Chapter 2 Flashcards
Neuroplasticity
nervous system’s potential for physical or chemical change that enhances its adaptability to environmental change; ability to compensate for injury
Phenotypic plasticity
the individual’s capacity to develop into more than one phenotype—characteristics that can be seen or measured
Central Nervous System (CNS)
brainstem, forebrain, and spinal cord
Somatic Nervous System (SNS)
all the spinal and cranial nerves carrying sensory information to the CNS from the muscles, joints, and skin; transmits outgoing motor information→ movement
Motor innervation of all skeletal muscles
Autonomic Nervous System (ANS)
balances the body’s internal organs to “rest and digest” through the parasympathetic (calming) nerves or to “fight or flee” or engage in vigorous activity through the sympathetic (arousing) nerves
Motor innervation of smooth muscle, cardiac muscle, and glands
Afferent
incoming information
Efferent
outgoing information
Meninges
layered, protective covering of the brain. Includes the outer dura mater (tough double layer of fibrous tissue that encloses the brain and spinal cord in a lose sac), the arachnoid layer (thin sheet of delicate connective tissue that follows the brain’s contours), and the pia mater (moderately tough membrane of connective-tissue fibers that cling to the brain’s surface)
Subarachnoid space
filled with cerebrospinal fluid (CSF) from the 4th ventricle
Ipsilateral
structures that lie on the same side
Contralateral
structures that lie on opposite sides
Bilateral
structures that lie in each hemisphere
Proximal
structures that are close to one another
Distal
structures that are far from one another
Anterior
located near or toward the front of the animal or the front of the head (frontal; rostral)
Caudal
located near or toward the tail of the animal (posterior)
Coronal
cut vertically from the crown of the head down; used in reference to the plane of a brain section that reveals a frontal view
Dorsal
On or toward the back of the animal, or in reference to human brain nuclei, located above; in reference to brain sections, a viewing orientation from above
Frontal
“of the front”; in reference to brain sections, a viewing orientation from the front
Horizontal
Cut along the horizon; used in reference to the plane of a brain section that reveals a dorsal view
Inferior
located below (ventral)
Lateral
toward the side of the body or brain
Medial
toward the middle, specifically the body’s midline, in reference to brain sections, a side view of the central structures
Posterior
located near or toward the tail of the animal (caudal)
Rostral
“toward the beak” (front) of the animal (anterior; frontal)
Sagittal
cut lengthways from front to back of the skull; the plane that reveals a view into the brain from the side; a cut in the midsagittal plane divides the brain into symmetrical halves, a medial view
Superior
located above (dorsal)
Ventral
on or toward the belly or the side of the animal where the belly is located; in reference to brain nuclei, located below (inferior)
Gyri
bumps in the brain’s folded surface
Sulci
cracks in the brain’s folded surface
Fissures
very deep sulci
Cerebrospinal Fluid
a colorless solution of sodium chloride and other salts; cushions the brain so that it can move or expand slightly without pressing on the skull
Cerebral Cortex (neocortex)
part of the forebrain; made up of four lobes; the surface of the brain is a thin sheet of nerve tissue that is folded many times to fit inside the skull; regulates a host of mental activities ranging from perception to planning; comprises 80% of the human brain
Temporal Lobe
side of the brain; hearing and language and musical abilities
Frontal Lobe
performs the brain’s executive functions (decision making)
Parietal Lobe
top of skull, behind frontal lobe and above temporal lobe; parietal functions include directing our movements toward a goal or to perform a task (grasping an object), spatial issues, attention
Occipital Lobe
back of each hemisphere; visual processing begins
Brainstem
responsible for most unconscious behavior and basic physiological functions; begins where the spinal cord enters the skull and extends upward into the lower areas of the forebrain. Receives afferent nerves coming in from all of the body’s senses and it sends efferent nerves out to the spinal cord to control virtually all of the body’s movements (except the most complex movements of fingers/toes). Three regions→ hindbrain, midbrain, between brain (diencephalon); each performs more than a single task (both sensory and motor functions)
Major Cerebral Arteries
three (anterior, middle, posterior) that sent blood to the cerebrum
Stroke
blockage or break in a cerebral artery that is likely to lead to the death of the affective region; sudden appearance of neurological symptoms as a result of severely interrupted blood flow
Ischemic stroke
blood vessel is blocked (clot); can be treated acutely with a drug called tissue plasminogen activator (t-PA) that breaks up clots and allows a return of normal blood flow to an affected region
Hemorrhagic stroke
burst vessel bleeding into the brain
Gray matter
composed of cell bodies and capillary blood vessels; neurons of the gray matter function either to collect and modify information or to support its activity
White matter
composed mostly of nerve fibers with fatty coverings that produce white appearance; form the connections between cells
Ventricles
brain contains four ventricles that contain the cerebrospinal fluid; cells that line the ventricles make the cerebrospinal fluid that fills them; may play an important role in maintaining brain metabolism
Corpus callosum
band of white matter containing about 200 million nerve fibers that connects the two cerebral hemispheres to provide a route for direct communication between them; simliarly connected on both sides
Cerebral Aqueduct
runs the length of the spinal cord; the third and fourth ventricles drain into it
Neurons
carry out the brain’s major functions; aka pyramidal cell because it is shaped like a pyramid
Glial cells
modulate the neuron’s activities (ex. Insulating neurons); 10:1 ratio for glial cells to neurons; there are different shapes/kinds
Nuclei
clusters of similar cells
Axon
connect neurons; axons that run together that form nerves (outside the CNS) or a tract (inside the CNS)
Nervous System Development
young vertebrate embryo→ sheet of cells that folds into a hollow tube and develops into three regions: forebrain, midbrain, and hindbrain (located at the end of the embryonic spinal cord)
Spinal Cord
18 Inches long; Housed within spinal column made up of the vertebrae and disks; Each nerve corresponds to specific body location; Identified by exit points based on vertebrae level; Sends sensory and motor information to/from trunk and limbs; can act independently as well; Contains: dorsal roots, ventral roots, white matter (outer part), and gray matter (inner part)
Dorsal Root
a collection of dorsal fibers enter the spinal cord segment; are afferent (carry in information from the body’s sensory preceptors); sensory
Ventral Root
a collection of ventral fibers leaving the spinal cord segment; are efferent (carry information out from the spinal cord to the muscles); motor
Law of Bell and Magendie
the general principle that sensory fibers are located dorsally and motor fibers are located ventrally
Spinal Nerves
part of the SNS carry sensory information to the cord from the skin, muscles, and related structures and in turn send motor instructions to control each muscle
Spinal Reflex
automatic
Cerebellum
the relative size increases with the physical speed/dexterity of a species; looks like cauliflower; contains three subparts–reticular formation; pons; medulla; contains 50% of brain’s neurons; controls coorindated movement and is involved with thinking/language
Reticular Formation
part of brainstem; ill-defined netlike mixture of neurons (gray matter) and nerve fibers (white matter) from upper spinal cord to thalamus; Defined by physiologic characteristics of cells; Involved in tonic level of arousal, drowsiness, sleeping, coma
Pons
termination point for cranial nerves; nuclei receive inputs from the cerebellum and form a bridge from it to the rest of the brain; nuclei for respiration, swallowing, bladder control, eye movement
Medulla
continuous with spinal cord; contains substructures that control vital movements of the body; nuclei control vital functions (breathing, cardiovascular system, blood pressure)
Tectum
Part of midbrain; receives sensory information from ears and eyes; optic nerve sends a large bundle of nerve fibers to the superior colliculus and the inferior colliculus receives much of its input from auditory pathways; Colliculi process sensory information and also produce orienting movements related to sensory inputs (turning head to see source of sound)
Tegmentum
Part of midbrain; composed of many nuceli primarily with movement-related functions; several control eye movements; contains: red nucleus, substantia nigra, periacqueductal gray matter
Hypothalamus
part of the diencephalon (between brain); composed of 22 small nuclei and nerve-fiber systems that pass through it. Controls body’s production of hormones via pituitary gland; takes part of all aspects of behavior including feeding, sexual behavior, sleeping, temperature regulation, emotional behavior, hormone function, and movement
Thalamus
part of the diencephalon (between brain); contains 20-odd nuclei and is much larger than the hypothalamus; is a gateway for channeling sensory information traveling to the cerebral cortex systematically; all sensory systems send inputs to the thalamus for information integration and relay to the appropriate area in the cortex; routes may be indirect; some regions have motor functions or perform integrative tasks
Neocortex
aka cerebral cortex; part of the forebrain; newest cortex; tissue that is visible when we view the brain from the outside; primary function is to create a perceptual world and respond to that world; has six layers of gray matter atop of white matter and has distinct characteristics (different layers have different types of cells, density of cells in each layer varies; other differences in appearance relate to functions of the cortical layers in different regions; connected to all other parts of the brain; creates our reality
Limbic Cortex
part of the forebrain; oldest cortex; plays a role in controlling motivational states
Basal Ganglia
part of the forebrain; controls voluntary movement; collection of nuclei that consists of three principle structures–caudate nucleus, putamen, globus pallidus (substantia nigra & subthalamic nuclei); disorders of controlling movement (Parkinson’s & Tourette’s); not involved with actually activating the muscles to move
Limbic System
part of the forebrain; regulates emotions and behaviors that create and require memory; roles in emotion, sexual behaviors, memory, motivation; contains–amygdala, hippocampus, limbic/ cingulate cortex (in the cingulate gyrus); rewarding properties of psychoactive drugs and other potentially addictive substances
Injury to the Lobes
-occipital: deficits in processing visual information; may be able to perceive light/dark but unable to identify shape or color
-parietal: difficult to identify and locate stimulation on the skin; deficits in making arm movements or pointing
-temporal: difficulty recognizing sounds and processing complex visual information (faces)
-frontal-lobe: difficulty organizing thoughts and ongoing behavior or future planning
Hippocampus
part of the limbic system; memory, navigating space; bilateral damage=difficulty retaining new info
Cingulate Cortex
part of the limbic system; memory, navigating space;
Olfactory System
olfactory bulbs are located at the front of the brain; sense of smell; sends input to the pyriform cortex at the bottom of the brain, before progressing to the dorsal medial thalamus and then onto the frontal cortex; sensitive and plays a role in feeding and sexual behavior
Cranial Nerves
afferent functions (sensory inputs to the brain from the eyes, ears, mouth, nose) and efferent functions (control of facial muscles, tongue and eyes); some have both sensory and motor functions; 12 pairs of nerves—one set controls the right side of body, the other the left; contribute to maintaining autonomic functions by connecting the brain and internal organs and but influencing other autonomic responses (salivation)
Cranial Nerves
Spinal Nerves
(peripheral nerves) made up of sensory and motor nerves; receive information from the PNS; nerves on the left side of spinal cord control the left side of body, etc
Sympathetic Division
part of the ANS; arouses the body for action (fight or flight); activation starts in the thoracic and lumbar spinal-cord regions. Spinal cord is corrected to the autonomic control centers, which are collections of ganglia (control the internal organs). Sympathetic ganglia are located near the spinal cord, forming a chain that runs parallel to the spinal cord
Parasympathetic Division
calms the body down (rest and digest); connected through the spinal cord primarily through three cranial nerves (vagus nerve, facial nerve, oculomotor nerve); connects with ganglia near the target organs
Vagus Nerve
calms most of the internal organs
Facial Nerves
controls salivation
Oculomotor Nerves
controls pupil dilation
Excitation
increase in neuron activity
Inhibition
decrease in neuron activity
Alzheimer’s Disease
degenerative brain disease related to gaining that first appears as progressive memory loss and only much later develops into generalized dementia Al
- The nervous system produces movement within a perceptual world the brain creates
- The hallmark of nervous-system functioning is neuroplasticity
- Many of the brain’s circuits are crossed; olfactory sensation projects ipsilaterally and the cranial and spinal nerves are also connected ipsilaterally
- The central nervous system functions on multiple levels
- The brain is both symmetrical and asymmetrical
- Brain systems are organized both hierarchically and in parallel
- Sensory and motor divisions exist throughout the nervous system
- Sensory input to the brain is divided for object recognition and motor control
- Functions in the brain are both localized and distributed
- The nervous system works by juxtaposing excitation and inhibition
Dura Mater
part of the meninges; tough double layer of fibrous tissue that encloses the brain and spinal cord in a lose sac
Arachnoid Layer
Part of the meninges;thin sheet of delicate connective tissue that follows the brain’s contours
Pia Mater
Part of the meninges; moderately tough membrane of connective-tissue fibers that cling to the brain’s surface
Microglia
Type of glial cell;
Migrate to damaged areas as needed to dispose of pathogens and neuronal debris
Astrocytes
Type of glial cell;
Star shaped, metabolic regulation of microenvironment, response to brain injury
Oligodendrocytes
Type of glial cell;
Mainly in white matter, primary role is mylenation of axons
Ependymal Cells
Type of glial cell;
Form epithelium that produces CSF
Pruning
Neurons and Synapses initially over produced and development eliminates (prunes) large numbers of neurons; synaptic connections that have been strengthened are spared.
Up to 40% of neurons eliminated by adolescence and early adulthood
PNS
Sensory (afferent) division:
- Somatic Sensory
- Visceral Sensory
Motor (efferent) division
- Somatic Nervous System
- Autonomic Nervous System
- Sympathetic
- Parasympathetic
Somatic Sensory
General: touch, pain, pressure, vibration, temperature, and proprioception in skin, body wall and limbs
Special: hearing, equilibrium, vision
Visceral Sensory
General: stretch, pain, temperature, chemical charges, and irritation in viscera; nausea and hunger
Special: taste, smell
Regions of the Spinal Cord
top to bottom–> cervical, thoracic, lumbar, sacral, and coccygeal;
What are segments of the spinal cord called?
dermatome
Choroid Plexus
housed in lining of ventricles; produces enough CSF to flush system 4x a day
Foramen of Monro
empties CSF from lateral ventricles into the third ventricle
Cerebral Aqueduct
Empties CSF into the fourth vebtricle
Tectum
Part of the midbrain; roof; sensory component; consists of the inferior and superior colliculus
Tegmentum
Part of the midbrain; motor structure; floor; dorsal
Inferior Colliculus
Part of the Tectum; auditory orienting
Superior Colliculus
Part of the midbrain; visual orienting
Thalamus
relays sensory info except olfaction; major pathway for motor systems; implicated in attention
Thalamic Syndrome
Deficits in sensory and motor functions, including pain
Striatum
Caudate, putamen
Basal Ganglia Loops
Cortico-Striato-Pallido-Thalamo-Cortical loops: important in implementing thought into action; initiating involuntary movements; can potentially bypass a damaged loop; Parkinson’s
Amygdala
has cortical, thalamic, and hippocampal connections; emotional processing (fear), damage=rage/passivity
Capgras’ Syndrome
Type of delusion–believes that things in their life are impostures because of damage to the amygdala creating the appropriate emotional response to what we are seeing/hearing
Orbital Medical Cortex
has important connections with the limbic system; emotional processing of info
Frontal Lobe Damage: Problems
- Problems of startings
- Difficulties in mental & behavioral shifting
- Problems in stopping “disinhibition”
- Deficient self-awareness
- Concrete thinking
Lateralization
- Left–dominant for language (70% right handed/left hemi; 10% left handed/right hemi; 20% mixed)
- Right—spatial attention; language prosody, constructional ability
Red Nucleus
Part of tegmentum (midbrain); controls limb movements
Substantia Nigra
Part of tegmentum (midbrain); connected to the forebrain and is important in initiating movements
Periacqueductal Gray Matter
Part of tegmentum (midbrain); made up of cell bodies that surround the aqueduct joining the third and fourth ventricles—contains circuits controlling species typical behaviors (female sexual behavior) and help modulate pain via opioid drugs
