Major Divisions of the Brain Flashcards
Anatomical Dimensions
Neuraxis
The spine-to-brain path.
move from the nose to the tail of the animal (brain down to the spinal cord); decide what is anterior (rostral) and posterior (caudal)
Anterior
Towards the front of the brain.
Posterior
Towards the back of the brain.
Superior
Higher/above in the brain.
Inferior
Lower/below in the brain.
Rostral
Towards the front of the brain in humans and animals. Points up the spinal curvature in humans.
Dorsal
Towards the back. To humans, points to the top of our brain, but points sideways on our back. If a human had a fins like a fish, those would be visual indicators of the dorsal directions.
Caudal
Towards the “tail” (so for animals, towards the back of the brain, but for humans is both referring to towards the back of the brain and downwards on the axis of the brainstem/spinal cord).
Ventral
Towards the belly. In humans, points to the bottom of the brain and to the belly on the spinal axis.
Coronal Plane
Vertical plane that divides anterior and posterior sections of the brain.
Horizontal Plane
Divides the brain into superior (upper) and inferior (lower) sections.
Sagittal Plane
Vertical plane that divides the brain into left and right sections. Is called a midsagittal plane if it divides the brain directly in half.
Spinal Cord
Vertebrae → cervical→ thoracic → lumbar→ sacral→ coccygeal
Narrows/tapers when from cervical to coccygeal
The sacral region has fewer sensory neurons, and their information must travel upward to the brain. The cervical region is thicker due to more sensory input, and as motor outputs decrease down the spinal cord, the cord becomes thinner.
Spinal cord damage
loss of function related to segment of damage
Major divisions of the brain
Forebrain:
telencephalon
diencephalon
Midbrain:
mesencephalon
Hindbrain:
metencephalon
myelencephalon (or medulla)
What is the dorsal/ventral organization in the spinal cord?
The dorsal side carries sensory (afferent) information, while motor (efferent) information exits from the ventral side.
Myelencephalon
Intersection between the brain and the spinal cord- largely comprised of tracts; bundles of axons
Involuntary control of life-sustaining functions
Part of our brain that keeps our heart beating, diaphragm move even if we’re unconscious: swallowing reflex
Myelencephalon
How does spinal cord damage affect function?
Damage to the cervical region is the most severe because it blocks all afferent inputs and motor outputs, while damage to the thoracic region only affects inputs from lower segments like the lumbar and sacral regions, leaving cervical inputs intact.
Myelencephalon
Function of Reticular formation or the reticular activating system
consists of many nuclei that regulate basic functions. As you move higher in the system, it becomes essential for wakefulness, sleep, arousal, and attention.
Damage to this region can cause severe disruptions to life, such as difficulty staying awake, and may even be fatal.
Metencephalon
Contains many afferent and efferent pathways and also houses part of the reticular formation.
differentiates pons and cerebellum
Myelecephalon
Doctors are reluctant to perform surgery on the medulla
Small amount of damage; fatal or catastrophic results
Metencephalon
Role of the cerebellum, and what effects does damage to it have?
cerebellum makes up about 10% of brain volume and is primarily responsible for motor coordination rather than motor control.
not life-threatening but impairs the ability to make smooth, unconscious adjustments in movements, such as grabbing a cup, forcing individuals with damage to make these corrections consciously.
Metencephalon
What is the ventral side of the pons
A pale structure containing many myelinated axons (both afferent and efferent), continuing from the spinal cord and medulla.
Metencephalon
What happens if the ventral side of the pons is damaged?
Damage to the pons, such as a stroke, can result in a combination of numbness, lack of coordination, and disruptions to the sleep-wake cycle.
Mesencephalon (midbrain)
Divide midbrain by dorsal (roof or tectum)
Comprised of a roof (tectum) and a floor (tegmentum)
AKA the Boston Pizza Part of the Brain
Mesencephalon
Superior colliculi
vision with respect to eye movement
Mesencephalon
Inferior colliculi
auditory with respect
to head/body orientation
Mesencephalon
Tectum
Comprised of the inferior colliculus and the superior colliculus, which deal with auditory and visual processing
Mesencephalon
Damage to the mesencephalon
Stokes- trouble from automatic eye movement (orienting our eyes upward); Parinaud’s syndrome
Mesencephalon
Tegmentum
- Contains part of reticular formation
- More fibres
- Periacqueductal grey (main input is from the amygdala, motor control; ex: freezing when scared, flinching)
- Dopamine-producing regions
Metencephalon
Pons
large white-matter bulge,
continuing from spinal cord/medulla
* essential in sending information to your body
Damage to this region: combination of numbness/ lack of feeling in the body, lack of coordination, sleeping and waking state
Mesencephalon
Red nucleus
primarily involved in motor coordination, closely connected to the cerebellum, helping to coordinate fine motor actions (swinging of arms when walking)
if damaged: motor coordination problems
Mesencephalonss (Tegmentum)
Dopamine-producing regions
Substantia nigra and Ventral tegmental area (VTA)
Mesencephalon
Pattern of function
motor control, sensory processing, vision and hearing reflexes, and regulating consciousness and sleep-wake cycles.
Diencephalon
Comprised of two structures:
The thalamus and hypothalamus
Diencephalon
Thalamus
an egg-shaped structure in the middle of your brain. It’s known as a relay station of all incoming motor (movement) and sensory information — hearing, taste, sight and touch (but not smell)
inputs from sensory systems, cerebellum, basal ganglia
Diencephalon
Sensory info in the Thalamus
goes from thalamus to cortex but equal numbers come from cortex to thalamus= continuous loop
Diencephalon
Damage to the thalamus
people who have damage to thalamus disorder in conscious: look awake but they don’t really seem there
Diencephalon
Functions of the hypothalamus
sex, aggression, feeding, sleep, wake, more
Diencephalon
Corticothalamic loops
communication pathways between the cerebral cortex and the thalamus that play a critical role in processing and regulating sensory, motor, and cognitive information.
Two-Way Communication: These loops involve reciprocal connections, where the cortex sends signals to the thalamus (corticothalamic projections), and the thalamus sends information back to the cortex (thalamocortical projections).
Diencephalon
Hypothalamus
Key intersection with endocrine system via the pituitary gland (master gland)
Diencephalon
Damage to the hypothalamus
Regulatory role, interfere with sleeping, eating, sex
Damage in this region is hard to pin down
Diencephalon
Narcolepsy and the hypothalamus
Inability to stay awake; transition from awake to sleep so fast due to lost of specific neurons in the hypothalamus
Telencephalon
Largest in the human brain
by volume (not by total number of neurons)
Telencephalon
What are parts included in the telencephalon
Cortex, amygdala, hippocampus
Telencephalon
Damage
wide-ranging in its symptoms
seizure, stroke, alzheimer’s, cog. impairment
Telencephalon
Cerebral cortex
The cortex, neocortex
The largest and most prominent
feature of the human brain
Telencephalon
Why is the cortex highly convoluted
No special reason, just part of the brain that has the best ability to learn is in the cortex; we need more cortex so we fold it up and convolute it
Other mammals have smooth brains: The lissencephalic (smooth) cortices
Hemisphere
Corpus callosum
The corpus callosum is located in the central hemisphere and connected by cerebral commissures.
It connects the left and right hemisphere and allows for communication between them.
largest white matter structure in the brain
What is interesting about the damage in the convolutions
Some disorders affect the sulcus first before the gyrus
Hemisphere
Longitudinal fissure
Separates the ledt and right hemispheres
Hemisphere
Callosotomy
where some axons connecting the left and right hemispheres of the brain are cut to reduce excessive spontaneous activity. Patients report feeling no immediate effects after the procedure.
However, they may experience manual disagreement, where one hand acts independently of the other (e.g., one hand buttoning a shirt while the other unbuttons).
rare treatment for epilepsy
Hemisphere
Contralateral organization
Left hemisphere governs the right half of the word
Right hemisphere governs the left half of the world
Right hand is controlled by left and vice versa
Hemisphere
Left hemisphere dominance for language
Speaking, listening, language comprehension
right hemisphere has limited capacity or not so effective
Hemisphere
4 lobes in the cerebral cortex
frontal, parietal, occipital, temporal lobe
Hemisphere
Central fissure
separates frontal and parietal lobes
Hemisphere
Lateral fissure
separates temporal lobe from frontal/parietal
Deep in the letral fissure: the insula- older cortex underneath the cerebral cortex
Hemisphere
Limbic system
Amygdala (latin word for almond), HTh, mammillary body, hippocampus, fornix, cingulate cortex (related to sensation of pain, decision-making, tough decisions), septum, olfactory bulb
symptoms from damage can vary from region to region
Hemisphere
Basal Ganglia
Includes striatum (caudate + putamen) and globus pallidus (pale globe), sometimes others (e.g. subthalamic nucleus)
Critical in movement, skills, habits, decision making
Muscle memory
Learning skilled but not too thoughtful actions–playing piano, riding a bike
Somehow a part of drug addiction
Nucleus accumbens
subregion of striatum/caudate, sometimes called ventral striatum (opposite of dorsal)
Connected to drugs and addiction: important for motivation
Anatomy of the cortical layers
Layer 6- deepest
3,5,6 much thicker in motor cortex
4 is thick for
Sensory cortex vs motor cortex
In the sensory cortex, layers are thicker and packed with input-processing neurons (INPUT)
In the motor cortex, layers for sending signals are more prominent, reflecting their role in controlling movements. (OUTPUT)
Differences between
parts of the cortex
can be used to make maps
e.g. Brodmann areas
Line between motor and somatosensory (most anterior for parietal)
Central fissure
Precentral gyrus
Located in the frontal lobe, this is the motor cortex (Brodmann area 4), responsible for controlling voluntary movements.
Do we use only 10% of our brains?
NO.
Ex. drinking a glass of water
Make a decision that you want to drink water- prefrontal cortex
How to pick up a glass of water- Premotor areas; has the templates on how I should do it
Executed into motor commands- Motor cortex; Send axons to spinal cord (efferent signal)
regulates movement- basal ganglia
Brain stem- pons
Sensory info- weight of the glass etc- cerebellum
Looping to other areas to find motor coordination
Postcentral gyrus
Located in the parietal lobe, this is the somatosensory cortex (Brodmann areas 1-3), responsible for processing sensory information from the body.
Meninges
Three layers of membranes that protect the brain and spinal cord.
Pia mater, arachnoid mater, dura mater
4 total, including the skull
Layers that protect the brain and spinal cord
Skull -> Dura Mater -> Arachnoid mater -> Pia mater
Cerebrospinal fluid (CSF)
Fluid that flows in and around the hollow/empty spaces of the brain and spinal cord. The brain produces CSF for nutrients, to remove waste, etc. but also is like an “airbag” in case we bump our heads.
Flows down to central canal spinal cord- take a sample from spinal cord and withdraw the fluid and see what drug metabolize and see what’s happening at the CNS
Hydrocephalus
neurological disorder caused by an abnormal buildup of cerebrospinal fluid in the ventricles (cavities) deep within the brain
Passageways get blocked but ventricles keep producing CSF= puts pressure into the brain
Wants to drain but it can’t so it pushes against neurons
Ventricles will get larger and larger= hydrocephalus
If let untreated, consequences on cognition
Treatment for hydrocephalus
Insert an artificial tube (shunt) to drain from brain to abdomen
Cerebral blood flow
Flow from blood to brain is limited (supply) because there is only 4 veins (2 in front and 2 at back)
No redundancy, if 1 artery is blocked, that artery is gone; that’s why stroke is so detrimental
No reserves- energy brain consumes have no storage; drug overdose and no energy store= you can get brain damage
neurons= no oxygenated blood for 4 minutes= they start dying
Mesencephalon
periaqueductal gray
propagation and modulation of pain, sympathetic responses as well as the learning and action of defensive and aversive behaviors.
Medial
Towards the middle (of the brain).
Lateral
Towards the edge (of the brain).
