OTH 509: basal ganglia 2023 with verified questions and answers

the basal ganglia is an ________ system. Extra-Pyramidal Motor system what does it mean to be an Extra-Pyramidal motor system? - has no direct descending input to the LMN (but connects and talks to everything that goes to the LMN) - communicates and uses all of the descending pathways - comprised of the cerebellum and basal ganglia what is the basal ganglia and what does it do? - a group of functionally related nuclei of grey matter buried deep in the cerebral cortex - motor, cognitive, and emotional functions what is the nucleus accumbens? most anterior part of the caudate and lentiform - remember AA (anterior - accumbens) the lentiform nucleus is made up of the... putamen and globus pallidus the caudate and lentiform together is called the... corpus striatum what two structures is the substantia nigra made up of? - pars compacta - pars reticulata the caudate and putamen together is called the... neostriatum the globes pallidus is also called the... paleostriatum what is the basal ganglias relationship to the internal capsule? - connections that loop and transverse the internal capsule - therefore, these fibers are sometimes damaged in lesions in the capsular region what area of the basal ganglia is specialized to receive input? - neostriatum - nucleus accumbens where does the neostriatum and nucleus accumbens receive info from? - cortex through corticostriate fibers - the thalamus through centromedian-thalamostriate fibers - substantia nigra through nigrostriatal fibers what are the output areas of the basal ganglia? - globus pallidus internal - sunstantia nigra - subthalamus what is special about the output fibers of the substantia nigra? - the neurons leaving the substantia nigra contain dopamine - the loss of these dopaminergic fibers causes Parkinson's disease what are the two internal circuits of the basal ganglia? - substantia nigra (pars compacta) to the striatum (caudate) and back - sub thalamic input to the globus pallidus and back what is the one exception to the caudate only receiving input? - cuadates receives input in every circumstance except for one - in the internal circuit the caudates receives input from the substantia nigra, but also sends info back what is the one exception to the subthalamus only sending information? - the subthalamus sends info in every circumstance except for one - in the internal circuit, the subthalamus sends info to the globus pallidus, but the globus pallidus sends info back that the subthalamus receives since the basal ganglia has no direct descending input to the LMN, how does it influence the motor program? - by sending info back to the cortex with its analysis of the situation and telling it what to do where does information from the basal ganglia have to stop before getting to the cortex? - stops at the ventral anterior and ventral lateral nuclei of the thalamus explain the direct circuit of the basal ganglia: - Excitatory Input to Caudate/Putamen from Cortex - Inhibitory Input sent to Globus Pallidus (Internal Part) - Globus Pallidus outflow to Thalamus is normally inhibitory, but now it is disinhibited or facilitated - VA/VL are driven to Facilitation - Cortex is Facilitated explain the indirect circuit of the basal ganglia: - Excitatory Input to Caudate/Putamen from Cortex - Inhibitory Input sent to Globus Pallidus—External Part - Globus Pallidus External usually inhibits subthalamus, so dis-inhibition occurs - Subthalamus Facilitates Globus Pallidus-Internal Part which is Inhibitory - Globus Pallidus Internal sends inhibitory input to thalamus - VA/VL are less active and Cortex is Inhibited explain the complex loop circuit of the basal ganglia and what it does: - Pre-frontal Cortex---Caudate----SN/GP------VA thalamus----Pre-frontal Cortex - Associated with Movement Initiation/Converting Ideas to Actions/Socially Appropriate Behavior explain the motor loop circuit of the basal ganglia and what it does: - Motor Areas of Cx (M1, PFC, SMC)-----Putamen----SN/GP-----VL thalamus---Motor Cortex - Associated with Scaling of Movement; Movement Preparation explain the limbic loop circuit of the basal ganglia and what it does: - Cingulate Cortex----ventral striatum/NA----SN/GP-----Cingulate Cortex - Associated with motivated behavior functions of normal motor control of the basal ganglia include: - Postural sets - Dampens undesirable movements - Scales movement in amplitude and force - Significance of environmental cues common signs and symptoms of Parkinson's disease: - A resting tremor/Pill Rolling - Micrographia - Festinating Gait Flexed Postural Set Difficulty Initiating Movement Disorder of Movement Scale (Movements are Small) Cogwheel Rigidity what is Festinating Gait? - small rapid steps resulting from a forward-tilted head and trunk posture - no clear weight shift, crouch low to the ground, don't want to pick up feet, start and stop doesn't work what is Cogwheel Rigidity? Type of rigidity in which the increased tone is released by degrees during passive range of motion so it feels like small, regular jerks Basal Ganglia Dysfunction is associated with Bradykinesia, what is that? slow movement Basal Ganglia Dysfunction is associated with Akinesia, what is that? difficulty starting movement Basal Ganglia Dysfunction is associated with chorea, what is that? proximal movement that looks like twitching Basal Ganglia Dysfunction is associated with athetosis, what is that? distal and worm like movement, often associated with hyperextension of the joints Basal Ganglia Dysfunction is associated with tremors, what is that? oscillatory movement around a joint Basal Ganglia Dysfunction is associated with Ballimus, what is that? "flinging", stroke that affects the subthalmic nucleus, completely aware Basal Ganglia Dysfunction is associated with Dystonias, what is that? intense contractions that build slowly and persist or decay slowly, uncomfortable