What is the relationship between Aphantasia, Synaesthesia and Autism?

For people with aphantasia, visual imagery is absent or markedly impaired. Here, we investigated the relationship between aphantasia and two other neurodevelopmental conditions also linked to imagery differences: synaesthesia, and autism. In Experiment 1a and 1b, we asked whether aphantasia and synaesthesia can co-occur, an important question given that synaesthesia is linked to strong imagery. Taking grapheme-colour synaesthesia as a test case, we found that synaesthesia can be objectively diagnosed in aphantasics, suggesting visual imagery is not necessary for synaesthesia to occur. However, aphantasia influenced the type of synaesthesia experienced (favouring 'associator' over 'projector' synaesthesia - a distinction tied to the phenomenology of the synaesthetic experience). In Experiment 2, we asked whether aphantasics have traits associated with autism, an important question given that autism - like aphantasia - is linked to weak imagery. We found that aphantasics reported more autistic traits than controls, with weaknesses in imagination and social skills.

Hyperglycaemia-related complications at the time of diagnosis can cause permanent neurological disability in children with neonatal diabetes.

BACKGROUND: Children with neonatal diabetes often present with diabetic ketoacidosis and hence are at risk of cerebral oedema and subsequent long-term neurological deficits. These complications are difficult to identify because neurological features can also occur as a result of the specific genetic aetiology causing neonatal diabetes. CASE REPORTS: We report two cases of neonatal diabetes where ketoacidosis-related cerebral oedema was the major cause of their permanent neurological disability. Case 1 (male, 18 years, compound heterozygous ABCC8 mutation) and case 2 (female, 29 years, heterozygous KCNJ11 mutation) presented with severe diabetic ketoacidosis at 6 and 16 weeks of age. Both had reduced consciousness, seizures and required intensive care for cerebral oedema. They subsequently developed spastic tetraplegia. Neurological examination in adulthood confirmed spastic tetraplegia and severe disability. Case 1 is wheelchair-bound and needs assistance for transfers, washing and dressing, whereas case 2 requires institutional care for all activities of daily living. Both cases have first-degree relatives with the same mutation with diabetes, who did not have ketoacidosis at diagnosis and do not have neurological disability. DISCUSSION: Ketoacidosis-related cerebral oedema at diagnosis in neonatal diabetes can cause long-term severe neurological disability. This will give additional neurological features to those directly caused by the genetic aetiology of the neonatal diabetes. Our cases highlight the need for increased awareness of neonatal diabetes and earlier and better initial treatment of the severe hyperglycaemia and ketoacidosis often seen at diagnosis of these children.

The radiological diagnosis of frontotemporal dementia in everyday practice: an audit of reports, review of diagnostic criteria, and proposal for service improvement.

AIM: To investigate how commonly valuable diagnostic information regarding the frontotemporal dementias (FTDs) may be missed on routine radiological reporting. MATERIALS AND METHODS: The magnetic resonance imaging (MRI) examination results of a series of 39 consecutive patients in whom the diagnosis was initially thought to be a form of FTD were audited. Twenty-two patients satisfied formal diagnostic criteria for subtypes of FTD. The initial non-specialist radiological reports of the MRI examinations were compared with those of a radiologist who specifically examined the images for the possibility of atypical dementia. RESULTS: Six of the 22 original reports provided a full and accurate description of the radiological findings, while two provided a fully accurate interpretation. CONCLUSION: Valuable diagnostic information may be missed unless clinicians and radiologists jointly review and discuss brain imaging in cases of dementia. The use of standardised scales may enhance the reporting of MRI examinations for dementia.

The neural correlates of everyday recognition memory.

We used a novel automatic camera, SenseCam, to create a recognition memory test for real-life events. Adapting a 'Remember/Know' paradigm, we asked healthy undergraduates, who wore SenseCam for 2 days, in their everyday environments, to classify images as strongly or weakly remembered, strongly or weakly familiar or novel, while brain activation was recorded with functional MRI. Overlapping, widely distributed sets of brain regions were activated by recollected and familiar stimuli. Within the medial temporal lobes, 'Remember' responses specifically elicited greater activity in the right anterior and posterior parahippocampal gyrus than 'Know' responses. 'New' responses activated anterior parahippocampal regions. A parametric analysis, across correctly recognised items, revealed increasing activation in the right hippocampus and posterior parahippocampal gyrus (pPHG). This may reflect modulation of these regions by the degree of recollection or, alternatively, by increasing memory strength. Strong recollection elicited greater activity in the left posterior hippocampus/pPHG than weak recollection indicating that this region is specifically modulated by the degree of recollection.

An fMRI study of long-term everyday memory using SenseCam.

We used a novel automatic camera, SenseCam, to investigate recognition memory for real-life events at a 5-month retention interval. Using fMRI we assessed recollection and familiarity memory using the remember/know procedure. Recollection evoked no medial temporal lobe (MTL) activation compared to familiarity and new responses. Instead, recollection activated diverse regions in neocortex including medial prefrontal cortex. We observed decreased activation in anterior hippocampus/ anterior parahippocampal gyrus (aPHG) at 5 months compared to a 36-hour retention interval. Familiarity was associated with greater activation in aPHG and posterior parahippocampal gyrus (pPHG) than recollection and new responses. Familiarity activation decreased over time in anterior hippocampus/aPHG and posterior hippocampus/pPHG. The engagement of neocortical regions such as medial prefrontal cortex at a 5-month delay, together with the reduced MTL activation at 5 months relative to at 36 hours is in line with the assumptions of Consolidation theory. SenseCam provides a valuable technique for assessing the processes that underlie remote everyday recognition memory.

Accelerated forgetting of real-life events in Transient Epileptic Amnesia.

Transient Epileptic Amnesia (TEA) is a form of temporal lobe epilepsy associated with ictal and interictal memory disturbance. Some patients with TEA exhibit Accelerated Long-term Forgetting (ALF), in which memory for verbal and non-verbal material is retained normally over short delays but fades at an unusually rapid rate over days to weeks. This study addresses three questions about ALF in TEA: (i) whether real-life events undergo ALF in a similar fashion to laboratory-based stimuli; (ii) whether ALF can be detected within 24h; (iii) whether procedural memories are susceptible to ALF. Eleven patients with TEA and eleven matched healthy controls wore a novel, automatic camera, SenseCam, while visiting a local attraction. Memory for images of events was assessed on the same day and after delays of one day, one week, and three weeks. Forgetting of real-life events was compared with forgetting of a word list and with performance on a procedural memory task. On the day of their excursion, patients and controls recalled similar numbers of primary events, associated secondary details (contiguous events, thoughts and sensory information) and items from the word list. In contrast, patients showed ALF for primary events over three weeks, with ALF for contiguous events, thoughts and words over the first day. Retention on the procedural memory task was normal over three weeks. The results indicate that accelerated forgetting in TEA: (i) affects memory for real-life events as well as laboratory stimuli; (ii) is maximal over the first day; and (iii) is specific to declarative memories.

When a patient with epilepsy complains about poor memory.

Patients with epilepsy often complain of "poor memory". The first step in managing this complaint is a clinical evaluation to define and, if possible, quantify the problem. The memory difficulty may be entirely unconnected to the epilepsy. But if the two appear to be linked, establish whether the memory problem is due to the seizures themselves, the pathology that underlies the seizures, their treatment, or their psychological sequelae such as anxiety or depression. Further management depends on the cause, while practical advice on the amelioration of poor memory can be useful.

Transient epileptic amnesia: regional brain atrophy and its relationship to memory deficits.

Transient epileptic amnesia (TEA) is a recently recognised form of epilepsy of which the principle manifestation is recurrent, transient episodes of isolated memory loss. In addition to the amnesic episodes, many patients describe significant interictal memory difficulties. Performance on standard neuropsychological tests is often normal. However, two unusual forms of memory deficit have recently been demonstrated in TEA: (i) accelerated long-term forgetting (ALF): the excessively rapid loss of newly acquired memories over a period of days or weeks and (ii) remote autobiographical memory loss: a loss of memories for salient, personally experienced events of the past few decades. The neuroanatomical bases of TEA and its associated memory deficits are unknown. In this study, we first assessed the relationship between subjective and objective memory performance in 41 patients with TEA. We then analysed MRI data from these patients and 20 matched healthy controls, using manual volumetry and voxel-based morphometry (VBM) to correlate regional brain volumes with clinical and neuropsychological data. Subjective memory estimates were unrelated to performance on standard neuropsychological tests but were partially predicted by mood, ALF and remote autobiographical memory. Manual volumetry identified subtle hippocampal volume loss in the patient group. Both manual volumetry and VBM revealed correlations between medial temporal lobe atrophy and standard anterograde memory scores, but no relation between atrophy and ALF or remote autobiographical memory. These results add weight to the hypothesis that TEA is a syndrome of mesial temporal lobe epilepsy. Furthermore, they suggest that although standard anterograde memory test performance is related to the degree of mesial temporal lobe damage, this is not true for ALF and autobiographical amnesia. It is possible that these unusual memory deficits have a more diffuse physiological basis rather than being a consequence of discrete structural damage.

Recent insights into the impairment of memory in epilepsy: transient epileptic amnesia, accelerated long-term forgetting and remote memory impairment.

Complaints of memory difficulties are common among patients with epilepsy, particularly with temporal lobe epilepsy where memory-related brain structures are directly involved by seizure activity. However, the reason for these complaints is often unclear and patients frequently perform normally on standard neuropsychological tests of memory. In this article, we review the literature on three recently described and interrelated forms of memory impairment associated with epilepsy: (i) transient epileptic amnesia, in which the sole or main manifestation of seizures is recurrent episodes of amnesia; (ii) accelerated long-term forgetting, in which newly acquired memories fade over days to weeks and (iii) remote memory impairment, in which there is loss of memories for personal or public facts or events from the distant past. Accelerated long-term forgetting and remote memory impairment are common amongst patients with transient epileptic amnesia, but have been reported in other forms of epilepsy. Their presence goes undetected by standard memory tests and yet they can have a profound impact on patients' lives. They pose challenges to current theoretical models of memory. We discuss the evidence for each of these phenomena, as well as their possible pathophysiological bases, methodological difficulties in their investigation and their theoretical implications.

Spinocerebellar ataxia type 8 in Scotland: frequency, neurological, neuropsychological and neuropsychiatric findings.

OBJECTIVES: The objectives of this study were to: (i) establish whether the spinocerebellar ataxia type 8 (SCA 8) expansion is associated with ataxia in Scotland; (ii) test the hypothesis that SCA 8 is associated with neuropsychological impairment; and (iii) review neuroradiological findings in SCA 8. METHODS: The methods included: (i) measurement of SCA 8 expansion frequencies in ataxic patients and healthy controls; (ii) comprehensive neuropsychological assessment of patients with SCA 8 and matched controls, neuropsychiatric interview; and (iii) comparison of patient and matched control magnetic resonance imaging (MRI) scans. RESULTS: (i) 10/694 (1.4%) unrelated individuals with ataxia had combined CTA/CTG repeat expansions >100 compared to 1/1190 (0.08%) healthy controls (P < 0.0005); (ii) neuropsychological assessment revealed a dysexecutive syndrome among SCA 8 patients, not readily explained by motor or mood disturbance; neuropsychiatric symptoms occurred commonly; (iii) cerebellar atrophy was the only salient MRI abnormality in the patient group. CONCLUSIONS: The SCA 8 expansion is associated with ataxia in Scotland. The disorder is associated with a dysexecutive syndrome.

Autobiographical amnesia and accelerated forgetting in transient epileptic amnesia.

BACKGROUND: Recurrent brief isolated episodes of amnesia associated with epileptiform discharges on EEG recordings have been interpreted as a distinct entity termed transient epileptic amnesia (TEA). Patients with TEA often complain of autobiographical amnesia for recent and remote events, but show normal anterograde memory. OBJECTIVE: To investigate (a) accelerated long term forgetting and (b) autobiographical memory in a group of patients with TEA. METHODS: Seven patients with TEA and seven age matched controls were evaluated on a range of anterograde memory tasks in two sessions separated by 6 weeks and by the Galton-Crovitz test of cued autobiographical memory. RESULTS: Patients with TEA showed abnormal long term forgetting of verbal material, with virtually no recall after 6 weeks. In addition, there was impaired recall of autobiographical memories from the time periods 1985-89 and 1990-94 but not from 1995-1999. CONCLUSIONS: TEA is associated with accelerated loss of new information and impaired remote autobiographical memory. There are a number of possible explanations including ongoing subclinical ictal activity, medial temporal lobe damage as a result of seizure, or subtle ischaemic pathology. Future analyses should seek to clarify the relationship between aetiology, seizure frequency, and degree of memory impairment.

Spinocerebellar ataxia type 8 in Scotland: genetic and clinical features in seven unrelated cases and a review of published reports.

OBJECTIVES: To establish whether the DNA expansion linked to spinocerebellar ataxia type 8 (SCA 8) is associated with ataxia in Scotland; to clarify the range of associated clinical phenotypes; and to compare the findings with previous reports. METHODS: DNA was screened from 1190 anonymised controls, 137 subjects who had tested negative for Huntington's disease, 176 with schizophrenia, and 173 with undiagnosed ataxia. Five unrelated ataxic patients with the SCA 8 expansion and a sixth identified subsequently had clinical and psychometric assessment; the clinical features were available in a seventh. A systematic search for other reports of SCA 8 was undertaken. RESULTS: Over 98% of SCA 8 CTA/CTG repeat lengths fell between 14 and 40. Repeat lengths over 91 were observed in three healthy controls (0.12%), two patients with suspected Huntington's disease (0.73%), and six ataxic subjects (1.74%; p<0.0005 v healthy controls). Repeat lengths over 100 occurred in five ataxic subjects but in only one control. All seven symptomatic subjects with the SCA 8 expansion had a cerebellar syndrome; four had upper motor neurone signs; and 5/6 assessed had cognitive complaints. There was personality change in two and mood disturbance in three. In published reports, SCA 8 repeat lengths over 91 occurred in approximately 0.5% of the healthy population but were over-represented among ataxic patients (3.4%; p<0.0001). The predominant clinical phenotype was cerebellar, with pyramidal signs in 50%, and neuropsychiatric features in some cases. CONCLUSIONS: SCA 8 expansion is a risk factor for a cerebellar syndrome, often associated with upper motor neurone and neuropsychiatric features. The expansion occurs unexpectedly often in the general population.

Functional weakness and sensory disturbance.

In the diagnosis of functional weakness and sensory disturbance, positive physical signs are as important as absence of signs of disease. Motor signs, particularly Hoover's sign, are more reliable than sensory signs, but none should be used in isolation and must be interpreted in the overall context of the presentation. It should be borne in mind that a patient may have both a functional and an organic disorder.

Consciousness.

Consciousness is topical, for reasons including its renewed respectability among psychologists, rapid progress in the neuroscience of perception, memory and action, advances in artificial intelligence and dissatisfaction with the dualistic separation of mind and body. Consciousness is an ambiguous term. It can refer to (i) the waking state; (ii) experience; and (iii) the possession of any mental state. Self-consciousness is equally ambiguous, with senses including (i) proneness to embarrassment in social settings; (ii) the ability to detect our own sensations and recall our recent actions; (iii) self-recognition; (iv) the awareness of awareness; and (v) self-knowledge in the broadest sense. The understanding of states of consciousness has been transformed by the delineation of their electrical correlates, of structures in brainstem and diencephalon which regulate the sleep-wake cycle, and of these structures' cellular physiology and regional pharmacology. Clinical studies have defined pathologies of wakefulness: coma, the persistent vegetative state, the 'locked-in' syndrome, akinetic mutism and brain death. Interest in the neural basis of perceptual awareness has focused on vision. Increasingly detailed neuronal correlates of real and illusory visual experience are being defined. Experiments exploiting circumstances in which visual experience changes while external stimulation is held constant are tightening the experimental link between consciousness and its neural correlates. Work on unconscious neural processes provides a complementary approach. 'Unperceived' stimuli have detectable effects on neural events and subsequent action in a range of circumstances: blindsight provides the classical example. Other areas of cognitive neuroscience also promise experimental insights into consciousness, in particular the distinctions between implicit and explicit memory and deliberate and automatic action. Overarching scientific theories of consciousness include neurobiological accounts which specify anatomical or physiological mechanisms for awareness, theories focusing on the role played by conscious processes in information processing and theories envisaging the functions of consciousness in a social context. Whether scientific observation and theory will yield a complete account of consciousness remains a live issue. Physicalism, functionalism, property dualism and dual aspect theories attempt to do justice to three central, but controversial, intuitions about experience: that it is a robust phenomenon which calls for explanation, that it is intimately related to the activity of the brain and that it has an important influence on behaviour.

Focal autobiographical amnesia in association with transient epileptic amnesia.

Although problems with remembering significant events from the past (e.g. holidays, weddings, etc.) have been reported previously in patients with transient epileptic amnesia (TEA), to date there have been no detailed studies of autobiographical memory in patients with this disorder. To investigate this issue, a 68-year-old right-handed man (R.G.) who suffered from TEA and reported significant autobiographical memory problems was tested on a battery of neuropsychological tests of anterograde and remote memory. Tests of autobiographical memory revealed that R.G. was unable to evoke detailed autobiographical recollections from a substantial part of his life. By contrast, he performed well on tests of new learning and general knowledge and possessed good personal semantic information about his past. In summary, a distinct form of autobiographical amnesia, which is characterized by loss of experiential remembering of significant events, may be associated with TEA. It is proposed that the autobiographical memory deficit seen in the disorder may result from the progressive erasure of cortically based memory representations. This case adds to growing evidence for a dissociation between mechanisms subserving anterograde memory and those required to evoke remote episodic memories.