Chapter 2: What is the Nervous System's Functional Anatomy (P1) Flashcards
Describe the overview of the brain function and structure.
- brain’s primary function = produce behavior
**everything our body does
- receives info about this world
- NS sensory organs gather info about the world - integrates info to construct subjective experience of reality (perception)
- sensory organs gather info in world / convert info into biological activity that constructs perceptions
EX: what we hear, smell, taste, and feel
**subjective reality = essential to carrying out any complex behavior
EX: a phone ringing
- our brain directs our body to reach for it as the NS responds to vibrating air molecules –> by producing subjective experience of a ringtone
- we perceive this stimulus as sound/react to it as if it actually exists –> however, the ringtone = fabrication of the brain
- produce commands = control movement of muscles
- compared to a computer
**cognitive psychology - receives info from the world to our receptors (sensory information)
EX: vision, audition, olfaction, gustation, somatosensation
EX: we know we have socks on our feet however, we ignore the feeling that we have socks on
Evolution
- created adaptations
- equipped each species w view of the world that helped it survive
**additional notes
- these are behaviors we have: social groups specific to us
- specific world view –> different organisms have different perspectives
EX: geese see UV light
- they perceive things differently –> can see things other species can’t (like humans) = gives them a different reality
What is the research focus agenesis of the cerebellum?
Agenesis
= failure of brain regions to develop
- offers researchers opportunity to study brain organization and function
: in rare cases –> a complete structure is absent **however, part of the brain appears normal
: brain plasticity in response to early perturbations = allows for compensation as regions of the cerebral cortex begin to function more efficiently
EX: a man who has cerebellar agenesis
**the cerebellum failed to develop
- although he lacks 80% of his neurons –> the young man’s behavioral capacities = remarkable (however, his behavior is not typical)
- he has distinctive speaking pattern, awkward gait/difficulties w balance/difficulties in planning/abstract thinking
- although ppl w cerebellar agenesis have more slowly developing language/ motor functions
= show improvement over time/ able to compensate for many of their symptoms
**some of the symptoms of autism early in life
- although heterogenous set of symptoms appear – neuropsychological assessment show deficits reminiscent of people w damage to the frontal/parietal cortical regions of the brain
: slower developing language/motor functions = are compensated/improvement are often seen over time
What are plastic patterns of neural organization?
- the brain = plastic
- neural tissue has capacity to adapt to world by constantly changing its functions are organized
EX: a person blind from birth has enhanced auditory capacities bc some of the brain’s visual regions –> been co-opted for hearing
- brain is also plastic in sense that connections among neurons (in given functional system) = constantly changing in response to experience
- Neuroplasticity
- the NS’ fundamental potential to physically/chemically modify itself in response to changing environment/compensate for age-related changes/injury
EX: can show the ability of IQ
- if you don’t have the range (i.e., 130) and you have an IQ of 115 –> your brain is doing all it can to make you as smart as it can
**but nutrition can play a big role in IQ
–> cell death /other neurons or cells will have to do the work to compensate
- Phenotypic Plasticity
- individual’s capacity to develop range of phenotypes
**these are the characteristics we can see/measure
EX: our skin responds to UV rays by incorporating more melanin = causing it to darken as a protective measure
: individual’s genotype (genetic makeup) interacts w the environment to elicit a specific phenotype
- Influences of epigenetic factors
- don’t change genes but influence how genes are inherited from parents express specific traits
Figure 2-1 (the mice)
- appear very different: one is fat, the other one is thin
- one has dark fur, the other is light-colored
**however, these mice are clones = genetically identical
- appear different bc their mothers were fed different diets while pregnant
- diet supplements added chemical markers/epigenetic tags on specific genes
: tags determine if the gene is available to influence cells (including neurons) –> leading to differences in body structure/eating behavior
**additional notes
- chemical marker that tells the genes when/not to express themselves = can be passed onto the generation
- will tell the genome whether or not to display that characteristic or not
**if a famine were to occur, it can have long lasting effects and have a marker that doesn’t allow you to be your best potential –> early life experiences can have lasting effect on you = physically & emotionally
What is the functional organization of the Nervous system: Parsing in the nervous system?
central nervous system
- the brain & spinal cord
Peripheral nervous system
- Nerve fibers radiating out beyond the brain and spinal
- and all neurons outside the brain and spinal cord
Figure 2-2A
- charts anatomical organization
- PNS nerves carry sensory info into the CNS & carry motor instructions from the CNS to the body’s muscles and tissues
**including performance such as functions as blood circulation and digestion
A) Anatomical organization
NS
1. CNS
- brain and spinal cord
- PNS
- Somatic NS
- Autonomic NS
- Enteric NS
B) Functional Organization
NS
- CNS
: mediates behavior (brain and spinal cord)
- SNS
: transmits sensation, produces movement (cranial nerves & spinal nerves) - ANS
: balances internal functions (sympathetic division: arousing & Parasympathetic division (calming) ) - Enteric nervous system
: controls the gut
**In functional organization
- focus = how parts of the system work together
- neurons in somatic division of PNS –> connect through cranial/spinal nerves to receptors on the body’s surface/on its muscles
- somatic neurons gather sensory information for the CNS / convey info from the CNS to move muscles of the:
- head
- neck
- face
- trunk
- limbs
**the autonomic division of the PNS
- enables the CNS to govern workings of our body’s internal organs
: our heartbeat, urination, pupillary response, diaphragm movements –> that inflate/deflate our lungs
: rest/digest response through parasympathetic (calming) nerves / its opposite (fight or flight response)
–> or vigorous activity through the sympathetic (arousing) nerves
**enteric nervous system
- often considered part of the nervous system –> controls digestion and stomach contractions
- can communicate w the CNS via the ANS –> mostly operates autonomously
Define the Neural information flow.
- directional flow of neural information
- afferent information
- comes into the CNS (incoming information)
**sensory incoming pathways = afferent - Efferent information
- leaves the CNS (outgoing information)
**Motor outgoing pathways are = efferent
EX: when you step on a tack –> afferent sensory signals transmitted from the body into the brain
–> then perceived as pain
–> efferent signals from the brain cause a motor response = lifting your foot
What is the Nomenclature for Brain Structure?
- Nomenclature for brains structure
: historically = lack coherence
–> multiple names; interchangeable terms; various languages, numbers, and letters
–> many brain structures have several names/terms often used interchangeably
**this nomenclature arose bc research on the brain/behavior spans several centuries/includes scientists of many nationalities/languages
What is the Nomenclature for brain structure? What are the description of brain structure locations?
- brain-body orientation
- frame of reference is human face - Spatial orientation
- frame of reference = other body parts/body orientation - anatomical orientation
- frame of reference = direction of a cut/section –> through human brain from viewer perspectives
Describe the brain-body orientation.
Brain-body orientation
- shows brain structure location from –> the frame of reference of the human face
medial
- structures towards the midline
Lateral
- located towards the side
Anterior
- what we consider the front /anterior to the face
Posterior
- opposite to anterior
- the back of the head
Dorsal
- structures atop the brain
- a structure within the brain
**above the midbrain considered = superior
**below midbrain = posterior
Ventral
- structures towards the bottom of the brain
- one of its parts are ventral
**direction of the abdomen
**above midbrain = inferior
**below midbrain = anterior
Additional notes
- named one brain region the gyrus fornicatus
–> thought that it had a role in sexual function **however, most of this region has nothing to do with sexual activity
Describe Spatial Orientation.
- shows the brain structure location in association to other body parts and body orientation
Rostral
- in direction of the nose
**above the midbrain = anterior
**below the midbrain = superior
EX: A beak of the bird
Caudal
- in direction of the tail
**above the midbrain = posterior
–> posterior & caudal **both mean “tail”
**below the midbrain = inferior
Dorsal
= back
Ventral
= stomach parts of the brain
–> located near those body parts
Superior
- above (towards the head)
Inferior
- below (towards the feet)
**superior & inferior = used to refer to structures located (dorsally/ventrally)
–> have only to do w location - not importance
EX 2: Dogs
- animals’ brains are similar but the spinal cord orientation can differ
–> this is bc many animals stand on all 4 legs
(compared w head orientation of 4-legged animal)
**dorsal/ventral - take 90* turn counter clockwise when describing the human or the bird brain
Anatomic Orientation
- shows the direction of the cut/section –> through the human brain (part A) from the perspective of a viewer (part B)
**look at diagram
- Plane of section (A) = coronal section
- cut in a vertical plane (from the crown of the head down)
- shows a **frontal view of the brain’s internal structures
- Plane of section = Horizontal section
- the view or cut falls along the horizon
–> usually viewed looking down on the brain from above
**dorsal view
–> a way that MRI is viewed of looking at a brain (this is the axial section)
- Plane of section = Sagittal section
- cut lengthways from front to back
- viewed from the side
**imagine the brain splot by an arrow
- midsagittal plane divides the brain into symmetrical halves
**medial view
what is cerebral protection?
- the brain’s surface features = protection covering
: triple-layered covering (the meninges) –> encases the brain & spinal cord / cerebrospinal fluid (CSF) = cushions them
**Meninges = protects the brain and spinal cord
EX: a traumatic brain injury
- when you hit your head (there are vessels) that might rupture (can be concerning)
- can create a mass (which creates blood in the brain)
–> our skull isn’t expandable so the pressure in the skull increases (which puts pressure into the brain) that can create mechanical trauma to the brain
**when someone hits their head - you want to make sure they don’t go unconscious
–> this can press on the brain stem (which can be dangerous)
Spinal fluid (csf)
- Also protects the brain
–> (in terms of cushion) in the brain so we don’t hit our skull
- creates boyance (so the brain isn’t so heavy)
- takes away wastes and puts it into the lymphatic system
**between the pia mater & brain
- the outer dura mater
- Latin = “Hard Mother”
- tough durable layer of fibrous tissue (attached to skull/encloses the brain & spinal cord (in loose sac)
**like leather
- in the middle = arachnoid layer
- greek = spider’s web
- ultrathin sheet of delicate connective tissue (follows the brain’s contours)
**on top of the pia mater
–> important for cooling the brain and taking in oxygen
- the inner layer –> pia mater
- Latin = “soft mother”
- moderately tough membrane of connective tissue –> clings to the brain’s surface
What is the Clinical Focus of Meningitis and Encephalitis?
Meningitis
- harmful viruses/microorganisms (such as bacteria, fungi, and protozoa) invade/multiply in the layers of the meninges
**specifically in the (pia mater & arachnoid layer) and CSF flowing between them
- “inflammation of the meninges”
: In response to the infection - body produces WBC designed to attack/consume these invaders
- inflammatory response: increases pressure within the cranium
–> which affects the functioning of the brain - unrelieved cranial pressure can lead to delirium
**if infection progresses to: drowsiness, stupor, coma, and even death
–> is contagious - symptoms
-> severe headaches/stiff necks (cervical rigidity)
treatment
- antibiotics when causation = microorganisms
- antiviral drugs for viral infections
**can have long-term consequences
Encephalitis
- infection of the brain (inflammation of the brain)
- caused by a number of different invading viruses or microorganisms
EX: COVID-19, SARS - different forms of encephalitis attacks one cerebral hemisphere in children
- gains access through olfactory pathway, cranial nerves, WBC
–> enters neurons and glial cells in cardiac & respiratory brainstem centers - Only radical treatments are effective
1. hemispherectomy
–> surgically remove entire affected hemisphere
2. vaccinations
What is Cerebral Geography?
cerebral cortex
- 2 nearly symmetrical left/right hemispheres
**mostly symmetrical (but has differences)
- outer forebrain consists of folded/layered tissue
**covers most of the brain - brain folds demarcate its functional cortical zones
**the brains fold are not random - cerebral cortex
: the brain’s - thin, outer “bark” layer
Each hemisphere = divided into 4 lobes:
1. frontal (executive function)
EX: decision making & voluntary movement
**above the thumbnail –> our fingers correspond to location of the frontal lobe
- parietal (sensory integration)
- top of the skull
**represented by your knuckles (behind the frontal lobe)
:Functions
- directing our movements toward a goal/ to perform a task (EX: grasping an object)
- temporal (auditory, taste, smell, memory)
- lies at the side of brain **below parietal lobe (same place as upraised fist
: functions
- hearing, languages, musical abilities, facial recognition/emotional processing
- occipital (visual)
- located at the back of the hemisphere (near your wrist)
**where visual scene processing begins
What are the bumps & cracks in the brain called?
Gyri
- the bumps in the brain’s folded surface
sulci
- the cracks in the brain `
Define examining the Human brain.
Figure 2-6A
- shows the dorsal view
- the brain’s wrinkled left/right hemisphere = constitute the cerebrum
**cerebrum = major forebrain structure / the most recently expanded feature of mammalian CNS
central sulcus
- this is what differentiates the lobes
Longitudinal fissure
- this is what divides the lobes
Visible from the dorsal view
1. the frontal lobe
2. parietal lobe
3. occipital lobe
- longitudinal fissure
- central sulcus
Figure 2-6B
- shows a ventral view of the brain
- the brain stem is visible from the opposite ventral view
- includes the wrinkly hemispheres of the smaller cerebellum
**also known as “little brain” in Latin
Visible from the Ventral view
1. Frontal lobe
2. Temporal lobe
3. occipital lobe
- brainstem: connects brain to spinal cord
- olfactory bulbs: rounded mass of tissue – contains several nerve cells involved in sense of smell
- cranial nerves
1. olfactory nerve (I)
2. optic nerve (II)
3. oculomotor nerve (III)
**MANY MORE but not cited in these flashcards
Figure 2-6C
- shows a Lateral view of the brain
- both cerebrum/brainstem = visible in lateral & medial views (figure 2-6D)
- shows the lateral fissures along the sides of the brain
** the very deep sulci are called = fissures
–> and along w the central sulcus - this runs from the lateral fissures across the top of the cerebrum
Visible from the lateral view
1. frontal lobe
2. parietal lobe
3. temporal lobe
4. occipital lobe
- central sulcus
- lateral fissure
Figure 2-6B
- shows a wrinkled cerebrum that’s ventral to the cerebellum (smooth, whitish structure)
–> w tubelike protrusions attached (brainstem)
function of brainstem
- responsible for critical functions of life such as:
1. heart rate
2. breathing
3. sleeping/eating
tubelike protrusions
- cranial nerves that run to/from brain as part of the SNS
Define the surface features of the brain
- Cerebrum
- everything that’s not in the cerebellum
- largest part of the brain
- divided into 2 hemispheres = cerebral hemispheres
function
- controls muscle functions, speech, thought, emotions, reading/writing, and learning
- Cerebellum
- known as “little brain”
function
- role in motor movement regulation & balance control
- coordinates gait/maintains posture
- controls muscle tone/voluntary muscle activity **however, unable to initiate muscle contraction
- located near the brainstem
- Gyrus
– also known as gyri
- bumps in the brain - Sulcus
- also known as sulci
- these are the cracks in the brain - fissure
- deep sulci are called fissures
**there are different types of fissures in the brain - longitudinal fissure
- lateral fissure
- brainstem
- area responsible for critical functions of life
What is cerebral circulation?
- brain’s surface = covered w blood vessels
: arteries feed blood to brain/send it back through veins to our kidneys /lungs for cleaning and oxygenation
- each of 3 major arteries that feeds blood to cerebral hemispheres –> branches extensively to supply regions in the brain (shaded in pink in diagram)
: 3 major arteries: anterior, middle, posterior cerebral arteries
- stroke occurs w blockage or break in cerebral artery
: this is due to the brain being highly sensitive to blood loss - a blockage/break in a cerebral artery = likely to lead to the death of the affected region = stroke
Stroke
- sudden appearance of neurological symptoms –> result of severely reduced blood flow
- due to the 3 cerebral arteries supplying different parts of the brain –> strokes can disrupt different brain functions **depending on the artery affected
- Anterior Cerebral artery
**dorsal view
- can see it along the longitudinal fissure - affects the right and left hemispheres
**lateral view
- can see the affected artery along the top of the brain
- Middle cerebral artery
**lateral view
- affects the side of the brain
**medial view
- affects the bottom left side of the brain
- Posterior Cerebral artery
**ventral view
- affects the bottom right side of the brain
left hemisphere
- affects sensation
right hemisphere
- movement on the right
What is the Clinical Focus of a stroke?
- worldwide: stroke = 2nd leading cause of death
- 8/10 stroke victims survive
- consequences of stroke = significant for most/often diminish quality of life
- major categories of stroke (ischemic & hemorrhagic) –> differ in cause, treatment, and consequences:
- Tissue plasminogen activator (t-PA)
- Neuroimaging
- Brain stimulation
Acute symptoms of a stroke:
- facial droop
- motor weakness in limbs
- visual disturbance
- speech difficulties
- sudden onset of severe headache
Ischemic stroke
- blood vessel = blocked by blood clot (known as a thrombus) OR some other obstructive material such as:
- fats, clumps of bacteria, or cancer called = embolus
Ischemia
- refers to failure to deliver sufficient oxygen, glucose/ other nutrients for cellular metabolism
- also inadequate removal of metabolic waste (such as carbon dioxide)
***Additional notes
- the longer we live –> the more likely we are to die of a stroke
- most stroke survivors have some residual motor sensory/cognitive deficit
- brain’s connections are crosses, therefore, even though a stroke happened in the left hemisphere **the right side of the brain will also be affected
what are treatments of a stroke? What is a tissue plasminogen activator (t-PA)?
- ischemic stroke can be treated w t-PA
- our body produces t-PA as natural prevention for excessive clotting
- dosage of t-PA given within 3-5 hours of onset ischemic symptoms = will boost a patient’s t-PA levels by 1000 times above normal
: thus, facilitate breaking up clots/allow normal blood flow to return to affected region
- those who don’t see effectiveness of t-PA = their outcomes are worsened
**no treatment for hemorrhagic stroke
–> using t-PA on a patient who has hemorrhagic stroke would kill them
What are treatments for strokes? What is neuroimaging?
- research shows that it’s possible to remove clots from cerebral vessels mechanically
- achieved by using advanced radiographic imaging techniques to guide long, thin catheter tube w springlike mechanisms on the end
–> inserted into the femoral artery near groin
–> the tube is threaded through the body into the brain/right to the clot
**springlike mechanism can either grab the clot or bust it up
What are treatments for a stroke? What are brain stimulations?
- deep brain stimulation that activates/inhibits the brain with electricity
What are the brain’s internal features?
Figure 2-8B
- the brain’s inner features can be seen by slicing it parallel to the front of the body
–> downward through the middle in a coronal section
- the brain’s interior is not homogenous (dark grayish/lighter regions) of tissue are visible
**represent different brain components
macroscopic inspection: regions and hemispheres
- gray matter
- largely composed of cell bodies/capillary blood vessels
- neurons collect/modify information before sending it along
- white matter
- mostly nerve fibers covered by myelin sheaths (have a high fat content)
- these fibers produce the white appearance
- white matter fibers form long-distance connections between/among some of the brain’s neurons
- can see if there’s something wrong or missing development in white matter
EX: checking for behavioral things such as: memory or math abilities
- corpus callosum
- contains 200mill nerve fibers that join the 2 hemispheres/allow them to communicate
- bundle of axons
What are the interconnected cerebral ventricles?
- lateral ventricles that are winged-shaped cavities filled w CSF –> made by a network of interconnected blood vessels (known as choroid plexus) **this lines the ventricles
- Cerebrospinal fluid (CSF)
- suspends the brain
- acts as a shock absorber
- provides protection from mild head blows
- provides stable enviro for optimal brain function
- CSF flows from the 2 lateral ventricles to the 3rd and 4th ventricles ( this lies on the brain’s midline/into the cerebral aqueduct
: the cerebral aqueduct is a canal that runs down the length of a spinal cord
- the CSF bathes the brain/circulates to the space between the lower layers of the meninges
**where its absorbed/deposited into the venous bloodstream
What does the CSF perform?
- several vital brain functions
- CSF suspends the brain –> to make it neutrally buoyant so it acts like 1/30 of its actual mass
- acts as shock absorber **providing the brain w important protection from mild blows to the head
- chemical content of CSF = precisely regulated to provide stable environment for optimal brain function
**slight changes to chemical composition = cause dizziness/fainting
describe the sagittal brain section
- internal features of the brain
brain midline
- (A) A section in midsagittal plane (separates the hemispheres)
**cutting through the brain vertically from front to back = sagittal section
**if you make a cut down the brain’s midline = midsagittal plane
- (B) a medial view of the brain’s midline structures
–> includes the subcortical structures that lie ventral to the corpus callosum (this goes all around the ventricles)
such as:
- neocortex
- 3rd ventricle
- 4th ventricle
brainstem
- cerebellum
Corpus callosum
- long band of white matter that runs much of the length of the cerebral hemispheres
- 200 million nerve fibers that join 2 hemispheres / allow them to communicate
subcortical regions
- make intimate reciprocal connections w cortical regions –> that process sensory, perceptual, cognitive, and motor functions
EX: when cortical areas perceive a threat (such as an angry dog)
–> they communicate w subcortical regions that have begun to increase breathing / heart rate (through the sympathetic NS)
–> supports another principle of CNS organization
- the concept that redundant/overlapping functions exist at many levels of the nervous system
What is Microscopic Inspection: Cells & Fibers?
What is Microscopic Inspection: Cells & Fibers?
What are the Cortical Layers & Gilia?
- these are stains that allow us to see white matter and grey matter (in greater detail by dyeing their cells w stains)
- points out the layers of the cortex (one that is not purple = white matter)
- both figures show stained subcortical regions composed of clusters / nuclei (sing, nucleus) –> of similar cells
**although each layer looks different – both form functional units in the brain
- by using stains, we can see borders of subcortical nuclei more clearly
What are Neuronal Connections?
- Neurons are connected by one another by fibers called = axons
- when axons run along together they form something called = nerve tract
Tract
- collection of nerve fibers in brain/spinal cord
EX: pathway from the eye to brain = optic nerve
Nerve
- bundle of fibers outside the CNS
EX: pathway from cerebral cortex to spinal cord = corticospinal tract
What is the Central Nervous System: Mediating Behavior?
- learning how parts of the brain function to produce complex experiments
–> you need to understanding the brain’s functional anatomy
–> this is learning the names & functions of the 3 major CNS components
1. spinal cord
2. Brainstem
3. Forebrain
Describe the Spinal Cord (its functions)
- controls most body movements
- act independently of the brain (meaning the spinal cord doesn’t need the brain to create movements – it can do it on its own)
**this is through the somatic nervous system
EX: a chicken running with its head cut off – this is bc the spinal cord is acting independently from the brain
Spinal Reflex
1. automatic movement (bc the brain has a hard time inhibiting this spinal reflex)
- hard to prevent
: this is bc the brain can’t inhibit
EX: Knee-jerk reflex (patellar tendon)
–> the sensory input causes our lower leg to kick out
Spinal cord’s complexity
1. not a singular structure –> its a set of segmented switching stations
- each spinal segment receives info from discrete part of the body
–> then sends out commands to that area
Spinal Nerves
1. this is part of the SNS
- carries sensory information to the cord from the skin, muscles/related structures ***and sends motor instructions to control each muscle
Describe the brainstem and its functions.
**this moves dorsally (meaning moving up)
- begins where the spinal cord enters our skull
- receives afferent (incoming) nerves coming from all body senses
- sends efferent (outcoming) nerves out to control body movements
**except most complex movements of fingers/toes
**creates sensory world & directs movements
- responsible for most life-sustaining behavior
- 3 regions
1. hindbrain
- midbrain
- diencephalon: “between brain” - it borders the brain’s upper/lower parts)
What are the brainstems structures?
Figure 2-16A
- A: shows the medial view & relationship of the brainstem to the cerebral hemispheres
Figure 2-16B
**compares shape of the brainstem regions to lower part of your arm when held upright
1. Hindbrain
- forearm : this is analogous to your hindbrain
- its long & thick
**important in motor functions (in humans = anterior (ventral)
- Midbrain
- Wrist: Short & compacted / analogous to midbrain
**important in sensory functions (dorsal - in humans: posterior) - Fist
- fist: analogous to diencephalon / bulbous like a fist
**important in integrative sensorimotor tasks)
Describe the Hindbrain and its functions.
- evolutionarily the oldest part of the brain
contains
1. cerebellum
- important in controlling complex movements
- reticular formation
- netlike mixture of neurons (grey matter) and nerve fibers (white matter)
- nuclei of reticular formations nuclei = localized into small patches along its length
**each have special functions in stimulating the forebrain (such as waking up from sleep)
- pons
- nuclei in pons receives inputs from the cerebellum
- forms bridge from it to the rest of the brain (the meaning of pons = bridge)
- medulla
**this is at the rostral strip of the spinal cord
- medulla’s nuclei regulates vital functions (breathing/cardiovascular system)
**so a hit to the back of the head can kill you (breathing stops if hindbrain controls centers = injured) - controls various motor functions (that range from breathing to fine movements)
EX: those used in dancing - cerebellar size in humans = related to cognitive capacity
EX: apes show expansion of the cerebellum – correlates w increased capacity for planning/ complex behaviours (such as tool use & language)
**one of the largest structure in the human brain
–> its size increases w physical speed & dexterity of a species
EX 1: slow moving animals (sloths) have smaller cerebellum relative to brain size
EX 2: animals that have rapid movement (hawk or cat) - have large cerebellums compared to their overall brain size
describe the structures of the Hindbrain
Principle hindbrain structures
- integrate voluntary/involuntary body movements
**takes over distinct instincts (in terms of movements)
EX: Blinking –> happens all the time (we eventually need to blink) **involuntary aspects come from the hindbrain
Reticular formation
- called the reticular activating system
- important part of our brain: attention, arousal, and mediates sleep
-EX: when you dream, our brain is just as active when we are awake (basically looks the same)
**this involves the motor cortex
–> when ppl move or sleep walk (you can tell something is going on in their brain stem)
Human cerebellum
- has left/right hemispheres: these are extensively folded cortex w gray/white matter/subcortical nuclei
Describe the Midbrain & its structures
structures
- critical for producing orienting movements, species-specific behaviors, & pain perception
- tectum (roof)
- sensory component thats dorsal (posterior in upright humans)
- receives massive amount of sensory info from the eyes & ears
EX: the optic nerve sends large bundle of fibers to superior colliculus vs inferior colliculus receives much of its input from auditory pathways - colliculi function processes sensory info but also produces orienting movements (movements related to sensory input EX: turning the head to see the source of a sound)
**the colliculi has a tactile map –> auditory and visual systems must share a map of the external world so that the ears can tell the eyes where to look (
- tegmentum (floor)
- motor structure that’s ventral (anterior in humans) to the tectum
Figure
- shows the tegmentum in cross section: reveals various nuclei
**mostly movement-related functions
EX: several tegmental nuclei control eye movements
- red nucleus
- controls limb movements (not in snakes)
**maintains posture & muscle tone
–> more iron = this is why the nucleus is more red - substantia nigra
- connects to the forebrain (important in initiating movements)
EX: Parkinson’s disease
- related to the destruction of the substantia nigra
- Periaqueductal gray matter (PAG)
- made up of cell bodies (these cell bodies surround the aqueduct –> which joins the 3rd and 4th ventricles)
- contains circuits that control species-typical behaviors (EX: female sexual behavior)
- important for instinctual movement
EX: when we hear something, we become alert
Pain perception
- these nuclei (above) plays important role in how opioid drugs can modulate pain
EX: working out: when we’re doing muscle movements it’s painful but it makes us feel good
Describe the Diencephalon
- “between brain” : integrates sensory/motor information on its way to cerebral cortex
**2 principle parts = hypothalamus & thalamus
- Hypothalamus
- Diencephalon structure
contains many nuclei associated with:
a. temperature regulation
b. eating
c. drinking
d. sexual behavior
**has a lot of drives
- hypo - “below” = lies below the thalamus in each hemisphere (along the brain’s midline)
- composed of 22 small nuclei / nerve fiber systems that pass through it
critical functions
1. control body’s production of hormones (can be done through its interactions w pituitary gland)
- Thalamus
- diencephalon structure: information from all sensory systems are:
a. organized
b. integrated - projected
**into appropriate region of the neocortex
- has a one in each hemisphere
: lies just to the left of the brainstems tip - larger than the hypothalamus (20-odd nuclei)
functions
1. organizer
- integrator of sensory info travelling to the cerebral cortex from all sensory systems
EX: the optic tract: sends info through larger fiber bundle to thalamic region called = lateral geniculate nucleus (LGN)
LGN
- processes some of the info / sends it to the visual region in the occipital lobe **in each hemisphere
Dorsomedial thalamic nucleus (DTN)
- projects to the frontal lobe
- performs integrative tasks
- plays vital role in attention, planning, abstract thinking, memory
Describe the Hormonal Hierarchy
**this is the way in which the hypothalamus tells us to do things through the bloodstream
**can also be released throughout different parts of the day
- in response to sensory stimuli/cognitive ability
- hypothalamus produces neurohormones (this enters the anterior pituitary through veins / posterior pituitary through axons) - through instructions from the above releasing hormones
–> pituitary sends hormones into bloodstream (to target endocrine glands) - Endocrine glands release their own hormones (that stimulate target organs) **including the brain
What is the forebrain & its structures?
- largest region of the brain
- regulates many mental activities (that range from: perception, planning, emotions, memory)
basal ganglia
- controls voluntary movement
- has a role in cognitive functioning
- major internal/external forebrain structures
1. integrate sensation
2. motivation
3. emotion
4. memory
**to enable advanced cognitive functions (such as thinking, planning, and using language)
forebrain structures
1. neocortex (cerebral cortex)
2. basal ganglia
3. limbic system
4. neocortex (new bark)
5. allocortex
What is the cerebral cortex?
- contains concentric rings of allocortex
: 3 layered cortex & 4 layered cortex: allocortex - Allocortex = “other bark” –> refers to both 3 & 4 layered cortex
Allocortex role
- controlling motivational/emotional states
- certain forms of memory
: 6 layered cortex: neocortex
- “new bark” : this is the tissue visible when we view the brain from the outside
- expanded neocortex = unique to mammals
Primary function
- constructs perceptual world & responds to that world
most of forebrain = volume of 80% (most expanded by evolution)
**we have a bigger cortex compared to different primates
- involves folding of neocortex (sulci & gyri)
What are the 3 primate brains?
- monkey
- chimpanzee
- human
- pattern of sulci/gyri formed by folding of neocortex varies across species
- smaller brained mammals = have no sulci or gyri
- larger-brained mammals = have gyri that form longitudinal pattern
Describe the Forebrain: Allocortex
composed of 3 & 4-layered structures includes:
- hippocampus
- shaped like a seahorse
- involved in consolidation: process when short-term memories that are solidified into long-term memories
- decrease (in terms of number of layers when we get closer to it)
Destruction of the hippocampus
1. leads to problems w navigation
2. finding your way around
3. difficulties w word finding
- part of the amygdala
- meaning “almond”
- crucial role in anxiety & fear
Removal of the amygdala
- produces startling changes in emotional behavior
- cingulate cortex
- lies above the corpus callosum (close to the midline)
- involved w emotion formation, processing, learning, and memory
- highly influential in linking behavioral outcomes to motivation
- several structures **that make up the olfactory system
- olfactory bulbs
- receptors
- pyriform (smell)
- cortex in front of brain
- vomeronasal organ (VNO): important for fairmone **more important for other species than us
EX: experiment done on women based on men not wearing deoderant - gave it to women to examine which shirt they liked the most/found attractive
- important to smell each other to feel attraction
- tend to not be attracted to ppl in your own family (more things go wrong when you do)
- other related areas
- Limbic system: disagreement about structure (obsolete)
- important for emotion
what is the concept of the limbic system?
- group of structures between neocortex & brainstem
: principle structures
1. Amygdala
2. hippocampus
3. cingulate cortex
**more important than emotion
limbic system regulates:
1. emotional & sexual
behaviors
- this is due to the concept being dominated by Freud (who emphasized the roles of sexuality/emotion) in human behavior
- simple step to thinking that the limbic structures played a central role in sexuality and emotion
- memory
- spatial navigation
EX: asked people to imagine themselves going into a room (this activated the hippocampus) **rats who have a damaged hippocampus can’t find their way around the maze
Controversial history in neuroscience
1. obsolete term
- recent view: specific circuits for specific functions can be traced through several (allocortical, neocortical, & brainstem structures)
What is the Olfactory system?
olfactory bulb
- located at the very front of the brain (lies at the base of the forebrain)
- connects to receptor cells (that lies in the nasal cavity/ sends most of the input to the pyriform cortex then to amygdala and dorsomedial thalamus)
- the organ responsible for our sense of smell **and providing input to other brain areas responsible for our perception of smell
**important role in aspects of our feeding and sexual behavior)
**relatively small
Principle structures
1. pyriform cortex
- olfactory bulb sends most of its input to this specialized region
**this is part of the allocortex (on the brain’s ventral surface)
- amygdala
**from there (above): sensory input progresses to amygdala - dorsomedial thalamus
*sensory input also progresses here
**sensory input that progresses to amygdala and dorsomedial thalamus routes to the frontal cortex
Vomeronasal organ (VNO)
- sensory neurons that detect pheromones & molecules that carry information between individuals of same species
- axons from these neurons project to accessory olfactory bulb (which connects to amygdala / hypothalamus)
Important role
- reproduction and social behavior in many mammals
*Specific function disputed
- functionality in humans = controversial
- thought to be more relevant to other species than humans
what are the Characteristics of Neocortical Layers?
The 6 layers of the neocortex : Distinct Characteristics
1. different layers have different cell types
- Density of cells varies among layers
*varies from layer to layer –> ranges from virtually no cell in layer 1 (top layer) to very dense cell packing in layer 5 - differences in appearance relate to function and region
- cytoarchitectonic map
- map of neocortex based on the organization, structure, and distribution of the cells
EX: viewed through a microscope –> the sensory neocortex in the parietal lobe has larger layer 4
–> motor cortex in the frontal lobe has larger layer 5
**layer 5 = afferent
**layer 6 = efferent
(makes sense that sensory region has larger input layer (whereas motor region has large output layer)
Influences
**many behaviors
- cravings
- lust
- interpretation of abstract concepts
- words
- images
**this also creates reality
The Neocortex
- deals with complex behavior
- the cortex does the most in creating our reality
EX: almost like taking everything apart at first - when we see something (edge) neurons will add to a particular color
–> the brain is dismantling things & then putting them back together
EX: something as complex as AI
–> trying to make them human like **however, sarcasm is hard for them
What is the Neocortical layering?
The neocortical layering figure 2-25
- layer 4 is thick in the sensory cortex & thin in the motor cortex
**this is due to abundant afferent sensory info from the thalamus connects to layer 4
- layers 5 and 6 in the motor neocortex is thick and thin in the sensory neocortex
- efferent motor info in layer 5 = makes up corticospinal track –> connecting motor neocortex to the spinal cord **to generate movement
- layer 6 connects to other cortical areas
Additional Notes
- each one of the layers in figure 2-25 have different functions
- if its thicker in one particular layer (it means that its important)
What is the Cytoarchitectonic Map of the Neocortex?
brodmann (1909)
- defined areas based on organization/characteristics of the cells he examined
Figure
- the regions shown in color are associated with simplest sensory perceptions
1. touch = red
2. vision = purple
3. hearing = orange
- the neocortical areas that process sensory info (are more extensive than Brodmann’s basic areas
- staining neocortical tissue can reveal chemical differences between cells & layers –> some regions are rich in one chemical, others rich in another **these differences relate to functional specialization of different neocortical areas
what are the cortical lobes?
- nearly symmetrical left & right hemispheres –> that are separated by the longitudinal fissure/central sulcus
- function & consequences of injury **need to memorize this
1. frontal lobe - sometimes called the brain’s executive bc it integrates sensory/motor cortex
frontal lobe injuries:
- difficulty organizing & evaluating their ongoing behavior
- difficulties planning the future
- parietal lobe
- tactile
Parietal lobe injuries:
- difficulty to identify / locate stimulation on skin
- can contribute to deficits in moving the arms/hands to points in space
- temporal lobe
- visual
- auditory
- gustatory
Temporal lobe injuries:
- difficulty recognizing sounds
- can still recognize that they’re hearing something
- cause difficulties in processing complex visual information (such as faces)
- occipital lobe
- visual
Occipital lobe injuries:
- deficits in processing visual information
- can still perceive light vs dark
EX: individuals who have a damaged occipital lobe is unable to identify either the shape/color of objects
**defined anatomical regions that include many functional zones
What are the Cortical boundaries?
dorsal view of the brain
- right hemisphere
- left hemisphere
**both separated by the longitudinal fissure
Lateral View of the Brain
1. frontal lobe (motor & executive functions)
- Motor behavior
- Central sulcus
- Parietal lobe (tactile functions)
- occipital lobe (visual functions)
- temporal lobe (visual, auditory & gustatory functions)
What is the Basal Ganglia, its functions, and structures?
location & function
- its a collection of nuclei (below the white matter of the neocortex)
**can be divided into different regions
- controls voluntary & involuntary movement
Principle structures
1. caudate nucleus
- works towards modulating movements
- putamen
- globus pallidus
Related Disorders
- Parkinson disease
- tourette syndrome : tends to have ticks & motor ticks
**this is due to the basal ganglia not stopping the movements
–> they tend to have smaller basal ganglia (this can be due to genetics but harder to stop movements)
