Week 3 - Neuroanatomy

Basal Forebrain

- Major source of acetylcholine in the brain for arousal and wakefulness - Composed of several structures that lie on the dorsal surface of the forebrain Contains the nucleus basalis ◦ Receives input from the hypothalamus and basal ganglia ◦ Sends axons that release acetylcholine to the cerebral cortex ◦ Important in arousal, wakefulness, and attention Receives input from the hypothalamus and basal ganglia and sends axons that release acetylcholine to widespread areas in the cerebral cortex (see Figure 3.16). The nucleus basalis is a key part of the brain's system for arousal, wakefulness, and attention, as we consider in the chapter on sleep. Patients with Parkinson's disease and Alzheimer's disease have impairments of attention and intellect because of inactivity or deterioration of their nucleus basalis.

Nucleus Basalis

- a forebrain structure - receives input from the hypothalamus and basal ganglia - sends axons to areas in the cerebral cortex - Important in arousal, wakefulness, and attention

olfactory bulb

- the first brain structure to pick up smell information from the nose... not contralateral - a brain structure located above the nasal cavity beneath the frontal lobes

Cranial Nerves

12 pairs of nerves that carry messages to and from the brain Allow the medulla to control sensations from the head, muscle movements in the head, and many parasympathetic outputs

The Pons

A brain structure that relays information from the cerebellum to the rest of the brain Latin: bridge Lies on each side of the medulla (ventral and anterior) Axons from each half of the brain cross to the opposite side of the spinal cord such that the left hemisphere controls the muscles of the right side of the body and the right hemisphere controls the left side = contralateralization

The limbic system

A doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres; Associated with motivation emotions, such as eating, drinking, sexual activity, anxiety, and aggression Consists of a number of other interlinked structures that form a border around the brainstem: - Includes the olfactory bulb, hypothalamus, hippocampus, amygdala, and cingulate gyrus of the cerebral cortex

Cerebellum

A large structure of the hindbrain that controls fine motor skills. Latin: little brain Structure located in the hindbrain with many deep folds ◦ Helps regulate motor movement, balance, and coordination ◦ Also important for shifting attention between auditory and visual stimuli Motor area... but does a lot more too...

Hippocampus

A neural center located in the limbic system that helps process explicit memories for storage. A large structure located between the thalamus and cerebral cortex ◦ Toward the posterior portion of the forebrain ◦ Critical for certain types of memory, especially memories for individual events. Encoding and retrival of experiences when it is relevant

Hypothalamus

A neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward. Near the base of the cortex Conveys messages to the pituitary gland to alter the release of hormones ◦ Associated with behaviors such as eating, drinking, sexual behavior, and other motivated behaviors with the thalamus, forms the "diencephalon" (with two others) Partly through nerves and partly by releasing hormones, the hypothalamus conveys messages to the pituitary gland, altering its release of hormones. Damage to any hypothalamic nucleus leads to abnormalities in motivated behaviors, such as feeding, drinking, temperature regulation, sexual behavior, fighting, or activity level. Because of these important behavioral effects, the small hypothalamus attracts much research attention.

Midbrain

A small part of the brain above the pons that integrates sensory information and relays it upward. Integrating information that comes from the periphery Tectum (Latin for "roof"): - top of the midbrain; responsible for alertness, and reflexives responses to auditory/visual stimuli -orients an organism in the environment Superior colliculus and inferior colliculus (Latin for "hill"): processes sensory information - located on each side of the tectum ◦ Tegmentum (Latin for "covering"): contains nuclei for cranial nerves and part of the reticular formation... pain, sleep, habituation to different stimuli, movement and arousal ◦ Substantia nigra (Latin for "black substance"): motor control, gives rise to the dopamine- containing pathway facilitating readiness for movement

Posterior

Brain: - back Spine - down Toward the rear end

Dorsal

Brain: - top Spine: - back Toward the back, away from the ventral (stomach) side. The top of the brain is considered dorsal because it has that position in four-legged animals.

The Forebrain

Cerebral Cortex (brain shell, outer portion) -Subcortical regions include the thalamus, hypothalamus - Limbic system =Olfactory bulb, hypothalamus, hippocampus, amygdala, cingulate gyrus of the cerebral cortex - pituitary gland, basal ganglia, - The most anterior and prominent part of the mammalian brain, with two cerebral hemispheres - Consists of the outer cortex and subcortical regions - Outer portion is known as the "cerebral cortex" - Each side receives sensory information and controls motor movement from the opposite (contralateral) side of the body - Info transferred across hemispheres via the corpus collusum - The cerebral cortex is the thin layer of the brain that covers the outer portion (1.5mm to 5mm) of the cerebrum. It is covered by the meninges and often referred to as gray matter. The cortex is gray because nerves in this area lack the insulation that makes most other parts of the brain appear to be white.

Brain Stem

Connects the brain to the spinal cord. Controls involuntary, life-sustaining activities such as breathing, heart rate, sleeping, and maintaining consciousness.

Hindbrain: Primitive

Consists of the... ◦ Medulla ◦ Pons ◦ Cerebellum - Located at the posterior portion of the brain - Hindbrain structures, the midbrain, and other central structures of the brain combine and make up the brain stem - Automatic, unconscious, involuntary... sneezing, coughing, vomiting, breathing, heartbeat, etc.

Ventricles

Four fluid-filled cavities within the brain's central canal containing cerebrospinal fluid Cerebrospinal fluid (CSF): a clear fluid found in the brain and spinal cord ◦ Provides "cushioning" for the brain ◦ Reservoir of hormones and nutrition for the brain and spinal cord

Medula

Located just above the spinal cord; like an enlarged extension of the spinal cord Responsible for vital reflexes such as breathing, heart rate, vomiting, salivation, coughing, and sneezing Primitive basic animal needs. Simple animals have the same structures and functions

medial/lateral

Medial: towards the midline Lateral: away from the midline

The Meninges

Membranes that surround the brain and spinal cord Contain pain receptors ◦ Meningitis= inflammation of the meninges —is painful ◦ Swollen blood vessels in the meninges are the cause of migraine headaches

Midbrain

Mesencephalon ("middle-brain") Tectum, tegmentum, superior colliculus, inferior colliculus, substantia nigra

The Spinal Cord

Part of the CNS found within the spinal column ◦ Communicates with the sense organs and muscles, except those of the head Bundle of neurons that extend down from the brain. Neurons in the periphery are attached to the spinal cord to send to the brain. it is a good way to relay info from other parts of the body. Efferent ventral roots afferent dorsal roots dorsal root ganglia

Forebrain

Prosencephalon ("forward-brain") Diencephalon ("between-brain") - thalamus, hypothalamus Telencephalon ("end-brain") - cerebral cortex, hippocampus, basal ganglia

Hindbrain

Rhombencephalon (literally/"parallelogram-brain") -Medulla, pons, cerebellum

Sympathetic Nervous System

STRESS A network of nerves that prepares the organs for rigorous activity: ◦ Increases heart rate, blood pressure, respiration, and so on. ("fight or flight" response) ◦ Composed of ganglia on the left and right of the spinal cord ◦ Mainly uses norepinephrine

Autonomic Nervous System

Sends and receives messages to regulate the automatic behaviors of the body (heart rate, blood pressure, respiration, digestion, etc.) Divided into two subsystems ◦ The sympathetic nervous system ◦ The parasympathetic nervous system

Nucleus

a cluster of neuron cell bodies within the CNS

sulcus

a fold or groove that separates one gyrus from another

fissue

a long, deep sulcus

Horizontal plane

a plane that shows brain structures as seen from above

Gyrus

a protuberance on the surface of the brain

lamina

a row or layer of cell bodies separated from other cell bodies by a layer of axons and dendrites

tract

a set of axons within the CNS, also known as a projection. If axons extend from cell bodies in structure A to synapses on B, we say fibers project from A to B

column

a set of cells perpendicular to the surface of the cortex, with similar properties

Basal Ganglia

a set of subcortical structures that directs intentional movements comprises the caudate nucleus, the putamen, and the globus pallidus Associated primarily with planning of motor movement ◦ Also important for attention, language planning, and other cognitive functions (e.g., emotions and memory) It has long been known that damage to the basal ganglia impairs movement, as in conditions such as Parkinson's disease and Huntington's disease. The basal ganglia integrate motivational and emotional behavior to increase the vigor of selected actions. However, the role of the basal ganglia extends beyond movement. They are critical for learned skills and habits, as well as other types of learning that develop gradually with extended experience. We return to the basal ganglia in more detail in the chapters on movement and memory.

inferior/superior

below, above

Ventral

brain: down spine: belly side, point to chest Toward the back, away from the ventral (stomach) side. The top of the brain is considered dorsal because it has that position in four-legged animals.

Anterior

brain: front spine: top, upwards Toward the front end

Ganglion

collection of nerve cell bodies in the peripheral nervous system

coronal plane

divides brain into front and back https://www.youtube.com/watch?

Sagital plane

divides the brain into left and right halves

Anatomical Directions in the Nervous system

good luck! totally do-able!

Spinal cord matter

gray matter inside, white matter outside Grey matter: located in the center of the spinal cord and is densely packed with cell bodies and dendrites White matter: composed mostly of myelinated axons that carries information from the gray matter to the brain or other areas of the spinal cord Each segment sends sensory information to the brain and receives motor commands

pituitary gland

hormone-producing gland found at the base of the hypothalamus The pituitary gland is an endocrine (hormone-producing) gland attached to the base of the hypothalamus (see Figure 3.10). In response to messages from the hypothalamus, the pituitary synthesizes hormones that the blood carries to organs throughout the body.

Divisions of different brains

humans need more forebrain mass

proximal/distal

nearer the attached end/farther from the point of attachment

the cranial nerves

no spinal chord in the head, so these nerves control.

parasympathetic nervous system

peaceful state Facilitates vegetative and nonemergency responses ◦ Decreases functions increased by the sympathetic nervous system ◦ Composed of long preganglion axons extending from the spinal cord and short postganglionic fibers that attach to the organs themselves ◦ Dominant during our relaxed states ◦ Mainly uses acetylcholine ◦ Inhibatory ◦ state of the body at rest, maintains basic functioning ◦ returns sympathetic nervous system to a state of rest

PNS

peripheral nervous system connects the brain and spinal cord to the rest of the body... organs, glands, muscles, skin... Consists of... Somatic nervous system: controls voluntary muscle movements & conveys sensory information to the CNS Autonomic nervous system: controls the heart, intestines, and other organs

ipsilateral/contralateral

same side/opposite side

Thalamus

the brain's sensory control center, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla the main source of input to the cerebral cortex the brain's sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla relay station from the sensory organs; main source of input to the cortex with the hypothalamus, forms the "diencephalon" (with two others) the thalamus is a pair of structures (left and right) in the center of the forebrain. The term derives from a Greek word meaning "anteroom," "inner chamber," or "bridal bed." It resembles two small avocados joined side by side, one in the left hemisphere and one in the right. Most sensory information goes first to the thalamus, which processes it and sends output to the cerebral cortex. An exception to this rule is olfactory information, which goes from the olfactory receptors to the olfactory bulbs and then directly to the cerebral cortex. Many nuclei of the thalamus receive their input from a sensory system, such as vision, and transmit information to a single area of the cerebral cortex, as in Figure 3.14. The cerebral cortex sends information back to the thalamus, prolonging and magnifying certain kinds of input and focusing attention on particular stimuli

Efferent ventral roots & Afferent Dorsal roots & Dorsal root ganglia

◦ Efferent ventral roots carry motor information away from the spinal cord ◦ Afferent dorsal roots carry sensory information towards the spinal cord ◦ The dorsal root ganglia cell bodies of sensory neurons located in clusters just outside the spinal cord