Septum Pellucidum: A triangular double membrane separating the anterior horns of the LATERAL VENTRICLES of the brain. It is situated in the median plane and bounded by the CORPUS CALLOSUM and the body and columns of the FORNIX (BRAIN).Septo-Optic Dysplasia: A condition resulting from congenital malformations involving the brain. The syndrome of septo-optic dysplasia combines hypoplasia or agenesis of the SEPTUM PELLUCIDUM and the OPTIC NERVE. The extent of the abnormalities can vary. Septo-optic dysplasia is often associated with abnormalities of the hypothalamic and other diencephalic structures, and HYPOPITUITARISM.Ballistocardiography: Technique of graphic representation of the movements of the body imparted by the ballistic forces (recoil and impact) associated with cardiac contraction and ejection of blood and with the deceleration of blood flow through the large blood vessels. These movements, quantitatively very minute, are translated by a pickup device (transducer) into an electrical potential which is suitably amplified and recorded on a conventional electrocardiograph or other recording machine.Cerebral Ventricle Neoplasms: Neoplasms located in the brain ventricles, including the two lateral, the third, and the fourth ventricle. Ventricular tumors may be primary (e.g., CHOROID PLEXUS NEOPLASMS and GLIOMA, SUBEPENDYMAL), metastasize from distant organs, or occur as extensions of locally invasive tumors from adjacent brain structures.Hydrocephalus: Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, INTRACRANIAL HYPERTENSION; HEADACHE; lethargy; URINARY INCONTINENCE; and ATAXIA.Ventriculostomy: Surgical creation of an opening in a cerebral ventricle.Third Ventricle: A narrow cleft inferior to the CORPUS CALLOSUM, within the DIENCEPHALON, between the paired thalami. Its floor is formed by the HYPOTHALAMUS, its anterior wall by the lamina terminalis, and its roof by EPENDYMA. It communicates with the FOURTH VENTRICLE by the CEREBRAL AQUEDUCT, and with the LATERAL VENTRICLES by the interventricular foramina.Cerebral Ventricles: Four CSF-filled (see CEREBROSPINAL FLUID) cavities within the cerebral hemispheres (LATERAL VENTRICLES), in the midline (THIRD VENTRICLE) and within the PONS and MEDULLA OBLONGATA (FOURTH VENTRICLE).Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Panic Disorder: A type of anxiety disorder characterized by unexpected panic attacks that last minutes or, rarely, hours. Panic attacks begin with intense apprehension, fear or terror and, often, a feeling of impending doom. Symptoms experienced during a panic attack include dyspnea or sensations of being smothered; dizziness, loss of balance or faintness; choking sensations; palpitations or accelerated heart rate; shakiness; sweating; nausea or other form of abdominal distress; depersonalization or derealization; paresthesias; hot flashes or chills; chest discomfort or pain; fear of dying and fear of not being in control of oneself or going crazy. Agoraphobia may also develop. Similar to other anxiety disorders, it may be inherited as an autosomal dominant trait.Fetal Diseases: Pathophysiological conditions of the FETUS in the UTERUS. Some fetal diseases may be treated with FETAL THERAPIES.Ultrasonography, Prenatal: The visualization of tissues during pregnancy through recording of the echoes of ultrasonic waves directed into the body. The procedure may be applied with reference to the mother or the fetus and with reference to organs or the detection of maternal or fetal disease.