Helping You Find Full Text Journal Articles

Search Results:

Author: John L Bradshaw (136)


Aug
2017

Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder with subtle impact on cognition. Inhibitory processes and cognitive flexibility were examined in FRDA by assessing the ability to suppress a predictable verbal response. We administered the Hayling Sentence Completion Test (HSCT), the Trail Making Test, and the Stroop Test to 43 individuals with FRDA and 42 gender- and age-matched control participants.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

While Major Depressive Disorder (MDD) is primarily characterized by mood disturbances, impaired attentional control is increasingly identified as a critical feature of depression. Deep transcranial magnetic stimulation (deepTMS), a noninvasive neuromodulatory technique, can modulate neural activity and induce neuroplasticity changes in brain regions recruited by attentional processes. This study examined whether acute and long-term high-frequency repetitive deepTMS to the dorsolateral prefrontal cortex (DLPFC) can attenuate attentional deficits associated with MDD.

View Full Text PDF Listings View primary source full text article PDFs.

Aug
2015

Although the experience of vicarious sensations when observing another in pain have been described postamputation, the underlying mechanisms are unknown. We investigated whether vicarious sensations are related to posttraumatic stress disorder (PTSD) symptoms and chronic pain. In Study 1, 236 amputees completed questionnaires about phantom limb phenomena and vicarious sensations to both innocuous and painful sensory experiences of others.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Preclinical studies suggest that cortical alterations within the prefrontal cortex (PFC) are critical to the pathophysiology of alcohol dependence. Combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG) allows direct assessment of cortical excitability and inhibition within the PFC of human subjects. We report the first application of TMS-EEG to measure these indices within the PFC of alcohol-dependent (ALD) patients post-detoxification.

View Full Text PDF Listings View primary source full text article PDFs.

Jun
2015

To determine the extent and nature of driving self-regulation in drivers with Parkinson disease (PD) and factors associated with self-regulatory practices.
Although people with PD have consistently been shown to have driving impairments, few studies have examined self-regulatory driving practices and their relationship to driving performance.
We used a self-report driving questionnaire to examine driving self-regulation in 37 drivers with PD and 37 healthy age-matched controls.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2015

Recent studies in young adult females with the fragile X mental retardation 1 (FMR1) gene premutation (PM) have shown subtle but significant impairments in executive control and postural stability. Less is known about the influence of age and FMR1 gene expression on executive control and postural stability in females with the PM. Here, we examined the attentional demands of reactive stepping using a well-validated measure of choice stepping reaction time under dual-task interference.

View Full Text PDF Listings View primary source full text article PDFs.

Sep
2014

We sought to quantify subtle changes in motor control in multiple sclerosis (MS) using a Fitts law reciprocal aiming task presented on a computer touchscreen.
Upper-limb motor control is impaired in MS. However, many commonly used motor assessments do not detect subtle changes in motor function or differentiate between aspects of movement such as planning and online control.

View Full Text PDF Listings View primary source full text article PDFs.

Aug
2014

This study aimed to compare the gait of children with ADHD - Combined Type (ADHD-CT) to typically developing (TD) children. Children with ADHD-CT (n=14; mean age 10 years 4 months) and a TD group (n=13; mean age 10 years 9 months) walked at self-selected slow, preferred and fast speed on an electronic walkway system. Participants completed a total of 15 walking trials; 5 trials per walking condition.

View Full Text PDF Listings View primary source full text article PDFs.

Sep
2014

Recent studies report a higher risk of dementia and motor symptoms in females with the fragile X mental retardation 1 premutation (PM-carriers) than has hitherto been appreciated. Here, we use dual-task gait paradigms to identify potential markers of cognitive and motor decline in female PM-carriers. Spatiotemporal gait characteristics and variability of gait were assessed during single- and dual-task conditions in 28 female PM-carriers (mean age 41.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Impulsivity is considered a core feature of problem gambling; however, self-reported impulsivity and inhibitory control may reflect disparate constructs. We examined self-reported impulsivity and inhibitory control in 39 treatment-seeking problem gamblers and 41 matched controls using a range of self-report questionnaires and laboratory inhibitory control tasks. We also investigated differences between treatment-seeking problem gamblers who prefer strategic (e.

View Full Text PDF Listings View primary source full text article PDFs.

Jul
2014

To analyse problem gamblers' decision-making under conditions of risk and ambiguity, investigate underlying psychological factors associated with their choice behaviour and examine whether decision-making differed in strategic (e.g., sports betting) and non-strategic (e.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2014

There is evidence which demonstrates that a subset of males with a premutation CGG repeat expansion (between 55 and 200 repeats) of the fragile X mental retardation 1 gene exhibit subtle deficits of executive function that progressively deteriorate with increasing age and CGG repeat length. However, it remains unclear whether similar deficits, which may indicate the onset of more severe degeneration, are evident in female PM-carriers. In the present study we explore whether female PM-carriers exhibit deficits of executive function which parallel those of male PM-carriers.

View Full Text PDF Listings View primary source full text article PDFs.

Feb
2014

Alcohol dependence, a chronic relapsing disorder, is characterized by an impaired ability to regulate compulsive urges to consume alcohol. Very few empirical studies have examined the presence of these executive deficits, how they relate to craving, and the enduring nature of these deficits during abstinence. As such, the current study aimed to characterize these cognitive deficits within a sample of 24 alcohol-dependent participants post-detoxification and 23 non-alcohol-dependent participants.

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2014

Fragile X Mental Retardation 1 (FMR1) premutation carriers (PM-carriers) have a defective trinucleotide expansion on the FMR1 gene that is associated with continuum of neuropsychological and mental disorders. Currently, little is known about the distinct subcomponents of executive function potentially impaired in female PM-carriers, and there have been no investigations into associations between executive function and incidences of mental disorders. A total of 35 female PM-carriers confirmed by Asuragen triple primed PCR DNA testing and 35 age- and intelligence-matched controls completed tests of executive function (i.

View Full Text PDF Listings View primary source full text article PDFs.

Apr
2014

Atrophy of the dentate nucleus is one of the major neuropathological changes in Friedreich ataxia (FRDA). Neuroimaging studies demonstrated white matter (WM) degeneration in FRDA. In this study, we used advanced tractography techniques to quantitatively measure WM changes in the dentato-thalamic and dentato-rubral tracts, and correlated these changes with cognitive profiles of FRDA.

View Full Text PDF Listings View primary source full text article PDFs.

Sep
2013

Recent investigations report a higher risk of motor symptoms in females with the FMR1 premutation (PM-carriers) than has hitherto been appreciated. Here we examined basic sensorimotor and postural control under different sensory and attentional dual-task demands. Physiological performance and postural sway measures from the Physiological Profile Assessment (Lord et al.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Motor overflow is overt involuntary movement that accompanies voluntary movement. This study investigated the change in overflow production across a timed trial and the factors that affected this profile. Seventeen children (aged 8-11 years), 17 young adults (aged 18-35 years), and 17 older adults (aged 60-80 years) performed a 5-s finger pressing task by exerting 33% or 66% of their maximal force output using either index finger.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

The mirror neuron hypothesis of autism is highly controversial, in part because there are conflicting reports as to whether putative indices of mirror system activity are actually deficient in autism spectrum disorder (ASD). Recent evidence suggests that a typical putative mirror system response may be seen in people with an ASD when there is a degree of social relevance to the visual stimuli used to elicit that response. Individuals with ASD (n = 32) and matched neurotypical controls (n = 32) completed a transcranial magnetic stimulation (TMS) experiment in which the left primary motor cortex (M1) was stimulated during the observation of static hands, individual (i.

View Full Text PDF Listings View primary source full text article PDFs.

May
2014

Brain pathology in Friedreich ataxia is characterized by progressive degeneration of nervous tissue in the brainstem, cerebellum and cerebellar peduncles. Evidence of cerebral involvement is however equivocal. This brain imaging study investigates cerebello-cerebral white matter connectivity in Friedreich ataxia with diffusion MRI and tractography performed in 13 individuals homozygous for a GAA expansion in intron one of the frataxin gene and 14 age- and gender-matched control participants.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2013

For years, premutation-carriers of fragile X-syndrome (FXS) were assumed free from any deleterious phenotype. In this review, we discuss the current literature on neurocognitive, emotional and neuromotor profiles emerging in females with the fragile-X premutation, and discuss phenotypic profiles in male premutation-carriers to gain insights into possible underlying mechanisms associated with FMR1 gene expression. We contend that this emerging phenotypic profile in females with the fragile-X premutation needs further investigation using experimentally-driven tasks sensitive to neural networks especially vulnerable to FMR1 gene expression.

View Full Text PDF Listings View primary source full text article PDFs.

Jun
2013

Motor proficiency was investigated in a sample of children with Attention Deficit Hyperactivity Disorder-Combined type (ADHD-CT) without autism. Accounting for the influence of co-morbid autistic symptoms in ADHD motor studies is vital given that motor impairment has been linked to social-communication symptoms in children who have co-morbid ADHD and autistic-like symptoms. Two groups of children aged between 7-14 years were recruited; children with ADHD-CT (n = 16; mean age 10 years, 7 months [SD = 1 year, 10 months]) and a typically developing (n = 16; mean age 10 years, 6 months [SD = 2 years, 6 months]) group.

View Full Text PDF Listings View primary source full text article PDFs.

Nov
2012

'Mirror pain' describes when the observation of another's pain experience induces a personal experience of pain. It has been suggested that mirror pain could result from changes in neural excitability or inhibition. In this study we used transcranial magnetic stimulation (TMS) to investigate motor cortical excitability in lower-limb amputees who experience mirror pain.

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2015

This study investigated the relationship between motor performance and social-communicative impairment in children with ADHD-combined type (ADHD-CT).
An upper limb Fitts' aiming task was used as a measure of motor performance and the Social Responsiveness Scale as a measure of social-communicative/autistic impairment in the following groups: ADHD-CT (n = 11) and typically developing (TD) controls (n = 10).
Children with ADHD-CT displayed greater variability in their movements, reflected in increased error variance over repeated aiming trials compared with TD controls.

View Full Text PDF Listings View primary source full text article PDFs.

May
2013

Mounting evidence suggests a possible role for γ-aminobutyric acid (GABA) in the neuropathophysiology of autism spectrum disorders (ASD), but the extent of this impairment is unclear. A non-invasive, in vivo measure of GABA involves transcranial magnetic stimulation (TMS) of the primary motor cortex to probe cortical inhibition. Individuals diagnosed with ASD (high-functioning autism or Asperger's disorder) (n = 36 [28 male]; mean age: 26.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2012

Body incongruity in body integrity identity disorder (BIID) manifests in the desire to have a healthy limb amputated. We describe a variant of the disorder: the desire to become paralyzed (paralysis-BIID).
Sixteen otherwise healthy participants, recruited through Internet-based forums, websites, or word of mouth, completed questionnaires about details of their desire and accompanying symptoms.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2012

Impaired selective attention in Huntington disease (HD) may manifest as difficulty in identifying a single target embedded among a series of distractors in rapid serial visual presentation tasks.
We used an attentional blink (AB) paradigm to examine whether attentional control is impaired in symptomatic HD. Fourteen HD patients and 13 age-matched healthy controls performed a rapid serial visual presentation task in which 2 targets (T1 and T2) and numerous distractors were presented in rapid succession.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Friedreich ataxia (FRDA), the most common of the hereditary ataxias, is an autosomal recessive, multisystem disorder characterised by progressive ataxia, sensory symptoms, weakness, scoliosis and cardiomyopathy. FRDA is caused by a GAA expansion in intron one of the FXN gene, leading to reduced levels of the encoded protein frataxin, which is thought to regulate cellular iron homeostasis. The cerebellar and spinocerebellar dysfunction seen in FRDA has known effects on motor function; however until recently slowed information processing has been the main feature consistently reported by the limited studies addressing cognitive function in FRDA.

View Full Text PDF Listings View primary source full text article PDFs.

Jun
2012

Observing noxious injury to another's hand is known to induce corticospinal inhibition that can be measured in the observer's corresponding muscle. Here, we investigated whether acquired pain synesthetes, individuals who experience actual pain when observing injury to another, demonstrate less corticospinal inhibition than do controls during pain observation, as a potential mechanism for the experience of vicarious pain. We recorded motor-evoked potentials (MEPs) induced at two time points through transcranial magnetic stimulation while participants observed videos of a hand at rest, a hypodermic needle penetrating the skin, a Q-tip touching the skin, and a hypodermic needle penetrating an apple.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Stop task after-effects are behavioral consequences of response inhibition (i.e., slowed response time), and may index both behavioral control adjustments and repetition priming.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
2011

Body integrity identity disorder (BIID) is characterised by profound experience of incongruity between the biological and desired body structure. The condition manifests in "non-belonging" of body parts, and the subsequent desire to amputate, paralyse or disable a limb. Little is known about BIID; however, a neuropsychological model implicating right fronto-parietal and insular networks is emerging, with potential disruption to body representation.

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2012

Motor impairments are common in autism spectrum disorders (ASD). Electrophysiologic studies reveal abnormalities in the preparation of movement; repetitive transcranial magnetic stimulation (rTMS) to key motor cortical sites may therefore be a useful technique for improving motor function in ASD.
To examine whether rTMS can improve electrophysiologic and behavioral indices of motor activity.

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2012

Recent research suggests the observation or imagination of somatosensory stimulation in another (e.g., touch or pain) can induce a similar somatosensory experience in oneself.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2012

The neurobiology of autism spectrum disorder (ASD) is not particularly well understood, and biomedical treatment approaches are therefore extremely limited. A prominent explanatory model suggests that social-relating symptoms may arise from dysfunction within the mirror neuron system, while a recent neuroimaging study suggests that these impairments in ASD might reduce with age.
Participants with autism spectrum disorder (i.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

This study sought to investigate the impact of external cue validity on simulated driving performance in 19 Parkinson's disease (PD) patients and 19 healthy age-matched controls. Braking points and distance between deceleration point and braking point were analysed for red traffic signals preceded either by Valid Cues (correctly predicting signal), Invalid Cues (incorrectly predicting signal), and No Cues. Results showed that PD drivers braked significantly later and travelled significantly further between deceleration and braking points compared with controls for Invalid and No-Cue conditions.

View Full Text PDF Listings View primary source full text article PDFs.

Nov
2011

Although neuropsychological deficits in adult depression are relatively well established, findings in children/adolescents have been inconsistent and thus require further investigation. The current study investigated verbal fluency (VF), cognitive speed, motor speed, and executive functions in adolescents with unipolar depression. Results indicated that adolescents with minor depression showed working memory deficits and poorer VF (letter task).

View Full Text PDF Listings View primary source full text article PDFs.

May
2012

Autism and Asperger's disorder (AD) are characterised by impairments in social interaction, stereotypic behaviours or restricted interests. Although currently listed as distinct clinical disorders, the validity of their distinction remains controversial. This study examined gait in children with autism and AD.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
2011

Friedreich ataxia (FRDA) is the most common of the genetically inherited ataxias. We sought to examine motor planning ability in 13 individuals with FRDA and 13 age- and sex-matched control participants using two experimental paradigms that examined the ability to incorporate different levels of advance information to plan sequential movements. Individuals with FRDA demonstrated a differential pattern of motor response to advance information and were significantly disadvantaged by conditions requiring initiation of movement without a direct visual cue.

View Full Text PDF Listings View primary source full text article PDFs.

Aug
2011

Distinct cognitive and neural mechanisms underlie perception and action in near (within-reach) and far (outside-reach) space. Objects in far space can be brought into the brain's near-space through tool-use. We determined whether a near object can be pushed into far space by changing the pictorial context in which it occurs.

View Full Text PDF Listings View primary source full text article PDFs.

May
2011

We describe the case of a patient who experienced phantom pain that began 42 years after right above-the-knee amputation. Immediately prior to phantom pain onset, this long-term amputee had experienced, in rapid succession, cancer, hemicolectomy, chemotherapy, and thrombotic occlusion. Very little has been published to date on the association between chemotherapy and exacerbation of neuropathic pain in amputees, let alone the phenomenon of bringing about pain in amputees who have been pain-free for many decades.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2012

There are increasing reports of people experiencing pain when observing pain in another. This describes the phenomenon of synaesthetic pain which, until recently, had been primarily reported in amputees with phantom pain. In the current study, we used electroencephalography (EEG) to investigate how amputees who experience synaesthetic pain process pain observed in another.

View Full Text PDF Listings View primary source full text article PDFs.

Oct
2011

Phantom limb perception is common following amputation, and is sometimes characterised by pain that resembles the characteristics, intensity or location of past pain. We tested Flor's model that phantom pain results from memory for long-lasting znoxious input.
We report a questionnaire study of 283 amputees, that explored the experience of painful, non-painful and postural somatosensory memories in the phantom.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Motor overflow is involuntary overt movement or covert muscle activity that cooccurs with voluntary movement. Overflow is present in several pathological conditions, as well as in neurologically healthy children and older adults, and can be induced in healthy young adults under effortful conditions. This motor phenomenon may provide insight into the underlying mechanisms and kinetic characteristics of voluntary and involuntary motor control in various populations.

View Full Text PDF Listings View primary source full text article PDFs.

May
2011

The observation of other's behaviour results in increased corticospinal excitability (CSE) within the primary motor cortex, a phenomenon that has typically been interpreted in the context of motor resonance and human "mirror systems". Mirror systems are implicated in empathy, and may therefore show a preferential response to the observation of interactive behaviour. Participants were administered transcranial magnetic stimulation (TMS) to the primary motor cortex while viewing matched hand movements with or without (1) an interactive context and (2) an interactive context with an implied heightened emotional aspect.

View Full Text PDF Listings View primary source full text article PDFs.

View Full Text PDF Listings View primary source full text article PDFs.

Aug
2011

Phantom phenomena are frequent following amputation, but how this often painful experience is modified or triggered by spontaneous events or sensations often puzzles amputees and clinicians alike. We explored triggers of phantom phenomena in a heterogeneous sample of 264 upper and lower limb adult amputees with phantom sensations. Participants completed a structured questionnaire to determine the prevalence and nature of the triggers of phantom phenomena.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Pain synaesthetes experience pain in a presensitised region when observing or imagining another person in pain. We conducted an upper-limb embodiment study using a modified rubber-hand illusion in which lower-limb amputees originally participated as control subjects for the upper-limb amputees. While we found all subjects experienced topographic illusory sensations, we also serendipitously found that lower-limb amputee pain synaesthetes experienced pain or a motor response in their phantom leg when the embodied hand was threatened (e.

View Full Text PDF Listings View primary source full text article PDFs.

Feb
2011

Previous studies have reported that people with the neurodevelopmental disorder Williams syndrome exhibit difficulties with visuomotor control. In the current study, we examined the extent to which visuomotor deficits were associated with movement planning or feedback-based on-line control. We used a variant of the Fitts' reciprocal aiming task on a computerized touchscreen in adults with WS, IQ-matched individuals with Down syndrome (DS), and typically developing controls.

View Full Text PDF Listings View primary source full text article PDFs.

Apr
2011

The potential for the coexistence of the developmental disorders autism and attention-deficit/hyperactivity disorder (ADHD) in any one individual has for a long time been a contentious issue. While from a neurobiological perspective it is possible, and even highly likely, that ADHD and autism might clinically co-exist, our major diagnostic classification systems (DSM-IV-TR and ICD-10) currently preclude such a dual-diagnosis. The aim of the current review is to summarise current diagnostic criteria and treatment strategies for the two disorders, relevant theories of developmental dysfunction, and update the state of the debate regarding comorbidity.

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2011

Sustained volitional attention and working memory capacity was examined for the first time in people with Friedreich ataxia (FRDA). We administered subtests of the Test of Everyday Attention to 16 individuals with molecularly confirmed FRDA and gender-, age-, and IQ-matched controls. Clinically significant impairment in working memory and sustained volitional attention was evident.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
2010

Motor overflow refers to involuntary movement or muscle activity coinciding with voluntary movement. We examined whether 16 young adults (18-30 years) and 16 older adults (50-80 years) could voluntarily inhibit overflow. Participants performed a finger pressing task, exerting 50% of their maximal force.

View Full Text PDF Listings View primary source full text article PDFs.

Back to top