Neurophysiology 3 Flashcards
Describe the diencephalon
Retains its name from embryologic development.
It is the connection between the cerebrum and the rest of the nervous system, with one exception.
The rest of the brain, the spinal cord, and the PNS all send information to the cerebrum through the diencephalon.
Output from the cerebrum also passes through the diencephalon.
The single exception is the system associated witholfaction, which connects directly with the cerebrum
Lies deep beneath the cerebrum and constitutes the walls of the third ventricle.
Can be described as any region of the brain with “thalamus” in its name.
The two major regions are the thalamus itself and the hypothalamus.
Other structures include theepithalamus, which contains the pineal gland, and thesubthalamus, which includes the subthalamic nucleus that is part of the basal nuclei.
Describe the thalamus
A collection of nuclei that relay information between the cerebral cortex and the periphery, spinal cord, or brain stem.
All sensory information, except for the sense of smell, passes through the thalamus before processing by the cortex.
Axons from the peripheral sensory organs, or intermediate nuclei, synapse in the thalamus, and thalamic neurons project directly to the cerebrum.
It is a requisite synapse in any sensory pathway, except for olfaction.
It also processes that information.
The cerebrum also sends information down to the thalamus, which usually communicates motor commands.
This involves interactions with the cerebellum and other nuclei in the brain stem
How does the thalamus facilitate communication between the cerebrum and other nuclei?
An example is how the cerebrum interacts with the basal nuclei, which involves connections with the thalamus.
The primary output of the basal nuclei is to the thalamus, which relays that output to the cerebral cortex.
The cortex also sends information to the thalamus that will then influence the effects of the basal nuclei.
Describe the hypothalamus
Inferior and slightly anterior to the thalamus.
Is a collection of nuclei that are largely involved in regulating homeostasis.
Principal region in charge of the autonomic nervous system and the endocrine system through its regulation of the (anterior) pituitary gland.
Other parts are involved in memory and emotion as part of the limbic system.
Describe the brainstem
Collectively comprises the midbrain and hindbrain (composed of the pons and the medulla).
Located underneath the cerebrum and the cerebellum, connecting the brain to the spinal cord.
The major ascending and descending pathways between the spinal cord and brain, specifically the cerebrum, pass through the brain stem.
All information that goes from the brain to the body (or vice versa), must pass through the brain stem to reach its destination
It is responsible for regulating the heart and lungs, communications between the brain and the PNS, our sleep cycle, and coordinating reflexes.
The “reticular formation” is an area running throughout the brain stem.
The cranial nerves connect through the brain stem and provide the brain with the sensory input and motor output associated with the head and neck, including most of the special senses
What is the reticular formation?
The “reticular formation” is an area running throughout the brain stem.
A collection of nuclei that plays a vital role in managing our consciousness (e.g. sleep and alertness) and connecting with the various motor nervesto help us move our heads and faces, regulate our involuntary actions, and to help us chew, eat, breathe and see.
The reticular (from the Latin reticulum, meaning net) formationis a far-reaching network of neurons extending from the spinal cord to the thalamus, with connections to the medulla oblongata, midbrain (mesencephalon), pons, and diencephalon
Describe the midbrain
A small region between the thalamus and pons.
It is separated into thetectumandtegmentum, from the Latin words for roof and floor, respectively.
The cerebral aqueduct passes through the centre of the midbrain, such that these regions are the roof and floor of that canal.
Coordinates sensory representations of the visual, auditory, and somatosensory perceptual spaces.
It also plays a role in regulating our body temperature and motor movements
Describe the tectum aspect of the midbrain
The tectum is composed of four bumps known as the colliculi (singular = colliculus), which means “little hill” in Latin.
Theinferior colliculusis the inferior pair of these enlargements and is part of the auditory brain stem pathway.
Neurons of the inferior colliculus project to the thalamus, which then sends auditory information to the cerebrum for the conscious perception of sound.
Thesuperior colliculusis the superior pair and combines sensory information about visual space, auditory space, and somatosensory space.
Activity in the superior colliculus is related to orienting the eyes to a sound or touch stimulus.
Describe the tegmentum aspect of the midbrain
The tegmentum is continuous with the grey matter of the rest of the brain stem.
Throughout the midbrain, pons, and medulla, the tegmentum contains the nuclei that receive and send information through the cranial nerves, as well as regions that regulate important functions such as those of the cardiovascular and respiratory systems.
Describe the hindbrain
Made up of the pons and the medulla regulate several crucial functions, including the cardiovascular and respiratory systems
1. Pons: Latin word for “bridge.”
Is the main connection between the cerebellum and the brain stem.
It is visible on the anterior surface of the brain stem as the thick bundle of white matter attached to the cerebellum.
The bridge-like white matter is only the anterior surface of the pons; the grey matter beneath that is a continuation of the tegmentum from the midbrain.
Grey matter in the tegmentum region of the pons contains neurons receiving descending input from the forebrain that is sent to the cerebellum.
2. Located behind and partially underneath the cerebellum.
The medulla is the region known as the myelencephalon in the embryonic brain.
The “myel,” refers to the significant white matter found in this region—especially on its exterior, which is continuous with the white matter of the spinal cord.
The tegmentum of the midbrain and pons continues into the medulla and this grey matter is responsible for processing cranial nerve information.
What is the function of the pons
Responsible for assisting in motor functions, particularly for nerves in the face, ears, and eyes.
Also plays a role in regulating the intensity and frequency of breathing.
The reticular formation of the pons’ grey matter plays a vital role in dreaming and REM (deep) sleep
What is the function of the medulla?
Responsible for life-sustaining involuntary (autonomic) actions such as breathing, regulating the heartbeat and blood pressure, and reflexes such as sneezing, vomiting and coughing.
The reticular formation in the medulla’s grey matter assists with breathing and controlling the heart rate
Describe the cerebellum
Sits behind and beneath the cerebrum and above the brain stem.
‘Little brain’ in Latin.
The cerebellum is largely responsible for comparing information from the cerebrum with sensory feedback from the periphery through the spinal cord.
Thus, it is responsible for voluntary movements, co-ordination, balance, posture, muscle tone and cognitive functions.
Made up of: 2 layers, 2 hemispheres, 3 lobes and 4 nuclei
The vermis (Latin for ‘worm’) separates the hemispheres.
The lobes of the cerebellar cortex have no clear separation of function.
Each section of the cortex is best identified by the way they process information
In a loose parallel, both the cerebellar nuclei and corpus callosum are responsible for internal communication.
The c. callosum relays messages between the cerebral hemispheres and the cerebellar nuclei relays messages between the body and the cerebrum.
Distinguish between the layers of the cerebellum
Outer layer of grey matter called the cerebellar cortex.
Functions such as movement, motor learning, balance and posture happen here.
Inner layer of white matter called ‘arbor vitae’ (tree of life).
Contains cerebellar nuclei which relay information between the cerebral cortex and the PNS to assist in learning and cognitive functions, motor control, balance and co-ordination.
What are the functions of the cerebellar cortex?
