Constructional, Perceptual, and Spatial Abilities

Visual Perceptual and Spatial Processing

Perceptual and spatial analysis occurs along a route from sensory input to a complete representational reconstruction of the visual world. A careful mental status examination can localize perceptual and spatial disturbances along this route. Visual primitives, such as line orientation and edge detection, contrast and spatial frequencies, luminance and color contrasts, and ocular dominance emerge in V1 (Brodmann area [BA] 17), the occipital striate cortex. Most importantly for mental status assessment, at this level, two cortical visual pathways, the ventral or “what” stream and the dorsal or “where stream,” begin to emerge ( Fig. 10.1 ). The ventral stream continues to V2 (BA18), an area involved in figure-ground analysis and other functions, through V4, an area involved in simple shape and color recognition, and ultimately to the inferior temporal cortex and object recognition. Hence ventral stream abnormalities affect basic perceptual processing and result in visual object agnosias, topographagnosia, color agnosia, and prosopagnosia. From V1, the dorsal stream continues to V2 (BA18) and dorsal V3 (BA19) involved in spatial location. A part of the dorsal stream (the “ventrodorsal” pathway to V5 [middle temporal] and inferior parietal cortex) participates in the perception of motion and the guidance of some  eye movements. Dorsal stream abnormalities affect some basic perceptual processing and all spatial processing and result in hemispatial neglect, dressing “apraxia,” topographic disorientation, and Balint syndrome.

Examination of Constructional Abilities

On the mental status examination, the easiest way to screen for perceptual or spatial disturbances is through paper and pencil constructional tasks. Constructional tests include simple geometric figure copies, complex figure copy, free drawing, and clock drawing. These tests are easy to administer, do not require special stimuli for the most part, and are sensitive to disorders anywhere along the ventral and dorsal streams. Right hemisphere disorders tend to result in fragmented constructions with loss of overall spatial relations and orientation, whereas left hemisphere disorders tend to result in impoverished constructions with omission of essential features or lines. Many persons have not had occasion to draw or copy figures in decades. With these subjects, it may be more accurate if they are given one practice trial, or, in some cases, have them view you as you make the figures (marked improvement in this second process may also reflect frontal lobe executive dysfunction). Finally, many clinicians describe a failure to normally copy these figures as constructional “apraxia”; however, they are best described as constructional disturbances because they are not primary disturbances of motor programming.

Simple Figure Copy. Most examiners ask the patient to copy a simple two-dimensional figure such as a circle or a diamond, a complex two-dimensional figure such as a rectangle, or three-dimensional figures such as a box, cube, or napkin holder (“Benson figure”) ( Fig. 10.2 ). For the best constructional task performance, the examiner must be prepared beforehand. Rather than quickly drawing a stimulus on a lined progress note paper, it is best to have a preprinted design for copy, blank and unlined white sheets of paper, and a black pen or a pencil without eraser. The introductory instructions include: “Please make a copy of the picture exactly as you see it.” Those who make errors and wish to start over again should be allowed to do so but keeping both copies.

There are different methods for grading the drawings. The examiner looks for abnormal or fragmented spatial relationships, absence of detail or impoverished essential features, stimulus-boundedness (“closing-in” or drawing over the master copy), loss of three-dimensional perspective, or neglect of one part of the drawing. For simpler constructions, there are suggested grading systems for the copy of a circle (closed to within 1/8” = 1; circular = 1); of a diamond (4 sides = 1; 4 closed angles = 1; sides of equal length = 1); and of a rectangle (both figures 4-sided = 1; overlaps resembles original = 1). For the cube and Benson figure, a suggested grading system is included in Fig. 10.2 .

Complex Figure Copy. The Rey-Osterrieth Complex Figure is the best known complex figure test ( Fig. 10.3 ), but there are alternative ones, such as the Taylor figure and others. These constructional tasks have the advantage of having a formal scoring system and normative data for assessing the patient’s performance. The examiner gives the patient a blank piece of paper and places the stimulus figure in front of him or her. The complex figure task requires the patient to copy the entire figure as best as he or she can, and, although not given a time limit, the patient receives encouragement to complete it. To assess strategy, the examiner may change the patient’s pencil or pen to different colored ones at different points in the drawing, thus indicating the sequence and strategy for copying the figure. The scoring system includes 18 specific items (Chapter 17, Fig. 17.1). As an additional visual memory task, they may reproduce the complex figure from memory ( Chapter 9 ), and the strategy for completion can be further analyzed as an executive task (Chapter 13).

Freehand Drawing Tasks. These tasks add the element of visual imagery and remove the guide of a predetermined drawing to copy. The examiner provides the patient with a blank sheet of paper and instructs the patient to draw a house, a dog, a flower (e.g., a “daisy in a flowerpot”), or even a person (the “draw-a-person” test). The patient instructions are: “I would like you to draw simple pictures. I know that you may not be an artist, but please draw the pictures as well as you can.” Evaluate the drawings in terms of the features noted for simple figural constructions. In addition to perceptual and spatial disturbances, these drawings can also reflect semantic deficits (see Chapter 9 ).

Clock Drawing. The freehand drawing of a clock is a sensitive measure of perceptual and spatial difficulty, but it is also affected by attention, language comprehension, numerical knowledge, and executive functions. It can be administered in a number of ways, but the best may be the presentation of a blank piece of paper with the instructions to simply “draw a clock.” After the patient draws the clock circle with the numbers, the examiner then has the patient put in the hands to read “10 after 11” or, alternatively, “5 past 4.” There are many scoring systems for the clock, some of which attempt to distinguish the different cognitive functions that impact on clock drawing ( Table 10.2 ). The easiest is to evaluate for the contour of the circle, the order and quadrant placement of the numbers (which can be within or outside of the circle), and the presence of two hands, a short hour hand and a long minute hand, meeting near the center of the clock face ( Fig. 10.4 ).

The examiner, where indicated, may want to test constructional ability with additional tests, such as block assembly and picture arrangement. Most of these tests, however, require special stimuli or procedures for testing and scoring performance and are highly dependent on visuomotor coordination and basic motor ability. For example, block construction can employ four Koh’s blocks, which have sides that are red, white, or half red and half white. The examiner presents pictures of different four-block arrangements and asks the patient to take the blocks and make a design that looks like the pictures. Cut-up pictures can also be arranged, much like a jigsaw puzzle. The examiner can use other constructional tools, including tinker toys and readily available items such as match sticks or toothpicks, for freehand constructions. One additionally potentially useful constructional task that does not require blocks or constructional tools is paper-folding. The examiner folds the paper in different ways, for example, exactly in half, quarters, two triangles, along the diagonal, et cetera, and asks the patient to fold their paper in an identical way.

Examination of Basic Perceptual Abilities

Basic Visual Form Discrimination. If more in-depth testing is needed, the examiner evaluates basic perception. When viewing images, people must be able to recognize form at the basic, geometric level. The reconstruction and eventual recognition of basic forms and shapes is a process that underlies the ability to recognize objects, which are made up of basic forms and shapes. The easiest screen is to have the patient match two or three previous constructions with the correct choice out of a field of different geometric forms ( Fig. 10.5 ). The examiner should note whether, in matching the figures, the patient uses a slow, feature-by-feature analysis rather than a rapid global analysis of configuration. This evaluation can also include a multiple-choice matching task using complex forms or shapes or objects in unconventional views. Each figure is presented with four other match figures varying in shape, rotation, or distortion of the figure, and the patient is asked to indicate which match figure corresponds to the stimulus figure. An alternative screening procedure, which is also easy to do in a clinical encounter, is to ask the patient to identify figures obscured by cross-hatching ( Fig. 10.6A ). This screen overlaps with figure-ground tests.

Figure-Ground D iscrimination. When viewing images, people experience some figures projecting into the foreground, whereas others recede into the background. The brain organizes the visual field into figures that stand out from their surroundings (ground). Often “figure” and “ground” alternate or compete with each other. This figure-ground processing, which is evident at the V2 level, is a basic perceptual process that can be tested with hidden or embedded figures ( Fig. 10.6B ). The patients may also identify three or four overlapping figures made up of overlapping line drawings, originally popularized as the Poppelreuter figures test.

Visual Integration and Global-Local Processing. When viewing images, people automatically organize what they see into figures, objects, and scenes. This process of integration allows for the apprehension of intact figures from dilapidated or incomplete ones. The inability to apprehend and integrate at the single form or object level is sometimes called “integrative agnosia,” which is related to the inability to apprehend and integrate multiple objects at a scene level. The examiner tests visual organization with incomplete or cut-up drawings ( Fig. 10.6C ). The Street Figures are part of the original Street Completion Test and consist of incomplete pictures that have been used to examine perceptual integration. Alternatively, the examiner can present cut-up pictures such as compose the Hooper Visual Organization Test. The cut-up figures are fragmented objects that have to be reconstructed mentally. Global-local processing is easily tested with the “Navon” figures, which consist of letters or numbers made up of smaller letters or numbers ( Fig. 10.6D ). Patients may recognize the smaller numbers or letters and miss the global one. Finally, it is important to present a complex drawing to the patient (also part of visual search testing), generally representing a familiar scene ( Fig. 10.7 ), and assess whether the patient can identify the whole theme or situation, as well as the constituent parts.

In special situations, the examiner may want to test perceptual ability with additional tests that evaluate top-down processing. In particular, perception undergoes top-down interpretation exemplified by gestalt inferences including the perception of objects or grouping from proximity, similarity, continuity, connectedness, and closure. The examiner can evaluate top-down processes, including the ability to interpret and decipher illusions.

Examination of Spatial Abilities

Visual Search and Localization. The ability to localize in visual space is a fundamental dorsal stream function usually tested with picture and dot localization or search tasks. These tasks focus on the ability to scan a picture and localize a series of random items. The examiner asks the patient to scan a complex visual scene, such as Fig. 10.7 or the Cookie Theft Picture from the language examination (See Chapter 8, Fig. 8.2), for six specific items in the two general areas of the picture. The following are the specific items that can be graded on the Cookie Theft Picture: girl, boy falling, cookie jar, mother washing, sink overflowing, and window. Alternatively, the examiner asks the patient to locate and circle 20 or 40 dots within an 11- x 17-inch field ( Fig. 10.8 ).

Hemispatial Neglect Tasks. Each hemisphere controls the contralateral side of extra- and peripersonal space, and hemispatial neglect occurs when there is impaired spatial attention to the contralateral visual space, most commonly on the left. In this disorder, neglect may be evident if the patient tends to ignore the left side of the environment or the left side of his or her constructional drawings. Hemispatial neglect can also be detected in reading and writing (e.g., “horseradish” is seen as “radish” or “island” is seen as “land”). In addition, the examiner needs to keep in mind that hemispatial neglect itself, although usually centered to the midline of the patient’s body (egocentric), is occasionally object-centered (allocentric). The predominant lesion resulting in classic left-sided hemispatial neglect involves the right inferior parietal cortex (BA29, 30), but can also occur from thalamic or other locations.

Hemispatial neglect tasks include line bisection, visual search and cancellation, the gap test, and double simultaneous stimulation. First of all, it is important that the stimulus materials be oriented to the patient’s body axis. While the patient is seated, the test sheets are placed in front of the patient, aligning the center of the sheet with the patient’s midline. Second, the examiner starts with a line bisection task consisting of a test sheet with one or a series of horizontal lines differentially placed on the paper ( Fig. 10.9 ). The examiner asks the patient to divide each line in half by placing a mark at the center of each line. The score is the mean of the percent deviation from the true center of the line. On this line bisection, the degree of displacement is directly proportional to the length of the line used. Third, the patient with suspected hemispatial neglect may undergo a cancellation test. The letter cancellation test consists of a 21.6 x 28 cm white piece of paper with different letters distributed randomly across the page ( Fig. 10.10 ). The patient is instructed to circle the letter “A” (the target) every time they see that letter, and the patient’s score is determined by the number of correct targets cancelled. Fourth, the examiner may use a complex picture as a hemispatial neglect task by asking the patient to name as many objects as he or she sees in the picture. The examiner can operationalize this test by choosing 5 to 10 items in each half of the picture. Fifth, an excellent test of both egocentric allocentric neglect is the gap test ( Fig. 10.11 ). The patient must indicate (circle or cross out) all the circles with a gap. Failure to cross out all gaps on one side of the page indicates egocentric neglect, whereas failure to cross out all gaps facing either left or facing right indicates allosteric neglect. Finally, in double simultaneous stimulation, stimuli, such as fingers, are simultaneously presented or held up in each hemifield, and the examiner asks the patients to report the number of objects or fingers while maintaining their gaze fixed on the examiner. Unilateral extinction occurs when the patients fail to detect the stimuli on one side.

There are other forms of neglect, including sensory, motor, and conceptual. Sensory neglect is a disturbance of the personal body map with inattention to the half of the body, such as a tendency to dress and groom one side of the body while ignoring the other. Motor neglect includes hypokinesia, motor impersistence, and inability to move one side of the body (see Chapter 11). Conceptual neglect is an inability to visualize the left-side of an imagined representation and can be considered a form of hemispatial neglect (discussed later). The examiner tests for conceptual neglect by asking patients to imagine themselves looking down from one end of a familiar corridor or street and describe what is on each side of the corridor or street. The examiner then repeats the task by asking the patients to imagine themselves looking down from the other end of the same corridor or street. Patients with conceptual neglect may fail to report structures on the left side of their visualization, which differs depending on which end of the corridor or street they imagine themselves to be.

Dressing Disorder or “Apraxia.” Spatial competence includes the ability to orient oneself in peripersonal, as well as extrapersonal or allocentric, space. The brain has different spatial maps and items within arms’ reach, particularly as they relate to the person’s egocentric frame of reference, can be disproportionately disturbed from right parietal lesions. One of the best ways to test this spatial map is “dressing apraxia.” Although not a real apraxia in the sense of a primary disturbance in motor programming, this name has persisted. Dressing “apraxia” is actually a dressing disorder from perispatial difficulty. Inquire whether the patient has difficulty dressing, such as correctly getting a limb through a sleeve or pant leg, or has sequential difficulty in dressing, such as putting on undergarments over street clothes. On testing, the examiner asks the patient to put on a coat several times; the examiner may provide a lab coat for testing. First, the examiner or caregiver holds the coat in an open manner with the inside facing the patient. Second, the patient must remove the hanging coat and put it on by themselves without orientation clues. In the third and fourth condition, one or both of the sleeves are inside-out. The examiner observes whether the patient gets muddled in attempting to put on the garment, inserting a limb into the wrong area, and orienting the garment incorrectly (body-garment disorientation). In addition, patients with dementia often fail to match their clothes or dress in multiple layers.

Environmental Disorientation. Spatial competence includes the ability to orient oneself in extrapersonal, as well as peripersonal, space. Patients with environmental disorientation cannot find their way in familiar and novel environments. Environmental disorientation may result from inability to form a mental map of the spatial relationships of a route (topographic disorientation) or from inability to recognize the spatial value of landmarks (topographagnosia).

In topographic disorientation, patients can recognize landmarks, but they cannot describe the route, trace or draw it (or make a floor plan), or read maps (planotopokinesia). These patients cannot find their way because they do not know how to orient themselves in relation to landmarks on a route. There are three main types of topographic disorientation: egocentric disorientation, heading disorientation, and anterograde disorientation. In egocentric disorientation, there are deficits in representing the relative location of objects with respect to self from dysfunction of the right parietal region. In heading disorientation, there is inability to derive directional information from landmarks from retrospenial or posterior cingulate lesions, especially on the right. In antegrade disorientation, there is inability to make new maps or encode information about spatial relationships, with possible loss of familiarity for old routes, from right parahippocampal dysfunction.

Classic topographagnosia is a ventral stream, category-specific visual agnosia similar to prosopagnosia. Topographagnosia is an inability to recognize salient environmental stimuli, such as buildings, as markers of a route (agnosia for landmarks). It is included here rather than with the agnosias because it is a disorder of environmental disorientation. These patients can distinguish different classes of buildings but cannot identify them as specific orienting landmarks. In topographagnosia, patients can describe the route, trace or draw it (or make a floor plan), and normally read a map. These patients may have bilateral or right-sided lesions in the medial occipital lobe involving the anterior lingual sulcus or the parahippocampal place area.

Testing for environmental orientation can include 1) orienting to a new route and its landmarks; 2) describing a familiar route and its landmarks; 3) tracing or drawing the route or a floor plan; and 4) reading a map. First, the examiner or caregiver guides the patient around a route (clinic or hospital if in-person) pointing out at least 10 landmarks along the way. The examiner instructs the patient to remember the walking route, as well as the indicated landmarks. Subsequently, after returning back to the starting point, the examiner asks the patient to guide the examiner along the same route, pointing out the previously indicated landmarks. The examiner measures the necessity for route cues and redirection and the recall of landmarks en route. Second, the examiner asks the patient to recall a familiar local route known to the examiner as well, for example, a common route to a known location or landmark. The patient must identify key intersections, roads, or buildings along the route and the correct direction from them. Third, the examiner asks the patient to draw a schematic of either the local route or the familiar route. The patient must trace one of the routes, including labeling of the landmarks or street names on the drawing. Finally, since personal topographic competence may be intact in a patient who cannot localize cities on a map, the examiner also asks the patient to read a two-dimensional map. It can be a standard road map, or one created by the examiner of the clinic, hospital, or local area. The examiner asks the patient to imagine traveling a designated route and to trace it on the map. Alternatively, planotopokinesia may be tested by asking the patient to place major cities or landmarks on a familiar map.

Balint Syndrome. The mental status examiner evaluates for the three features of Balint syndrome: dorsal simultanagnosia, optic ataxia, and oculomotor apraxia. Dorsal simultanagnosia is the inability to perceive the presence of more than one visual object or area at a time, which is distinct from ventral simultanagnosia in which everything is perceived but not integrated into a whole scene. The examiner asks the patient to look at a picture or drawing of a complex scene, such as Fig. 10.7 or the Cookie Theft Picture, and notes whether the patient reports only isolated items or segments of items in the picture. Further testing can involve drawing two adjacent circles and noting whether the patient only reports seeing one, then connecting the two circles with a “linker” that makes them glasses or a bicycle and noting whether the patient now sees the whole image ( Fig. 10.12 ). Oculomotor apraxia is the inability to voluntarily direct one’s gaze to a particular point. For testing, the patient is seated 50 to 60 cm or approximately 2 feet from the examiner and focuses gaze on the examiner’s nose. First, the examiner asks the patients to move their gaze to moving targets in each quadrant while maintaining their head straight. Second, they ask the patients to move their gaze to stationary targets in each quadrant again without moving their heads. The patients must quickly move their gaze directly to the targets in the peripheral field without evidence of undershooting, overshooting, or searching, and the maximum score is 8. A delay in the onset of eye movement on command may be the most sensitive indicator of oculomotor apraxia. Optic ataxia is the inability to voluntarily direct one’s hand movements toward visually presented targets. In a similar set-up as for oculomotor apraxia, the examiner asks the patients to use the right hand to touch a moving target in each peripheral quadrant while maintaining their gaze on the examiner’s nose. This is repeated with stationary targets and with the left hand. The patients must quickly reach out and touch the object without undershooting, overshooting, or searching movements. Scoring for the hand-eye coordination: 0 = total miss; 1 = near miss; 2 = accurate, with a maximum score of 16.

When needed, many other specialized tests can assess spatial abilities. These include tasks of discrimination of line orientation, contrast sensitivity and spatial frequency, mental spatial rotation (mentally rotate and visualize geometric shapes), motion detection (kinetopsia), and depth perception (relative size, interposition, perspective, texture gradient, motion parallax).