Masud Husain FMedSci [1] is a clinical neurologist and neuroscientist working in the UK. He is Professor of Neurology & Cognitive Neuroscience at the Nuffield Department of Clinical Neurosciences [2] and Departmental of Experimental Psychology, [3] University of Oxford, a Professorial Fellow at New College, Oxford, [4] and Editor-in-Chief of the journal Brain [5] . He was born in East Pakistan (now Bangladesh).
Husain was educated at King Edward VI Camp Hill School for Boys, Birmingham, and studied Physiological Sciences (Medicine) at New College, Oxford, [4] before completing his Doctor of Philosophy degree at Christ Church, Oxford, where he was a Senior Scholar. He held a Harkness Fellowship while a postdoctoral fellow in the laboratory of Richard A. Andersen at MIT. [6] Husain completed his clinical and neurological training at hospitals in Oxford and London. [2]
Husain's research focuses on cognitive functions in people with neurological diseases and healthy people. [7] [8] [9] [10] [11] [12] [13] [14] [15]
His work on people with hemispatial neglect following stroke demonstrated several novel components of this syndrome. Using the attentional blink paradigm he showed that there were non-spatial, selective attention deficits in these patients, [16] in addition to their well-established directional attentional bias. Subsequent behavioural studies revealed that some people with hemispatial neglect can also suffer from impaired spatial working memory, [17] often revisiting locations without being aware that they have fixated them before. [18] [19] Some may have poor sustained attention as measured on vigilance tasks, [20] or even directional motor deficits as indexed by paradigms where the spatial location of a visual target is dissociated from direction of movement required to reach it. [21] [22] These findings provided further evidence for neglect being a multi-component syndrome, with different patients having different deficits, depending upon the extent of their lesion. [23] [24] Critical brain regions associated with neglect that were identified by this work, included the right inferior posterior parietal and frontal regions. [25] [26] Experimental medicine studies by Husain's group using the dopamine agonist rotigotine [27] and the noradrenergic agonist guanfacine [28] [29] demonstrated that these drugs can ameliorate hemispatial neglect to some extent by improving attention.
By using new methods to measure the precision of recall in healthy people, work in Husain's lab challenged the view that capacity of visual short-term memory or working memory is limited to a fixed number of items. [30] [31] Instead, this research revealed that although short-term memory is a highly limited resource, it can be flexibly deployed depending upon task demands. [32] This work led to the application of new methods to measure short-term memory in patients with Alzheimer's disease, [33] [34] Parkinson's disease [33] [34] [35] and individuals at risk of developing these conditions. [33] [34] [35] [36] The techniques that have been developed can provide more sensitive ways to measure short-term memory than traditional methods. [37] They have also revealed how different mechanisms might underlie short-term memory disorders in different neurological conditions. [34]
Work from Husain's lab showed that lesions to ventral basal ganglia leads to a condition of profound apathy, manifest as a lack of motivation to initiate action and specifically attributable to a deficit in reward sensitivity. [38] Using the dopamine receptor agonist ropinirole, it was possible to improve reward sensitivity, restore motivational vigour and reverse apathy. [38] These observations stimulated larger-scale studies in Parkinson's disease, a condition associated with basal ganglia pathology and often debilitating apathy. The syndrome of pathological apathy in Parkinson's disease [39] [40] and small vessel cerebrovascular disease [41] [42] was found to be characterised by reduced sensitivity to rewards, a deficit that could be ameliorated by dopaminergic drugs in Parkinson's disease. [39] [40] This has led to a theoretical framework to understand mechanisms underlying apathy across brain disorders which incorporates concepts from cost-benefit decision making to formalise how people differ in their willingness to engage in effort in order to obtain potential rewards. [43]
The basal ganglia are considered to be essential for linking motivation to action systems. [44] Outputs of the basal ganglia are strongly connected to medial frontal cortex. Husain's group identified a mechanism that resolves competition between conflicting action plans, in medial frontal brain regions, including the supplementary eye field, [45] supplementary motor area and pre-supplementary motor area. [46] [47] A key component of voluntary control paradoxically appears to involve inhibition of unwanted actions that are primed automatically by seeing objects around us. [48] This control is lost following supplementary motor area and pre-supplementary motor area lesions. Findings from lesion, stimulation and physiological studies were incorporated to provide a new theoretical framework for the role of the supplementary motor area and pre-supplementary motor area complex. [49]
Husain held a Wellcome Trust Senior Research Fellowship at Imperial College London (2000-2007) and University College London, UCL (2007–12). He was awarded a Wellcome Trust Principal Research Fellowship (2012-2023) and elected Fellow of the UK Academy of Medical Sciences (2008). [1] Husain won the Royal College of Physicians' (London) Graham Bull Prize in Clinical Science (2006), British Neuropsychological Society's Elizabeth Warrington Prize (2006), [50] and the European Academy of Neurology Investigator Award (2016). [51] He is Fellow of the American Academy of Neurology (2018) and Fellow of the European Academy of Neurology (2018), [52] and is co-lead of the NIHR Oxford Health Biomedical Research Centre Dementia theme (2022 -) [53] and Dementia Research Oxford at the University of Oxford [54]
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of neural integration in the central nervous system. and plays a key role in attention, perception, awareness, thought, memory, language, and consciousness. The cerebral cortex is part of the brain responsible for cognition.
The basal ganglia (BG) or basal nuclei are a group of subcortical nuclei found in the brains of vertebrates. In humans and other primates, differences exist, primarily in the division of the globus pallidus into external and internal regions, and in the division of the striatum. Positioned at the base of the forebrain and the top of the midbrain, they have strong connections with the cerebral cortex, thalamus, brainstem and other brain areas. The basal ganglia are associated with a variety of functions, including regulating voluntary motor movements, procedural learning, habit formation, conditional learning, eye movements, cognition, and emotion.
Apathy is a lack of feeling, emotion, interest, or concern about something. It is a state of indifference, or the suppression of emotions such as concern, excitement, motivation, or passion. An apathetic individual has an absence of interest in or concern about emotional, social, spiritual, philosophical, virtual, or physical life and the world. Apathy can also be defined as a person's lack of goal orientation. Apathy falls in the less extreme spectrum of diminished motivation, with abulia in the middle and akinetic mutism being more extreme than both apathy and abulia.
The caudate nucleus is one of the structures that make up the corpus striatum, which is a component of the basal ganglia in the human brain. While the caudate nucleus has long been associated with motor processes due to its role in Parkinson's disease, it plays important roles in various other nonmotor functions as well, including procedural learning, associative learning and inhibitory control of action, among other functions. The caudate is also one of the brain structures which compose the reward system and functions as part of the cortico–basal ganglia–thalamic loop.
The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.
The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain.
Anosognosia is a condition in which a person with a disability is cognitively unaware of having it due to an underlying physical condition. Anosognosia results from physiological damage to brain structures, typically to the parietal lobe or a diffuse lesion on the fronto-temporal-parietal area in the right hemisphere, and is thus a neuropsychiatric disorder. A deficit of self-awareness, the term was first coined by the neurologist Joseph Babinski in 1914, in order to describe the unawareness of hemiplegia.
Frontotemporal dementia (FTD), frontotemporal degeneration disease, or frontotemporal neurocognitive disorder encompasses several types of dementia involving the progressive degeneration of the brain's frontal and temporal lobes. FTDs broadly present as behavioral or language disorders with gradual onsets.
Hemispatial neglect is a neuropsychological condition in which, after damage to one hemisphere of the brain, a deficit in attention and awareness towards the side of space opposite brain damage is observed. It is defined by the inability of a person to process and perceive stimuli towards the contralesional side of the body or environment. Hemispatial neglect is very commonly contralateral to the damaged hemisphere, but instances of ipsilesional neglect have been reported.
Hypokinesia is one of the classifications of movement disorders, and refers to decreased bodily movement. Hypokinesia is characterized by a partial or complete loss of muscle movement due to a disruption in the basal ganglia. Hypokinesia is a symptom of Parkinson's disease shown as muscle rigidity and an inability to produce movement. It is also associated with mental health disorders and prolonged inactivity due to illness, amongst other diseases.
Frontal lobe disorder, also frontal lobe syndrome, is an impairment of the frontal lobe of the brain due to disease or frontal lobe injury. The frontal lobe plays a key role in executive functions such as motivation, planning, social behaviour, and speech production. Frontal lobe syndrome can be caused by a range of conditions including head trauma, tumours, neurodegenerative diseases, neurodevelopmental disorders, neurosurgery and cerebrovascular disease. Frontal lobe impairment can be detected by recognition of typical signs and symptoms, use of simple screening tests, and specialist neurological testing.
The posterior cingulate cortex (PCC) is the caudal part of the cingulate cortex, located posterior to the anterior cingulate cortex. This is the upper part of the "limbic lobe". The cingulate cortex is made up of an area around the midline of the brain. Surrounding areas include the retrosplenial cortex and the precuneus.
Frontostriatal circuits are neural pathways that connect frontal lobe regions with the striatum and mediate motor, cognitive, and behavioural functions within the brain. They receive inputs from dopaminergic, serotonergic, noradrenergic, and cholinergic cell groups that modulate information processing. Frontostriatal circuits are part of the executive functions. Executive functions include the following: selection and perception of important information, manipulation of information in working memory, planning and organization, behavioral control, adaptation to changes, and decision making. These circuits are involved in neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease as well as neuropsychiatric disorders including schizophrenia, depression, obsessive compulsive disorder (OCD), and in neurodevelopmental disorder such as attention-deficit hyperactivity disorder (ADHD).
The posterior parietal cortex plays an important role in planned movements, spatial reasoning, and attention.
The neuroanatomy of memory encompasses a wide variety of anatomical structures in the brain.
Constructional apraxia is a neurological disorder in which people are unable to perform tasks or movements even though they understand the task, are willing to complete it, and have the physical ability to perform the movements. It is characterized by an inability or difficulty to build, assemble, or draw objects. Constructional apraxia may be caused by lesions in the parietal lobe following stroke or it may serve as an indicator for Alzheimer's disease.
The temporal dynamics of music and language describes how the brain coordinates its different regions to process musical and vocal sounds. Both music and language feature rhythmic and melodic structure. Both employ a finite set of basic elements that are combined in ordered ways to create complete musical or lingual ideas.
The neuroscience of aging is the study of the changes in the nervous system that occur with ageing. Aging is associated with many changes in the central nervous system, such as mild atrophy of the cortex that is considered non-pathological. Aging is also associated with many neurological and neurodegenerative disease such as amyotrophic lateral sclerosis, dementia, mild cognitive impairment, Parkinson's disease, and Creutzfeldt–Jakob disease.
The cortico-basal ganglia-thalamo-cortical loop is a system of neural circuits in the brain. The loop involves connections between the cortex, the basal ganglia, the thalamus, and back to the cortex. It is of particular relevance to hyperkinetic and hypokinetic movement disorders, such as Parkinson's disease and Huntington's disease, as well as to mental disorders of control, such as attention deficit hyperactivity disorder (ADHD), obsessive–compulsive disorder (OCD), and Tourette syndrome.
Dyschiria, also known as dyschiric syndrome, is a neurological disorder where one-half of an individual's body or space cannot be recognized or respond to sensations. The term dyschiria is rarely used in modern scientific research and literature. Dyschiria has been often referred to as unilateral neglect, visuo-spatial neglect, or hemispatial neglect from the 20th century onwards. Psychologists formerly characterized dyschiric patients to be unable to discriminate or report external stimuli. This left the patients incapable of orienting sensory responses in their extrapersonal and personal space. Patients with dyschiria are unable to distinguish one side of their body in general, or specific segments of the body. There are three stages to dyschiria: achiria, allochiria, and synchiria, in which manifestations of dyschiria evolve in varying degrees.