Neurobiology: Neuroanatomy - Test 2
A specialized cell in the retina that transduces light energy into changes in membrane potential.
Photoreceptor containing rhodopsin, concerned with low light vision. Connected to bipolar cells.
Photoreceptor in the retina used in daylight vision containing one of three photopigments to see colors. Connected to bipolar cells. Concentrated in the fovea.
Rods and cones (photoreceptors) are connected to these ___ cells that transmit graded signals to ganglion cells.
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.
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.
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.
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.
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.
A cell in the retina of the eye that
projects neurites laterally in the outer plexiform
layer. Makes predominantly lateral connections, transmits modulatory signals.
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)
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
Locally graded vs. action potential retinal cells
Locally graded: photoreceptors, horizontal and bipolar cells
Action potentials: Ganglion cells and amacrine cells.
Glial cells of the retina
Muller cells and astrocytes.
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.
The location on the retina where the optic nerve fibers leave the eye (blind spot).
The bundle of retinal ganglion cell axons that passes from the eye to the optic chiasm.
The structure in which the right and left optic nerves converge and partially cross to form the optic tracts.
Stable form of retinal bound to opsin (together, rhodopsin) when there is no light.
Primary visual cortex (V1)
Aka striate cortex, located at the pole of the occipital lobe
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.
In the dark (at rest), the photoreceptor is ____ by a continuous inward current flowing into the outer segment.
Light turns off the ongoing inward current, allowing the outward ____ current to ____ the cell.
Photopigment in rods
Glial cells of the retina, modulate synapse function, sequester neurotransmitters, ionic balance.
Lateral geniculate nucleus (LGN)
A thalamic nucleus that relays information from the retina to the primary visual cortex.
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.
A mass of neurons in the posterior thalamus that have widespread reciprocal connections with areas across the cerebral cortex.
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
The G-protein that couples rhodopsin to
the enzyme phosphodiesterase in rod photoreceptors
Visual pigment molecules consist of:
1) opsin (protein) and
2) retinal (chromophore)
Chemical group producing color in a compound.
Larger magnocellular retinal ganglion cell.
Smaller parvocellular retinal ganglion cell.
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
Three meningeal layers
(1) Dura mater, (2) arachnoid mater, and (3) pia mater.
Thick outer connective tissue layer.
Fluid filled cushion, highly vascularized.
Delicate inner layer contacting brain surface.
Large lateral fluid filled canals in the middle of the large hemispheres of the brain. Related to cerebral cortex and basal telencephalon.
Specialized secretory tissue in ventricles that makes cerebrospinal fluid.
Small centralized CSF canal that connects the lateral ventricles to the fourth ventricle. Related to thalamus & hypothalamus.
CN innervation controls sense of smell (Olfaction)
CN I (Olfactory)
CN nerves control visual perception and eye movements
CN II (Optic) ,III (Oculomotor), IV (Trochlear) and VI (Abducens)
Cranial nerve responsible for hearing and balance
CN VIII (Vestibulo-cochlear, as called Auditory/Vestibular)
Cranial nerves are responsible for the sense of taste
CN VII (Facial) and CN IX (Glossopharyngeal), anterior and posterior tongue, respectively
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)
One cranial nerve extends into the enteric system to innervate the gut and also controls swallowing
CN X (Vagus Nerve)
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
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
Axon conducting impulses toward the central nervous system, usually relays sensory information.
Axon conducting impulses outward from the central nervous system, usually relays motor signals.
Cranial nerve I
Olfactory nerve - sense of smell (sensory)
Cranial nerve II
Optic nerve - vision (sensory)
Cranial nerve III
Oculomotor nerve - eye movements; papillary constriction and accomodation; muscles of the eyelid (motor)
Cranial nerve IV
Trochlear nerve - eye movements (motor)
Cranial nerve V
Trigeminal nerve - somatic sensation of the face, mouth, cornea; muscles of mastication (both sensory and motor)
Cranial nerve VI
Abducens nerve - eye movements (motor)
Cranial nerve VII
Facial nerve - controls muscles of facial expression; taste from anterior tongue; lacrimal (tear) and salivary glands (both sensory and motor)
Cranial nerve VIII
Auditory/Vestibular nerve - hearing; sense of balance (sensory)
Cranial nerve IX
Glossopharyngeal nerve - sensation from pharynx; taste from posterior tongue; carotid baroreceptors (both sensory and motor)
Cranial nerve X
Vagus nerve - autonomic functions of the gut; sensation from pharynx; muscles of vocal cords; swallowing (both sensory and motor)
Cranial nerve XI
Accessory nerve - shoulder and neck muscles (motor)
Cranial nerve XII
Hypoglossal nerve - movements of tongue (motor)
Cerebrospinal fluid (CSF)
Protective cushion and circulates metabolytes; clears toxins for venous drainage; maintains ionic & pH balance
Filled with salty, clear liquid; squishy cushion between supportive membranes inside of skull (dura) and the surface of the brain (pia)
CSF path (flow)
Cerebrum -> brain stem core -> subarachnoid space -> special structures called arachnoid villi absorb CSF
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.
Related to tectum and midbrain tegmentum.
Blood supply to spinal cord (2)
Vertebral arteries & medullary arteries
Arise from segmental branches of aorta; form anterior & posterior spinal arteries; lesions?
Blood supply to brain (2)
Internal carotids & vertebral arteries
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
The sulcus (groove) in the cerebrum that divides the frontal lobe from the parietal lobe (between precentral and postcentral gyri).
The largest part of the forebrain; also called telencephalon. Divided into the frontal, parietal, occipital and temporal lobes.
Lies immediately anterior to the central sulcus (posterior frontal); its neurons control voluntary movement
Lies immediately posterior to the central sulcus (anterior parietal); its neurons control somatic sensation (touch)
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
Primary somatosensory cortex
Brodmann’s area 3b located in the postcentral gyrus; also called S1.
The great cerebral commissure, consisting of axons connecting the cortex of the two cerebral hemispheres.
A region of the brain stem derived from the prosencephalon (forebrain). Diencephalic structures include the epithalamus, thalamus and hypothalamus
The ventral part of the diencephalon, involved in the control of the autonomic nervous system and the pituitary gland.
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
Controlled by epithalamus; releases melatonin as part of the retinohypothalamic tract that drives circadian rhythms
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.
Makes up 80% of the diencephalon, highly
interconnected with the cerebral neocortex.
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
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.
Caudate + Putamen
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.
Egg shaped structure at the anterior end of the striatum, adjacent to the thalamus. Part of basal ganglia, involved in motor control.
Putamen + 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.
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.
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.
The region of the brain derived from the
caudal primary embryonic brain vesicle; also called
rhombencephalon. Structures include the
cerebellum, pons, and medulla.
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.
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).
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.
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.
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.
The part of the rostral hindbrain that lies ventral to the cerebellum and the fourth ventricle. Switchboard connecting cerebellum to cerebral cortex.
The part of the hindbrain caudal to the pons and cerebellum. Contains the vagus nerve.
The part of the central nervous system in
the vertebral column
The ventral region of the spinal cord containing neuronal cell bodies of motor neurons that affect the axial muscles.
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.
Consists mostly of glial cells and myelinated axons that transmit signals from brain to body, superficially located in spinal cord
Contains neural cell bodies; in horn areas of spinal cord.
A white matter tract on the dorsal side of the spinal cord, carrying touch and proprioceptive axons to the brain stem.
The tract that originates in the neocortex and terminates in the spinal cord; involved in the control of voluntary movement.
A tract originating in the red nucleus and terminating in the spinal cord; involved in the control of movement.
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.
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.
A membrane at the internal end of the auditory canal that moves in response to variations in air pressure; also called eardrum.
Malleus, incus, stapes
An ossicle in the middle ear attached to the
tympanic membrane; shaped somewhat like a hammer.
An ossicle in the middle ear whose shape somewhat
resembles an anvil.
An ossicle in the middle ear attached to the oval window that somewhat resembles a stirrup
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.
A spiral bony structure in the inner ear that
contains the hair cells that transduce sound.
Organ of Corti
An auditory receptor organ that contains hair cells, rods of Corti, and supporting cells
Inner hair cell
An afferent auditory cell located in the organ of Corti; the primary transducer of sound into an electrochemical signal
Outer hair cell
An auditory receptor (efferent) cell located in the organ of Corti in the inner ear.
A membrane in the cochlea in the inner ear along which the hair cells are located.
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.
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
A component of the vestibular labyrinth in the inner ear that transduces head rotation.
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)
Anterior semicircular canal
Movement of the fluid in this canal detects rotation of the head around a rostral-caudal (up-down) axis.
Posterior semicircular canal
Movement of the fluid in this canal detects rotations of the head in the sagittal plane (forward-back)
The utricle or the saccule, organs of the vestibular labyrinth in the inner ear that transduce head tilt and acceleration
One of the otoliths; sensitive to vertical acceleration
One of the otoliths; sensitive to horizontal acceleration
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
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
Primary auditory cortex (A1)
Brodmann’s area 41, on the superior surface of the temporal lobe
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.
A mechanoreceptor of the deep skin, selective for high-frequency vibrations. Pressure sensor in skin (large receptive field)
A slowly adapting mechanoreceptor of shallow skin, sensing pressure or compression
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.
A slowly adapting mechanoreceptor that senses pressure and texture. Found under fingerprint ridges.
Free nerve ending
Unspecialized, afferent nerve ending, detecting pain, temperature, itch and tickle
Innervated along length of shaft and wall of follicle
Specialized hairs extremely sensitive to tactile sensation
Golgi tendon organ
A specialized structure within the tendons of skeletal muscle that senses muscle tension, provides stretch and movement information.
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.
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
Gyri of the cerebellum
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.
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)
An axon of a cerebellar granule cell that innervates Purkinje cells; plasticity of these synapses is believed to be important for motor learning
Part of the molecular layer; makes inhibitory synapses on Purkinje cells from remote parallel fibers
Part of the molecular layer; makes inhibitory synapses on Purkinje cells from remote parallel fibers
Also part of granule cell layer; makes inhibitory synapses on granule cells
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.
An axon of a pontine neuron (neocortex), vestibular nerve, reticular formation, or spinal cord that innervates (form excitatory synapses on) cerebellar granule cells.
Cerebellum cortical layer that is the outer layer of folia
Cerebellum cortical layer that is the interface between the molecular and granular layers
Cerebellum cortical layer that is the interior neuronal layer
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.
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
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
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
Maintains homeostasis, temperature regulation
Pathways of the basal ganglia
Result: Cortex (e.g., premotor) stimulates muscle fibers via the corticospinal tract.
Decreased stimulation of the motor cortex by the thalamus and reduced muscle activity.
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.