The amygdala is located deep in the medial temporal lobe, and has reciprocal connections with many regions of the cortex, such as prefrontal and cingulate cortex, as well as sub-cortical regions such as the brainstem and hippocampus. The amygdala is implicated in the processing and memory of emotional responses, particularly emotional learning, as well as mediating the autonomic expression of emotion.

What is the evidence for amygdala alterations?

Moderate to high quality evidence found reduced grey matter volume in the amygdala and the amygdala-hippocampus region of people with schizophrenia compared to controls. There were also reductions in the amygdala of first-episode patients and relatives of people with schizophrenia.

Compared to people with bipolar disorder, moderate to low quality evidence finds a medium-sized effect of reduced amygdala volume in people with schizophrenia.

Moderate quality evidence found people with schizophrenia showed increased activity in the amygdala during executive function tasks, and increased or decreased activity during emotion processing tasks.

October 2020

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The arcuate fasciculus is a bundle of axons that connects the temporal cortex and inferior parietal cortex to locations in the frontal lobe. One of the key roles of the arcuate fasciculus is connecting Broca’s and Wernicke’s areas, which are involved in producing and understanding language. Therefore, there may be anomalies in the arculate fasciculus of people with schizophrenia who experience auditory-verbal hallucinations.

What is the evidence for changes in the arculate fasciculus?

Moderate quality evidence found reduced white matter integrity in the bilateral arcuate fasciculus, including bilateral anterior and posterior segments, and the left long segment.

There was reduced white matter integrity in the left, but not the right arcuate fasciculus in people with schizophrenia who experience auditory-verbal hallucinations.

October 2020

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The basal ganglia is a group of sub-cortical nuclei thought to be involved in motor control and learning. The nuclei comprising the basal ganglia include the caudate, putamen, globus pallidus, the subthalamic nucleus, and the substantia nigra. The caudate and putamen together form the striatum, while the globus pallidus and the putamen together form the lenticular nucleus. The striatum is the principal input centre, receiving afferents primarily from the cortex, but also from the substantia nigra, thalamus, and external globus pallidus. There are two primary pathways from the striatum through the basal ganglia (‘direct’ and ‘indirect’), which incorporate different components of the basal ganglia circuitry, and play different roles in controlling and planning movements and cognition.

What is the evidence for basal ganglia alterations?

Structural changes

Moderate to high quality evidence found increased globus pallidus volume in medicated people with schizophrenia compared to controls. In mediation-naïve patients, the caudate nucleus was reduced. Moderate quality evidence found increases in the left caudate head of people with schizophrenia, but decreases in the left caudate head in those with persistent negative symptoms.

In people with first-episode schizophrenia, there was decreased grey matter in the bilateral caudate head (but not nucleus) and increased grey matter in the left putamen compared to controls. There was also increased grey matter in the left putamen of people with schizophrenia (not necessarily first-episode) compared to relatives of people with schizophrenia. Moderate to low quality evidence found greater reductions in the bilateral caudate in first-episode treatment-naïve patients (vs. controls) than in first episode treated patients (vs. controls). Moderate to high quality evidence suggests increased antipsychotic use was associated with increased basal ganglia volume over time (>2 years).

Moderate to low quality evidence found similar grey matter volume decreases in the right putamen in people with schizophrenia and people with an autistic spectrum disorder compared to controls.

Functional changes

Moderate quality evidence found reduced activity in the right putamen of people with schizophrenia during executive functioning and timing tasks compared to controls. Moderate quality evidence found increased activations in the left putamen of people with schizophrenia compared to controls during emotionally neutral tasks.

Moderate to low quality evidence finds increased activation in the right caudate of relatives of people with schizophrenia compared to controls during cognitive tasks, and increased activation in the left lentiform nucleus during emotion tasks.

Moderate quality evidence finds unmedicated people with schizophrenia have a medium to large increase in choline in the basal ganglia. Moderate to low quality evidence found no differences in D2/D3 receptor availability in the substantia nigra of unmedicated people with schizophrenia compared to controls, and no differences in GABA levels in the striatum of people with schizophrenia.

Structural and functional changes

Moderate quality evidence found decreased grey matter volume and decreased functional activity in the left caudate nucleus of drug-free first-episode patients.

October 2020

The post Basal ganglia appeared first on NeuRA Library.

Maintenance of an adequate pH balance in all tissues and organs is important for good health. Decreased levels of brain pH are associated with increased levels of lactate, and vise versa. Lactate is an acidic source of fuel that is constantly generated and consumed in the brain. An imbalance in pH, particularly a shift toward high acidity, is associated with numerous physical and mental disorders.

What is the evidence for brain pH and lactate in people with schizophrenia?

Moderate quality evidence suggests no significant differences in brain pH between people with schizophrenia and controls. Lower quality evidence is unclear of changes in lactate concentrations.

October 2020

The post Brain pH and lactate appeared first on NeuRA Library.

Brain weight refers to the basic mass measurement of a post-mortem brain, either at time of autopsy (‘fresh’) or after formalin fixation (‘fixed’). Its ease of collection means it is a routine measurement at autopsy and has become a widely used tool for insight into brain integrity. If brain weight is altered, this provides a non-specific indication of neuropathology. It is often a presumed equivalent of the MRI findings of decreased brain volume.

What is the evidence for brain weight?

Moderate quality evidence suggests the brain of a person with schizophrenia is significantly lower in weight than a healthy brain. Moderate quality evidence suggests that male brain weight is significantly inversely correlated with age at disease onset, such that an earlier age at onset indicated a heavier brain weight.

October 2020

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Pending enough primary studies, we invite reviews on this topic to be conducted. Alternatively we will endeavour to conduct our own review to fill this gap in the Library.

October 2020

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The cerebellum sits below the larger cerebrum of the brain, and is connected via the brainstem. The cerebellum is divided into two hemispheres separated dorsally by a midline zone called the vermis. It contains three primary lobes, the flocculonodular lobe, anterior lobe, and posterior lobe. Broadly, the cerebellum is thought to function in fine motor control (coordination and precision) and motor learning, balance, posture, as well as some cognitive and emotional capacity. The interaction of sensory, cognitive and motor functions may also contribute to proprioception (the awareness of self in space), planning movements, and evaluating information for action. The detailed functions of each region of the cerebellum are determined largely by their connectivity.

What is the evidence for cerebellum alterations?

Structural changes

Moderate quality evidence found grey matter reductions in the bilateral cerebellum of people with schizophrenia, particularly in medication-naïve patients, compared to controls. There were also white matter reductions in the bilateral cortico-ponto-cerebellum tract, and in the bilateral inferior and superior cerebellar penduculus. High quality evidence found no

Moderate to high quality evidence found better overall functioning was associated with larger cerebellum volume, and moderate to low quality evidence found reduced white matter volume in the cerebellum was associated with increased severity of neurological soft signs.

Functional changes

Moderate to high quality evidence found decreased functional activity in the right cerebellum (lobule VIII and crus I) and the left cerebellum (lobule IX), with no increases in functional activity. Functional connectivity strength was decreased in the left cerebellum (lobule IV/V) extending to the left fusiform gyrus (BA 30), and increased in the left cerebellum (crus I/II) of medication-naïve patients with first-episode schizophrenia compared to controls. Moderate to low quality evidence found increased activity in the cerebellum during auditory hallucinations in people with schizophrenia.

Moderate quality evidence found decreased functional activity in the left cerebellum of people with schizophrenia (vs. controls) during episodic memory retrieval. There was reduced activity in the right cerebellum lobule VI during explicit threat processing, and decreased activity in the fusiform gyrus extending into the cerebellum lobule IV/VI during implicit threat processing. There was decreased activity in the cerebellum during reward anticipation tasks. There was increased activity in the cerebellum during facial emotion recognition. Moderate to low quality evidence found decreased functional activity in the cerebellum of first- degree relatives of people with schizophrenia (compared to controls) during working memory and executive functioning, but not during cognitive control, long-term memory, or language processing.

Moderate quality evidence found decreased metabolic N-acetyl aspartate in the cerebellum of people with schizophrenia compared to controls.

Structural and functional changes

Moderate quality evidence found increased grey matter volume and decreased functional activity in the left cerebellum, and increased grey matter volume and increased functional activity in the left cerebellum lobule IX.

October 2020

The post Cerebellum appeared first on NeuRA Library.

Pending enough primary studies, we invite reviews on this topic to be conducted. Alternatively we will endeavour to conduct our own review to fill this gap in the Library.

October 2020

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The cingulate cortex is part of the medial frontal cortex, located immediately dorsal to the corpus callosum along the sagittal midline. The anterior cingulate cortex has three key divisions which may be functionally distinct (dorsal, rostral, subcallosal). The dorsal part of the anterior cingulate cortex has reciprocal connections with the prefrontal and parietal cortices as well as the frontal eye fields, and plays a primary role in balancing top-down and bottom-up processing of external stimuli; that is, monitoring behaviour and incoming stimuli in the context of current goals, and assigning control to other areas in the brain when required. By contrast, the ventral (rostral and subcallosal) parts of the anterior cingulate cortex are connected with amygdala, nucleus accumbens, hypothalamus, and insula, and are implicated in assessing the salience of sensory information, and regulating emotion and autonomic activity.

What is the evidence for cingulate cortex anomalies?

Structural changes

Moderate to high quality evidence found reductions in grey and white matter in bilateral regions of the cingulate cortex of people with schizophrenia. Specifically, there were grey matter reductions in the anterior and posterior cingulate gyrus of people with schizophrenia and reduced grey matter in the left anterior cingulate/paracingulate gyrus and right dorsal anterior cingulate of first-episode patients. High-risk individuals showed decreases in bilateral median cingulate and the right anterior cingulate gyrus compared to controls and increases in the left anterior cingulate compared to first-episode patients.

Functional changes

Moderate quality evidence found decreased activity in the posterior cingulate cortex of people with schizophrenia at rest compared to controls. There was under-activation in the anterior and middle cingulate cortex of people with schizophrenia during attention and inhibition tasks, and over-activation in the anterior cingulate cortex during working memory tasks. During executive functioning, there was increased activity in the left cingulate gyrus and decreased activity in right cingulate gyrus. During cognitive control, there was decreased activity in the bilateral anterior cingulate/paracingulate gyrus. During auditory stimulation, there was decreased activation in the anterior cingulate cortex, and during theory of mind tasks, there was decreased activity in the left cingulate gyrus. During reward anticipation tasks there was reduced activation in the right median cingulate/paracingulate gyri. In relatives of people with schizophrenia, there was decreased activity in the left cingulate gyrus during executive functioning and working memory tasks compared to controls.

Moderate quality evidence found decreased N-acetylaspartate and N-acetylaspartate/creatine ratio in the anterior cingulate gyrus of people with schizophrenia and their first-degree relatives. High quality evidence finds a small decrease in glutathione in the anterior cingulate of people with schizophrenia.

Structural and functional changes

Moderate to high quality evidence found decreased grey matter volume and decreased functional activity in the left medial posterior cingulate/paracingulate gyrus in drug-free, first-episode patients. Moderate quality evidence found decreased grey matter volume and decreased functional activation in the right medial frontal/anterior cingulate, and decreased grey matter volume and increased functional activation in the left medial frontal/anterior cingulate of people with first-episode schizophrenia, regardless of medication status.

Moderate quality evidence finds decreased activation in the bilateral anterior cingulate and left posterior cingulate of people with schizophrenia compared to people with an autism spectrum disorder during facial emotion recognition tasks. During theory of mind tasks, there was increased activation in the left posterior cingulate cortex in people with schizophrenia compared to people with an autism spectrum disorder. Moderate to low quality evidence found similar grey matter volume decreases in the right posterior cingulate cortex of people with schizophrenia and people with an autism spectrum disorder.

October 2020

The post Cingulate cortex appeared first on NeuRA Library.

The claustrum is a thin irregular sheet of grey matter located sagitally between the external capsule and the extreme capsule fibre tracts. The connectivity of the claustrum has not been extensively determined, however it appears to have connections with almost all cortical regions, as well as some subcortical connections such as the hippocampus, amygdala and basal ganglia. The function of the claustrum is also largely unclear, but may be involved in some functions of the neighbouring insula. The widespread connectivity of the claustrum places it in a prime position for multimodal integration and processing of perceptual, cognitive and motor capacities. Definitive understanding of the function of the claustrum is somewhat limited by the spatial resolution of current imaging technologies. Likewise, singular inactivation of the claustrum (whether pharmacologically or surgically) for inferring function is difficult, as the claustrum is at most only a few millimetres wide.

What is the evidence for claustrum alterations?

Moderate quality evidence found greater reduction in the right claustrum in people with treatment naïve, first-episode schizophrenia compared to people with treated first-episode schizophrenia or compared to people without schizophrenia. People with schizophrenia also showed reduced functional activity in the bilateral claustrum during executive function tasks compared to people without schizophrenia.

October 2020

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