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Terms in this set (33)
a brainstem nucleus that is part of the basal ganglia. primary source of neurotransmitter dopamine.
part of the body that can move.
alpha motor neurons
originate in the spinal cord, exit through the ventral root, and terminate in the muscle fibers. provide a physical basis for translating nerve signals into mechanical actions.
primary source of control over spinal activity. receive input from subcortical and cortical structures.
massive structure tat receives extensive sensory inputs, including information from somatosensory, vestibular, visual, and auditory channels.
collection of 5 subcortical nuclei: the caudate, putamen, globes pallid us, sub thalamic nucleus, and substantia nigra. involved in motor control and learning.
composed of neurons that originate in the cortex and terminate directly on alpha motor neurons or spinal interneurons.
primary motor cortex (M1)
region of the cerebral cortex that lies along the anterior bank of the central suclus and precentral gyrus, forming Brodmann area 4. some axons originating in the primary motor cortex form the majority of the corticospinal tract; others project to cortical and subcortical regions involved in motor control. the primary motor cortex contains prominent somatotopic representation of the body.
a secondary motor area that includes the lateral aspect of Brodmann area 6, just anterior to the primary motor cortex. although some neurons in the premotor cortex project to the corticospinal tract, many terminate on neurons in the primary motor cortex and help shape the forthcoming movement.
supplementary motor area
a secondary motor area that includes the medial aspect of Brodmann area 6, just anterior to the primary motor cortex. the SMA plays an important role in the production of sequential movements, especially those that have been well learned.
a hypothesis concerning how movements are planned in terms of the desired final location. endpoint control models emphasize that the motor representation is based on the final position required of the limbs to achieve the movement goal.
a statistical procedure to represent the activity across a group of neurons. population vectors reflect the aggregate activity across the cells, providing a better correlation with behavior than that obtained from the analysis of individual neurons.
a device that uses the interpretation of neuronal signals to perform desired operations with a mechanical device outside the body.
a neurological syndrome characterized by loss of skilled or purposeful movement that cannot be attributed to weakness or an inability to innervate the muscles. Apraxia results from lesions of the cerebral cortex, usually in the left hemisphere.
form of apraxia in which the patient's knowledge about the intent of an action is impaired. does not know the use of a tool but is still capable of identifying the tools required movement.
form of apraxia in which the patient has difficulty executing the desired action properly. patients appear to have a general idea about how the action should be performed and how tools are used, but are unable to coordinate movements to produce the action.
a degenerative disorder of the basal ganglia in which the pathology results from the loss of dopaminergic cells in the substantia nigra. symptoms include difficulty in initiating movement, slowness of movement, poor speech.
slowness in the initiation and execution of movements. prominent symptom in parkinson's disease.
absence or reduction in voluntary movements.
deep brain stimulation
the electrical stimulation of brain structures via an implanted electrode. used for parkinson's disease treatment.
sustained muscle action, slower acting
fast acting initial motor responses
gamma motor neurons
stimulate intrafusal fibers in muscle spindle. when stretched by relaxation of muscle, the annulospiral receptor is activated
Contraction of one set of muscles (i.e., flexors) inhibits the contraction of the antagonistic group (extensors). When a flexor is activated, the alpha motor neuron sends axonal branches to inhibitory neurons in the spinal cord that act to suppress the stretch reflex in the antagonistic extensor muscle. This overrides the influence of the annulospiralreceptors activated in the relaxed extensor muscle. Conscious intent can override reciprocal inhibition as evidenced by isometric contractions.
Withdrawal reflex can activate extensor on other side.
An example of this is when a person steps on a nail, the leg that is stepping on the nail pulls away, while the other leg takes the weight of the whole body
Axons from receptors in the skin terminate directly on the dendrites of motor neurons. A painful stimulus stimulates an axon potential in the axon of the receptor, which causes excitatory neurotransmitter molecules to be released into the synapse. The motor neurons become excited and initiate muscle contractions that pull the limb away from the noxious stimulus.
neurotransmitter released by alpha motor neurons to cause muscle contractions
Stretching the muscle spindle causes the annulospiral receptor to be stretched. When stretched it gets excited and an axon action potential travels down its axon to the spinal cord where the axon terminates on several motor neurons. The motor neurons then become excited and stimulate contractions of fibers in the muscle. When stretched in a muscle the muscle contracts
golgi tendon organ
golgi tendon organs, which are stretch receptors that are located in the tendons, stimulate inhibitory cells in the spinal cord, which inhibit firing of motor neurons to prevent over contraction (occurs during vigorous contracting of the muscle)
spinal pattern generators
Neural networks that produce rhythmic patterned outputs (without sensory feedback).
our conceptual knowledge is grounded in our knowledge of our own body, notion of self- reference
Seen in patients with Huntington's disease. It is involuntary motor movements, ballism. Too little inhibition by the basal ganglia. They gradually dominate normal motor function. Patient may adopt contorted postures with arms and legs, trunk and head in constant motion.
Area 8- the frontal eye fields
Includes the frontal eye fields, a region that contribute to the control of the eye movements
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