Learning & Memory

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

Brain Structures & their Functions

8-40

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

Hindbrain

Contains pons, cerebellum & medulla

pons

medulla

cerebellum

8-47

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

8-52

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

8-57

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

Brain Structures & their Functions

8-40

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

Hindbrain

Contains pons, cerebellum & medulla

pons

medulla

cerebellum

8-47

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

8-52

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

8-57

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.