NSCI 110 1st Edition Lecture 30 Outline of Last Lecture I The spinothalamic tract consists of lateral and dorsal pathways II Pain is an unpleasant sensory and physical experience a Responses to pain may be initial or later b There are many classifications of pain depending on certain psychological and physiological factors III Nociceptors detect damage or potential damage a Responsive to mechanical chemical or thermal stimuli IV Perceiving pain occurs in the frontal lobe Outline of Current Lecture I Pathways from the lateral spinathalamic tract extend to a Reticular formation and periaqueductal gray b Tectum c Amygdala d Hypothalamus II Visceral pain has the following characteristics a Wide variance of sensitivity b Weak pain and injury relationship c Is diffuse poorly localized d Exhibit exaggerated autonomic responses III The hypothalamus performs acute and chronic stress responses a Controls many preganglionic spinal cord neurons IV The Gate Theory of Pain claims that different sensory pathways compete for arousal and perception in response to a stimuli a Certain methods reduce our perception of pain by inhibiting nociceptive receptor pathways V Stimulation of the periaqueductal gray matter reduces perception of pain VI The vestibular system is responsible for orienting movements and controlling balance a Semicircular canals and otolith organs work together to help us perceive our body s position in space i Utricle and saccule VII The secondary somatosensory cortex receives input from the primary somatosensory cortex a Gives rise to dorsal and ventral streams in nearby cortical regions VIII Aggression has a neural basis in the periaqueductal gray and hypothalamus a There are numerous subcategories of aggressive behaviors Current Lecture These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Pathways from the anterolateral system lateral ST tract have extensive connections o Reticular formation and periaqueductal gray arousal o Tectum orienting responses o Amygdala emotional responses o Hypothalamus hormonal and cardiovascular responses Unique features of visceral pain internal organs o Wide variance of sensitivity Liver has low sensitivity to pain Urethra has high sensitivity o Pain and injury relationship is weak GI tract burning is not perceived but twisting is excruciating The heart is extremely sensitive to decreased blood flow o Is diffuse poorly localized Referred to the periphery o Exaggerated autonomic reactions such as increased sweating paleness blood pressure changes heart rate Hypothalamus role in autonomic control o Drives preganglionic cells activity o Acute stress response Hypothalamus sympathetic innervation of adrenal medulla epinephrine release occurs between post ganglionic cell and target cells o Chronic stress response Hypothalamus anterior pituitary gland adrenal cortex cortisol o Hypothalamus controls thousands of preganglionic cells in the spinal cord Gate Theory of Pain states that activities in different sensory pathways compete for arousal and perception o Competition between dorsal ST tract and lateral ST tract o Haptic proprioceptive stimulation can reduce pain perception by activating inhibitory interneurons that reduce nociception o Acupuncture and massage therapy can reduce our perception of pain Periaqueductal gray matter o When stimulated can decrease our perception of pain o Can activate brainstem pathways that project to the dorsal spinal cord to inhibit lateral ST tract neurons o Some neurons project to the hypothalamus autonomic regulation and amygdala regulating emotion The vestibular system and balance o Each ear s vestibular organ consists of three semicircular canals and otolith organs utricle and saccule o Vestibular organ functions include Body position in relation to gravity Changes in direction and speed o Any head motion causes the movement of endolymph fluid in semicircular canals This pushes the cilia of hair cells in the cochlea causing them to bend Cilia bending causes hair cell receptor potentials and action potentials in the neurons of the vestibular nerve Depolarization move to right and hyperpolarization move to left o The utricle and saccule also contain hair cells embedded within a gelatinous substance that contains otoconia made of otoliths calcium carbonate crystals Movement causes a shift of the gelatinous substance and the cilia bend generating action potentials in vestibular nerve axons o Somatosensory cortex receives sensory input Secondary cortex receives input from primary somatosensory cortex Refines the construction of perceptions and projects to the frontal cortex Primary cortex is organized into four separate homunculi This cortex confirms that movements have occurred Damage does not disrupt movement plans but disrupts how movements are performed their execution may be fragmented Apraxia is the inability to complete a plan of action accurately This cortex is a node for the dorsal and ventral streams and signals widely to the motor cortex Dorsal how stream o Works without conscious awareness o Vision for action o Visual and somatosensory info integrated for appropriate movement o Shapes and directs hand while grasping Ventral what stream AGGRESSION Neural basis o Stimulation of the periaqueductal gray in the midbrain and the hypothalamus change aggressive responses o Temporal lobe tumor induced assault without provocation Aggression is behavior that causes harm damage or destruction o How to categorize It is often expressed as a mix of types Affective associated with fear threat reaction defensive Predatory proactive premeditated aggression o Affective aggression in cats hissing ears flat body low higher blood pressure and heartrate piloerection paw striking Stimulation of medial hypothalamus or dorsolateral PAG Cerebral cortex not essential o Predatory aggression in cats highly directed to prey item stalking aiming to bite back of neck of prey Stimulation of lateral hypothalamus or ventral PAG Cerebral cortex necessary