The Neuroscience on the Web Series:
Glossary of Neuroscience Terms M-P


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M

 

magnum foramen:
the large opening in the base of the skull
 
mamillary bodies (mamillary nucleus):
subcortical component of the limbic system (rhinencephalon); the mamillary bodies are connected to the hippocampus, the thalamus, and the fornix
 
masked facies:
Parkinson's patients usually display little facial expression, so their faces are described as "mask-like."
 
massa intermedia (thalamic adhesion):
the tissue that connects the two thalamic bodies
 
masseter muscle of the oral cavity:
elevates and closes the mandible
 
MTDDA: Minnesota Test for Differential Diagnosis
 
medial:
toward the center
 
medial muscle of the oral cavity:
which also elevates the mandible and aids in its closure
 
medial aspect:
the part of the motor strip that extends down into the longitudinal cerebral fissure; it controls the movements of the body from the hips downward
 
medial cut:
a section that divides the brain into right and left halves of equal size; it separates the hemispheres from each other; a medial cut is a type of sagittal cut
 
medial geniculate bodies:
the thalamic nuclei that receive auditory information from the inferior colliculi of the midbrain, process, and then transmit this information to the cortex
 
medulla oblongata:
the most inferior structure of the brain stem; the "bulb"; the medulla is involved in circulation and respiration
 
Melodic Intonation Therapy:
(Sparks & Holland, in Chapey, 1994)  Melodic intonation therapy, or MIT, uses music to involve the non-dominant hemisphere in language production. originally developed by Sparks and Holland for the treatment of severe non-fluent aphasia. Currently, however, it is frequently used to treat individuals with apraxia. This technique involves teaching the patient to sing words or phrases set to simple melodies. It is hypothesized that this therapy is effective because the use of music helps involve the right hemisphere in the production of speech.
 
Mendelsohn Maneuver:
helps the patient gain some voluntary control over the opening and closing of the p.e. segment. The patient is told to pay attention to the way the thyroid cartilage goes up and down during swallowing. Then he learns to use muscles to keep the larynx elevated for several seconds after the swallow. This should facilitate the opening of the cricopharyngus muscle.
 
meninges:
dura mater, arachnoid and pia mater, three layers of protective tissue that surround the neuraxis; the meninges of the brain and spinal cord are continuous and are connected through the magnum foramen
 
micrographia:
often seen with parietal lobe lesion, the "tendency for handwriting to be very small in the height of the letters and to get progressively smaller as the person continues to write" (Love and Webb, 1992, p. 146).
 
midbrain (mesencephalon):
the most superior part of the brain stem
 
middle cerebellar peduncle (middle brachium pontis):
the largest of the cerebellar peduncles; the middle cerebellar peduncle connects the cerebellum with the pons; through this connection the cerebellum receives a copy of the information for muscle movement that the pyramidal tract carries to lower motor neurons
 
middle cerebral artery:
a branch of the internal carotids; the middle cerebral artery supplies blood to the entire lateral aspect of each hemisphere (including the lateral motor strip, lateral sensory strip, Broca's area, Wernicke's area, Heschl's gyrus, angular gyrus) and to the corpus striatum
 
middle meningeal artery:
this artery sometimes ruptures after traumatic brain injury
 
Minnesota Test for Differential Diagnosis: (MTDDA)
developed by Schuell in 1965. This comprehensive test assesses the patient's strengths and weakness in all language modalities.
 
Mixed dysarthria:
occurs when both upper and lower motor neurons are injured, amyotrophic lateral sclerosis (Lou Gehrig's Disease) is the most frequent cause of mixed dysarthrias. Etiology is unknown and prognosis is poor.
 
Mixed Nonfluent Aphasia:
diagnosis given to patients who produce language that is similar to the telegraphic speech characteristic of Broca's aphasia, but cannot be categorized as actually having Broca's aphasia due to the severity of their auditory comprehension deficits.
 
modified barium swallow:
procedure used to image the swallowing process is a modified barium swallow, not a true barium swallow. the patient consumes foods of varying consistencies that have been coated with barium.A true barium swallow is used to view the esophagus
 
molecular commotion:
(Love and Webb, 1992) a disruption in the molecular structure of the brain which may cause permanent changes in both white and grey matter
 
molecular layer:
the most superior layer of the cortex; it contains the cell bodies of neuroglial cells
 
muscularis uvula (oral cavity):
shortens the velum. It is also innervated by the spinal accessory (CN XI).
 
Myasthenia Gravis:
According to Fitz Gerald (1996), it is caused by the immune system producing antibodies to the ACh receptor. This disease impairs the ability of nerve fibers to synapse with the muscles by reducing the number of acetylcholine (ACh) receptors at the neuromuscular junction. It causes weakness in muscles throughout the body, especially those involved in speech and swallowing. This weakness is progressive. In the morning or after rest, the patient's speech may sound clear. However, as he becomes fatigued, slurring of speech will increase.
 
myelin:
a fatty insulating substance that covers, at regular intervals, many of the axons in the central and peripheral nervous system; myelin serves to increase the speed of transmission of impulses, by allowing them to jump from one unmyelinated segment to the next (this is called saltatory conduction)
 
myotomy:
the procedure of cutting the cricopharygeus muscle

N

 

neuraxis:
the brain and spinal cord; the central nervous system
 
Neuronal Unmasking:
(Bach-y-Rita, 1989) Neurons which are normally quiescent may begin working again after others have been destroyed. This means that brain processes which are normally inhibited by higher level controls will be able to function. This may help in recovery. Negative effects of unmasking are reflexes and responses like the startle reflex which are usually only seen in young children. The Babinski reflex and the patilla reflex may also be abnormal after head injury.
 
neurons:
the nerve cells of the central and peripheral nervous systems; a neuron is composed of an axon, a soma, and dendrites (while all neurons have one soma and one axon, some neurons have many dendrites and others have none)
 
neurological input for the swallow
in the initiation in the swallow comes from the trigeminal, facial, and glossopharyngeal nerves
 
neocerebellum:
the posterior lobe of the cerebellum; it is considered to be the newest part of the cerebellum; it is involved in the coordination of muscle movement through the inhibition of involuntary movement, it is also involved in fine motor coordination
 
neologistic paraphasias:
less than half of the intended word is produced correctly. In some cases the entire word is produced incorrectly. Neologisms are also common in the speech of schizophrenics.
 
NG tubes and swallowing:
naso-gastric feeding tube; According to Logemann (1989), its not necessary to wait until tubes are removed to begin therapy.
 
Nodes of Ranvier:
the segments of axons between areas of myelin, which are in direct contact with extracellular fluid
 
nodulus:
the narrowest and most inferior part of the vermis; it is part of the flocculonodular lobe of the cerebellum
 
nonfluent aphasias:
Nonfluent aphasias are the result of damage to the area of the brain anterior to the central sulcus (Broca's area)
 
The flow of speech is more or less impaired at the levels of speech initiation, the finding and sequencing of articulatory movements, and the production of grammatical sequences. Speech is choppy, interrupted, and awkwardly articulated.
 
Comprehension appears to be better than production and in a sense it is. The linguistic competence underlying both comprehension and production of language is the same, so both comprehension and production are affected by a nonfluent aphasia. However, just as it is easier to understand a second language than to produce it, it is easier for the patient to understand what is said than to speak. One can often get by with only comprehending the key words and using non-verbal cues.

O

 

obicularis oris:
lip muscle, with the buccinator and zygomaticus  innervated by the facial nerve (CN. VII).
 
occipital lobe:
the most posterior lobe of the brain; it is associated with vision
 
olfactory pathways:
the olfactory pathways originate in the nasal area and pass posteriorly to enter the temporal lobe at the hippocampal gyrus; the olfactory tract is immediately superior to the optic tract
 
olivary nuclei:
landmarks in the medulla which lie posterior to the pyramids; the olivary nuclei are involved in the processing and relaying of auditory information
 
operant conditioning:
a form of behavior modification, used to remediate aphasia. This approach involves shaping language behavior by helping patients to progress through a series of tasks presented in fixed order, from least to most difficult.
 
oral apraxia:
an inability to make voluntary, non-speech oral movements
 
oral preparatory phase of the swallow:
voluntary,  mechanical phase that can be by-passed by dropping liquid or food into the back of the throat.In this stage, the food is chewed into smaller pieces and tasted. It is also mixed with saliva from three pairs of salivary glands, which are innervated by the glossopharyngeal nerve. The food and saliva form a bolus of material. The bolus is kept in the front of the mouth, against the hard palate by the tongue. The front of the tongue is elevated with its tip on the alveolar ridge. The back of the tongue is elevated and the soft palate is pulled anteriorly against it  (the airway is open and nasal breathing continues during this phase). Labial seal is maintained to prevent food from leaking out of the mouth. Buccal muscles are tense.  Duration of the oral-preparatory stage is variable (Logemann, 1983, 1997).
 
oral transport stage of the swallow:
voluntary stage, starts with the jaws and lips closed, and the tongue tip on the alvealor ridge. The pattern-elicited response is initiated at the end of this phase. Inspiration is reflexively inhibited at the beginning of this stage. The food is moved to the back of the mouth by the tongue via an anterior to posterior rolling motion. The anterior portion of the tongue is retracted and depressed while the posterior portion is retracted and elevated against the hard palate. When the bolus passes the anterior faucial pillars/touches the posterior wall of the pharynx, the oral stage ends and the pharyngeal stage begins as the tongue driving force or the tongue's plunger action, forces the bolus into the pharynx. Logemann (1997) describes the "pharyngeal tongue" which extends from the velum to the hyoid bone and valleculae. The "oral tongue" which extends from the tip to the back, adjacent to the velum, functions during the oral stage of the swallow while the "pharyngeal tongue" functions during the pharyngeal stage. This stage lasts one second (Logemann, 1989, 1998; Dobie, 1978).  

P

 

pacing board
may be helpful for patients with dysarthria, divided into sections, the patient must tap one section every time he pronounces a syllable. As the fingers cannot move nearly as rapidly as the articulators, this should slow the rate of speech enough to improve intelligibility. After reduced rate has been established using the board, the client can begin to count syllables on his fingers. Eventually, he should be able to maintain the proper rate without counting syllables at all. A device called a graduated stick may be used instead of a pacing board. Graduated sticks have bumps on them at regular intervals and the patient  must touch one bump every time he says a syllable. Metronomes can also be used to slow speech rate. Patients are taught to produce one syllable per "tick" on the metronome.
 
palatoglossal muscle (oral cavity):
with the levator veli palatini both raise the velum. They are innervated by the vagus nerve (CN. X)
 
palatopharyngus muscle (oral cavity):
depresses the velum and constricts the pharynx. It is innervated by the spinal accessory (CN. XI).
 
paleocerebellum:
the anterior lobe and second oldest part of the cerebellum; the paleocerebellum receives proprioceptive input from the spinal cord and controls the anti-gravity muscles of the body, it thus regulates posture
 
Pallilalia:
the compulsive repetition of syllables sometimes present in hypokinetic dysarthria
 
paraphasia:
the production of unintended syllables, words, or phrases during the effort to speak" (Goodglass & Kaplan, 1983, p. 8). Patients with fluent forms of aphasia exhibit many more paraphasias than do those with nonfluent types. There are three types of paraphasias, literal/phonological, neologistic, and semantic/verbal.
 
parasympathetic nervous system:
a division of the autonomic nervous system; it helps to bring the body back to normal
 
parenchyma
means "specific cells of a gland or organ" (Stedman's Concise Medical Dictionary, 1997). Parenchymal bleeding refers to the flow of blood into brain tissue rather than into an existing space like the subarachnoid space or a potential space like the subdural space. Parenchymal hemorrhages occur most frequently in the putamen, thalamus, pons, and cerebellum (Coch & Metter, 1994).
 
paragrammatical:
(Goodglass and Kaplan, 1983) patients with Wernicke's Aphasia make grammatical errors but their speech cannot be considered agrammatical as it does contain complex syntactical forms
 
parietal lobe:
the lobe of the brain which is immediately posterior to the central sulcus, anterior to the occipital lobe, and superior to the posterior portion of the lateral fissure (and thus the temporal lobe); it is associated with sensation (touch, kinesthesia, perception of temperature, vibration), writing, and some aspects of reading
 
Parkinson's Disease:
a degenerative disease, is probably the most frequently occurring illness that results from extrapyramidal tract lesions. It occurs when the dopaminergic neurons of the substantia nigra are destroyed. Its symptoms include:

Tremor, Festinating movements( these movements can also affect speech), Hypokinetic dysarthria, weak voice, and mask-like facial expression. Recent research indicates that those who acquire the disease prior to age 50 may have genetic causation.
 
pattern-elicited response:
the swallow was previously classified as a reflex, most sources now disagree and label it pattern-elicited
 
perilymph:
fluid of the inner ear; it surrounds the utricle, saccule, and semicircular canal
 
peripheral lesions:
lesions to the axons of the cranial nerves; these are considered to be lesions of the final common pathway
 
peripheral nervous system:
the cranial nerves and spinal nerves
 
peristalsis:
wave-like motions of muscles that occur in the esophagus. In some of the literature, the action of the pharyngeal constrictor muscles is mistakenly called peristalsis, rather than a stripping action.
 
pharyngeal-esophageal (P.E) segment or cricopharyngus m.:
separates the pharynx from the esophagus. At the end of the pharyngeal stage of the swallow, it must relax to allow the bolus to enter the esophagus. (It is normally closed to prevent the reflux of food and to keep air out of the digestive system.)
 
pharyngeal recesses:
the valleculae is a space or depression between the base of the tongue and the epiglottis, two pyriform sinuses are located in the pharynx, beside the larynx. They are formed by the shape of muscle attachments to the pharyngeal walls.  Food boluses can lodge in these recesses.
pharyngeal stage of the swallow: (Logemann, 1989, 1997, 1998; Cherney, 1994)

involuntary, and most critical stage of the swallow; airway closure must occur to prevent the bolus from entering the respiratory system. Almost simultaneously: 1.Sensory information from receptors in the back of the mouth and in the pharynx goes to the swallowing center in the medulla via CN. IX. The palatopharyngeal folds pull together medially to form a slit in the upper pharynx. The bolus passes through this slit. 2. The velum is raised, primarily by the levator and tensor veli palatini muscles. 3. The tongue is retracted
 
Has a laryngeal substage in which three actions occur simultaneously  (Obviously, inspiration is inhibited during the pharyngeal stage of the swallow.) 1.The larynx and the hyoid bone are pulled both upward and forward.  2.The true and false vocal folds adduct. (Closure begins at the level of the true vocal folds and progresses up to the false vocal folds and then to the ari-epiglottic folds.) 3.The epiglottis drops down over the top of the larynx,   The bolus passes down on both sides of the epiglottis. If the bolus is liquid, the epiglottis acts as a ledge to slow its movement through the pharynx, giving the vocal folds time to adduct and the larynx time to elevate.

Three factors cause food to move down the pharynx during the rest of the pharyngeal stage (Cherney, et al., 1994; Logemann, 1983, 1989, 1997): The tongue driving force using the "pharyngeal tongue", the stripping action of the pharyngeal constrictors and   the presence of negative pressure in the laryngopharynx

The pharyngeal stage ends when the cricopharyngus muscle relaxes.
 
pia mater:
the innermost layer of the meninges; it adheres closely to the brain, descending into the sulci and fissures of the cortex and fuses with the ependyma to form the choroid plexes
Pill-rolling tremor:
Parkinson's  patients move their thumbs and forefingers together as if rolling a small pill between them. This movement occurs at rest, but subsides during voluntary movement and sleep.
 
pituitary gland:
an endocrine gland of the central nervous system; secretes a number of different hormones
 
plaque:
composed of cholesterol build up and smooth muscle cells
 
plunger action or or the tongue driving force:
plays a major role in this process.in the movement of food down the pharynx, according to the  latest research on swallowing disputes the action of the pharyngeal constrictor muscles as the most critical factor
 
pneumoencephalography:
a technique used prior to the introduction of CT, MRI, and PET technology, in which a small amount of cerebrospinal fluid is removed from the ventricles and replaced with an inert gas, allowing the examiner to view the ventricles in a scan and assess brain pathology
 
polycythemia:
a thickening of the blood due to an increase in the number of cells.
 
pons:
the brain stem structure located between the midbrain and medulla; fibers in it connect the brain stem to the cerebellum; pons is Latin for "bridge"
 
Porch Index of Communicative Ability: (PICA)
(Porch, 1967) samples fewer language behaviors than the MTDDA. However, it is known for its elaborate scoring system, which allows the examiner to differentiate between responses elicited with different degrees of cueing, various types of errors, and also to note the immediacy of the response.
 
postcentral gyrus (primary sensory area, sensory strip):
the area of the brain located in the parietal lobe immediately posterior to the central sulcus; this area receives sensory feedback from the muscles, joints and tendons in the body; the postcentral gyri have lateral and medial aspects
 
posterior:
toward the back (opposed to anterior)
 
posterior cerebral arteries:
arteries that arise from the basilar artery (before it divides); the posterior cerebral arteries supply blood to the posterior areas of the brain, including the medial parts of the occipital lobes, and the inferior areas of the temporal lobes, as well as supplying blood to the thalamus and other subcortical structures
 
posterior commissure:
one of the three major groups of commissural fibers
 
posterior communicating arteries:
arteries that arise from the internal carotid arteries; they join the middle cerebral arteries to the posterior cerebral arteries
posterior lesions:
problems with meaning are associated with posterior lesions
 
post-ganglionic cells:
neurons of the autonomic nervous system that are located in its target organs and muscles
 
post Rolandic area:
lesions in this area result in fluent aphasia, these are posterior lesions and result in problems with meaning
 
precentral gyrus (primary motor area, motor strip):
a gyrus in the frontal lobe which controls the voluntary movements of skeletal muscles; it is located immediately anterior to the central sulcus and has a lateral and medial aspect; the cell bodies of the pyramidal tract are found here
 
pre-ganglionic cells:
neurons of the autonomic nervous system that are located in some of the cranial nerves of the brain stem and in some spinal nerves; they project to the ganglionic chains of the autonomic nervous system
 
premotor areas (supplemental motor areas):
Brodmann's Area 6, areas located immediately anterior to the motor strip; this portion of the frontal lobe is responsible for the programming of motor movements (except speech)
 
presensory areas (secondary sensory areas or sensory association areas):
areas located posterior to the postcentral gyrus; these areas are capable of more detailed discrimination and analysis than the primary sensory areas
 
press of speech:
phenomenon characterizes Wernicke's aphasics. Patients may speak very rapidly, interrupting others. It may seem as though the patient is striving for a sense of closure or a sense that he has actually communicated what he intended to say (Goodglass and Kaplan, 1983).
 
primary auditory cortex:
Brodmann's areas 41 and 42
 
primary visual area:
an area located within the occipital lobe; it receives input from the optic tract; damage to this area may cause blind spots in the visual field or total blindness
 
pragmatic approaches:
use social interaction to improve the communicating abilities of aphasic patients.
 
programmed stimulation:
LaPointe (1990), approach to aphasia therapy combines behavioral and cognitive methods. He advocated the use of a hierarchy of therapy tasks based on level of difficulty employed by behaviorists, but uses the kinds of stimuli employed by therapists with a cognitive orientation. Several types of programmed stimulation for aphasics have been developed by other therapists. Among these are melodic intonation therapy (Sparks & Holland, in Chapey, 1994) and visual action therapy VAT (Fitzpatrick & Baresi, 1982).
 
progressive strokes:
still evolving, meaning that the patient's condition is continuing to deteriorate. Progressive strokes can last for over a week. This condition is usually the result of a severe hemorrhage.Particular caution should be used when evaluating the swallowing status of such a patient. Also, progressive strokes tend to happen to people who have very poor cerebral vascular health and are therefore at risk for having another stroke very soon.
 
promoting aphasic's communicative effectiveness (PACE):
developed by G. Albyn Davis,  based on the pragmatic rule of reciprocity; the therapist and the patient participate in a conversation as equals, each taking turns sending and receiving messages. According to Davis and Wilcox (1981)PACE is based on the following four principles, The Exchange of New Information, Free Choice of Communicative Channels, Equal Participation, Functional Feedback
 
proprioception:
sensory information about pressure, movement, vibration, position, muscle pain, and equilibrium that is received by the brain (especially the cerebellum) from the muscles, joints, and tendons
 
prosopagnosia:
inability to recognize faces
 
pseudobulbar palsy:
the paralysis that results from bilateral upper motor neuron lesions of the pyramidal tract; it produces a paralysis very similar to that seen with bulbar palsy
 
putamen:
the more lateral part of the lenticular nucleus
 
Purkinje cells:
radish-shaped cells located in the cerebellar cortex that regulate and inhibit the firing of the deep nuclei, thus controlling the output of the cerebellum
 
pyramidal tract:
a fiber tract that carries messages for voluntary motor movement to the lower motor neurons in the brain stem and spinal cord; the pyramidal tract is direct and monosynaptic, pyramidal tract, which is the most important of the upper motor neuron tracts, transmits messages directing voluntary motor movements. It is primarily facilitory  (Duffy, 1995).  
 
pyramids:
landmarks in the medulla which mark the decussation of the pyramidal tract; they lie on either side of the medial fissure