Cortical and subcortical structures Flashcards
What does the PNS consist of?
Somatic Nervous system
*
Sensory information from skin, joints, muscles, etc. to and from the CNS;
*
Sends motor stimuli from CNS to muscles (voluntary movement);
Autonomic Nervous System (ANS)
*
Regulates involuntary movement;
*
Controls bodily functions e.g. blood pressure, berating, etc.
*
It is subdivided into sympathetic and parasympathetic nervous system
What is gastrulation?
invagination (the action or process of being turned inside out or folded back on itself to form a cavity or pouch) of embryo cells in early phases to define the midline of vertebrae embryos. Invaginations starts at around day 18 and by day 20 neural plate starts forming.
Day 22 – neural tube is formed; mesoderm becomes thicker; may develop into axial musculature and skeleton
Day 24 – neural tube becomes rudimentary spinal cord; neural crest becomes a rudimentary sensory and autonomic ganglia (PNS); anterior neural fold expand to form the brain hemispheres.
What does the hindbrain consist of?
- Medulla – breathing and circadian rhythms;
- Pons – links with the cerebellum;
- Cerebellum – coordinates movements;
What does the midbrain consist of?
- Crus cerebri;
- Tactum (colliculi);
- Tegmentum (red nuclei and substantia nigra);
- Cerebral aqueduct;
What does the forebrain consist of?
telenchephalon and diencephalon
What are the parts of the telencephalon?
- Neocortex
- Basal ganglia
- Limbic system
- Olfactory bulb
What are the parts of the diencephalon?
- Thalamus
* Hypothalamus
Gross structure of the neocortex
- 6 layers – numbered I to VI, starting from the surface; size and density of cells’ bodies varies across layers;
- Pyramidal cells – large, multipolar – large dendrites and long axons, projection neurons;
- Stellate – star shaped – smaller soma, shorter axon, local information processing;
- Efferent cells – send to others; afferent- receives info;
- Thickness of each layer varies across different cortical areas, according to the local function; sensory areas – thick layer IV; motor area – thick layer V
What are cytoarchitectonics?
variation of thickness and cell composition of each of the six layers – basis of the Broadmann map – 52 Broadmann areas (BA);
What are associative fibers?
- connect areas within the same hemisphere
- Arcute fasciculus;
- Uncinated fasciculus;
- Superior and inferior longitudinal fasciculi;
- Cinguale fasciculi;
- Superior and inferior occipital frontal fasciculus;
What are fibers of projections?
send (efferent) receive (afferent) information between the cortex and other structures of the brain ( mainly the thalamus through internal capsula);
What are the structures of the basal ganglia?
* Globus pallidus- lenticular nucleus ----à * Putamen * Caudate Nucleus -à Striatum ------------à Corpus Striatum * Subthalamic nucleus * Substantia nigra
What is the role of the basal ganglia
Complex function – involvement in movement and motor control; DO NOT INITUATE movements, involved in a loop of modulation that is constantly active e.g. gross postural adjustment and monitoring the force to be applied to a task;
Receives direct input from cortical areas and the limbic system, however, THEY DO NOT PROJECT DIRECTLY TO THE CORTEX, but travel through the thalamus
What are the main neurotransmitters of the basal ganglia
GABA; Dopamine and Glutamate
Describe the basal ganglia malfunction in Parkinson’s disease
Parkinsons’ disease – malfunction in BG, causes tremor, bradykinesia, muscle rigidity, motor coordination –> Reduction of dopamine is mainly due to the death of dopaminergic neurons in the substantia nigra; -> lack of input through the nigrostriatal path to putamen -> internal pallidus more activated -> thalamus more hinibeted ->less activation towards the cortex -> less movement;
