[Geriatric psychiatry--relevance for the general practitioner]. / Gerontopsychiatrie--Relevanz für den Allgemeinpraktiker.

The older population, the group of the very old in particular, is increasing and thus the risk group for the two most important psychiatric disorders, dementia and depression. Many individuals become mentally ill for the first time late in life, mainly because of losses, loneliness and somatic diseases. Therefore, beside physical examination, screening for depression and cognitive testing are very important for the general practitioner. Relatives and caregivers often play a keyrole. They have to be involved in evaluation and therapy and their needs for support and advice should be considered.

Localization and responses of neurones in the parieto-insular vestibular cortex of awake monkeys (Macaca fascicularis).

1. In four Java monkeys (Macaca fascicularis) 152 vestibular neurones were recorded in the parietal cortex located in the upper bank of the lateral sulcus near the posterior end of the insula. We called this region parieto-insular vestibular cortex (PIVC). PIVC extends about 6-8 mm in the anterior-posterior direction from the posterior part of the insula into the retroinsular region (stereotaxic co-ordinates: anterior 4-12 mm, lateral 16-19 mm and vertical 3-6 mm). 2. About two-thirds of the neurones recorded from this region responded to vestibular stimuli; the non-vestibular neurones responded predominantly to somatosensory stimulation of the neck and shoulder region. The PIVC area is a polysensory field, since almost all vestibular neurones were also activated by somatosensory and visual stimuli. Large-field optokinetic stimulation was the most effective visual stimulus. 3. With vestibular stimuli, responses to angular acceleration were dominant; steady tilt in darkness rarely led to any change in neuronal spontaneous activity. Of sixty-four neurones tested by rotation in more than one plane, fifty-four responded to excitation of semicircular canal receptors aroused by rotation in more than one of the three experimental planes (roll, yaw, pitch). Compared with vestibular brain stem units PIVC neurones discharged with a higher variability. 4. In the responses to horizontal rotation of the animal 38% type I, 53% type II and 9% type III units were recorded (classification according to Duensing & Schaefer, 1958). The gain measured with horizontal sinewave rotation was lower by a factor of about 4 in PIVC neurones as compared with the responses of vestibular neurones in the brain stem or thalamus (VPL). The phase response characteristics and the gain increase with increasing sinewave stimulus frequency, however, were in the same range as observed in neurones of the afferent vestibular system. 5. When the vestibular responses to sinusoidal rotation were tested in all three experimental planes (yaw, roll, pitch), the response strength as expressed by the amplitude of the peristimulus time histograms (PSTHs) differed for the three rotational planes. For different units the relative sensitivity to rotation in each of the three planes also differed. We concluded from this observation that different PIVC units had different optimum sensitivity planes for rotation with respect to the head co-ordinates, whereby all possible planes are represented.

Vestibular neurones in the parieto-insular cortex of monkeys (Macaca fascicularis): visual and neck receptor responses.

1. One hundred and fifty-two vestibularly activated neurones were recorded in the parieto-insular vestibular cortex (PIVC) of four awake Java monkeys (Macaca fascicularis): sixty-two were tested systematically with visual stimulation and seventy-nine were tested with various somatosensory stimuli. With very few exceptions all vestibular neurones tested responded to visual and somatosensory stimulation, therefore being classified as polymodal vestibular units. 2. A most effective stimulus for all fifty-eight visually activated PIVC units was movement of a large structured visual pattern in an optimal direction. From forty-four units responsive to a horizontally moving optokinetic striped drum, twenty-nine were activated with optokinetic movement in the opposite direction to the activating vestibular stimulus ('synergistic' response), thirteen were activated optokinetically and vestibularly in the same direction ('antagonistic' responses) and two were biphasic. The gain of the optokinetic response to sinusoidal stimulation (average 0.28 (impulses s-1) (deg s-1)-1 at 0.2 Hz, 56 deg amplitude) was in a range similar to that of the vestibular gain at low frequencies. At 1 Hz some units only showed weak optokinetic responses or none at all, but the vestibular response was still strong. 3. With different 'conflicting' or 'enhancing' combinations of optokinetic and vestibular stimulation no generalized type of interaction was observed, but the responses varied from nearly 'algebraic' summation to no discernible changes in the vestibular responses by additional optokinetic stimuli. With all visual-vestibular stimulus combinations the responses to the vestibular stimulus remained dominant. 4. The optokinetic preferred direction was not related to gravitational coordinates since the optokinetic responses were related to the head co-ordinates and remained constant with respect to the head co-ordinates at different angles of steady tilt. 5. Almost all PIVC units were activated by somatosensory stimulation, whereby mainly pressure and/or movement of neck and shoulders (bilateral) and movement of the arm joints elicited vigorous responses. Fewer neurones were activated by lightly touching shoulders/arms or neck, by vibration and/or pressure to the vertebrae, pelvis and legs. 6. A most effective somatosensory stimulus was sinewave rotation of the body with head stationary. The gain of this directionally selective neck receptor response was in the range of vestibular stimulation. Interaction of vestibular and neck receptor stimulation was either of a cancellation or facilitation type.(ABSTRACT TRUNCATED AT 400 WORDS)

Responses of single neurons in the parietoinsular vestibular cortex of primates.

1. Neurons activated by stimulation of the horizontal and/or vertical vestibular semicircular canals were recorded in the parietoinsular vestibular cortex in four awake Java monkeys (Macaca fascicularis) and three squirrel monkeys (Saimiri sciureus). Steady tilt in darkness or during illumination of a vertically striped cylinder or of the normal laboratory surroundings did not lead to a significant change in PIVC neuron activity. Thus vestibular input to this cortical region seems to be restricted to signals originating in the semicircular canal receptors. 2. Vestibular stimulation in the three main experimental planes (roll, yaw, and pitch) and in planes in between provided clear evidence that optimum activation can be found in planes that do not coincide with the planes of the semicircular canals but are distributed over all possible spatial planes through the head. 3. Definite evidence of clustering in subdivisions of PIVC of neurons responding to the same optimum rotation plane was obtained in squirrel monkeys and is also suggested to exist in PIVC of Java monkeys. 4. Nearly all neurons responding to vestibular stimulation were also activated by visual large-field movement (optokinetic stimulation). Responses to optokinetic stimuli were always at optimum when the direction of the movement pattern corresponded to the optimum vestibular plane. Two classes of visual-vestibular interaction were found: Synergistic neurons were those PIVC cells with the strongest response to visual movement stimulation in the opposite direction to that leading to a maximum response to vestibular stimulation. Antagonistic neurons had a response maximum when the visual stimulus was moved in the direction of optimum vestibular stimulation. 5. Most PIVC neurons responded to stimulation of the deep mechanoreceptors in the neck region. This input from the neck receptors was tested quantitatively only in the horizontal plane (trunk rotation with the head fixed in space or head rotation with the trunk fixed in space). It interacted with vestibular signals at the PIVC neurons either in an antagonistic or a synergistic manner, the latter meaning activation during rotation of the head in the same direction as that leading to activation induced by semicircular canal stimulation. 6. In addition to the direction-specific vestibular, visual, and neck receptor inputs, a rather complex somatosensory input to PIVC neurons exists, including responses to stimulation of mechanoreceptors of the skin, the muscles, and the joint receptors of legs and arms. Total body vibration also led to activation of some of the neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

[Treatable dementia syndromes]. / Behandelbare dementielle Syndrome.

Dementia--a syndrome of acquired intellectual deterioration--is an etiologically non-specific condition which is permanent, progressive, or reversible. In the evaluation of demented patients, a careful exposure history will determine the possible role of drugs, metals, or toxins. The physical examination may reveal focal deficits in cases of intracranial mass lesions and spasticity or ataxia of the lower limbs if hydrocephalus is present. Coexistance of dementia and peripheral neuropathy usually indicates a toxic or metabolic disorder. Asterixis, myoclonus, and postural tremor are common in toxic-metabolic dementias, while resting tremor, choreoathetosis, and rigidity occur in progressive extrapyramidal disorders. EEG is focally abnormal in cases of cerebral mass lesions and exhibits generalized slowing in toxic-metabolic encephalopathies. CT will aid in the identification of hydrocephalus, subdural hematomas, and intracranial mass lesions. A thorough laboratory evaluation including complete blood count, erythrocyte sedimentation rate, electrolytes, blood urea nitrogen and blood sugar, liver and thyroid tests, calcium and phosphorus levels, B12 and folate levels, serum copper and ceruloplasmin, VDRL, chest X-ray, electrocardiogram, and lumbar puncture may demonstrate treatable disorders that are adversely affecting intellectual function. Elderly individuals are particularly susceptible to the effects of toxic or metabolic disorders, and a mild dementia might be exaggerated by relatively minor fluctuations in metabolic status. Treatable causes of dementia should be considered in all demented patients.

Three methods to elicit sigma-optokinetic nystagmus in Java monkeys.

Sigma-optokinetic nystagmus (sigma-OKN) can be elicited in awake Java monkeys (Macaca fascicularis) when stationary periodic visual patterns (grid of black white stripes, row of equally spaced dots) are illuminated stroboscopically. Three methods were found to be useful in inducing the sigma-OKN: postrotatory nystagmus, optokinetic afternystagmus (OKAN) following normal OKN and a gradual transition from phi-movement (phi-OKN) to sigma-OKN. The properties found for sigma-OKN in man are also present in monkeys with the one exception that monkeys have a long-lasting sigma-OKAN in darkness which is not present in man. The average angular speed Ve of sigma-OKN slow phases was related to the flash frequency fs and the spatial period Ps of the stripe pattern according to the following equation: Ve = k.Ps . fs [degrees . s-1] The constant k was 1 or close to 1.