Harder flashcards to remember

What theories/concepts did René Descartes propose about brain function?

• Fluid-mechanical theory of brain function

• Reflexive theory - reflex arc

• Dualism - distinction between the mind and the body

What is the 'law of specific nerve energies' proposed by Johannes Müller?

It describes the chain of reaction going to and from the brain

→ localisation of specific brain functions

What did Camillo Golgi (1843-1926) propose about the role of the neuron?

Proposed ‘reticular theory’ - all nerves are in an interconnected network

What is the neuron doctrine proposed by Santiago Ramón y Cajal?

It states that neurons are the basic structural and functional units of the nervous system.

What was Aristotle's view on the brain?

He believed that the heart was the source of all sensations, rather than the brain

What did Galen contribute to the understanding of the brain?

He viewed the brain as the ruling organ of the body, responsible for common sense, cognition and memory.

What significant contribution did Hippocrates make to neuroscience?

He theorised that the brain is the source of pleasure, grief, and emotions.

What is the function of orexin neurons?

Involved in maintenance of arousal and regulation of the sleep-wake cycle.

Which spinal area is involved in male sexual behaviour?

Medial preoptic area

What is the Hypothalamic-Pituitary-Adrenal (HPA) Axis?

• Hypothalamus (in the brain) – paraventricular nucleus detects stress and sends an alarm signal - secreting corticotropin- releasing hormone (CRH)

• Pituitary gland (also in the brain) – receives the alarm and releases adrenocorticotropic hormone (ACTH)

• Adrenal glands (on top of the kidneys) – release stress hormones, especially cortisol.

→ primary stress response system

Which structures does the diencephalon contain?

Thalamus and hypothalamus

Which spinal region is involved in sexual behaviour?

Lumbar region

Which hormones are associated with satiety and hunger?

Satiety - Leptin

Hunger - Ghrelin

What brain region mediates female sexual behaviour?

The ventromedial nucleus of the hypothalamus (VMH).

Outline the process of a voltage-gated potential

• Voltage-gated Na⁺ channels open → Na⁺ influx → membrane becomes more positive (depolarization).

• Na⁺ channels become refractory at the peak → the neuron is temporarily resistant to firing another action potential.

• Voltage-gated K⁺ channels open → K⁺ efflux → membrane becomes less positive (repolarization).

• Open K⁺ channels continue to allow K⁺ outflow.

• Hyperpolarisation (undershoot) occurs because K⁺ channels close slowly, causing the membrane potential to become more negative than the resting potential.

Which cranial nerve is associated with face sensation and chewing?

Trigeminal

Name all of the 12 cranial nerves

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• Olfactory

• Optic

• Oculomotor

• Trochlear

• Trigeminal

• Abducens

• Facial

• Vestibulocochlear

• Glossopharyngeal

• Vagus

• Accessory

• Hypoglossal

What is the threshold potential for an action potential to occur?

Approximately -55mV

Which cranial nerve is associated with tongue movement?

Hypoglossal

What is the resting potential of a neuron?

-70 mV

Which cranial nerve is associated with throat sensation, taste and swallowing?

Glossopharyngeal

Which cranial nerves are associated with eye movement?

Trochlear, abducens

What is meant by AP propagation?

AP propagation means the movement (transmission) of an action potential (AP) along a neuron's axon.

• An action potential occurs at one point on the axon.

• Na⁺ enters the cell, making that area more positive.

• The positive charge spreads to the adjacent section of the membrane.

• The adjacent section reaches threshold and fires a new action potential.

• This continues down the axon until the signal reaches the nerve terminal.

What is the function of the Na+/K+ ATPase pump?

• The Na⁺/K⁺ pump actively transports 3 Na⁺ out and 2 K⁺ in.

• This helps restore and maintain the ion gradients needed for the resting membrane potential and future action potentials.

• During repolarization, K⁺ generally moves out of the neuron through K⁺ channels; the pump then gradually helps restore the original ion distribution.

Which cranial nerve is associated with movement, sensation, and abdominal organs

Vagus

Which cranial nerve is associated with facial movement and taste?

Facial

Which cranial nerve is associated with smell?

Olfactory

Which cranial nerve is associated with neck movement?

Accessory

Which cranial nerve is associated with eye movement and pupil reflex?

Oculomotor

How is the left and right hemisphere involved in comprehension?

LEFT: literal meaning, vocabular, grammar

RIGHT: context, implied meaning

What is meant by transcortical sensory aphasia?

• Poor comprehension but preserved repetition

• Speech fluent, grammatically correct but meaningless

• May not be aware of difficulty

How is the left and right hemisphere involved in speech production?

LEFT: controls speech output (Broca’s area)

RIGHT: minimal role

How is the left and right hemisphere involved in prosody (tone, rhythm)?

LEFT: basic structure of speech

RIGHT: emotional tone, intonation

What is conduction aphasia characterised by?

Poor repetition, fluent with errors

What is phonagnosia? Which part of the brain is damaged?

The inability to recognise familiar voices, associated with damage to the right temporal lobe.

How is the left and right hemisphere involved in figurative language?

LEFT: limited alone

RIGHT: metaphor, sarcasm, humour

How is the left and right hemisphere involved in semantics?

LEFT - precise word meaning

RIGHT - broad, associative meaning

What does the term 'pure word deafness' refer to?

• Auditory verbal agnosia (pure word deafness)

• Rare disorder of speech recognition

• Patients cannot understand spoken words despite having normal hearing, reading, and writing abilities

• Typically caused by a disconnection rather than direct destruction of Wernicke's area itself

What is the name of the pathway connecting Broca’s and Wernicke’s area?

The arcuate fasciculus

Name the blood vessels in the brain

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• Anterior cerebral artery (ACA)

• Anterior communicating artery (AComA)

• Internal carotid artery (ICA)

• Middle cerebral artery (MCA)

• Posterior communicating artery (PComA)

• Posterior cerebral artery (PCA)

• Basilar artery

• Vertebral artery

• Anterior spinal artery

What does the pia mater do?

It clings to the surface of the brain and spinal cord, being thin and delicate. Smaller surface blood vessels are located here.

Outline the flow of cerebrospinal fluid

1. CSF is produced in the choroid plexus (a highly vascular tissue that projects into the ventricles).

2. CSF flows into the third ventricle, where additional CSF is produced.

3. CSF flows through the cerebral aqueduct to the fourth ventricle, then passes through small openings into the subarachnoid space.

4. CSF leaves the ventricles and circulates through the subarachnoid space around the CNS.

5. CSF is reabsorbed into the bloodstream through the arachnoid granulations.

What is the function and structure of the dura mater?

It is the outer layer which is thick, tough and flexible but not flexible that provides protection and stops brain displacement.

What is the role of bipolar cells in the retina?

They collate and transmit information to ganglion cells

What is the role of the striate cortex?

It is the first cortical area that receives and processes visual information coming from the eyes.

→ receives input from the LGN

What is stereopsis?

It is depth perception from retinal disparity, involving both monocular and binocular cues.

What is the role of horizontal and amacrine cells in the retina?

They are lateral neurites which influence cells close by

→ They cross-connect pathways to sharpen contrast, filter details, and detect motion before visual signals are sent to the brain

What is the role of the extra striate cortex?

It is responsible for movement perception

Name some factors associated with rods in photoreceptors

• Approximately 92 million rods in the retina

• Found mainly in the retinal periphery

• Very sensitive to low levels of light

• Provide monochromatic (black-and-white) vision; do not detect colour

• Poor visual acuity (lower sharpness, accuracy, and detail)

How many layers make up the Lateral Geniculate Nucleus (LGN)?

Organised in 6 specialised layers

Contralateral = 1, 4 and 6

Ipsilateral = 2, 3 and 5

What is the role of the V1 and V2 areas in vision?

They are part of the ventral stream of the extra striate cortex involved in form perception.

What are retinofugal projections?

The neural pathway that carries visual information away from the retina and to the brain

→ comprising the optic nerve, optic chiasm and optic tract

What is the role of ganglion cells in the retina?

They integrate information and send action potentials to the brain

What causes a negative afterimage?

Adaptation in the rate of firing of ganglion cells due to prolonged stimulation.

Which structures does the retina consist of?

• Photoreceptors

• Bipolar cells

• Ganglion cells

• Horizontal and amacrine cells

Explain what is meant by the rebound effect

If ganglion cells are excited/inhibited for a prolonged time, they will fire less/more relative to baseline activity

What does the medial superior temporal (MST) area process?

It processes optic flow across the retina.

Outline the order in which light enters the eye and to the retina

1. Cornea

2. Pupil

3. Lens (image reversed and inverted)

4. Vitreous humour (clear gel)

5. Retina

What type of information do parvocellular and magnocellular cells relay?

Parvocellular: Information about colour (red and green) and fine detail.

Magnocellular: Information about form, movement, depth and light-dark contrast.

Name some factors associated with cones in photoreceptors

• Approximately 4.6 million cones in the retina

• Found mainly in the fovea

• Less sensitive to light; function best in moderate to high levels of light

• Provide information about color (hue)

• High visual acuity (excellent focal identification, sharpness, and detail)

What is trichromatic coding?

A system where the retina contains three types of cones responsible for colour vision: red, green, and blue.

• Red (long nm)

• Green (medium nm)

• Blue (short nm)

• → they are sensitive to only certain wavelengths of light

What is the V5 or MT region responsible for?

It processes motion information and receives input from the superior colliculus.

Where are disparity sensitive neurons found? What are they?

In the dorsal stream of the extra striate cortex.

They are specialised nerve cells in the brain that respond to binocular disparity.

What is opponent-process coding?

A system where colour-sensitive ganglion cells respond to colour pairs, such as yellow-blue and red-green

Outline the process of transduction

• First step in the chain of events that eventually leads to visual perception.

• Involves a chemical called a photopigment.

• When photopigments are exposed to light, they break into their two components: opsin and retinal.

• This triggers a cascade of intracellular events that hyperpolarises the photoreceptor membrane, producing a change in membrane potential.

Outline the differences between ionotropic and metabotropic receptors

• Neurotransmitters cross the synapse and bind to receptors

• This opens ion channels → ions move in/out → changes membrane potential

Ionotropic (direct):

• Channel opens immediately when neurotransmitter binds

• Fast and short-lasting effect

Metabotropic (indirect):

• Activates G protein → second messenger → opens channels/changes cell

• Slower but longer-lasting effect

Outline the 6 stage process of synaptic transmission

1. Action potential arrives at axon terminal, triggering Ca²⁺ ions to move into the cell.

2. Calcium ions cause the migration of vesicles to the pre-synaptic membrane.

3. NT is released when vesicles fuse to the pre-synaptic membrane.

4. NT binds to and activates postsynaptic receptors after diffusion across the synaptic cleft.

5. NT binds to receptor sites on the post-synaptic membrane; specific NTs bind with specific receptors.

6. The binding opens NT-dependent ion channels, which change the excitability of the post-synaptic cell.

What is myasthenia gravis?

A rare autoimmune neuromuscular junction disorder causing muscle weakness and difficulties in various functions.

What is impedance matching in the middle ear?

Middle ear boosts sound pressure to transfer acoustic energy from the air to the fluid-filled inner ear without losing it to reflection

→ increases efficiency of sound transfer to the cochlear

What is the function of the vestibular system?

Maintains balance and head position, and stabilises eye movements.

Name and explain the 4 touch receptors

1. Merkel disks: detecting pressure

2. Ruffini corpuscles: maintaining grip

3. Meissner’s corpuscles: detecting surface roughness

4. Pacinian corpuscles: discrimination of fine surface textures or moving stimuli

What are the 3 regions in the auditory cortex

• Core region – contains the primary auditory cortex

• Belt region – first level of auditory association cortex

• Parabelt region – highest level of auditory association cortex

Which pathway mediates pain sensation?

The spinothalamic pathway.

What makes up the receptive organ in the cochlear?

• Basilar membrane

• Hair cells (stereocilia)

• Tectorial membrane

What are the two types of coding for pitch perception?

Place coding: Different neurons fire depending on the location on the basilar membrane.

Rate (temporal) coding: Information is carried by the timing (rate) of the action potentials fired.

What is meant by ‘lever effect’ in the middle ear?

Ossicles act as a lever, amplifying the force exerted on the tympanic membrane

Which pathway in the somatosensory system is responsible for proprioception and tactile sensation?

Dorsal column-medial lemniscus pathways

What is meant by ‘area effect’ in the middle ear?

Greater pressure is exerted at the oval window than at the tympanic membrane

Outline the structure and function of the Medulla oblongata (myelencephalon)

• Most caudal portion of brain stem

• Terminal of brain stem

→ regulates vital autonomic functions like breathing and heart rate, serves as a major signal conduit, and houses several cranial nerve nuclei

What is the function of the basal ganglia?

Involved in the control of movement and communication with the cerebellum and somatosensory cortex

→ returns info to motor cortex via thalamus

Name and outline the 3 sub-regions of the telencephalon

1. Cerebral cortex: thin outer layer of neural tissue, responsible for many 'higher-order' functions

2. Limbic system: interconnected nuclei and cortical structures located in telencephalon and diencephalon important for olfaction (smell), emotions, learning and memory

3. Basal ganglia: group of nuclei located beneath cortical surface vital for movement

Outline the structures within the limbic system

• Amygdala

• Hippocampus

• Cingulate gyrus

What is the hypothalamus responsible for?

Controls many autonomic functions of the PNS and connects the endocrine system to the nervous system

What is the function of the thalamus?

Acts as a relay station for sensory information and is involved in sleep, arousal and motor control.

What is the mammillary body?

A part of the hypothalamus involved in memory processing.

Outline the differences between the grey and white matter in the brain

Grey matter: outer layer composed of cell bodies, dendrites and glia

White matter: inner layer composed of myelinated axons

Outline the structure and function of pons (metacephalon)

Connection between cerebrum and cerebellum

→ helps coordinate movement

Outline the structure and function of the midbrain (mesencephalon)

• Made up of: tectum and tegmentum

• Tectum → Dorsal auditory and visual system

• Tegmentum → Rostral end of reticular formation

• Sleep, arousal, muscle tone, movement and vital reflexes - posture etc

Explain what is meant by ‘reticular formation’. What does it regulate?

A complex, net-like web of interconnected neurons located throughout the brainstem

→ receives and integrates input from all regions of CNS: serve as a major integration and relay centre for many vital brain systems to coordinate functions necessary for survival

Regulates muscle tone, (semi)automatic responses, posture, and locomotion.

Outline the location and functions of the diencephalon

• Division of the forebrain

• Located between the telencephalon and mesencephalon (midbrain)

• Surrounds the third ventricle

• Two main structures: thalamus and hypothalamus

Functions

• Relays sensory information (thalamus)

• Controls many autonomic functions of the PNS and connects the endocrine system to the nervous system (hypothalamus)

• Involved in emotions and memory alongside the limbic system (hypothalamus)

What is the function of the supplementary motor area (SMA)?

It is involved in the learning and planning of sequences of movements.

Name the 2 parts of the frontal association cortex

Supplementary motor area (SMA)

Premotor cortex (PMA)

What 3 tracts are lateral pathways composed of?

Lateral corticospinal tract

Corticobulbar tract

Rubrospinal tract

What is the pre-supplementary motor area associated with?

• Pre-SMA is associated with the (perception of) control of spontaneous movement

What do ventromedial pathways control?

Automatic movements of proximal and axial muscles, related to posture and locomotion.

What is the basal ganglia part of and responsible for?

• Part of telencephalon

• The control of voluntary movement.

What do Golgi tendon organs monitor and do?

• Located at the junction of muscle and tendon

• Innervated 1b sensory axons

• Monitors muscle tension (tendon stretch)

• → muscle inhibition

What do lateral pathways control?

Voluntary independent movement of distal muscles, e.g. hand, finger, forearm

What are the components of ventromedial pathways?

Ventral corticospinal tract, vestibulospinal tract, tectospinal tract, and reticulospinal tract.

What is histological staining?

Interactions between charged dyes and cells to visualise cell and tissue structure - not specific proteins/molecules

→ adding colour to thin slices of biological tissue so they can be easily seen and studied under a microscope