Chapter 7 Part 2
Chapter 7 Part 2 35184
Popular in Intro to Physiological Psych
Popular in Psychology (PSYC)
This 5 page Class Notes was uploaded by Alex Buckley on Sunday October 9, 2016. The Class Notes belongs to 35184 at Santa Barbara City College taught by Dr. Bursten in Fall 2016. Since its upload, it has received 3 views. For similar materials see Intro to Physiological Psych in Psychology (PSYC) at Santa Barbara City College.
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Date Created: 10/09/16
Connections from the Brain to the Spinal Cord - Messages from the brain must reach the medulla and spinal cord to control muscles - Corticospinal tracts are paths from the cerebral cortex to the spinal cord - Two such tracts: o Lateral (to the side) corticospinal tract o Medial (to the middle) corticospinal tract Lateral Corticospinal Tract - Fine, controlled movements - A set of axons from the primary motor cortex, surrounding areas, and red nucleus to the spinal cord o Controls movement in peripheral areas (hands and feet) o Red nucleus: a midbrain area with output mainly to the arm muscles - Axons extend from one side of the brain to the opposite side of the spinal cord, and control opposite side of the body Medial Corticospinal Tract - General, gross movements - A set of axons from many parts of the cortex o Reticular formation, midbrain tectum, and vestibular (balance control) nucleus - Vestibular nucleus is a brain area that receives information from the vestibular system Axons and the Spinal Cord - Axons go to both sides of the spinal cord o Allows control of muscles of the neck, shoulders and trunk o Enables movements such as walking, turning, bending, standing up, and sitting down Cerebellum - Coordination of movement - Learned motor habits o E.g. brushing your teeth, swinging a bat, playing a piano o Once learned, it is coded in the cerebellum and can be preformed without thinking - Cerebellar damage or alcohol intoxication many lead to deficits in rapid ballistic movements o Ballistic movement: only one trajectory o Guided movement: modified by peripheral movement, cognitive desires/thoughts - Purkinje cells are the most numerous and are more metabolically active than other cells o This makes the cerebellum more sensitive to stress than other areas o Short and long term physical stress, e.g. from boxing or football cause cerebellar ataxia, the “punch drunk” or “drunken sailors gait” - Linked to habit formation, timing, certain aspects of attention, and other psychological functions as well as motor functions - Receives input from the spinal cord, from each of the five senses via cranial nerve nuclei, and from the cerebellar cortex - Action potentials of parallel fibers (axons parallel to one another) excite one Purkinje cell (very flat cells in sequential planes) after another - Purkinje cells inhibit cells in the interior nuclei of the cerebellum and the vestibular nuclei in the brain stem Basal Ganglia - A group of subcortical structures in the forebrain o Caudate nucleus May be involved in OCD Involved in mediation of “pleasurable” effects of high sugar/fat foods o Putamen—may be involved in motor synchronization to the auditory stimuli—e.g. dancing - Brake hypothesis o Principal neurotransmitters are ACh (Acetylcholine), GABA (GammaAmino Butyric acid) and dopamine o Overall effect on thalamus is inhibitory o To sit still, you must “put on the breaks” on all movements except those reflexes that maintain an upright posture o To move, you must apply a break to some postural reflexes and release the brain on voluntary movement o So basal ganglia select movement by ceasing inhibition o Small disturbances can throw the whole system out of whack, often in unpredictable ways. Deficits tend to fall into one of two categories Presence of extraneous unwanted movements (Tourette’s) An absence or difficulty with intended movements (reaching for water bottle and missing it)