Chapter 4 Anatomy of the Nervous System

chapter 4 Frontal lobe damage Phineas Gage, 1848

chapter 4 Frontal lobe damage Travis Bogumill, 1998 Jarod Behee, 2007

Wilder Penfield: Mapping the Cortex, 1947

Modern techniques for studying the brain Lesion damage to a brain area (electrical or chemical) Ablation removal of brain area Stereotaxic instrument a device that allows for precise neurosurgical procedures Sham lesion performing identical procedures except for damaging the brain produced by an experimenter in a control subject

Modern techniques for studying the brain Positron-emission tomography (PET Scan) records emission of radioactivity from injected radioactive chemicals to produce a high- resolution image shows where activity occurs in the brain

Modern techniques for studying the brain Recording brain activity involves using a variety of noninvasive methods including: Magnetic Resonance Imaging (MRI) involves the application of a powerful magnetic field to image the brain good for viewing soft tissue

Modern techniques for studying the brain Electroencephalography (EEG) Records electrical activity produced by cortical regions of the brain Produces a record of brainwaves. Widely used for sleep research

Structure of the Vertebrate Nervous System Neuroanatomy is the anatomy of the nervous system. Refers to the study of the various parts of the nervous system and their respective function(s). The nervous system consists of many substructures, each comprised of many neurons.

Structure of the Vertebrate Nervous System The Nervous System is comprised of two major subsystems: The Central Nervous System (CNS)—brain and spinal cord The Peripheral Nervous System (PNS)

Central Nervous System Brain Comprised of 100 billion neurons “Command Central” of the nervous system Spinal cord the part of the CNS found within the spinal column communicates with the sense organs and muscles below the level of the head Functions according to the Bell-Magendie law

Central Nervous System The Bell-Magendie law states the entering dorsal roots carry sensory information and the exiting ventral roots carry motor information. Figure 4.3: Diagram of a cross-section through the spinal cord. The dorsal root on each side conveys sensory information to the spinal cord; the ventral root conveys motor commands to the muscles. Fig. 4-3, p. 84

Peripheral Nervous System The Peripheral Nervous System (PNS) sends information to the CNS and is comprised of the: Somatic Nervous System Autonomic Nervous System

Peripheral Nervous System The Somatic Nervous System consists of nerves that: Convey sensory information to the CNS. Transmit messages for motor movement from the CNS to the body. Control skeletal muscles

Peripheral Nervous System The autonomic nervous system regulates the automatic behaviors of the body (heart rate, blood pressure, respiration, digestion etc). Divides into 2 subsystems: The Sympathetic Nervous System The Parasympathetic Nervous System

Peripheral Nervous System Sympathetic nervous system: a network of nerves that prepares the organs for rigorous activity by increasing: heart rate blood pressure respiration etc. Responsible for “fight or flight” response

Peripheral Nervous System The parasympathetic nervous system facilitates vegetative, nonemergency responses by the organs. decreases functions increased by the sympathetic nervous system. dominant during our relaxed states.

Anatomical Terms: Views Terms used to describe views when referring to the nervous system include: Ventral: toward the stomach Dorsal: toward the back Ventral Dorsal

Anatomical Terms: Views Terms used to describe views when referring to the nervous system include: Anterior: toward the front end Posterior: toward the back end Lateral: toward the side anterior posterior lateral

Anatomical Terms: Location/direction Terms used to describe location/direction in the nervous system include: Superior: above another part Inferior: below another part

Anatomical Terms: Location/Direction Terms used to describe location/direction in the nervous system include: Lateral: toward the side Medial: toward the midline

Anatomical Terms: Location/Direction Terms used to describe location/direction in the nervous system include: Ipsilateral: on same side Contralateral: on opposite side

Anatomical Terms: Planes/Sections/Cuts Terms referring to planes/sections/cuts: Horizontal: shows brain structures as seen from the top Sagittal: shows brain structures as seen from the side Coronal: shows brain structures as seen from the front Table 4-1, p. 83

Anatomical Terms: Specialized Parts Terms referring to specialized parts of the nervous system: Gray matter: cell bodies and dendrites White matter: axons, mostly myelinated Table 4-1, p. 83

Anatomical Terms: Specialized Parts Terms referring to specialized parts of the nervous system: Tract/projection: set of axons in the CNS Nerve: set of axons in the PNS Nucleus: cluster of neuron cell bodies within CNS Ganglion: cluster of neuron cell bodies in the PNS Table 4-1, p. 83

Anatomical Terms: Specialized Parts Terms referring to specialized parts of the nervous system: Gyrus (pl: gyri): mound on surface of brain Sulcus (pl: sulci): fold/groove separating one gyrus from another Fissure: long, deep sulcus Table 4-1, p. 83

Neuroanatomy Handout #3: Brain Structures The brain can be divided into three major divisions: Hindbrain. Midbrain. Forebrain.

Neuroanatomy Handout #3: Brain Structures The Hindbrain consists of the: Medulla Pons Cerebellum Located at the posterior portion of the brain

Neuroanatomy Handout #3: Brain Structures The medulla (A): Located just above the spinal cord Responsible for vital reflexes such as breathing, heart rate, vomiting, salivation, coughing and sneezing. Cranial nerves allow the medulla to control sensations from the head, muscle movements in the head, and many parasympathetic outputs to the organs.

Table 4-4, p. 88

Neuroanatomy Handout #3: Brain Structures Pons (B) lies on each side of the medulla (ventral and anterior). along with the medulla, contains the reticular formation and raphe system, which work together to increase arousal and readiness of other parts of the brain

Neuroanatomy Handout #3: Brain Structures Cerebellum (C): located posterior to the brainstem with many deep folds helps regulate motor movement, balance and coordination also important for shifting attention between auditory and visual stimuli

Neuroanatomy Handout #3: Brain Structures The midbrain (D) is comprised of the following structures: Superior colliculus: helps process visual info Inferior colliculus: helps process auditory information Substantia nigra – involved in movement

Neuroanatomy Handout #3: Brain Structures Brain stem consists of the: Medulla Pons Midbrain Some forebrain structures

Neuroanatomy Handout #3: Brain Structures Forebrain: most prominent part of the mammalian brain, consisting of: the outer cortex (“cerebral cortex”) subcortical regions

Neuroanatomy Handout #3: Brain Structures The limbic system is associated with motivation, emotion, drives and aggression, and includes: Olfactory bulb Hypothalamus Hippocampus Amygdala Olfactory bulbs send info about smell to cortex

Neuroanatomy Handout #3: Brain Structures Hypothalamus (F) Conveys messages to the pituitary gland to trigger the release of hormones Regulates autonomic nervous system Involved in emotions and drives vital to survival: Eating Drinking Sexual behavior Fear Feeling rewarded

Neuroanatomy Handout #3: Brain Structures Pituitary gland (G)- hormone producing gland found at the base of the hypothalamus. AKA: “Master Gland”

Neuroanatomy Handout #3: Brain Structures Hippocampus is a large structure of the limbic system critical for storing certain types of memory. H.M., 1953

Neuroanatomy Handout #3: Brain Structures Amygdala: almond-shaped structure important for: initial emotional response to stimuli directing motivated behavior at an appropriate target

Neuroanatomy Handout #3: Brain Structures Forebrain structures include: Thalamus (E) - relay station for the sense organs and main source of input to the cortex.

Neuroanatomy Handout #3: Brain Structures Basal Ganglia - comprised of the caudate nucleus, the putamen and the globus pallidus. Associated with planning of motor movement, and aspects of memory and emotional expression .

Neuroanatomy Handout #3: Brain Structures Nucleus basalis: receives input from the hypothalamus and basal ganglia key part of the brain’s system for arousal, wakefulness, and attention

Neuroanatomy Handout #3: Brain Structures The ventricles are four fluid-filled cavities within the brain containing cerebrospinal fluid. The central canal is a fluid-filled channel in the center of the spinal cord.

Neuroanatomy Handout #3: Brain Structures Cerebrospinal fluid (CSF) is a clear fluid similar to blood plasma found in the brain and spinal cord: Provides “cushioning” for the brain Reservoir of hormones and nutrition for the brain and spinal cord Choroid plexus: groups of cells in the 4 ventricles that continually manufacture CSF

Neuroanatomy Handout #3: Brain Structures Meninges: thin membranes surrounding brain and spinal cord

Neuroanatomy Handout #3: Brain Structures The Cerebral Cortex The cerebral cortex is the most prominent part of the mammalian brain and consists of the cellular layers on the outer surface of the brain.

Neuroanatomy Handout #3: Brain Structures The Cerebral Cortex The four lobes of the cerebral cortex: Occipital lobe Parietal lobe Temporal lobe Frontal lobe 2 hemispheres

Neuroanatomy Handout #3: Brain Structures The Cerebral Cortex The Frontal lobe (H): involved in attention, planning, decision-making, etc. contains Broca’s area (principal speech area) (H1) contains Precentral gyrus (primary motor cortex) (H2), responsible for control of fine motor movement

Neuroanatomy Handout #3: Brain Structures The Cerebral Cortex Parietal lobe (I) : involved in body sensations contains postcentral gyrus (I1) (primary sensory area), a main target for touch sensations

Neuroanatomy Handout #3: Brain Structures The Cerebral Cortex Temporal Lobe (J): involved in hearing also responsible for some emotional and motivational behaviors contains primary auditory cortex (J1): Target for auditory information and essential for processing spoken language

Neuroanatomy Handout #3: Brain Structures The Cerebral Cortex Occipital lobe (K): Highly responsible for visual processing contains striate cortex or primary visual area (K1) damage can result in cortical blindness

Neuroanatomy Handout #3: Brain Structures Central sulcus (L) Longitudinal fissure (M) Lateral fissure (N)

Neuroanatomy Handout #3: Brain Structures Corpus callosum (O): large bundle of axons joining the 2 hemispheres Anterior commissure (P): small bundle of axons joining the 2 hemispheres

The Cerebral Cortex The binding problem refers to the question of how the visual, auditory, and other areas of the brain produce a perception of a single object. All areas of the brain communicate with each other