Neurobiology: Neuroanatomy - Test 2

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From Neuron to Brain
Chapters 17, 19-22, 24
Test March 1st, 2013 with Tim E. Van Meter
updated 9 years ago by lifesurfeit
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1

Photoreceptor

A specialized cell in the retina that transduces light energy into changes in membrane potential.

2
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Rod cell

Photoreceptor containing rhodopsin, concerned with low light vision. Connected to bipolar cells.

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Cone cell

Photoreceptor in the retina used in daylight vision containing one of three photopigments to see colors. Connected to bipolar cells. Concentrated in the fovea.

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Bipolar cell

Rods and cones (photoreceptors) are connected to these ___ cells that transmit graded signals to ganglion cells.

5

D-type (ON) bipolar cell

A bipolar cell of the retina that depolarizes in response to light (light ON) in the center of its receptive field.

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H-type (OFF) bipolar cell

A bipolar cell of the retina that depolarizes in response to dark (light OFF) and hyperpolarizes in response to light in the center of its receptive field.

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Retinal ganglion cell

Neuron located near the inner surface (the ganglion cell layer) of the retina of the eye. It receives visual information from photoreceptors via bipolar cells and amacrine cells and transmits this information to several regions in the thalamus, hypothalamus, and mesencephalon, or midbrain Two types: M- & P- type. Have action potentials. Their long axons form the optic chiasm, optic nerve and optic tract.

8

Photosensitve retinal ganglion cell

Contain their own photopigment, melanopsin, which makes them respond directly to light even in the absence of rods and cones. They project to, among other areas, the suprachiasmatic nucleus (SCN) via the retinohypothalamic tract for setting and maintaining circadian rhythms.

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Amacrine cell

Intervening interneuron in the retina of the eye that projects neurites laterally in the inner plexiform layer. Makes predominantly lateral connections. Inhibitory, modulates signals. Some have action potentials.

10

Horizontal cell

A cell in the retina of the eye that
projects neurites laterally in the outer plexiform
layer. Makes predominantly lateral connections, transmits modulatory signals.

11

Pathway of light through cell layers

Photoreceptor -> bipolar cell -> ganglion cell -> optic nerve
(horizontal and amacrine cells modify the responses of bipolar and ganglion cells)

12

Pathway through optic tract

RGCs project to the lateral geniculate nucleus of the thalamus (LGN), synapse and neurons project on to the primary visual cortex (V1) in the occipital lobe. Further processing via other cortical areas.
Information conveyed includes shape, movement, color, fine detail

13

Locally graded vs. action potential retinal cells

Locally graded: photoreceptors, horizontal and bipolar cells
Action potentials: Ganglion cells and amacrine cells.

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Glial cells of the retina

Muller cells and astrocytes.

15

Fovea

The pit or depression in the center of the retina containing a high concentration of cone cells (no rods) that constitutes a small blind spot in dim light. In humans, specialized for high acuity vision.

16

Optic disc

The location on the retina where the optic nerve fibers leave the eye (blind spot).

17

Optic nerve

The bundle of retinal ganglion cell axons that passes from the eye to the optic chiasm.

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Optic chiasm

The structure in which the right and left optic nerves converge and partially cross to form the optic tracts.

19

11-cis-retinal

Stable form of retinal bound to opsin (together, rhodopsin) when there is no light.

20

Primary visual cortex (V1)

Aka striate cortex, located at the pole of the occipital lobe

21

Three principal features of photoreceptor structure

1) Outer segment within which light is absorbed by visual pigment,
2) Inner segment containing organelles and ion pumps, and
3) Synaptic terminal which releases glutamate to second-order cells and which also receives synaptic inputs.

22

In the dark (at rest), the photoreceptor is ____ by a continuous inward current flowing into the outer segment.

depolarized

23

Light turns off the ongoing inward current, allowing the outward ____ current to ____ the cell.

potassium; hyperpolarize

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Rhodopsin

Photopigment in rods

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Muller cell

Glial cells of the retina, modulate synapse function, sequester neurotransmitters, ionic balance.

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Lateral geniculate nucleus (LGN)

A thalamic nucleus that relays information from the retina to the primary visual cortex.

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Suprachiasmatic nucleus (SCN)

A small nucleus of the hypothalamus just above the optic chiasm that receives retinal innervation and synchronizes circadian rhythms with the daily light-dark cycle.

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Pulvinar nucleus

A mass of neurons in the posterior thalamus that have widespread reciprocal connections with areas across the cerebral cortex.

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cGMP

Secondary messenger in phototransduction in the eye. In the photoreceptors of the mammalian eye, the presence of light activates phosphodiesterase, which degrades ___. The sodium ion channels in photoreceptors are ___-gated, so degradation causes sodium channels to close, which leads to the hyperpolarization of the photoreceptor's plasma membrane and ultimately to visual information being sent to the brain

30

Transducin

The G-protein that couples rhodopsin to
the enzyme phosphodiesterase in rod photoreceptors

31

Visual pigment molecules consist of:

1) opsin (protein) and
2) retinal (chromophore)

32

Chromophore

Chemical group producing color in a compound.

33

M-type

Larger magnocellular retinal ganglion cell.

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P-type

Smaller parvocellular retinal ganglion cell.

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Depolarized ___ get hyperpolarized, changing ___ release ____ cells which transmit signals across a synapse to ____. (Modulated by ___ cells by ___)

(In response to light) photoreceptors, glutamate, bipolar cells, horizontal, GABA, RGC's

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Three meningeal layers

(1) Dura mater, (2) arachnoid mater, and (3) pia mater.

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Dura mater

Thick outer connective tissue layer.

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Arachnoid mater

Fluid filled cushion, highly vascularized.

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Pia mater

Delicate inner layer contacting brain surface.

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Lateral ventricles

Large lateral fluid filled canals in the middle of the large hemispheres of the brain. Related to cerebral cortex and basal telencephalon.

41

Choroid plexus

Specialized secretory tissue in ventricles that makes cerebrospinal fluid.

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Third ventricle

Small centralized CSF canal that connects the lateral ventricles to the fourth ventricle. Related to thalamus & hypothalamus.

43

CN innervation controls sense of smell (Olfaction)

CN I (Olfactory)

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CN nerves control visual perception and eye movements

CN II (Optic) ,III (Oculomotor), IV (Trochlear) and VI (Abducens)

45

Cranial nerve responsible for hearing and balance

CN VIII (Vestibulo-cochlear, as called Auditory/Vestibular)

46

Cranial nerves are responsible for the sense of taste

CN VII (Facial) and CN IX (Glossopharyngeal), anterior and posterior tongue, respectively

47

Cranial nerves control the muscles of the head and neck, tongue and their sensations

CN V (Trigeminal), VII (Facial), IX (Glossopharygeal) , X (Vagus), XI (Accessory) and XII (Hypoglossal)

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One cranial nerve extends into the enteric system to innervate the gut and also controls swallowing

CN X (Vagus Nerve)

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Cranial nerves (list)

I. Olfactory, II. Optic, III. Ocular motor, IV. Trochlear, V. Trigeminal, VI. Abducens, VII. Facial, VIII. Vestibular, IX. Glossopharyngeal, X. Vagus, XI. Accessory, XII. Hypoglossal

50

Cranial nerves: sensory, motor or both? (all)

I. Olfactory - Sensory, II. Optic - Sensory, III. Ocular motor - Motor, IV. Trochlear - Motor, V. Trigeminal - Both, VI. Abducens - Motor, VII. Facial - Both, VIII. Vestibular - Sensory, IX. Glossopharyngeal - Both, X. Vagus - Both, XI. Accessory - Motor, XII. Hypoglossal - Motor

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Afferent

Axon conducting impulses toward the central nervous system, usually relays sensory information.

52

Efferent

Axon conducting impulses outward from the central nervous system, usually relays motor signals.

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Cranial nerve I

Olfactory nerve - sense of smell (sensory)

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Cranial nerve II

Optic nerve - vision (sensory)

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Cranial nerve III

Oculomotor nerve - eye movements; papillary constriction and accomodation; muscles of the eyelid (motor)

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Cranial nerve IV

Trochlear nerve - eye movements (motor)

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Cranial nerve V

Trigeminal nerve - somatic sensation of the face, mouth, cornea; muscles of mastication (both sensory and motor)

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Cranial nerve VI

Abducens nerve - eye movements (motor)

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Cranial nerve VII

Facial nerve - controls muscles of facial expression; taste from anterior tongue; lacrimal (tear) and salivary glands (both sensory and motor)

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Cranial nerve VIII

Auditory/Vestibular nerve - hearing; sense of balance (sensory)

61

Cranial nerve IX

Glossopharyngeal nerve - sensation from pharynx; taste from posterior tongue; carotid baroreceptors (both sensory and motor)

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Cranial nerve X

Vagus nerve - autonomic functions of the gut; sensation from pharynx; muscles of vocal cords; swallowing (both sensory and motor)

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Cranial nerve XI

Accessory nerve - shoulder and neck muscles (motor)

64

Cranial nerve XII

Hypoglossal nerve - movements of tongue (motor)

65

Cerebrospinal fluid (CSF)

Protective cushion and circulates metabolytes; clears toxins for venous drainage; maintains ionic & pH balance

66

Subarachnoid space

Filled with salty, clear liquid; squishy cushion between supportive membranes inside of skull (dura) and the surface of the brain (pia)

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CSF path (flow)

Cerebrum -> brain stem core -> subarachnoid space -> special structures called arachnoid villi absorb CSF

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Fourth ventricle

Small centralized CSF canal that connects the third ventricle to the spinal canal running the length of the spinal cord. Related to cerebellum, pons, and medulla.

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Cerebral aqueduct

Related to tectum and midbrain tegmentum.

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Blood supply to spinal cord (2)

Vertebral arteries & medullary arteries

71

Medullary arteries

Arise from segmental branches of aorta; form anterior & posterior spinal arteries; lesions?

72

Blood supply to brain (2)

Internal carotids & vertebral arteries

73

Major arteries of the brain

Circle of Willis, anterior circulation: anterior cerebral and middle cerebral, posterior circulation: posterior cerebral/basilar/vertebral, anterior cerebellar, anterior inferior cerebellar, posterior inferior cerebellar

74

Central sulcus

The sulcus (groove) in the cerebrum that divides the frontal lobe from the parietal lobe (between precentral and postcentral gyri).

75

Cerebrum

The largest part of the forebrain; also called telencephalon. Divided into the frontal, parietal, occipital and temporal lobes.

76

Precentral gyrus

Lies immediately anterior to the central sulcus (posterior frontal); its neurons control voluntary movement

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Postcentral gyrus

Lies immediately posterior to the central sulcus (anterior parietal); its neurons control somatic sensation (touch)

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Primary motor cortex

Brodmann’s area 4, located on the precentral gyrus; the region of cortex that, when weakly stimulated, elicits localized muscle contractions; also called M1

79

Primary somatosensory cortex

Brodmann’s area 3b located in the postcentral gyrus; also called S1.

80

Corpus callosum

The great cerebral commissure, consisting of axons connecting the cortex of the two cerebral hemispheres.

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Diencephalon

A region of the brain stem derived from the prosencephalon (forebrain). Diencephalic structures include the epithalamus, thalamus and hypothalamus

82

Hypothalamus

The ventral part of the diencephalon, involved in the control of the autonomic nervous system and the pituitary gland.

83

Epithalamus

Dorsal, or farthest to the rear, segment of the diencephalon. In terms of function, responsible for connecting the lymbic system to the rest of the brain, as well as regulating hormones secreted by the pineal gland

84

Pineal gland

Controlled by epithalamus; releases melatonin as part of the retinohypothalamic tract that drives circadian rhythms

85

Habenular nuclei

Small group of nuclei that are part of the epithalamus of the diencephalon, situated at the posterior end of the thalamus, on its upper surface. Pineal gland is attached here; also connects to interpeduncular nucleus.

86

(Dorsal) Thalamus

Makes up 80% of the diencephalon, highly
interconnected with the cerebral neocortex.

87

Subthalamus

Part of the diencephalon. Its major part is the subthalamic nucleus. Develops efferent (output) connections to the striatum in the telencephalon, to the dorsal thalamus in the diencephalon, and to the red nucleus and substantia nigra in the mesencephalon. It receives afferent (input) connections from the substantia nigra and striatum

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Basal ganglia

Collection of associated cell groups (gray matter) nuclei in the middle and base of the brain adjacent to thalamus in the basal forebrain, including the caudate nucleus, putamen, globus pallidus, and subthalamic nuclei, and substantia nigra.
Deep nuclei with widespread connections to several brain structures, including the cortex and limbic system.

89

Striatum

Caudate + Putamen

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Caudate nucleus

Long “tail” shaped nucleus, C shaped, originating in anterior putamen (caudate head) and forming the lateral wall of the lateral ventricle. Posterior end is continuous with the amygdala, which connects back to putamen. Part of basal ganglia, involved in motor control.

91

Putamen

Egg shaped structure at the anterior end of the striatum, adjacent to the thalamus. Part of basal ganglia, involved in motor control.

92

Lenticular nucleus

Putamen + Globus pallidus

93

Globus pallidus

Pale appearace histologically due to concentration of myelinating fibers orginating in, terminating in, and passing through it. Two functionally distinct parts, called the internal (or medial) and external (lateral) segments, abbreviated GPi and GPe. Involved in motor control.

94

Subthalamic nucleus

Only BG structure that produces an excitatory neurotransmitter, Glutamate. The role of the subthalamic nucleus is to stimulate the SNr-GPi complex. Part of basal ganglia, involved in motor control.

95

Substantia nigra

Divided into SNr (reticulata) and SNc (compacta).
SNr often works in unison with GPi, and the SNr-GPi complex inhibits the thalamus. SNc however, produces the neurotransmitter dopamine, which is very significant in maintaining balance in the striatal pathway. Part of basal ganglia, involved in motor control. Damage to this area causes Parkinson's.

96

Hindbrain

The region of the brain derived from the
caudal primary embryonic brain vesicle; also called
rhombencephalon. Structures include the
cerebellum, pons, and medulla.

97

Cerebellum

A structure derived from the rhombencephalon,
attached to the brain stem at the pons;
an important movement control center, having extensive interconnections with the premotor cortex and vestibular system.

98

Vermis

The midline region of the cerebellum, divides the cerebellum into right and left hemispheres. Sends output to the brain stem structures that contribute to the ventromedial descending spinal pathways (which control axial musculature).

99

Flocculum

Small lobe of the cerebellum associated with the nodulus of the vermis; together, these two structures compose the vestibular part of the cerebellum. Receives input at its base from the middle ears vestibular system and regulates balance. Projections descend to the spinal cord and connect to the motor nuclei involved in control of eye movement.

100

Brain stem

The midbrain, pons, and medulla. Relays information from cerebrum to the spinal cord and cerebellum and vice versa. Regulates vital functions and controls cranial nerves.

101

Midbrain

The region of the brain derived from the middle primary embryonic brain vesicle; also called mesencephalon. Midbrain structures include the tectum and the tegmentum. Also contains cerebral aqueduct.

102

Pons

The part of the rostral hindbrain that lies ventral to the cerebellum and the fourth ventricle. Switchboard connecting cerebellum to cerebral cortex.

103

Medulla (oblongata)

The part of the hindbrain caudal to the pons and cerebellum. Contains the vagus nerve.

104

Spinal cord

The part of the central nervous system in
the vertebral column

105

Ventral horn

The ventral region of the spinal cord containing neuronal cell bodies of motor neurons that affect the axial muscles.

106

Dorsal horn

The dorsal region of the spinal cord containing neuronal cell bodies. Includes substantia gelatinosa. Receives several types of sensory information from the body, including light touch, proprioception, and vibration. This information is sent from receptors of the skin, bones, and joints through sensory neurons whose cell bodies lie in the dorsal root ganglion.

107

White matter

Consists mostly of glial cells and myelinated axons that transmit signals from brain to body, superficially located in spinal cord

108

Grey matter

Contains neural cell bodies; in horn areas of spinal cord.

109

Dorsal column

A white matter tract on the dorsal side of the spinal cord, carrying touch and proprioceptive axons to the brain stem.

110

Corticospinal tract

The tract that originates in the neocortex and terminates in the spinal cord; involved in the control of voluntary movement.

111

Rubrospinal tract

A tract originating in the red nucleus and terminating in the spinal cord; involved in the control of movement.

112

Dorsal root ganglion

A collection of cell bodies of the sensory neurons that are part of the somatic PNS. There is one dorsal root ganglion for each spinal nerve.

113

Spinothalamic tract

An ascending somatic sensory pathway traveling from the spinal cord to the thalamus via the lateral spinothalamic columns; mediates information about pain, temperature, and some forms of touch.

114

Typanic membrane

A membrane at the internal end of the auditory canal that moves in response to variations in air pressure; also called eardrum.

115

Ossicles

Malleus, incus, stapes

116

Malleus

An ossicle in the middle ear attached to the
tympanic membrane; shaped somewhat like a hammer.

117

Incus

An ossicle in the middle ear whose shape somewhat
resembles an anvil.

118

Stapes

An ossicle in the middle ear attached to the oval window that somewhat resembles a stirrup

119

Oval window

A hole in the bony cochlea of the inner ear, where movement of the ossicles is transferred to movement of the fluids in the cochlea.

120

Cochlea

A spiral bony structure in the inner ear that
contains the hair cells that transduce sound.

121

Organ of Corti

An auditory receptor organ that contains hair cells, rods of Corti, and supporting cells

122

Inner hair cell

An afferent auditory cell located in the organ of Corti; the primary transducer of sound into an electrochemical signal

123

Outer hair cell

An auditory receptor (efferent) cell located in the organ of Corti in the inner ear.

124

Basilar membrane

A membrane in the cochlea in the inner ear along which the hair cells are located.

125

Tectorial membrane

A acellular gelatinous sheet of tissue that hangs over the organ of Corti in the cochlea in the inner ear through which the sensory hairs of the inner and outer hair cells project.

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Pathway from cochlea to auditory cortex

Cochlea inner hair cells -> vestibular (auditory) nerve -> dorsal and ventral cochlear nuclei (medulla) -> inferior colliculus (midbrain) -> medial geniculate nucleus (thalamus) -> auditory cortex

127

Semicircular canal

A component of the vestibular labyrinth in the inner ear that transduces head rotation.

128

Horizontal semicircular canal

Shortest of the three, movement of the fluid in this canal corresponds to rotation of the head around a vertical axis (neck)

129

Anterior semicircular canal

Movement of the fluid in this canal detects rotation of the head around a rostral-caudal (up-down) axis.

130

Posterior semicircular canal

Movement of the fluid in this canal detects rotations of the head in the sagittal plane (forward-back)

131

Otoliths

The utricle or the saccule, organs of the vestibular labyrinth in the inner ear that transduce head tilt and acceleration

132

Saccule

One of the otoliths; sensitive to vertical acceleration

133

Utricle

One of the otoliths; sensitive to horizontal acceleration

134

Cochlear nerve

Sensory nerve in the head that carries signals from the cochlea of the inner ear to the brain. Part of the vestibulocochlear nerve, the 8th cranial nerve

135

Vestibular nerve

Sensory nerve in the head that carries spatial orientation information from the semicircular canal to the brain. Part of the vestibulocochlear nerve, the 8th cranial nerve

136

Primary auditory cortex (A1)

Brodmann’s area 41, on the superior surface of the temporal lobe

137

Tonotopic map

Spatial arrangement of where sounds of different frequency are processed in the brain. Reflect dedicated areas of sensory processing in the postcentral gyrus and adjacent areas.

138

Pacinian corpuscle

A mechanoreceptor of the deep skin, selective for high-frequency vibrations. Pressure sensor in skin (large receptive field)

139

Ruffini's corpuscle

A slowly adapting mechanoreceptor of shallow skin, sensing pressure or compression

140

Meissner's corpuscle

A rapidly adaptive mechanoreceptor of extraordinary mechanical sensitivity to initial contact and to motion. Found in skin on lips, palm, fingers and sole of the foot.

141

Merkel's disc

A slowly adapting mechanoreceptor that senses pressure and texture. Found under fingerprint ridges.

142

Free nerve ending

Unspecialized, afferent nerve ending, detecting pain, temperature, itch and tickle

143

Hair follicle

Innervated along length of shaft and wall of follicle

144

Vibrissae

Specialized hairs extremely sensitive to tactile sensation

145

Golgi tendon organ

A specialized structure within the tendons of skeletal muscle that senses muscle tension, provides stretch and movement information.

146

Muscle spindle

A specialized structure within skeletal muscles that senses muscle length; provides sensory information to neurons in the spinal cord via group Ia axons; also called stretch receptor.

147

Betz cell

Large pyramidal neurons located in the primary motor cortex that control voluntary movement. Send their axons down to the spinal cord via the corticospinal tract where in humans they synapse directly with anterior horn cells, which in turn synapse directly with their target muscles

148

Cerebellar foliae

Gyri of the cerebellum

149

Purkinje cell

Large GABAergic neuron with dense highly branched dendritic field which extend into molecular layer; in cerebellar hemisphere that projects an axon to the deep cerebellar nuclei (only output of cerebellar cortex). Primary influence on lateral motor system, particularly fine movements.

150

Granule cell

Populate granule cell layer (innermost layer of cerebellar cortex), receives input from mossy fibers and sends axons to outermost layer to form parallel fibers, which synapse on Purkinje dendrites (plasticity of these synapses is believed to be important for motor learning)

151

Parallel fibers

An axon of a cerebellar granule cell that innervates Purkinje cells; plasticity of these synapses is believed to be important for motor learning

152

Basket cell

Part of the molecular layer; makes inhibitory synapses on Purkinje cells from remote parallel fibers

153

Stellate cell

Part of the molecular layer; makes inhibitory synapses on Purkinje cells from remote parallel fibers

154

Golgi cell

Also part of granule cell layer; makes inhibitory synapses on granule cells

155

Climbing fiber

An axon of an inferior olive neuron (from medulla) that innervates a Purkinje cell dendrites of the cerebellum. ___ activity is an important trigger for LTD, a form of synaptic plasticity believed to be important for motor learning.

156

Mossy fiber

An axon of a pontine neuron (neocortex), vestibular nerve, reticular formation, or spinal cord that innervates (form excitatory synapses on) cerebellar granule cells.

157

Molecular layer

Cerebellum cortical layer that is the outer layer of folia

158

Purkinje layer

Cerebellum cortical layer that is the interface between the molecular and granular layers

159

Granular layer

Cerebellum cortical layer that is the interior neuronal layer

160

Limbic system

Comprised of deep brain structures (which include the hippocampus, amygdala, & hypothalamus) communicate widely with cortex and basal ganglia; probably involved in emotion, learning, and memory.

161

Amygdala

An almond-shaped nucleus in the anterior temporal lobe thought to be involved in emotion and certain types of learning and memory; Uses prefrontal and anterior temporal cortex to communicate to neocortex. Role in behavior initiation arousal of other parts of the brain

162

Hippocampus

A region of the cerebral cortex lying adjacent and medial to the olfactory cortex. In humans, the hippocampus is in the temporal lobe and may play a role in emotion, learning and memory. Uses cingulate and parahippocampal gyri to communicate with neocortex

163

Cingulate and parahippocampal gyri

Pathway from the thalamus to the hippocampus,
Responsible for focusing attention on emotionally significant events, and for associating memories to smells and to pain

164

Hypothalamus

Maintains homeostasis, temperature regulation

165

Pathways of the basal ganglia

Direct pathway:
Result: Cortex (e.g., premotor) stimulates muscle fibers via the corticospinal tract.

Indirect pathway
Decreased stimulation of the motor cortex by the thalamus and reduced muscle activity.

166

Both Basal Ganglia AND Limbic System are...

Complex set of highly interconnected structures communicating with many braihn regions to elcit and control complex behaviors.
Both deep medial brainb structures underlying the cortical lobes.