CNS Organization Flashcards
What happens if you disconnect at the hindbrain?
A low decerebrate animal
What structure compose the hindbrain?
Cerebellum, medulla, and pons
Describe the state of a low decerebrate animal.
Unconscious, incapable of purposeful activity. Sensory input from head (cranial nerves 4-12) can’t reach cerebrum. Inactive without stimulation. No thermoregulation.
What would we call the state of a low decerebrate human?
Persistent vegetative state
What is the disconnection between the thalamus and the midbrain?
High decerebrate disconnection
Describe the state of a high decerebrate animal.
Can walk, climb, run, and stand when stimulated. May attack moving objects, but bump into stationary ones. Capable of grooming, chewing food, and drinking.
What is a high decerebrate baby (e.g., anencephalic) capable of?
Gazing, sucking, crying, visual tracking, and stretching
What kind of posturing is caused by damage to the upper brainstem?
Decerebrate posturing
decerebrate posturing (n.)
hands adducted and extended, wrists pronated, fingers flexed; legs are stiffly extended, with plantar flexion
What kind of posturing is caused by damage to one or both corticospinal tracts?
Decorticate posturing
decorticate posturing (n.)
arms are adducted and flexed, with wrists and fingers flexed on chest; legs are stiffly extended and medially rotated, with plantar flexion
What is disconnection act the thalamus called?
Diencephalic disconnection
Describe an animal with diencephalic disconnection.
behavior is not motivated or voluntary; exhibit “sham-rage” and other sympathetic arousal activity; capable of thermoregulation; intact sense of smell
What is disconnection of the cortex called?
Decorticate disconnection
Describe an animal with decorticate disconnection.
normal sleep-wake cycle; superficially normal behavior; no biologically adaptive behavior; conditioning intact; no planning or prospective behavior
The brain can be subdivided on the basis of cell types into the following four categories:
Primary sensory cortex, primary motor cortex, association (secondary) areas, higher-order (tertiary) areas
Are spiny neurons typically excitatory or inhibitory?
Excitatory
Are aspiny neurons typically excitatory and inhibitory?
Inhibitory
What are the neurotransmitters typically used by spiny neurons?
Glutamate and aspartate
What percentage of synapses are found on spines?
95%
What are two major classes of spiny neurons?
Pyramidal cells and stellate cells
Describe aspiny neurons.
Interneurons with short axons and no dendritic spines
cortical layers II and III (n.)
primarily receive afferent neurons from other regions of the cortex
cortical layer IV (n.)
primarily receives afferent sensory neurons from other parts of the brain
cortical layers V and VI (n.)
have efferent neurons to other parts of the brain
Pyramidal cells are mostly in layers ____, ____, ____, and ____.
II, III, V, and VI
