Temporal cortex

Fig. 4. Tyrosine hydroxylase immunoreactivity (TH-IR) in the human brain at the level of the posterior striatum (taken from Sutoo et al., 2001). Note highest TH-IR in the caudate (CN) and putamen (Pu), but significant levels are also evident in other brain regions such as the globus pallidus (external GPe and internal GPi), cerebral cortex temporal (T) superior frontal (SF), hippocampus (Hipp) and amygdala (Amy).

For the majority of cases of individual discrimination and recognition, it is likely that the main olfactory system is the primary system involved and that higher-order olfactory processing areas are essential. Thus one would expect that projection areas of the main olfactory system should be involved in individual discrimination. Recent neurophysiological studies of the anterior piriform cortex indicate a role for this region in discrimination of learned odors, including odors of mixtures (Wilson, 2002 Wilson and Stevenson, 2003). In one set of lesion studies we showed that one area that may be important for discrimination of individual odors is the lateral entorhinal cortex and the surrounding para-hippocampal area (peri-rhinal cortex, temporal cortex, and subiculum). 

The temporal lobe is the inferior middle portion of the cerebral cortex of both hemispheres. The temporal lobes are involved in the analysis of visual and acoustic information and in memory formation. The hippocampus is part of the inner, medial side of the temporal lobes. 

While there are some reports of increased NMDA and non-NMDA receptor number in various cortical regions of schizophrenics including the prefrontal cortex, there are also indications of impaired glutamate innervation, such as reduction in its neuronal uptake sites (Ishimaru, Kurumaji and Torn 1994). Also it has been found that levels of the mRNA for the NRI subunit of the NMDA receptor in the hippocampus and its D-aspartate binding sites in the temporal cortex are both reduced more on the left than right side in schizophrenic brain. This is another indication of greater malfunction on the left side of the brain and the possibility that some schizophrenic symptoms arise from an imbalance between cross-cortical activity. 

Named for the bones of the cranium under which they lie, the lobes are conspicuously defined by prominent sulci of the cortex, which have a relatively constant position in human brains. Each lobe is specialized for different activities (see Figure 6.3). Located in the anterior portions of the hemispheres, the frontal lobes are responsible for voluntary motor activity, speaking ability, and higher intellectual activities. The parietal lobes, which are posterior to the frontal lobes, process and integrate sensory information. The occipital lobes, located in the posterior-most aspects of the cerebrum, process visual information, and the temporal lobes, located laterally, process auditory information. 

Textbooks on neuroscience often describe the location and function of hundreds of individual brain regions (see references above). However, for current purposes these will be kept to a minimum (Figure 2.1). Anatomically, the brain can be subdivided into the forebrain containing the telencephalon and diencephalon, the midbrain or mesencephalon and the hindbrain (metencephalon and myelencephalon). The telencephalon includes the left and right cerebral hemispheres encompassed by the cerebral cortex (neocortex). Cortex is a translation of the word bark and is so-called because its surface, made up of numerous sulci (grooves or invaginations) and gyri (raised areas), is on the outer surface of the brain like the bark of a tree. Each hemisphere is divided into four lobes, named from the front (rostral) to back (caudal) of the brain frontal, temporal, parietal and occipital. 

LTP has been shown in many parts of the brain but it has been most extensively studied in the hippocampus, a phy-logenetically old part of the cerebral cortex that in humans is embedded in the temporal horn and in rats and rabbits lies beneath the parietal and temporal neocortex (Fig. 15-3A). The hippocampus is essential for (declarative) memory formation in rats the role of hippocampus in acquisition of spatial information has been studied in... 

Frontotemporal dementias occur as familial forms and, more commonly, as sporadic diseases. They are characterized by a remarkably circumscribed atrophy of the frontal and temporal lobes of the cerebral cortex, often with additional, subcortical changes. In 1994, an autosomal-dominantly inherited form of frontotemporal dementia with parkinsonism was linked to chromosome 17q21.2. Subsequently, other forms of frontotemporal dementia were linked to this region, resulting in the denomination frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) for this class of disease. All cases of FTDP-17 have so far shown a filamentous pathology made of hyperphosphorylated tau protein (Fig. 45-7). In 1998, mutations in tau were reported in FTDP-17 patients [29-31]. Since then, more than 30 different mutations have been described in over 80 families with FTDP-17 (Fig. 45-6). 

Amnesia patients showed the role of temporal lobe in memory. Almost at the same time of Penfield s studies, Brenda Milner of the Montreal Neurological Institute examined a patient, known by his initials as H. M., who had undergone bilateral surgical removal of the temporal lobe (medial temporal cortex, amygdala, and two-thirds of the hippocampus). The surgery was apparently a success... 

Multinuclear MRS studies have demonstrated alterations in brains of schizophrenic patients. Phosphorus MRS studies, looking at both first-onset-unmedicated and chronic-medicated schizophrenia, consistently report alterations in the phospholipid profile in the frontal and temporal cortex [26-30]. Typically, phosphomonoester (PME) levels are lower than in controls, and phosphodiesters... 

H. Sato, T. Takeuchi, and K. Sakai. Temporal cortex activation during speech recognition an optical topography study. Cognition, 40 548-560, 1999. 

The cerebrum is composed of four lobes covered by cerebral cortex frontal, parietal, temporal, and occipital (figure 2.9). The cortical surface... 

Frontotemporal dementia involves an early and primary degenerative process of frontal and/or temporal cortex. Several disorders fall under this rubric, such as Pick s disease and the dementia associated with amyotrophic lateral sclerosis (ALS). ALS is a degenerative disease of upper motor neurons that is sometimes accompanied by a frontal lobe dementia (Vercelletto et al. 1999 Abe et al. 1997). ALS has been associated with mutations in the free radical scavenging enzyme superoxide dismutase 1 (Price et al. 1997). Pick s disease is associated histologically with a loss of neurons and cytoplasmic Pick bodies in surviving neurons. 

---