Organs Brain Sagittal
Superior Sagittal Sinus
This is an unpaired area along the attached margin of the falx cerebri. It allows blood to drain from the lateral aspects of anterior cerebral hemispheres to the confluence of sinuses. Cerebrospinal fluid drains through arachnoid granulations into the superior sagittal sinus and is returned to venous circulation. The superior sagittal sinus is located on the superior border of the falx cerebri and receives blood from superior cerebral, diploic, and emissary veins, as well as receiving CSF via arachnoid granulations. It drains blood from lateral and anterior parts of the cerebrum into the confluence of sinuses. The superior sagittal sinus beings at the foramen cecum and drains into the confluence of sinuses near the internal occipital protuberance. Source
Cingulate Gyrus
The cingulate gyrus is a part of the human brain on the medial aspect of each of the cerebral hemispheres. Along with the parahippocampal gyrus, it makes up the limbic cortex of the brain’s limbic system. As you study the different anatomy topics, you may be feeling a bit overwhelmed, maybe even a little anxious. Ever find yourself fidgeting? Well, that’s your cingulate gyrus helping express your emotional state through gesture, posture and movement. Source
Cingulate Sulcus
The cingulate sulcus is a sulcus (brain fold) on the cingulate cortex in the medial wall of the cerebral cortex. The frontal and parietal lobes are separated from the cingulate gyrus by the cingulate sulcus. It terminates as the marginal sulcus of the cingulate sulcus. It sends a ramus to separate the paracentral lobule from the frontal gyri, the paracentral sulcus. The Cingulate Sulcus is on the medial surface of the hemisphere, it begins below the anterior end of the corpus callosum and runs upward and forward nearly parallel to the rostrum of this body and, curving in front of the genu, is continued backward above the corpus callosum, and finally ascends to the supero-medial border of the hemisphere a short distance behind the upper end of the central sulcus. It separates the superior frontal from the cingulate gyrus. Source
Medial Frontal Gyrus
The medial frontal gyrus is the superior most part of the medial surface of the frontal lobe, which continues onto the superior surface as the superior frontal gyrus. Posteriorly it contains the supplementary motor area. The middle frontal gyrus is a wide gyrus that lies between the superior and the inferior frontal sulci, rostral to the precentral gyrus. The sulci of the middle frontal gyrus have generated a lot of confusion in the anatomical literature. In the anterior part of the middle frontal gyrus lies a deep sulcus that has been referred to as the middle frontal sulcus or the intermediate frontal sulcus. Source
Sulcus of Corpus Callosum
A sulcus found between the superiorly situated cingulate gyrus and the inferiorly located corpus callosum is known as the sulcus of corpus callosum. The corpus callosum, which is the largest pathway of fibers in the brain, is a transverse commissure that connects the left and right hemispheres as well as the roofs of the lateral ventricles. The commissural fibers of the corpus callosum allow for communication between the two cerebral hemispheres to occur. Source
Fornix
The fornix carries some afferent fibres to the hippocampus from structures in the diencephalon and basal forebrain. The fornix is part of the limbic system. While its exact function and importance in the physiology of the brain is still not entirely clear, it has been demonstrated in humans that surgical transection – the cutting of the fornix along its body – can cause memory loss. There is some debate over what type of memory is affected by this damage, but it has been found to most closely correlate with recall memory rather than recognition memory. This means that damage to the fornix can cause difficulty in recalling long-term information such as details of past events, but it has little effect on the ability to recognize objects or familiar situations. Source
Septum Pellucidum
This is a thin, triangular, vertical double membrane separating the anterior horns of the left and right lateral ventricles of the brain. It runs as a sheet from the corpus callosum down to the fornix.
Interventricular Foramen
In the brain, the interventricular foramina are channels that connect the paired lateral ventricles with the third ventricle at the midline of the brain. As channels, they allow cerebrospinal fluid (CSF) produced in the lateral ventricles to reach the third ventricle and then the rest of the brain’s ventricular system. They also contain choroid plexus, a specialized CSF-producing structure, that is continuous with that of the lateral and third ventricles, and which is also present in the fourth ventricle. Source
Interthalamic Adhesion
This is a flattened band of tissue that connects both parts of the thalamus at their medial surfaces. The medial surfaces form the upper part of the lateral wall to the third ventricle. The Interthalamic Adhesion contains nerve cells and nerve fibers. It Connects both parts of the thalamus to their medical surfaces. Source
Thalamus (3rd Ventricle)
It is in the midline, between the left and right lateral ventricles. Running through the third ventricle is the interthalamic adhesion, which contains thalamic neurons and fibers that may connect the two thalami. The third ventricle, like other parts of the ventricular system of the brain, develops from the central neural canal of the neural tube. Specifically, it originates from the portion of the tube that is present in the developing prosencephalon, and subsequently in the developing diencephalon.
Subcallosal (Parolfactory) Area
This is a small area of cortex in each cerebral hemisphere below the genu of the corpus callosum — called also parolfactory area. The subcallosal area (parolfactory area of Broca) is a small triangular field on the medial surface of the hemisphere in front of the subcallosal gyrus, from which it is separated by the posterior parolfactory sulcus, it is continuous below with the olfactory trigone, and above and in front with the cingulate gyrus, it is limited anteriorly by the anterior parolfactory sulcus. Source
Anterior Commissure
The anterior commissure (also known as the precommissure) is a bundle of nerve fibers (white matter), connecting the two temporal lobes of the cerebral hemispheres across the midline, and placed in front of the columns of the fornix. The great majority of fibers connecting the two hemispheres travel through the corpus callosum, which is over 10 times larger than the anterior commissure, and other routes of communication pass through the hippocampal commissure or, indirectly, via subcortical connections. Nevertheless, the anterior commissure is a significant pathway that can be clearly distinguished. The anterior commissure plays a key role in pain sensation, more specifically sharp, acute pain. It also contains decussating fibers from the olfactory tracts, vital for the sense of smell and chemoreception. The anterior commissure works with the posterior commissure to link the two cerebral hemispheres of the brain and also interconnects the amygdalae and temporal lobes, contributing to the role of memory, emotion, speech and hearing. It also is involved in olfaction, instinct, and sexual behavior.
Paraterminal Gyrus
This is a narrow lamina on the medial surface of the hemisphere in front of the lamina terminalis, behind the parolfactory area, and below the rostrum of the corpus callosum. It is continuous around the genu of the corpus callosum with the supracallosal gyrus. It’s also considered a part of limbic system of brain.
Hypothalamic Sulcus
This is a groove in the lateral wall of the third ventricle, marking the boundary between the thalamus and hypothalamus. The upper and lower portions of the lateral wall of the third ventricle correspond to the alar lamina and basal lamina, respectively, of the lateral wall of the fore-brain vesicle and are separated from each other by a furrow, the hypothalamic sulcus, which extends from the interventricular foramen to the cerebral aqueduct.
Lamina Terminalis
The lamina terminalis forms the anterior wall of the third ventricle.
Optic Recess
At the junction of the floor and anterior wall of the third ventricle, immediately above the optic chiasma, the ventricle presents a small angular recess or diverticulum, the optic recess (or supraoptic recess.
Optic Chiasm
This is the part of the brain where the optic nerves partially cross. The optic chiasm is located at the bottom of the brain immediately below the hypothalamus. The optic chiasm is found in all vertebrates, although in cyclostomes (lampreys and hagfishes) it is located within the brain. The crossing over of optic nerve fibres at the optic chiasm allows the visual cortex to receive the same hemispheric visual field from both eyes. Superimposing and processing these monocular visual signals allow the visual cortex to generate binocular and stereoscopic vision. For example, the right visual cortex receives the temporal visual field from the left eye, and the nasal visual field from the right eye, which results in the right visual cortex producing a binocular image of the left hemispheric visual field. The net result of optic nerve crossing over at the optic chiasm is for the right cerebral hemisphere to sense and process left hemispheric vision, and for the left cerebral hemisphere to sense and process right hemispheric vision.
Tuber Cinereum
The tuber cinereum is a hollow eminence of gray matter situated between the mammillary bodies and the optic chiasm. The tuber cinereum is part of the hypothalamus. The tuberomammillary nucleus (TMN) is the sole source of histamine in the brain. Histamine is an organic nitrogenous compound involved in local immune responses, as well as regulating physiological function in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Histamine has as a central role as a mediator of itching.[5] As part of an immune response to foreign pathogens, histamine is produced by basophils and by mast cells found in nearby connective tissues. Histamine increases the permeability of the capillaries to white blood cells and some proteins, to allow them to engage pathogens in the infected tissues.
Hypophysis (Pituitary Gland)
The pituitary gland, or hypophysis, is an endocrine gland about the size of a pea and is situated in a bony hollow, just behind the bridge of your nose. It is attached to the base of your brain by a thin stalk. The hypothalamus, which controls the pituitary by sending messages, is situated immediately above the pituitary gland. The pituitary gland is often called the master gland because it controls several other hormone glands in your body, including the thyroid and adrenals, the ovaries and testicles. It secretes hormones from both the front part (anterior) and the back part (posterior) of the gland. Hormones are chemicals that carry messages from one cell to another through your bloodstream. If your pituitary gland is not producing sufficient amounts of one or more hormones this is called hypopituitarism. The Hypothalamus serves as a communications center for the pituitary gland, by sending messages or signals to the pituitary in the form of hormones which travel via the bloodstream and nerves down the pituitary stalk. These signals, in turn, control the production and release of further hormones from the pituitary gland which signal other glands and organs in the body. The hypothalamus influences the functions of temperature regulation, food intake, thirst and water intake, sleep and wake patterns, emotional behavior and memory. The Hormones secreted from the pituitary gland help control growth, blood pressure, management of energy, all functions of the sex organs, thyroid glands and metabolism as well as some aspects of pregnancy, childbirth, nursing, water/salt concentration at the kidneys, temperature regulation and pain relief. Source
Precuneus
The precuneus is a part of the superior parietal lobule in front of the occipital lobe (cuneus). It is hidden in the medial longitudinal fissure between the two cerebral hemispheres. It is sometimes described as the medial area of the superior parietal cortex. It is involved with episodic memory, visuospatial processing, reflections upon self, and aspects of consciousness. The precuneus is involved in memory tasks, such as when people look at images and try to respond based on what they have remembered in regard to verbal questions about their spatial details. It is involved with the left prefrontal cortex in the recall of episodic memories including past episodes related to the self. The precuneus is also involved in source memory (in which the “source” circumstances of a memory are recalled) with the left inferior prefrontal cortex.
Corpus Callosum
The corpus callosum is Above the Thalamus and under the cortex. The the corpus callosum Connects the right and left hemispheres of the brain The Corpus Callosum is the part of the mind that allows communication between the two hemispheres of the brain. It is responsible for transmitting neural messages between both the right and left hemispheres. Source
Central Sulcus (of Rolando)
The central sulcus is a sulcus, or fold, in the cerebral cortex in the brains of vertebrates. Also called the central fissure, it was originally called the fissure of Rolando or the Rolandic fissure, after Luigi Rolando. It is sometimes confused with the medial longitudinal fissure. The central sulcus is a prominent landmark of the brain, separating the parietal lobe from the frontal lobe and the primary motor cortex from the primary somatosensory cortex. The central sulcus (of Rolando) is a very important landmark in both anatomical and functional neuroanatomy.
Paracentral Lobule
Paracentral lobule is on the medial surface of the hemisphere and is the continuation of the precentral and postcentral gyri. The paracentral lobule controls motor and sensory innervations of the contralateral lower extremity. It is also responsible for control of defecation and urination. Neurons in paracentral lobule are concerned with Motor and sensory innervations of the contralateral lower extremity and Regulation of physiological function such as defecation and micturition.
Precentral Sulcus
The precentral sulcus lies parallel to, and in front of, the central sulcus. (A sulcus is one of the prominent grooves on the surface of the human brain.) The precentral sulcus divides the inferior, middle and superior frontal gyri from the precentral gyrus. In most brains, the precentral sulcus is divided into two parts: the inferior precentral sulcus and the superior precentral sulcus. However, the precentral sulcus may sometimes be divided into three parts or form one continuous sulcus.
Cuneus
The cuneus is a smaller lobe in the occipital lobe of the brain. The cuneus is bounded anteriorly by the parieto-occipital sulcus, inferiorly by the calcarine sulcus. The cuneus (Brodmann area 17) receives visual information from the contralateral superior retina representing the inferior visual field. It is most known for its involvement in basic visual processing.
Habenular Commissure
The habenular commissure, is a brain commissure (a band of nerve fibers) in front of the pineal gland that connects the habenular nuclei on both sides of the diencephalon. The habenular commissure is part of the habenular trigone (a small depressed triangular area situated in front of the superior colliculus and on the lateral aspect of the posterior part of the tænia thalami). The trigonum habenulæ also contains groups of nerve cells termed the ganglion habenulæ. Fibers enter the trigonum habenulæ from the stalk of the pineal gland, and the habenular commissure. Most of the trigonum habenulæ’s fibers are, however, directed downward and form a bundle, the fasciculus retroflexus of Meynert, which passes medial to the red nucleus, and, after decussating with the corresponding fasciculus of the opposite side, ends in the interpeduncular nucleus.
Pineal Body
The pineal gland, also known as the conarium or epiphysis cerebri, is a small endocrine gland in the vertebrate brain. The pineal gland produces melatonin, a serotonin derived hormone which modulates sleep patterns in both circadian and seasonal cycles. The shape of the gland resembles a pine cone, hence its name.
Posterior Commissure
The primary function of the pineal gland is to produce melatonin. Melatonin has various functions in the central nervous system, the most important of which is to help modulate sleep patterns. Melatonin production is stimulated by darkness and inhibited by light. Light sensitive nerve cells in the retina detect light and send this signal to the suprachiasmatic nucleus (SCN), synchronizing the SCN to the day-night cycle. Nerve fibers then relay the daylight information from the SCN to the paraventricular nuclei (PVN), then to the spinal cord and via the sympathetic system to superior cervical ganglia (SCG), and from there into the pineal gland.
Calcarine Sulcus
The calcarine sulcus is a fissure that begins slightly above the occipital pole, usually on the middle surface but at times on the side of the occipital lobe of the brain. It travels along the middle of the cerebrum between the cuneus and the lingual gyrus and is joined by the descending parieto-occipital sulcus. It continues in the lower front of the isthmus of the cingulate gyrus and splenium of the corpus callosum, where it forms the upper boundary of the parahippocampal gyrus for a short distance before it ends. Source
Straight Sinus in Tentorium
The straight sinus, also known as tentorial sinus or the sinus rectus, is an area within the skull beneath the brain that receives venous blood. The straight sinus receives blood from the superior cerebellar veins and inferior sagittal sinus and drains into the confluence of sinuses. It forms from the confluence of the inferior sagittal sinus and great cerebral vein. The straight sinus is an unpaired area beneath the brain which allows blood to drain from the inferior center of the head outwards posteriorly. It receives blood from the inferior sagittal sinus, great cerebral vein, posterior cerebral veins, superior cerebellar veins and veins from the falx cerebri.
Great Cerebral Vein (of Galan)
The vein of Galen, also known as the great cerebral vein or great vein of Galen, is a short trunk formed by the union of the two internal cerebral veins and basal veins of Rosenthal. It lies in the quadrigeminal cistern. It curves backward and upward around the posterior border of the splenium of the corpus callosum to drain into the confluence of the inferior sagittal sinus and the anterior extremity of the straight sinus.
Superior Colliculus
The superior colliculus (Latin, upper hill) is a paired structure of the mammalian midbrain. In other vertebrates the homologous structure is known as the optic tectum or simply tectum. The adjective form tectal is commonly used for mammals as well as other vertebrates. The superior colliculus/optic tectum forms a major component of the midbrain. It is a layered structure, with a number of layers that varies by species. The layers can be grouped into the superficial layers (stratum opticum and above) and the deeper layers (the remaining layers). Neurons in the superficial layers receive direct input from the retina and respond almost exclusively to visual stimuli. Many neurons in the deeper layers also respond to other modalities, and some respond to stimuli in multiple modalities.[1] The deeper layers also contain a population of motor-related neurons, capable of activating eye movements as well as other responses. The general function of the tectal system is to direct behavioral responses toward specific points in egocentric (“body-centered”) space. Each layer contains a topographic map of the surrounding world in retinotopic coordinates, and activation of neurons at a particular point in the map evokes a response directed toward the corresponding point in space. The superior colliculus is involved in preliminary visual processing and control of eye movements. In non-mammalian vertebrates it serves as the main visual area of the brain, functionally analogous to the visual areas of the cerebral cortex in mammals.
Inferior Colliculus
The inferior colliculus (IC) (Latin, lower hill) is the principal midbrain nucleus of the auditory pathway and receives input from several peripheral brainstem nuclei in the auditory pathway, as well as inputs from the auditory cortex. The inferior colliculus is involved in auditory processing. It receives input from various brain stem nuclei and projects to the medial geniculate nucleus of the thalamus, which relays auditory information to the primary auditory cortex.It is involved in the integration and routing of multi-modal sensory perception, mainly the startle response and vestibulo-ocular reflex. It is also responsive to specific amplitude modulation frequencies and this might be responsible for detection of pitch. In addition, spatial localization by binaural hearing is a related function of IC as well.
Quadrigeminal (Rectal) Lamina
The Latin word “tectum” means “roof”. The quadrigeminal plate, also known as the tectal plate or just as tectum, is the portion of the midbrain tectum upon which the superior and inferior colliculi sit. The tectal plate is a region of the brain, specifically the dorsal part of the mesencephalon. This is contrasted with the tegmentum, which refers to the region ventral to the ventricular system. The tectal plate is responsible for auditory and visual reflexes. It is derived in embryonic development from the alar plate of the neural tube. Source
Cerebellum
The cerebellum (Latin for “little brain”) is a major feature of the hindbrain of all vertebrates. In humans, the cerebellum plays an important role in motor control, and it may also be involved in some cognitive functions such as attention and language as well as in regulating fear and pleasure responses, but its movement-related functions are the most solidly established. The human cerebellum does not initiate movement, but contributes to coordination, precision, and accurate timing: it receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine-tune motor activity. Cerebellar damage produces disorders in fine movement, equilibrium, posture, and motor learning. cerebellum has the appearance of a separate structure attached to the bottom of the brain, tucked underneath the cerebral hemispheres. The strongest clues to the function of the cerebellum have come from examining the consequences of damage to it. Animals and humans with cerebellar dysfunction show, above all, problems with motor control, on the same side of the body as the damaged part of the cerebellum. They continue to be able to generate motor activity but lose precision, producing erratic, uncoordinated, or incorrectly timed movements. A standard test of cerebellar function is to reach with the tip of the finger for a target at arm’s length: A healthy person will move the fingertip in a rapid straight trajectory, whereas a person with cerebellar damage will reach slowly and erratically, with many mid-course corrections.
Superior Medullary Velum
The superior medullary velum is a thin, transparent lamina of white matter, which stretches between the superior cerebellar peduncles; on the dorsal surface of its lower half the folia and lingula are prolonged. It forms, together with the superior cerebellar peduncle, the roof of the upper part of the fourth ventricle, it is narrow above, where it passes beneath the facial colliculi, and broader below, where it is continuous with the white substance of the superior vermis. A slightly elevated ridge, the fraenulum veli, descends upon its upper part from between the inferior colliculi, and on either side of this the trochlear nerve emerges. Blood is supplied by branches from the superior cerebellar artery. Source
4th Ventricle and Choroid Plexus
The choroid plexus of the fourth ventricle consists of two symmetrical parts located in the roof of the ventricle and protruding through its openings, the foramina of Luschka and Magendie. The arteries supplying the choroid plexus of the fourth ventricle are difficult to approach because of their deep location within the cerebellopontine angles and the cerebellomedullary fissure. They originate from multiple sites on the cerebellar arteries and pass near the vital structures of the pons and medulla. The choroid plexus is a plexus of cells that produces the cerebrospinal fluid in the ventricles of the brain. The choroid plexus consists of modified ependymal cells. In addition to CSF production, the choroid plexus act as a filtration system, removing metabolic waste, foreign substances, and excess neurotransmitters from the CSF. In this way the choroid plexus has a very important role in helping to maintain the delicate extracellular environment required by the brain to function optimally. Source
Inferior Medullary Velum
The inferior medullary velum (posterior medullary velum) is a thin layer of white substance, prolonged from the white center of the cerebellum, above and on either side of the nodule, it forms the infero-posterior part of the fourth ventricle. its convex edge is continuous with the white substance of the cerebellum, while its thin concave margin is apparently free, in reality, however, it is continuous with the epithelium of the ventricle, which is prolonged downward from the posterior medullary velum to the taeniae.
Medulla Oblongata
The medulla oblongata (or medulla) is located in the brainstem, anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involuntary) functions ranging from vomiting to sneezing. The medulla contains the cardiac, respiratory, vomiting and vasomotor centers and therefore deals with the autonomic functions of breathing, heart rate and blood pressure. The medulla oblongata connects the higher levels of the brain to the spinal cord, and is responsible for several functions of the autonomous nervous system which include the control of ventilation via signals from the carotid and aortic bodies. Respiration is regulated by groups of chemoreceptors. These sensors detect changes in the acidity of the blood; if, for example, the blood becomes too acidic, the medulla oblongata sends electrical signals to intercostal and phrenical muscle tissue to increase their contraction rate and increase oxygenation of the blood. The ventral respiratory group and the dorsal respiratory group are neurons involved in this regulation. The pre-Bötzinger complex is a cluster of interneurons involved in the respiratory function of the medulla. Also, our reflex centers of vomiting, coughing, sneezing, and swallowing. These reflexes which include the pharyngeal reflex, the swallowing reflex (also known as the palatal reflex), and the masseter reflex can be termed, bulbar reflexes.
Cerebral Peduncle
The cerebral peduncle is made of a mass of nerve fibers, and there is one peduncle on each side of the brain. The term ‘cerebral’ means it is related to the brain. A ‘peduncle’ is a stem-like connector. The cerebral peduncles are connected to the pons, which is a part of the frontal brain stem that looks like a swelling. Many other nerve bundles also connect to the pons. Cerebral peduncles help transport nerve impulses from the higher part of the brain (cortex) and the brain stem, or lower part of the brain, to other areas of the central nervous system. The cerebral peduncles help refine our movements. If body movement impulses came straight from the cortex, the movements would seem erratic and clumsy. The peduncles adjust the commands by taking into account where the body parts currently are located before directing the movement, and they sometimes slow down the movement. When there is an injury to cerebral peduncles, the symptoms of the injury show up in the part of the body related to the injured peduncle. Source
Pons
The pons is a portion of the brain stem, located above the medulla oblongata and below the midbrain. Although it is small, at approximately 2.5 centimeters long, it serves several important functions. It is a bridge between various parts of the nervous system, including the cerebellum and cerebrum, which are both parts of the brain. There are many important nerves that originate in the pons. The trigeminal nerve is responsible for feeling in the face. I also controls the muscles that are responsible for biting, chewing, and swallowing. The abducens nerve allows the eyes to look from side to side. The facial nerve controls facial expressions, and the vestibulocochlear nerve allows sound to move from the ear to the brain. All of these nerves start within the pons. As part of the brain stem, the pons also impacts several automatic functions necessary for life. A section of the lower pons stimulates and controls the intensity of breathing, and a section of the upper pons decreases the depth and frequency of breaths. The pons has also been associated with the control of sleep cycles. Source
Choroid Plexus of 3rd Ventricle
The choroid plexus is a plexus of cells that produces the cerebrospinal fluid in the ventricles of the brain. The choroid plexus consists of modified ependymal cells. In addition to CSF production, the choroid plexus act as a filtration system, removing metabolic waste, foreign substances, and excess neurotransmitters from the CSF. In this way the choroid plexus has a very important role in helping to maintain the delicate extracellular environment required by the brain to function optimally. The third ventricle is one of the four CSF-filled cavities that together comprise the ventricular system. The third ventricle is a median cleft between the two thalami and is bounded laterally by them and the hypothalamus. Its anterior wall is formed by the lamina terminalis, and posteriorly there is the pineal recess. Source
Stria Medullaris of Thalamas
The stria medullaris is a part of the epithalamus. It is a fiber bundle containing afferent fibers from the septal nuclei, lateral preoptico-hypothalamic region, and anterior thalamic nuclei to the habenula. It forms a horizontal ridge on the medial surface of the thalamus and is found on the border between dorsal and medial surfaces of thalamus. Superior and lateral to habenular trigone.
Peri Occipital Sulcus
The parieto-occipiatal lobe has been found in various neuroimaging studies, including PET (positron-emission-tomography) studies, and SPECT (single-photon emission computed tomography) studies, to be involved along with the dorsolateral prefrontal cortex during planning.