5b nervous system pt 2

What are the cerebral cortex, gyri and sulci?

• Cerebral cortex: the brain's outer layer

• Gyri: raised bulges or ridges

• Sulci: grooves separating gyri

• The pattern of folds gives the cortex its characteristic topography

• Slide 3.

What is the functional value of a folded cerebral cortex?

• Folding packs a much larger cortical surface area into the limited space of the skull

• More surface area allows more cortical tissue and neural processing without requiring a much larger head

• Gyri and sulci therefore increase processing capacity

• Slide 3.

Compare the major functions of the frontal and parietal lobes.

• Frontal lobe: voluntary movement through motor cortex, speech production, planning, decision-making, problem-solving and other higher-order thought

• Parietal lobe: somatosensory processing, spatial attention and awareness of the body in space

• Memory aid: FPOT orders frontal, parietal, occipital and temporal lobes

• Slide 4.

Compare the major functions of the temporal and occipital lobes.

• Temporal lobe: auditory processing, language comprehension, memory and stored knowledge

• Occipital lobe: visual processing and visual experience

• Damage produces deficits related to the affected lobe rather than a general loss of every mental ability

• Slide 4.

What does early blindness reveal about cortical plasticity?

• In congenital or very early blindness, unused occipital cortex can be recruited for nonvisual processing such as touch

• This cross-modal reorganization shows that cortical function is partly shaped by experience

• Reorganization is generally more limited when blindness occurs later in life

• Slide 4.

What do the motor and sensory homunculi represent?

• Motor homunculus: body map in frontal-lobe motor cortex controlling voluntary movement

• Sensory homunculus: body map in parietal-lobe somatosensory cortex processing bodily sensation

• Nearby body regions tend to occupy nearby cortical regions

• Slide 5.

Why are the hands, lips and face disproportionately large in cortical homunculi?

• Homunculus size represents the amount of cortex devoted to a body part, not its physical size

• Hands require fine motor control and detailed touch processing

• Lips and face have dense sensory input and precise motor demands

• More cortical space means greater neural control or sensitivity • Slide 5.

How does an ischemic stroke impair neural function, and what does FAST mean?

• A blocked blood vessel reduces blood and oxygen delivery to brain tissue

• Oxygen-deprived neurons rapidly lose function and can die

• FAST: Face drooping, Arm weakness, Speech difficulty, Time to seek emergency help

• Rapid treatment matters because time is brain

• Slide 6.

What is inter-individual cortical variability?

• Human brains share the same major lobes and general organization

• The exact shapes and locations of gyri and sulci vary across individuals

• Functional landmarks are therefore broadly consistent but not geometrically identical in every person

• Slide 7.

Distinguish gray matter from white matter and link each to neuron anatomy.

• Gray matter contains many neuronal cell bodies, dendrites, synapses and unmyelinated regions

• White matter consists mainly of bundles of myelinated axons

• In the cerebrum, gray matter forms much of the outer cortex while white matter lies deeper and connects regions

• Slide 8.

Why does myelin make white matter look white, and how is multiple sclerosis relevant?

• Myelin is lipid-rich and gives axon bundles a pale or white appearance

• It electrically insulates axons and supports fast signal transmission

• Multiple sclerosis damages central myelin, disrupting white-matter communication and producing varied neurological symptoms

• Slide 8.

What does diffusion tensor imaging reveal about white matter?

• Diffusion tensor imaging maps the direction of water diffusion along axonal bundles

• It visualizes structural pathways connecting brain regions, making white matter the brain's information highways

• Connectivity changes during development and can be altered by trauma

• Slide 9.

What are the thalamus's major functions?

• The thalamus is a central relay or switching station that routes much sensory information to appropriate cortical areas

• It also contributes to arousal and consciousness

• Damage can disrupt communication across widespread brain systems and may severely impair consciousness

• Slide 10.

Contrast the hippocampus and amygdala.

• Hippocampus: essential for forming new memories and organizing memory-related information

• Amygdala: evaluates emotional significance, especially threat and fear

• Damage can selectively impair new memory formation or emotional responding while leaving unrelated abilities more intact

• Slide 10.

What is the corpus callosum, and what happens if its communication is disrupted?

• It is a large bundle of myelinated axons connecting the left and right cerebral hemispheres

• It allows information processed on one side to be shared with the other

• Disruption can prevent normal interhemispheric integration even when each hemisphere remains functional

• Slides 10-11.

What are the basal ganglia's major functions?

• Support action selection, movement and procedural learning

• Help repeated behaviours and skills become automatic habits

• As a skill becomes well learned, performance requires less conscious monitoring, freeing other cortical resources

• Slide 12.

How are the forebrain, midbrain and hindbrain broadly distinguished?

• Forebrain includes the cerebral cortex and medial structures supporting complex cognition, sensation, emotion and memory

• Midbrain includes structures involved in movement, orienting and dopamine systems

• Hindbrain supports vital functions, arousal and coordinated movement

• Slides 4, 10 and 13-14.

What is the substantia nigra, and how is it related to Parkinson's disease?

• The substantia nigra is a midbrain structure that supplies dopamine to movement-related basal-ganglia circuits • Degeneration of its dopamine-producing neurons reduces movement control • This loss contributes to Parkinsonian symptoms such as slowed movement, rigidity and tremor • Slide 13.

What is the overall role of the hindbrain?

• It contains the pons, medulla, reticular formation and cerebellum • Together they support basic survival functions, sleep and arousal, communication between brain regions, balance and coordinated movement • Damage can therefore be immediately life-threatening even without direct cortical injury • Slide 14.

What does the pons do?

• Pons means bridge • It carries information between the cerebral cortex, cerebellum and other brain regions • It contributes to sleep, arousal and motor pathways • Severe ventral pontine damage can cause locked-in syndrome by interrupting motor output while consciousness is preserved • Slide 14.

What does the medulla do?

• Regulates vital automatic functions such as breathing, heart rate and blood pressure • These processes continue without conscious control • Major medullary damage can be fatal because it disrupts functions necessary for immediate survival • Slide 14.

What does the reticular formation do?

• A brainstem network that helps regulate arousal, alertness and the sleep-wake cycle • It supports the ability to be conscious and responsive to the environment • Severe damage can produce coma rather than merely a movement deficit • Slide 14.

What does the cerebellum do?

• Uses sensory feedback to refine or edit ongoing movement • Coordinates timing, balance, precision and smooth execution • Supports motor learning and also contributes to aspects of cognition • Damage often causes poorly coordinated movement rather than complete paralysis • Slide 14.

Distinguish locked-in syndrome from coma using the affected systems.

• Locked-in syndrome: consciousness and awareness are preserved, but severe pontine motor-pathway damage prevents most voluntary movement and speech • Coma: consciousness is lost, often because arousal systems such as the reticular formation are severely damaged • Inability to move does not by itself prove unconsciousness • Slide 14.