Topic 3: Anatomy and Research Methods Part 1 PDF

3. Anatomy and Research Methods Part 1 Structure of the Vertebrate Nervous System Terminology to Describe the Nervous System Central nervous system (CNS): the brain and the spinal cord Peripheral nervous system (PNS): connects the brain and spinal cord to the rest...

3. Anatomy and Research Methods Part 1 Structure of the Vertebrate Nervous System Terminology to Describe the Nervous System Central nervous system (CNS): the brain and the spinal cord Peripheral nervous system (PNS): connects the brain and spinal cord to the rest of the body Anatomical Directions in the Nervous System Term Definition Dorsal Toward the back, away from the ventral (stomach) side. The top of the human brain is considered dorsal because it has that position in four-legged animals. Ventral Toward the stomach, away from the dorsal (back) side Anterior Toward the front end Posterior Toward the rear end Superior Above another part Inferior Below another part Lateral Toward the side, away from the midline Medial Toward the midline, away from the side Proximal Located close (approximate) to the point of origin or attachment Distal Located more distant from the point of origin or attachment Ipsilateral On the same side of the body (e.g., two parts on the left or two on the right) Contralateral On the opposite side of the body (one on the left and one on the right) Coronal plane (or A plane that shows brain structures as seen from the front frontal plane) Sagittal plane A plane that shows brain structures as seen from the side Horizontal plane (or A plane that shows brain structures as seen from above transverse plane) Anatomical Terms Referring to Parts of the Nervous System Table 3.2 Terms Referring to Parts of the Nervous System Term Definition Lamina A row or layer of cell bodies separated from other cell bodies by a layer of axons and dendrites Column A set of cells perpendicular to the surface of the cortex, with similar properties Tract A set of axons within the CNS, also known as a projection. If axons extend from cell bodies in structure A to synapses onto B, we say that the fibers “project” from A onto B. Nerve A set of axons in the periphery, either from the CNS to a muscle or gland or from a sensory organ to the CNS Nucleus A cluster of neuron cell bodies within the CNS Ganglion A cluster of neuron cell bodies, usually outside the CNS (as in the sympathetic nervous system) Gyrus (pl.: gyri) A protuberance on the surface of the brain Sulcus (pl.: sulci) A fold or groove that separates one gyrus from another Fissure A long, deep sulcus The Spinal Cord Part of the CNS found within the spinal column Communicates with the sense organs and muscles, except those of the head Cell bodies of the sensory neurons are located in clusters of neurons outside the spinal cord Consists of two types of matter Gray matter: located in the center of the spinal cord and is densely packed with cell bodies and dendrites White matter: composed mostly of myelinated axons that carries information from the gray matter to the brain or other areas of the spinal cord Photo of a Cross-Section Through the Spinal Cord Gray Matter and White Matter The brain Views of the Brain The Autonomic Nervous System Sends and receives messages to regulate the automatic behaviors of the body (heart rate, blood pressure, respiration, digestion, etc.) Divided into two subsystems The sympathetic nervous system - A network of nerves that prepares the organs for rigorous activity: increases heart rate, blood pressure, respiration, and so on (“fight or flight” response). The parasympathetic nervous system - Decreases functions increased by the sympathetic nervous system; dominant during our relaxed states Major Divisions of the Vertebrate Brain Area Also Known as Major Structures Forebrain Prosencephalon (“forward-brain”) Diencephalon (“between-brain”) Thalamus, hypothalamus Telencephalon (“end-brain”) Cerebral cortex, hippocampus, basal ganglia Midbrain Mesencephalon (“middle-brain”) Tectum, tegmentum, superior colliculus, inferior colliculus, substantia nigra Hindbrain Rhombencephalon (literally, “parallelogram-brain”) Medulla, pons, cerebellum The Brainstem: Hindbrain and midbrain Brainstem: located at bottom of the brain and is made up of the hindbrain and midbrain Hindbrain structures (except cerebellum), the midbrain, and other central structures of the Midbrain brain combine and make up the brain stem. Hindbrain: Medulla, Pons, Cerebellum Located at the posterior portion of the brain Midbrain: middle part of the brain Hindbrain The Hindbrain Medulla: Located just above the spinal cord; like an enlarged extension of the spinal cord Responsible for vital reflexes such as breathing, heart rate, vomiting, salivation, coughing, and sneezing Pons: Lies on each side of the medulla (ventral and anterior) Axons from each half of the brain cross to the opposite side of the spinal cord; the left hemisphere controls the muscles of the right side of the body and the right hemisphere controls the left side. Cerebellum: Structure located in the hindbrain with many deep folds Helps regulate motor movement, balance, and coordination Also important for shifting attention between auditory and visual stimuli The Medulla and the Cranial Nerves The cranial nerves Allow the medulla to control sensations from the head, muscle movements in the head, and many parasympathetic outputs The Cranial Nerves Table 3.4 The Cranial Nerves Number and Name Major Functions I. Olfactory Smell II. Optic Vision III. Oculomotor Control of eye movements; pupil constriction IV. Trochlear Control of eye movements V. Trigeminal Skin sensations from most of the face; control of jaw muscles for chewing and swallowing VI. Abducens Control of eye movements VII. Facial Taste from the anterior two-thirds of the tongue; control of facial expressions, crying, salivation, and dilation of the head’s blood vessels VIII. Statoacoustic Hearing; equilibrium IX. Glossopharyngeal Taste and other sensations from throat and posterior one-third of the tongue; control of swallowing, salivation, and throat movements during speech X. Vagus Sensations from neck and thorax; control of throat, esophagus, and larynx; parasympathetic nerves to control stomach, intestines, and other organs XI. Accessory Control of neck and shoulder movements XII. Hypoglossal Control of muscles of the tongue The Forebrain The most anterior and prominent part of the mammalian brain, with two cerebral hemispheres Consists of the outer cortex and subcortical regions Outer portion is known as the “cerebral cortex.” Each side receives sensory information and controls motor movement from the opposite (contralateral) side of the body. The Forebrain—The Limbic System Consists of a number of other interlinked structures that form a border around the brainstem Includes the olfactory bulb, hypothalamus, hippocampus, amygdala, and cingulate gyrus of the cerebral cortex Associated with motivation emotions, such as eating, Video camera with solid fill drinking, sexual activity, anxiety, and aggression The Forebrain—Subcortical Regions Thalamus: relay station from the sensory organs; main source of input to the cortex Hypothalamus: small area near the base Conveys messages to the pituitary gland to alter the release of hormones Associated with behaviors such as eating, drinking, sexual behavior, and other motivated behaviors Video camera with solid fill Video camera with solid fill The thalamus and the hypothalamus together form the “diencephalon.” The Forebrain—Subcortical Regions Pituitary gland: hormone-producing gland found at the base of the hypothalamus Basal ganglia: comprises the caudate nucleus, the putamen, and the globus pallidus Associated with planning of motor movement, and with aspects of memory and emotional expression Video camera with solid fill They are critical for gradual learning of skills and habits. The Forebrain—Subcortical Regions Pituitary gland: hormone-producing gland found at the base of the hypothalamus Basal ganglia: comprises the caudate nucleus, the putamen, and the globus pallidus Associated with planning of motor movement, and with aspects of memory and emotional expression They are critical for gradual learning of skills and habits. The Forebrain—The Hippocampus A large structure located between the thalamus and cerebral cortex Toward the posterior portion of the forebrain Critical for certain types of memory, especially memories for individual events Video camera with solid fill The Ventricles Four fluid-filled cavities within the brain’s central canal containing cerebrospinal fluid Cerebrospinal fluid (CSF): a clear fluid found in the brain and spinal cord Provides “cushioning” for the brain Reservoir of hormones and nutrition for the brain and spinal cord The Meninges Membranes that surround the brain and spinal cord Contain pain receptors Meningitis—inflammation of the meninges—is painful. Swollen blood vessels in the meninges are the cause of migraine headaches. Practice with a partner notegpt.io/share/61d05619 Cerebral Cortex The Cerebral Cortex The most prominent part of the mammalian brain Consists of the cellular layers on the outer surface of the cerebral hemispheres Divided into two halves Joined by two bundles of axons called the corpus callosum and the anterior commissure More highly developed in humans than other species The Cerebral Cortex Contains up to six distinct laminae (layers) that are parallel to the surface of the cortex Cells of the cortex are also divided into columns that lie perpendicular to the laminae. The Four Lobes of the Cerebral Cortex Occipital lobe Parietal lobe Temporal lobe Frontal lobe Areas of the Human Cerebral Cortex Functional areas The Occipital Lobe Located at the posterior end of the cortex Known as the striate cortex or the primary visual cortex Highly responsible for visual input The primary visual cortex (V1) focuses on basic feature extraction—it takes raw visual input and processes simple elements like edges, motion, and contrast. The visual association area is concerned with higher-order processing—it interprets, integrates, and gives meaning to the visual information (like recognizing objects, understanding movement, and associating visual stimuli with memory). The Occipital Lobe Located at the posterior end of the cortex Known as the striate cortex or the primary visual cortex Highly responsible for visual input Primary visual cortex Visual association area Light and dark contrast Object recognition: Identifying what objects are (e.g., recognizing faces, cars, Orientation of edges etc.). Color (in some areas) Depth perception: Understanding the three-dimensional structure of objects Motion (in some areas) and their spatial relationships. Basic spatial properties (such as location Motion perception: Detecting and interpreting movement in the visual field of objects in the visual field) (often processed in areas like V5/MT). Color processing: Further interpretation of color and its context (processed in areas like V4). Facial recognition: Specialized processing in the temporal lobe, such as in the fusiform face area, for identifying faces. Visual memory: Storing and recalling past visual experiences and information. The Parietal Lobe Contains the postcentral gyrus (“primary somatosensory cortex”) Primary target for touch sensations and information from muscle-stretch receptors and joint receptors Also responsible for processing and integrating information about eye, head, and body positions from information sent from muscles and joints Essential for spatial information as well as numerical information Example: using one’s fingers to count represents an overlap of spatial and numerical tasks Approximate Representation of Sensory and Motor Information in the Cortex The Temporal Lobe Located on the lateral portion of each hemisphere near the temples The primary auditory cortex is responsible for the initial, raw processing of sound features (pitch, loudness, etc.). The auditory association areas are involved in the higher- order processing of sound, helping us understand, interpret, and recognize auditory stimuli (such as language, music, or environmental sounds). The Temporal Lobe Located on the lateral portion of each hemisphere near the temples Primary auditory cortext Auditory association area Pitch: The frequency of the sound waves. Speech comprehension: Volume: The amplitude or loudness of the It helps us understand language by processing and interpreting the sound. meaning of words and sentences (in Wernicke's area, for example) Timbre: The quality or color of the sound.Sound recognition: Identifying and distinguishing between different (distinguishing between different sounds, like recognizing a dog barking or hearing a specific song. instruments or voices). Auditory memory: Storing and recalling sounds we've heard before. Rhythm: The timing of sounds Music processing: Interpreting melodies, rhythms, and harmonies. The Frontal Lobe Contains the prefrontal cortex and the precentral gyrus Precentral gyrus: also known as the primary motor cortex; responsible for the control of fine motor movement Prefrontal cortex: the integration center for all sensory information and other areas of the cortex (most anterior portion of the frontal lobe) Several areas in the prefrontal cortex and the temporoparietal junction have come to be known as the default network.  Speech Feature Wernicke’s Area Broca’s Area Posterior part of the superior Posterior part of the frontal gyrus Location temporal gyrus (left hemisphere) Language comprehension Language production (speech Function (understanding meaning) formation and syntax) Wernicke’s aphasia: Fluent but Broca’s aphasia: Difficulty speaking; Damage Result nonsensical speech; difficulty comprehension intact but speech is understanding language non-fluent or fragmented Speech Fluent speech, but often Non-fluent speech with difficulty in Characteristics meaningless or incoherent forming complete sentences Species Differences in Prefrontal Cortex The Prefrontal Cortex Responsible for: Higher functions such as abstract thinking and planning Our ability to remember recent events and information (“working memory”) People with damage to the prefrontal cortex exhibit delayed-response task. Respond to something they see or hear after a delay The anterior zone of the prefrontal cortex is important for making decisions, evaluating which of several courses of action is likely to achieve the best outcome. Prefrontal Lobotomy Surgical disconnection of the prefrontal cortex from the rest of the brain In the 1940s and 1950s, about 40,000 performed Mostly, schizophrenics, but later others with less severe mental illness Patients left with apathy, lack of ability to plan, memory disorders, and lack of emotional expression Beyond Gray Matter: The Connections The Human Connectome Project is an effort to map all the long-distance connections, analogous to the way the human genome project mapped all the genes on the chromosomes. Researchers have already demonstrated many correlations between brain connections and behavioral tendencies. Parts of the cerebral cortex do not work independently of each other. All areas of the brain communicate with each other, but no single central processor exists that puts it all together. Research one of the following and answer these questions: 1. Which behaviours or functions are affected if this is damaged? 2. Which neurological or psychological disorders can arise if this is affected? 3. Summarize the findings of a recent research article that highlights a newly found function of the structure (2016 onwards) or a case study about someone that was affected by damage or recovery of this structure. You will share with the class by uploading to the discussions section. Brainstem, thalamus, hypothalamus, pituitary gland, basal ganglia, hippocampus, meninges, ventricles, prefrontal cortex, primary visual cortex, visual association area, primary auditory cortex, auditory association area, Broca’s area, Wernicke’s area The Binding Problem Refers to how the visual, auditory, and other areas of the brain produce a perception of a single object Perhaps the brain binds activity in different areas when they produce synchronous waves of activity. For binding to occur: A person perceives two sensations as happening at the same time and in the same place. Example: A ventriloquist uses the visual stimulus to alter the response of the auditory cortex. Where Am I? As someone stroked the person’s back, a video camera relayed the information so the person could view it, appearing to be a few feet ahead. After a few minutes, the person felt as if the body were in fact a few feet ahead of where it was. From “Video ergo sum: Manipulating bodily self-consciousness,” by B. Lenggenhager, T. Tadi, T. Metzinger, and O. Blanke, 2007, Science, 317, pp. 1096–1099. An Illusion to Demonstrate Binding Clench and unclench both hands while looking at your right hand and its reflection in the mirror. Keep your left hand out of sight. After a couple of minutes, you may start to experience the hand in the mirror as being your own left hand.