Central Nervous System and Brain Lobes

• The processing core is the central nervous system.
• Bodily functions like awareness, movement, communication, thinking, and senses are managed by the brain.

Structure of the Central Nervous System

• Brain
• Spinal Cord
• Meninges

The Brain

• The components of the brain are the cerebrum, cerebellum, and brain stem.

Lobes of the Cerebral Cortex

• Frontal Lobe
• Parietal Lobe
• Temporal Lobe
• Occipital Lobe
• Frontal Lobe: controls attention, thinking, memory, reasoning, and learning.
• Parietal Lobe: primarily concerned with cutaneous sensations and their coordination with visual/auditory input.
• Parietal Lobe: helps in understanding speech, written language, and memorizing symbolic sounds/words.
• Temporal Lobe: processes auditory information.
• Occipital Lobe: interprets visual impulses, memorizes visual stimuli and helps in colour visual orientation

Brain Lobes: Sulcus Information

Central Sulcus/Fissure of Rolando:

• Separates the cortical motor area from cortical sensory area.

Lateral Sulcus/Fissure of Sylvius:

• Forms the boundary between the temporal lobe and the frontal/parietal lobes.

Parieto-occipital Sulcus:

• Provides a landmark for defining the location of the primary visual cortex.

Brodmann Areas

• Defined and numbered into 52 regions by Korbinian Brodmann
• Defined by its cytoarchitecture (histological and cellular organization)

Area 312

• Location: Postcentral gyrus
• Processes somatic sensations
• Localizes touch, temperature, vibration, and pain
• Functions in sensory perception and orofacial movement
• Motor learning occurs here
• Lesions can cause agraphesthesia and astereognosia.

Area 4

• Location: Precentral gyrus
• Functions in execution of motor movements
• Controls finger/hand/wrist and orofacial movement
• Also controls breathing and voluntary blinking
• Involved in learned motor sequences
• Lesions cause paralysis of the contralateral side of the body.

Area 5

• Location: Superior Parietal Lobe
• Functions as an area for sensory input
• Is involved in stereopsis and line bisection judgements
• Plays a role in visuomotor attention
• Lesions cause ideomotor apraxia (difficulty in moving)

Area 6

• Controls and plans movements
• Has a large role in motor skills, language, and memory functions
• Includes motor sequencing/planning, laughter/smiling, and interlimb coordination
• The "Motor Association Cortex" includes areas 6, 8, 44, and 45.
• Lesions affect sensory guidance and the control of proximal/trunk muscles. Kinetic apraxia = trouble performing soft movements

Area 9

• Area 9 is the dorsolateral/anterior prefrontal cortex (DLPFC).
• This is the highest cortical area
• Area 9 is involved in cognitive functions such as working memory, attention, and executive function.
• Also it is involved in integrating sensory and mnemonic information.
• Another part of the process is that it regulates intellectual function and action.
• Area 9 is also involved in the act of deception and lying
• Lesions in this area cause difficulties in inhibiting responses, resulting in dysexecution syndrome.

Area 10

• Similar to area 9, the anterior prefrontal cortex is the highest cortical area involved in cognitive functions such as working memory, attention, and executive function
• Has a role in integrating sensory/mnemonic information as well as regulation intellectual function/action.
• Is involved in deception and lying
• Lesions in this area have similar effect to lesions in area 9 - dysexecution syndrome.

Area 17

• Location: Occipital lobe in the back of the brain
• Interprets visual information received from the eyes
• Contains a well-defined map of spatial information for vision
• Lesions here cause partial/complete cortical blindness

Area 22

• Location: close to the external ear in the superior temporal gyrus.
• Also known as Wernicke's area
• Functions in processing sounds and comprehension of speech
• Lesions cause difficulty finding words, and semantic paraphasias
• Also causes prosopagnosia, and can cause disturbances in drawing

Area 37

• Involved in higher-level vision, such as the processing of color information, recognizing faces/bodies, and word/number recognition

Area 22/39/40

• Known as Wernicke's area
• Controls speech fluency
• Lesions cause language disorders, characterized by fluent speech paraphasias, and often the output is jumbled/nonsensical

Area 44/45

• Known as Broca's area

• Is involved in motor speech programming

• It is involved in putting together the binding elements of language,

• It Is also involved in selecting information among competing sources

• It is key in sequencing motor/expressive elements

• Also plays a role in cognitive control mechanisms for syntactic processing sentences

• And the construction of complex sentences/speech patterns

• A Lesion in this area cases a deficit in the ability to speak/produce proper words/sounds,

• Despite still maintaining comprehension and ability to formulate sentences mentally

• Spinal cord location: Continuous above the medulla oblongata

• Spinal cord function: Carries nerve signals from brain to body & back, controls body movement/functions, and reports senses to the brain while managing reflexes.

• Cervical Vertebrae (C1-C7)

• Thoracic Vertebrae (T1-T12)

• Lumbar Vertebrae (L1-L5)

• Sacrum (S1-S5)

• Area 8 cervical nerve pairs run mostly to your face and head

• Area 12 thoracic nerve pairs extend to your chest, upper back, and abdomen.

• Area 5 lumbar nerve pairs run to your legs and feet.

• Area 5 sacral nerve pairs extend into the pelvis. White matter:

• Is mainly made up of myelinated axons while gray matter is composed of neuronal cell bodies.

• Is the lighter tissue in the brain and spinal cord.

• Consists mainly of nerve fibers that extend from neurons

• Form connections between different parts of the brain and spinal cord.

• Acts like a communication network, allowing signals to travel between different areas of the nervous system.

• Colored by myelin, which is insulates the nerve fibers, and speeding up their transmission of nerve impulses.

• Gray matter:

• The darker tissue in the brain and spinal cord.

• Containing the cell bodies of neurons, which are the main information-processing cells of the nervous system.

• Involved in functions such as memory, emotions, muscle control, and sensory perception.

• Forms the outer layer of the brain (cortex) and clusters in deeper regions called nuclei.

• The brain is 40% gray matter and 60% white matter.

• Gray matter contains most of the brain's neuronal cell bodies

• White matter is made up of bundles that connect various gray matter areas.

• Gray matter fully develops once a person reaches their 20s

• It helps Sends information to various parts of the body.

• White matter develops throughout the 20's, peaking in middle age.

• White matter interprets sensory information from various parts of the body.

Meninges

• Protect the brain and spinal cord, and area three-layer membrane.
• Pia mater: inner layer; fragile
• Arachnoid mater: middle layer; web-like structure, cushions the rain.
• Dura mater: out later protective area
• Brain is 40% gray matter and 60% white matter.

Brain Meninges vs Spinal Cord Meninges

Brain Meninges:

• Protective membrane of the brain
• The dura mater is two layers, and its space is called the epidural space.

Spinal Cord Meninges:

• Is a protective membrane covering the spine.

• Its dura mater has a single meningeal layer.

• The dura mater is separated by the epidural space, containing nerve roots, intraspinal veins, and adipose tissue.

• Meninges function as a shock absorber for from brain damage and trauma.

• They also support the blood arteries.

• Dura Mater: Outer, thick, and strong.

• Arachnoid Mater: middle layer, and it does not contains any nerves or blood vessels

• Pia Mater: innermost layer contributes to the continued rigidity

Brain stem

• The midbrain, pons, and medulla oblongata make up the brain stem.
• Connects the brain to the spinal cord.
• Is responsible for basic vital life functions, i.e., breathing, heartbeat, and BP
• Directly controls breathing and blood flow

Midbrain/Mesencephalon:

• Is located below the cerebral cortex and above the brain stem.
• Relaying vision and hearing information.
• In addition to playing a role in controlling movement, pain signals, and setting the sleep / wake cycle.

Pons:

• Second lowest section just above the medulla oblongata
• Influences sleep cycle and bodie's alertness upon waking up
• Manages pain signals /sensation of pain from the neck down
• Works in coordination with other structures; specifically with balance, movement and management of breathing

Medulla Oblongata:

• Connects brain to spinal cord
• Manages heart, circulation, and breathing (HR, BP)
• Manages automatic processes such as coughing, sneezing, swallowing, vomiting, and maintaining balance

Cerebellum

• Situated behind thepons and immediately below the posteriorportion of the cerebrum

• Concerned with the coordination of voluntary muscular movement, posture and balance

• Involved in some cognitive functions such as language

• Major role in adapting and fine tuning motor programs

• Spinocerebellum: concerned with the unconscious, proprioception

• Vestibulocerebellum: maintains equilibrium

• Pontocerebellum: coordinates fine movements

• Circle of Willis: for anastomotic connections between anterior and posterior cerebral blood flow for arterial blood supply to the brain.

• Afferent Tracts: From the skin / organs to the CNS

• Efferent Tracts carry motor info from the brain to muscles