990a) and support their contention that enhanced RH involvement during cognitive processing may be a correlate of mathematical precocity. Moreover, the pattern of activation observed across tasks suggests that the ability to effectively coordinate LH and RH processing resources at an early age may be linked to intellectual giftedness.     

文盲与非文盲汉字字形和语音加工的脑机制

利用功能性磁共振成像(fMRI)技术探讨文盲和非文盲汉字字形和语音加工脑机制的差异。实验1使用汉字字形和图形比较了中国人文盲和非文盲字形加工过程脑机制的左侧差异。实验2使用汉字语音和纯音比较了文盲和非文盲语音加工过程脑机制的双侧差异。结果表明文盲与非文盲汉字字形和语音加工脑机制不同,且非文盲的脑活动强。     

抑郁症的脑结构与功能异常:来自静息态下多模态脑影像的研究证据

传统单一模态、单一分析方法在揭示抑郁症脑机制上存在较多局限;而新近多种模态、多种分析方法的结合可在一定程度上较好地促进对抑郁症脑功能和结构的全面探索、挖掘,可以更加有效地运用和实施于早期辅助诊断、干预治疗当中。因此,本文首先简要介绍了多种模态下的脑影像指标及其分析技术,而后分别从结构及功能神经影像数据融合等方面,概述了抑郁症脑结构和功能的研究现状,发现抑郁症患者存在诸多脑区及相关环路结构及功能的异常。同时,通过对抑郁症多模态研究现状的梳理和总结,结合我们已有的相关前期研究工作,对未来抑郁症等情感障碍的进一步研究工作提出了一些思考和展望。