The Central Nervous System And Cerebral Cortex Flashcards
Nervous system
Central nervous system- brain and spinal chord
Peripheral nervous system
Anatomical directions
^ dorsal - up towards sky
> Posterior/Caudal -towards back
V- ventral -down towards ground
<- anterior/ Rostral - towards front of structure
Neuoraxis
Imaginary line running through the spinal cord and the front of the brain
Animals who walk on 4 legs- neuoraxis is a straight line
Humans- neuoraxis bends
Anatomical directions
Lateran <————-> out towards sides
Medial ——–> <——— towards the middle
Ipsilateral
Same side
Contralateral
Opposite side
Frontal plane
- sectioned vertically front to back
Superior
Above
inferior
Below
Saggital plane
Vertically from side to side - side of head
Horizontal plane
Top to bottom - birds eye view
Blood supply
Receives 20% blood flow from the heart
Two major sets of arteries serve the brain
-Vertebral arteries- serves caudal portion, enters the base of the skull
-Internal carotid arteries- serves the rostaral portion, ascends the left and right sides of the neck
-Join together to form the basilar artery
-Stroke- any condition which blocks blood flow to the brain
Blood brain barrier
-Nutrients delivered to the brain (oxygen and glucose) and waste products are extracted by capillaries which branch of the arteries
- prevent molecules above a certain size from entering the brain
-Relaxed in area postrema- initiates vomit reflex, detects toxic substances in the blood
-Blood brain barrier means if any viruses that can penetrate the barrier stay with us for life-
-Causes issues in medicine- cant pass the blood Brian barrier- like In brain cancer- cant pass through
The meninges
-Tough protective tissue surrounding the brain and spinal chord
Three layers
-Dura matter- thick and tough outer layer
-Arachnoid membrane- soft and spongy web-like middle
-Pia matter-lower layer closely attached to the brain and spinal chord
- has pain receptors
-Menengitis- inflammation of the meninges by viral or other means
The ventricular system
Brain is soft and prone to injury
Brain is encased in protective bath of cerebrospinal fluid (CSF)
CSF supplied by 4 hollow interconnected chambers called ventricles
Reduced weight- approx 1400g to approx 80g
Hydrocephalus- reduced flow of spinal fluid
Should be clear if extracted- if not could mean some sign of infection
The forebrain
-Outer layer of brain- top of brain
Telencephalon
-Cerebral cortex
-Limbic system
-Basal ganglia
Diencephalon
-Thalamus
-Hypothalamus
Telencephalon- cerebral cortex
Lateral fissure- deep groove
Central sulcus- groove down
Gyrus
Suculus- small groove
Longitudinal fissure- groove down the middle
Connected by bundle of nerve fibers called the Corpus collosum
Cerebral cortex
Frontal lobe(back)- planning,problem solving ect
Pariateal(top)- taking info from our senses
Temporal(bottom)- facial recognition
Occipital (front)- visual information
Telencephalon- limbic system
Hippocampus, amygdala, mamillary body, fornix
-Most important structures are the hippocampus and the amygdala
Hippocampus- crucial for learning and memory, dysfunction linked to memory impairment
H.M- 1953- age 27 hm had an operation to remove medial temporal lobes to control his life threatening epilepsy. Retained normal IQ working memory implicit memory,executive function but lost the ability to form new memories
Clive wearing
-Fell I’ll with herpes simplex virus which attacked the nervous system causing damage to the hippocampus, temporal lobe and frontal lobe
Amygdala- crucial for emotion and motivation,dysfunction linked to anxiety
Telencephalon- the basal ganglia
Putamen, globis pallidus, substantia Nigra
Primary function- voluntary control of movement
Diencephalon- the thalamus
-Relay station- receives information processes ot then passes that on to other areas of the brain
-Receives input from the sensory systems and relays this information to the sensory processing areas of the cortex
Can this influence the whole brain
Diencephalon- the hypothalamus
-Not a single structure- 22 small nuclei and the pituitary gland
-Controls autonomic nervous system and the endocrine (hormone) system
-Regulates survival behaviours and emotional behaviour
Four Fs (feeding,fleeing,fighting and sexual behaviour)
The mesencephalon
Tectum- two main structures
-Inferior colliculus- part of the auditory system
-Superior colliculus- part of the visual system
Tegmentum includes-
Reticular formation- sensory processing, sleep,arousal,attention,muscle tone, movement and reflexes
Red nucleus and substantia nigra- important components of the motor system
The hind brain - metencephalon
The cerebellum (little brain)- coordinates our movements. Damage- eg cerebral palsy impairs walking,balance,posture, and skilled motor activity
The pons- involved in sleep and arousal
The hindbrain- mylencephalon
Contains medulla oblongata- borders the spinal cord
Controls vital functions such as control of breathing
The spinal cord
Located within the spinal column
Communicates with sense organs and muscles
Two fibre pathways
Dorsal roots sensory information
Ventral root-motor information
Infiltrating the brain- alcohol
Cerebral cortex- decrease in inhibitory behaviour, slows down information from the senses, inhibits thought processes
Limbic system- exaggerated emotion,memory loss
Hypothalamus and pituitary- sexual behaviour,urine excretion
Medulla- sleepy,unconscious
The frontal lobe- motor cortex
-Concerned with the generation of movement
-Each part of the body has its own specific area of representation in the motor cortex
-Contralateral control
-Damage-loss of fine movement control, problems with fast automatic actions,impaired movement of facial muscles
The frontal lobe- brocas area
-Area in the left hemisphere of the frontal lobe
- in charge of producing speech
-Identified by Paul broca- reported case of man who had lost the power of speech through could still make speech noises and understand speech
-Impairment- Brocas aphasia- slow deliberate speech
The frontal lobe- prefrontal cortex
Involved in
-Working memory- keeping relevent information in memory for a short period of time,problems on delayed response tasks
-Planning and carrying out sequences of actions
-Shifting attention
-Inhibiting inappropriate responses and behaviour In social situations
Case of Phineas Gage
- railway worker in 1848
-Explosion went wrong
-Iron rod fired through cheek and out top of skull
-Didn’t loose conscious
-Notable differences in social behaviour
-Before described as hardworking and dependable
-After- rude, unreliable,swear aggressive ect
-Case based on anecdotal evidence
The parietal lobe- somatosensory cortex
- processes sensory information from different parts of the body
-Similar to motor cortex each part of the body has its own area of representation
-evidence that experience can modify representation
-Contralateral
-Phantom limb- neurons that took information in for that limb get taken over by other processes - people who wear a prosthetic limb go through less neural reorganisation
The parietal lobe
-Primary function- integrates sensory and motor information
-Key functions- spatial navigation and perception
-Monitors all information about body position and passes it to all areas involved in movement
-Damage- problems in detecting sensory information, difficulty in recognizing objects they can touch but not seen, problem with spatial ability
-Damage to right pariateal lobe- sensory neglect - people ignore objects on one side of visual field (draw half of lock or house ect)
The temporal lobe- Wernicke’s area
-Area in the left hemisphere of the temporal lobe
-Involved in the comprehension of speech
-Discovered by german neurologist Carl Wernicke- found that damage in the region disrupted speech
-Impairment- Wernicke’s aphasia- fluent speech and normal speech sounds but speech fails to convey a rational meaning. Also an inability to understand words
Damage to equivalent area in the right temporal lobe- problems in processing music
The temporal lobe- primary auditory area
-Mostly hidden from view in the grooves of the cortex,responsible for the processing of information from the ear- involved in the interpretation of sound
Temporal lobe also involved in complex visual processing eg faces
Damage to the right temporal lobe- prosopagnosia
Tumors in the temporal love are also associated with visual and auditory hallucinations
The occipital lobe
-Primary visual cortex- receives and processes information from the visual system
-Analyses visual information- features such as light, pattern, shape ect
- damage- deficits is visual perception- eg problems in perceiving faces and objects, cortical blindness - blind because of brain not eyes
-People who go blind but have working visual cortex, will be able to imagine visual scenes and have visual dreams
Epileptic seizures
-Individuals who experience epileptic seizures can have different experiences depending upon the area of the brain affected
-Understanding the function of the different brain areas therefore can contribute to our understanding of experiences during an epileptic seizures
Epilepsy
-Neurological condition,characterised by tendency to have recurrent seizures
-5% of global population will experience a seizure but do not have epilepsy
-40-50 million people with epilepsy worldwide
-2 million new cases, globally each year
-50% of cases start in childhood
What is a seizure?
-Sudden (but often) and excessive neuronal firing
Normal firing rates 80x per second
During seizure- up to 500x per second
Often a period of extreme tiredness afterwards
Can occur in any part of the brain
Classifying seizures
Focal
Focal aware- activity while alert
Focal impaired awareness- activity changes awareness
Secondary generalised, activity in one brain area spreads
Generalised
Absence- staring
Myoclonic- short jerky movements
Tonic-clonic- go stiff,fall have convulsions
Tonic- go stiff, fall, no convulsions
Atonic- fall limply
Temporal lobe epilepsy
-Most common starting place
-Associated with visual and auditory perception
-Common symptoms
-Sight-seeing small things as large and vice versa
-Hallucinations- smells,sounds and tastes as well as visual
-Feeling detached from environment
-Deja vu
Frontal lobe epilepsy
-Predominantly deals with movement
Often brief- afterwards period of weakness
Rare- Todd’s paralysis
Common symptoms
-Head drawn to one side
Arm/hand becomes stiff and drawn upwards
Trembling in finger moves up hand and whole arm (Jacksonian seizure)
Less common symptoms
Behavioural (screaming,swearing,laughing)
Parietal lobe epilepsy
-Associated with bodily sensations
-Seizures cause strange physical sensations
-Tingling/warmth down one side of body
Parietal lobe next to frontal lobe - can experience movements (sensory seizures)
Occipital lobe epilepsy
-Associated with vision
Common symptoms
-Seeing flashes
-Seeing bells of light
-Temporary absence of vision
