Central Nervous System (CNS): Brain and Spinal Cord Biology 211 A&P 1 Tony Serino, Ph.D. Biology Dept. Misericordia University

Central Nervous System (CNS) Gray vs. White matter Protection of CNS –Meninges –CSF flow Brain –Development –Selected structures Spinal cord –Selected structures

CNS (Central Nervous System) Brian and spinal cord Displays gray and white matter –Gray matter are areas of CNS with many cell bodies of neurons present (little myelinated nerve fibers) –White matter are area of CNS with few cell bodies but many myelinated nerve fibers Protected by bone and membranes

Gray and White Matter Since the cerebrum and cerebellum outgrow their cores, gray matter ends up on outside of both structures.

Meninges Dura Mater –outermost; tough, fibrous CT –In brain, divided into two layers (periosteal and meningeal) –In spine, only one layer with fat filled space above the layer called the epidural space Arachnoid –middle; web-like appearance –Potential space between Dura and arachnoid is the subdural space Pia Mater –innermost, delicate membrane fused with CNS surface –Space between Pia and Arachnoid is the subarachnoid space

Meninges of the Spinal Cord Pia mater Arachnoid Dura mater Meninges Centrum Epidural space Subdural space Subarachnoid space Dorsal Root Ganglion

Brain Meninges

Extensions of Dura Mater hold brain in cavity

Brain Ventricles

Choroid Plexus

CSF (cerebral-spinal fluid) Flow

Hydrocephalus Blockage of CSF flow can lead to severe brain and/or head enlargement. In an adult, such swelling would be fatal.

Brain Damage due to Pressure Hematoma

Brain Development Structures Functional Areas

Neural Tube Formation

Brain Vesicles

Flexures and Cerebral Cortex Growth

Major Divisions of Brain Brain Stem = midbrain + pons + medulla

Brain Anatomy (req’d)

Projections vs. Commissures

Functional Anatomy of Brain

Functional Areas of Cerebrum

Communication Note difference in hearing vs. speaking words Male vs. Female processing during a language task

The electroencephalograph (EEG) is the printout of an electronic device that uses scalp electrodes to monitor the internal neural activity in the brain cortex. Electroencephalography (EEG)

EEGs provide diagnostic information about the location of abnormal activity in the brain, such as shown in this record typical of a patient undergoing an epileptic seizure. EEG as Clinical Tool EEGs record largely the surface electrical activity of underlying brain areas Activity largely due to summated graded potentials of many neurons Amplitude shows how much activity (degree of summation and/or number of neurons)

Primary Motor and Somatosensory Gyri

Basal Nuclei: cerebral nuclei Putamen and Globus Pallidus Subthalamic nuclei and the Substantia nigra are usually included

RAS (Reticular Activating System) Brainstem nuclei intermingled with bundles of axons Receives and integrates input from all regions of CNS Involved in motor function, cardiac and respiratory control, attention, vasomotor control, sleep/wakefulness Extends along length of brain stem; used in maintaining alertness while awake

RAS receives inputs from eye, ear and general sensation to maintain alertness

Sleep Patterns NREM Stage 1  4: decreasing eye and skeletal muscle movement, increased threshold for arousal, increase size but decrease freq. of EEG REM: EEG freq. increases with less amplitude (alpha like), increase HR, Resp. Rate, and eye movement, but still in deep sleep, high oxygen consumption in brain; dream sleep 4-5 cycles of NREM/REM sleep each night (every ~90 min)

Importance of Sleep Slow wave sleep is thought to be restorative to brain function (Children have more total sleep time and are in stage 4 more than adults); Elderly have about the same total sleep time as adults but broken into smaller episodes, also spend less time in REM. Time spent in Stage 4 declines with age. Person consistently deprived of REM may become moody or depressed; may exhibit other personality disorders

Coma & Brain Death Coma is a severe loss in mental function due to brain damage; sustained loss of arousal (even with heavy stimuli), behavior response is lost, no sleep/wake cycles Persistent Vegetative State –sleep/wake cycles are present; no sign of external awareness

Limbic System: functional system; responsible for emotion and memory Cingulate Gyrus Fornix Mammillary body

Learning & Memory Declarative memory –retention of conscious experience, facts, etc.; uses Limbic system & cortex (amygdala, hippocampus & thalamus) Procedural memory –knowledge of how to do something (skilled behaviors); uses sensory cortex, basal nuclei, & cerebellum Learning –acquisition and utilization of information from past experience Memory –relatively permanent storage of information

Memory Processing Automatic long term memory linked to noxious stimuli. Many long term memories may be unretrievable consciously, but may still exist within the brain ??

Spinal Cord Receives and generates signals to body through the spinal nerves

Spinal Cord (X.S.)

Cord in Spinal Canal Dorsal Root Ganglion Denticulate Ligament Posterior Median Sulcus Posterior Root Anterior Root Spinal Nerve

Spinal Cord Segments 4 segments: Cervical, Thoracic, Lumbar, and Sacral (only 1 coccygeal nerve) 31 pairs of spinal nerves

Cervical Segment

Thoracic Segment

Lumbar Segment

Sacral Segment

Cauda Equina

Lumbar Puncture

Functional Arrangement of SC