Selective impairment in musical chord Reading in posterior cortical atrophy: A case study of integrative visual agnosia

Abstract

Background

Posterior cortical atrophy (PCA) is a rare neurodegenerative disorder characterized by visuospatial and/or visuoperceptual deficits, resulting from atrophy in the occipitoparietal and/or occipitotemporal cortices. Among reported cases, visuoperceptual deficits are less commonly described compared to visuospatial impairments.

Objective

To address this gap, we present a qualitative behavioral observation of an individual with PCA in which visuoperceptual deficits manifested as symbolically intuitive symptoms.

Methods

This case study examines a 58-year-old female with PCA whose primary symptom was difficulty reading chords on musical scores, despite being able to perceive their overall shape and having no difficulty reading individual notes or other musical symbols such as flats (♭) and sharps (♯). Her challenges are discussed within the framework of integrative visual agnosia, a condition involving the inability to synthesize partial visual inputs into cohesive wholes. A comprehensive neuropsychological evaluation was performed, and brain imaging—including positron emission tomography (PET)—was used to explore underlying pathology.

Results

Neuropsychological testing revealed severe alexia, characterized by word-by-word reading, and visual object agnosia with minimal visuospatial deficits. These visuoperceptual impairments were marked by fragmented perception of objects and failure to integrate parts as object complexity increased. Imaging showed left-dominant occipitotemporal abnormalities consistent with Alzheimer's disease pathology, confirmed by amyloid-β and tau PET findings.

Conclusions

This case highlights the diagnostic challenges clinicians face in recognizing visuoperceptual deficits in PCA. The individual's integrative visual agnosia, exemplified by her difficulty interpreting musical chords, offers valuable insight into how such deficits manifest in daily activities.

Keywords

Alzheimer's disease integrative visual agnosia musical chord positron emission tomography posterior cortical atrophy visual complexity visuoperceptual deficit

Introduction

Posterior cortical atrophy (PCA) is a rare neurodegenerative dementia primarily characterized by progressive visuospatial and/or visuoperceptual dysfunction.^1–3 Unlike typical Alzheimer's disease, which commonly presents with memory or language impairments, PCA predominantly manifests with visual processing deficits that interfere with daily activities.⁴ However, because such deficits are less readily recognized than memory or language impairments, they are often overlooked, leading to diagnostic delays.⁵ The initial presentation is typically dominated by visual complaints without prominent early memory, language, or behavioral disturbances, which may further obscure recognition. Although no disease-specific curative therapy exists for PCA, early and accurate diagnosis remains clinically important. Timely recognition helps prevent misattribution of symptoms to primary ophthalmological or psychiatric conditions, allows appropriate symptomatic management of underlying Alzheimer's disease pathology, and facilitates early implementation of safety measures and caregiver support.⁶

Beyond its clinical heterogeneity, PCA also raises important theoretical questions regarding the neural mechanisms of perceptual integration and hierarchical visual processing.⁶ Understanding how complex visual stimuli are disrupted in PCA may therefore contribute not only to improved diagnosis but also to broader models of visual cognition in neurodegenerative disease.⁷

The biparietal variant of PCA is well-documented, with numerous case reports describing hallmark visuospatial deficits.^8,9 These reports have described difficulties such as dressing apraxia and left/right disorientation and have particularly focused on Balint's syndrome—a characteristic constellation of dorsal visual impairments. Key features of Balint's syndrome—dorsal simultanagnosia, the inability to perceive multiple objects simultaneously; optic ataxia, the inability to use vision to accurately guide hand movements when reaching for objects; and oculomotor apraxia, the inability to voluntarily shift gaze to the object of interest despite intact extraocular muscle function—are relatively straightforward to detect and provide clear diagnostic clues.¹⁰

In contrast, the occipitotemporal variant of PCA, which primarily involves the ventral visual pathway atrophy and is characterized by visuoperceptual dysfunction, has been less frequently described in detailed clinical observations.^11–13 Despite evidence from a 2024 meta-analysis indicating that up to 42% of PCA patients present with object perception deficits,¹⁴ the prevalence of such symptoms in clinical reports remains disproportionately low. This discrepancy may stem not only from the subtle nature of visuoperceptual deficits—which are frequently misattributed to ophthalmological conditions—but also from the structure of routine cognitive assessments. Standard dementia screening tools, such as the Mini-Mental State Examination, place greater emphasis on memory and language functions and may lack sensitivity to higher-order visuoperceptual disturbances. As a result, ventral-stream deficits characteristic of occipitotemporal PCA may remain under-recognized in typical clinical evaluations.¹⁵ Among the limited reports on the occipitotemporal variant of PCA, Shiio et al. provided a detailed discussion of visuoperceptual impairments.¹³ However, their primary focus was on the pathomechanism of the ventral variant of PCA, and the reported symptomatology included a combination of visual agnosia, such as apperceptive visual agnosia: the inability to copy objects, or ventral simultanagnosia, described by Farah as a failure to integrate multiple visual objects into a coherent whole despite intact perception of individual components.¹⁶ Additionally, their case included visuospatial impairments, such as hemispatial neglect, adding further complexity to the clinical presentation. The heterogeneity of these visual impairments poses significant challenges in accurately depicting a patient's visual experience and in understanding the specific mechanisms underlying their functional limitations.

To bridge the knowledge gap, we present a detailed case study of an individual with occipitotemporal PCA. Her unique visuoperceptual deficit—an inability to read musical chords despite intact abilities to perceive overall shapes and read individual notes and symbols—illustrates integrative visual agnosia, a condition marked by impaired synthesis of visual components into a cohesive whole. From a theoretical perspective, this type of deficit is particularly informative. Musical notation engages complex visuomotor and perceptual processes,¹⁷ and can be conceptualized as a form of hierarchical visual processing. A musical chord consists of multiple notes arranged vertically within a shared spatial frame (the five-line staff) and must be perceived as a unified harmonic structure rather than as independent elements. Efficient chord recognition therefore requires rapid part–whole integration and sensitivity to spatial configuration, processes closely aligned with theories of visual Gestalt organization and hierarchical perceptual encoding.^18,19 The present case thus offers a naturalistic illustration of impaired hierarchical visual integration in occipitotemporal PCA. This observation also raises an important diagnostic question regarding how such integration failures should be conceptualized within existing models of visual agnosia. Although integrative visual agnosia and ventral simultanagnosia share overlapping features, this case allows us to examine in detail how her impairment may be more appropriately understood in terms of the former. While these characteristics may not encompass all aspects of visuoperceptual deficits in PCA, they provide valuable insights into one of its core features.

Methods

Case presentation

The individual was a 58-year-old right-handed woman with a 12-year education. She had no history of physical, neurological, or psychological conditions. Her father had developed Alzheimer's disease in his eighties. She received approximately 10 years of formal piano instruction during childhood and adolescence and had continued playing the electronic organ recreationally for over 38 years. She was familiar with basic music theory, including chord structures and harmonic progressions, and was accustomed to reading multi-note chord notations fluently prior to symptom onset. She reported that chord recognition had been automatic and visually immediate, rather than relying on conscious theoretical calculation of interval structures.

She had worked for approximately 20 years in the accounting and payroll department of an eyewear retail company, a position involving sustained visual attention to densely printed numerical and textual documents, including payroll and insurance records. At age 55, she began experiencing frequent eye fatigue while reviewing such documents, which eventually led her to leave her job. By age 56, she reported difficulty reading musical chords, describing them as “jumbled up.” Despite this, she could perceive their overall shape and accurately identify individual notes, including pitch, length, flats (♭), and sharps (♯). Initial ophthalmological evaluations revealed no abnormalities. However, by age 57, she could no longer read television subtitles or on-screen scrolling text and experienced nausea while reading books. A second ophthalmologist identified signs of central nervous system dysfunction and referred her for a neurological evaluation.

Neurological findings

Neurological examination showed no cranial nerve, motor, or sensory deficits. Extrapyramidal symptoms were absent. She exhibited object agnosia, as evidenced by her inability to immediately recognize a key attached to a key ring. However, upon touching it, she correctly identified the object, suggesting modality-specific agnosia. She reported no difficulties consistent with color agnosia, prosopagnosia, or texture agnosia—the latter being defined as the inability to recognize material textures based on their three-dimensional shape or reflective surface properties.²⁰ She exhibited no visual field defects during confrontation testing and reported no significant visuospatial impairments, as she retained the ability to navigate, grasp objects, and avoid obstacles or people, even in crowded environments. Ophthalmologic examination demonstrated normal corrected visual acuity of 20/40 in the right eye and 20/20 in the left eye, with no abnormalities in the ocular fundus, cataracts, or glaucoma. In addition, her reported difficulty in reading musical chords was explored during the clinical evaluation using her own musical scores. She was asked to read familiar pieces and describe what she perceived. She was able to name individual notes accurately but failed to recognize multi-note chords, reporting that the configuration did not appear as a unified whole and instead seemed visually disorganized. This observation was documented qualitatively during routine clinical assessment; no formal experimental or quantitative testing of musical processing was performed.

Imaging studies

Neuroimaging was performed as part of routine clinical evaluation. Structural magnetic resonance imaging (MRI) was conducted shortly after the initial presentation using a 3.0-T scanner, including T1-weighted sequences acquired in axial and coronal planes. Brain perfusion single-photon emission computed tomography (SPECT) was performed using 99mTc-ethyl cysteinate dimer (99mTc-ECD). SPECT data were analyzed with an easy Z-score imaging system (e-ZIS) to assess regional cerebral blood flow relative to an age-matched normative database.²¹ Amyloid positron emission tomography (PET) using ¹¹C-PiB and tau PET using ¹⁸F-florzolotau were performed approximately 18 months after the initial visit to further characterize underlying Alzheimer's disease pathology. PET images were interpreted by experienced nuclear medicine physicians using standard clinical criteria.

Neuropsychological assessment

Neuropsychological functioning was assessed using standardized cognitive tests to evaluate general cognitive abilities, including memory, attention, intelligence, language, and, specifically, visual cognition. All assessments were conducted by one of the co-authors, FS, an experienced neuropsychologist with over 30 years of expertise, in an outpatient setting over a four-month period following the initial visit.

Given the descriptive nature of this single-case analysis and the limited availability of standardized normative data for some subtests, criteria for impairment were based on available reference distributions or manual norms rather than uniform z-scores.

Basic cognitive and intellectual functioning

Three tests were administered to evaluate the individual's basic cognitive and intellectual functions, as outlined below:

Mini-Mental State Examination, Japanese Version (MMSE-J)²²: Used to assess the individual's basic cognitive functioning.

COGNISTAT, Japanese Edition²³: This test evaluates general cognitive abilities, incorporating tasks such as line-drawing object naming and situational description which help assessing visual processing.

Wechsler Adult Intelligence Scale—Fourth Edition, Japanese Edition (WAIS-IV)²⁴: Employed to provide a comprehensive assessment of general intellectual functioning, focusing on four specific domains: verbal comprehension, perceptual organization, working memory, and processing speed.

Language functioning

Language functioning was assessed using the following test:

Standard Language Test of Aphasia (SLTA)²⁵: A validated and standardized test developed in Japan to evaluate multiple aspects of aphasia. The SLTA comprises 26 subtests measuring abilities in listening, speaking, reading, writing, and calculation on a six-point scale. It was specifically employed to assess language impairments, such as alexia and agraphia. The reading and writing subtests evaluate difficulties in processing hiragana and kanji, two essential components of the Japanese writing system. Kanji are complex logographic characters of Chinese origin, while hiragana is a simpler phonetic script resembling an alphabet, with characters typically composed of one to four strokes.

Visuoperceptual functioning

Three tests were employed to assess the individual's visuoperceptual abilities. These tests focused on evaluating basic visuoperceptual function, the cognitive challenges posed by complex and dense visual information, and visual processing biases at both local and global levels.

Visual Perception Test for Agnosia (VPTA)²⁶: A validated and standardized test developed in Japan to evaluate visuoperceptual and visuospatial functioning. Subtests assess basic visual abilities such as line-length discrimination, shape recognition, slope detection, figure copying, and dot counting, as well as higher-order functions, such as recognizing images, faces, colors, and symbols.

Development Test of Visual Perception, Japanese Version, 1st Edition (DTVP-1)²⁷: Adapted to assess difficulties recognizing objects affected by visual complexity, surrounding interference, and spatial location. Since this test was originally designed for children and no standardized data exist for this age group, a control group of eight healthy women in their 50 s and 60 s, employed at the same hospital as the author, was used for comparison. Statistical comparisons between the patient and this control group were conducted using Crawford & Howell's modified t-test, calculated manually. This statistical approach was selected because it allows for single-case comparison even with small control samples and has been widely used in neuropsychological case studies.

Navon Figure¹⁸: Designed to evaluate the ability to integrate constituent elements of a visual stimulus into a unified representation. The hierarchical structure of the Navon figure, which incorporates both global and local features, allows assessment of visual processing biases.

Influence of visual object complexity on cognition

The impact of visual object complexity on visuoperceptual performance was examined by comparing object-naming tasks using line drawings across three tests: VPTA, COGNISTAT, and SLTA. These tests included 8, 9, and 20 line drawings, respectively. The complexity of line drawings used in each test was broadly categorized based on factors such as the number of lines, intersections, and symmetry.^28,29 Representative examples of line drawings, recreated in a style consistent with each test's original design, are presented in Figure 3. The VPTA included the simplest drawings, characterized by minimal lines and intersections, high symmetry, and basic geometric forms (e.g., a ball, bat, spoon, and candle). In contrast, the COGNISTAT featured moderately complex, realistic line drawings (e.g., an octopus and a xylophone), with more intricate line work, a greater number of intersections, and lower symmetry. The SLTA, on the other hand, contained the most visually complex and asymmetrical images, incorporating depth and three-dimensional effects through shading (e.g., a goldfish and an airplane). These drawings exhibited a high density of visual detail and closely resembled detailed sketches, rather than simplified or abstract figures.

Results

Neuroimaging findings

Structural MRI revealed atrophy of the left occipital lobe with enlargement of the adjacent lateral ventricle, consistent with left-dominant occipitotemporal atrophy (Figure 1A). Perfusion SPECT demonstrated hypoperfusion extending from the left occipital to temporal regions, predominantly affecting the left hemisphere (Figure 1B). Amyloid PET showed widespread cortical amyloid-β deposition consistent with Alzheimer's disease pathology (Figure 2A). Tau PET showed increased tracer retention in the bilateral occipital and temporal lobes and the posterior cingulate gyrus, with left hemispheric predominance (Figure 2B).

Figure 1.

(A) axial (upper row) and coronal slices (lower row) from magnetic resonance imaging. T1-weighted sequences show cortical atrophy, especially in the left occipital lobe, supported by the enlargement of left occipital horn of lateral ventricle. R = right hemisphere; L = left hemisphere. (B) Single photon emission computed tomography. It revealed a significant reduction of cerebral blood flow in the occipital and temporal lobes, predominantly on the left side.

Figure 2.

Positron emission tomography (PET) with amyloid-beta (A) and tau aggregates (B). PET images with ¹¹C-PiB showed a diffuse accumulation of amyloid beta in the entire cerebral cortex. Notably, tau PET with ¹⁸F-florzolotau demonstrated an occipital predominant pattern with an accumulation of tau aggregates in the bilateral temporal, occipital and the posterior cingulate.

Figure 3.

What she can recognize and what she can not. (A) Hiragana and kanji. Both mean “key” and are read as “kagi.” Kanji has more strokes and is more complex. (B) Copying. A cube was accurately copied; the flower took time and included extra stems (arrows) and incorrect petal count. Hiragana for “pencil” was accurately copied; the kanji version was misrepresented. (C) Visual complexity. A fork drawing created by ChatGPT, consistent in style with the original VPTA figure, displays high symmetry and few lines or intersections. Conversely, an illustration of a goldfish from the SLTA, stylized by ChatGPT to preserve the original line drawing's features, has a high complexity that can lead to the fins being misidentified as flags. (D) Background interference. Overlapping figure created by ChatGPT, resembling the original VPTA figure. While a rhombus is easily recognizable in isolation, it becomes challenging to extract when embedded in a complex background. (E) Local feature inference. Both illustrations, an octopus and a stethoscope from COGNISTAT stylized by ChatGPT, retain the original line drawing features. Despite its complexity, the octopus can be identified by focusing on distinctive features such as suction cups, whereas the stethoscope is more challenging to recognize based solely on its tube.

General cognitive and intellectual functioning

The results of the general cognitive and intellectual assessments are summarized in Table 1. The subject scored 24 out of 30 points on the MMSE, losing five points due to difficulties with serial sevens and pentagon copying. Although she lost one point for disorientation, her memory remained intact.

Table 1.

Results of neuropsychologial assessment for intellectual functioning.

test	Type of index	Patient's score (/full score)	Control mean (SD) or range
MMSE^a	24 (30)	29.0 (1.2)
COGNISTAT^b	Orientation	10	≧9
(standard score)	Attention	10	≧9
	Linguistic tasks
	Comprehension	7	≧9
	Repetition	6	≧9
	Naming	9	≧9
	Construction	5	≧9
	Memory	8	≧9
	Calculation	10	≧9
	Similarities	9	≧9
	Judgement	11	≧9
WAIS-Ⅳ (IQ)^c	VCI	72	70–130
	PRI	62	70–130
	WMI	85	70–130
	PSI	50	70–130

MMSE: Mini-Mental State Examination; WAIS-Ⅳ: Wechsler Adult Intelligence Scale – Fourth Edition; IQ: Intelligence Quotient; FSIQ: Full Scale Intelligence Quotient; VCI: Verbal Comprehension Index; PRI: Perceptual Reasoning Index; WMI: Working Memory Index; PSI: Processing Speed Index. Abnormal values are shown in bold. aThe control data are based on the Japanese edition of the MMSE manual, and are obtained from healthy people aged between 55 and 74. bThe score is standardized: 9 or higher = normal; 8 = mild disability; 7 = moderate disability; 6 or lower = severe disability. cThe score is expressed as an IQ, with an average of 100 and a standard deviation (SD) of 15 in the cognitively intact population. A range of 70 to 130 is considered normal.

On the COGNISTAT, her attention scores were normal, as assessed by a digit span forward task evaluating immediate auditory attention and short-term storage, ruling out the possibility of generalized attentional dysfunction affecting the results of other tests. Her memory performance was also relatively preserved, as assessed by delayed recall of four words reflecting verbal episodic memory. However, in the naming objects task using line drawings, she misidentified a stethoscope as “something like a long, thin cord” despite correctly recognizing objects such as a shoe and an octopus. Additionally, during the scene description task, she struggled to integrate the components of the picture into a coherent whole. The picture depicted a fisherman dozing on grass while another person, at a considerable distance, was attempting to alert him that his fishing rod had caught a fish. Her description of the scene was as follows:

“There is a pond. There is grass. A child is sleeping on grass, and a boy is saying something with his right hand outstretched. There is a carp. I think the carp is a sculpture.”

This response indicated her inability to associate the carp with the pond or the background context. Despite this limitation, she was able to view the entire picture and grasp the approximate identity of each individual element.

In the language-related subtests of the COGNISTAT, mild to moderate deficits were observed in auditory comprehension and sentence repetition. In the auditory comprehension task, which required following verbally presented instructions involving manipulation of objects placed before her, she occasionally had difficulty executing multi-step commands. Sentence repetition was also mildly impaired: while repetition of short phrases was preserved, she showed hesitations and occasional word substitutions or omissions when repeating sentence-length stimuli, suggesting a limitation of auditory verbal short-term memory.

On the WAIS-IV subtests, she exhibited significant declines in perceptual reasoning (IQ 62) and processing speed (IQ 50), which assess non-verbal functions requiring accurate visual perception. In contrast, her verbal functions, which are relatively independent of visual perception, were only mildly impaired, with scores of IQ 72 for verbal comprehension and IQ 85 for working memory.

Language functioning

The SLTA results indicated no significant evidence of aphasia, particularly in speaking and listening domains. However, tasks requiring precise visual perception, such as reading and picture-naming, demonstrated marked impairments attributable to visual agnosia and alexia rather than deficits in language processing itself.

Picture-Naming Task (line drawings): She exhibited picture agnosia, frequently misidentifying objects based on localized parts or shapes. For instance, she misidentified an airplane as a pen (inferred from its nose) and a goldfish as a flag (inferred from its tail fin).

Reading Task: Her performance reflected severe alexia characterized by features reminiscent of the early stage of letter-by-letter reading. She experienced particular difficulty with kanji (logographic Chinese characters), which are more complex in glyph structure compared to hiragana (syllabic phonographic characters). For example, while she could read the word kagi (meaning “key”) written in hiragana but was unable to read the corresponding kanji character with the same pronunciation and meaning (Fig. 3A).

Comic Strip Interpretation: In a four-panel comic strip task, she struggled to understand the sequential storyline and failed to identify that the person appearing in all four panels was the same individual.

Writing Task: She exhibited mild agraphia. However, it was less severe than her alexia, because she was unable to read letters she had written herself.

Calculation Task: While she could perform simple four-digit operations without difficulty, she occasionally made errors in calculations involving carrying or borrowing digits.

Visuoperceptual functioning

The results of visual perceptual assessments are summarized in Tables 2 and 3.

VPTA: The subject demonstrated no significant problems with basic visuoperceptual functions, such as discriminating lengths, shapes, and line slopes, as well as naming faces and colors. Contrary to expectations, she successfully recognized all line drawings in this task, as they were inherently very simple and clearly drawn. However, she demonstrated severe impairments in tasks involving overlapping figures, where she struggled to isolate individual shapes from overlapping elements. Copying tasks revealed a pronounced dependency on the complexity of the sample: the more intricate the figure or letter, the longer it took her to replicate and the more fragmented her reproductions became. Notably, while she copied hiragana characters (syllabic phonographic characters) without difficulty, she made a distinctive error in the kanji (logographic characters) copying task in which she combined partial elements of two different characters and recognized them as a single character (Fig. 3B). In contrast, in the reading tasks, she exhibited not only frequent misreadings or delayed responses for kanji but also occasional errors for hiragana, which are relatively simple phonographic characters. These hiragana errors were not attributable to visual complexity per se but reflected her reliance on partial visual features without integrating them into a unified whole, leading to confusions with visually similar characters. In the picture comprehension test titled “false accusation,” which depicted a girl in the center whose donut was being stolen by a boy on the left, while a girl on the right was being falsely accused, she accurately described individual components, such as the gender and the food. However, she failed to grasp the relationships among the elements. Her response was:

"Here are three close children getting together. The boy only thinks about eating donuts. This girl has one donut, but another girl has two, so she is angry."

This statement reflected an inability to identify the overarching theme or relationships within the scene.

DTVP-1: Control data indicated that nearly perfect scores are typical for healthy women in this age group. The individual exhibited significant challenges in visuoperceptual tasks. Her errors on the constancy-of-shape subtest—requiring her to distinguish a circle from ovals or a square from rectangles—and her failures even on relatively simple items of the figure–ground subtest suggested that elementary shape perception was not entirely preserved. However, her most striking impairment was on the figure–ground subtest overall, where performance declined markedly as the backgrounds became denser and more cluttered. This indicated that even simple figures, which she could recognize in isolation, became increasingly difficult to identify when embedded within visually complex arrays. In contrast, her visuospatial cognition was relatively intact. For instance, in the eye-motor coordination task, which required her to draw lines within a given width, and the spatial relations task, which involved connecting dots based on a model, her performance was within the expected range.

Navon Figure: The subject exhibited a strong local processing bias with impaired global integration. While she could identify local letters by tracing them with her finger, she failed to recognize the larger, global letter, even after being explicitly informed of its presence.

Table 2.

Results of neuropsychological assessment for visual perceptual functioning, VPTA.

test	type of index	Patient's score/full score	Control mean (SD)
VPTA	Fundamental visual functining
(raw score)	Length of line segments	10/10	10.0 (0.00)
	Counting of scattered dots	5/6	6.0 (0.00)
	Discrimination and matching of configuration	11/12	11.7 (0.80)
	Slope of line segments	5/6	5.9 (0.64)
	Overlapping figures	0/6	6.0 (0.40)
	Copying of figures	3/6	5.7 (0.72)
	Cognition of objects and visual images
	Naming of visual images	15/16	16.0 (0.14)
	Naming of objects	16/16	16.0 (0.00)
	Picture comprehension	4/8	6.9 (1.96)
	Cognition of faces
	Naming of famous faces	12/16	15.2 (1.95)
	Discrimination of unfamiliar faces	8/8	7.4 (1.12)
	Matching of unfamiliar faces	5/6	5.9 (0.27)
	Emotional epression	6/6	6.0 (0.14)
	Cognition of colors
	Color naming	16/16	15.6 (1.24)
	Color matching	16/16	16.0 (0.38)
	Cognition of symbols
	Cognition of letters (Kanji)	11/12	11.9 (0.44)
	Cognition of letters (Hiragana)	10/12	12.0 (0.27)

VPTA: Visual Perception Test for Agnosia; SD: standard deviation. To ensure consistency with the other tables, scores are now presented in a “score/full score” format, where higher values indicate better performance. Values falling below the mean −2SD are bolded as abnormal. The control data are based on the Japanese edition of the VPTA manual. Reference values for all subitems are approximately zero.

Table 3.

Results of neuropsychological assessment for visual perceptual functioning, DTVP-1.

DTVP-1 subtest	patient (correct/max)	control (mean ± SD)	crawford test (vs controls)
Eye-motor coordination	20/30	29.3 ± 0.71	t(7) = －12.33, p = 5.29×10^-6
Figure-ground	2/20	19.6 ± 0.5	t(7) = －32.11, p = 7.35×10^-9
Constancy of shape	11/17	16.0 ± 0.93	t(7) = －5.09, p = 1.41×10^-3
Position of space	7/8	controls all 8/8	not applicable
Spatial relationships	5/8	controls all 8/8	not applicable

DTVP-1: developmental test for visual perception – first edition. The results demonstrate that while the patient showed impairments across several subtests, the deficit was most severe in the figure–ground discrimination task. Other subtests such as constancy of shape, eye–motor coordination, and spatial relations also showed significant impairments, though less extreme. For some subtests, statistical comparison with controls was not applicable because all control participants achieved ceiling scores, making variance estimates impossible.

Influence of visual object complexity on cognition

A focused analysis of line-drawing naming tasks across various tests revealed error rates of 0/8 (0%) for the VPTA, 1/9 (11%) for the COGNISTAT, and 3/20 (15%) for the SLTA. The discrepancies in performance across these tests appear to stem from variations in the complexity of the line drawings. This interpretation is supported by her performance on copying tasks, where accuracy decreased and completion time increased as figure complexity rose (Figure 3B). Detailed assessments of her visual perceptual deficits and alexia revealed a tendency to perceive objects, letters, and images in fragmented parts rather than as cohesive wholes. This fragmentation often led to misrecognition or perceptual errors, particularly when objects featured complex shapes or were presented against cluttered backgrounds.

To provide an integrated overview of the individual's impairments across domains, we compiled an Impairment Summary Table (Table 4). This table presents her performance on object recognition, scene comprehension, and reading tasks, expressed in a uniform “score/full score” format with corresponding control values. The summary highlights that, although basic shape recognition was not entirely preserved, her most disabling impairments consistently appeared under conditions of high visual complexity, background interference, or part–whole integration.

Table 4.

Impairment summary table. Individual's performance is reported as score/maximum (%) whenever applicable. Control/norm values are shown as either raw scores, mean values, or approximated ceiling performance (≈100%). Bolded entries in the Impairment column indicate clinically severe deficits. Reading performance combines SLTA and VPTA results, reflecting that both kanji and hiragana were affected, although kanji was more impaired.

Domain / test	Subtest / measure	Individual's score / performance	Control / norm	Impairment
Basic visual perception (VPTA)	Length discrimination	Near perfect	Near perfect	No
	Shape recognition	Near perfect	Near perfect	No
	Line slope discrimination	Near perfect	Near perfect	No
	Face & color naming	Near perfect	Near perfect	No
	Overlapping figures	Poor	Near perfect	Yes (severe)
	Copying (complex figures/letters)	Fragmented, slow	Near perfect	Yes
DTVP-1	Figure–ground discrimination	2/20 (10.0%)	19–20/20 (n=8)	Yes (severe)
	Constancy of shape	11/17(64.5%)	mean 16.0/17 (n=8)	Yes (mild)
	Eye–motor coordination	20/30 (66.7%)	mean 29.3/30 (n=8)	Yes (mild)
	Spatial relationship (dot connection)	5/8 (67.5%)	All controls 8/8 (n=8)	Yes (mild)
Object recognition	VPTA line-drawing naming (simple)	8/8 (100% correct)	∼100%	No
	COGNISTAT line-drawing naming (moderate)	1/9 (11% correct)	∼100%	Yes
	SLTA line-drawing naming (complex)	3/20 (15% correct)	∼100%	Yes
Reading (SLTA and VPTA)	Hiragana (phonographic, typically simple in visual form)	delayed with occasional confusions	Normal	Yes
	Kanji (logographic, typically complex in visual form)	impaired (slow, fragmented, errors)	Normal	Yes
	Reading style	features reminiscent of early letter-by-letter reading	N/A	–
Scene comprehension	Picture comprehension (various tasks)	Fragmented, incoherent	Normal	Yes
	Comic strip	Failed storyline integration	Normal	Yes
Global–local processing	Navon figure (local letters)	Intact (traced with finger)	Normal	No
	Navon figure (global letter)	Failed (even when cued)	Normal	Yes

Intervention and follow-up

The individual fulfilled clinical and imaging-based criteria for PCA due to Alzheimer's disease supported by amyloid-β and tau PET findings.⁵ She was initially prescribed donepezil, but the treatment was discontinued due to nausea.

Over time, her visuoperceptual cognitive impairments gradually worsened, and even reading simple letters became significantly more time-consuming. She also began to exhibit symptoms of visuospatial cognitive impairment, such as occasionally writing outside designated spaces on forms. Despite these deficits, the impact on her daily life remained relatively mild. Notably, her memory impairment remained minimal, even two years after the initial diagnosis. She demonstrated relatively preserved auditory memory and learning abilities, as evidenced by her capacity to learn and play new pieces of music with the aid of auditory guidance.

Discussion

This case describes an individual with PCA whose chief complaint was a clinically observed difficulty reading chords in musical scores, despite no difficulty reading individual notes. Although she could visually apprehend the spatial configuration of multiple notes simultaneously, she could not integrate them into a meaningful whole (“a chord”), which is why she experienced them as “jumbled up.” This dissociation indicates that her symptoms cannot be explained by dorsal simultanagnosia, which is defined by the inability to perceive more than one object at a time. This interpretation is further supported by the absence of daily life symptoms typically associated with dorsal visuospatial dysfunction, such as difficulty navigating, grasping objects, or avoiding obstacles. She also exhibited prominent visuoperceptual deficits. Her difficulty in reading chords should therefore be understood in the context of these visuoperceptual impairments.

Chord recognition and ventral simultanagnosia

Reading chords requires the ability to perceive and process multiple visual elements and their relationships, such as individual notes, supplementary symbols (e.g., ♭), and the five-line staff. In this light, her difficulty in reading chords could be attributed to ventral simultanagnosia. Both dorsal and ventral simultanagnosia share the common feature that patients cannot simultaneously recognize multiple visual stimuli. However, their mechanisms differ: in dorsal simultanagnosia, only one object can be perceived at a time, whereas in ventral simultanagnosia, multiple objects may be perceived simultaneously but cannot be integrated or categorized into a coherent whole.^16,30 In our case, the individual was able to visually apprehend several notes at once, indicating that dorsal simultanagnosia was not present. Instead, her difficulty lay in integrating them into the higher-order structure of a chord, a pattern more consistent with ventral simultanagnosia. This account is supported by her difficulties with four-panel comic strips and scene-description tasks, and by her strong local processing bias in the Navon figure task—a phenomenon frequently associated with ventral simultanagnosia.³¹ Nevertheless, ventral simultanagnosia alone does not fully account for her symptoms, as she also exhibited dense object agnosia even for single complex items, which goes beyond the typical presentation of ventral simultanagnosia.

Integrative visual agnosia: a more plausible explanation

A more likely explanation for her visual cognitive impairment is integrative visual agnosia.³² Unlike previous cases of ventral simultanagnosia, this case is characterized by dense object agnosia—the inability to recognize even a single visual object with substantial visual complexity. Moreover, her local bias in the Navon figure task, when viewed as an isolated visual object, suggests an inability to integrate features of the parts into a cohesive whole.

Although her performance on some DTVP-1 subtasks and delayed recognition of single hiragana characters (a relatively simple phonographic script) indicates that lower-level visual processes such as form agnosia and visual crowding cannot be completely excluded,^33,34 the pattern of her deficits suggests that these factors alone cannot fully account for her symptoms. Visual crowding, which typically affects peripheral vision where nearby flankers interfere with target recognition,^35,36 may appear to explain her “jumbled” perception of adjacent notes. However, her difficulties were evident even for centrally presented stimuli, including line drawings, written characters, and musical chords. The consistency of these complexity-dependent impairments across stimulus types suggests a domain-general deficit in visual integration rather than stimulus-specific interference, more characteristic of integrative visual agnosia.^32,37 Taken together, her clinical picture is more consistent with integrative visual agnosia—a breakdown in constructing visual representations from parts to wholes. This framework provides a useful basis for understanding the present case in light of the established characteristics of integrative visual agnosia.

Integrative visual agnosia represents an expansion of Lissauer's apperceptive-associative dichotomy, as suggested by Riddoch and Humphrey.³⁸ It results from an impairment in constructing visual representations during the process of visual cognition, preventing the grouping of local elements into perceptual wholes. Several features of integrative visual agnosia align with this case:

Complex Visual Objects³⁹: The recognition and copying of morphologically complex objects or letters composed of multiple lines or parts were particularly challenging for her (Fig. 3B, 3C). She performed normally for simple shapes but showed marked difficulty as visual complexity increased.

Background Interference⁴⁰: In complex scenes where objects overlapped with backgrounds, she had difficulty discriminating foreground elements, as demonstrated in the overlapping figure in the VTPA and figure-ground tasks in the DTVP-1 (Fig. 3D).

Local Feature Inference⁴⁰: She tended to infer the whole object based on localized features, such as identifying an airplane as a pen (based on its nose) or a stethoscope as “something like a long, thin cord” (based on its tube). Interestingly, she successfully identified an octopus in a line-drawing task, likely because its unique morphological features (e.g., suckers) facilitated recognition, unlike the simpler geometric shapes of the airplane and stethoscope (Fig. 3E).

Implications for chord recognition

The inability to read chords can also be interpreted in the context of integrative visual agnosia. Chords are perceived as a single entity rather than a series of independent notes. Thus, her difficulty likely stems from the complexity of their configuration, interference from the five-line staff as a background, and her inability to infer the whole from its parts. Beyond this descriptive account, chord recognition can be conceptualized within established models of hierarchical visual processing. From a cognitive perspective, chord reading may be understood as a form of vertical visual integration analogous to global processing in Navon-type hierarchical stimuli.¹⁸ Just as integrative visual agnosia disrupts the grouping of local elements into coherent object representations,³² chord recognition requires the binding of simultaneously presented notes into a unified harmonic structure. This process aligns with principles of visual Gestalt organization and hierarchical perceptual encoding.¹⁹ The present case therefore illustrates how musical notation may serve as an ecologically valid probe of impaired hierarchical visual integration in occipitotemporal PCA. Importantly, this parallel does not imply that chord recognition is identical to Navon-type processing at a representational level. Rather, they share a common computational demand: the integration of spatially distributed elements into a coherent global percept. In this sense, chord reading represents one specific manifestation (in the musical domain) of a more general mechanism responsible for integrating parts into wholes.

Beyond the present case, these findings have broader implications for understanding visuoperceptual dysfunction in posterior cortical atrophy. While most clinical descriptions emphasize visuospatial impairments associated with the dorsal visual stream, disturbances of hierarchical visual integration within the ventral stream may be more subtle and therefore underrecognized. The present case suggests that tasks requiring the integration of multiple visual elements into a structured whole—such as musical chord reading—may offer clinically useful probes for detecting subtle impairments in hierarchical visual integration. Greater attention to these types of impairments may contribute to earlier recognition of occipitotemporal variants of PCA and help refine current models of visual cognition in neurodegenerative disease.

Neurological basis of integrative visual agnosia

The anatomical basis of integrative visual agnosia remains underexplored. Although theoretical accounts have been proposed—most notably by Riddoch and Humphreys, who developed influential models based on detailed single-case analyses^32,33—consistent neuroanatomical evidence distinguishing integrative visual agnosia from other forms of visual agnosia is still lacking. To our knowledge, this appears to be among the first descriptions of integrative visual agnosia associated with a degenerative disease.

A prior study using diffusion tensor imaging in patients with PCA revealed a correlation between higher diffusivity and lower fractional anisotropy in the left inferior longitudinal fasciculus (ILF) and inferior fronto-occipital fasciculus—key tracts in the ventral visual pathway—and visual agnosia, including object perception deficits.⁴¹ The ILF, in particular, plays a pivotal role as a white matter tract linking the lateral occipital cortex to the anterior temporal lobe. This connection is crucial for transmitting detailed visual information essential for object recognition.⁴² By integrating visual inputs from the occipital regions with semantic and contextual processing in the temporal lobe, the ILF enables the construction of coherent object representations and the interpretation of visual stimuli within a broader perceptual and memory framework.⁴³ Given this role, disruption of this pathway is likely to contribute to severe visual perceptual deficits, such as those observed in integrative visual agnosia, in line with Ungerleider and Mishkin's seminal proposal of a ventral “what” stream for object identification.⁷

More recent theoretical frameworks emphasize the role of attentional mechanisms across different spatial scales. Whitwell et al. introduced the concept of “scale attention,” the selective allocation of attention within and between hierarchical levels of visual information (e.g., local versus global features, parts versus wholes, or objects versus scenes).⁴⁴ They proposed that failures of scale attention may underlie integrative deficits and identified posterior vertical white matter pathways—such as vertical segments of the superior longitudinal fasciculus—as likely substrates linking parietal attentional centers with occipito-temporal perceptual hubs. In the present case, the individual's inability to perceive multiple notes as a coherent musical chord may reflect not only ventral stream disruption, such as of the ILF, but also impaired scale attention mediated by these vertical pathways.

In the present case, structural MRI and perfusion SPECT demonstrated atrophy and hypoperfusion involving the lateral occipital cortex, findings consistent with involvement of occipito-temporal regions hypothesized to contribute to integrative visual processing. However, we did not obtain direct evidence of white matter tract involvement in the ILF or in the vertical segments of the superior longitudinal fasciculus. The individual's clinical profile nonetheless suggests that disconnection in these pathways may plausibly contribute to her deficits.

Pathological findings

PET imaging revealed widespread cortical retention of amyloid-β on ¹¹C-PiB PET and significant tau accumulation on ¹⁸F-florzolotau PET, primarily in the occipital and temporal cortex as well as the posterior cingulate gyrus, consistent with Alzheimer's disease pathology. Notably, tau deposition, which has been reported to correlate more strongly with symptom severity and neuropsychological test results than amyloid accumulation,⁴⁵ was concentrated in posterior brain regions, particularly within the occipitotemporal visual association cortices. These pathological findings strongly support a diagnosis of PCA attributable to Alzheimer's disease and provide a pathological basis for the observed integrative visual agnosia.

Limitations

This report has several limitations. Because PCA is a degenerative disorder, the individual's impairments cannot be cleanly separated into discrete categories, although her core deficit appeared to be integrative visual agnosia. First, we cannot fully exclude the contribution of lower-level perceptual impairments such as form agnosia or visual crowding, which may have interacted with higher-order deficits and complicated the clinical picture.^34,40 However, their relative contribution was not quantitatively assessed, and no formal measures of visual complexity were obtained. Moreover, the figure–ground subtest itself engages both lower-level processes such as background segregation—identified by Riddoch as characteristic of form agnosia³³—and higher-level demands involving part–whole integration.⁴⁰ Because her errors could not be clearly attributed to one or the other, both mechanisms may have contributed. A more systematic, quantitative evaluation across varying levels of visual complexity and overlap would therefore have been valuable, and this remains an important limitation. Second, her marked difficulty in grasping the overall meaning of pictures and comic strips suggests strong elements of ventral simultanagnosia.⁴⁶ In fact, the distinction between ventral simultanagnosia and integrative visual agnosia may be somewhat arbitrary, with both characterized by the inability to integrate dense visual objects with complex information. The key difference between them may lie in context: ventral simultanagnosia pertains to deficits in processing multiple visual stimuli, whereas integrative visual agnosia refers to deficits in processing a single complex visual stimulus. Third, the core symptom of chord-reading difficulty was assessed only through qualitative clinical observation in a naturalistic context, using the patient's own musical scores. No formal quantitative testing was conducted, and the interpretation of this finding should therefore be regarded as provisional. Specifically, her slowed recognition of individual letters suggested features of early-stage letter-by-letter reading, and her chord-reading difficulty may represent a parallel phenomenon in the musical domain. From this perspective, quantitative measures such as reading latency in relation to word length or chord complexity would have provided valuable support,⁴⁷ but these were not collected.

Conclusions

This case highlights an individual with PCA who exhibited difficulty reading chords on music sheets, despite being able to perceive their overall shape and successfully read individual notes. Her disproportionate chord-reading difficulty is most consistent with integrative visual agnosia—a failure to synthesize visual parts into a coherent whole—which offers unique insights into the visuoperceptual challenges faced by patients with PCA.

Footnotes

Acknowledgements

We sincerely thank the individual for her participation and cooperation in this study. We also extend our gratitude to TK, who works for an external institute, for accommodating our request for a PET scan. In accordance with SAGE policy on AI-assisted writing, during the preparation of this work the author used ChatGPT, in order to revise the manuscript, such as enhancing the naturalness of English expressions and correcting grammar. After using this service, the author reviewed and edited the content as needed and takes full responsibility for the content of the publication.

ORCID iDs

Hiroyuki Ogino

Michitaka Funayama

Ethical considerations

The authors declare that ethics approval was not required for this case report.

Consent to participate

Written informed consent was obtained from the individual for participation in this case report.

Consent for publication

The individual provided written consent for the publication of this case report and any accompanying images.

Author contribution(s)

Hiroyuki Ogino: Conceptualization; Investigation; Methodology; Visualization; Writing – original draft; Writing – review & editing.

Fumie Saito: Conceptualization; Formal analysis; Investigation; Methodology; Writing – review & editing.

Keisuke Takahata: Data curation; Formal analysis; Formal analysis; Resources; Visualization; Writing – review & editing.

Masanori Ichihashi: Formal analysis; Formal analysis; Resources; Writing – review & editing.

Yuki Momota: Data curation; Formal analysis; Formal analysis; Resources; Writing – review & editing.

Mirai So: Conceptualization; Methodology; Writing – review & editing.

Masaru Mimura: Methodology; Supervision; Writing – review & editing.

Michitaka Funayama: Formal analysis; Supervision; Validation; Writing – review & editing.

Funding

This study was supported by AMED (Grant Number 24wm0625304s0101).

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data availability statement

Data supporting the findings of this study are available from the corresponding author upon reasonable request, with appropriate safeguards for participant confidentiality.

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