Neurocase The Neural Basis of Cognition ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/nncs20 Visual texture agnosia caused by bilateral posterior cerebral artery stroke: a case study Mamiko Sato, Yasutaka Kobayashi & Masahito Hitosugi To cite this article: Mamiko Sato, Yasutaka Kobayashi & Masahito Hitosugi (2021): Visual texture agnosia caused by bilateral posterior cerebral artery stroke: a case study, Neurocase, DOI: 10.1080/13554794.2021.1909068 To link to this article: https://doi.org/10.1080/13554794.2021.1909068 Published online: 14 Apr 2021. Submit your article to this journal Article views: 21 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=nncs20 NEUROCASE https://doi.org/10.1080/13554794.2021.1909068 Visual texture agnosia caused by bilateral posterior cerebral artery stroke: a case study Mamiko Satoa, Yasutaka Kobayashib and Masahito Hitosugic a Department of Rehabilitation Medicine, Fukui General Hospital, Fukui, Japan; bGraduate School of Health Science, Fukui Health Science University, Fukui, Japan; cDivision of Legal Medicine, Shiga University of Medical Science, Shiga, Japan ABSTRACT ARTICLE HISTORY A 57-year-old man presented with a bilateral posterior cerebral artery attack and was visually impaired. He had a hard time identifying familiar faces and shades. He also felt that the familiar building looked different, and complained that it was not possible to tell from visual information alone whether the food was cooked or the kimono fabric was soft.We assessed the patient’s visual function using real materials and material images and was diagnosed with visual texture agnosia. There are few reports of visual texture agnosia, detailed evaluation is considered important because perceiving texture is important for activities of daily living. Received 15 October 2020 Accepted 23 March 2021 Introduction For visual object recognition, not only form and color but also surface characteristics, such as texture, are equally important. It has become clear in recent years that form, color, and texture are often discussed separately because it is now known that each neural pathway is independent of the other. The texture of an object is important for identifying an object and knowing its state; therefore, texture analysis is important for daily func­ tions. For example, determining whether the material of an object is wood or metal, whether the ground is wet or dry, whether food is still fresh, and whether meat products are completely cooked requires the individual to distinguish between textures. Textures are understood based on multiple sensory modalities, such as tactile sense, visual sense, and auditory sense. Textures detected by each sensory modality are integrated by learning so that the textures can be inferred based on visual information only. A state in which textures can be recognized by information, such as hearing and touch, but cannot be recognized only by the visual information is called visual texture agnosia. We report a case of bilateral posterior cerebral artery infarction that caused impairment of color and texture perception despite preservation of form perception. Materials and methods A 57-year-old male patient was brought to Hospital A on 1 September 2018, due to experiencing a disturbance in con­ sciousness at work. The patient was diagnosed with bilateral posterior cerebral artery stroke and admitted on the same day. His past medical history included surgery for bladder cancer in 1994 and untreated hyperlipidemia, hyperuricemia, and dia­ betes since around 2013. Approximately 2 years earlier, the patient began experiencing occasional severe headaches with the subjective symptom of blurred vision, and he began taking CONTACT Mamiko Sato satomoko@f-gh.jp KEYWORDS Visual texture agnosia; bilateral posterior cerebral artery; reversible cerebral vasoconstriction syndrome; texton; real materials; material images analgesics. The patient had no family history of note. His occu­ pation was the manager of a kimono store. Diffusion-weighted imaging (DWI) of head magnetic resonance imaging performed at the time of onset indicated a high-intensity region corre­ sponding to the bilateral posterior cerebral artery region (Figure 1(a)). Moreover, magnetic resonance angiography (MRA) showed narrowing of the bilateral posterior cerebral arteries, wall irregularity, and poor visualization of the distal region (P3 segment and beyond; Figure 1(b)). On day 7 of the patient’s hospital stay, the bilateral posterior cerebral arteries were well visualized to the periphery using MRA (Figure 1(c)). Based on the above course and the patient’s history of head­ ache, cerebral infarction was thought to be caused by reversi­ ble cerebral vasoconstriction syndrome (RCVS). Consciousness disturbance was abolished following conservative treatment, and the patient had no paralysis of the limbs or trunk. However, due to the patient’s visual impairment, he required assistance to move about. He was transferred to our hospital for rehabili­ tation on hospital day 25. On admission, the patient had a height of 188 cm, a bodyweight of 76 kg, blood pressure of 114/77 mmHg, and heart rate of 66/min. There were no general physical findings. The patient was alert and did not have aphasia or apraxia. He complained of visual impairment; the visual acuity in the patient’s right and left eye were 20/500 and 20/333, respec­ tively. The visual field was maintained in the lower right quad­ rant of both eyes. The percentage of correct answers in the color vision test was low at 49%. His chief complaint was that all his vision looked sepia. He could not understand the cooking condition of food, the texture of the kimono, the warmth of wood, and the skin color and luster of others. Thus, all the faces of others looked like mannequins. However, except for visual disorders; cranial neuropathy, limb/trunk movement disorder, limb/trunk sensory disorder, Department of Rehabilitation, Fukui General Hospital, Egami Town, Fikui, Fukui 58-16-1, Japan © 2021 Informa UK Limited, trading as Taylor & Francis Group 2 M. SATO ET AL. distinguishing between black-navy blue and orange-red hues. No abnormalities were noted regarding symbol recognition. In visual space recognition and operation, there was an oversight regarding the upper side in the line cancellation and number reading. Concerning topographical orientation, the patient did not understand the layout of his house or the hospital and described familiar places in the hospital as if they were seen for the first time every single time. Visual impairment, visual field impairment, color blindness, memory impairment, atten­ tion disorder, facial agnosia, and landmark agnosia were noted based on neurological findings and neuropsychological test results. Moreover, since abnormalities in texture perception were suspected based on subjective symptoms related to visual perception, the following additional tests were performed. Evaluation of texture recognition Figure 1. Head magnetic resonance imaging and magnetic resonance angiogra­ phy (MRA) at onset and on hospital day 7 (a) Diffusion-weighted imaging (DWI) performed at the time of onset shows a bilateral posterior cerebral artery infarc­ tion. (b) MRA performed at the time of onset showed stenosis and wall irregu­ larity in the bilateral posterior cerebral artery region and poor visualization of blood vessels from P3. (c) MRA performed on hospital day 7 revealed that the bilateral posterior cerebral artery stenosis and wall irregularity had disappeared, and blood vessels were well visualized to the periphery. ataxia, deep tendon reflex abnormality, and autonomic neuro­ pathy were not observed. The scores for the neuropsychological tests were as follows. The cutoff values for each test are shown in parentheses. In the evaluations done using the Wechsler Adult Intelligence Scale-III (Fujita et al., 2007), verbal IQ score was 102, behavioral IQ 120, full-scale IQ 79, verbal comprehension 107, perceptual organi­ zation 91, working memory 135, processing speed 78 (85 each). Using the Wechsler Memory Scale-Revised (Sugishita, 2007), verbal memory 86, visual memory 86, general memory 84, attention/concentration 87, delayed memory 86 (85 each). Using the the Rivermead Behavioral Memory Test (Watamori et al., 2002) standardized profile 19 (16), screening 8 (7). Using the Clinical Assessment for Attention (Japan Society for Higher Brain Dysfunction, 2008, the time periods required for the visual cancellation task was 120 s (71), and for the Position Stroop Test was 94 s (76). The achievement rate of the symbol digit mod­ alities test was 17.3% (50.9%), and the correct response rate of the Position Stroop Test was below 96% (99.2%). The results for the visual perception test for agnosia (Japan Society for Higher Brain Dysfunction, 2006) were as follows: Concerning basic visual perception, the patient claimed that the scenery looked like a black and white painting and did not appear realistic. Also, the patient required time to visually identify the numbers. In object/image recognition, the patient had trouble under­ standing context picture and could classify pictures; however, the classification process took time. Regarding face recognition, the patient made errors in recognizing familiar faces. In per­ forming color recognition, the patient had difficulty Identification of texton: The evaluation was performed by using textons proposed by Julesz (Julesz, 1981). As an ele­ mental evaluation of the texture, the task of finding one texton difference was performed to recognize the qualitative difference of the texton (Figure 2(a)). Next, the possibility to discriminate whether the size of the region formed by the difference in the texton was the same or different was eval­ uated (Figure 2(b)). Furthermore, as a control task, whether the difference in the size of the region due to the difference in color could be discriminated was also evaluated (Figure 2(c)). These evaluations were performed 20 times each in the patient and five age-matched healthy subjects. The correct response rate and mean reaction time were calculated. The correct response rate was 100% by all patients in all the tasks, but the mean time from task presentation to response was longer than the five healthy subjects (Table 1). All reaction times for each evaluation task were plotted and compared with the data of cases and five healthy subjects in a graph. In addition, 95% confidence intervals were inserted for each task (Figure 3). Identification of real materials Texture recognition was evaluated based on whether or not the material could be identified. It is known that the neural path­ ways for discriminating and identifying the real material and the image material are different from each other. Therefore, the real material and the image material were identified and eval­ uated. Just as Suzuki conducted an inspection to identify mate­ rials using nine real materials (Suzuki, 2015), this study also identified real materials in the same way. Nine different types of materials (i.e. wood, metal, glass, pottery, fur, leather, stone, bark, and cloth) were partially presented through a 60 mm × 20 mm hole to block information regarding the shape of the objects. The tasks were performed five times for each material. The mean correct response rate was 40%, which was lower than the correct response rate of 81% among five age-matched healthy subjects, and the decrease in the correct response rate was remarkable, especially regarding metal, glass, fur, leather, bark, and cloth (Table 2). NEUROCASE 3 Figure 2. Identification of texton. (a) The task to search for one texton. (b) The task to discriminate the size of the area by texton. (c) The task to discriminate the size of the area based on the difference in color. Table 1. Identification of texton. a. Search for one texton b. Determination of area by texton c. Determination of areas by color Correct response rate (%) Mean reaction time (seconds) Correct response rate (%) Mean reaction time (seconds) Correct response rate (%) Mean reaction time (seconds) Identification of material images Using images (90 mm × 60 mm) of the same nine types of material, the task of asking whether two material images of random combi­ nation are of the same or different materials (as a discrimination task) and the task of identifying the material of the material image Patient 100 1.55 100 2.03 100 1.65 Healthy controls 100 0.79 ± 0.16 100 1.34 ± 0.20 98 1.04 ± 0.19 (as an identification task) were evaluated. Each task was performed 20 times. The correct response rate of the patient was 75% for discrimination and 25% for identification, which was lower than the correct response rate of five age-matched healthy subjects (93% and 99%, respectively). The mean time from task presenta­ tion to response was longer than five age-matched healthy Figure 3. Reaction times for tasks using texton. (a) The task to search for one texton. (b) The task to determine area by texton. (c) The task to determine area by color. 4 M. SATO ET AL. Table 2. Identification of real materials. Examples of incorrect response Wood Paper Patients’ correct response rate Healthy controls’ correct response rate 60% 96% Metal Mirror Plastic 20% 80% Glass Aluminum Iron 40% 84% Pottery Paper Fur Cloth Leather Plastic 80% 84% 20% 96% 40% 52% Stone Pottery Cotton 60% 100% Bark Paper Kelp 0% 56% Cloth Paper Wood 40% 84% Mean 40% 81% Table 3. Identification of material images. a. Discrimination of materials b. Identification of materials Correct response rate (%) Mean reaction time (seconds) Correct response rate (%) Mean reaction time (seconds) controls (Table 3.). All the reaction times for each evaluation task were plotted and the data was compared for cases and five healthy subjects on a graph. In addition, 95% confidence intervals was inserted for each (Figure 4). Visual texture agnosia was diagnosed in the patient based on the results of the aforementioned examinations. Following hospital transfer, the patient’s vision gradually improved. On hospital day 40, he could move independently within the ward. On hospital day 60, oculomotor trainings and visual cognitive training using a computer and screen were initiated. On hospital day 90, the patient’s prosopagnosia and memory dis­ order had mostly disappeared, and he was discharged. However, the patient’s visual field disorder, blue–orange dis­ crimination disorder, visual texture agnosia, and landmark agnosia persisted. These symptoms, as well as the patient’s discomfort because familiar buildings near his house looked similar, prompted the decision to give him a navigation map. The patient could subsequently go outdoors and returned to work after 120 days. Discussion The present case was characterized by bilateral posterior cere­ bral artery stroke associated with RCVS, which caused visual cognitive dysfunction, visual field and color blindness, visual texture agnosia, prosopagnosia, and scene agnosia. Patient 75 2.5 25 3.15 Healthy controls 93 1.59 ± 0.57 99 1.44 ± 0.59 Visual information first reaches the primary visual cortex on the medial side of the occipital lobe from the retina, and enters via dorsal and ventral streams (Goodale & Milner, 1992). In particular, the ventral stream is a route for recog­ nizing an object based on shape, color, and texture. When the ventral stream is impaired, the following conditions may develop: visual agnosia, in which an object cannot be identi­ fied based on the shape (Lissauer, 1890); color blindness, in which the color cannot be determined (Tranel, 2001); and visual texture agnosia, in which the material cannot be iden­ tified from the texture (Suzuki, 2015). Furthermore, it has been suggested that shape, color, and texture do not inter­ fere with each other and are processed by different neural pathways (Cant et al., 2008); however, these pathways work complementarily during the visual recognition of an object. Recent studies using neuroimaging methods have shown that the relevant active parts slightly differ depending on which visual characteristic of the object is focused upon. For example, it has been demonstrated that the lateral sur­ face of the occipital lobe is activated when focusing on geometric features and the medial surface of the occipital lobe is activated when focusing on surface features (Cant & Goodale, 2007). Visual target recognition is analyzed using shape, color, and texture. The responsible lesions are related to the lateral occipital region for shapes, the lingual gyrus to collateral fissure region for color, and the posterior region of the collateral fissure for texture (Cavina-Pratesi et al., 2010a). Figure 4. Reaction time for evaluation tasks. (a) The task to discriminate material images. (b) The task to identify material images. NEUROCASE Poor visual texture recognition has been clinically reported in patients with lesions of the occipitotemporal cortex caused by cerebral infarction, traumatic brain injury, encephalitis, or other pathological conditions (Cavina-Pratesi et al., 2010a; Suzuki, 2015; Suzuki et al., 2000; Suzuki & Uno, 2012; Vaina, 1990). Texture agnosia has not received much clinical attention so far. However, reporting cases of texture agnosia will be important now that the neural basis of texture has begun to be elucidated. Furthermore, studies in recent years on visual agnosia of dementia with visual cognitive impairment, such as Lewy body dementias and Alzheimer’s disease, have been reported (Oishi et al., 2018, 2020). The present case had a widespread lesion in the bilateral occipital and temporal lobes including the bilateral collateral fissure, fusiform gyrus, lingual gyrus, and the parahippocampal gyrus. Similar to Cavina-Pratesi’s case and Suzuki’s case A, shape perception was retained and color and texture percep­ tion were impaired (Cavina-Pratesi et al., 2010b; Suzuki, 2015). However, Vaina’s case report showed that only the recognition of shape and texture were impaired (Vaina, 1990). Also, in Suzuki’s case B, only the recognition of texture was impaired (Suzuki, 2015). Thus, it is important to separately evaluate shape, color, and texture to further elucidate neural pathways based on visual characteristics. Past reports have indicated a strong correlation with the left medial temporal lobe cen­ tered on the collateral fissure and suggest that symptoms may be manifested by the additional presence of a lesion in the right occipital lobe or lateral temporal lobe. Previous reports have pointed out that the left collateral groove may play a more important role. However, previous functional MRI studies have pointed out the involvement of bilateral collateral grooves in texture recognition (Cant & Goodale, 2011) . Furthermore, Suzuki reported a case in which the real texture cognition was not impaired but only the image texture cognitive impairment was exhibited and inferred that the addition of the lesion in the right occipital lobe to the lesion in the left medial occipital lobe would make the symptoms more apparent. When recognizing an image object, that is, a two-dimensional object, the texture recognition of the two-dimensional object is more advanced because other clues of the three-dimensional object, such as depth cannot be used. Moreover, the function of reconstruct­ ing the two-dimensional object to the third dimension is also required. Thus, if a problem with visual perception even if no complaint about the texture of the real object exists, texture scrutiny is required to pick up potential texture agnosia, tex­ tures, images, and all of the real thing. In cases with problems with visual cognition, it is important to evaluate the texture reliably and accumulate cases showing similar findings. Thus, evaluation and accumulation/collection of data regarding such cases is important. Research in the field of texture brain informatics is proceed­ ing. Although detailed neural pathways related to visual cogni­ tion have been clarified by studies using functional neuroimaging, case reports of visual texture agnosia are rare. It is likely that when the symptoms are mild, they are difficult to notice because they do not interfere with the activities of daily living. Conversely, in severe cases, assessment is difficult due to the complications of visual and sensory impairment. Standard 5 visual perception assessments do not include items related to texture perception, and visual texture agnosia is likely to be overlooked. In this case, always being aware of the texture of the kimono at work is important because the patient was highly sensitive to the texture even before the onset of the stroke. A detailed introspection-based appeal of his eyesight during rehabilitation led to the diagnosis. The texture is an important source of information in everyday life, and visual texture agno­ sia may interfere with social life, but it is often difficult to notice the symptoms. Therefore, evaluation for texture agnosia should be performed in cases with visual perception impairment. Connecting it with rehabilitation, such as making patients aware of using other sensory modalities is necessary if abnorm­ alities are found in the evaluation. Disclosure of interest No potential competing interest was reported by the authors. References Cant, J. S., & Goodale, M. A. (2007). 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