Lecture 4 Anatomy PDF

PSY1617 BILOGICAL PSYCHOLOGY 1 Anatomy of the Nervous System Dr Massimo Pierucci  Structure of the Vertebrate Nervous System Central nervous system (CNS): the brain and the spinal cord Peripheral nervous system (PNS): connects the brain and spinal cord to the r...

PSY1617 BILOGICAL PSYCHOLOGY 1 Anatomy of the Nervous System Dr Massimo Pierucci  Structure of the Vertebrate 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 – Somatic nervous system: consists of axons conveying messages from the sense organs to the CNS and from the CNS to the muscles – Autonomic nervous system: controls the heart, intestines, and other organs Find Your Way Around the Brain  Anatomical Terms Referring to Directions Term Definition Dorsal Toward the back, away from the ventral (stomach) side. The top of the 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 (eg., 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 frontal plane) A plane that shows brain structures as seen from the front Sagittal plane A plane that shows brain structures as seen from the side Horizontal plane (or transverse plane) A plane that shows brain structures as seen from above Anatomical Terms Referring to Directions 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 (pi.: gyri) A protuberance on the surface of the brain Sulcus (pi.: sulci) A fold or groove that separates one gyrus from another Fissure A long, deep sulcus  Afferent vs Efferent Projections Efferent Projections Afferent Projections  Functions of the Nervous System 1. Sensory Input: Conduction of signals from sensory organs (eyes, ears, nose, skin, etc.) to information processing centers (brain and spinal cord). 2. Integration: Interpretation of sensory signals and development of a response. Occurs in brain and spinal cord. 3. Motor Output: Conduction of signals from brain or spinal cord to effector organs (muscles or glands). Controls the activity of muscles and glands, and allows the animal to respond to its environment. Nervous System Processes and Responds to Sensory Input THE BRAIN The Brain’s Skull  The Meninges The connective tissue covering on the brain and spinal cord, within the dorsal cavity, are called meninges. They provide protection for these vital structures.  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  The Meninges Cerebro-Spinal Fluid  The Meninges Cerebro-Spinal Fluid The Meninges Meningitis and Encephalitis When harmful viruses or microorganisms, such as bacteria, fungi, and protozoa, invade and multiply in the layers of the meninges, particularly the pia mater and the arachnoid layer, as well as the CSF flowing between them, this leads to meningitis (literally ―inflammation of the meninges‖). In response to the infection, the body produces white blood cells designed to attack and consume these invaders. This inflammatory response increases the pressure within the cranium, which in turn affects the functioning of the brain. Unrelieved cranial pressure can lead to delirium and, if the infection progresses, to drowsiness, stupor, coma, and even death. Usually the earliest symptom of meningitis is severe headache and a stiff neck (cervical rigidity). Head retraction (tilting the head backward) is an extreme form of cervical rigidity. Convulsions, a common symptom in children, indicate that the inflammation is affecting the brain. Meningitis is treated with antibiotics when the cause is microorganisms and sometimes with antiviral drugs for viral infections. Survivors of meningitis can have long-term consequences, such as deafness, epilepsy, hydrocephalus, and cognitive deficits. Infection of the brain itself is called encephalitis (inflammation of the brain). Like meningitis, encephalitis is caused by a number of different invading viruses or microorganisms. Different forms of encephalitis may have different effects on the brain. For example, Rasmussen encephalitis attacks one cerebral hemisphere in children. In most cases, the only effective treatment is radical: hemispherectomy, surgical removal of the entire affected hemisphere. Surprisingly, some young children who lose a hemisphere adapt rather well. They may even complete college, literally with half a brain. But intellectual disabilities are a more common outcome of hemispherectomy as a result of encephalitis. Vaccinations have been proven highly effective as protection against certain types of Pus, consisting of dead white blood cells, encephalitis, although many vulnerable populations are still not being vaccinated. bacteria with tissue debris, and serum, is Experts estimate that encephalitis affected 4.3 million people and resulted in 150,000 visible over the surface of this brain infected deaths worldwide in 2015 (GBD 2015 Mortality and Causes of Death Collaborators, with meningitis 2016).  The Brain Surface The Human brain is convoluted. Walnut-like appearance in humans and primates, with grooves, furrows (sulci) dividing convolutions (gyri). During development the cerebrum grows faster then surrounding cranium, causing the tissue to fold back on itself to fit a smaller volume. Degree of folding is related to the processing capabilities.  The Cerebrum and its Lobes The cerebrum is made by two hemispheres. It is the major Forebrain structure and most recently expanded feature of the mammalian CNS  Cerebral Circulation The brain is covered by blood vessels. Emerge from the neck and wrap around brainstem , cerebrum, cerebellum to finally penetrate inside the brain to supply inner regions. Brain’s Internal Features Gray and White Matter  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 Cerebral Ventricles The Cerebral Ventricles The Cerebrospinal Fluid (CSF)  The Cerebrospinal Fluid (CSF) The CSF serve the CNS as a: Source of electrolytes Protective/supportive medium Conduit for neuro-active and metabolic products (wastes removal) Secreted by specialized epithelial cells (Ependymal Cells) found mainly on the roofs of the ventricles; tight junctions between cells prevent CSF from spreading to the adjacent tissue. The Cerebral Ventricles Comparative Brain Evolution and Development  Major Divisions of the Vertebrate Brain Area Also Known as Major Structures Forebrain Prosencephalon (“forward-brain) Forebrain Diencephalon ("between-brain") Thalamus, hypothalamus * Forebrain Telencephalon ("end-brain”) Cerebral cortex, hippocampus, basal ganglia Midbrain Mesencephalon ("middle-brain") Tectum, tegmentum, superior colliculus, * inferior colliculus, substantia nigra Hindbrain Rhombencephalon Medulla, pons, cerebellum (literally/"parallelogram-brain") * * Brain Stem The Human Brainstem  The Hindbrain Consists of the: – Medulla – Pons – Cerebellum – Reticular Formation Located at the posterior portion of the brain Hindbrain structures, the midbrain, and other central structures of the brain combine and make up the Brainstem  The Hindbrain – The Medulla The 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 – Pyramidal/Lemniscus Decussations: axons from each half of the brain cross to the opposite side of the spinal cord such that the left hemisphere controls the muscles of the right side of the body and the right hemisphere controls the left side. The Medulla - Decussations Medulla - Cranial Nerves Allow the medulla to control sensations from the head, muscle movements in the head, and many parasympathetic outputs  The Cranial Nerves NumberandName 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 third of the tongue; control of swallowing, salivation, throat movements during speech X. Vagus Sensations from neck and thorax; control of throat, esophagus, and larynx parasympathetic nerves to stomach, intestines, and other organs XI. Accessory Control of neck and shoulder movements XII. Hypoglossal Control of muscles of the tongue Cranial nerves III. IV. and VI are coded in red to highlight their similarity: control of eye movements. Cranial nerves VII, IX, and XII are coded in green to their similarity: taste and control of tongue and throat movements. Cranial nerve VII has other important functions as well. Nerve X (not highlighted) also contributes to throat movements, although it is primarily known for other functions.  The Pons and the Reticular Formation Lies on each side of the medulla (ventral and anterior) The term pons is Latin for ―bridge‖ – In the ventral portion we have pontine nuclei, relay of movement and sensation to the cerebellum – Dorsal there are structure involved in respiration, taste and sleep – Reticular Formation: Midbrain/Medulla area in which nuclei and fiber pathways are mixed, producing a netlike appearance; associated with sleep– wake behavior and behavioral arousal; also called the reticular activating system (RAS)  The Hindbrain – The Cerebellum Structure located in the hindbrain with many deep folds – Helps regulate motor movement, balance, and coordination, fine tuning of movements. – Also important for shifting attention between auditory and visual stimuli – More recent anatomical and functional evidences have shown that it is implicated in language and other cognitive functions The Hindbrain – The Cerebellum  The Midbrain Contains the following structures – Tectum: roof of the midbrain – Superior colliculus and inferior colliculus: processes sensory information – Tegmentum: contains nuclei for cranial nerves and part of the reticular formation – Substantia nigra: gives rise to the dopamine- containing pathway facilitating readiness for movement Sagittal Section Through the Human Brain  Pituitary Gland It lies between the cerebrum and brainstem, involved in homeostatic regulation of body functions The Diencephalon Information Routes from Thalamus to Cerebral Cortex  Thalamus Composes the majority of the diencephalon. Forms most of the walls of the 3rd ventricle. Acts as relay center for all sensory information (except olfactory) to the cerebrum Not passive relay station: acts as a gatekeeper, preventing/enhancing sensory stimuli depending on the behavioral state. The Thalamus is a complex region capable of substantial information processing  Hypothalamus Contains neural centers for hunger, thirst, and body temperature. Contributes to the regulation of sleep, wakefulness, emotions and sexual activity. Stimulates hormonal release from anterior pituitary. Produces ADH and oxytocin. Coordinates sympathetic and parasympathetic reflexes.  Pituitary Gland Posterior pituitary: –Releases ADH and oxytocin. Anterior pituitary: –Regulates secretion of hormones of other endocrine glands.  The Forebrain Largest and most recently evolved region of the mammalian brain 1. Cerebral Cortex: perception, planning, emotions, memory – Allocortex – Neocortex 2. Basal Ganglia: control of voluntary movement and role in cognitive functioning The Cerebral Cortex (3 to 4) Allo vs Neo Cortex The Allocortex (The Limbic System) Consists of a number of other interlinked structures that form a border around the brainstem, generally associated with motivation and emotions. – Hippocampus: memory consolidation – Amygdala: role in fear and anxiety – Cingulate Cortex: emotion formation, memory, learning, linking behavioral outcomes to motivation – Olfactory Bulbs: organs detecting odors and providing input to structures responsible for the perception of smell The Allocortex (The Limbic System)  The Neocortex Less than 5 mm thick (gray matter) Contains 10 billion neurons and billions of synapses. Intricate neural circuitry is responsible for many unique human traits: – Reasoning – Mathematical ability – Language skills – Imagination – Personality traits – Artistic talent – Sensory perception – Motor function Cerebral Cortex  Organization of the Cerebral Cortex Sensory Areas, receive sensory inputs and translate into perception/awareness: – Primary somatic sensory cortex, in the parietal lobe, terminations from skin, musculoskeletal system and viscera; information about touch, pain, temperature, itch, body position. Sensory fibers cross to the opposite side as they ascent in spinal cord or medulla; they pass through the thalamus that relay to the cortex. – Visual, Auditory, Olfactory and Gustatory cortices receive special senses, vision, hearing, olfaction (smell), taste – devoted cortical areas Motor Areas, direct skeletal muscles movement Association Areas, integrate information from sensory and motor areas directing the voluntary behaviors. They create transform sensory stimuli into Perception (awareness), brain’s interpretation of sensory stimuli (interpretation of colors, smells, sounds). Sometimes we perceive what our brain expects to perceive! Organization of the Cerebral Cortex The Homunculus Processing of Sensory Input and motor Output  Associative cortex information flow Sensory information is processed and sent from receptors along parallel pathways through primary sensory cortex and unimodal association cortex to the posterior multimodal association cortex of each hemisphere—the posterior parietal and temporal cortices. The posterior multimodal association cortex is highly connected to the anterior association areas which in turn are responsible for conceptual cognitive functions and planning motor actions. After planning motor actions in the anterior association area, the actual processing of the motor response output is the reverse of processing in the sensory (input) system. The premotor cortex is rostral to the motor cortex  The Forebrain – The Basal Ganglia 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 – Also important for attention, language planning, and other cognitive functions The Basal Ganglia The Basal Ganglia  The Spinal Cord, Part 1 Part of the CNS found within the spinal column – Communicates with the sense organs and muscles, except those of the head – Segmented structure – Entering dorsal roots carry sensory information and exiting ventral roots carry motor information – Cell bodies of the sensory neurons are located in clusters of neurons outside the spinal cord – the dorsal root ganglia – Cell bodies of the motor neurons are inside the spinal cord  The Spinal Cord, Part 2 Consists of two types of matter – Grey 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 Each segment sends sensory information to the brain and receives motor commands A bilateral pair of spinal nerves arise from each segment. The brain and SC are protected by the meninges: Dura Mater, Arachnoid membrane, Pia Mater The Dura is associated with veins, the Arachnoid with CSF, the Pia with arteries.  Anatomy of the Spinal Cord: the Gray Matter Gray Matter: Just before they joining the SC, each spinal nerve split into 2 branches, ROOTS unmyelinated nerve cell bodies, dendrites and axons; a cluster of cell bodies is called nucleus (nuclei, plr). White Matter: mostly myelinated axons, very few cell bodies; bundles of axons connecting different nucli of the brain are known as tracts. Dorsal vs Ventral Horns  The White Matter Dorso-ventral organization of Ascending and Descending tracts. Propriospinal tracts remain within the SC. These tracts are organized into vertical columns. Gray Matter and White Matter  The SC can function as an integrating center: The Spinal Reflex Unconscious responses to a stimulus; only sensory and motor neurons are involved. + + - Knee-Jerk Reflex Involves Spinal Cord, not Brain. The SC can function as a self- contained integrating centre. Spinal interneurons can route information to and from the brain. Spinal reflexes play a critical role in the coordination of body movement. Anatomy of a nerve A Cross-Section Through the Spinal Cord  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 – The parasympathetic nervous system Autonomic pathways consist of two efferent neurons in series Ganglion vs Nucleus (cluster of nerve cell bodies) Divergence: targets 8/9 post ganglionic neurons  Neurotransmitters in the ANS Postganglionic axons of the parasympathetic nervous system mostly release acetylcholine as a neurotransmitter The sympathetic nervous system mostly uses norepinephrine  The Sympathetic Nervous System A network of nerves that prepares the organs for rigorous activity – Increases heart rate, blood pressure, respiration, etc. (―fight or flight‖ response) – Composed of ganglia on the left and right of the spinal cord The Parasympathetic Nervous System Facilitates vegetative and nonemergency responses – Decreases functions increased by the sympathetic nervous system – Composed of long preganglion axons extending from the spinal cord and short postganglionic fibers that attach to the organs themselves – Dominant during our relaxed states Normal activities reflect a balance between the two divisions of the autonomic system Most of the times, autonomic control of the body function ‗seesaws‘ back and forth between the two branches of the autonomic system: they cooperate to finetune various processes. Antagonistic control is a hallmark of the autonomic division Many internal organs are under antagonistic control: one autonomic branch is excitatory, the other is inhibitory. Heart: sympathetic system increases heart rate parasympathetic system decreases it Heart rate can be regulated by altering the proportion of sym or para control Smooth muscles of blood vessels do not have a parasympathetic innervation, they rely only on the tonic control of the sympathetic system.  Autonomic and Enteric Nervous Systems: Visceral Relations ENS: controlling the gut – The ENS is a network of neurons embedded in the lining of the gastrointestinal tract. – It controls bowel motility, secretion, and blood flow to permit fluid and nutrient absorption and to support waste elimination. – The brain and ENS connect extensively through the ANS, especially via the vagus nerve.  Autonomic and Enteric Nervous Systems: Visceral Relations The ENS is formed by a network of neurons embedded in the lining of the gastrointestinal tract. Congregations of neurons form ganglia that send projections to the ANS and CNS, in part through the vagus nerve (cranial nerve 10), to control gut function. © Cengage Learning 2016  Autonomic and Enteric Nervous Systems: Visceral Relations ENS interacts with gut bacteria, known collectively as the microbiome. – About 3.9 × 1013 microbiota populate the adult gut, outnumbering the host cells by a factor of 1.3. – Microbiota influence nutrient absorption and are a source of neurochemicals that regulate an array of physiological and psychological processes. This relationship has inspired the development of a class of compounds known as psychobiotics, live microorganisms used to treat behavioral disorders. – Thus, microbiota can influence both the CNS and ENS, leading to changes in behavior. THANK YOU!  3.3 Research Methods The main categories of research methods to study the brain include those that attempt to: – Examine the effects of brain damage – Examine the effects of stimulating a brain area – Record brain activity during behavior – Correlate brain anatomy with behavior  Effects of Brain Damage Brain damage can produce an inability to recognize faces, an inability to perceive motion, changes in emotional responses, and many more effects – Ablation: removal of a brain area – Lesion: damage to a brain area, often done for research – Stereotaxic instrument: used to damage structures in the interior of the brain A Stereotaxic Instrument Electrophysiology  Transcranial Magnetic Stimulation Application of an intense magnetic field to a portion of the scalp to temporarily deactivate neurons below the magnet – Allows researchers to study behavior with a brain area active, then inactive, then active again Apparatus for Magnetic Stimulation of a Human Brain  Effects of Brain Stimulation Stimulation of a brain area should increase behavior Optogenetics: a technique that allows researchers to turn on activity in targeted neurons by a device that shines a laser within the brain – Electrodes can probe the brain of a person undergoing brain surgery – A limitation is that complex behaviors depend on temporal pattern of activity in many areas  Optogenetics https://youtu.be/Nb07TLkJ3Ww https://youtu.be/ChogEq7fBgE  Recording Brain Activity – EEG Electroencephalograph (EEG): records electrical activity produced by various brain regions – Can produce evoked potentials that self- reports sometimes do not reveal Electroencephalography Recording Brain Activity – MEG and PET Magnetoencephalograph (MEG): similar to EEG but measures faint magnetic fields generated by brain activity instead Positron-emission tomography (PET): records emission of radioactivity from injected radioactive chemicals to produce a high-resolution image A Result of Magnetoencephalography A PET Scanner  Recording Brain Activity – fMRI Functional magnetic resonance imaging (fMRI): modified version of an MRI that uses oxygen consumption in the brain to provide a moving and detailed picture – Safer and less expensive than PET – Comparison tasks are used to compare the brain pictures while person is engaged in different activities and recordings can allow researchers to predict the behavior An fMRI Scan of a Human Brain Subtraction for a Brain Scan Procedure Correlating Brain Anatomy with Behavior – Phrenology The process of relating skull anatomy to behavior – One of the first ways used to study the brain – Yielded few, if any, accurate results A Phrenologist‘s Map of the Brain Affective Faculties Propensities ? Desire to live Allmentlveness 1 Destructiveness 2 Amativeness 3 Philoprogenitfr/eness 4 Adhesiveness 5 Inhabitiveness 6 Combativeness 7 Secretiveness 8 Acquisitiveness 9 Constructiveness Affective Faculties Sentiments 10 Cautiousness 11 Approbatlveness 12 Self-esteem 13 Benevolence 14 Reverence 15 Firmness 16 Conscientiousness 17 Hope 18 Marvelousness 19 Ideality 20 Mirthfulness 21 Imitation Intellectual Faculties Perceptive 22 Individuality 23 Configuration 24 Size " 25 Weight and resistance 26 Coloring 27 Locality 28 Order 29 Calculation 30 Eventuality 31 Time 32 Tune 33 Language Intellectual Faculties Reflective 34 Comparison 35 Causality Correlating Brain Anatomy with Behavior – Modern Methods Identify peculiar behaviors and look for abnormal brain structures or function – These abnormal brain structures can be identified using: Computerized axial tomography (CAT scan) Magnetic resonance imaging (MRI) Correlating Brain Anatomy with Behavior – CAT and MRI Computerized axial tomography (CAT scan): inject dye into the blood and a pass x-rays through the head – Rotate scanner slowly until a measurement has been taken at each angle and a computer constructs the image – Used to identify tumors and abnormalities Magnetic resonance imaging (MRI): apply a powerful magnetic field to image the brain CT Scanner A View of a Living Brain Generated by Magnetic Resonance Imaging  Methods of Studying Brain-Behavior Relationships Examine Effects of Brain Damage Study victims of stroke, etc. Used with humans; each person has different damage Lesion Controlled damage in laboratory animals Ablation Removal of a brain area Gene knockout Affects wherever that gene is active (eg., a receptor) Transcranial magnetic stimulation Intense application temporarily inactivates a brain area Examine Effects of Stimulating a Brain Area Stimulating electrodes Invasive; used with laboratory animals, seldom with humans Transcranial magnetic stimulation Brief, mild application activates underlying brain area Record Brain Activity during Behavior Record from electrodes in brain Invasive; used with laboratory animals, seldom humans Electroencephalograph (EEG) Records from scalp; measures changes by milliseconds, but with low resolution of location of the signal Evoked potentials Similar to EEG but in response to stimuli Magnetoencephalograph (MEG) Similar to EEG but measures magnetic fields Positron emission tomography (PET) Measures changes over both time and location but requires exposing brain to radiation Functional magnetic resonance Measures changes over about 1 second, identifies location within 1 to 2 mm, no use of radiation imaging (fMRI) Correlate Brain Anatomy with Behavior Computerized axial tomography (CAT) Maps brain areas, but requires exposure to X-rays Magnetic resonance imaging (MRI) Maps brain areas in detail, using magnetic fields  Brain Size and Intelligence Research has not supported that a larger brain is correlated with higher intelligence Brain-to-body ratio research has some limited validity Moderate correlation exists between IQ and brain size (.3) Amount of grey and white matter may also play a role IQ is correlated with amount of grey matter Relationship of Brain Mass to Body Mass Across Species Cortical Areas Whose Size Correlated with IQ  Brain Size and Intelligence – Gender Comparisons Men have larger brains than women but equal IQs – Various differences in specific brain structures exist between men and women, but the number of neurons are about the same for both – Explanations in differences in cognitive abilities can perhaps be better explained by interest than abilities (i.e., more male chess masters because more boys play chess)  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 Views of the Brain  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, drinking, sexual activity, anxiety, and aggression The Limbic System  The Forebrain – Subcortical Regions Structures underneath the cortex – 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 The thalamus and the hypothalamus together form the ―diencephalon‖ Information Routes from Thalamus to Cerebral Cortex The Forebrain – The Pituitary Gland and Basal Ganglia 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 – Also important for attention, language planning, and other cognitive functions The Basal Ganglia  The Forebrain – The Basal Forebrain Composed of several structures that lie on the ventral surface of the forebrain Contains the nucleus basalis – Receives input from the hypothalamus and basal ganglia – Sends axons that release acetylcholine to the cerebral cortex – Important in arousal, wakefulness, and attention Basal Forebrain  The Forebrain – The Hippocampus A large structure located between the thalamus and cerebral cortex – Toward the posterior portion of the forebrain – Critical for storing certain types of memory, particularly new events The Forebrain – The Hippocampus  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 The Cerebral Ventricles The Cerebral Ventricles  3.2 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 Volumes of the Cortex and the Rest of the Brain Relative Sizes of Five Brain Components in Insectivores and Primates  Organization of 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 Six Laminae of the Human Cerebral Cortex Columns in the Cerebral Cortex The Four Lobes of the Cerebral Cortex Occipital lobe Parietal lobe Temporal lobe Frontal lobe Areas of the Human Cerebral Cortex  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 – Damage can result in cortical blindness  The Parietal Lobe, Part 1 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 Approximate Representation of Sensory and Motor Information in the Cortex  The Parietal Lobe, Part 2 Essential for spatial information as well as numerical information – Example: using one‘s fingers to count represents an overlap of spatial and numerical tasks  The Temporal Lobe Located on the lateral portion of each hemisphere near the temples – Target for auditory information and essential for processing spoken language Also responsible for complex aspects of vision, including movement and some emotional and motivational behaviors – Klüver-Bucy syndrome associated with temporal lobe damage  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) 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  Prefrontal Lobotomy Surgical disconnection of the prefrontal cortex from the rest of the brain – In the 1940s and 50s, 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 Results of a Prefrontal Lobotomy Before/After Prefrontal Lobotomy  How Do the Parts Work Together? 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  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? An Illusion to Demonstrate Binding Reticular Formation and the Raphé System Reticular Formation Serotonin nuclei: Ascending and descending components: Mood, sleep, memory, cognition Promote arousal – Controls motor areas of the SC  Dopamine Modulatory activity of the reticular formation are often involved in Motivation and in regulating behaviors that responds to primary needs: Hunger, Thirst, Sleep. Modulatory systems are responsible for: Focus senses to stimuli that are relevant to these needs Reinforcement of behaviors through rewarding Dopamine mediate rewarding outcomes It acts as a learning signal: pavlonian principles Dopamine Dopamine and reward