The Human Brain L1. Flashcards
What does cerebellum mean?
Small brain
What constitutes the Brain Stem?
Mid brain, pons and medulla
What constitutes the Hindbrain?
Pons, Medulla and cerebellum
What is the difference between the brain of Rats, Cats, Monkeys and Humans?
Forebrain
-the flat cerebral cortex becomes larger in size in a smaller space
Size and complexity of the forebrain increases through the mammalian series, As there are more folds as the animal has developed a more complex life
Rat can see cerebellum behind Forebrain, cat has partially seen cerebellum, monkey hardly and totally hidden in human
How thick is the cerebral cortex?
Cerebral cortex is a flattened layer of 6 cells
5-7 mm thick in humans
If extended, how long is the brain?
13000 ft
What is the organisation of brain like?
Highly organised
Gyri form a regular patter of gray matter, with white matter underneath
What is hemispheric control like?
A hemisphere of the brain controls the opposite side of the body
What is the most critical part of the brain?
Forebrain
Is larger and more complex in humans than other animals
Large, developed and highly complex
allows you to have thoughts, communication, memories, feelings, visions about the future, to talk, remember
What is the cerebral cortex?
Covers the cerebrum Gray matter Billions of neurons in layers Flattened layer of about 6 cells 5-7mm thick in humans
What is the embryonic development of the brain?
Rapid increase in brain size
Gray matter enlargers faster
What constitutes the cerebrum?
Outer cerebral Cortex of Gray matter
Internal region of cerebral white matter (axons)
Gray matter nuclei deep within the white matter
What is gray matter?
Dendrites and cell bodies
Its faster enlargement causes the cortical region to roll and fold upon itself
Receives and integrates incoming/outgoing information
What is white matter?
Bundle of Myelinated Axons of neurons
Where sensory inputs and motor outputs travel
What is a gyrus?
Fold
Convolution
Gray matter (5-7mm variable thickness)
White matter underneath
What is a sulcus?
Shallow gap/groove between folds
What is a fissure?
deep sulci/groove
Most prominent is the Longitudinal fissure between hemispheres
How many neurons does the brain contain?
100 billion
What is the Longitudinal fissure?
most prominent fissure/sulci
Separates the Cerebrum into Right and Left cerebral hemispheres (halves)
Has Falx cerebri within
What connects the cerebral hemispheres?
Corpus Callosum connects the the two cerebral hemispheres Internally
Broad band of White matter axons extending between the two hemispheres
How are the lobes of the brain named?
after the bones that cover them (they are under)
What is the weight of the brain?
1.5 kg
20g of brain per 1kg of body weight
What is the role of the cerebellum?
co-ordinates muscles/movement
What is the Transverse gyrus of Heschl?
Heschl’s gyrus
Located transverse on the temporal gyrus
Within the 1 Primary Auditory area
therefore Processes sound
What is on the frontal gyrus?
Triangular part of the inferior frontal gyrus
What is in the frontal lobe?
Pre central gyrus Pre central sulcus Superior frontal gyrus Superior frontal sulcus Middle frontal gyrus Inferior frontal sulcus Inferior frontal gyrus Triangular part of the inferior frontal gyrus
What is in the parietal lobe?
Post central gyrus Post central sulcus Superior parietal Lobule INTRA-parietal sulcus Inferior parietal Lobule Supra-Marginal Angular Gyrus + Angular Gyrus
What is in the occipital lobe?
Parieto-occipital sulcus
Pre occipital notch
What is in the temporal lobe?
Transverse Temporal Gyrus of Heschl Superior temporal gyrus Superior Temporal sulcus Middle Temporal gyrus Inferior Temporal sulcus Inferior Temporal gyrus
What does “Primary” mean?
Primary=takes a critical role
What is the Primary Motor Cortex?
Voluntary movement - Each region controls voluntary contractions of specific muscles/groups of muscles on the opposite side of the body
Somatotopically organised (according to the distorted muscle map of the body called the motor homunculus)
Located in the pre-central gyrus in the frontal lobe
down –>up (fingers eyes, vocalisation/head&neck (face=1/3))–> (fingers, head, arms) –> (thorax, abdomen, nipple) –> (leg thigh) –> foot
Muscles involved in skilled, complex or delicate movements required a greater number of brain cells to control that movement therefore they have more cortical area devoted to it
(thorax, abdomen and nipple =smaller region= more automatically controlled)
Dominated by face, hands, forearms
Electrical stimulation at any point in the primary motor area cases the contraction of specific muscle fibres on the opposite side of the body
What happens if there is electrical stimulation in the Primary motor area?
Electrical stimulation at any point of the primary motor area causes contraction of specific skeletal muscle fibres on the opposite side of the body
What proportion of the primary motor cortex is take up to control the face?
1/3
massive control
What is the primary motor cortex dominated by?
Face, hands and forearms
What is the Primary Somatosensory Cortex?
Conscious appreciation/perception of sensation -“touch, pressure, pain & temperature”
Located posterior to the central sulcus, in the post central gyrus of the parietal lobe
Each region receives nerve impulses from a specific part of the body (input from skin), and projects sensation out to the skin
Somatotopically organised according to the distorted body map of the sensory homunculus
Size devoted in cortical area which receives impulses depends on the number of receptors present (not the size of the body part)
Larger regions-lips, tongue, face, fingertips/hands - very discriminative and very precise
Highly discriminative - can pinpoint somatic sensations
What is the Primary Somatosensory cortex dominated by?
Lips, Tongue, Face, Fingertip/hands
highly discriminative and very precise
What is the Primary Visual Cortex?
Located on the posterior tip of the occipital lobe, seen best on medial surface next to the longitudinal fissure
Surrounds the Calcarine sulcus
Receives Visual information/Visual perception-functional relationship with vision
Visuotopically organised (according to the map of the visual field) and Retinotopically organised (according to the map of the retina)
Highly acute
Central part of the visual field is: Discriminative, Upside down, Tip of the cortex
Peripheral=Deep part of the Cortex
Very discriminative sensation in the middle
Visual field on the right side goes to the opposite side of the brain
Brain flips the image
Right and Left side’s combine to give 3D panoramic vision
There is communication with the visual field on the opposite side, is a continuous representation in the brain
Supplementary visual field is involved with movement and colour, and adds quality
What is Phantom pain?
to do with Primary Somatosensory cortex
Project sensation to region that is effected
amputation below knee with no leg or foot
theoretically no sensation from leg or foot now
But if you knock the end of the stump where the nerve is now a crumpled nodule, they still claim to see their foot- still interpret information from foot
-Still project sensory information out to the skin
What is the overall functional role of the Forebrain?
CONSCIOUS appreciation
end points of different functions
What is the Primary Auditory Cortex?
Located superior part of the temporal lobe, near the Lateral Fissure
Receives information from sound, from the opposite ear
Involved in auditory perception
Transverse gyrus of heschl located 2.5cm deep into the lateral fissure, receives input from ear on opposite side
Tonotopically organised- according to frequency/pitch = Front=Low freq. and Back=High freq.
What is a stroke?
CVA = CerebroVascular Accident
Characterised by an abrupt onset or persisting neurological symptoms such as :Paralysis or Loss of sensation
a. Intra-cerebral haemorrhage from blood vessels
b.blood clots
c. atherosclerosis –> formation of cholesterol-contianing plaques that block blood flow
Stroke on right side affected by opposite side of the brain
Risk factors: - High BP blood pressure, High blood Cholesterol, Diabetes, Smoking
How does a stroke affect the Primary Motor cortex?
Lesion would Paralyse muscle movement on the Opposite side of the body
the Particular muscle(s) paralysed would depend on Where on the 1 Primary motor cortex/motor homunculus the lesion occurs
How does a stroke affect the Primary Somatosensory cortex?
Lesion would result in Loss of Sensation on the opposite side if the body
The particular area with loss of sensation depends on Where on the mapping of the 1 Primary somatosensory cortex/according to the sensory homunculus
How does a stroke affect the Primary Auditory cortex?
A lesion would lead to a Loss of Hearing in the opposite ear
How does a stroke affect the Primary Visual cortex?
A lesion would result in a Loss of vision in the opposite eye
What are features of the Left Hemisphere?
Dominant side
Verbal language area/centres used to Talk
80-90% of people are Right handed
Hearing, Speaking, Reading, Writing
-to accumulate knowledge and expand societies
What are features of the Right Hemisphere?
Non Dominant side
Non-verbal language
LH= Some still have a dominant Left Hemisphere, Few other’s have it divided between the two hemispheres
1. Non-verbal language area (body language) (90% of communication)
2. Emotional expression (language) - modulation of speech
3. Spatial skills (3D) - shape of the object
4. Conceptual understanding
5. Artistic and Musical Skills - someone who can’t talk could sing
Large extent on right hemisphere but not entirely
What 5 things would a lesion on the Right hemisphere result in?
Injury to non-verbal language areas
- Loss of Non-verbal (body) language
- Speech lacks emotion
- Spatial disorientation
- Inability to recognise familiar objects
- Lack of musical appreciation
What areas are affected when there are Perceptual problems?
2 Secondary areas
What is Wernicke’s area?
Wernicke’s Speech Area
Association area
Enlarged region on the Left hemisphere
Located as a broad region in the Left Temporal and Parietal Lobes
UNDERSTANDING- analyses/interprets meaning of speech by recognising the spoken word
Has accumulate overtime the meanings of words
ACTIVE= as it translates words–> thoughts
Corresponding right hemisphere add emotional content/expression
What is Broca’s area?
Broca’s Speech Area
Motor area
Located in the Frontal lobe close to the Lateral fissure/sulcus
Inferior Frontal Gyrus under the motor cortex
Triangular
Motor control/articulation/pronunciation of speech
Has accumulated motor information to allow for the production of speech
From Broca’s speech area nerve impulses pass to the pre-motor cortex regions that control the Larynx, Pharynx and mouth, to move in a precise way, resulting in Specific, co-ordinated muscle contractions, to speech clear words
The co-ordinated contraction of speech and breathing muscles allow you to speech your thoughts
Simultaneous impulses propagate from here to the 1 Primary motor cortex, and also controls breathing muscle to regulate flow or air past the vocal cords
What is the Arcuate Fasiculus?
bundle of fibres which connects Wernicke’s Speech area (sensory) with Broca’s speech area (motor)
-if affected Conduction aphasia
What are the frontal eye fields?
Located in the Frontal cortex
Pre motor area
controls Voluntary scanning moments of the eye
-what you of when reading
What is Exner’s Area?
Activates muscles in order to Write
has accumulated memory of how to write and trains cells in the area so are able to write words
Located In-front of the 1 Primary motor cortex’s area which controls the fingers
Corresponding Right Hemisphere controls intelligence, spatial, art and musical skills
What is the SupraMarginalAngular Gyrus?
Located as part of the Inferior Parietal Lobule
Critical for Reading and Writing
These neural cells have Stored up the Patterning of -Words, Shapes and Meanings
What is an Aphasia?
disorder of speech associated with the brain
What is an Ataxia?
disorder of muscle co-ordination due to damage (trauma or disease) to the cerebellum
Results in Unco-ordinated movements or Loss of balance
What happens when there is an aphasia in Wernicke’s Area?
Hear, but cannot understand/recognise speech
Still able to speak and hear, but lack of understanding is due to inability to arrange words in your head in a coherent fashion
is the area associated with Understanding and recognising spoken words “disorder of speech”
Sensory aphasia
Fluent aphasia (as you can still from words)
What happens when there is an aphasia in Broca’s Area?
Problem’s pronouncing words
Still have clear thoughts, but cannot form words, pronounce speech/words
is the area responsible for the articulation of speech (motor speech area)
This is due to the muscle being Unable to produce co-ordinated speech
Note: can still Use the muscle of the speech apparatus, but this critical region No Longer Co-ordinated the speech muscles
Motor aphasia
Non-fluent aphasia (as can no longer form words)
Motor/speech aphasia
Expressive aphasia
What happens when there is an aphasia in the Arcuate Fasiculus?
Separates input from output -reply unrelated due to disconnection
The pathway connecting Wernicke’s and Broca’s area
Individual will still Hear and Understand spoken words, and still Pronounce/Speak clearly with co-ordinated speech muscles, but their Reply will be Unrelated to the question- as input and output are no longer Connected
Damaged by a tumour deep in the Temporal Lobe
Conduction aphasia
Dis-conduction aphasia
(also Fluent aphasia as you can still produce words)
Where is the Central Visual field located?
Tip of the 1 Primary Visual cortex
Where is the Peripheral Visual field located?
Deep part of the 1 Primary Visual cortex
On which surface is the Parieto-occipital sulcus shown better?
Medial surface
On which surface is the Primary visual cortex shown better?
Medial surface
What is the Corpus Callosum?
“body” “hard”
Broad band of White matter of Axons which Extends Internally between Hemispheres to connect them
What is the Falx Cerebra?
Longitudinal fissure between the cerebral hemispheres
What are association areas?
complex areas
Processes information received by the primary cortexes
Most highly developed in humans (rats have hardly any)
-these are the areas which allow us to carry out really complex functions
Complex neural interactions/functions , which are not entirely distinct
Connected via association tracts
Which 5 things does the Frontal Association cortex control?
FMCBIP frontal- Mood (e. Temporal A.c.) Cognitive function (how you think) Behaviour (behavioural profile) Intelligence (w. Temporal A.c.) Personality (hard to define. personality profile) - Massive association area Hugely developed in humans Very important Very complex functions Tumour/Blood clot pushing down = change in personality
Which 2 things does the Parietal Association cortex control?
Spatial skills 3D recognition a. shapes b. faces c. written words d. concepts e. abstract perception - present on both sides Little more on one side for the written word Input from all sensory areas- bring info tpgether
Which 4 things does the Temporal Association cortex control?
AMMI
Aggression
Memory (short term very important, longterm still important) (critical, allows for individual and worldly advancement)
Mood (w. Frontal)
Intelligence (w. Frontal)
-each feature is Not specifically localised- is a complicated relationship
-
rats have hardly any temporal association area
Memory is critical, allows for advancement individually and collectively as humans
Short term memory is slightly more important
Intelligence is really complex and hard to define functional area
What is special about the features controlled by the association cortexes?
Each features is NOT specifically localised
-It is a complicated relationship
