Overview of the Nervous System II

diencephalon

• Thalamus

• Hypothalamus

• Optic nerve & retina

Thalamus

structure located under lateral ventricle and nicknamed the relay center

• somatosensory, visual, and auditory processing & motor control

• conveys sensory information to the cortex

• modulates attention and consciousness

• regulates sleep and wakefulness

• subnuclei have distinct features and functions including special senses

Hypothalamus

structure located under the thalamus on a coronal plane, surrounding the 3rd ventricle

• regulates homeostasis via connections with autonomic, endocrine and motivational systems

• regulates temperature, hunger, thirst, circadian rhythms, reproduction, and growth via connections with the pituitary

• HPA = ___-pituitary axis

Brainstem

Group of structures made of the midbrain, the pons, and the medulla

• control attention, consciousness, parasympathetic reflexes (BP and breathing), monoamine nuclei regulate arousal, motor, sensory, and special senses of the head and neck

• includes cranial nerve nuclei and associated fiber tracts

monoamine nuclei

monoamine neurons in the brainstem that have widespread projections into the cortex that regulate diverse functions

• Locus Coeruleus (norepinephrine)

• ventral tegmental are (VTA) (dopamine)

• substantia nigra (SN) (dopamine)

• dorsal Raphe nucleus (DRN) (serotonin)

Locus Coeruleus

monoamine circuit releasing norepinephrine

VTA and substantia nigra

monoamine circuits releasing dopamine

dorsal Raphe nuclei

monoamine circuit releasing serotonin

Mesencephalon

Division of brain made of the midbrain

NAME: ___

STRUCTURES: tectum, tegmentum, fibers/cerebral peduncles

LOCATION: under thalamus on sagittal plane

tectum

top part of midbrain/mesencephalon

NAME: ___

STRUCTURES: superior colliculus & inferior colliculus

FUNCTIONS: reflex control of visual information and auditory information respectively for each structure.

Tegmentum

body of midbrain under cerebral aqueduct

NAME: __

STRUCTURES: substantia nigra & periaqueductal gray (PAG)

FUNCTIONS: dopamine motor functions & pain regulation respectively

dopamine oxidation

The dark color in the substantia nigra in the tegmentum of the midbrain is due to ___

cerebral peduncles

bottom “lobes” of the midbrain

projections from the cortex, SPC, and cerebellum, including the corticospinal tract

metencephalon

division made of the cerebellum & pons

NAME: ___

STRCUTURES: cerebellum & pons

FUNCTIONS: integration of voluntary movement, posture, balance, coordination

cerebellum

part of metencephalon

cortex composed of 3 layers: granular, molecular, and Purkinje cells. Also have deep nuclei acting as the major OUTPUTS, also have cerebral peduncles connecting to both afferent and efferent fiber tracts

• integration of voluntary movement

• posture and balance control

• coordination

Pons

part of metencephalon

looks striped like thin stacked layers

• nuclei including reticular formation and locus coeruleus (norepinephrine)

• fiber tracts with connections to cortex and cerebellum

myelencephalon

division made of the medulla

NAME: ___

STRUCTURES: medulla, cranial nerve nuclei (top of slice) and pyramidal tracts

FUNCTIONS: control of vegetative functions (heart rate and breathing rate)

spinal cord

has levels: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral

made out of gray matter (cells) and white matter (tracts)

ascending and descending tracts have specific localizations within the white matter

• conveys sensory and motor information between the brain and body

• control reflex arcs

somatic innervation

• skeletal muscles

• voluntary movement

• 1 neuron system

visceral innervation

visceral and cardiac muscles, vasculature, glands

involuntary movement

involves autonomic ganglion in both sympathetic and parasympathetic nervous system

2 neurons system (pre- & postganglionic neurons)

parasympathetic division

• rest, digest, feed, and breed

• cranial and sacral SPC nerves

• ganglia are near or in the wall of target organs

sympathetic division

• fight or flight

• thoracic and lumbar SPC nerves

• ganglia are at some distance/farther from target organs

enteric division

division of autonomic nervous system that interacts with the gut and has both sympathetic and parasympathetic innervations

neural circuits

• visual pathways

• pain pathways

• dopamine pathway

• mesolimbic pathway

multiple ___ interact to regulate functions like reward

spinoparabrachial tract

afferent pain pathway from superior dorsal horn in SPC and feeds brain area concerns with affect

spinothalamic tract

afferent pain pathway from SPC dorsal horn feeding brain areas concerned with both affect and discrimination

nigrostriatal pathway

dopamine neurons in substantia nigra project to caudate & putamen aka dorsal striatum

• motor functions and habits

degeneration of neurons in this pathway leads to Parkinson’s disease

mesolimbic pathway

dopamine neurons in ventral tegmental area (VTA) project to nucleus accumbens (NAc) aka ventral striatum

• role in reward