Biography:

In the past Tim Shallice has collaborated on articles with Anthony I Jack and Peter McLeod. One of their most recent publications is NoteThe dissociation between short term retention of meaningful sounds and verbal material. Which was published in journal Neuropsychologia.

More information about Tim Shallice research including statistics on their citations can be found on their Copernicus Academic profile page.

Tim Shallice's Articles: (19)

NoteThe dissociation between short term retention of meaningful sounds and verbal material

AbstractTwo patients with a specific deficit of auditory verbal short-term memory were tested on two tasks of short-term retention, one involving verbal material—letters—and the other non-verbal material—meaningful sounds. There was a striking dissociation between performance on the two tasks, only their performance on the verbal tasks being impaired. The results are discussed in the context of the function of this short-term memory system.

The possible role of selective attention in acquired dyslexia

AbstractLiteral dyslexia, the inability to read letters within a word which itself could be read, was analysed in two patients. Their impairment was found not to be specific to letters but to stimuli in which more than one item of the same category was simultaneously present in the visual field. Thus a letter surrounded by numbers could be read more easily than if surrounded by other letters. Explanations in terms of visual disorientation or implicit response interference were rejected. It is suggested that their impairment arises from a specific defect at the level at which visual input is selected for meaningful analysis.

Introspective physicalism as an approach to the science of consciousness

AbstractMost ‘theories of consciousness’ are based on vague speculations about the properties of conscious experience. We aim to provide a more solid basis for a science of consciousness. We argue that a theory of consciousness should provide an account of the very processes that allow us to acquire and use information about our own mental states – the processes underlying introspection. This can be achieved through the construction of information-processing models that can account for ‘Type-C’ processes. Type-C processes can be specified experimentally by identifying paradigms in which awareness of the stimulus is necessary for an intentional action. The Shallice (1988b) framework is put forward as providing an initial account of Type-C processes, which can relate perceptual consciousness to consciously performed actions. Further, we suggest that this framework may be refined through the investigation of the functions of prefrontal cortex. The formulation of our approach requires us to consider fundamental conceptual and methodological issues associated with consciousness. The most significant of these issues concerns the scientific use of introspective evidence. We outline and justify a conservative methodological approach to the use of introspective evidence, with attention to the difficulties historically associated with its use in psychology.

Attractor dynamics in word recognition: converging evidence from errors by normal subjects, dyslexic patients and a connectionist model

AbstractPeople make both semantic and visual errors when trying to recognise the meaning of degraded words. This result mirrors the finding that deep dyslexic patients make both semantic and visual errors when reading aloud. We link the results with the demonstration that a recurrent connectionist network which produces the meaning of words in response to their spelling pattern produces this distinctive combination of errors both when its input is degraded and when it is lesioned. The reason why the network can simulate the errors of both normal subjects and patients lies in the nature of the attractors which it develops as it learns to map orthography to semantics. The key role of attractor structure in the successful simulation suggests that the normal adult semantic reading route may involve attractor dynamics.

Special Issue: Original ArticlePatterns of Peripheral Paralexia: Pure Alexia and the Forgotten Visual Dyslexia?

AbstractThe concept of visual dyslexia put forward by Marshall and Newcombe (1973) is assessed. After a long period of neglect it was resurrected in the late 1990s in a narrow form. In the current paper it is proposed that a wider form of the functional syndrome is useful to include amongst other conditions attentional dyslexia and neglect dyslexia. The variety of sub-forms would correspond to the behavioural effects of the different ways in which the orthographic processing systems can be impaired. What distinguishes the broader form from pure alexia is that the patient lacks the capacity to use a serial letter processing strategy, and so interpretation of visual dyslexia in terms of the impairment to the orthographic processing systems is not contaminated by the use of a compensatory strategy that results in processing operations which are qualitatively very different from the normal and highly opaque. The lack of a serial letter processing strategy makes visual dyslexia a much more transparent functional syndrome.

Research reportRight posterior cortical functions in a tumour patient series

AbstractIt is standardly believed that the localisation of cognitive function by means of impairments arising from cortical tumour is not possible as the functional defects that result are mild and unspecific. These assumptions were not supported in an investigation of four processes generally sensitive to right posterior cortical lesions, when patients with parieto-occipital lesions were compared with prefrontal ones. In three of the tests loading on the individual processes – Reaching Accuracy, Star Cancellation, Fragmented Letters and Cube Analysis – parieto-occipital impairments were found in the basic groups analysis and this was so in the right-hemisphere group. More critically, in these tests Lesion Behaviour Mapping showed the critical lesion site for the tests to have relatively little overlap with those of the other tests, indicating that the cognitive effects were not widespread and diffuse. In addition, in three of the tests the critical lesion sites fitted localisations arrived from other procedures. Patients with high-grade tumours performed considerably worse than those with low-grade tumours in only two of the tests (Star Cancellation, Cube Analysis) particularly in the right parieto-occipital group. In three (Reaching Accuracy, Star Cancellation, Cube Analysis) there was a deterioration with the operation specifically in the low-grade tumour patients. It is suggested that a tumour patient series may provide converging evidence for the localisation of a function initially obtained by some other procedure.

The Involvement of the Frontal Lobes in Cognitive Estimation1

SummaryNinety-six patients with localised cerebral lesions were tested on a task of providing reasonable answers to Cognitive Estimate questions. These questions are ones that can be answered using general knowledge available to almost all subjects, but for which no immediately obvious strategy is available. It was found that patients with frontal lesions gave significantly more bizarre answers than patients with more posterior lesions. This effect is interpreted in terms of Luria's (1966) theory of the planning functions of the frontal lobes.

Bizarre Responses, Rule Detection and Frontal Lobe Lesions

AbstractSeventy-seven patients with different cerebral lesions were tested on a rule-detection task where the stimuli were designed in such a way as to minimize the activation of pre-existing schemata. Patients with lesions involving the frontal lobes were poorer at achieving set than patients with lesions elsewhere. In addition, the anteriorly-lesioned group showed a greater tendency to guess and were more likely to abandon a correct rule once it had been attained, but there were no differences between the groups in incidence of perseverative responses. Various plausible explanations of these results are examined, with the most favoured account suggesting that anterior patients show an exaggerated willingness to adopt bizarre hypotheses.

Multiple frontal systems controlling response speed

AbstractThis study evaluated a model of attention that postulates several distinct component processes, each mediated by specific neural systems in the human frontal lobes. A series of reaction time (RT) tests (simple, choice, and prepare) examined the hypothesis that different attentional processes are related to distinct regions within the frontal lobes. These tests were given to 38 patients with frontal lesions and 38 age-matched control subjects. Lesions were localized both by general regions (superior medial, inferior medial, left and right lateral) and by individual architectonic areas. Lesions in the superior medial (SM) frontal lobes, particularly involving areas 24 and 32 on the right, were associated with slow RT in all tests and with failure to decrease RT after a warning signal. Lesions in the right lateral (RL) frontal lobe, centred in area 9/46v, prevented the decrease in RT with increasing foreperiod that was seen in normal subjects and in patients with lesions elsewhere in the frontal lobes. The ability to energize a response for rapid RT, either generally or specifically following a warning stimulus, is sensitive to lesions of the right SM. Monitoring of stimulus occurrence and response behaviour in order to enhance the speed of response to upcoming stimuli is sensitive to RL lesions.

Dynamic aphasia in progressive supranuclear palsy: A deficit in generating a fluent sequence of novel thought

AbstractWe report a patient (KAS) who presented with pure dynamic aphasia in the context of progressive supranuclear palsy (PSP). KAS had the hallmark propositional language impairment in the context of preserved naming, reading, repetition and comprehension skills. The severity of KAS's propositional language deficit was demonstrated to be comparable to other dynamic aphasic patients. Remarkably, despite virtually abolished propositional speech, KAS was unimpaired on word and sentence level generation tasks that required a single response. This dissociation was further investigated on two discourse level generation tasks that required the generation of multiple connected sentences. Quantitative production analysis and novelty measures demonstrated that her performance was extremely reduced and characterised by a lack of novel words and sentences and a tendency to perseverate. This pattern of performance suggests that there may be two subtypes of dynamic aphasia. Patients with the more documented first subtype have language-specific deficits, fail word and sentence level generation tests and have left inferior frontal gyrus lesions. Patients with the second subtype, like KAS, pass word and sentence level generation tests and fail discourse level generation tests. They have a verbal and non-verbal generation deficit and bilateral frontal and subcortical damage. Our findings are discussed with reference to executive functioning accounts of dynamic aphasia and models of speech production. We interpret our patients’ impairment as being underpinned by a deficit in one set of mechanisms involved in discourse generation; namely the generation of a fluent sequence of novel thought.

Fractionation of memory in medial temporal lobe amnesia

AbstractWe report a comprehensive investigation of the anterograde memory functions of two patients with memory impairments (RH and JC). RH had neuroradiological evidence of apparently selective right-sided hippocampal damage and an intact cognitive profile apart from selective memory impairments. JC, had neuroradiological evidence of bilateral hippocampal damage following anoxia due to cardiac arrest. He had anomic and “executive” difficulties in addition to a global amnesia, suggesting atrophy extending beyond hippocampal regions. Their performance is compared with that of a previously reported hippocampal amnesic patient who showed preserved recollection and familiarity for faces in the context of severe verbal and topographical memory impairment [VC; Cipolotti, L., Bird, C., Good, T., Macmanus, D., Rudge, P., & Shallice, T. (2006). Recollection and familiarity in dense hippocampal amnesia: A case study. Neuropsychologia, 44, 489–506.] The patients were administered experimental tests using verbal (words) and two types of non-verbal materials (faces and buildings). Receiver operating characteristic analyses were used to estimate the contribution of recollection and familiarity to recognition performance on the experimental tests. RH had preserved verbal recognition memory. Interestingly, her face recognition memory was also spared, whilst topographical recognition memory was impaired. JC was impaired for all types of verbal and non-verbal materials. In both patients, deficits in recollection were invariably associated with deficits in familiarity. JC's data demonstrate the need for a comprehensive cognitive investigation in patients with apparently selective hippocampal damage following anoxia. The data from RH suggest that the right hippocampus is necessary for recollection and familiarity for topographical materials, whilst the left hippocampus is sufficient to underpin these processes for at least some types of verbal materials. Face recognition memory may be adequately subserved by areas outside of the hippocampus.

Qualitatively different memory impairments across frontal lobe subgroups

AbstractRecall impairments in patients with lesions to the prefrontal cortex (PFC) have variously been attributed to problems with organisation at encoding, organisation at retrieval and monitoring at retrieval. Neuroimaging and recent theoretical work has associated the left lateral PFC with organisation and strategy production at encoding, and the right lateral PFC with organisation, error detection and monitoring at retrieval. However few lesion studies have been anatomically specific enough to test the direct predictions made by this work. Proactive interference, response to prompting, monitoring and organisational strategies were examined in 34 patients with frontal lobe lesions and 50 healthy controls using a structured verbal recall task, and the fractionation of deficits according to specific frontal lesion site was explored. Recall impairments were observed in the Right Lateral and Medial frontal subgroups. The Medial recall impairment was unaffected by manipulations at encoding or retrieval and was attributed to a “pure” memory deficit arising from disruption of the limbo-thalamic system. The Right Lateral recall impairment was ameliorated by the provision of prompts at retrieval, indicating a strategic retrieval deficit. This intervention also resulted in an unusual pattern of intrusions, namely an increase in proactive interference responses compared with extra-list intrusions. However contrary to predictions no monitoring impairment was found. We offer two explanations for the pattern of performance in the Right Lateral group: failure of a right lateralised error detection and checking system, or an impairment in the active uncued initiation of a supervisory operation.

Effect of frontal lobe lesions on the recollection and familiarity components of recognition memory

AbstractSingle-process theories assume that familiarity is the sole influence on recognition memory with decisions being made as a continuous process. Dual-process theories claim that recognition involves both recollection and familiarity processes with recollection as a threshold process. Although, the frontal lobes of the brain play an important role in recognition memory, few studies have examined the effect of frontal lobe lesions on recollection and familiarity. In the current study, the nonverbal recognition memory of 24 patients with focal frontal lesions due to tumour or stroke was examined. Recollection and familiarity were estimated using the receiver operating characteristic (ROC) method. A secondary analysis was also conducted using standard signal detection theory methodology. Both analyses led to similar conclusions where only the familiarity component of recognition memory was impaired in frontal patients compared to healthy controls whilst the recollection-type (or variance ratio) processes remained intact.

Cortical bases of elementary deductive reasoning: Inference, memory, and metadeduction

AbstractElementary deduction is the ability of unreflectively drawing conclusions from explicit or implicit premises, on the basis of their logical forms. This ability is involved in many aspects of human cognition and interactions. To date, limited evidence exists on its cortical bases. We propose a model of elementary deduction in which logical inferences, memory, and meta-logical control are separable subcomponents. We explore deficits in patients with left, medial and right frontal lesions, by both studying patients’ deductive abilities and providing measures of their meta-logical sensitivity for proof difficulty. We show that lesions to left lateral and medial frontal cortex impair abilities at solving elementary deductive problems, but not so lesions to right frontal cortex. Furthermore, we show that memory deficits differentially affect patients according to the locus of the lesion. Left lateral patients with working memory deficits had defective deductive abilities, but not so left lateral patients with spared working memory. In contrast, in medial patients both deductive and meta-deductive abilities were affected regardless of the presence of memory deficits. Overall, the results are compatible with a componential view of elementary deduction, and call for the elaboration of more fine-grained models of deductive abilities.

Functional anatomy of temporal organisation and domain-specificity of episodic memory retrieval

AbstractEpisodic memory provides information about the “when” of events as well as “what” and “where” they happened. Using functional imaging, we investigated the domain specificity of retrieval-related processes following encoding of complex, naturalistic events. Subjects watched a 42-min TV episode, and 24 h later, made discriminative choices of scenes from the clip during fMRI. Subjects were presented with two scenes and required to either choose the scene that happened earlier in the film (Temporal), or the scene with a correct spatial arrangement (Spatial), or the scene that had been shown (Object). We identified a retrieval network comprising the precuneus, lateral and dorsal parietal cortex, middle frontal and medial temporal areas. The precuneus and angular gyrus are associated with temporal retrieval, with precuneal activity correlating negatively with temporal distance between two happenings at encoding. A dorsal fronto-parietal network engages during spatial retrieval, while antero-medial temporal regions activate during object-related retrieval. We propose that access to episodic memory traces involves different processes depending on task requirements. These include memory-searching within an organised knowledge structure in the precuneus (Temporal task), online maintenance of spatial information in dorsal fronto-parietal cortices (Spatial task) and combining scene-related spatial and non-spatial information in the hippocampus (Object task). Our findings support the proposal of process-specific dissociations of retrieval.

Cognitive reserve and cognitive performance of patients with focal frontal lesions

Highlights•Effect of cognitive reserve (CR) proxies in focal unilateral lesions.•NART IQ accounts for a larger proportion of variance in executive and naming skills.•Age predicts performance on executive, fluid intelligence, speed and perception tests.•Education and NART IQ did not modify the effect of lesion severity on cognitive impairment.

Regular articleFunctional imaging and neuropsychology findings: how can they be linked?

AbstractIt is argued that in poorly understood domains functional imaging and neuropsychology findings on cognitive processes can be related only through functional models of normal cognition. The psychological concept of “resource” can, however, be simply extrapolated to functional imaging. It is then argued that double dissociations can have analogous inferential power for extrapolation to models of normal cognition in functional imaging as in neuropsychology. The argument is illustrated by the example of the control processes involved in functional episodic memory imaging of experiments.

Neural basis of pantomiming the use of visually presented objects

AbstractNeuropsychological studies of patients suffering from apraxia strongly imply a left hemisphere basis for skilful object use, the neural mechanisms of which, however, remain to be elucidated. We therefore carried out a PET study in 14 healthy human volunteers with the aim to isolate the neural mechanisms underlying the sensorimotor transformation of object-triggers into skilled actions. We employed a factorial design with two factors (RESPONSE: naming, pantomiming; and TRIGGER: actions, objects) and four conditions (IA: imitating the observed pantomime; IO: pantomiming the use of the object shown; NA: naming the observed pantomime; NO: naming the object shown). The design thus mainly aims at investigating the interaction [i.e. (IO–IA)–(NO–NA)] which allows the assessment of increased neural activity specific to the sensorimotor transformation of object-triggers into skilled actions. The results (P < 0.05, corrected) showed that producing a wide range of skilled actions triggered by objects (controlled for perceptual, motor, semantic, and lexical effects) activated left inferior parietal cortex. The data provide an explanation for why patients with lesions including left parietal cortex suffer from ideational apraxia as assessed by impaired object use and pontomining to visually presented objects (Brain 111 (1988) 1173; Cogn. Neuropsychol. 18 (2001) 671).

Original ArticleLong-Term Cognitive Functioning and Psychological Well-Being in Surgically Treated Patients with Low-Grade Glioma

ObjectiveThe aim of this work is to provide an in-depth investigation of the impact of low-grade gliomas (LGG) and their surgery on patients' cognitive and emotional functioning and well-being, carried out via a comprehensive and multiple-measure psychological and neuropsychological assessment.Patients and MethodsFifty surgically treated patients with LGG were evaluated 40 months after surgery on their functioning over 6 different cognitive domains, 3 core affective/emotional aspects, and 3 different psychological well-being measures to obtain a clearer picture of the long-term impact of illness and surgery on their psychological and relational world. Close relatives were also involved to obtain an independent measure of the psychological dimensions investigated.ResultsCognitive status was satisfactory, with only mild short-term memory difficulties. The affective and well-being profile was characterized by mild signs of depression, good satisfaction with life and psychological well-being, and good personality development, with patients perceiving themselves as stronger and better persons after illness. However, patients showed higher emotional reactivity, and psychological well-being measures were negatively affected by epileptic burden. Well-being was related to positive affective/emotional functioning and unrelated to cognitive functioning. Good agreement between patients and relatives was found.ConclusionsIn the long-term, patients operated on for LGG showed good cognitive functioning, with no significant long-term cognitive sequelae for the extensive surgical approach. Psychologically, patients appear to experience a deep psychological change and maturation, closely resembling that of so-called posttraumatic growth, which, to our knowledge, is for the first time described and quantified in patients with LGG.

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