Alexia and agraphia with lesions of the angular and supramarginal gyri: evidence for the disruption of sequential processing

Gerstmann Syndrome in an Elderly Patient: A Case Report Presented with a Complete Tetrad of Symptoms

Gerstmann syndrome, alternatively recognized as angular gyrus syndrome, epitomizes a complex cognitive impairment that has ignited substantial scholarly discourse within the realms of neurology and neuropsychology. The syndrome's original portrayal was, however, changed. It was demonstrated that the manifestation of its symptomatic tetrad, consisting of four main neurological impairments, is not invariably complete and frequently occurs alongside additional cognitive deficits. Furthermore, the precise cerebral localization of Gerstmann syndrome was traditionally posited to be the left angular gyrus; however, studies mention the possible involvement of other eloquent cerebral areas being pathognomonic. This case report delves into the case of an 86-year-old subject who exhibited the quintessential quartet of symptoms initially delineated by Josef Gerstmann, proposing that elderly patients may manifest a predisposition towards presenting the fully characterized symptomatology initially outlined by Gerstmann.

[A case of left posterior cortical atrophy presenting with kana-predominant reading impairment]

The patient was an 85-year-old man with a one-year history of difficulty reading kana. Neuropsychological evaluation revealed kana (phonogram)-selective reading impairment and kanji (ideogram)-dominant writing impairment. MRI revealed significant cerebral atrophy in the left occipital cortex, leading to the clinical diagnosis of posterior cortical atrophy (PCA). Cerebrospinal fluid amyloid β1-42 levels were reduced, and amyloid PET showed accumulation in the posterior cingulate cortex, precuneus, and frontal lobe. In contrast, tau PET showed no accumulation in the atrophied brain areas. Episodes of REM sleep behavior disorder and decreased uptake on meta-iodobenzylguanidine (MIBG) myocardial scintigraphy suggested the involvement of Lewy body pathology. PCA with distinct laterality has been rarely reported, and ‍this is the first case to present Kana-selective reading impairment and Kanji-dominant writing impairment with neurodegenerative background.

Post-stroke Chinese pure alexia: linguistic features and neuropsychological profiles

PURPOSE

Very few cases of Chinese pure alexia have been reported to date. We aim to summarize the linguistic features and neuropsychological profiles of Chinese pure alexia through a case series study.

METHODS

11 consecutive patients with post-stroke Chinese pure alexia and 11 healthy controls were included. The Aphasia Battery of Chinese (ABC) and 68-Chinese character oral reading test (68-character test) were used to evaluate the reading and writing ability. Reading errors were classified based on the performance of 68-character test. Neuropsychological profiles were evaluated with corresponding scales. The possible correlation between the reading ability and the writing ability or neuropsychological performance was analyzed.

RESULTS

The patients had a correct rate of 43.7 ± 23.2% in the 68-character test, significantly lower (P < 0.001) than that of controls. Shape-similar error was the most common type of reading error (101/209, 48.3%). The ABC total writing score rate of the patients ranged from 68.9% to 98.7% (median, 90.5%), significantly lower (P < 0.001) than that of the controls. The patients also showed worse performance in MMSE, auditory verbal learning test, Boston naming test, intersecting pentagons copying and clock-drawing test (all P < 0.05). In the patient group, the correct rate of 68-character test was significantly correlated with the ABC total writing score rate (P = 0.008), the score rate of Boston naming test (P = 0.017), and the clock-drawing test score (P = 0.010).

CONCLUSION

Shape-similar errors may be a characteristic of Chinese pure alexia. The correlation between visuospatial dysfunction and pure alexia might explain the frequent occurrence of shape-similar errors in Chinese pure alexia.

Frontal allographic agraphia in a patient with behavioral variant frontotemporal dementia

We report a patient with behavioral variant frontotemporal dementia who developed agraphia, irritability, perseverative and stereotyped behavior, and dietary changes. MRI revealed bilateral frontal convexity atrophy. Neuropsychological examination showed fluent aphasia with perseverative allographic agraphia, mild semantic impairment, and dysexecutive syndrome. Allographic agraphia featured unidirectional conversion from hiragana (cursive form of Japanese phonograms) and kanji (Japanese morphograms) to katakana (square form of Japanese phonograms), as opposed to mutual (bidirectional) conversion between hiragana and katakana in parieto-occipital gyri lesions. Furthermore, all letters of the word were converted and this whole-word conversion may be characteristic of perseverative behavior in frontotemporal dementia.

Apraxia of speech due to the left postcentral gyrus lesion

Key Clinical Message

Apraxia of speech (AOS) due to a postcentral infarction differs from conventional precentral AOS with respect to phonemic errors (phoneme substitution) which are more common than phonetic errors (phoneme distortion) and preserved accent and intonation.

Abstract

Clinical features of apraxia of speech caused by lesions in the postcentral gyrus have not yet been elucidated. Here, we report a patient with this lesion and show how postcentral apraxia of speech differs from the hitherto known precentral apraxia of speech. A 54-year-old man developed Broca's aphasia with apraxia of speech that resolved into pure apraxia of speech within 3 weeks following infarction of the postcentral gyrus. The diagnosis of apraxia of speech was based on the patient's effortful, slow speech and inconsistent phonetic distortions with phonemic paraphasia. The Western Aphasia Battery was used to examine the patient's speech samples. Speech was recorded using a digital voice recorder and transcribed into a narrow transcription of the International Phonetic Alphabet. The error types were categorized phonologically. The results revealed that (a) phonemic errors (vowel and consonant substitutions, also known as phonemic paraphasia) were more common than phonetic errors (vowel and consonant distortions). Similar to conduction aphasia, phonemic errors were more pronounced in confrontation naming than in repetition, accompanied by self-correction, and (b) word accent and sentence intonation were preserved, although the speech was slow. These two features are characteristic of postcentral apraxia of speech, which can be differentiated from conventional precentral apraxia of speech.

Distinct parallel activation and interaction between dorsal and ventral pathways during phonological and semantic processing: A cTBS-fMRI study

Successful visual word recognition requires the integration of phonological and semantic information, which is supported by the dorsal and ventral pathways in the brain. However, the functional specialization or interaction of these pathways during phonological and semantic processing remains unclear. Previous research has been limited by its dependence on correlational functional magnetic resonance imaging (fMRI) results or causal validation using patient populations, which are susceptible to confounds such as plasticity and lesion characteristics. To address this, the present study employed continuous theta-burst stimulation combined with fMRI in a within-subject design to assess rapid adaptation in regional activity and functional connectivity of the dorsal and ventral pathways during phonological and semantic tasks. This assessment followed the precise inhibition of the left inferior parietal lobule and anterior temporal lobe in the dorsal and ventral pathways, respectively. Our results reveal that both the dorsal and ventral pathways were activated during phonological and semantic processing, while the adaptation activation and interactive network were modulated by the task type and inhibited region. The two pathways exhibited interconnectivity in phonological processing, and disruption of either pathway led to rapid adaptation across both pathways. In contrast, only the ventral pathway exhibited connectivity in semantic processing, and disruption of this pathway alone resulted in adaptive effects primarily in the ventral pathway. These findings provide essential evidence supporting the interactive theory, phonological information processing in particular, potentially providing meaningful implications for clinical populations.

Beyond Broca's and Wernicke's: Functional Mapping of Ancillary Language Centers Prior to Brain Tumor Surgery

Functional MRI is a well-established tool used for pre-surgical planning to help the neurosurgeon have a roadmap of critical functional areas that should be avoided, if possible, during surgery to minimize morbidity for patients with brain tumors (though this also has applications for surgical resection of epileptogenic tissue and vascular lesions). This article reviews the locations of secondary language centers within the brain along with imaging findings to help improve our confidence in our knowledge on language lateralization. Brief overviews of these language centers and their contributions to the language networks will be discussed. These language centers include primary language centers of "Broca's Area" and "Wernicke's Area". However, there are multiple secondary language centers such as the dorsal lateral prefrontal cortex (DLPFC), frontal eye fields, pre- supplemental motor area (pre-SMA), Basal Temporal Language Area (BTLA), along with other areas of activation. Knowing these foci helps to increase self-assurance when discussing the nature of laterality with the neurosurgeon. By knowing secondary language centers for language lateralization, via fMRI, one can feel confident on providing neurosurgeon colleagues with appropriate information on the laterality of language in preparation for surgery.

The Cognitive Makeup of Writing: Multivariate Analysis of Writing Impairments Following Stroke

Writing is a recently acquired skill to human behavioral repertoire, essential in industrialized societies. In the clinic, writing impairment is evident in one-third of stroke patients. This study aimed to find out the cognitive features that contribute to writing impairment of stroke patients in two different writing systems (logographic and phonological). Cognitive profiles were assessed using the Birmingham Cognitive Screen in two cohorts, China (244 patients) and UK (501 patients). The datasets were analyzed separately using an identical procedure. Elastic net was used to rank the importance of different cognitive abilities (features) to writing skill; and linear support vector machine was used to identify the discriminative features needed to accurately identify the stroke patients with and without writing impairments. The prediction performance was evaluated with the area under the curve (AUC), accuracy (ACC), sensitivity (SEN), and specificity (SPE). For the China cohort, writing numbers, complex figure copy, and number calculation obtained good prediction performance on writing impairments with AUC 0.85 ± 0.06, ACC (89 ± 3) %, SEN (81 ± 10) %, and SPE (90 ± 27) %. Concerning the UK data, writing numbers, number calculation, non-word reading, and auditory sustain attention achieved AUC 0.79 ± 0.04, ACC (83 ± 3) %, SEN (74 ± 9) %, and SPE (84 ± 3) %. A small number of patients in both cohorts (China: 9/69, UK: 24/137), who were impaired in writing, were consistently misclassified. Two patients, one in each cohort, showed selective impairments in writing, while all remaining patients were impaired in attention, language, and/or praxis tasks. The results showed that the capability to write numbers and manipulate them were critical features for predicting writing abilities across writing systems. Reading abilities were not a good predictor of writing impairments across both cohorts. Constructive praxis (measured by complex figure copy) was relevant to impairment classification in characters-based writing (China), while phonological abilities (measured by non-word reading) were important features for impairment prediction in alphabetic writing (UK). A small proportion minority of cases with writing deficits were related to different impairment profiles. The findings in this study highlight the multifaceted nature of writing deficits and the potential use of computation methods for revealing hidden cognitive structures in neuropsychological research.

Primary and Secondary Progressive Aphasia in Posterior Cortical Atrophy

Background: Posterior cortical atrophy (PCA) is a clinico-radiological syndrome characterized by a progressive decline in visuospatial/visuoperceptual processing. PCA is accompanied by the impairment of other cognitive functions, including language abilities. Methods: The present study focused on three patients presenting with language complaints and a clinical profile that was compatible with PCA. In addition to neurological and neuroimaging examinations, they were assessed with comprehensive batteries of neuropsychological and neurolinguistic tests. Results: The general medical profile of the three patients is consistent with PCA, although they presented with confounding factors, making diagnosis less clear. The cognitive profile of the three patients was marked by Balint and Gerstmann’s syndromes as well as impairments affecting executive functions, short-term and working memory, visuospatial and visuoperceptual abilities, and sensorimotor execution abilities. Their language ability was characterized by word-finding difficulties and impairments of sentence comprehension, sentence repetition, verbal fluency, narrative speech, reading, and writing. Conclusions: This study confirmed that PCA is marked by visuospatial and visuoperceptual deficits and reported evidence of primary and secondary language impairments in the three patients. The similarities of some of their language impairments with those found in the logopenic variant of primary progressive aphasia is discussed from neurolinguistic and neuroanatomical points of view.

Vascular syndromes: Revisiting classification of poststroke aphasia

Over 150 years have passed since the first formal description of aphasia associated with localized neurologic damage. In the years since that time, a significant amount of research has been conducted to identify/explain the locations and functions of the brain regions responsible for (or associated with) language as well as to describe the various types of aphasia resulting from injury to these locations. Many of these attempts to associate somewhat predictable patterns of language deficits with damage to specific structures have been confounded by atypical reports and considerable variability in either the behavioral presentation and/or structural damage that directly contradict/oppose some of the proposed theories. However, considering the aphasias as vascular syndromes, or a collection of symptoms associated with damage to various structures supplied by a specific artery, accounts for both the predictability and the variability seen. This chapter presents a brief history of aphasia classification, the vascular territories commonly associated with aphasia, the different aphasic vascular syndromes, and the typical recovery/evolution of aphasia presentation over time.

Surviving (but not thriving) after cranial vault trauma: A case study from Transylvania

OBJECTIVE

To link an antemortem cranial injury on the left parietal bone with potential neurocognitive consequences.

MATERIALS

The skeleton of a male individual from a Székely archaeological site in Transylvania was examined. The skeleton was radiocarbon dated to Cal AD 1450 and AD 1640 and presented a well-healed antemortem penetrating cranial injury on the left parietal bone.

METHODS

Macroscopic and radiographic analyses were conducted and the cranium was also archived digitally with a Faro FreeStyle3D scanner. In addition, well-known literature from neuroscience was synthesized in order to better understand the likely neurological consequences of the injury.

RESULTS

The literature suggests that tasks of attention and working memory, sensory processing, language processing, and vision are affected when the parietal lobe of the brain is injured.

CONCLUSIONS

Burial 195 did not likely return to a 'normal' life after he survived the cranial injury.

SIGNIFICANCE

This study demonstrates that bioarcheological interpretations involving antemortem cranial injuries can be enhanced by collaboration with neuroscientists. Bioarcheological interpretations are improved when the consequences of soft tissue injuries are understood.

LIMITATIONS

This study was limited by a lack of historical documents relevant to the region, time period, and specific case study. In addition, interpretations are cautionary because brain functioning cannot be assessed in vivo in the absence of life.

SUGGESTIONS FOR FURTHER RESEARCH

Bioarcheologists who study antemortem cranial injuries should continue to collaborate with neuroscientists.

Plasticity in language cortex and white matter tracts after resection of dominant inferior parietal lobule arteriovenous malformations: a combined fMRI and DTI study

OBJECTIVE

The dominant inferior parietal lobe (IPL) contains cortical and subcortical structures that serve language processing. A high incidence of postoperative short-term aphasia and good potential for language reorganization have been observed. The authors' goal was to study the plasticity of the language cortex and language-related fibers in patients with brain arteriovenous malformations (BAVMs) located in the IPL.

METHODS

A total of 6 patients who underwent microsurgical treatment of an IPL BAVM were prospectively recruited between September 2016 and May 2018. Blood oxygen level-dependent functional MRI (BOLD-fMRI) and diffusion tensor imaging (DTI) were performed within 1 week before and 6 months after microsurgery. Language-related white matter (WM) eloquent fiber tracts and their contralateral homologous fiber tracts were tracked. The Western Aphasia Battery was administered to assess language function. The authors determined the total number of fibers and mean fractional anisotropy (FA) indices for each individual tract. In addition, they calculated the laterality index (LI) between the activated language cortex voxels in the lesional and contralesional hemispheres and compared these indices between the preoperative and postoperative fMR and DT images.

RESULTS

Of the 6 patients with IPL BAVMs, all experienced postoperative short-term language deficits, and 5 (83.3%) recovered completely at 6 months after surgery. Five patients (83.3%) had right homologous reorganization of BOLD signal activations in both Broca's and Wernicke's areas. More fibers were observed in the arcuate fasciculus (AF) in the lesional hemisphere than in the contralesional hemisphere (1905 vs 254 fibers, p = 0.035). Six months after surgery, a significantly increased number of fibers was seen in the right hemispheric AF (249 fibers preoperatively vs 485 postoperatively, p = 0.026). There were significantly more nerve fibers in the postoperative left inferior frontooccipital fasciculus (IFOF) (874 fibers preoperatively vs 1186 postoperatively, p = 0.010). A statistically significant increase in right hemispheric dominance of Wernicke's area was observed. The overall functional LI showed functional lateralization of Wernicke's area in the right hemisphere (LI ≤ -0.20) in all patients.

CONCLUSIONS

The authors' findings provide evidence for the functional reorganization by recruiting the right hemispheric homologous region of Broca's and Wernicke's areas, right hemispheric AFs, and left hemispheric IFOFs following resection of IPL BAVMs.Clinical trial registration no.: NCT02868008 (clinicaltrials.gov).

Dysfunction of the left angular gyrus may be associated with writing errors in ALS

Background: Language dysfunction is a feature of cognitive impairment in amyotrophic lateral sclerosis (ALS) that may compromise communication. Objective: To elucidate language dysfunction in patients with ALS and its relationship with other neuropsychological tests and to identify the brain regions associated with this dysfunction using perfusion image. Methods: Overall, 37 patients with ALS were included in this study. Their neuropsychological function was investigated using the Western Aphasia Battery (WAB), Frontal Assessment Battery and Behavioral Assessment of the Dysexecutive Syndrome. N-isopropyl-p-[¹²³I] iodoamphetamine single-photon emission computed tomography was used to examine regional cerebral blood flow and its relationship with WAB scores was investigated using multiple regression analyses, controlled for age, sex and years of education. Results: Frequency of language abnormality in ALS was 8.5% for spontaneous speech, 25.7% for auditory verbal comprehension, 8.8% for repetition, 14.7% for naming, 17.6% for reading and 51.4% for writing. The writing error was mainly omission and substitution of kana letters. Executive tests were correlated with naming (r > 0.5, p < 0.001) and reading (r > 0.4, p < 0.01) scores. With respect to the writing sub-test, positive perfusional relationship was only detected in the left angular gyrus. Conclusions: The left angular gyrus is the region associated with the writing errors observed in ALS.

Dementia with Lewy Bodies with Pure Agraphia for Kanji (Japanese Morphograms)

A 70-year-old dextral woman was admitted to a hospital with agraphia for kanji (Japanese morphograms). She had a history of severe constipation, nightmares, and visual hallucinations. Neurological examinations revealed no obvious Parkinson's disease symptoms. She showed poor skills in writing the kanji for looking at picture objects, [e.g., writing the Japanese word "inu" (which means dog) when she saw a drawing of a dog] or dictated words. A reduced striatal uptake of [¹²³I]-2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane (FP-CIT) on single-photon-emission computed tomography and reduced meta-iodobenzylguanidine (MIBG) cardiac uptake on myocardial scintigraphy were detected. The accumulation of amyloid beta in the bilateral cerebral cortices was observed on amyloid-positron emission tomography. We herein report a case of Lewy body dementia with pure agraphia for kanji with underlying Alzheimer's disease pathology.

Asymmetric Bálint's syndrome with multimodal agnosia, bilateral agraphesthesia, and ineffective kinesthetic reading due to subcortical hemorrhage in the left parieto-occipito-temporal area

We report a patient with asymmetric Bálint's syndrome (predominantly right-sided oculomotor apraxia and simultanagnosia and optic ataxia for the right hemispace), and multimodal agnosia (apperceptive visual agnosia and bilateral associative tactile agnosia) with accompanying right hemianopia, bilateral agraphesthesia, hemispatial neglect, global alexia with unavailable kinesthetic reading, and lexical agraphia for kanji (Japanese morphograms), after hemorrhage in the left parieto-occipito-temporal area. The coexistence of tactile agnosia, bilateral agraphesthesia, and ineffective kinesthetic reading suggests that tactile-kinesthetic information can be interrupted because of damage to the fiber connection from the parietal lobe to the occipito-temporal area, leading to these tactually related cognitive impairments.

Dorsal type letter-by-letter reading accompanying alexia with agraphia due to a lesion of the lateral occipital gyri

We report a patient with alexia with agraphia accompanied by letter-by-letter reading after hemorrhage in the left middle and inferior occipital gyri that spared the angular gyrus and the fusiform gyrus. Kanji (Japanese morphograms) and kana (Japanese phonetic writing) reading and writing tests revealed that alexia with agraphia was characterized by kana-predominant alexia and kanji-predominant agraphia. This type of "dorsal" letter-by-letter reading is discernable from conventional ventral type letter-by-letter reading that is observed in pure alexia in that (1) kinesthetic reading is less effective, (2) kana or literal agraphia coexists, and (3) fundamental visual discrimination is nearly normal.

Selective impairment of On-reading (Chinese-style pronunciation) in alexia with agraphia for kanji due to subcortical hemorrhage in the left posterior middle temporal gyrus

We report a patient with alexia with agraphia for kanji after hemorrhage in the left posterior middle temporal gyrus. The results of single-character kanji reading and two-character on- (Chinese-style pronunciation), kun- (native Japanese pronunciation), and Jukujikun (irregular kun-) reading word tests revealed that the patient could not read kanji characters with on-reading but read the characters with kun-reading. We consider that this on-reading alexia was caused by disconnection between the posterior inferior temporal cortex (orthographic lexicon) and the posterior superior temporal gyrus (phonological lexicon), and preserved kun- and Jukujikun-reading was realized by bypassing the orthography-to-phonology route by the semantic route.

A Rare Clinical Antity; Pure Gerstmann Syndrome

Gerstmann syndrome is defined as a tetrad including agraphia, acalculia, finger agnosia, and right-left disorientation. In the case studies presented in the literature, it has been reported that Gerstmann syndrome usually appears as an incomplete tetrad of symptoms or accompanied by cognitive deficits including aphasia, alexia, apraxia and some perceptual disorders. Here, we present of the patient with left angular and supramarginal gyrus infarction affecting the parietal lobe. In addition to the symptoms mentioned above, the patient had alexia and anomic aphasia as well. We discussed the clinic appearance and reviewed the current literature.

Higher Cortical Visual Disorders

PURPOSE OF REVIEW

This article reviews the disorders that result from disruption of extrastriate regions of the cerebral cortex responsible for higher visual processing. For each disorder, a historical perspective is offered and relevant neuroscientific studies are reviewed.

RECENT FINDINGS

Careful analysis of the consequences of lesions that disrupt visual functions such as facial recognition and written language processing has improved understanding of the role of key regions in these networks. In addition, modern imaging techniques have built upon prior lesion studies to further elucidate the functions of these cortical areas. For example, functional MRI (fMRI) has identified and characterized the response properties of ventral regions that contribute to object recognition and dorsal regions that subserve motion perception and visuospatial attention. Newer network-based functional imaging studies have shed light on the mechanisms behind various causes of spontaneous visual hallucinations.

SUMMARY

Understanding the regions and neural networks responsible for higher-order visual function helps the practicing neurologist to diagnose and manage associated disorders of visual processing and to identify and treat responsible underlying disease.

Unbalanced Occlusion Modifies the Pattern of Brain Activity During Execution of a Finger to Thumb Motor Task

In order to assess possible influences of occlusion on motor performance, we studied by functional magnetic resonance imaging (fMRI) the changes in the blood oxygenation level dependent (BOLD) signal induced at brain level by a finger to thumb motor task in a population of subjects characterized by an asymmetric activation of jaw muscles during clenching (malocclusion). In these subjects, appropriate occlusal correction by an oral orthotic (bite) reduced the masticatory asymmetry. The finger to thumb task was performed while the subject's dental arches were touching, in two conditions: (a) with the teeth in direct contact (Bite OFF) and (b) with the bite interposed between the arches (Bite ON). Both conditions required only a very slight activation of masticatory muscles. Maps of the BOLD signal recorded during the movement were contrasted with the resting condition (activation maps). Between conditions comparison of the activation maps (Bite OFF/Bite ON) showed that, in Bite OFF, the BOLD signal was significantly higher in the trigeminal sensorimotor region, the premotor cortex, the cerebellum, the inferior temporal and occipital cortex, the calcarine cortex, the precuneus on both sides, as well as in the right posterior cingulate cortex. These data are consistent with the hypothesis that malocclusion makes movement performance more difficult, leading to a stronger activation of (a) sensorimotor areas not dealing with the control of the involved body part, (b) regions planning the motor sequence, and (c) the cerebellum, which is essential in motor coordination. Moreover, the findings of a higher activation of temporo-occipital cortex and precuneus/cingulus, respectively, suggest that, during malocclusion, the movement occurs with an increased visual imagery activity, and requires a stronger attentive effort.

Voxel-based lesion analysis of brain regions underlying reading and writing

The neural basis of reading and writing has been a source of inquiry as well as controversy in the neuroscience literature. Reading has been associated with both left posterior ventral temporal zones (termed the "visual word form area") as well as more dorsal zones, primarily in left parietal cortex. Writing has also been associated with left parietal cortex, as well as left sensorimotor cortex and prefrontal regions. Typically, the neural basis of reading and writing are examined in separate studies and/or rely on single case studies exhibiting specific deficits. Functional neuroimaging studies of reading and writing typically identify a large number of activated regions but do not necessarily identify the core, critical hubs. Last, due to constraints on the functional imaging environment, many previous studies have been limited to measuring the brain activity associated with single-word reading and writing, rather than sentence-level processing. In the current study, the brain correlates of reading and writing at both the single- and sentence-level were studied in a large sample of 111 individuals with a history of chronic stroke using voxel-based lesion symptom mapping (VLSM). VLSM provides a whole-brain, voxel-by-voxel statistical analysis of the role of distinct regions in a particular behavior by comparing performance of individuals with and without a lesion at every voxel. Rather than comparing individual cases or small groups with particular behavioral dissociations in reading and writing, VLSM allowed us to analyze data from a large, well-characterized sample of stroke patients exhibiting a wide range of reading and writing impairments. The VLSM analyses revealed that reading was associated with a critical left inferior temporo-occipital focus, while writing was primarily associated with the left supramarginal gyrus. Separate VLSM analyses of single-word versus sentence-level reading showed that sentence-level reading was uniquely associated with anterior to mid-portions of the middle and superior temporal gyri. Both single-word and sentence-level writing overlapped to a great extent in the left supramarginal gyrus, but sentence-level writing was associated with additional underlying white matter pathways such as the internal capsule. These findings suggest that critical aspects of reading and writing processes diverge, with reading relying critically on the ventral visual recognition stream and writing relying on a dorsal visuo-spatial-motor stream.

Frontal Phonological Agraphia and Acalculia with Impaired Verbal Short-Term Memory due to Left Inferior Precentral Gyrus Lesion

We report a patient with phonological agraphia (selective impairment of kana [Japanese phonetic writing] nonwords) and acalculia (mental arithmetic difficulties) with impaired verbal short-term memory after a cerebral hemorrhage in the opercular part of the left precentral gyrus (Brodmann area 6) and the adjacent postcentral gyrus. The patient showed phonemic paragraphia in five-character kana nonword writing, minimal acalculia, and reduced digit and letter span. Mental arithmetic normalized after 8 months and agraphia recovered to the normal range at 1 year after onset, in parallel with an improvement of the auditory letter span score from 4 to 6 over a period of 14 months and in the digit span score from 6 to 7 over 24 months. These results suggest a close relationship between the recovery of agraphia and acalculia and the improvement of verbal short-term memory. The present case also suggests that the opercular part of the precentral gyrus constitutes the phonological route in writing that conveys phonological information of syllable sequences, and its damage causes phonological agraphia and acalculia with reduced verbal short-term memory.

Human Brain Mapping of Visual Script Familiarity between Phonological and Logographic Language: 3 T Functional MRI Study

Neurolinguistic circuitry for two different scripts of language, such as phonological scripts (PhonoS) versus logographic scripts (LogoS) (e.g., English versus Chinese, resp.), recruits segregated neural pathways according to orthographic regularity (OrthoR). The purpose of this study was to identify the effect of VSF for cortical representation according to different OrthoR to represent Hangul versus Hanja as PhonoS versus LogoS, respectively. A total of 24 right-handed, native Korean undergraduate students with the first language of PhonoS and the second language of LogoS were divided into high- or low-competent groups for L2 of LogoS. The implicit word reading task was performed using Hanja and Hangul scripts during functional magnetic resonance imaging (fMRI) acquisition. Fluctuations of fMRI BOLD signal demonstrated that the LogoS was associated with the ventral pathway, whereas PhonoS was associated with the dorsal pathway. By interaction analysis, compared with high-competent group, low-competent group showed significantly greater activation for Hanja than for Hangul reading in the right superior parietal lobule area and the left supplementary motor area, which might be due to neural efficiency such as attention and cognition rather than core neurolinguistic neural demand like OrthoR processing.

A Case of Anoxic Brain Injury Presenting with Agraphia of kanji in the Foreground

A 63-year-old woman was hospitalized for rehabilitation from the aftereffects of an anoxic brain injury. In addition to a general cognitive decline, agraphia of kana and kanji was noted at the time of admission, which had advanced to agraphia which is dominant in kanji at the time of hospital discharge. Brain magnetic resonance imaging revealed no stroke lesions, and brain perfusion scintigraphy found a decreased blood flow in the bilateral parietal lobes. We hereby report on this case because case reports on agraphia caused by anoxic brain injury are extremely rare.

Neurological impressions on the organization of language networks in the human brain

BACKGROUND

More than 95% of right-handed individuals, as well as almost 80% of left-handed individuals, have left hemisphere dominance for language. The perisylvian networks of the dominant hemisphere tend to be the most important language systems in human brains, usually connected by bidirectional fibres originated from the superior longitudinal fascicle/arcuate fascicle system and potentially modifiable by learning. Neuroplasticity mechanisms take place to preserve neural functions after brain injuries. Language is dependent on a hierarchical interlinkage of serial and parallel processing areas in distinct brain regions considered to be elementary processing units. Whereas aphasic syndromes typically result from injuries to the dominant hemisphere, the extent of the distribution of language functions seems to be variable for each individual.

METHOD

Review of the literature Results: Several theories try to explain the organization of language networks in the human brain from a point of view that involves either modular or distributed processing or sometimes both. The most important evidence for each approach is discussed under the light of modern theories of organization of neural networks.

CONCLUSIONS

Understanding the connectivity patterns of language networks may provide deeper insights into language functions, supporting evidence-based rehabilitation strategies that focus on the enhancement of language organization for patients with aphasic syndromes.

Ideographic Alexia without Involvement of the Fusiform Gyrus in a Korean Stroke Patient: A Serial Functional Magnetic Resonance Imaging Study

Background

Korean orthography is composed of Hanja (ideograms) and Hangul (phonograms). Based on previous studies, the fusiform gyrus has been associated with ideogram reading. We examine serial functional magnetic resonance imaging (fMRI) images in a patient exhibiting dissociation of Hanja and Hangul reading to identify brain areas associated with Hanja reading.

Case Report

fMRI were taken of a 63-year-old man showing profound Hanja alexia with normal Hangul reading after an acute stroke involving the left frontal and parietal lobes, who later spontaneously recovered his Hanja reading ability. Scans were taken while performing Hanja and Hangul reading tasks on three occasions. As a result, in spite of having profound Hanja alexia, partial activation of the fusiform gyrus was observed on the first fMRI. Serial fMRI scans showed activation of the bilateral middle frontal gyri that increased in parallel with the patient's recovery of Hanja reading.

Conclusions

The frontal lobe, not only fusiform gyrus, may play role in reading Hanja, although more evidence is needed.

Neural substrates of Hanja (Logogram) and Hangul (Phonogram) character readings by functional magnetic resonance imaging

The two basic scripts of the Korean writing system, Hanja (the logography of the traditional Korean character) and Hangul (the more newer Korean alphabet), have been used together since the 14th century. While Hanja character has its own morphemic base, Hangul being purely phonemic without morphemic base. These two, therefore, have substantially different outcomes as a language as well as different neural responses. Based on these linguistic differences between Hanja and Hangul, we have launched two studies; first was to find differences in cortical activation when it is stimulated by Hanja and Hangul reading to support the much discussed dual-route hypothesis of logographic and phonological routes in the brain by fMRI (Experiment 1). The second objective was to evaluate how Hanja and Hangul affect comprehension, therefore, recognition memory, specifically the effects of semantic transparency and morphemic clarity on memory consolidation and then related cortical activations, using functional magnetic resonance imaging (fMRI) (Experiment 2). The first fMRI experiment indicated relatively large areas of the brain are activated by Hanja reading compared to Hangul reading. The second experiment, the recognition memory study, revealed two findings, that is there is only a small difference in recognition memory for semantic transparency, while for the morphemic clarity was much larger between Hanja and Hangul. That is the morphemic clarity has significantly more effect than semantic transparency on recognition memory when studies by fMRI in correlation with behavioral study.

Anatomo-functional study of the temporo-parieto-occipital region: dissection, tractographic and brain mapping evidence from a neurosurgical perspective

The temporo-parieto-occipital (TPO) junction is a complex brain territory heavily involved in several high-level neurological functions, such as language, visuo-spatial recognition, writing, reading, symbol processing, calculation, self-processing, working memory, musical memory, and face and object recognition. Recent studies indicate that this area is covered by a thick network of white matter (WM) connections, which provide efficient and multimodal integration of information between both local and distant cortical nodes. It is important for neurosurgeons to have good knowledge of the three-dimensional subcortical organisation of this highly connected region to minimise post-operative permanent deficits. The aim of this dissection study was to highlight the subcortical functional anatomy from a topographical surgical perspective. Eight human hemispheres (four left, four right) obtained from four human cadavers were dissected according to Klingler's technique. Proceeding latero-medially, the authors describe the anatomical courses of and the relationships between the main pathways crossing the TPO. The results obtained from dissection were first integrated with diffusion tensor imaging reconstructions and subsequently with functional data obtained from three surgical cases, all resection of infiltrating glial tumours using direct electrical mapping in awake patients. The subcortical limits for performing safe lesionectomies within the TPO region are as follows: within the parietal region, the anterior horizontal part of the superior longitudinal fasciculus and, more deeply, the arcuate fasciculus; dorsally, the vertical projective thalamo-cortical fibres. For lesions located within the temporal and occipital lobes, the resection should be tailored according to the orientation of the horizontal associative pathways (the inferior fronto-occipital fascicle, inferior longitudinal fascicle and optic radiation). The relationships between the WM tracts and the ventricle system were also examined. These results indicate that a detailed anatomo-functional awareness of the WM architecture within the TPO area is mandatory when approaching intrinsic brain lesions to optimise surgical results and to minimise post-operative morbidity.

Association of dorsal inferior frontooccipital fasciculus fibers in the deep parietal lobe with both reading and writing processes: a brain mapping study

Alexia and agraphia are disorders common to the left inferior parietal lobule, including the angular and supramarginal gyri. However, it is still unclear how these cortical regions interact with other cortical sites and what the most important white matter tracts are in relation to reading and writing processes. Here, the authors present the case of a patient who underwent an awake craniotomy for a left inferior parietal lobule glioma using direct cortical and subcortical electrostimulation. The use of subcortical stimulation allowed identification of the specific white matter tracts associated with reading and writing. These tracts were found as portions of the dorsal inferior frontooccipital fasciculus (IFOF) fibers in the deep parietal lobe that are responsible for connecting the frontal lobe to the superior parietal lobule. These findings are consistent with previous diffusion tensor imaging tractography and functional MRI studies, which suggest that the IFOF may play a role in the reading and writing processes. This is the first report of transient alexia and agraphia elicited through intraoperative direct subcortical electrostimulation, and the findings support the crucial role of the IFOF in reading and writing.

Thickness-based correlations of cortical areas involved in senses, speech and cognitive processes

AIM: To explore the existence of potential correlations of cortical thickness between different functional brain areas.

METHODS: Our material consisted of 38 formalin-fixated human cerebral hemispheres from twenty males and three females, cadaver donors for students’ education. We selected the following cortical areas at each hemisphere to examine: supramarginal gyrus (S), angular gyrus (A), area of colors recognition (F), area of names recognition (N), area of auditory attention (H), area of place memory (M), cortex of the superior wall of the calcarine sulcus (V1) and cortex of the inferior wall of the calcarine sulcus (V2). We measured the thickness of each cortical area and statistically analyzed our data.

RESULTS: We found a significant difference of the mean value of the V1 (P < 0.05) between right and left hemispheres, as well as very significant correlations (P < 0.001) between the following cortical areas: N and F, A and F, S and F, A and S, A and N, S and N. We also found significant correlations (P < 0.01) between the following areas: S and M, S and H, N and H, as well as between the following areas (P < 0.05): V1 and V2, M and F, M and N, A and H.

CONCLUSION: Our results suggest that there could be a potentially stronger impact for objects placed in the left inferior quarter of the visual field. Our study revealed several thickness-based correlations among different functional cortical areas. Most of them seem to have a more or less rational explanation.

Fiber dissection and diffusion tensor imaging tractography study of the temporoparietal fiber intersection area

BACKGROUND

Lesion studies and recent surgical series report important sequelae when the inferior parietal lobe and posterior temporal lobe are damaged. Millions of axons cross through the white matter underlying these cortical areas; however, little is known about the complex organization of these connections.

OBJECTIVE

To analyze the subcortical anatomy of a specific region within the parietal and temporal lobes where 7 long-distances tracts intersect, ie, the temporoparietal fiber intersection area (TPFIA).

METHODS

Four postmortem human hemispheres were dissected, and 4 healthy hemispheres were analyzed through the use of diffusion tensor imaging--based tractography software. The different tracts that intersect at the posterior temporal and parietal lobes were isolated, and the relations with the surrounding structures were analyzed.

RESULTS

Seven tracts pass through the TPFIA: horizontal portion of the superior longitudinal fasciculus, arcuate fasciculus, middle longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, optic radiations, and tapetum. The TPFIA was located deep to the angular gyrus, posterior portion of the supramarginal gyrus, and posterior portion of the superior, middle, and inferior temporal gyri.

CONCLUSION

The TPFIA is a critical neural crossroad; it is traversed by 7 white matter tracts that connect multiple areas of the ipsilateral and contralateral hemisphere. It is also a vulnerable part of the network in that a lesion within this area will produce multiple disconnections. This is valuable information when a surgical approach through the parieto-temporo-occipital junction is planned. To decrease surgical risks, a detailed diffusion tensor imaging tractography reconstruction of the TPFIA should be performed, and intraoperative electric stimulation should be strongly considered.

White-matter microstructure and language lateralization in left-handers: a whole-brain MRI analysis

Most people are left-hemisphere dominant for language. However the neuroanatomy of language lateralization is not fully understood. By combining functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI), we studied whether language lateralization is associated with cerebral white-matter (WM) microstructure. Sixteen healthy, left-handed women aged 20-25 were included in the study. Left-handers were targeted in order to increase the chances of involving subjects with atypical language lateralization. Language lateralization was determined by fMRI using a verbal fluency paradigm. Tract-based spatial statistics analysis of DTI data was applied to test for WM microstructural correlates of language lateralization across the whole brain. Fractional anisotropy and mean diffusivity were used as indicators of WM microstructural organization. Right-hemispheric language dominance was associated with reduced microstructural integrity of the left superior longitudinal fasciculus and left-sided parietal lobe WM. In left-handed women, reduced integrity of the left-sided language related tracts may be closely linked to the development of right hemispheric language dominance. Our results may offer new insights into language lateralization and structure-function relationships in human language system.

Inter- and intrahemispheric connectivity differences when reading Japanese Kanji and Hiragana

Unlike most languages that are written using a single script, Japanese uses multiple scripts including morphographic Kanji and syllabographic Hiragana and Katakana. Here, we used functional magnetic resonance imaging with dynamic causal modeling to investigate competing theories regarding the neural processing of Kanji and Hiragana during a visual lexical decision task. First, a bilateral model investigated interhemispheric connectivity between ventral occipito–temporal (vOT) cortex and Broca's area (“pars opercularis”). We found that Kanji significantly increased the connection strength from right-to-left vOT. This is interpreted in terms of increased right vOT activity for visually complex Kanji being integrated into the left (i.e. language dominant) hemisphere. Secondly, we used a unilateral left hemisphere model to test whether Kanji and Hiragana rely preferentially on ventral and dorsal paths, respectively, that is, they have different intrahemispheric functional connectivity profiles. Consistent with this hypothesis, we found that Kanji increased connectivity within the ventral path (V1 ↔ vOT ↔ Broca's area), and that Hiragana increased connectivity within the dorsal path (V1 ↔ supramarginal gyrus ↔ Broca's area). Overall, the results illustrate how the differential processing demands of Kanji and Hiragana influence both inter- and intrahemispheric interactions.

Neural network development in late adolescents during observation of risk-taking action

Emotional maturity and social awareness are important for adolescents, particularly college students beginning to face the challenges and risks of the adult world. However, there has been relatively little research into personality maturation and psychological development during late adolescence and the neural changes underlying this development. We investigated the correlation between psychological properties (neuroticism, extraversion, anxiety, and depression) and age among late adolescents (n = 25, from 18 years and 1 month to 22 years and 8 months). The results revealed that late adolescents became less neurotic, less anxious, less depressive and more extraverted as they aged. Participants then observed video clips depicting hand movements with and without a risk of harm (risk-taking or safe actions) during functional magnetic resonance imaging (fMRI). The results revealed that risk-taking actions elicited significantly stronger activation in the bilateral inferior parietal lobule, temporal visual regions (superior/middle temporal areas), and parieto-occipital visual areas (cuneus, middle occipital gyri, precuneus). We found positive correlations of age and extraversion with neural activation in the insula, middle temporal gyrus, lingual gyrus, and precuneus. We also found a negative correlation of age and anxiety with activation in the angular gyrus, precentral gyrus, and red nucleus/substantia nigra. Moreover, we found that insula activation mediated the relationship between age and extraversion. Overall, our results indicate that late adolescents become less anxious and more extraverted with age, a process involving functional neural changes in brain networks related to social cognition and emotional processing. The possible neural mechanisms of psychological and social maturation during late adolescence are discussed.

Thalamic alexia with agraphia

Alexia with agraphia is defined as an acquired impairment affecting reading and writing ability. It can be associated with aphasia, but can also occur as an isolated entity. This impairment has classically been associated with a left angular gyrus lesion In the present study, we describe a case involving a patient who developed alexia with agraphia and other cognitive deficits after a thalamic hemorrhage. In addition, we discuss potential mechanisms of this cortical dysfunction syndrome caused by subcortical injury. We examined a patient who presented with alexia with agraphia and other cognitive deficits due to a hemorrhage in the left thalamus. Neuropsychological evaluation showed attention, executive function, arithmetic and memory impairments. In addition, language tests revealed severe alexia with agraphia in the absence of aphasia. Imaging studies disclosed an old thalamic hemorrhage involving the anterior, dorsomedial and pulvinar nuclei. Tractography revealed asymmetric thalamocortical radiations in the parietal region (left Collapse

Key Words

• agraphia with alexia
• diaschisis phenomenon
• thalamic lesion
• tract disconnection.

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Affiliation(s)

Fábio Henrique de Gobbi Porto Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)
Maria Isabel d'Ávila Freitas Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)
Maira Okada de Oliveira Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)
Leandro Tavares Lucato Department of Radiology, Clinical Hospital of University of São Paulo, São Paulo
Marco Orsini Neurology Department, Fluminense Federal University and Masters Program in Science Rehabilitation, UNISUAM, Rio de Janeiro
Sara Lúcia Silveira de Menezes Masters Program in Science Rehabilitation, UNISUAM, Rio de Janeiro
Regina Miksian Magaldi Memory and Aging Unit, Geriatric Service, Department of Clinical Medicine and Cognitive Disorders Reference Center, University of São Paulo School of Medicine, São Paulo SP, Brazil
Cláudia Sellitto Porto Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)
Sonia Maria Dozzi Brucki Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)
Ricardo Nitrini Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)

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[Lesion localization of non-aphasic alexia and agraphia]

The author reviews the lesion localization of non-aphasic alexia and agraphia and proposes a new classification of alexia and agraphia on this basis. The newly proposed alexia and agraphia are pure alexia for kana (Japanese phonograms), or more generally pure alexia for letters, caused by a lesion in the posterior occipital area (posterior fusiform/inferior occipital gyri), and pure agraphia for kanji (Japanese morphograms) caused by a lesion in the posterior middle temporal gyrus and also a lesion restricted to the angular gyrus. In addition, the anatomical lesions presumably responsible for the parietal apraxic agraphia, frontal pure agraphia and thalamic agraphia are discussed.