|Brain: Superior frontal gyrus
| Superior frontal gyrus of the human brain.
| Coronal section through anterior cornua of lateral ventricles.
|| gyrus frontalis superior
|| subject #189 821
| Part of
|| Frontal lobe
|| Anterior cerebral
The superior frontal gyrus makes up about one-third of the frontal lobe of the human brain. It is bounded laterally by the superior frontal sulcus.
The superior frontal gyrus, like the inferior frontal gyrus and the middle frontal gyrus, is more of a region than a true gyrus.
In fMRI experiments, Goldberg et al. have found evidence that the superior frontal gyrus is involved in self-awareness, in coordination with the action of the sensory system.
In 1998, neurosurgeon Itzak Fried described a 16-year-old female patient (referred to as "patient AK") who laughed when her SFG was stimulated with electric current during treatment for epilepsy. Electrical stimulation was applied to the cortical surface of AK's left frontal lobe while an attempt was made to locate the focus of her epileptic seizures (which were never accompanied by laughter).
Fried identified a 2 cm by 2 cm area on the left SFG where stimulation produced laughter consistently (over several trials). AK reported that the laughter was accompanied by a sensation of merriment or mirth. AK gave a different explanation for the laughter each time, attributing it to an (unfunny) external stimulus. Thus, laughter was attributed to the picture she was asked to name (saying "the horse is funny"), or to the sentence she was asked to read, or to persons present in the room ("you guys are just so funny... standing around").
Increasing the level of stimulation current increased the duration and intensity of laughter.
For example, at low currents only a smile was present, while at higher currents a louder, contagious laughter was induced. The laughter was also accompanied by the stopping of all activities involving speech or hand movements.
- ^ Goldberg I, Harel M, Malach R (2006). "When the brain loses its self: prefrontal inactivation during sensorimotor processing". Neuron 50 (2): 329-39. PMID 16630842.
- ^ Watching the brain 'switch off' self-awareness at newscientist.com
- ^ Fried I, Wilson C, MacDonald K, Behnke E (1998). "Electric current stimulates laughter". Nature 391 (6668): 650. PMID 9490408.
|Brain: telencephalon (cerebrum, cerebral cortex, cerebral hemispheres)|
|Primary sulci/fissures||Medial longitudinal, Lateral, Central, Parietoöccipital, Calcarine, Cingulate, Callosal Collateral fissure|
|Frontal lobe||Precentral gyrus (Primary motor cortex, 4), Precentral sulcus, Superior frontal gyrus/Frontal eye fields (6, 8, 9), Middle frontal gyrus (46), Inferior frontal gyrus (44-Pars opercularis, 45-Pars triangularis), Orbitofrontal cortex (10, 11, 12, 47)|
|Parietal lobe||Somatosensory cortex (Primary (1, 2, 3, 43), Secondary (5)), Precuneus (7m), Parietal lobules (Arcuate fasciculus/Superior (7l), Inferior (40)), Angular gyrus (39), Intraparietal sulcus, Marginal sulcus|
|Occipital lobe||Primary visual cortex (17), Cuneus, Lingual gyrus, 18, 19 - Lateral occipital sulcus|
|Temporal lobe||Primary auditory cortex (41, 42), Superior temporal gyrus (38, 22), Middle temporal gyrus (21), Inferior temporal gyrus (20), Fusiform gyrus (37) Medial temporal lobe (Amygdala, Hippocampus, Parahippocampal gyrus (27, 28, 34, 35, 36)|
|Cingulate cortex/gyrus||Subgenual area (25), anterior cingulate (24, 32, 33), Posterior cingulate (23, 31), Retrosplenial cortex (26, 29, 30), Supracallosal gyrus|
|white matter tracts||Corpus callosum (Splenium, Genu, Rostrum, Tapetum), Septum pellucidum, Internal capsule, Corona radiata, External capsule, Olfactory tract, Fornix (Commissure of fornix), Anterior commissure, Posterior commissure Terminal stria Superior and Inferior longitudinal fasciculus, uncinate fasciculus, cingulum, Inferior occipitofrontal fasciculus|
|Basal ganglia||Striatum (Putamen,Caudate nucleus, Nucleus accumbens), Globus pallidus, Claustrum, Subthalamic nucleus, Substantia nigra|
|Other||Insular cortex Olfactory bulb, Anterior olfactory nucleus Septal nuclei Basal optic nucleus of Meynert|
|Some categorizations are approximations, and some Brodmann areas span gyri.|