Cerebellar Comparator Function
Figure 14-36 Motor cortex sends nerve impulses down the brain stem, some go to cerebellum, the rest of them go down to lower areas of the spinal cord to go to the skeletal muscles which send feedback to the cerebellum. Cerebellum very important to carry out fine motor movements.
Basal Nuclei and Cerebellar dysfunction
Both help control motor functions but have opposite effects
Basal nuclei dysfunction
results in increased muscle tone and resting tremor
results in balance impairment, decreased muscle tone, and intention tremor.
Reticular Activating System
Part of the reticular formation that receives input from the cerebrum, optic, trigeminal, and vestibulocochlear nerves to maintain mental alertness. Damage to this can result in a coma. Anesthetics and tranquilizers depress it. Smelling salts (ammonia capsules) stimulate it via the trigeminal nerve
is a network, spread around and throughout the brainstem, many locations. Regulates heart rate, respiration, etc.
normally in left cerebral cortex
Sensory speech connected by arcuate fasiculus to Broca's area
Motor speech (formulate words)
a bundle of neurons that connect the Wernicke and Broca's areas
Absent or defective speech or language comprehension
A lesion in Wernicke's area causes defective auditory and visual comprehension of language, defective naming of objects, and repetition of phrases or sentences.
speak fluently, but unintelligibly.
A lesion in the tracts between Wernicke's area and Broca's area can cause a person with good comprehension not to be able to repeat what was understood.
fluent, but circular speech resulting from a lack of ability to find words because of isolation from the association areas in the temporal and parietal lobes.
hesitant and distorted speech caused by a lesion in Broca's area.
information exchanged via this commisure from the left hemisphere of the brain to the right
sometimes a person suffering a stroke that affects the right parietal lobe may lose the ability to recognize faces. More severe lesions can result in the failure to be able to identify other simple objects. It may cause that person to ignore things on their left side.
Record of brain's electrical activity
Brain wave patterns
alpha, beta, theta, and delta
Alpha brain waves
Resting state with eyes closed
Beta brain waves
During intense mental activity
Theta brain waves
Occur in children but also in adults experiencing frustration or brain disorders
Delta brain waves
Occur in deep sleep, infancy, and severe brain disorders
Very short-term retention of sensory input lasting from a few seconds to several minutes. The kind that is most likely to be lost.
Short term memory
Usually about seven bits of information are stored at a time and retained for few seconds to a few minutes.
Long term memory
explicit (declarative, retaining facts) or implicit (procedural, learned skills)
Explicit long term memory
Retention of facts, lost over time, accessed by hippocampus and amygdaloid nuclear complex (adds emotional overtones)
Implicit long term memory
Learned skills, small amount lost over time
places where parts of explicit memories are stored. Different holes for each part of an event or situation.
Long-term potentiation steps
1.An increase in the production of the neurotransmitter glutamate. 2.An increase in the number of glutamate receptors in the postsynaptic membrane.3. An influx of calcium ions into the postsynaptic cell.4. The activation of calmodulin by calcium ions.5. Calmodulin through cAMP stimulates the synthesis of specific proteins that are involved in changing the cells shape.6. Changes in cell shape is made more permanent by production of a new cytoskeleton, which makes the memory more or less permanent.
Inflammation of the brain.
Transmitted by the bite of an infected animal.
Caused by degeneration of the myelin sheath. Possibly involves autoimmune response to viral infection.
may be caused by a viral infection, but usually by bacteria.
A condition which develops in children following a viral infection, especially chickenpox or influenza. The use of aspirin to reduce the symptoms has been shown to cause the development of the syndrome. Symptoms include nausea, lethargy, and can progress to swelling of the brain cells, coma, brain damage, and even death.
A hereditary neurodegenerative disease most common in Jewish people from eastern Europe. Deficiency of Hexoseaminidase A (enzyme that breaks down gangliosides).
may result in loss of the ability to carry out skilled movements as would be required by a surgeon or a dentist. Caused by a lesion in the premotor area.
also called prefrontal lobotomy. Was used in times past to treat psychiatric patients to reduce aggression. Later studies showed that it was ineffective and had other possible side affects that were undesirable, i.e. epilepsy, lack of inhibition, or loss of initiative.
Disorders involving basal nuclei resulting in jerky, purposeless movements. The general term for disorders that cause involuntary and uncontrolled movements.
one of the more common types of dyskinesias resulting from brain damage in development or the birth process. Causes uncoordinated movements including athetosis, slow writhing, grimacing movements particularly involving the face, neck, and tongue muscles. Difficulty in speaking and swallowing are characteristic.
Sydenham's chorea, commonly called St. Vitus dance
is a disorder caused by toxic or infectious agents temporarily disabling the corpus striatum resulting in uncontrollable shaking.
a hereditary disorder that causes the progressive degeneration of the corpus striatum.
Associated with the malfunction of the Basal Nuclei
a degeneration of the dorsal roots and dorsal column of the spinal cord resulting in a wasting away. It is caused by an untreated syphilis infection.
CVA or cerebrovascular accident caused by hemorrhage, thrombosis, embolism.
Dilation or ballooning of an artery that may burst causing blood to leak into the epidural, subdural, subarachnoid spaces, or the brain tissues. Blood is toxic to brain tissue causing brain tissue damage.
pressure on the brain caused by edema, hematomas, tumors, or hydrocephalus. Abnormal intracranial pressure can result in damage to brain tissue.
Severe type of dementia caused by a decrease in the number of brain neurons resulting in the decrease in brain size. The gyri narrow and the sulci widen.
Group of brain disorders that have seizures. Aseizure is a sudden neuronal discharge. Normally a balance exists between excitation and inhibition and when this balance is disrupted by increased excitation or decreased inhibition it may result in a seizure. The sudden neuronal discharge may result in involuntary muscle contractions causing convulsing.
Attention deficit disorder and attention deficit/hyperactivity disorder
The neurological basis for these disorders is yet unknown. Symptoms include short attention spans and in hyperactivity disorder fidgetiness, excessive talking, and interruptive. Symptoms usually occur before age seven.
loss of the ability to read. Thought to be associated with a lesion in the visual association cortex.
If a persons reading ability is beneath their overall Intelligence. Symptoms are inversion of letters within words and being unable to differentiate between b's and d's, and lack of orientation in three dimensional space.
Means by which the brain receives information about the environment and body
Distributed over large part of the body. Can be somatic (touch, pressure, temperature, proprioception, pain) or visceral (internal organs and consists mostly of pain and pressure)
Smell, taste, sight, hearing, balance
Sensation or perception
Conscious awareness of stimuli received by sensory receptors
Sense compression, bending, stretching of cells
Sense smell and taste
Sense light as vision
Associated with skin
Associated with organs, detect pain and pressure in organs of the body
Associated with joints, tendons
Free Nerve Endings
Simplest and most common type of sensory receptors involved in the detection of pain, temperature, itch, and movement
About 10-15 times more numerous than warm receptors: stimulated by temperatures between 12-35 degrees C
Stimulated at 25-47 degrees C
Stimulated between 0-12 degrees C and above 47 degrees C. Are both nociceptors and free nerve endings.
Have axonal branches with flattened expansions associated with specialized epithelial cells; detect light touch and superficial pressure
Hair follicle receptors
Very sensitive to light touch and superficial pressure but not very localized
Lamellated corpuscles in the deep dermis, hypodermis, and joints; detect deep cutaneous pressure, vibrations, and proprioception
Ruffini end organs
found in the dermis of the fingers primarily; respond to continuous touch or pressure
Tactile corpuscles in the dermal papillae most numerous in the tongue and fingertips. Involved in two-point discrimination
Located in skeletal muscles and provide information about the length of the muscle. Important in control and tone of postural muscles (increased by stretch reflex)
Golgi tendon organs
Proprioceptive receptors activated by an increase in tendon tension caused by contraction or by passive stretch of tendon
Interaction of a stimulus with sensory receptor produces a graded potential
Have axons that can conduct action potential in response to receptor potential
Have no axons and receptor potentials produced do not result in action potentials directly, but cause the release of neurotransmitters that cause action potentials if threshold is reached
Accommodation or adaptation
Decreased sensitivity to a continued stimulus
Provide information about the precise position and the rate of movement of various body parts
Slowly adapting proprioceptors that generate action potentials as long as a stimulus is applied and accomodate very slowly
Rapidly adapting proprioceptors are most sensitive to changes in stimuli
Type of information transmitted (which sense: smell, taste, hearing...)
Sensory Nerve Tracts
Transmit action potentials from periphery to the brain. Each pathway is involved with specific modalities (1st half of word indicates origin, 2nd half termination)
Conveys cutaneous sensory information to the brain. Primary neurons -> interneurons -> secondary neurons -> axons cross to opposite side of spinal cord to thalamus synapsing with tertiary neurons -> somatic sensory cortex. Divided into lateral (pain, temperature) and anterior (light touch, pressure, tickle, itch)
Joins the spinothalamic tract in the midbrain. Consists of afferent fibers of the trigeminal nerve along with a few tactile afferent fibers from the ear and tongue from cranial nerves VII, IX, and X
Spinoreticular and Spinomesencephalic tracts
Ascent with the spinothalamic tract but then divert to join the reticular area or the midbrain
Included with the spinomesencephalic tract and ends in the superior colliculi of the midbrain. Involved in reflexes that turn the head.
One of two major systems that convey cutaneous snesory info to the brain. Includes spinothalamic, spinoreticular, and spinomesencephalic tracts.
Some neurons do not cross over but ascent on the ipsilateral (same side) of the spinal cord on which they enter; unlike the spinothalamic
Carries sensations of two-point discrimination, proprioception, pressure, and vibration. Two tracts: Fasciculus gracilis (sensations from below midthoracic level) and Fasciculus cuneatus (above midthorax)
Carry proprioceptive info to cerebellum. Tracts: Posterior (from thoracic and upper lumbar, extend to cerebellum) and Anterior (carries info from lower trunk and limbs)
Primary somatic sensory cortex
General sensory area. Makes up most of the precentral gyrus of the cerebral cortex. Contains upper motor neurons.
Sensation in one region of the body that is not the source of the stimulus
Occurs in people who have appendage amputated or structure removed such as a tooth
Not a response to immediate direct tissue injury. May be intensified by stress, anxiety, or depression, or by peripheral sensitization or central sensitization
Primary Motor cortex
Another name for postcentral gyrus. Also primary motor area; contains upper motor neurons.
located anterior to the primary motor cortex; staging area for motor functions. Contains upper motor neurons.
located anterior to the premotor area; involved with motivation and foresight to plan and initiate movements and complexity of emotional behavior, mood, and motivation
Descending tracts that carry action potentials from the cerebrum or cerebellum to the brainstem or spinal cord
Direct pathway, controls fine movements and muscle tone; manual dexterity, upper motor neurons synapse directly with lower
Indirect pathway, controls "primitive" movements of trunk and proximal portions of limbs, synapse in some intermediate nucleus. Tracts: rebrospinal, vestibulospinal, recticulospinal, tectospinal
Coricospinal tract (direct)
Descending spinal pathway, movements below the head
Anterior tract (direct)
Descending spinal pathway, supplies neck and trunk
Lateral tract (direct)
Descending spinal pathway, supplies all levels of body
Corticobulbar tract (direct)
Descending spinal pathway, supplies head and face movements
decussate in midbrain and descends in lateral column of spinal cord
descends down anterior column to synapse with interneurons and lower motor neurons in ventromedial portion of spinal cord gray matter
descending pathway; muscle tone and posture via trunk muscles and proximal limb muscles.
Extends from superior colliculi of mesencephalon to spinal cord; controls reflex movements of the head
Largest in cerebrum, complex neural circuits that connect the nuclei with each other, the thalamus, and cerebral cortex; stimulatory and inhibitory
Facilitate muscle activity
Facilitate muscle activity by inhibiting antagonist muscles; also help muscles to relax during rest
Flocculonodular node; receives input from vestibule of inner ear; helps control balance during movement and coordinate eye movement
Vermis & medial parts of the lateral hemispheres; Enables fine motor coordination for simple movements via the comparator function
Later parts of the later hemispheres; communicates with motor, premotor, and prefrontal areas via cerebral peduncles to carry out rapid and complex motor movements
"on the same side" DO NOT decussate
"on the other side" DO decussate