Elisabetta Ladavas - Academia.edu (original) (raw)
Papers by Elisabetta Ladavas
Neuropsychologia, 1997
Nine patients with left-sided neglect and nine matched control patients performed three tasks on ... more Nine patients with left-sided neglect and nine matched control patients performed three tasks on horizontal (either normal or mirror-reversed) letter strings. The tasks were: reading aloud, making a lexical decision (word vs non-word), and making a semantic decision (living vs non-living item). Relative to controls, neglect patients performed very poorly in the reading task, whereas they performed nearly normally in the lexical and semantic tasks. This was considered to be a dissociation between direct tasks, rather than a dissociation between explicit and implicit knowledge. The explanation offered for the dissociation is in terms of both a dual-route model for reading aloud and a degraded representation of the letter string.
Brain, 1987
The hypothesis that right posterior parietal lesions cause two attentional deficits, namely, a re... more The hypothesis that right posterior parietal lesions cause two attentional deficits, namely, a reduced reactivity to stimuli in the left visual field (LVF), and a reduced reactivity to any stimulus which occupies a relative left position, was tested in 8 patients with an extinction syndrome. In Experiments 1 and 2 the first hypothesis was tested by measuring reaction times (RTs) to visual stimuli presented in the LVF and in the RVF, whereas the second hypothesis was tested by measuring RTs to stimuli totally positioned in the LVF, and in the RVF. The results showed that RTs to stimuli which occupied a relative left position were longer than RTs to stimuli which occupied a relative right position independent of the visual field stimulated and RTs to LVF stimuli were longer than RTs to RVF stimuli. Experiment 3 was designed to examine whether the attentional deficit associated with right parietal damage was mostly related to the use of gravitational rather than to retinal coordinates. In this experiment the patients tilted the head either to the left or the right by 90 deg and they responded to two stimuli displayed above and on either side of a fixation mark. The results showed that the difficulty in attending to the left was related both to the gravitational and the retinal frames of reference.
Cognitive Neuropsychology, 1994
The study concerned rehabilitation of spatial neglect by manipulation of spatial attention. The t... more The study concerned rehabilitation of spatial neglect by manipulation of spatial attention. The treatment was limited to the visual modality but extinction and neglect were tested in both visual and tactile modalities. The results showed a clear-cut improvement of visual neglect. Considering that the treatment was based exclusively on manipulating attention, this constitutes strong evidence in favour of the orienting
Journal of The International Neuropsychological Society, 1996
In this paper different models of anosognosia are confronted and data concerning denial behaviors... more In this paper different models of anosognosia are confronted and data concerning denial behaviors are presented that were collected on a selected population of right brain-damaged patients affected by motor and neglect disorders. Anosognosia for motor impairment and anosognosia for cognitive impairments were found to be dissociated, as well as anosognosia for the upper and lower limb motor impairments. These findings are then discussed in an attempt to choose the more suitable theoretical framework for interpreting the various disorders related to denial of illness.
Interpreting the behaviors of others crucially requires the ability to decode the observed kinema... more Interpreting the behaviors of others crucially requires the ability to decode the observed kinematic information into a causal relationship between the motor sequence and its outcome. It has been suggested that this ability depends on action 'simulation'mechanisms mapping observed motor acts onto corresponding motor programs and associated somatosensory consequences stored into the observer's action repertoire (Rizzolatti and Craighero, 2004; Wilson and Knoblich, 2005; Urgesi et al., 2010; Keysers et al., 2010; ...
The study of pathologic behavioral phenomena following damage to the central nervous system has s... more The study of pathologic behavioral phenomena following damage to the central nervous system has substantially contributed to our understanding of the normal organization of cognitive brain functions. The investigation of clinical extinction in neurological patients, for example, revealed that events occurring in the immediate proximity to the body (i.e. in near peripersonal space) undergo a high degree of multisensory processing.
Nature, 1997
Some patients with brain damage fail to identify a sensory stimulus presented on the opposite sid... more Some patients with brain damage fail to identify a sensory stimulus presented on the opposite side to their lesion (contralesional) when a competing stimulus is presented on the same side (ipsilesional) 1 . This phenomenon has become known as extinction. It is commonly ...
Restorative neurology and neuroscience, Jan 8, 2015
The aim of the study is to compare the effects of multiple sessions of cathodal (c-tDCS) or anoda... more The aim of the study is to compare the effects of multiple sessions of cathodal (c-tDCS) or anodal tDCS (a-tDCS) in modulating the beneficial effects of prism adaptation (PA) treatment in neglect patients. 30 neglect patients were submitted to 10 daily sessions of PA treatment. Patients were pseudo-randomly divided into 3 groups. In the c-tDCS-group, each PA session was coupled with 20 minutes of cathodal stimulation of the left, intact PPC; in the a-tDCS-group, anodal stimulation was applied to PPC of the damaged hemisphere; in the Sham group, sham stimulation was applied. Neglect was evaluated before and after treatment with the Behavioral Inattention Test. Combined tDCS-PA treatment induced stronger neglect improvement in the a-tDCS group as compared to the Sham group. No improvement was found in the c-tDCSgroup, with respect to that normally induced by PA and found in the Sham group. c-tDCS abolished neglect amelioration after PA, possibly because stimulation affected the sensor...
Brain and cognition, 2006
Deficits affecting Central Executive System (CES) of working memory (WM) are the main neuropsycho... more Deficits affecting Central Executive System (CES) of working memory (WM) are the main neuropsychological outcome after traumatic brain injury (TBI) and can also explain deficits in other domains, like divided attention, executive functions and long-term memory. For this reason we developed a rehabilitative program based on CES functions and we expected to find an improvement in WM as well as in those cognitive functions controlled by the CES. The experimental group was composed by 9 TBIs, selected for WM deficits, whereas the control group was composed by 6 TBIs, without WM deficits, but with speed processing deficits. All patients performed a cognitive training, based on PASAT (Gronwall & Wrightson, 1981)and two new versions of this task. The results showed in the experimental group an improvement in WM and in the cognitive functions controlled by the CES, whereas control patients did not show any improvement after the cognitive training.
Neuropsychologia, 1993
Based on a test introduced by Tegnér and Levander, Brain114, 1943–1951, 1991, right brain-damaged... more Based on a test introduced by Tegnér and Levander, Brain114, 1943–1951, 1991, right brain-damaged patients were assigned to a group with unilateral perceptual neglect and a group with directional motor neglect. Brain scans showed that all directional motor neglect patients had frontal lesions, whereas in perceptual neglect patients the frontal lobes were always spared. All patients were asked to execute two tasks, which were also administered to a control group. One task consisted in pointing to tokens symmetrically distributed on a display. The other task consisted in picking up the same tokens. The tasks were first executed with the aid of vision and then in a blindfolded condition. In the case of patients with perceptual neglect, performance on the left side was better in the pick-up task than in the pointing task and improved in the blindfolded condition. Neither patients with directional motor neglect nor control patients showed these effects. The results were explained in terms of the hyperattentional hypothesis of perceptual neglect, according to which, in this form of neglect, attention is captured by the objects that lie on the right side of space.
Social cognitive and affective neuroscience, 2015
Human body postures convey useful information for understanding others' emotions and intentio... more Human body postures convey useful information for understanding others' emotions and intentions. To investigate at which stage of visual processing emotional and movement-related information conveyed by bodies is discriminated, we examined event-related potentials elicited by laterally presented images of bodies with static postures and implied-motion body images with neutral, fearful or happy expressions. At the early stage of visual structural encoding (N190), we found a difference in the sensitivity of the two hemispheres to observed body postures. Specifically, the right hemisphere showed a N190 modulation both for the motion content (i.e. all the observed postures implying body movements elicited greater N190 amplitudes compared with static postures) and for the emotional content (i.e. fearful postures elicited the largest N190 amplitude), while the left hemisphere showed a modulation only for the motion content. In contrast, at a later stage of perceptual representation, r...
Neuropsychologia, 2006
Prism adaptation (PA) has been demonstrated to be effective in improving hemispatial neglect. How... more Prism adaptation (PA) has been demonstrated to be effective in improving hemispatial neglect. However not all patients seem to benefit from this procedure. Thus, the objective of the present work is to provide behavioural and neuroanatomical predictors of recovery by exploring the reorganization of low-order visuo-motor behaviour and high-order visuo-spatial representation induced by PA. To this end, 16 neglect patients (experimental group) were submitted to a PA treatment for 10 daily sessions. Neglect and oculo-motor responses were assessed before the treatment, 1 week, 1 and 3 months after the treatment. Eight control patients, who received general cognitive stimulation, were submitted to the same tests at the same time interval. The results showed that experimental patients obtained, as a consequence of PA, a long lasting neglect recovery, a reorganization of low-order visuo-motor behaviour during and after prism exposure (error reduction and after-effect, respectively) and a leftward deviation of oculo-motor responses. Importantly, the level of error reduction obtained in the first week of treatment was predictive of neglect recovery and the amelioration of oculo-motor responses, and the degree of eye movement deviation was positively related to neglect amelioration. Finally, the study of patients' neuroanatomical data showed that severe occipital lesions were associated with a lack of error reduction, poor neglect recovery and reduced oculo-motor system amelioration. In conclusion, the present results suggest that low-order visuo-motor reorganization induced by PA promotes a resetting of the oculo-motor system leading to an improvement in high-order visuo-spatial representation able to ameliorate neglect.
Neuropsychologia, 2010
Auditory and tactile stimuli are integrated within a limited space around the body to form an aud... more Auditory and tactile stimuli are integrated within a limited space around the body to form an auditory peripersonal space (APPS). Here we investigate whether the APPS representation around the hand can be extended through the use of a common technological tool such as the computer mouse. When using a mouse, an action occurring in the space around the hand has a distal effect in the space defined by the computer screen; thus, the mouse virtually links near and far space. Does prolonged experience with the mouse durably extend APPS representation to the far space? We examined 16 habitual mouse users to determine whether a sound presented near the right hand or near the computer screen affected reaction times to a tactile target at the hand. When subjects sat in front of the computer, without holding the mouse, they responded faster to tactile stimuli when sounds were presented near the hand rather than near the screen, consistent with a normal segregation of APPS around the hand. In c...
Neuropsychologia, 2010
Please cite this article in press as: Magosso, E., et al. Neural bases of peri-hand space plastic... more Please cite this article in press as: Magosso, E., et al. Neural bases of peri-hand space plasticity through tool-use: Insights from a combined computational-experimental approach. Neuropsychologia (2009),
NeuroReport, 1998
We infer the functional integration of the visual, auditory and proprioceptive spatial maps from ... more We infer the functional integration of the visual, auditory and proprioceptive spatial maps from the behaviour of a patient (G.A.) with left visual neglect, i.e. a derangement of visual space representation. G.A. was required to point manually to left, centre or right acoustic stimuli, under visual control or blindfolded, with the responding hand (left or right) located either on the left, centre or right space. G.A.'s manual pointing responses to left auditory stimuli were strongly influenced by the visual spatial information and by the proprioceptive spatial information related to the position of the responding effector. In the visual control condition, when the patient performed the task with the left effector located on the left, pointing responses to left auditory stimuli were shifted towards the right intact visual space. In contrast, when the visual spatial information was rendered less salient, i.e. in the blindfolded condition, and the effector was again located on the left, manual pointing responses were confined to the previously ignored left space. These findings are consistent with the view that the acoustic representation is modulated by the impaired visual representation and by the proprioceptive spatial map related to the position of the responding effector.
Neuropsychologia, 2001
There have been many studies of visuospatial neglect, but fewer studies of neglect in relation wi... more There have been many studies of visuospatial neglect, but fewer studies of neglect in relation with other sensory modalities. In the present study we investigate the performance of six right brain damaged (RBD) patients with left visual neglect and six RBD patients without neglect in an auditory spatial task. Previous work on sound localisation in neglect patients adopted measure of sound localisation based on directional motor responses (e.g., pointing to sounds) or judgement of sound position with respect to the body midline (auditory midline task). However, these measures might be influenced by non-auditory biases related with motor and egocentric components. Here we adopted a perceptual measure of sound localisation, consisting in a verbal judgement of the relative position (same or different) of two sequentially presented sounds. This task was performed in a visual and in a blindfolded condition. The results revealed that sound localisation performance of visuospatial neglect patients was severely impaired with respect to that of RBD controls, especially when sounds originated in contralesional hemispace. In such condition, neglect patients were always unable to discriminate the relative position of the two sounds. No difference in performance emerged as a function of the visual condition in either group. These results demonstrate a perceptual deficit of sound localisation in patients with visuospatial neglect, suggesting that the spatial deficits of these patients can arise multimodally for the same portion of external space.
Neuropsychologia, 2002
Possible auditory deficits in neglect were examined by comparing the performance of four right br... more Possible auditory deficits in neglect were examined by comparing the performance of four right brain-damaged (RBD) patients with left visuospatial neglect, versus four RBD patients without neglect, in three auditory tasks. The first task required speeded discrimination of sound elevation, by moving a central lever up or down according to the vertical position of a peripheral target sound, regardless of its side. The other two auditory tasks were non-spatial, requiring either speeded pitch discrimination (moving the central lever up for high pitch, down for low pitch) or speeded target detection. Neglect patients' performance was impaired with respect to RBD controls only when the auditory task required spatial coding of the target sound (the up/down spatial discrimination). This demonstrates a selective deficit of auditory space perception in neglect patients. This auditory spatial deficit was more pronounced for left than right sounds. Since auditory space perception was impaired in the 6ertical dimension, the observed deficit cannot be attributed to a systematic rightward shift in sound localisation. Instead, the results suggest increased spatial uncertainty in sound localisation by neglect patients, particularly for auditory targets on the contralesional side. These findings are related to multimodal coding of space in the parietal cortex, which was damaged in the neglect patients, but not in the RBD controls.
Trends in Cognitive Sciences, 2002
In order to code visual peripersonal space, human and non-human primates need an integrated syste... more In order to code visual peripersonal space, human and non-human primates need an integrated system that controls both visual and tactile inputs within peripersonal space around the face and the hand, based on visual experience of body parts. The existence of such a system in humans has been demonstrated, and there is evidence showing that visual peripersonal space relating to the hand has important dynamic properties, for example, it can be expanded and contracted depending on tool use. There is also evidence for a high degree of functional similarity between the characteristics of the visual peripersonal space in humans and in monkeys.
Trends in Cognitive Sciences, 2003
Neuropsychologia, 1997
Nine patients with left-sided neglect and nine matched control patients performed three tasks on ... more Nine patients with left-sided neglect and nine matched control patients performed three tasks on horizontal (either normal or mirror-reversed) letter strings. The tasks were: reading aloud, making a lexical decision (word vs non-word), and making a semantic decision (living vs non-living item). Relative to controls, neglect patients performed very poorly in the reading task, whereas they performed nearly normally in the lexical and semantic tasks. This was considered to be a dissociation between direct tasks, rather than a dissociation between explicit and implicit knowledge. The explanation offered for the dissociation is in terms of both a dual-route model for reading aloud and a degraded representation of the letter string.
Brain, 1987
The hypothesis that right posterior parietal lesions cause two attentional deficits, namely, a re... more The hypothesis that right posterior parietal lesions cause two attentional deficits, namely, a reduced reactivity to stimuli in the left visual field (LVF), and a reduced reactivity to any stimulus which occupies a relative left position, was tested in 8 patients with an extinction syndrome. In Experiments 1 and 2 the first hypothesis was tested by measuring reaction times (RTs) to visual stimuli presented in the LVF and in the RVF, whereas the second hypothesis was tested by measuring RTs to stimuli totally positioned in the LVF, and in the RVF. The results showed that RTs to stimuli which occupied a relative left position were longer than RTs to stimuli which occupied a relative right position independent of the visual field stimulated and RTs to LVF stimuli were longer than RTs to RVF stimuli. Experiment 3 was designed to examine whether the attentional deficit associated with right parietal damage was mostly related to the use of gravitational rather than to retinal coordinates. In this experiment the patients tilted the head either to the left or the right by 90 deg and they responded to two stimuli displayed above and on either side of a fixation mark. The results showed that the difficulty in attending to the left was related both to the gravitational and the retinal frames of reference.
Cognitive Neuropsychology, 1994
The study concerned rehabilitation of spatial neglect by manipulation of spatial attention. The t... more The study concerned rehabilitation of spatial neglect by manipulation of spatial attention. The treatment was limited to the visual modality but extinction and neglect were tested in both visual and tactile modalities. The results showed a clear-cut improvement of visual neglect. Considering that the treatment was based exclusively on manipulating attention, this constitutes strong evidence in favour of the orienting
Journal of The International Neuropsychological Society, 1996
In this paper different models of anosognosia are confronted and data concerning denial behaviors... more In this paper different models of anosognosia are confronted and data concerning denial behaviors are presented that were collected on a selected population of right brain-damaged patients affected by motor and neglect disorders. Anosognosia for motor impairment and anosognosia for cognitive impairments were found to be dissociated, as well as anosognosia for the upper and lower limb motor impairments. These findings are then discussed in an attempt to choose the more suitable theoretical framework for interpreting the various disorders related to denial of illness.
Interpreting the behaviors of others crucially requires the ability to decode the observed kinema... more Interpreting the behaviors of others crucially requires the ability to decode the observed kinematic information into a causal relationship between the motor sequence and its outcome. It has been suggested that this ability depends on action 'simulation'mechanisms mapping observed motor acts onto corresponding motor programs and associated somatosensory consequences stored into the observer's action repertoire (Rizzolatti and Craighero, 2004; Wilson and Knoblich, 2005; Urgesi et al., 2010; Keysers et al., 2010; ...
The study of pathologic behavioral phenomena following damage to the central nervous system has s... more The study of pathologic behavioral phenomena following damage to the central nervous system has substantially contributed to our understanding of the normal organization of cognitive brain functions. The investigation of clinical extinction in neurological patients, for example, revealed that events occurring in the immediate proximity to the body (i.e. in near peripersonal space) undergo a high degree of multisensory processing.
Nature, 1997
Some patients with brain damage fail to identify a sensory stimulus presented on the opposite sid... more Some patients with brain damage fail to identify a sensory stimulus presented on the opposite side to their lesion (contralesional) when a competing stimulus is presented on the same side (ipsilesional) 1 . This phenomenon has become known as extinction. It is commonly ...
Restorative neurology and neuroscience, Jan 8, 2015
The aim of the study is to compare the effects of multiple sessions of cathodal (c-tDCS) or anoda... more The aim of the study is to compare the effects of multiple sessions of cathodal (c-tDCS) or anodal tDCS (a-tDCS) in modulating the beneficial effects of prism adaptation (PA) treatment in neglect patients. 30 neglect patients were submitted to 10 daily sessions of PA treatment. Patients were pseudo-randomly divided into 3 groups. In the c-tDCS-group, each PA session was coupled with 20 minutes of cathodal stimulation of the left, intact PPC; in the a-tDCS-group, anodal stimulation was applied to PPC of the damaged hemisphere; in the Sham group, sham stimulation was applied. Neglect was evaluated before and after treatment with the Behavioral Inattention Test. Combined tDCS-PA treatment induced stronger neglect improvement in the a-tDCS group as compared to the Sham group. No improvement was found in the c-tDCSgroup, with respect to that normally induced by PA and found in the Sham group. c-tDCS abolished neglect amelioration after PA, possibly because stimulation affected the sensor...
Brain and cognition, 2006
Deficits affecting Central Executive System (CES) of working memory (WM) are the main neuropsycho... more Deficits affecting Central Executive System (CES) of working memory (WM) are the main neuropsychological outcome after traumatic brain injury (TBI) and can also explain deficits in other domains, like divided attention, executive functions and long-term memory. For this reason we developed a rehabilitative program based on CES functions and we expected to find an improvement in WM as well as in those cognitive functions controlled by the CES. The experimental group was composed by 9 TBIs, selected for WM deficits, whereas the control group was composed by 6 TBIs, without WM deficits, but with speed processing deficits. All patients performed a cognitive training, based on PASAT (Gronwall & Wrightson, 1981)and two new versions of this task. The results showed in the experimental group an improvement in WM and in the cognitive functions controlled by the CES, whereas control patients did not show any improvement after the cognitive training.
Neuropsychologia, 1993
Based on a test introduced by Tegnér and Levander, Brain114, 1943–1951, 1991, right brain-damaged... more Based on a test introduced by Tegnér and Levander, Brain114, 1943–1951, 1991, right brain-damaged patients were assigned to a group with unilateral perceptual neglect and a group with directional motor neglect. Brain scans showed that all directional motor neglect patients had frontal lesions, whereas in perceptual neglect patients the frontal lobes were always spared. All patients were asked to execute two tasks, which were also administered to a control group. One task consisted in pointing to tokens symmetrically distributed on a display. The other task consisted in picking up the same tokens. The tasks were first executed with the aid of vision and then in a blindfolded condition. In the case of patients with perceptual neglect, performance on the left side was better in the pick-up task than in the pointing task and improved in the blindfolded condition. Neither patients with directional motor neglect nor control patients showed these effects. The results were explained in terms of the hyperattentional hypothesis of perceptual neglect, according to which, in this form of neglect, attention is captured by the objects that lie on the right side of space.
Social cognitive and affective neuroscience, 2015
Human body postures convey useful information for understanding others' emotions and intentio... more Human body postures convey useful information for understanding others' emotions and intentions. To investigate at which stage of visual processing emotional and movement-related information conveyed by bodies is discriminated, we examined event-related potentials elicited by laterally presented images of bodies with static postures and implied-motion body images with neutral, fearful or happy expressions. At the early stage of visual structural encoding (N190), we found a difference in the sensitivity of the two hemispheres to observed body postures. Specifically, the right hemisphere showed a N190 modulation both for the motion content (i.e. all the observed postures implying body movements elicited greater N190 amplitudes compared with static postures) and for the emotional content (i.e. fearful postures elicited the largest N190 amplitude), while the left hemisphere showed a modulation only for the motion content. In contrast, at a later stage of perceptual representation, r...
Neuropsychologia, 2006
Prism adaptation (PA) has been demonstrated to be effective in improving hemispatial neglect. How... more Prism adaptation (PA) has been demonstrated to be effective in improving hemispatial neglect. However not all patients seem to benefit from this procedure. Thus, the objective of the present work is to provide behavioural and neuroanatomical predictors of recovery by exploring the reorganization of low-order visuo-motor behaviour and high-order visuo-spatial representation induced by PA. To this end, 16 neglect patients (experimental group) were submitted to a PA treatment for 10 daily sessions. Neglect and oculo-motor responses were assessed before the treatment, 1 week, 1 and 3 months after the treatment. Eight control patients, who received general cognitive stimulation, were submitted to the same tests at the same time interval. The results showed that experimental patients obtained, as a consequence of PA, a long lasting neglect recovery, a reorganization of low-order visuo-motor behaviour during and after prism exposure (error reduction and after-effect, respectively) and a leftward deviation of oculo-motor responses. Importantly, the level of error reduction obtained in the first week of treatment was predictive of neglect recovery and the amelioration of oculo-motor responses, and the degree of eye movement deviation was positively related to neglect amelioration. Finally, the study of patients' neuroanatomical data showed that severe occipital lesions were associated with a lack of error reduction, poor neglect recovery and reduced oculo-motor system amelioration. In conclusion, the present results suggest that low-order visuo-motor reorganization induced by PA promotes a resetting of the oculo-motor system leading to an improvement in high-order visuo-spatial representation able to ameliorate neglect.
Neuropsychologia, 2010
Auditory and tactile stimuli are integrated within a limited space around the body to form an aud... more Auditory and tactile stimuli are integrated within a limited space around the body to form an auditory peripersonal space (APPS). Here we investigate whether the APPS representation around the hand can be extended through the use of a common technological tool such as the computer mouse. When using a mouse, an action occurring in the space around the hand has a distal effect in the space defined by the computer screen; thus, the mouse virtually links near and far space. Does prolonged experience with the mouse durably extend APPS representation to the far space? We examined 16 habitual mouse users to determine whether a sound presented near the right hand or near the computer screen affected reaction times to a tactile target at the hand. When subjects sat in front of the computer, without holding the mouse, they responded faster to tactile stimuli when sounds were presented near the hand rather than near the screen, consistent with a normal segregation of APPS around the hand. In c...
Neuropsychologia, 2010
Please cite this article in press as: Magosso, E., et al. Neural bases of peri-hand space plastic... more Please cite this article in press as: Magosso, E., et al. Neural bases of peri-hand space plasticity through tool-use: Insights from a combined computational-experimental approach. Neuropsychologia (2009),
NeuroReport, 1998
We infer the functional integration of the visual, auditory and proprioceptive spatial maps from ... more We infer the functional integration of the visual, auditory and proprioceptive spatial maps from the behaviour of a patient (G.A.) with left visual neglect, i.e. a derangement of visual space representation. G.A. was required to point manually to left, centre or right acoustic stimuli, under visual control or blindfolded, with the responding hand (left or right) located either on the left, centre or right space. G.A.'s manual pointing responses to left auditory stimuli were strongly influenced by the visual spatial information and by the proprioceptive spatial information related to the position of the responding effector. In the visual control condition, when the patient performed the task with the left effector located on the left, pointing responses to left auditory stimuli were shifted towards the right intact visual space. In contrast, when the visual spatial information was rendered less salient, i.e. in the blindfolded condition, and the effector was again located on the left, manual pointing responses were confined to the previously ignored left space. These findings are consistent with the view that the acoustic representation is modulated by the impaired visual representation and by the proprioceptive spatial map related to the position of the responding effector.
Neuropsychologia, 2001
There have been many studies of visuospatial neglect, but fewer studies of neglect in relation wi... more There have been many studies of visuospatial neglect, but fewer studies of neglect in relation with other sensory modalities. In the present study we investigate the performance of six right brain damaged (RBD) patients with left visual neglect and six RBD patients without neglect in an auditory spatial task. Previous work on sound localisation in neglect patients adopted measure of sound localisation based on directional motor responses (e.g., pointing to sounds) or judgement of sound position with respect to the body midline (auditory midline task). However, these measures might be influenced by non-auditory biases related with motor and egocentric components. Here we adopted a perceptual measure of sound localisation, consisting in a verbal judgement of the relative position (same or different) of two sequentially presented sounds. This task was performed in a visual and in a blindfolded condition. The results revealed that sound localisation performance of visuospatial neglect patients was severely impaired with respect to that of RBD controls, especially when sounds originated in contralesional hemispace. In such condition, neglect patients were always unable to discriminate the relative position of the two sounds. No difference in performance emerged as a function of the visual condition in either group. These results demonstrate a perceptual deficit of sound localisation in patients with visuospatial neglect, suggesting that the spatial deficits of these patients can arise multimodally for the same portion of external space.
Neuropsychologia, 2002
Possible auditory deficits in neglect were examined by comparing the performance of four right br... more Possible auditory deficits in neglect were examined by comparing the performance of four right brain-damaged (RBD) patients with left visuospatial neglect, versus four RBD patients without neglect, in three auditory tasks. The first task required speeded discrimination of sound elevation, by moving a central lever up or down according to the vertical position of a peripheral target sound, regardless of its side. The other two auditory tasks were non-spatial, requiring either speeded pitch discrimination (moving the central lever up for high pitch, down for low pitch) or speeded target detection. Neglect patients' performance was impaired with respect to RBD controls only when the auditory task required spatial coding of the target sound (the up/down spatial discrimination). This demonstrates a selective deficit of auditory space perception in neglect patients. This auditory spatial deficit was more pronounced for left than right sounds. Since auditory space perception was impaired in the 6ertical dimension, the observed deficit cannot be attributed to a systematic rightward shift in sound localisation. Instead, the results suggest increased spatial uncertainty in sound localisation by neglect patients, particularly for auditory targets on the contralesional side. These findings are related to multimodal coding of space in the parietal cortex, which was damaged in the neglect patients, but not in the RBD controls.
Trends in Cognitive Sciences, 2002
In order to code visual peripersonal space, human and non-human primates need an integrated syste... more In order to code visual peripersonal space, human and non-human primates need an integrated system that controls both visual and tactile inputs within peripersonal space around the face and the hand, based on visual experience of body parts. The existence of such a system in humans has been demonstrated, and there is evidence showing that visual peripersonal space relating to the hand has important dynamic properties, for example, it can be expanded and contracted depending on tool use. There is also evidence for a high degree of functional similarity between the characteristics of the visual peripersonal space in humans and in monkeys.
Trends in Cognitive Sciences, 2003