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Memory
Involves a number of regions in brain Amnesia (memory loss) studies reveal
separate short- & long-term memory systems
8-35
Memory continued
Hippocampus is critical for acquiring new memories & consolidating
short- into long-term memory
Amygdala is crucial for fear memories
Prefrontalcortex
8-36
Memory continued
Storage of memory is in cerebral hemispheres
Higher order processing & planning occur in prefrontal cortex
Prefrontalcortex
Memory
Short-term: Memory of recent events.
Medial temporal lobe: consolidates short term into long term memory.
Hippocampus is critical component of memory.
Acquisition of new information, facts and events requires both the medial temporal lobe and hippocampus.
Memory
Long-term: Requires activation of genes, leading to
protein synthesis. Growth of dendritic spines. Formation of new synaptic connections.
Cerebral cortex stores factual information.
Prefrontal lobes involve retrieval of parts of memories from different areas of the brain to use as a whole.
Long-Term Potentiation (LTP)
Is increased excitability of a synapse after high frequency stimulation
Glutamate activates AMPA& NMDA postsynaptic receptors in hippocampus
8-37
Glycine or serine must coactivate NMDA receptors, opening Ca2+
channels Presynaptic Ca2+ levels also
increase during LTP causing increased NT release
Caused by NO released by postsynaptic cell which diffuses to presynaptic
High postsynaptic Ca2+
causes LTP & growth of dendritic
spines LTP is thought to be a form
of synaptic learning
Long-Term Potentiation (LTP) continued
8-38
Neurogenesis in Hippocampus
Appears to be crucial for learning & memory
Hippocampus contains neural stem cells that continually produce new neurons (neurogenesis)
Stress or depression impede learning & cause hippocampus to shrink Stress reduction & antidepressants return size
to normal8-39
Thalamus Comprises the
majority of the diencephalon.
Forms most of the walls of the 3rd ventricle.
Acts as relay center for all sensory information (except olfactory) to the cerebrum
Thalamus continued
Plays role in level of arousal
Epithalamus contains choroid plexus which secretes CSF Also contains pineal
gland which secretes melatonin
Involved in sleep cycle & seasonal reproduction
Hypothalamus
Is most important structure for homeostasis
Contains neural centers for hunger, thirst, body temperature
Regulates sleep, emotions, sexual arousal, anger, fear, pain, & pleasure
Controls hormone release from anterior pituitary
Produces ADH & oxytocin Coordinates sympathetic &
parasympathetic actions 8-42
Pituitary Gland
Is divided into anterior & posterior lobes
Posterior pituitary stores & releases ADH (vasopressin) & oxytocin Both made in
hypothalamus & transported to pituitary
Hypothalamus produces releasing & inhibiting hormones that control anterior pituitary hormones
8-43
Circadian Rhythms
Are body's daily rhythms Regulated by hypothalamus
The master clock Adjusted daily by light from eyes Controls pineal gland secretion of melatonin
which regulates circadian rhythms
8-44
Midbrain
Contains: Superior colliculi -- involved in visual
reflexes Inferior colliculi -- relays for auditory info
8-45
Midbrain Contains:
Corpra quadrigemina Cerebral peduncles Substantia nigra Red nucleus
Functions: Visual reflexes. Relay center for auditory information. Motor coordination.
Red nucleus & substantia nigra -- involved in motor coordination
S. nigra dopamine neurons degenerate in Parkinson’s Mesolimbic dopamine neurons are involved in reward &
addiction
Contains several nuclei of cranial nerves
& 2 important respiratory control centers Apneustic &
pneumotaxic centers
Hindbrain - Pons
8-48
2nd largest structure in brain Receives input from proprioceptors (joint, tendon, &
muscle receptors) Involved in coordinating movements & motor learning
Hindbrain - Cerebellum
cerebellum
8-49
Contains all tracts that pass between brain & spinal cord
& many nuclei of cranial nerves
& several crucial centers for breathing & cardiovascular systems
Hindbrain - Medulla
8-50
Is complex network of nuclei & fibers spanning medulla, pons, midbrain, thalamus, & hypothalamus
Functions as reticular activating system Sets level of arousal of
cerebral cortex to incoming sensory information
Reticular Formation
8-51
Spinal Cord Tracts
Sensory info from body travels to brain in ascending spinal tracts
Motor activity from brain travels to body in descending tracts
8-53
Ascending Spinal Tracts
Ascending sensory tracts decussate (cross) so that brain hemispheres receive info from opposite side of body
Same for most motor tracts from brain
8-54
Peripheral Nervous System (PNS)
Consists of nerves that exit from CNS & spinal cord, & their ganglia (= collection of cell bodies outside CNS)
8-58
Cranial Nerves
Consist of 12 pairs of nerves 2 pairs arise from neurons in forebrain 10 pairs arise from midbrain & hindbrain
neurons Most are mixed nerves containing both
sensory & motor fibers
8-59
Spinal Nerves Are mixed nerves that separate next to
spinal cord into dorsal & ventral roots Dorsal root composed of sensory fibers Ventral root composed of motor fibers
8-60
Reflex Arc
Stimulation of sensory receptors evokes AP that are conducted into spinal cord.
Synapses with motor neuron.
Conducts impulses to muscle and stimulates a reflex contraction.
Brain is not directly involved.
Memory
Involves a number of regions in brain Amnesia (memory loss) studies reveal
separate short- & long-term memory systems
8-35
Memory continued
Hippocampus is critical for acquiring new memories & consolidating
short- into long-term memory
Amygdala is crucial for fear memories
Prefrontalcortex
8-36
Memory continued
Storage of memory is in cerebral hemispheres
Higher order processing & planning occur in prefrontal cortex
Prefrontalcortex
Memory
Short-term: Memory of recent events.
Medial temporal lobe: consolidates short term into long term memory.
Hippocampus is critical component of memory.
Acquisition of new information, facts and events requires both the medial temporal lobe and hippocampus.
Memory Long-term:
Requires activation of genes, leading to protein synthesis.
Growth of dendritic spines. Formation of new synaptic connections.
Cerebral cortex stores factual information.
Prefrontal lobes involve retrieval of parts of memories from different areas of the brain to use as a whole.
Long-Term Potentiation (LTP)
Is increased excitability of a synapse after high frequency stimulation
Glutamate activates AMPA& NMDA postsynaptic receptors in hippocampus
8-37
Glycine or serine must coactivate NMDA receptors, opening Ca2+ channels
Presynaptic Ca2+ levels also increase during LTP causing increased NT release
Caused by NO released by postsynaptic cell which diffuses to presynaptic
High postsynaptic Ca2+
causes LTP & growth of dendritic
spines LTP is thought to be a
form of synaptic learning
Long-Term Potentiation (LTP) continued
8-38
Neurogenesis in Hippocampus
Appears to be crucial for learning & memory
Hippocampus contains neural stem cells that continually produce new neurons (neurogenesis)
Stress or depression impede learning & cause hippocampus to shrink Stress reduction & antidepressants return size
to normal8-39
Thalamus Comprises the
majority of the diencephalon.
Forms most of the walls of the 3rd ventricle.
Acts as relay center for all sensory information (except olfactory) to the cerebrum
Thalamus continued
Plays role in level of arousal
Epithalamus contains choroid plexus which secretes CSF Also contains pineal
gland which secretes melatonin
Involved in sleep cycle & seasonal reproduction
Hypothalamus Is most important structure
for homeostasis Contains neural centers for
hunger, thirst, body temperature
Regulates sleep, emotions, sexual arousal, anger, fear, pain, & pleasure
Controls hormone release from anterior pituitary
Produces ADH & oxytocin Coordinates sympathetic &
parasympathetic actions 8-42
Pituitary Gland
Is divided into anterior & posterior lobes
Posterior pituitary stores & releases ADH (vasopressin) & oxytocin Both made in
hypothalamus & transported to pituitary
Hypothalamus produces releasing & inhibiting hormones that control anterior pituitary hormones
8-43
Circadian Rhythms
Are body's daily rhythms Regulated by hypothalamus
The master clock Adjusted daily by light from eyes Controls pineal gland secretion of melatonin
which regulates circadian rhythms
8-44
Midbrain
Contains: Superior colliculi -- involved in visual
reflexes Inferior colliculi -- relays for auditory info
8-45
Midbrain Contains:
Corpra quadrigemina Cerebral peduncles Substantia nigra Red nucleus
Functions: Visual reflexes. Relay center for auditory information. Motor coordination.
Red nucleus & substantia nigra -- involved in motor coordination
S. nigra dopamine neurons degenerate in Parkinson’s Mesolimbic dopamine neurons are involved in reward &
addiction
Contains several nuclei of cranial nerves
& 2 important respiratory control centers Apneustic &
pneumotaxic centers
Hindbrain - Pons
8-48
2nd largest structure in brain Receives input from proprioceptors (joint, tendon, &
muscle receptors) Involved in coordinating movements & motor learning
Hindbrain - Cerebellum
cerebellum
8-49
Contains all tracts that pass between brain & spinal cord
& many nuclei of cranial nerves
& several crucial centers for breathing & cardiovascular systems
Hindbrain - Medulla
8-50
Is complex network of nuclei & fibers spanning medulla, pons, midbrain, thalamus, & hypothalamus
Functions as reticular activating system Sets level of arousal of
cerebral cortex to incoming sensory information
Reticular Formation
8-51
Spinal Cord Tracts
Sensory info from body travels to brain in ascending spinal tracts
Motor activity from brain travels to body in descending tracts
8-53
Ascending Spinal Tracts Ascending sensory tracts
decussate (cross) so that brain hemispheres receive info from opposite side of body
Same for most motor tracts from brain
8-54
Peripheral Nervous System (PNS)
Consists of nerves that exit from CNS & spinal cord, & their ganglia (= collection of cell bodies outside CNS)
8-58
Cranial Nerves
Consist of 12 pairs of nerves 2 pairs arise from neurons in forebrain 10 pairs arise from midbrain & hindbrain
neurons Most are mixed nerves containing both
sensory & motor fibers
8-59
Spinal Nerves Are mixed nerves that separate next to spinal cord
into dorsal & ventral roots Dorsal root composed of sensory fibers Ventral root composed of motor fibers
8-60
Reflex Arc
Stimulation of sensory receptors evokes AP that are conducted into spinal cord.
Synapses with motor neuron.
Conducts impulses to muscle and stimulates a reflex contraction.
Brain is not directly involved.