Neuroscience Quiz: Brain Functions and Areas

Learning Objectives

• Students should be able to describe the structures of the meninges.
• Students should be able to describe the flow of cerebrospinal fluid in the brain and functions of CSF.
• Students should be able to name the lobes and principal sulci of the brain.
• Students should be able to state the functions of the cerebrum.
• Students should be able to describe the position and functions of the thalamus and hypothalamus.
• Students should be able to describe the position and functions of the midbrain, pons, medulla oblongata and reticular activating system.
• Students should be able to describe the structure and functions of the cerebellum.

Recap of Nervous System (PNS)

• The peripheral nervous system(PNS) includes nerves to the face, upper limb and lower limb.
• Ganglia are also part of the PNS.

Recap of Nervous System (CNS)

• The central nervous system (CNS) includes the brain and spinal cord.
• The brain is within the cranial cavity.
• It is one of the largest organs.
• The brain connects to the spinal cord at the foramen magnum.
• The CNS consists of the brain (forebrain, hindbrain, and brain stem) and cerebellum.
• The brain has 4 main parts: cerebrum, diencephalon, brainstem, and cerebellum. -Brainstem includes midbrain, pons and medulla oblongata.

Protection of the Brain

• The brain is protected by the cranium and cranial meninges.
• The blood-brain barrier (BBB) protects brain cells from harmful substances and pathogens.
• Cerebrospinal fluid (CSF) further protects the brain from chemical and physical injury.

Meninges

• The meninges are three connective tissue layers surrounding the brain. -Dura mater (outermost) -Arachnoid mater (middle) -Pia mater (innermost)

Cerebrospinal Fluid (CSF)

• CSF circulates in the subarachnoid space, surrounding the brain and spinal cord, and cavities in the brain known as ventricles.
• CSF is a clear, colourless fluid.
• It carries oxygen, glucose and other chemicals from the blood to neurons and neuroglia.
• It removes wastes and toxic substances produced by brain and spinal cord cells.
• CSF is produced by the choroid plexuses in cerebral ventricles.
• Ependymal cells cover the choroid plexus capillaries forming CSF from blood plasma by filtration and secretion.
• CSF pressure is 120-180 mmHg2 and the cranial cavity contains 80-150 ml of CSF.

The Ventricles of the Brain

• There are four ventricles; two lateral ventricles, one third ventricle and one fourth ventricle
• Ventricles are cavities in the brain.

Flow of CSF in the Brain

• CSF flow pathway is from the lateral ventricles, through the interventricular foramen to the third ventricle, through the cerebral aqueduct to the fourth ventricle, and into the subarachnoid space, then into the superior sagittal sinus.

Functions of CSF

• Protection to CNS by acting as a shock absorber, absorbing shock in the event of blows to the head.
• Removal of waste products of brain metabolism.
• Regulates the extracellular environment of the CNS neurons.
• Transports hormones and hormone releasing factors.

Cranial Meninges

• The cranial meninges are tissue layers that envelop the brain.
• Arachnoid villi are in the space between the arachnoid and dura mater.
• Falx cerebri are in the subarachnoid space.

Blood Supply & Blood Brain Barrier

• The brain needs 20% of the body's oxygen supply.
• A 4-minute lack of oxygen can cause permanent damage.
• The brain requires continuous glucose supply.
• It is protected by the blood-brain barrier (BBB).
• Allows passage of lipid-soluble materials: oxygen, carbon dioxide, alcohol, anaesthetic agents.
• But controls entry of most harmful materials.
• Created by tight capillaries and astrocytes.

The Brain (Major Parts)

• Forebrain -Cerebrum
• Hindbrain -Cerebellum
• Brainstem -Midbrain -Pons -Medulla oblongata
• Diencephalon -Thalamus -Hypothalamus

Cerebrum

• Largest portion of the brain.
• Divisions: Right and Left Hemispheres.
• Separated by longitudinal fissure.
• Lobes include: Frontal, Parietal, Occipital, Temporal

Cerebrum (Parts)

• Cerebral cortex (outer rim of grey matter)
• Internal region of cerebral white matter
• Grey matter nuclei deep within the white matter.
• Cerebrum provides ability to read, write, speak, memorize, plan and create.
• Gyri = folds on cerebral cortex
• Fissures = deep grooves between folds
• Sulci = shallow grooves
• Longitudinal fissure: separates the cerebrum into right and left cerebral hemispheres.
• Corpus Callosum: connects the hemispheres internally.
• 4 Lobes: Frontal, Parietal, Occipital, Temporal
• Lobes are divided by fissures: Lateral sulcus, Central sulcus, and the Parieto-occipital sulcus.

Cerebrum (Major Gyri)

• Precentral gyrus: located immediately anterior to the central sulcus, contains the primary motor area of the cerebral cortex.
• Postcentral gyrus: located immediately posterior to the central sulcus, contains the primary somatosensory area of the cerebral cortex.
• Insula: the fifth part of the cerebrum, cannot be seen on the surface of the brain, lies within the lateral cerebral sulcus deep to the parietal, frontal and temporal lobes.

Limbic System

• Ring of structures on the inner border of the cerebrum and the floor of the diencephalon.
• Called the "emotional brain." Plays a primary role in the range of emotions (e.g., pain, pleasure, anger, affection).
• Control involuntary activity, related to survival and important in memory development.
• Damage to the limbic system will cause memory impairment.

Function of Cerebrum

• There are 3 main types of activities related to the cerebral cortex

1. Mental activity
2. Sensory perception
3. Initiate and control contraction of skeletal muscles (voluntary).

Functional Areas of Cerebral Cortex

I. Sensory areas: Receive sensory input → perception – The conscious awareness of sensation II. Motor areas: Initiate movements III. Association areas: Complex integration: memory, emotion, reasoning, judgment, personality traits, intelligence

Sensory Areas

i. Primary somatosensory area: Posterior to the central sulcus in the postcentral gyrus of the parietal lobe – Receive nerve impulse for touch, proprioception (joint and muscle position), pain, itching & temperature. ii. Visual area: Located in the occipital lobe – Receive visual information – Visual perception iii. Auditory (Hearing) area: Located in the temporal lobe – Receive information for sound – Auditory perception iv. Gustatory (Taste) area: Located at the base of the postcentral gyrus – Receive impulses for taste – Gustatory perception v. Olfactory (Smell) area: Located on the medial aspect of the temporal lobe – Receive impulses for smell – Olfactory perception

Motor Areas

• Located anterior to the central sulcus.
• Primary motor area: precentral gyrus- Control voluntary contractions of specific muscles.
• Broca's speech area: interacts with premotor area and primary motor area to regulate breathing and speech muscles.
• Language areas localized in the left hemisphere in 97% of persons.

Association Areas

• Consist of large areas of the occipital, parietal, temporal & frontal lobes anterior to the motor areas.
• Adjacent to sensory and motor areas, connected via association tracts.
• Integrate and interpret information.
  • Somatosensory association area: Posterior to primary somatosensory area – Integrates & interprets sensation, e.g., shape and texture
  • Wernicke's area: Left temporal & parietal lobes – Interprets meaning of speech: translate words into thoughts – The right hemisphere adds emotional content such as anger or joy, to spoken words.

Hemispheric Lateralization

• The two hemispheres are quite symmetrical but there are slight anatomical differences
• Functionally different in ways, with each one specialized in specific functions.
• This functional asymmetry is called hemispheric lateralization.
  • Left hemisphere: important for spoken and written language, numerical & scientific skills & reasoning.
  • Right hemisphere: more involved with musical & artistic awareness, spatial & pattern perception, recognition of faces and emotional content of languages.

Memory

• Memory is the process by which information is acquired through learning, also storing and retrieving information.
• Involves structural and functional changes in the brain.
  • Parts of the brain involved in memory:
    • Association areas of the frontal, parietal, occipital & temporal lobes
    • Parts of the limbic system
    • Diencephalon
• Motor skill memory also involves cerebellum and basal ganglia.

Brain Stem (Major Parts)

• Midbrain
• Pons
• Medulla Oblongata

Brain Stem: Midbrain

• Connects pons to diencephalon.
• Large tracts: cerebral peduncles.
• Nuclei include substantia nigra, red nuclei; control eye movements; superior colliculi; responses to visual stimuli; inferior colliculi; responses to auditory stimuli (e.g. sudden movement of head and body when you hear a loud noise).

Brain Stem: Pons

• Serves as a bridge connecting the medulla to midbrain and above.
• Contains ascending (sensory) and descending (motor) tracts.
• Connects the left and right sides of the cerebellum.
• Contains nuclei for voluntary movement from cerebrum to cerebellum.
• Helps control breathing.
• Cranial nerves V-VIII are attached here.

Brain Stem: Medulla Oblongata

• Most inferior part of the brainstem.
• White matter has sensory and motor tracts that connect spinal cord with other parts of the brain.
• Contains vital nuclei; cardiovascular center; regulates heart rate and blood pressure; medullary rhythmicity area; adjusts respiratory rhythm. Other nuclei control sensory and reflex motor areas e.g., swallowing, vomiting, coughing, hiccupping, and sneezing
• Cranial nerves VIII-XII are attached here

Reticular Formation

• The brain stem also contains small clusters of net-like arrangement of gray and white matter = reticular formation.
• Neurons within the reticular formation contain both ascending (sensory) and descending (motor) tracts.
• Ascending part = reticular activating system (RAS) - carries sensory pathways to cerebral cortex, helps to maintain consciousness (wakefulness); inactivation of RAS → induce sleep.
• Descending function: help regulate muscle tone

Diencephalon

• Located between the brainstem and cerebrum. -Thalamus -Subthalamus -Hypothalamus -Epithalamus

Diencephalon: Thalamus

• Major relay station for most sensory impulses to the cerebral cortex from the spinal cord and brainstem.
• Contributes to motor functions by transmitting information from the cerebellum and basal ganglia to motor areas of the cerebral cortex.
• Relays nerve impulses between different areas of the cerebrum.
• Maintenance of consciousness

Diencephalon: Hypothalamus

• Lies inferior to the thalamus.
• Controls many important body activities and maintains homeostasis. -Function - Works with the ANS regulating contraction of smooth and cardiac muscle and secretion of glands, eg: regulate heart rate, movement of food, contraction of urinary bladder. - Control of body temperature - Control of pituitary and hormone production. - Involved with feelings and behavior patterns. - Regulation of eating, drinking, fluid levels (thirst center). - Regulation of circadian rhythms, eg: pattern of sleep & awakening.

Cerebellum

• Divided into three functional sections: flocculonodular lobe; vermis; lateral lobes.
• Located posterior to the medulla and pons, inferior to the cerebrum.
• Attached to brain stem by cerebellar peduncles.
• Structure: Two cerebellar hemispheres, cerebellar cortex (gray matter), tree-like appearance (seen in sagittal section) of white matter and gray nuclei.
• Functions: i. Receives wide range of sensory input from muscles, joints, tendons, eyes, inner ears ii. Compares actual movements with intended ones; iii. Helps produce smooth, coordinated movements iv. Helps execute skilled motor activities v. Regulates posture and balance.

Clinical Application: Aging

• Rapid brain growth during the first few years of life.
  • Due to increase in size of neurons and proliferation of neuroglia.
  • Increase in development of dendritic branches and synaptic contacts
• From early adulthood through old age
  • Decline in brain mass (by the time one reaches 80, the brain weighs about 7% less)
  • Fewer synaptic contacts brain function -Some decrease in brain function (processing of information diminishes); conduction velocity decreases; voluntary motor movement slow down.

Test your knowledge on the brain's primary motor area, Broca’s and Wernicke’s speech areas, and hemispheric lateralization. This quiz covers key functions of various brain regions and their roles in cognitive processes. Ideal for students studying neuroscience or psychology.