or mental abilities [28]. It is followed with lack of coordination and unsteady movement [29]. As the disease advances, uncoordinated, jerky body movements become more apparent [28]. The physical abilities gradually worsen until movement coordination becomes severe and the person is unable to walk [28, 29]. Mental abilities generally decline into dementia [30]. The specific symptoms vary somewhat between people [28]. The disease symptoms usually begin between 30 and 50 years of age but can start at any age [30, 31].
Idiopathic intracranial hypertension: a neurological condition of unknown cause, with symptoms very similar to those of a brain tumour, defined by increased intracranial pressure around the brain without the presence of tumour or disease.
Meningitis: an inflammation of the meninges (the protective membranes that cover the brain and spinal cord) caused by an infection. The inflammation can cause damage to the brain and spinal cord. Acute bacterial meningitis is rapidly developing inflammation of the tissue layers and of the fluid-filled space between the meninges (subarachnoid space) when it is caused by bacteria.
Migraine: affects approximately 15% of the population. It is a primary headache disorder characterised by recurrent headaches mostly severe [32]. Typically, the headaches affect one side of the head, are pulsating in nature, and last for 2 to 72 hours [32]. The symptoms can be nausea, vomiting, and sensitivity to light, sound, or smell [33]. The pain is generally made worse by physical activity [34]. Up to one-third of people have an aura: typically a short period of visual disturbance which announces the onset of headache in advance [34]. Occasionally, an aura can occur with little or no headache after that [35]. Migraines are believed to be due to a mixture of environmental and genetic factors [36].
Multiple sclerosis (MS): a disease affecting or damaging the myelin which is the covering layer of nerve cells in the brain or spinal cord [37]. This damage disrupts communication between cells in the nervous system resulting in many signs and symptoms, including physical, mental, and sometimes psychiatric problems [38–40]. Double-vision, blindness of one eye, muscle weakness, trouble with sensation, and trouble with coordination are the specific symptoms [37]. MS is a degenerative disease and gradually goes to complexity. Brain MS is more severe. Although the actual cause is not clear, the underlying mechanism is thought to be either destruction of the immune system or failure of the myelin-producing cells.
Paralysis: the inability to move a part of the body temporarily or permanently. In almost all cases, paralysis is due to nerve damage, not to an injury to the affected region. Often an injury in the middle or lower regions of the spinal cord is likely to disrupt function below the injury, including the ability to move the feet or feel sensations, even though the actual structures are completely healthy. In this situation, the brain is unable to relay a signal to an area of the body due to injuries to the brain. However, in some cases the brain is able to sense touch and other sensations in the body, but is unable to effectively relay a response due to injuries in the spinal cord.
Parkinson's: a degenerative brain disorder. The cause is generally unknown but believed to be genetic or due to environmental factors [41]. Physiologically, the dopamine generators of the brain fail in generating sufficient dopamine as the result of death of cells in the substantia nigra in the midbrain region [42]. Diagnosis of typical cases is mainly based on symptoms such as tremor, rigidity, slowness of movement, difficulty in walking, dementia, depression, and anxiety.
Pick's disease: a rare form of dementia and similar to Alzheimer's, except that it often affects only certain brain zones. It has unknown causes and people with Pick's disease have abnormal substances (called Pick bodies and Pick cells) inside nerve cells in the damaged areas of the brain.
Seizure and epileptic seizure;: a temporary loss of control often, but not always, accompanied by convulsions, unconsciousness, or both. Most common types are epileptic seizures, or seizures, are caused by sudden abnormal electrical discharges in the brain. An epileptic seizure, also known as an epileptic fit, seizure, or fit, manifests itself in the form of a brief episode of signs or symptoms due to abnormal excessive or synchronous neuronal activity in the brain [43]. The outward effect can vary from uncontrolled jerking movement (tonic–clonic seizure) to something as subtle as a momentary loss of awareness (absence seizure). Diseases of the brain characterised by an enduring predisposition to generate epileptic seizures are collectively called epilepsy [44]. On the other hand, for nonepileptic seizures the brain activity remains normal. Nonepileptic seizures have no identifiable physical cause, but they are believed to be physical reactions to psychological stress, change of emotions, in some cases due to tumour in the brain, or as symptoms of hypertension.
Brain tumour: a growth of cells in the brain that multiplies in an abnormal, uncontrollable way. Brain tumours can be malignant, slow growing, or benign. The most common brain tumour is a glioma, which has different types including astrocytomas, glioblastomas, oligodendrogliomas, mixed gliomas, and ependymomas. Some grow slowly while others grow more quickly.
Meningioma: a common brain tumour. It starts in the meninges, the tissue covering the brain and spinal cord, and is usually benign. A lymphoma is a cancer of the lymphatic system. It rarely starts in the brain. An acoustic neuroma is a benign tumour of the hearing nerve. Another benign brain tumour that starts in cells lining blood vessels is a haemangioblastomas.
Tumours that start in the pituitary gland, which helps control hormones, are also benign. There are also tumours which start in the spinal cord and they are usually benign. Tumours of the pineal gland, such as germinomas and teratomas, are rare. They can be slow or fast growing. Medulloblastoma tumours are rare in adults but more common in children.
In the next chapters of this book we will see how single or multiple sensor systems can record and detect the clinically important features related to most of the above abnormalities.
Human development, often referred to as developmental psychology, explains the changes in human cognitive, emotional, and behavioural capabilities and functioning over the entire life.
On the other hand, the availability of monoclonal antibodies, routine production of genetically altered animals, and new understanding of the genetic code have contributed to the exploration of how genetics interacts with development and early experiences to influence both vulnerability to disease and resistance to age-related decline.
The combination of biology and society makes us what we are and what we do. The three main elements of biology contributing to human behaviour are: (i) self-preservation; (ii) the reason for self-preservation, reproduction; and (iii) a method to enhance self-preservation and reproduction [45].
As another important biological effect, biological rhythms are related to the changes in mood and consequently the human behaviour. These rhythms control much of the body's normal functions, including performance, sleep, and endocrine rhythms as well as behaviour. These functions are primarily regulated by the circadian clock, a cluster of nerves located in the hypothalamus in the brain. The circadian clock relies on environmental cues to regulate its function, primarily light cues from the day/night cycle. Any shift in these cues, such as by travel resulting in jet lag, can alter the sleep cycle and have a detrimental effect on normal circadian rhythms. In addition, season changes, which are accompanied by a decrease in the number of daylight hours, can negatively impact the function of the circadian clock, primarily the secretion of melatonin to induce sleep. If the alterations in biological rhythms are sufficiently strong, they may lead to mood disorders including mild depression and seasonal affective disorder [46].
There are two major categories of biological rhythms: endogenous and exogenous. Endogenous rhythms come from within the organism and are regulated by the organism itself, for example the body temperature cycle, brain rhythms, or heart rate. Exogenous rhythms are the result of external factors, such as a change in the seasons or transition from day to night. The environmental stimuli referred also to as zeitgebers, from the German for ‘time givers’, help
