Exam1 Flashcards
CNS
Structures encases by bone (brain enclosed by cranium and spinal cord by vertebral column)
PNS
Ganglia and nerves that innervate skin, joints, and muscles
Parasympathetic nervous system division
Important for control of normal body functions. Rest and digest
Sympathetic nervous system division
Fight or flight. important in coping with stress
Telencephalon
cerebrum (cerebral cortex and deep nuclei like basal ganglia)
Diencephalon
thalamus and hypothalamus
Mesencehalon
midbrain (tectum and tegmentum)
Myelencephalon
medulla
Sensory or afferent fibers
Carry information toward a particular point. Afferent information travels from the PNS to the CNS
Motor or efferent fibers
Carry information away from a point. Efferent information travels from CNS to PNS.
Cuvier’s fraction
E/S where E=brain weight and S=body weight. Not the best way to represent intelligence
Encephalization
Amount of brain mass exceeding that related to an animal’s total body mass
EQ
Encephalization Quotient [cephalization factor]/[average mammalian value]
Cortical folding
In higher mammals, the surface of the cerebral cortex is folded, creating grooves (sulci) and bumps (gyri), increasing surface area of the cortex.
Neocortex in mammals
made up of 6 layers. outermost 2-5 mm contain 20 billion neurons in the human brain.
Gray matter
A generic term for a collection of neuronal cell bodies in teh CNS. When a freshly dissected brain is cut open, neurons appear gray.
Cortex
Any collection of neurons that form a thin sheet, usually at the brain’s surface. Cortex is Latin for “bark.” Example: cerebral cortex, the sheet of neurons found just under the surface of the cerebrum.
Nucleus
A clearly distinguishable mass of neurons, usually deep in teh brain (not to be confused with the nucleus of a cell). Nucleus is from teh Latin word for nut. Example: lateral geniculate nucleus, a cell group in teh brain stem that relays information from teh eye to the cerebral cortex.
Substantia
A group of related neurons deep within the brain, but usually with less distinct borders than those of nuclei. Example: substantia nigra (from the latin for black substance), a brain stem cell group involved in the control of voluntary movement.
Locus (plural: loci)
A small, well-defined group of cells. Example locus coeruleus (latin for blue spot) a brain stem cell group involved in the control of wakefulness and behavioral arousal
Ganglion (plural: ganglia)
A collection of neurons in the PNS. Ganglion is from teh Greek for knot. Example: the dorsal root ganglia, which contain teh cell bodies of sensory axons entering the spinal cord via the dorsal roots. Only one cell group in teh CNS goes by this name: the basal ganglia, which are structures lying deep within the cerebrum that control movement.
Nerve
A bundle of axons in the PNS. Only one collection of CNS axons is called a nerve: the optic nerve.
White matter:
A generic term for a collection of CNS axons. When a freshly dissected brain is cut open, axons appear white.
Tract
A collection of CNS axons having a common site of origin and a common destination. Example: corticospinal tract, which originates in teh cerebral cortex and ends in the spinal cord.
Bundle
A collection of axons that run together but do not necessarily have the same origin and destination. Example: medial forebrain bundle, which connects cells scattered within the cerebrum and brain stem.
Capsule
A collection of axons that connect the cerebrum with teh brain stem. Example: internal capsule, which connects the brain stem with the cerebral cortex
Commissure
Any collection of axons that connect one side of the brain with the other side.
Lemniscus
A tract that meanders through the brain like a ribbon. Example: medial lemniscus, which brings touch information from the spinal cord through the brain stem.
Gross features of the Cerebrum
5 Principal Grooves: Longitudinal (Saggital) fissure, Central sulcus, lateral (Sylvian) fissure, Parieto-occipital sulcus, Calcarine fisure
4 Principal Fiber tracts: corpus collosum, Internal capsule extending to corona radiata, optic radiations- geniculo-calcarine tract, anterior commissure
5 Cerebral lobes: Frontal, Parietal, Temporal, Occipital, Insula
5 Principal Grooves
Corpus Callosum
A thick band of nerve fibers that divides the cerebrum into left and right hemispheres. It connects the left and right sides fo teh brain allowing for communication between both hemispheres. The corpus callosum transfers motor, sensory, and cognitive information between the brain hemispheres.
The principal fiber tract connecting both cerebral hemispheres.
Corona Radiata
The radiating crown of projection fibers passing from teh internal capsule to every part of the cerebral cortex and also the descending fibers involved in coordinating movement (such as corticospinal tract).
Optic Radiation or geniculo-calcarine tract
The massive fanlike fiber system passing from the lateral geniculate nucleus (LGN) of the thalamus to the visual cortex.
Anterior commissure
Bundle of nerve fibers connecting both temporal lobes. Links the two cerebral hemispheres of teh brain. Interconnects the amygdalas and temporal lobes (role in memory, emotion, speech, and hearing). Plays a key role in sensation of sharp, acute pain. Contains decussating fibers from the olfactory tracts, vital for the sense of smell and chemoreception.
5 Lobes of the Cerebrum
Functions of the cerebrum: Cognitive functions and memory, special sensory, visceral sensory and motor, somatic sensory (self awareness), and motor (complex motor patterns).
Computerized Axial Tomography (CT)
X-ray beans are used to generate data that generates a digitally reconstructed image (invasive because of this radiation).
Joint Nobel Prize in Physiology and Medicine 1979 Allan M. Cormack and Godfrey N. Hounsfield.
Magnetic Resonance Imaging (MRI)
Better resolution than CT.
Electromagnetic signals emitted by hydrogen atoms in brain and signals are mapped by a computer.
Advantages over CT:
More detail (Spatial Resolution)
Does not require X-ray radiation
Brain slice image in any angle
Positron emission tomography (PET
Active neurons take up a radioactive analogue of glucose (2-deoxyglucose) and then it gets phosphorylated and trapped. 2-DG emits positrons which interact with electrons to produce photons that get detected by PET detector.
Frontal Lobe
Motor area including speech (Broca’s area), personality, behavior, emotional expression, intellectual functions, memory storage.
Lesions result in:
Expressive aphasia (impaired expression of words)
Muscle weakness or paralysis,
Abulla (apathetic, inattentive, and markedly slow to respond)
If in orbital rostral part (prefrontal area), Restless, indifferent to the implications of one’s actions, emotionally labile, vulgar, and indifferent to social nuances.
Parietal Lobe
Somatosensory area, especially from skin and muscle
Speech repition (left inferior)
Involved in abilities such as calculation, writing, taste, reading, left-right orientation, and finger recognition.
DAMAGE to left lobe can lead to:
loss of imagery and visualization of spatial relationships
Neglect of one side of body (anosognosia)
Problems in math, long reading, writing and understanding symbols.
Lesions of the anterior parietal lobe can cause difficulty recognizing objects by touch (astereognosis)
Lesions in Angluar Gyrus
Can cause dysgraphia/Agraphia (deficits in writing)
Dyscalculia/acalculia (deficits in calculating)
Left-right disorientation, and finger agnosia
(above are all symptoms of Gerstmann syndrome)
Smaller lesions lead to a spatial-manual deficit called apraxia (inability to do learned motor tasks.)
Occipital lobe
Vision and vision-related reflexes and functions such as reading, judging distances, seeing in three dimensions, etc.
Lesions lead to central blindness called Anton’s syndrome; patients become unable to recognize objects by sight and are generally unaware of their deficits. Seizures in the occipital lobe cause visual hallucinations.
Temporal Lobe
Auditory perception, spoken language comprehension (Wernicke’s area), visual memory, declarative (factual) memory, and emotion, smelling (olfactory area), taste, balance,
Lesions on right Temporal Lobe commonly lead to inability to interpret nonverbal auditory stimuli (i.e. music).
Lesions on Left Temporal Lobe interfere with the recognition, memory, and formation of language.
Patients with epileptogenic foci in the medial temporal lobe commonly have complex partial seizures.
Insula
Anterior insula: olfactory, gustatory, vicero-autonomic, and limbic function
Posterior insula; auditory-somesthetic-skeletomotor function. The insula integrates sensory and autonomic information from the viscera and also some pain and temperature, taste and balance sensations.
Also has motor functions. Commands the increase in heart rate and blood pressure at onset of exercise. other motor functions include hadn and eye movements. It plays a role in long and complex spoken language and speech articulation.
Other functions include bodily self-awareness and limbic-social emotions (empathy, compassion, disgust to smells and to the sight of contamination and mutilation.)
Lesions can cause vertigo and loss of balance (anterior insular cortex) and aphasia
Brodmann’s Cytoarchitectural Map
Area 4: Primary motor cortex (precentral gyrus)
Areas 1,2,3: Primary somatic sensory cortex (postcentral gyrus)
Area 17: Primary visual area
Area 42: Primary Auditory Area
Areas 44, 45: Broca’s Speech Area (inferior frontal gyrus)
Area 22, 39, 40: (Wernicke’s area) superior temporal gyrus auditory association area
Broca’s and Wernicke’s Areas
Lesions/tumors at Broca’s area cause expressive (Broca’s) aphasia: loss of the ability to speak or write language
Lesions/tumors at Wernicke’s area cause Wernicke’s or receptive aphasia (major impairment of language comprehension) or fluent or jargon aphasia (speech that has a natural-sounding rhythm, normal syntax, but is larely meaningless.
Wernicke’s area connects with Broca’s area via the arcuate fasciculus. It also has connections to the primary auditory cortex, evidence for its role in the comprehension of spoken words.
Hippocampus
In the medial temporal lobe
Functions: Memory (forming, storing, and retrieving), spatial navigation, limbic (connecting emotions and senses, such as smell and sound, to memories)
Claustrum
Near insular cortex
Connects with hippocampus, amygdala, and caudate and cortex (motor, premotor, auditory, visual, prefrontal)
Functions: perceptual “binding” of various sensory modalities (multisensory integration)
Amygdala
Deep within the temporal lobes, commected with hippocampus and cortex, hypothalamus and brainstem
Functions: fear (arousal response), attention, rewards, emotional memory, autonomic responses related to fear.
Lesion experiments show deficits in the ability to assess danger.
Fornix
The fornix is an arching, fibrous band of nerve fibers that extend from teh hippocampus to the mammillary body of the hypothalamus.
Limbic System
Structures that form an inner border to the cortex (limbus=belt or border)
Limbic cortex has three layers.
Main Functional Areas of the Limbic system
Main functional areas of the limbic system
Learning and memory
Emotion
Neuroendocrine funciton and autonomic activities (via hypothalamus)
Clinical conditions: epilepsy, congential csyndromes, dementias, various psychiatric disorders.
Amygdala (deep inside anterior end of each temporal lobe)-Controls behavior for each social occasion
Hippocampus (Medial border of each cerebral hemisphere) - Determines which sensory information will be committed to memory.
Mammillary body (Medial border of each cerebral hemisphere) - Perhaps helps to determine mood and degree of wakefulness.
Septum pellucidum (Midline of cerebrum anterior and superior to hypothalamus) - Perhaps helps to control temper and autonomic nervous system
Limbic cortex: Cingulate gyrus, cingulum, insula, and parahippocampal gyrus (Ring of cerebral cortex in medial part of cerebrum around deeper limbic structures) - Conscious components in the control of behavior
Important Fiber tracts in Limbic System
Fornix: the fornix is an arching, fibrous band of nerve fibers that extend from the hippocampus to the mammillary body of the hypothalamus
Stria terminalis: connects amygdala to hypothalamus, routing commands to hypothalamus and brainstem areas that control the expression of innate behaviors and associated physiological responses.
Diencephalon
Thalamus (Motor control sensory processing: gustatory, auditory, somatosensory, visual controls, sleep and wakefulness [arousal] and level of activity)
Hypothalamus (Secretes hormones [endocrine] and controls visceral functions [homeostatic] and the autonomic nervous system. HEAL: homeostatic, endocrine, autonomic, limbic)
Epithalamus (pineal body [secretion of melatonin and sleep/wake cycles])
Subthalamus or subthalamic nucleus (wedged laterally between the thalamus and the hypothalamus, modulates motor response.
Hypothalamus
Located anterior and inferior to thalamus: bisected by third ventricle. Landmarks: optic nerves and pituitary gland; below anterior commissure.
Concerned with homeostasis, endocrine, autonomic, and limbic functions. Regulates body water, energy balance and feeding, growth, reproduction, metabolism, etc.
Outputs: autonomic system (neural) this allows the hypothalamus to have ultimate control of things like blood pressure, heart rate, breathing, digestion, sweating, and all the sympathetic and parasympathetic functions. Endocrine system (hormones) hypothalamus is neurally and chemically connected to and controls the pituitary gland. Forebrain behavioral circuits (limbic system)
Inputs: Vagus nerve: blood pressure, distension of the gut. Reticular formation in brainstem: skin temperature. Optic nerve: light and darkness-used by hypothalamus to regulate eating, mating/reproduction. Internal receptors: water and salt balance, core temperature.
Hypothalamic subnuclei
