Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

Principles of Neural Science

The approach taken in this study to produce localised changes of cerebral excitability in the intact human was modulation of neuronal excitability by weak electric currents applied transcranially. So far, this technique has mainly been used in animal research, primarily through modulation of the resting membrane potential (Terzuolo & Bullock, 1956; Creutzfeld et al. 1962; Eccles et al. 1962; Bindman et al. 1964; Purpura & McMurtry, 1965; Artola et al. 1990; Malenka & Nicoll, 1999). In general, cerebral excitability was diminished by cathodal stimulation, which hyperpolarises neurones. Anodal stimulation caused neuronal depolarisation, leading to an increase in excitability (Bindman et al. 1962; Purpura & McMurtry, 1965), as was shown by spontaneous neuronal discharges and the amplitudes of evoked potentials (Landau et al. 1964; Purpura & McMurtry, 1965; Gorman, 1966). However, in single cortical layers opposite effects were seen (Purpura & McMurtry, 1965), underlining the fact that the effects of DC stimulation depend on the interaction of electric flow direction and neuronal geometry. Enduring effects of 5 h and longer have been described if the stimulation itself lasts sufficiently long, about 10–30 min. These prolonged effects are not simply due to prolonged membrane potential shifts or recurrent excitation, because intermittent complete cancellation of electrical brain activity by hypothermia does not abolish them (Gartside, 1968a,b). Long-term potentiation (LTP) and long-term depression (LTD) have been proposed as the likely candidates for this phenomenon (Hattori et al. 1990; Moriwaki, 1991; Islam et al. 1995; Malenka & Nicoll, 1999).

The concept described here was an attempt to induce neuronal excitability changes in man by application of weak DC stimulation through the intact skull. It has already been demonstrated within invasive presurgical epilepsy diagnostics that intracranial currents of sufficient strength can be achieved in humans by stimulation with surface electrodes at intensities of up to 1.5 mA (Dymond et al. 1975). A suitable candidate for evaluating cortical excitability changes is transcranial magnetic stimulation (TMS), because it allows the quantification of motor-cortical neurone responses in a painless and non-invasive manner. The amplitude of the resulting motor-evoked potential (MEP) represents the excitability of the motor system. In the following, we confirm the principal possibility of altering cortical excitability by applying weak DC. Furthermore we show that systematic DC stimulation with minimum stimulation duration and intensity is necessary for an effective application of weak current in humans. This is of particular importance for inducing effects which outlast the duration of stimulation.

https://physoc.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7793.2000.t01-1-00633.x

Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation.

https://bic.berkeley.edu/sites/default/files/Rossi_09_TMS%20safety%20review.pdf

Safety, ethical considerations, and application guidelines for the use of transcranial magnetic stimulation in clinical practice and research

https://deepblue.lib.umich.edu/bitstream/handle/2027.42/90300/j.ejpain.2004.11.001.pdf?sequence=1

Human brain mechanisms of pain perception and regulation in health and disease.

The social and psychological impact of dysphagia has not been routinely reported in large studies. We sought to determine the effects of dysphagia on broad measures of the quality of life of patients and to explore the relationship between the psychological handicaps of the condition and the frequency of diagnosis and treatment. A total of 360 patients selected on the basis of known subjective dysphagia complaints, regardless of origin, in nursing homes and clinics in Germany, France, Spain, and the United Kingdom were interviewed using an established questionnaire. Qualitative interviews with a total of 28 health professionals were conducted to improve understanding of the patient data in the context of each country. Over 50% of patients claimed that they were "eating less" with 44% reporting weight loss during the preceding 12 months. Thirty-six percent of patients acknowledged receiving a confirmed diagnosis of dysphagia; only 32% acknowledged receiving professional treatment for it. Most people with dysphagia believe their condition to be untreatable; only 39% of the sufferers believed that their swallowing difficulties could be treated. Eighty-four percent of patients felt that eating should be an enjoyable experience but only 45% actually found it so. Moreover, 41% of patients stated that they experienced anxiety or panic during mealtimes. Over one-third (36%) of patients reported that they avoided eating with others because of their dysphagia. In a largely elderly population that might accept dysphagia as an untreatable part of the aging process, clinicians need to be aware of the adverse effects of dysphagia on self-esteem, socialization, and enjoyment of life. Careful questioning should assess the impact of the condition on each patient's life, and patients should be educated on their choices for treatment in the context of any coexisting illness. Awareness of the condition, diagnostic procedures, and treatment options must be increased in society and among the medical profession.

Social and psychological burden of dysphagia: its impact on diagnosis and treatment.

Removal of sensory input can induce changes in cortical motor representation that reverse when sensation is restored. Here we ask whether manipulation of sensory input can induce long-term reorganization in human motor cortex that outlasts the initial conditioning. We report that for at least 30 minutes after pharyngeal stimulation, motor cortex excitability and area of representation for the pharynx increased, while esophagus representation decreased, without parallel changes in the excitability of brainstem-mediated reflexes. Therefore increased sensory input can drive long-term cross-system changes in motor areas of the cerebral cortex, which suggests that sensory stimulation might rehabilitate dysphagia, a frequent consequence of cerebral injury.

Long-term reorganization of human motor cortex driven by short-term sensory stimulation.

Because no detailed information exists regarding the topographic representation of swallowing musculature on the human cerebral cortex in health or disease, we used transcranial magnetic stimulation to study the cortical topography of human oral, pharyngeal and esophageal musculature in 20 healthy individuals and the topography of pharyngeal musculature in two stroke patients, one with and one without dysphagia. Our results demonstrate that swallowing musculature is discretely and somatotopically represented on the motor and premotor cortex of both hemispheres but displays interhemispheric asymmetry, independent of handedness. Following stroke, dysphagia appeared to be associated with smaller pharyngeal representation on the intact hemisphere, which increases in size with recovery of swallowing.

The cortical topography of human swallowing musculature in health and disease

Driving plasticity in human adult motor cortex is associated with improved motor function after brain injury.

Functional magnetic resonance imaging (fMRI) provides a safe, noninvasive method for studying task-related cortical neuronal activity. Because the cerebral cortex is strongly implicated in the cont...

Shaheen Hamdy

Papers

Social and psychological burden of dysphagia: its impact on diagnosis and treatment.

Long-term reorganization of human motor cortex driven by short-term sensory stimulation.

The cortical topography of human swallowing musculature in health and disease

Driving plasticity in human adult motor cortex is associated with improved motor function after brain injury.

Cortical activation during human volitional swallowing: an event-related fMRI study.