Cognitive rehabilitation: attention and neglect

doi:10.1016/S1364-6613(99)01378-9

Trends in Cognitive Sciences

Volume 3, Issue 10, 1 October 1999, Pages 385-393

https://doi.org/10.1016/S1364-6613(99)01378-9 Get rights and content

Abstract

Cognitive neuroscience can make a significant contribution towards the development of a scientific basis for the practice of brain rehabilitation. Though rehabilitation is a vast worldwide industry, there is little scientific basis for the training and therapy that are designed to help damaged brain circuits to recover. The systematic application of cognitive neuroscience models to rehabilitation can not only foster better, more theoretically grounded rehabilitation, but the models themselves can be tested and modified by data generated in rehabilitation-oriented research. The example of unilateral spatial neglect is used here to show how non-intuitive but clinically tractable methods can emerge out of systematic application of cognitive neuroscience to the problem of how to foster dynamic change and recovery in the damaged brain. Examples are given of recently developed rehabilitation methods for unilateral spatial neglect that are both derived from theoretical models of cognitive function, and that feed back into these models. These include dorsal–ventral stream interactions, perceptuo–motor interactions, interhemispheric inhibitory dynamics, and arousal–spatial attention interactions. It will be to the mutual benefit of basic cognitive neuroscience and rehabilitation if this type of research is expanded into other domains of cognitive function, in which similar theory–practice interactions exist.

Section snippets

What is rehabilitation?

The recent research literature has seen the dramatic disconfirmation of a long-held, central assumption about the brain – that new cell bodies cannot emerge in adulthood. In both humans and animals, recent data shows that in the hippocampus, new cells can indeed be produced4, 5, 6. What’s more, this process is partly experience-dependent: animals kept in enriched compared to impoverished environments show more cell genesis in the hippocampus⁷. This finding follows close on the heels of another

Unilateral spatial neglect

Acquired damage to structures of the right hemisphere (usually) including the parietal lobe, dorsolateral and medial frontal lobes and portions of the reticular formation can lead to the phenomenon of unilateral spatial neglect – a failure, difficulty or slowness in reporting or interacting with objects (or sounds or representations) in contralateral hemispace (most frequently left space, as right-hemisphere lesions are most common)16, 17, 18 (see Box 2). An example of unilateral neglect shown

The dorsal/ventral distinction applied to rehabilitation of neglect

The interaction of the brain’s perceptual and motor systems is a topic of considerable current interest, particularly in the light of evidence that some visual information might have privileged access to the control of motor responses, yet not be available to awareness. The notion that the so-called dorsal stream²⁸ can provide visual information for the motor system that is not available to awareness has received strong evidence from a series of experiments by Goodale and Milner29, 30 (and see

Joining forces: combined activation of related attentional circuits

The observation that unilateral neglect can be modified by the motoric aspects of the task was consistent with a view that complex bi-directional relationships exist between perception and action³⁶. Several studies have shown that even small movements with the left hand on the left side of space produced significant reductions in visuo-spatial neglect, in contrast to an absence of such effects with right hand moves on the left, or left hand moves on the right37, 38, 39.

These data have been

Overcoming inhibition

The ‘Sprague effect’ described earlier in this review showed that the effects of a lesion can spread far beyond the specific functions controlled by the particular neural circuitry that has been damaged²⁵. In arguing (in the previous section) that limb-activation training had its effects in part through the combined activation of partner circuits in the damaged hemisphere overcoming inhibition from the other hemisphere, we have an example of the two-way interchange between theory and practice

Non-obvious interactions among attentional systems: the case of arousal and neglect

Analysing the cognitive architecture of spatial attention has so far suggested two types of rehabilitative process: joint activation of mutually facilitatory networks, and reduction of inhibitory competition. Another example of the mutual facilitation process draws on evidence from the lawful interaction of two apparently very different and non-obviously related types of cognitive process – the arousal/sustained-attention systems of the brain on one hand, and the spatial-attention system on the

Experience-dependent plastic reorganization?

All the previous examples of rehabilitation concerned methods for temporarily boosting activation to the lesioned attentional networks, either by co-activation of sister circuits or by the reduction of inhibition by competitor circuits. In each case, plausible mechanisms could be invoked to explain the non-transient (ranging from hours to days) improvements shown as a result of the training. In the rod-grasping study we invoked increased awareness of the deficit induced by the perceptual

Conclusion

In summary, theory-based rehabilitation research produces therapies in which the underlying mechanisms of improvement can be studied in detail, so that these therapies can be improved and developed along scientific lines. Just as important, however, is the way in which such research feeds back into the models of cognitive neuroscience from which they were derived. This mutually beneficial enterprise is not confined to unilateral neglect – the approach is being applied to a wide range of other

Outstanding questions

•
While it is known that long-term changes in synaptic connectivity, including dendritic and axonal sprouting, can occur as a result of behaviour and experience⁷⁰, little is known about the parameters such as timing, duration and frequency of such stimulation in different cognitive realms. When, how much, and how often should we provide such stimulation? What type of stimulation should we be giving, based on knowledge of the cognitive architecture of the affected systems?
•
Experience-dependent

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2022, Comprehensive Psychiatry
Major Depression Disorder (MDD) and Generalized Anxiety Disorder (GAD) often co-occur, but the neurocognitive mechanisms of this co-occurrence remain unknown. Prominent views have pointed to attentional processes as potent mechanisms at play in MDD and GAD, respectively. Yet uncertainty remains regarding the very nature of attentional impairments in patients with co-occurring MDD and GAD.
Inspired by contemporary models of attentional networks, we compared the three main attentional networks, namely the orienting, alerting, and executive networks of the Attention Network Task's model, in four groups of patients with, respectively, co-occurring DSM-5 MDD and GAD (n = 30), DSM-5 MDD only (n = 30), DSM-5 GAD only (n = 30), or free from any DSM-5 diagnosis (n = 30). To capture the multivariate nature of our data, we examined between-group differences in the attentional networks through a multivariate analysis of variance.
Patients with co-occurring MDD and GAD exhibited more severe impairments in the executive control network than those with only one of the disorders. Although patients with MDD or GAD solely did not differ in terms of attentional impairments, both groups showed significantly more impairments in the executive control network than those free from any DSM-5 diagnosis (all Bonferonni-corrected post-hoc ps < 0.05).
Our findings align with a longstanding staging approach to comorbidity whereby, via synergistic effects, co-occurring disorders produce more damages than the sum of each disorder. Here, for the first time, we extended this approach to the executive network of attention in the context of the co-occurrence between MDD and GAD.
Pharmacological Treatment of Visuospatial Neglect: A Systematic Review
2017, Journal of Stroke and Cerebrovascular Diseases
Citation Excerpt :
Dopaminergic and (nor)adrenergic stimulations decreased VSN symptoms in some cases. Hence, the alerting (noradrenaline) and executive (dopamine) networks might influence VSN as well.32-34 In the current review, it is clear that none of the studies, no matter what class of medicaments, showed a clear-cut improvement of VSN post stroke.
The aims of the current review were (1) to give an overview of human studies investigating pharmacotherapy to ameliorate visuospatial neglect and (2) to evaluate the quality of those studies.
A systematic literature search using PubMed, Scopus, and ResearchGate was conducted in regard to studies that evaluated pharmacological interventions aiming to ameliorate poststroke visuospatial neglect. The search was limited in the following features: species (human), adults (≥18 years of age), language (English), and type of neglect (visuospatial). Two independent authors extracted data on study content and effectiveness and evaluated the quality of studies and methods.
A total of 11 studies were identified. Three studies were considered to be of moderate quality, the others of low quality. Seven studies represented dopaminergic treatment; 3 studies represented cholinergic treatment; and 1 study represented noradrenergic treatment. Three dopaminergic studies showed primarily positive effects of dopaminergic stimulation on visuospatial neglect, whereas three others showed adverse effects. All 3 cholinergic studies found positive effects in some outcome measures concerning visuospatial neglect. Noradrenergic stimulation improved maintenance of attention when exploring space.
Currently, cholinergic therapy might be the best option for future research. However, we must emphasize the explorative nature and the limited quality of the reviewed studies.
Transcranial direct current stimulation to the parietal cortex in hemispatial neglect: A feasibility study
2015, Neuropsychologia
Prior research suggests that dampening neural activity of the intact, presumably overactive hemisphere, combined with increasing neural activity in the damaged hemisphere, might restore cortical interhemispheric balance and reduce neglect. In the present study we repeatedly applied a relatively new technique, transcranial direct current stimulation (tDCS), to the posterior parietal cortex to modulate spontaneous neural activity levels in a polarity dependent fashion to find evidence for improvements in severe hemispatial neglect in chronic patients.
Eighty-nine patients were initially identified from our databases as having neglect, after thoroughly screening databases, consulting medical practitioners and baseline testing, only five met our inclusion criteria and agreed to participate. Sixty-five patients were excluded as they did not meet safety criteria for tDCS (epilepsy, metal implants), suffered from other medical conditions (i.e., heart disease, epilepsy, current psychiatric disorder) or displayed only mild neglect at baseline testing. Five patients with severe chronic hemispatial neglect were enrolled in a double-blind, placebo-controlled treatment program. TDCS or placebo was applied for 20 minutes over the left (cathodal) and right (anodal) posterior parietal cortex at an intensity of 2 mA on five consecutive days. Treatment conditions were separated by a four week wash-out period. Baseline corrected change in performance on the conventional subtests of the Behavioral Inattention Test (BIT) was our primary endpoint.
No treatment-related effects were observed for the BIT change scores and performance on individual subtests. Moreover, patients' performance somewhat improved only during the stimulation period (day one vs day five, irrespective of whether it was placebo or tDCS), but not thirty days later, indicating a practice effect.
The present study does not provide evidence that tDCS to the posterior parietal cortex improves chronic hemispatial neglect. As a result of in- and exclusion health and safety criteria the majority of patients were excluded, which indicates that performing large randomized controlled trials is not feasible in chronic neglect patients.
Tinnitus specifically alters the top-down executive control sub-component of attention: Evidence from the Attention Network Task
2014, Behavioural Brain Research
Citation Excerpt :
In view of the present results, rehabilitation strategies should be adapted to focus on attentional remediation of executive control, whereas rehabilitating the preserved alerting and orienting networks appears of little usefulness. Several procedures have already been developed to specifically rehabilitate each attentional network [61–63], and those focusing on executive control rehabilitation [64,65] could be adapted to TS. Recently it has also been suggested that mindfulness training may have impact on executive control of attention [e.g. 66,67].
Tinnitus can be defined as the perception of noxious disabling internal sounds in the absence of external stimulation. While most individuals with tinnitus show some habituation to these internal sounds, many of them experience significant daily life impairments. There is now convincing evidence that impairment in attentional processes may be involved in tinnitus, particularly by hampering the habituation mechanism related to the prefrontal cortex activity. However, it is thus still unclear whether this deficit is an alteration of alerting and orienting attentional abilities, or the consequence of more general alteration in the executive control of attention. In the present study, 20 tinnitus patients were compared to 20 matched healthy controls using the Attention Network Test, to clarify which attentional networks, among alerting, orienting, and executive networks, show differences between the groups. The results showed that patients with tinnitus do not present a general attentional deficit but rather a specific deficit for top-down executive control of attention. This deficit was highly correlated with patient characteristics of years of tinnitus duration and the frequency of coping strategies employed to alleviate tinnitus distress in daily life. These findings are discussed in terms of recent neurobiological models suggesting that prefrontal cortex activity might especially be related to tinnitus habituation. Therapeutic perspectives focusing both on rehabilitation of the executive control of attention and neuromodulation are also discussed.
Immediate effects of exposure to positive and negative emotional stimuli on visual search characteristics in patients with unilateral neglect
2013, Neuropsychologia
The performance of patients with unilateral neglect (UN) in tasks demanding visual attention is characterized by contralesional disadvantage which is markedly unstable in magnitude. Such instability of the attentional system is seen very clearly in clinical practice and thus far has no satisfying explanation. Here we examined the immediate effect of exposure to non-lateralized emotional stimuli on UN patients' attentional bias and performance variability. We tested eight right-hemisphere damaged stroke patients with left-sided neglect and eight age-matched healthy subjects in a visual conjunction-search task, each trial performed immediately after viewing a centrally-presented picture, which was emotionally negative, positive or neutral. Both performance bias and variability in performing the search task was analyzed as a function of the valence of the picture, and a method for analyzing reaction time (RT) variance in a small sample is introduced. Overall, UN subjects, but not controls, were slower and more variable in their RT for left- compared to right-sided targets. In the UN group, detecting left-sided targets was significantly slower in trials that followed presentation of negative pictures as compared to positive pictures, regardless of the fact that both picture types were judged as equally arousing by the patients. Moreover, UN patients exhibited larger performance variance on the left then on the right, and negative emotional stimuli were associated with larger variance asymmetry than positive emotional stimuli. Examining the coefficient of variation pointed to a possible dissociation between the effects of emotional stimuli on the lateralized RT mean (reflecting attentional bias) and on the lateralized RT variance (reflecting system instability). We conclude that emotional stimuli affect the spatial imbalance of both performance speed and stability in UN patients.
Neuropsychological Rehabilitation: Critical Analysis
2013, Neuropsychological Rehabilitation

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Trends in Cognitive Sciences

ReviewCognitive rehabilitation: attention and neglect

Abstract

Section snippets

What is rehabilitation?

Unilateral spatial neglect

The dorsal/ventral distinction applied to rehabilitation of neglect

Joining forces: combined activation of related attentional circuits

Overcoming inhibition

Non-obvious interactions among attentional systems: the case of arousal and neglect

Experience-dependent plastic reorganization?

Conclusion

Outstanding questions

Age Ageing

Arch. Phys. Med. Rehabil.

Neuropsychology

Neuropsychologia

Neuropsychologia

Brain

Neurocase

Neuropsychol. Rehab.

Neuropsychologia

J. Clin. Exp. Neuropsychol.

J. Int. Neuropsychol. Soc.

Brain Lang.

The results of clinical trials in stroke rehabilitation research

Arch. Neurol.

The relationship between lateralised and non-lateralised attentional deficits in unilateral neglect

Neurogenesis in the adult human hippocampus

Nat. Med.

Neurogenesis in the dentate gyrus of the adult tree shrew is regulated by psychosocial stress and NMDA receptor activation

J. Neurosci.

Neurogenesis in adulthood: a possible role in learning

Trends Cognit. Sci.

Environmental stimulation of 129/SvJ mice causes increased cell proliferation and neurogenesis in the adult dentate gyrus

Curr. Biol.

Plasticity in the frequency representation of primary auditory cortex

J. Neurosci.

Large-scale plasticity of the human motor cortex

NeuroReport

Restoration of Function after Brain Injury

Rehabilitation of brain damage: brain plasticity and principles of guided recovery

Psychol. Bull.

Synaesthesia in phantom limbs induced with mirrors

Proc. R. Soc. London Ser. B

Visual disorientation with special reference to lesions of the right hemisphere

Brain

Disorders of visual space perception associated with the right hemisphere

Brain

Spatial Neglect: A Clinical Handbook for Diagnosis and Treatment

Spatial hemineglect in humans

Trends Cognit. Sci.

Hemineglect in humans

Unilateral spatial neglect and recovery from hemiplegia: a follow-up study

Brain

The influence of visual neglect on stroke rehabilitation

Stroke

Interaction of cortex and superior colliculus in mediation of visually guided behaviour in the cat

Science

Review
Cognitive rehabilitation: attention and neglect