Journal of Neuropsychology (2013)

© 2013 The British Psychological Society

www.wileyonlinelibrary.com

Research paper

Where Am I? A new case of developmentaltopographical disorientation

Filippo Bianchini1,2, Liana Palermo1,2, Laura Piccardi1,3,Chiara Incoccia1, Federico Nemmi1,2, Umberto Sabatini1 andCecilia Guariglia1,2*1Dipartimento Psicologia 39, Sapienza Universit�a di Roma, Italy2I.R.C.C.S. Fondazione Santa Lucia, Rome, Italy3Dipartimento di Scienze della Salute, Universit�a degli Studi di L’Aquila, Coppito 2

(AQ), Italy

Recently, developmental topographical disorientation (DTD) was described (Bianchini

et al., 2010, J Clin Exp Neuropsychol, 20, 807–27; Iaria & Barton, 2010, Exp Brain Res, 206,

189–96; Iaria, Bogod, Fox, & Barton, 2009, Neuropsychologia, 47, 30–40) as a navigationaldeficit in the absence of neurological or psychiatric disorders. Here, we reported the case

of a healthy subject who presented this disorder. Dr.WAI was a 29-year-old right-handed

manwith normal development andnoclinical historyof neurological or psychiatric diseases

whowas affected by a very pervasive topographical orientation andnavigational disorder.A

neuroradiological exam confirmed the absence of structural and anatomical alterations of

the brain.Dr.WAIwas submitted to an extensive neuropsychological examination and to a

battery of tests specifically developed to assess developmental topographical disorder.

Using this battery, we analysed Dr. WAI’s acquisition of navigational information and re-

orientation processes. He showed severe DTD accompanied by deficits of different

cognitive processes directly or indirectly involved in navigational skills. Dr.WAI showed a

deficit in developing cognitive maps, already found in previous cases, plus difficulties in

evaluating distances and computingmetric environmental features.He represents a further

confirmation of the existence of DTD suggesting dissociations within the disorder related

to the level of development of the ability to build cognitive maps and the association of

different imagery deficits. Dr. WAI can help in shedding some light on the mechanisms

underlying lack of development of navigational skills.

Human spatial navigation includes abilities such as wayfinding in complex environments,

perceiving distances, and directional relationships,mentally transforming landmarkswithrespect to their position or orientation in space, planning routes to distant locations,

*Correspondence should be addressed to Cecilia Guariglia, Dipartimento di Psicologia, Sapienza Universit�a di Roma, Via deiMarsi, 78, Rome 00185, Italy (e-mail: cecilia.guariglia@uniroma1.it).

DOI:10.1111/jnp.12007

1

returning to the starting point after a long walk in a novel environment (Lawton, 2010;

Wolbers & Hegarty, 2010). Humans present a large variability in navigational abilities,

concerning the precision with which spatial information is encoded from sensory

experiences, the ability to form spatial representations of external environments and theefficacy in using them to guide navigational behaviour. Levels of different navigational

skills are not independent and interact, contributing to obtain good performances in

navigational tasks (for a review see Wolbers & Hegarty, 2010).

Inhealthy children, navigational competencies develop gradually and at distinct points

in time (Siegel &White, 1975; Lehnung et al., 2003). By the age of 6–9 months, children

find their bearings in the environment using only egocentric strategies (see, Acredolo,

1978; Hermer & Spelke, 1994). At 11 months they use information about landmarks and

landmark arrays (Acredolo, 1978; Acredolo & Evans, 1980). Between 18 and 24 months,toddlers are able to find hidden objects by using both navigational strategies (Hermer and

Spelke, 1994; Hermer & Spelke, 1996; Newcombe et al., 1998). The cognitive mapping

knowledge develops later and it is not fully functioning until the age of 10 years (Lehnung

et al., 1998; 2003).

Wang and Spelke’s (2002) proposed a theoretical distinction among three cognitive

processes subserving topographical orientation, which humans share with other species

(1) path integration, which is a process that operates by dynamic updating subject’s

location according to her/his movements in the environment; (2) view-dependent placerecognition, a process based on place and landmark recognition that matches viewpoint-

dependent representations of landmarks; (3) re-orientation, which operates by congru-

ence-finding on representations of the shape of the environment. Some capabilities to rely

on these processes are already present in very young children (18–24 months old; Hermer

& Spelke, 1996) who are still unable to fully develop cognitive maps.

Siegel and White (1975) proposed a theoretical model of environmental knowledge

that considers three different levels in acquiring spatial information: landmark knowl-

edge, route knowledge, and survey knowledge. At level of landmark knowledge,

individuals possess the ability to perceptually discriminate and recognize landmarks, but

are unable to derive from them any directional information (where a landmark is, which is

its relation with the environment andwith other landmarks). At level of route knowledge

directional information based on egocentric representation are added to landmark

knowledge allowing individuals to navigate by following directional instructions linking

consecutive landmarks (turn left at this landmark to reach the next one). The survey

knowledge consists in a mental map representation of the environment, based on an

allocentric frame of reference.When a brain disease impairs navigational abilities, patients often experience

devastating effects on their everyday lives. Specifically, topographical disorientation is

generally considered a consequence of acquired focal brain damages, dementia, and

congenital brain malformations (Barrash, 1998; Iaria et al., 2005; Pai & Jacobs, 2004) and

is characterized by selective loss of the ability to navigate in new or well-known

environments (Maguire, Burke, Phillips, & Staunton, 1996). Recently, a developmental

type of topographical disorientation (DTD) has also been described (Bianchini et al.,

2010; Iaria et al., 2009). DTD is a selective disorder of topographical orientation andnavigation in people who have no cerebral damage or perinatal problems. Since, there is,

until now, an unknown factor that affects the brain’s ability to receive and process

navigational information causing DTD, authors placed this disorder in the category of

selective developmental disorders, which includes dyslexia, developmental prosopoagn-

osia and selective language delay. Also in these disorders as in DTD, patients showed a

2 Filippo Bianchini et al.

normal intelligence without brain damage or other clear factors that could explain the

disorder in itself. Patients with DTD normally developed other cognitive abilities, but

complained a specific topographical deficit pervasive throughout the lifespan (see

Bianchini et al., 2010 and Iaria et al., 2009). The first reported case (Iaria et al., 2009)wasa 43-year-old woman (Pt1) who had no brain injury or psychiatric disease, but showed

persistent difficulty in topographical orientation. Subsequently, Bianchini et al. (2010)

described a 22-year-old man (F.G.) who showed a more pervasive disorder including

almost all processes involved in topographical knowledge and environmental navigation.

Specifically, Pt1 had a severe deficit in the formation of the mental map of the

environment; however, once she had acquired such a map through overtraining, her

performance on the retrieval task was similar to that of a control group. According to Iaria

et al. (2009) these findings point to an impairment specific to the acquisition rather thanthe retrieval and use of amental representation of the environment. Furthermore, shewas

able to develop successfully verbal scripts that helped her in orienteering in route-based

navigation tasks. She has also developed the ability to segregate and identify landmarks in a

landscape. Differently, F.G., the case described by Bianchini et al. (2010), showed amore

pervasive and severe topographical disorientation. Indeed, he was unable to learn the

path shown by the examiner in the route-based navigation task as well as to follow a path

shown on amap, showing also a deficit in translating the visual–spatial information of the

maps into verbal scripts. F.G. used the verbal scripts only when someone else providesthem. He failed in segregating and identifying a landmark in a landscape, and even when

he recognized a landmark he did not know its location or the directional information he

could derive from it.

More recently, Iaria and Barton (2010) reported a consistent number of individuals

who showed deficits in navigation and the ability to orient themselves in the

environment in an online evaluation in which participants performed nine tests (object

recognition; face identity, and expression recognition; landmark recognition; heading

orientation; left/right orientation (no landmarks); path reversed (no landmarks;formation and use of a cognitive map) including recognition of face, objects, and

landmarks as well as navigation tasks in virtual environments. This study confirmed that

DTD is not rare and suggests that its incidence could be comparable to that of other

selective developmental disorders, such as developmental prosopagnosia. Although, the

online assessment did not permit a thorough analysis of the cognitive components of

DTD, the study provides a large sample in which many different orientation strategies are

affected. Specifically, they found that people affected by DTD differ from matched

healthy controls only in those skills confined to the orientation/navigation domain,among which the ability to form a cognitive map was the most significant factor

distinguishing a person with DTD from one without DTD.

Here, we present another case of DTD in a healthy subject who was submitted to an

extensive evaluation aimed at clarifying the nature of his disorder. To preserve the

subject’s anonymity, we call him Dr. WAI, which is an acronym derived from “Where Am

I?”. Dr.WAIwas a 29-year-old right-handedmanwith normal development and no clinical

history of neurological or psychiatric disorders. Hewas submitted to an extensive battery,

that is, the DDTDB (DiViNa Developmental Topographical Disorientation Battery)consisting of navigational tasks and neuropsychological tests to analyse the nature of his

topographical disorientation. Analysis of Dr. WAI’s performance confirmed the presence

of pervasive DTD, but with characteristics that differed somewhat from those of

previously described cases. Dr. WAI increases our knowledge of this recently described

disorder, throwing some light on the mechanisms underlying lack of development of

Developmental topographical disorientation 3

navigational skills. Indeed, this case adds to the literature the suggestion that not onlyDTD

exists, but different types of it might be observed depending on the level of development

of the ability to build cognitivemaps and the association of different imagery deficits. This

could represent the first step for reasoning about the need of a taxonomy for DTD thatcould be different from those existing for acquired topographical disorders.

Case Report

Dr.WAIwas a 29-year-old, right-handedman (Salmaso&Longoni, 1985). Hehad aMaster’s

degree and during the period of the DDTDB evaluation he was enrolled in a Ph.D.programme. Dr. WAI was normal at birth and had no perinatal complications;

furthermore, his clinical history showed no motor, neurological or cognitive develop-

mental delays or neurological or psychiatric diseases.

Dr. WAI contacted the Neuropsychological Unit of the IRCCS Fondazione Santa Lucia

in Rome after reading an announcement to recruit individuals with navigational disorders

at University, during the spring of 2009. At the first appointment, he had reported

difficulty in finding his way in familiar places and in learning new routes in the

environment. He said that he never knewwhich direction to take to arrive at his office andthat he always had doubts when he went towards the centre of town or in the opposite

direction. Furthermore, he only realized his errors when he reached the edge of the city

and the ring road (GRA in Rome) because hewas unable to calculate the distance between

one known landmark and another.

He reported that when he went out with friends they never wanted him to drive

because he often lost his way. He suffered because of this and felt under pressure to

choose the right route. But,when he came to an intersection hewas uncertainwhether he

should go left or right. When we interviewed his colleagues, they confirmed that Dr. WAIwas unable to orient himself in the environment. Indeed, for several months after he

started the Ph.D. programme, Dr. WAI was able to go from one wing of the institute

(where the Ph.D. courses were held) to another wing only if someone accompanied him

because he systematically had difficulty finding the correct route when he was alone. Dr.

WAI said that he used an external electronic aid (a GPS navigator) to orient himself,

especiallywhen hewas notwith his girlfriend.When hewaswith her, she gave him verbal

indications.

We decided to investigate Dr. WAI’s navigational abilities by assessing the differentcognitive processes and strategies involved in topographical orientation. For this

purpose, we submitted him to a neuroradiological examination (MRI), a neuropsycho-

logical assessment, which included tests of general cognitive functioning, memory, and

a comprehensive evaluation of his ability to navigate by means of DDTDB, which

was specifically developed to assess DTD (derived from Bianchini et al., 2010). We

obtained written informed consent from Dr. WAI and approval from the local ethics

committee.

Methods

Neuroradiological exam

Magnetic Resonance imaging (MRI) was performed on a scanner (Allegra; Siemens

Medical Solutions, Erlangen, Germany) operating at 3.0 T, with a maximum gradient

strength of 40 mT/m, using a standard quadrature birdcage head coil for both RF

4 Filippo Bianchini et al.

transmission and RF reception. The protocol included axial, coronal, and sagittal T2-

weighted turbo spin-echo sequences (TR = 3,500 ms, TE = 354 ms), axial fluid-attenu-

ated inversion recovery (FLAIR) sequences (TR = 8,500, TE = 109, inversion time = 200)

covering the whole brain. We obtained 22, 5 mm gapless sections and a 256 9 256matrix using all available MR imaging techniques. The axial and coronal sections ran,

respectively, parallel and perpendicular to a line joining the anterior and posterior

commissures (AC–PC line). Whole-brain T1-weighted images were also obtained in the

sagittal plane using a modified driven equilibrium Fourier transform sequence (TE/

TR = 2.4/7.92 ms, flip angle 15°, voxel-size 1 mm 9 1 mm 9 1 mm). Two neuroradi-

ologists assessed all of Dr. WAI’s images.

His MRI examinations revealed homogeneous signal intensity of the cerebral

parenchyma, with no focal abnormality in either grey or white matter. His cortex wasof normal thickness with regular sulcation and gyration. His corpus callosum was of

normal thickness and presented regular morphology and homogeneous signal intensity.

His ventricular system was normal in size and symmetrical at the midline. The sub-

arachnoid spaces were regular. Both hippocampi were normal in morphology and size,

with a regular profile and signal intensity. Overall, the MRI examination presented a

completely normal picture (see Figure 1).

Neuropsychological assessment

During the entire evaluation, Dr. WAI was motivated and cooperative. His language

production and comprehension were normal. Furthermore, his Intelligence Quotient,

evaluated by means of the WAIS-R (Italian Version; Laicardi & Orsini, 1997), was within

the normal range (Total IQ = 123) and with a significant 25-point difference between

Verbal IQ (132) and Performance IQ (107) (see Table 1). Dr. WAI’s short-term and long-

term memory abilities on visuospatial and verbal tests (Carlesimo et al., 1996, 1996;

Spinnler & Tognoni, 1987) were within the normal range (see Table 1).

Figure 1. Four axial (upper panel) and four coronal (lower panel) slices of Dr.WAI’s structural MP

RAGE showing medial temporal lobe structures. Two magnified images of the hippocampus proper in a

coronal view are shown. MTL structures and hippocampus, as confirmed by an experienced

neuroradiologist, show the absence of any acquired or congenital brain damage.

Developmental topographical disorientation 5

Table 1. Results of the neuropsychological assessment that included tests standardized for use with

Italian-speaking patients. For tests lacking standardization data (*) we recruited controls matched for age,

gender, and years of education. Performances below the cut-off are in bold

Test DR.WAI Score Cut-off

General intelligence

Wechsler adult intelligence Scale–Revised (Laicardi & Orsini, 1997)

Full scale IQ 123 <75Verbal IQ 132 <75Information 17 4

Digit span 9 4

Vocabulary 18 4

Arithmetic 14 4

Comprehension 17 4

Similarities 14 4

Performance IQ 107 <75Picture completion 10 4

Picture arrangement 10 4

Block design 12 4

Object assembly 12 4

Digit symbol 11 4

Memory

Verbal memory

Rey’s 15 word learning task (Carlesimo et al., 1996)

Immediate recall 65/75 40.12/75

15 min delayed recall 15/15 8.28/15

Spatial memory

Rey’s complex figure (Carlesimo et al., 2002)

Copy 36/36 27.36/36

30 s delayed recall 24/36 14.21/36

20 min delayed recall 22/36 14.33/36

Oblivion 2 >4.25Corsi Block Test (Spinnler & Tognoni, 1987)

Span 4/9 Mean = 5.28; SD = 0.88 (t = �1.437; p = n.s.)

*Supra-span (n.cubes) 130/144 Mean = 132.40; SD = 7.13 (t = 0.307; p = n.s.)

*Supra-span recall (n.cubes) 8/8 Mean = 8.00; SD = 0.00 (t = 0.00; p = n.s.)

Visual-perceptual abilities

VOSP (Warrington & James, 1991)

Object perception

Screening test 20/20 15/20

Incomplete letters 20/20 17/20

Silhouettes 22/30 16/30

Object decision 16/20 15/20

Progressive silhouettes 9/20 >14/20Space perception

Dot counting 10/10 8/10

Position discrimination 20/20 18/20

Number location 8/10 7/10

Cube analysis 11/10 6/10

Benton’s facial recognition

test (Benton et al., 1975)

47/54 40/54

6 Filippo Bianchini et al.

Navigational skills assessment

Processes of acquisition of navigational information and re-orientationwere assessedwith

the DDTDB, derived from tests used by Bianchini et al. (2010) in a previous study of DTD,

based on theoretical models of normal development and normal navigation stages (Siegel&White, 1975; Wang & Spelke, 2002). The battery included three different categories of

tasks. The first category assessed specific domains such as visual spatial perception,

visuospatial memory and visuospatial imagery (see Table 2). The second and third

categories of tests assessed specific navigational abilities, respectively, in an experimental

and an ecological environment (see Table 2).

Dr. WAI’s performance on tests lacking standardization data was compared with that

of male volunteers (C) matched for age and years; the number of C varied from 20 to 5 in

different tests. Dr.WAI’s and controls’ performanceswere compared bymeans of analysisdeveloped by Crawford and Howell (1998; CH), using the computer program

SINGLIMS.EXE. This analysis uses a modified t test described by Sokal and Rohlf (1995)

and is themore suitable analysis to estimate the abnormality of the individual scoreswhen

the normative sample is small (that is less than 50 subjects).

Results for each test (as well as size of C group) are described below and shown in

Table 2.

Visuospatial perception, memory, and imagery evaluation

Assessment of Dr. WAI’s basic visuospatial abilities included tests of visuospatial

perception (Visual Object Spatial Perception Battery, Benton’s Facial Recognition Test),

visuospatial memory (Corsi Block Tapping Test: Span and Supraspan), and visuospatial

imagery (Memory of buildings, Letter Inspection Test,Mental Rotation Test, Generation of

imagery from long-term memory as Map drawing of current home) (see Tables 1 and 2).

Only tests not commonly used in clinical practice are described below.

On the Corsi Block Tapping Test (CBT; Corsi, 1972), Dr. WAI had a normal span, aswell as normal Supra-span learning and delayed recallwhen comparedwith a group of five

controls. His performance in object and space perception (Visual Object Spatial

Perception Battery, Warrington & James, 1991) and face recognition (Benton’s Facial

Recognition Test, Benton, VanAllen, Hamsher, & Levin, 1975)waswellwithin the normal

range (see Table 1).

Topographical abilities involve some specific aspects of cognition, such as

recognizing landmarks and scenes and describing and drawing a map of a familiar

environment, which rely on visual imagery abilities (Farah, 1989; Riddoch & Humph-reys, 1989). As in Bianchini et al.’s (2010) study, we referred to Kosslyn’s model (2005)

in Dr. WAI’s assessment, to evaluate processes of generation, inspection, and

transformation of visual mental images. We used Buildings Task (a modified version of

Nori & Giusberti, 2006; described in Palermo, Piccardi, Nori, Giusberti, & Guariglia,

2010) for evaluating the ability to generate a visual mental image from short-term

memory. Dr. WAI was asked to close his eyes and generate the mental image of the

picture of a building he had inspected for 10 s.Whenhewas ready, he had to identify the

picture among three other pictures of similar buildings. The task included 20 items. Hecorrectly identified 19 of 20 stimuli (see Table 2). The ability to generate an image from

long-term memory was assessed by asking the subject to draw a map of his actual and

childhood home. Dr. WAI was able to draw a map of his present home; but, he was

unable to draw a map of his childhood home in which he lived for 15 years. Even after

Developmental topographical disorientation 7

Table 2. Dr WAI’s and average controls’ performances in the navigational skills assessment.

Performances below the cut-off or insufficient are in bold

Test DR.WAI Score Controls

Visual imagery testing

Buildings task

(Palermo et al., 2010)

19/20 Mean = 19.5 (SD = 0.89); t = �0.55; p = n.s.

Letter inspection test

(Nori et al., in press)

16/20 Mean = 19.6 (SD = 0.82); t = �4.28; p < .0005

Mental rotation test

(Palermo et al., 2010)

13/20 Mean = 18.1 (SD = 2.47); t = �2.01; p = .03

Generation of imagery from long-term memory

Map drawing of

actual home

Plausible

Map drawing of

childhood home

Implausible

(Three trials

before

achievement)

Navigational abilities in experimental environments

Walking Corsi test (Piccardi et al., 2008)

Span (n. squares) 4/9 Mean = 4.60 (SD = 0.55); CH: t = �0.996; p = n.s.

Supraspan (n. squares) 133/144 Mean = 134 (SD = 6.71); CH: t = 0.136; p = n.s.

Supraspan recall

(n. squares)

8/8 Mean = 8.00 (SD = 0.00); CH: t = 0.000; p = n.s.

Road map test

(Money et al., 1965)

30/32 Mean = 30.47 (SD = 2.58); CH: t = �0.18; p = n.s.

The human version of Morris test (Guariglia et al., 2005)

Searching 594 s Mean = 150.14 (SD = 183.00); CH: t = 2.372; p = 0.013

Immediate reaching

(A + B + C)

223 s Mean = 415.32 (SD = 217.51); CH: t = �0.865; p = n.s.

Delayed reaching 15 s Mean = 72.00 (SD = 139.61); CH: t = �0.399; p = n.s.

The human version of Morris test WL (Nico et al., 2008)

Searching 39 s Mean = 65.64 (SD = 54.33); CH: t = �0.481; p = n.s.

Immediate reaching

(A + B + C)

1,491 s Mean = 115.08 (SD = 77.98); CH: t = 17.302;

p < .0001

Delayed reaching 24 s Mean = 9.76 (SD = 3.61); CH: t = 3.868; p = .0001

Semmes test

(Semmes et al., 1955)

3/5 Mean = 4.30 (SD = 0.84); CH: t = �1.482 p = n.s

Navigational abilities in virtual environment

CMT (Iaria et al., 2007)

Learning task 540 s Mean = 575.29 (SD = 199.06); CH: t = �0.29; p = n.s.

Retrieval task 659 s Mean = 298.35 (SD = 112.58); CH: t = 2.25; p < .05

Navigational abilities in ecological environments

Real ambient drawing

(cognitive map)

7/20 Mean = 17.50 (SD = 2.64); CH: t = �3.79; p = .002

Landmark recognition 10/16 Mean = 12.38 (SD = 3.29); CH: t = 0.682; p = n.s.

Route strategy 4/6 Mean = 5.86 (SD = 0.38); CH: t = �4.579; p = .018

Map strategy 3/4 Mean = 3.75 (SD = 0.71); CH: t = �0.99; p = n.s.

Verbal strategy –

CH: Crawford and Howell (1998) analysis.

8 Filippo Bianchini et al.

three attempts, his drawing was very implausible (see Figure 2). Only in the fourth

attempt and after a lot of time Dr. WAI has succeeded in realizing a correct drawing.

We assessed the ability to inspect a visualmental imageusing the Letter InspectionTest

(Nori, Piccardi, Palermo, Guariglia, & Giusberti, in press). Dr WAI was asked to imagine alowercase letter of the Latin alphabet printed on a sheet of a ruled notebook and to inspect

the image to determine whether the letter fit between the two lines or whether parts of

the letter extended beyond the upper or lower line (i.e., ‘Imagine writing the letter “d” in

lower case. Does the “d” occupy one or two rows?’). In the training session, hewas shown

the size of the ruled sheet and the letters. The task included 20 items (score range was 0–20). Dr. WAI’s performance was significantly worse than that of controls as shown in

Table 2. The ability to transform amental imagewas assessed bymeans ofMental Rotation

Test (based on Thurstone’s primary mental ability test cards; Thurstone, 1937; describedin Palermo et al., 2010). Dr.WAIwas asked to choose the figures that corresponded to the

target when mentally rotated from five alternatives. The task included 20 items. Also in

this test, Dr. WAI performed worse than controls (see Table 2).

Navigational abilities in experimental environments

To assess the ability to learn and remember spatial locations during navigation we used

Walking Corsi Test (WalCT: Piccardi et al., 2008). In WalCT, Dr. WAI had to reproduce apath shown by the examiner and to stop at different locations. Results showed that Dr.

WAI’s short-termmemory did not differ from that of controls. Both Dr.WAI’s learning and

delayed recall after 5 min were comparable to those of controls (see Table 2).

Dr. WAI was also asked to perform the human version of the Morris Water Maze Test

(Guariglia, Piccardi, Iaria, Nico, & Pizzamiglio, 2005; Nico et al., 2008) that required

memorizing and retrieving a target location in a rectangular room. The walls were

completely covered by curtains to mask the door, windows, and any feature that could be

(a) (b)

(c) (d)

Figure 2. Dr WAI’s consecutive attempts to draw his native home.

Developmental topographical disorientation 9

used as a reference point during navigation. Dr.WAI performed three tasks (1) searching:

starting from the centre of the room, he moved around until he reached the target point

signalled by awarning sound; (2) immediate reaching: he had to reach the target point by

following the shortest path and starting from the centre of the room in three differentpositions (0°, 90° and 270° of rotation with respect to the starting position during

searching); (3) delayed reaching: after a 30-min delay (spent in another room), he had to

reach the target point following the shortest path. Two different conditions were used,

each of which involved a different target location. In the first condition (without

landmark: Morris Test), no visual cue that could be used as a reference point or landmark

during navigation was present in the test room. In the second condition (with landmark:

Morris Test WL), two objects (a floor lamp and a hat stand) were placed at the centre of

two different walls opposite to the corner of the target location. In the condition withoutlandmarks, the immediate reaching task assessed the integrity of path integration when

Dr.WAI performed the task starting from a positionwith 0° of rotationwith respect of the

starting position of the searching task. Differently, the ability to reorient by means of

the geometric module was assessed when the same task was performed starting from the

positions with 90° and 270° of rotation. In the same condition, the delayed reaching task

evaluated the ability to develop simple cognitive maps representing only the shape of the

room and the target position. In the conditionwith landmarks, immediate reaching tested

the ability to use the configuration of the landmark, whereas delayed reaching assessedthe ability to develop more complex cognitive maps that included the position of the

landmarks in addition to the shape of the room and the position of the target location.

In both conditions, performance on the three tasks was video-recorded and the score

was the time spent on each task. In the searching condition of the Morris Test, Dr. WAI

needed more time than controls to reach the target point. A perusal of his video-recorded

performance showed that he searched for the target by following a concentric pattern that

started at the centre of the room and extended no more than 2 m from the walls; after

several attempts, however, he enlarged his searching area and found the target point. InImmediate Reaching, Dr. WAI’s performance was comparable to that of controls, that is,

with no difference in the use of path integration and re-orientation processes.

Analogously, in Delayed Reaching Dr. WAI’s performance did not differ from that of

controls (see Table 2 for Dr. WAI and CH analysis).

In the Morris Test, WL, the time Dr. WAI needed to reach the target point in the

Searching condition was comparable to that of controls. However, Dr. WAI was

significantly slower than controls in both Immediate Reaching and Delayed Reaching

after a 30-min delay (see Table 2 for Dr. WAI and CH analysis).Dr.WAIwas also asked to performRoadmap test (Money, Alexander, &Walzer, 1965)

in which he had to use a pen to track a path drawn on a map, while he imagined walking

along thepath. At each intersectionhehad to verbally indicatewhether hewas turning left

or right; the score was the number of correct indications. Again, as reported in Table 2,

Dr. WAI’s performance did not differ from that of controls. In the Map Reading test

(Semmes, Weinstein, Ghent, & Teuber, 1955), the task was to follow a path using a map,

but without rotating it. The map reproduced the 3 x 3 grid of red circles on the

grey carpet (1.5 x 1.5 m) on the floor. Five trials of increasing difficulty (number of turnsand rotations increase in successive trials) were administered. Dr. WAI was able

to reproduce the path by translating the allocentric coordinates into egocentric

coordinates (see Table 2).

Dr. WAI was also asked to perform Virtual reality test (CMT: Iaria, Chen, Guariglia,

Ptito, & Petrides, 2007), used also by Iaria et al. (2009) in Pt1. The CMT included two

10 Filippo Bianchini et al.

experimental tasks (1) a learning task, in whichDr.WAI had to explore a virtual city with

six landmarks and to create a mental representation of the city; and (2) a retrieval task in

which he had to use the mental representation of the city to reach a specific target

location. In the learning task,Dr.WAI took the same time as controls to generate themapof the city, but he needed more time to become oriented in the retrieval task (see

Table 2).

Navigational abilities in ecological environments

This section included five tasks of navigation and recognition of real landmarks that were

devised to assess specific navigational abilities in complex, real environments. The Real

environment drawing (cognitive map) in which, the examiner accompanied Dr. WAIalong a route in a hospital ward he had never explored before, and asked him tomemorize

the environment. Then, he had to draw a map of the hospital ward. Each drawing was

scored by giving one point for each room/hall correctly located and 0.5 points for each

room incorrectly locatedwith respect to the realmap (maximumscore: 20).Dr.WAI drew

a very poor map with few details (i.e., just seven elements) of the environment (see

Table 2 and Figure 3).

In the Landmark Recognition, Dr. WAI was shown photographs of 16 landmarks

encountered on the route in the previous task and 16 distracters and was asked torecognize the landmarks. Dr. WAI’s performance did not differ from that of controls (see

Table 2). In the Route Strategy, Dr. WAI had to retrace a route with six turns he had just

Figure 3. Real environment drawing:On the left the real map of the hospital ward. The line indicates the

pathway along which the examiner accompanied the participant (from the hall to the room with pictures

and vice versa). On the right the drawing of the ward by Dr WAI.

Developmental topographical disorientation 11

performed by following the examiner. Scores were the number of correct turns and the

length (in meters) of the performed route. Dr. WAI missed the last two turns and decided

that he had already reached the final point (see Figure 4a). Dr. WAI’s number of turns

significantly differed from those of controls (see Table 2) and he failed to recognize thatthe final point could not be on the main street, but was in a parking lot in front of a

solarium.He actually stopped in front of a signboard indicating the solarium, located at the

corner between the main street and the parking lot. Dr. WAI followed a significantly

shorter route than the controls. In Map Strategy, he was required to follow a route (with

four turns) depicted on amap of an unfamiliar neighbourhood. The scorewas the number

(a) (b)

Figure 4. (a) Route strategy task: The drawing represents the path followed by the examiner (red line)

and the reproduction of the same path by DrWAI (blue line). Squares indicate the points where DrWAI

stopped. (b) Map strategy task: The red line represents the path DrWAI was supposed to follow and the

blue line the path DrWAI actually followed. The arrow and the target represent, respectively, his points

of departure and arrival.

Figure 5. Verbal strategy task:On the left, the dotted line represents the path to be followed byDrWAI

and the full line the path that Dr WAI actually performed; the grey line indicates the path that Dr WAI

performed to go back to the previous start point. The black arrow and the black target represent,

respectively, the start and the arrive performed for verbal information, whereas the grey arrow and the

grey target represent the start and the arrive performed to go back to the start point. The circle highlights

the area where Dr. WAI stopped after the third turn and asked the examiner for directions because he

had lost his way. On the right are the instructions for the subject.

12 Filippo Bianchini et al.

of correct turns. When asked to perform the depicted pathway, Dr. WAI’s performance

(see Figure 4b) was not different from that of controls (see Table 2).

In the Verbal Strategy, Dr. WAI had to follow a new route in the hospital using written

instructions describing landmarks and direction (right/left) to take at each turning point.In this task, Dr. WAI stopped after the third turn and asked the examiner for directions

because he had lost his way (see Figure 5) stating he has already walked for a long time

without finding the next landmark. None of the 20 controls had any difficulty on this task.

In summary, Dr. WAI’s performance was clearly defective on some of the mental

imagery tests (i.e., Inspection Test, Mental Rotation Test, and Map drawing of childhood

home) that entailed retracing a previously travelled route and developing, storing, and

using cognitive maps of real environments (Real ambient drawing and Morris Test WL),

and in using cognitive maps of virtual environments.

Discussion

Dr. WAI showed a severe form of DTD in daily life. Unlike F.G. (Bianchini et al., 2010),

however, he had developed somenavigational skills (landmark strategy,map reading), but

had obvious difficulty in developing cognitive maps that extended beyond the generalgeometric features of the environment. He was able to use a map strategy only if he could

look at a paper map (map strategy, Semmes test), but was unable to develop a map based

on his own direct experience (Morris Test WL, Real environment drawing) or to

reproduce a route (Route strategy). Based on previously described cases, these

observations suggest that DTD is a complex syndrome involving different aspects of

navigational and topographical skills with different degrees of severity in different

subjects. Indeed, navigation being a complex ability subtended by several different skills,

it is very likely that a developmental disorder affects different individuals in different ways(e.g., involving different processes) andwith different degrees of severity. Caution should

be taken in describing DTD cases because individuals with low spatial skills and poor

sense of direction show significant low performances in forming a mental representation

of the environment (see, Thorndike & Golden, 1981; Kato & Takeuchi, 2003; Hegarty

et al., 2006; Nori & Giusberti, 2006; Pazzaglia & De Beni, 2001), suggesting that the

assessment of DTD has to be exhaustive in investigating navigational processes in the

environment. DTDbeing a developmental disorder, the possibilitymust also be taken into

account that different individuals develop different coping strategies to deal with theirorientation problems. Thus, it is theoretically possible that different behaviours we

observe are the results of differences in developed coping strategies, and not the results of

differences in the type of processes that are altered by DTD. For this reason, in studying

new cases of DTD it is very important to verify if they present differences in the

navigational processes involved in the disorder or just differences in the navigational

behaviour since the latter may be the result of compensatory strategies in individuals

affected by the same navigational alteration, even if at different degrees of severity.

One feature that might characterize different types of DTD is the presence ofnavigational memory deficits. Dr. WAI showed normal ability to learn and retrieve

sequential information in both peripersonal and navigational space. The presence of

normal long-termmemory in navigational space counters the results of our previous study

of F.G. who showed normal memory in peripersonal space and defective retrieval in

navigational space. This suggests that navigational memory deficits can differentiate

degree and characteristics of DTD in a future taxonomy also for developmental

topographical deficits. Furthermore, the existence of different types of DTD is also

Developmental topographical disorientation 13

supported by a direct comparison of Dr. WAI’s navigational behaviours with those of the

two previously described cases of DTD.

On the CMT, both F.G. and Pt1 had great difficulty in acquiring the map. By contrast,

Dr. WAI did not differ from controls in the learning phase, but was unable to use the maphe had learned for navigational purposes. Indeed, in real environments his test behaviour

differed from that of Pt1 and F.G. Specifically, like Pt1, but unlike F.G., Dr. WAI never

completely lost his way on tests assessing route strategy; but, unlike Pt1, he failed to reach

his goal. Like Pt1, but unlike F.G., Dr.WAIwas able to find hisway in themap strategy test,

and unlike both Pt1 and F.G., he lost his way when he had to follow verbal instructions.

Finally, like F.G., but unlike Pt1, Dr. WAI showed an abnormal difference between Verbal

IQ and Performance IQ, defective performance on themental rotation tests and omissions

and errors in locating items in the drawing of his own home, in addition to the scalingerrors also shown by Pt1.

Thus, it seems that the severity of Dr. WAI’s DTD fell between that of Pt1, who had

difficulty storing environmental information by transforming it into a cognitive map, and

that of F.G., who was completely unable to develop a cognitive map and was affected by

defective navigational memory. However, Dr. WAI’s DTD seemed to differ both

qualitatively and in terms of severity. Indeed, PT1 was reported to have ‘difficulty with

acquisition rather than retrieval of cognitive maps’ (Iaria et al., 2009 p. 39) and F.G. was

unable to developmaps. Thus, bothhaddeficits in the development of cognitivemaps.Dr.WAI seemed partially able to process cognitive maps because he learned the map of the

CMT normally and was able to develop a schematic map of the general shape of the

environment and the location of the target point in the Morris Water Maze without

landmarks. However, Dr. WAI was unable to develop a cognitive map when landmarks

were added to the Morris Maze or when the cognitive map had to be developed from real

navigation in a real environment. The apparent contradiction between performance on

the CMT and in real environments deserves to be discussed. In the learning task of the

CMT, a virtual city had to be explored and subjects had to place six landmarks in theircorrect positions on a paper map of the city. Thus, for at least two reasons learning in the

CMT is quite different from that in a real environment. First, when navigating in a virtual

environment subjects process only visual information (relative to optic flow, visuospatial

features, etc.), whereas in navigating in a real environment visual information has to be

integrated with vestibular information. Second, in the CMT the general features of the

environment (the shape of the city, streets and crossings, aswell as number, and shapes of

buildings) are already represented on the paper map on which subjects have to place the

six landmarks and do not need to be inferred during navigation. Thus, the development ofa cognitive map of the CMT city might be facilitated for both reasons.

Dr.WAI’s difficulty in developing complex cognitivemapswas similar to that observed

by Hermer and Spelke (1996) in young children. Children are able to develop schematic

cognitive maps in the real environment at 18 months of age (i.e., they are able to process

geometrical environmental features), but were unable to indicate the position of objects

and relevant visual cues on themaps. The ability to include landmarks in themaps appears

at around 4 1/2 years of age (Hermer & Spelke, 1996). On the basis of these data, we can

conclude that Dr. WAI’s ability to develop cognitive maps never developed beyond thelevel of an 18-month-old child.

In the light of Siegel andWhite’s (1975) model of human navigation development, we

can state that Dr.WAI never passed the route navigation level. Indeed, he recognized

landmarks, was able to describe their sequence along a route, and was able to direct his

navigation towards a visible landmark. But he had not completely acquired either the

14 Filippo Bianchini et al.

route phase or the survey phase and was able to navigate in familiar environments only

after over-learning the verbal directional labelling of landmarks. Failures could be ascribed

to errors in recalling directional labels (e.g., ‘at the post office turn right’ instead of ‘turn

left’) or to the inability to process metric information about the travelled route. Indeed,when giving or following verbal instructions to take a route, apart from the description of

the landmarks on turning points, information about the distance between landmarks has

an important role; indeed, it allows determining the correctness of the route, especially in

describing/estimating, and travelling distances between two landmarks (Denis, Pazzaglia,

Cornoldi, & Bertolo, 1999). In Dr. WAI’s case, a specific disorder in computing metric

environmental information was suggested from spontaneous descriptions of his difficulty

in the initial interview and from data derived from the neuropsychological assessment.

Indeed, his peculiar searching in the Morris Maze without landmarks suggested that Dr.WAI was unable to judge distances, indeed he failed to compute exact distance from the

walls failing in locating the target. Furthermore, he missed about 50 m in the Route Test

and in following the verbal instructions in the Verbal Strategy test he got lost after the

second turn because hewas unable to calculate the distanceheneeded to travel before the

next landmark and turning point. Difficulty in evaluating metric features was not limited

to environmental navigation, but also seemed to affect his performance on mental visual

imagery when hewas asked to judge whether a given letter of the alphabet would extend

beyond the lines of a ruled sheet of paper. Considering his difficulty in using metricproperties, it was evident that he never acquired the survey phase in which this kind of

ability is developed. According to Siegel and White’s model, F.G. was in the landmark

phase, Dr. WAI had only some rudimentary abilities in the route phase and Pt1 had only

some abilities in the survey phase. Taking into account all of the above results, we can

conclude that Dr. WAI’s DTD was characterized by two deficits, one in integrating visual

cues in a schematic cognitive map and one in computing metric environmental features

and walked distances.

Some final comments on Dr. WAI’s abilities are needed.Despite his inability to develop complex cognitive maps (i.e., maps not limited to the

general shape of the environment and a few target points) and in computing metric

distances, Dr. WAI showed normal ability on the Map reading Test (Semmes et al., 1955)

and on theMap-strategy test, suggesting that it is possible to learn how to translate graphic

allocentric representations into egocentric directions even when the ability to mentally

represent navigational information in an allocentric format is defective. This observation

suggests that it may be possible to train individuals with topographical disorientation and

DTD to use maps to compensate for their navigational difficulties, by teaching them totranslate the information on the map into verbal instructions.

In conclusion, this case of DTD not only increases our knowledge of this recently

described disorder but sheds some light on the mechanisms underlying lack of

development of navigational skills. Indeed, this case suggests that dissociations in

navigational abilities can be observed in the different cases affected by DTD related to the

level of development of the ability to build cognitive maps and the association of different

imagery deficits. In the first case of DTD (Pt1, Iaria et al., 2009), cognitive map

development was difficult and slow, but no mental imagery deficit was observed. In thesecond case (Bianchini et al., 2010), cognitive map development was impossible and a

deficit in transforming mental images and inability to process spatial relational

information severely affected the possibility of using route strategies. In this third case,

a deficit in placing landmarks on cognitive maps was present accompanied by a deficit in

processing the metric features of visuospatial stimuli that impedes the evaluation of

Developmental topographical disorientation 15

distances during navigation. This latter deficit severely affects the use of route strategies in

a subject who was able to recognize landmarks and know the sequence of landmarks

along familiar routes.

Concerning severity of the deficit, it is evident that the three individuals had differentlevels of difficulty in daily life: Pt1 showed the least severe deficit and F.G. themost severe

one. According to Iaria andBarton (2010) study, DTD seems to be a condition that affects a

significant number of people, who show clear impairments in a number of orientation

skills. Actually, it is still impossible to estimate the prevalence of DTD, but new evidence

can help to better define this condition as well as guideline for re-education.

Acknowledgements

We are thankful to NeuroLab (www.neurolab.ca) for providing CMT. The authors declare

they have no conflicts of interest or grants to declare.

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