The Hemispheres of the Brain
The medial longitudinal fissure incompletely divides the cerebrum into hemispheres.
The right hemisphere has a special role in maintaining attention, processing visuospatial information and expressing and interpreting emotional information. Lesions of the right hemisphere may result in severe inattention(30).
The left hemisphere assumes the leading role in language in essentially all right handed individuals and 50% of left handed individuals.
The Lobes of the Brain
The frontal lobes are the portions of the cerebrum anterior to the central sulcus and above the lateral fissure. The neurons of the prefrontal cortex respond to sensory stimuli and are thought to integrate motivational events with complex sensory stimuli. They are also involved in inhibiting or delaying motor response to stimuli. The right frontal lobe has been implicated as one potential site of pathologic neurotransmission in AD/HD.
The Basal Ganglia and Thalamus
 
The basal ganglia includes the caudate nucleus, putamen, and globus pallidus. The caudate nucleus sits on the floor of the lateral ventricle, dorsolateral to the thalamus. The cephalic bulge of the caudate nucleus is know as the head. The body passes along the side of the thalamus and tapers to form a tail. The putamen and globus pallidus are known jointly as the lentiform nucleus.
The basal ganglia participates in movements at a high level. Lesions of the basal ganglia can result in difficulty initiating (akinesis), continuing or stopping movements, abnormalities of muscle tone (rigidity) and the development of involuntary movements (tremor or chorea).
Circuits connecting the basal ganglia with the prefrontal cortex may also be important in cognition. Abnormalities of blood flow to these regions are noted in patients with AD/HD.
The thalamus comprises the dorsal portion of the deep gray matter in the rostral midbrain (diencephalon). It serves as the station from which neuronal activity from peripheral sensory receptors, the basal ganglia and the cerebellum is related to the cerebral cortex.
The Hippocampus
The hippocampal formation consists of a large gray matter area that is folded into the most medial edge of the cortex deep to the parahippocampal gyrus. The hippocampus receives highly processed sensory information from the cerebral cortex. Experimental and clinical observations indicate that it plays and important role in learning and memory.
Locus Ceruleus
T he locus ceruleus is the norepinephrine containing nucleus located in the brain stem near the nucleus of CN5 above the fourth ventricle. This nucleus is small but sends axons to all parts of the CNS. Norepinephrine has been found to have inhibitory influences on postsynaptic neurons. In some locations, its primary action is to inhibit spontaneous activity.
The Reticular Formation
The reticular formation is located in the central gray area surrounding the central canal extending throughout the medulla, pons and midbrain. The reticular formation influences autonomic control of respiration, blood pressure and gastrointestinal function. The reticular formation is also important in regulating arousal and sleep.
Information adapted from (51)
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