Chapter 5 Flashcards
anosognosia
Lack of awareness of one’s own disability.
Apraxia
a loss of the ability to execute learned voluntary movements, especially
complex sequences of movements, despite the motivation and physical capability to perform the actions
Ideational apraxia
the inability to carry out sequential tasks involving the use of tools or objects in the proper order
verbal apraxia
Results in difficulty
producing speech. Verbal apraxia can afflict both adults and children, the latter
having potentially devastating consequences for learning and socialization.
basal ganglia
A group of nuclei lying deep in the subcortical white matter of the frontal lobes that organize motor behavior. The caudate, putamen, and globus pallidus are major components of the basal ganglia; the subthalamic nucleus and substantia nigra are often included.
cerebellum
The prominent hindbrain structure that is concerned with motor coordination, posture, balance, and some cognitive processes; composed of a three-layered cortex and deep nuclei, and attached to the brainstem by the cerebellar peduncles.
choreiform movement
Uncontrollable, dancelike (“choreiform”) writhing or twisting associated with damage to the basal ganglia, as occurs in disorders such as Huntington’s disease.
frontal eye fields
A region of the prefrontal cortex in human and non-human primates, often associated with area 8a, that plays a key role in voluntary visual orienting movements.
gating
Allowing or permitting. The basal ganglia, for example, gate movement initiation. Channels through the neuronal membrane are often gated, allowing the access of certain ions under certain conditions.
hemiballismus
A neurological disorder resulting from unilateral damage to the basal ganglia; manifested by flinging movements of the limbs contralateral to the lesion.
Huntington’s disease
An autosomal dominant genetic disorder in which a single gene mutation results in damage to the basal ganglia that causes personality changes, progressive loss of the control of voluntary movement, and eventually death.
intention tremor
A tremor that occurs during performance of a voluntary motor act. Characteristic of cerebellar pathology.
local circuit neuron
Also called interneuron. A neuron whose local connections contribute to processing circuitry
lower motor neuron
Also called primary motor neuron. A motor neuron that directly innervates muscle.
medullary pyramids
Longitudinal bulges on the ventral aspect of the medulla that signify the corticospinal tracts at this level of the nervous system.
motor program
The plan to produce a particular motor action, such as writing one’s name, that occurs independently of the effectors used to carry out the movement.
optic ataxia
A neurological condition associated with damage to the dorsal parietal cortex and characterized by deficits in visually guided reaching.
Parkinson’s disease
A neurodegenerative process affecting the substantia nigra that results in a characteristic tremor at rest and a general paucity of movement.
premotor cortex
Part of the prefrontal cortex lying just anterior to the primary motor cortex; involved in planning movement.
premotor cortical areas
Cortical areas, including the premotor cortex, supplementary motor cortex, and parts of the parietal cortex, that provide motor programming signals to the primary motor cortex.
primary motor cortex
A major source of descending projections to motor neurons in the spinal cord and cranial nerve nuclei; located in the precentral gyrus (area 4) and essential for the voluntary control of movement.
readiness potential
An electrical potential, recorded from the motor and premotor cortices with EEG electrodes, that signals the intention to initiate a voluntary movement well in advance of actual production of the movement.
reward value
The likelihood that a particular movement will yield a reward, multiplied by the amount of reward expected.
saccade
A ballistic eye movement that changes the point of binocular visual fixation; normally occur at a rate of about three to four per second.
striatum
The input nuclei of the basal ganglia, consisting of the caudate and the putamen. So called because of the striped appearance of these structures in brain sections.
substantia nigra pars reticulata (SNr)
A component of the midbrain substantia nigra nucleus that plays a key role in the suppression and initiation of saccadic eye movements.
superior colliculi (sing. superior colliculus)
Paired structures that form part of the roof of the midbrain; important in orienting movements of the head and eyes.
supplementary motor cortex
Also called supplementary motor area or area 6. A premotor area, lying anterior to the primary motor cortex on the medial surface of the cerebral hemisphere, that plays an important role in movement planning.
upper motor neuron
A neuron that gives rise to a descending projection that controls the activity of lower motor neurons in the brainstem and spinal cord.
