Week 1 Functional Neuroanatomy Flashcards
What are the layers of the meninges?
(Brain) Pia mater (Subarachnoid space) Arachnoid layer Dura mater (Skull)
What are the 4 (5) lobes of the brain and their basic functions?
Forebrain – neocortex
• Frontal lobes – motor executive function, memory, speech production
• Temporal lobes – auditory, speech comprehension, memory, visual perception
• Parietal lobes – somatosensory, visual perception, integration of stimuli
• Occipital lobes – vision
Insula
What are the various views of the brain?
Dorsal - from the top Ventral - from the bottom Lateral - towards the side Medial - towards the middle Superior - above/top Inferior - below/bottom Anterior - front Posterior - back
What are the four ventricles and what do they do?
Two lateral ventricles
Third ventricle
Fourth ventricle
Filled with CSF
Provides buoyancy for 1.4kg brain
Tumours can grow inside ventricles – very hard to operate – 3rd ventricle is colloid cyst - adopt wait and see approach
As passages are narrow, fluid can build up – hydrocephalus – intracranial pressure can lead to pressure on thalamus and other structures - bizarre behaviour as will begin to push on those areas ie use a shunt and example of behaving like a dog.
What is grey matter?
Cell bodies - may be organised into nuclei (outside of cortex)
What is white matter?
Axons (inside of cortex)
What are the main functions of the Medulla Oblongata & Pons?
Regulates basic functions such as heart rate, respiration, blood pressure, swallowing, eye movement
Reticular Formation: arousal & sleep/wake cycle
Where do the cranial nerves enter the brain?
Nuclei of 5-12 enter at Medulla Oblongata & Pons
Nuclei of 3 and 4 enter in tegmentum (midbrain)
What are the main functions of the Medulla Oblongata & Pons?
Regulates basic functions such as heart rate, respiration, blood pressure, swallowing, eye movement
Pons-
o Superior to medulla and anterior to cerebellum
o Main connective bridge between brain and cerebellum – point of synapse (connection between neurons) for some cranial nerves
o Control centre for eye movements and vestibular functions (balance)
o Superior olive – auditory info from ear to brain, both ears converge
Reticular Formation: arousal & sleep/wake cycle - diurnal rhythm
Damage - loss of consciousness, vegetative state, death, coma
What is the main functions of the Cerebellum?
Balance & coordination and learning of skill movements, muscle tone, cognitive and motor sequencing (esp. timing). Whole body in space rather than fine motor skills
• Sequencing as a motor program – automatic so use procedural memory ie dancing
Where is the midbrain, what are the structures of the midbrain, and their functions?
Small, superior to hindbrain (Pons)
- Tectum (roof) dorsal
- Superior colliculi (nuclei for visual function)
- Inferior colliculi (nuclei for auditory function)
- Orienting - orient to visual and auditory info – well developed in animals – combine info to locate threats/food etc
-Tegmentum (floor) ventral
*Nuclei of 3rd 4th cranial nerves (eye movement)
*Ventral TA: natural reward circuitry (motivation, social affiliation)
• high activation when doing rewarding things
• damaged with unnatural things ie substance abuse (meth and heroin) changes biological structure and reduces natural rewards like seeing family
What are the structures and functions of the diencephalon (between brain)?
Thalamus
Not passive but adds extra info and projects to relevant part of cortex, processes basic info
Comprise pairs of nuclei projecting to the cortex
Relay station for sensory signals – lateral (visual), medial (auditory) geniculate nuclei, dorsal (memory) and ventral posterior nuclei (sensory)
Hypothalamus
Regulates hormone release from the pituitary gland (HPA)
Mediates ANS function and behaviour (e.g., flight/flight, hunger and sexual drives)
Damage can alter desire for food and water ie priest who drank all the water from the vases
Where is the limbic system, what is the limbic system and what structures does it house?
Ventral/inferior to the cortex
Circuitry of midline structures that circle the thalamus:
Hypothalamus
Mammillary bodies
Cingulate gyrus (Anterior Cingulate – also part of PFC)
Hippocampus
Amygdala (almond) – primary processing of emotion (emotional significance but not response)
What is the basal ganglia and what structures does it house?
Collection of subcortical grey matter
- Caudate nucleus (striatum)
- Lentiform nucleus
- Globus pallidus (pale globe)
- Putamen (striatum)
- Substantia nigra (dopamine producing)
- Limbic: Nucleus accumbens and ventral tegmental area (dopaminergic pathways)
What is the basal ganglia and what structures does it house?
Collection of subcortical grey matter
- Caudate nucleus (striatum)
- Lentiform nucleus
- Globus pallidus (pale globe)
- Putamen (striatum)
- Substantia nigra (dopamine producing)
- Limbic: Nucleus accumbens and ventral tegmental area (dopaminergic pathways)
o Controlled and fluid movements – initiating and fine movement
o Important for voluntary control of motor function, procedural and reward learning, executive functions, emotion
What is the cerebral cortex?
- Frontal Lobes (motor, executive function, behavioural regulation, memory, speech production)
- Temporal Lobes (audition, speech comprehension, emotion, memory, visual perception)
- Parietal Lobes (somatosensory, visual perception, multi-modal integration of stimuli)
- Occipital Lobes (vision)
Insula – part of CC folded deep in lateral sulcus: consciousness, interoceptive awareness, self-awareness, emotion (contagion), body homeostasis, pain
What is the cerebral cortex?
o Bark, outer layer of brain
- Frontal Lobes (motor, executive function, behavioural regulation, memory, speech production)
- Temporal Lobes (audition, speech comprehension, emotion, memory, visual perception)
- Parietal Lobes (somatosensory, visual perception, multi-modal integration of stimuli)
- Occipital Lobes (vision)
Insula – part of CC folded deep in lateral sulcus: consciousness, interoceptive awareness, self-awareness, emotion (contagion), body homeostasis, pain
Develops during adolescence
Mindfulness training an increase
What is the visual pathway?
Eye Optic nerve Optic chiasm Optic tract Lateral geniculate nucleus Thalamus (relay station) Primary visual cortex in occipital lobe
Where does visual information get processed?
Right sides of both eyes is processed in the left PVC
Left sides of both eyes is processed in the right PVC
- Contralateral
What happens with occipital lobe damage?
Contralateral loss of visual sensation and recognition (small = scotoma; large = anopia) (LH = RF, RH = LF)
Perceptual problem: difficulties in discriminating visual objects that are different in sizes, shapes, orientations, and colours
What is visual agnosia?
inability to combine visual impression into complete patterns and interpret these
What is object agnosia? What are the two types?
Apperceptive: Inability to develop a “percept” of objects (failure to recognise objects, cannot copy, cannot match)
Associative (failure to recognise objects despite intact perception – can copy/match objects but not identify) – failure to associate visual representation with meaning
What is prosopagnosia?
inability to recognise faces
What is prosopagnosia?
Inability to recognise faces
Bilateral damage to the
occipital-temporal junction (fusiform)
Disorder is dissociable from
facial emotion recognition and
object agnosia
What are dissociations and double dissociations?
Assumptions about brain function based upon the pattern of people’s intact abilities and impairments within the same functional domain.
Person A has an impairment in word pronunciation (phonological skills) and intact understanding of word meanings (semantics) = dissociation
Person B has an impairment in semantics and intact phonological abilities
Evidence from Person A+B = double dissociation
Suggests that these abilities are subserved by different brain regions (and can be selectively damaged)
What are the areas of parietal visual area?
Tertiary area
Right: contralateral neglect, inability to consciously attend to objects in the left visual space despite intact visual pathways and cortex (spatial attentional problem) - not conscious attention
Left/bilateral – multimodal integration (temporo-parietal junction) = visual/auditory/tactile & motor
Affects reading, writing, maths and skilled movements (alexia/dyslexia, agraphia, acalculia, apraxia)
What are the three main areas of the parietal lobe for somatosensory processing?
Primary area: recognition of sensory stimuli from contralateral side of the body
Secondary area: tactile perception, touch discrimination and body sense
Tertiary area (TPJ): integration of stimuli (visual, auditory and somatosensory); guiding movement in space and spatial representation
What are tactile processing disorders?
Primary area (somatosensory strip)
- Loss or alteration of sensation of touch,
pain, temperature and body sense on
contralateral side of the body
Secondary area
- Partial or complete inability to recognise somatosensory stimuli. 2 types
Loss of ability to recognise objects by touch
Loss of knowledge or sensory awareness of one’s own body or bodily condition
What are the three hierarchical zones of motor function?
Tertiary zone: Formation of behavioural intention – prefrontal cortex
Secondary zone: Preparation and organisation of motor programmes – premotor areas of frontal lobes
Primary zone: execution of motor programmes – motor cortex (input from thalamus and basal ganglia) and spinal cord
What happens with damage to the primary motor area?
impairment of motor functioning (speed, movement and strengths) in limb and digits – extensive damage = hemiplegia - can do the major movement but not with strength
Contralateral
What happens with damage to the tertiary and secondary motor areas?
Impaired planning, selection and organisation of motor behaviour – apraxia and apathy (apathy is no ability to plan eg lack self-hygiene, inability to complete goals)
What is the auditory pathway?
Cochlear nucleus Inferior colliculus Medial geniculate (ventral) Brodmann 41 Brodmann 42, 22 (secondary) Tertiary and paralimbic
What can damage to the auditory processing areas of the temporal lobe result in?
Damage to primary, secondary and tertiary areas (41, 42, 22) of temporal lobe can lead to disorders of auditory sensation and perception
However, damage to primary area of auditory cortex (41) does not always lead to cortical deafness – more deficits in discrimination
What is amusia?
Agnosia for sounds
LH speech
RH music
What is Wernicke’s aphasia?
Damage to BA 22 of dominant hemisphere leads to Wernicke’s or receptive aphasia (deficits in language comprehension, word recognition, poor repetition)
What is Broca’s aphasia?
Damage to Brodmann’s area 44 (dominant hemisphere): Broca’s aphasia (problem with speech production)
What areas are involved in speech and language?
Broca's area Primary motor cortex Aruate fasciculus Primary auditory cortex Wernicke's area Angular gyrus Primary visual cortex
What is conduction aphasia?
Fluent speech, good comprehension, poor repetition, poor naming
What is global aphasia?
Speech is nonfluent, poor comprehension, variable aphasia, poor repitition, poor naming
What are the origins of auditory hallucinations?
Verbal hallucinations activated the primary auditory cortex, Broca’s area, and speech zone in posterior temporal cortex (LH), and limbic system
> 65% of schizophrenia
What are the three stages of Posner’s model of attention?
1) Alerting or Arousal Network (security guard – surveillance and alert) – brain stem (RAS) and parietal lobes – sustained attention or vigilance
2) Orienting Network (signal detection - brain shifts from general to specific attention) – selective attention (midbrain, parietal and Temporoparietal Junction)
3) Executive Network (signals are evaluated and a decision is made about what to do next) – Dorsolateral PFC and ACC, attentional switching and divided attention
What are the types of memory and how are they formed?
Stimulus from sensory organs PERCEPTION Sensory memory - 1 second ATTENTION Short term memory/working memory >1 minute ENCODING (consolidation/repetition) Long term memory
What are the two types of long term memory?
Declarative
Non-declarative
What are the two types of declarative memory and where is it stored?
Episodic
Semantic
Medial temporal lobe, diencephalon
What are the four types of nondeclarative memory?
Procedural memory (skills ad habits) - basal ganglia
Priming - neocortex
Simple classical conditioning (amygdala, cerebellum)
Habituation, sensitisation (reflex pathways)
What can damage to the hippocampus (medial temporal cortex) cause?
Modality specific memory problems
LH problem in learning and remembering verbal material
RH problem in learning and remembering visual material
Both Hemispheres: general amnesic syndrome
What is amnesia?
The profound inability to learn new information
What are the four types of amnesia?
Global amnesia (Clive, HM) Post-traumatic amnesia Anterograde amnesia Retrograde amnesia Psychogenic amnesia
Clive
meningitis-like symptoms (fever, headaches, fatigue and confusion), lasting several months
Finally diagnosed with HSVE and treated with an antiviral drug which saved his life “but left his brilliant mind full of holes”
CT scan – low density in the (L) temporal lobe – extending into inferior and posterior frontal lobe and ® medial temporal lobe
Damage to the limbic region which enables core consciousness but not autobiographical consciousness, thus leading to a life “being sensed but not really examined
What is Wernicke Korsakoff’s syndrome?
Degenerated diencephalon (particularly dorsomedial nucleus of the thalamus & mammillary bodies)
Slow development: difficult to pinpoint onset of amnesia
Damage often extends to frontal lobes
Lack of thiamine from excessive alcoholism
What are the functions amygdala?
Role in emotional processing and emotional learning and memory (both implicit/explicit).
- Mediates approach and withdrawal behaviour
- Fear conditioning – neutral stimuli gets paired with fearful experience and produces fear reaction (phobia and avoidance reactions) - little Albert
The amygdala interacts with the hippocampal memory system:
Responsible for assigning emotional significance to stimuli and events
Affects the storage of memories and influences recall
What are the two threat processing pathways?
1) Innate and fast-acting thalamo-amygdala pathway, bypasses cortex to elicit immediate autonomic, endocrine and behavioural response (unconscious/implicit processing)
Adv of emotion driven system: adaptive for survival, diverts attention in presence of threat and danger
Disadv of this system: can be too dominating; hasty and potentially irrational reactions that affect goals (e.g., good relationship)
2) Slow acting thalamo-cortical-amygdala pathway that supports cognitive appraisal of the meaning of stimuli within context (LeDoux, 1996) – react in accordance with goals and social needs (conscious processing through orbital prefrontal cortex)
What is the role of orbito-frontal cortex in emotion processing?
Role in regulating emotional expression and inhibition of inappropriate social behaviour
Connections with the limbic system: amygdala may elicit learnt emotional associations – while the OFC corrects/adjusts responses (down regulation) Reasoning about an emotional event can reduce its emotional impact and alter behaviour
Example of an argument in threat response
Fast-acting and non-conscious threat response system: quick analysis of emotional meaning o f of the situation.
Perceptual representations link external stimuli (e.g., comment, angry face) with internal affective and physiological states
Immediate and emotionally driven responses initially dominate or disrupt higher order goal systems (carefully thought out reactions congruent with goals and social needs).
Working memory system registers that the self is under threat and supports processing of information at the implicational level (OFC) - or what this may mean for one’s self and the future to guide goal-directed behaviour
What structures comprise the brain stem and what are their main functions?
Medulla oblongata, pons, reticular activation system
Regulate automatic body functions – breathing etc
What diseases can attack the meninges?
Meningitis (swelling) and meningioma (tumor - common in frontal lobe and often misdiagnosed as personality disorder as comes on slowly
What is CSF?
Cerebrospinal fluid - produced by choroid plexuses (0.5l a day)
CSF (clear fluid contains glucose, sodium & potassium ions, neurotransmitters, hormones, neuropetides)
Cushions the brain and spinal cord from external force, remove waste
Which cranial nerves are sensory?
o Some are pure sensory from external world to the brain
1 olfactory
2 optic
8 auditory vestibular
Which cranial nerves are motor?
3 oculomotor (eye movement) 4 trochlear (eye movement) 6 abducens (eye movement) 7 facial (movement) 11 spinal accessory (neck muscle) 12 hypoglossal (tongue muscle)
Which cranial nerves have a shared sensory and motor function?
5 trigeminal (masticatory movement)
9 glosso-pharyngeal (tongue and pharynx)
10 vagus (heart, blood vessels, viscera, larynx and pharynx movement)
• Vagus – coward punch – can kill
What are nuclei?
Clusters of cell bodies
What is excessive activity int he hypothalamus?
Anxiety and depression - emotions not regulated.
What happens when the basal ganglia is damaged/diseased?
Parkinson’s with tremors at rest and rigidity, can get frozen in movement ie running if stop because unable to initiate movement. Onset 60s/70s
Huntington’s disease – 50s onset
• Whole body twisting and violent movements
Both have depletion of dopamine
OCD in basal ganglia for repetitive and irrational behaviours, hyperactive
• In limbic system for excessive anxiety about behaviours
Interpersonal problems – fail to recognise and display emotions
What can happen with damage to the insula?
Damage – not attuned with own body, dissociative identity disorder
Depression – overactive insula – internal focus and rumination
What can happen with damage with optic nerve before optic chiasm?
Blindness in that eye
What can happen with damage with optic nerve after optic chiasm?
Blindness in either right or left visual fields in both eyes
What can happen with damage to the optic chiasm?
Can tell basic light or dark
What is Quadrantanopia?
o Quadrantanopia – opthamologist (interaction between eye and brain) to diagnose. Visual field only a quarter
How does the parietal lobe do somatosensory processing?
o Top-down and left-right processing
o Direct mapping from brain to body part- damage effects touch
o Size is relevant to number of receptors on body part ie fingers have larger part than leg.
What are the structures of the nervous system and the two main classes of cells?
o Brain, spinal cord, nerves and ganglia
o Contain two main classes of cells –
neurons (info carriers throughout body with electrical and chemical signals)
glia (support cells, 10 times more than neurons)
What are neurons?
dendritic tree -receives input from other cells
cell body – contains nucleus and other bits that manufacture proteins and enzymes
axon – appendage that carries info (can be very long or short)
o sensory neurons – info to central nervous system
o interneurons – info within CNS
o motor neurons – info from brain and spinal cord to muscles
What are glia?
not info carrying but supportive, nutritive, removes dead neurons
o maintains blood-brain barrier- tightly packed glia between blood vessels to prevent toxins entering brain
o guide neurons to position on brain from creation
What is the blood-brain barrier?
deflects toxins but also antibodies and phagocytes (white blood cells that engulf foreign bodies) unable to enter to CNS.
What does the hypothalamus do and where is it located?
with thalamus part of diencephalon)
o Controls behaviour for equilibrium ie when hungry or thirsty – to bring body back to stable state = homeostasis
o Mediates autonomic nervous system function (eg sex, hunger)
o Regulates food and drink intake – damage/lesions to dorsal and lateral regions interfere with water intake, and ventromedial damage interferes with food intake.
o Regulates body temperature – detect temperature changes in skin and blood
o Secretes hormones or stimulates other areas to secrete hormones (regulates release from pituitary gland)
Sexual behaviour, daily (diurnal) rhythms and fight/flight (lateral areas)
o Suprachiasmatic nucleus – input from retina to control hormone release to regulate diurnal rhythms
What is the thalamus and where is it located?
o Relay centre for almost all sensory info in and almost all motor info out.
Lateral (visual)
Medial (auditory)
Geniculate nuclei
Dorsal (memory)
Ventral posterior nuclei (sensory)
o Relay centre – neurons from one area of the brain synapse onto neurons that then go and synapse elsewhere in the brain. Most are also recognition centres to send out info the right part
o Lateral geniculate nucleus – info from retina via the optic tract. Low light info to the magnocellular layer and high light info to the parvocellular layer = distinguished what colour etc and then segregate info. Info is received into each layer based on where int eh retina the input was received rather than the layers being able to differentiate the light sensitivity
What are the valley’s between the gyrus (bumps) called?
sulcus, and if it’s deep is called a fissure
What are the bumps in the cortex called?
gyrus – giant sheath of neurons wrapped around other brain structures
