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Biomedical subjects

B E Stein

Publications and source records attributed to B E Stein.

At least 37 records · Page 2Linked to original sources
PubMed1997

Response properties of corticotectal and corticostriatal neurons in the posterior lateral suprasylvian cortex of the cat.

Lateral suprasylvian cortex (LS) is an important source of visual projections to both the striatum and superior colliculus. Although these two LS efferent systems are likely to be involved in different aspects of visual processing, little is known about their functional properties. In the present experiments, 86 neurons in halothane-anesthetized, paralyzed cats were recorded along the posterior aspects of the medial and lateral banks of LS (PMLS and PLLS). Neurons were selected for analysis on the basis of antidromic activation from electrodes chronically implanted in the superior colliculus and caudate nucleus. The segregated nature of corticostriatal and corticotectal neurons was apparent; in no instance could a neuron be antidromically activated from both the superior colliculus and the caudate nucleus. Many common features were revealed between corticotectal and corticostriatal neurons; the majority of neurons in both populations were binocular and contralaterally dominant, showed similar responses to stationary flashed light, and expressed within-field spatial summation and surround inhibition. However, a number of information-processing features distinguished between corticotectal and corticostriatal neurons; the former were generally tuned to lower velocities than were the latter, and, for a given eccentricity in visual space, corticotectal neurons had smaller receptive fields than did corticostriatal neurons. Moreover, most corticotectal neurons displayed a marked preference for movements toward temporal visual space, whereas corticostriatal neurons revealed no specialization for a particular direction of movement. In addition, whereas corticotectal neurons were selective for receding stimuli, corticostriatal neurons were selective for approaching stimuli. The presence of these two corticofugal pathways is discussed in relation to their presumptive functional roles in the facilitation of attentive and orientation behaviors.

Action Potentials↗
PubMed1997

Development of multisensory neurons and multisensory integration in cat superior colliculus.

The development of multisensory neurons and multisensory integration was examined in the deep layers of the superior colliculus of kittens ranging in age from 3 to 135 d postnatal (dpn). Despite the high proportion of multisensory neurons in adult animals, no such neurons were found during the first 10 d of postnatal life. Rather, all sensory-responsive neurons were unimodal. The first multisensory neurons (somatosensory-auditory) were found at 12 dpn, and visually responsive multisensory neurons were not found until 20 dpn. Early multisensory neurons responded weakly to sensory stimuli, had long latencies, large receptive fields, and poorly developed response selectivities. Most surprising, however, was their inability to integrate combinations of sensory cues to produce significant response enhancement (or depression), a characteristic feature of the adult. Responses to combinations of sensory cues differed little from responses to their modality-specific components. At 28 dpn an abrupt physiological change was noted. Some multisensory neurons now integrated combinations of cross-modality cues and exhibited significant response enhancements when these cues were spatially coincident and response depressions when the cues were spatially disparate. During the next 2 months the incidence of multisensory neurons, and the proportion of these neurons capable of adult-like multisensory integration, gradually increased. Once multisensory integration appeared in a given neuron, its properties changed little with development. Even the youngest integrating neurons showed superadditive enhancements and spatial characteristics of multisensory integration that were indistinguishable from the adult. Nevertheless, neonatal and adult multisensory neurons differed in the manner in which they integrated temporally asynchronous stimuli, a distribution that may reflect the very different behavioral requirements at different ages. The possible maturational role of corticotectal projections in the abrupt gating of multisensory integration is discussed.

Acoustic Stimulation↗
PubMed1997

Visual response properties and visuotopic representation in the newborn monkey superior colliculus.

Visual response properties and visuotopic representation in the newborn monkey superior colliculus. J. Neurophysiol. 78: 2732-2741, 1997. Visually responsive neurons were recorded in the superior colliculus (SC) of the newborn rhesus monkey. The receptive fields of these neurons were larger than those in the adult, but already were organized into a well-ordered map of visual space that was very much like that seen in mature animals. This included a marked expansion of the representation of the central 10 degrees of the visual field and a systematic foveal to peripheral increase in receptive field size. Although newborn SC neurons had longer response latencies than did their adult counterparts, they responded vigorously to visual stimuli and exhibited many visual response properties that are characteristic of the adult. These included surround inhibition, within-field spatial summation, within-field spatial inhibition, binocularity, and an adult-like ocular dominance distribution. As in the adult, SC neurons in the newborn preferred a moving visual stimulus and had adult-like selectivities for stimulus speed. The developmentally advanced state of the functional circuitry of the newborn monkey SC contrasts with the comparative immaturity of neurons in its visual cortex. It also contrasts with observations on the state of maturation of the newborn SC in other developmental models (e.g., cat). The observation that extensive visual experience is not necessary for the development of many adult-like SC response properties in the monkey SC may help explain the substantial visual capabilities shown by primates soon after birth.

Aging↗
PubMed1997

Mechanisms of within- and cross-modality suppression in the superior colliculus.

The present studies were initiated to explore the basis for the response suppression that occurs in cat superior colliculus (SC) neurons when two spatially disparate stimuli are presented simultaneously or in close temporal proximity to one another. Of specific interest was examining the possibility that suppressive regions border the receptive fields (RFs) of unimodal and multisensory SC neurons and, when activated, degrade the neuron's responses to excitatory stimuli. Both within- and cross-modality effects were examined. An example of the former is when a response to a visual stimulus within its RF is suppressed by a second visual stimulus outside the RF. An example of the latter is when the response to a visual stimulus within the visual RF is suppressed when a stimulus from a different modality (e. g., auditory) is presented outside its (i.e., auditory) RF. Suppressive regions were found bordering visual, auditory, and somatosensory RFs. Despite significant modality-specific differences in the incidence and effectiveness of these regions, they were generally quite potent regardless of the modality. In the vast majority (85%) of cases, responses to the excitatory stimulus were degraded by >/=50% by simultaneously stimulating the suppressive region. Contrary to expectations and previous speculations, the effects of activating these suppressive regions often were quite specific. Thus powerful within-modality suppression could be demonstrated in many multisensory neurons in which cross-modality suppression could not be generated. However, the converse was not true. If an extra-RF stimulus inhibited center responses to stimuli of a different modality, it also would suppress center responses to stimuli of its own modality. Thus when cross-modality suppression was demonstrated, it was always accompanied by within-modality suppression. These observations suggest that separate mechanisms underlie within- and cross-modality suppression in the SC. Because some modality-specific tectopetal structures contain neurons with suppressive regions bordering their RFs, the within-modality suppression observed in the SC simply may reflect interactions taking place at the level of one input channel. However, the presence of modality-specific suppression at the level of one input channel would have no effect on the excitation initiated via another input channel. Given the modality-specificity of tectopetal inputs, it appears that cross-modality interactions require the convergence of two or more modality-specific inputs onto the same SC neuron and that the expression of these interactions depends on the internal circuitry of the SC. This allows a cross-modality suppressive signal to be nonspecific and to degrade any and all of the neuron's excitatory inputs.

Acoustic Stimulation↗
PubMed1997

A simple enzyme histochemical method for the simultaneous demonstration of acetylcholinesterase and monoamine oxidase in fixed-frozen sections.

We describe an enzyme histochemical technique for the simultaneous demonstration of acetylcholinesterase (AChE) and monoamine oxidase (MAO) (Types A, B, or A+B) in fixed-frozen sections. Several regions in the mesencephalon and brainstem were examined for both somatic and neuropil labeling. The results obtained are equivalent or superior to those obtained using previous methods for the individual localization of these enzymes. The simultaneous visualization of AChE and MAO in the same section allows the relationship of the two enzymes to be easily assessed with brightfield microscopy.

Acetylcholinesterase↗
PubMed1996

The role of anterior ectosylvian cortex in cross-modality orientation and approach behavior.

Physiological and behavioral studies in cat have shown that corticotectal influences play important roles in the information-processing capabilities of superior colliculus (SC) neurons. While corticotectal inputs from the anterior ectosylvian sulcus (AES) play a comparatively small role in the unimodal responses of SC neurons, they are particularly important in rendering these neurons capable of integrating information from different sensory modalities (e.g., visual and auditory). The present experiments examined the behavioral consequences of depriving SC neurons of AES inputs, and thereby compromising their ability to integrate visual and auditory information. Selective deactivation of a variety of other cortical areas (posterolateral lateral suprasylvian cortex, PLLS; primary auditory cortex, AI; or primary visual cortex, 17/18) served as controls. Cats were trained in a perimetry device to ignore a brief, low-intensity auditory stimulus but to orient toward and approach a nearthreshold visual stimulus (a light-emitting diode, LED) to obtain food. The LED was presented at different eccentricities either alone (unimodal) or combined with the auditory stimulus (multisensory). Subsequent deactivation of the AES, with focal injections of a local anesthetic, had no effect on responses to unimodal cues regardless of their location. However, it profoundly, though reversibly, altered orientation and approach to multisensory stimuli in contralateral space. The characteristic enhancement of these responses observed when an auditory cue was presented in spatial correspondence with the visual stimulus was significantly degraded. Similarly, the inhibitory effect of a spatially disparate auditory cue was significantly ameliorated. The observed effects were specific to AES deactivation, as similar effects were not obtained with deactivation of PLLS, AI or 17/18, or saline injections into the AES. These observations are consistent with postulates that specific cortical-midbrain interactions are essential for the synthesis of multisensory information in the SC, and for the orientation and localization behaviors that depend on this synthesis.

Anesthetics, Local↗
PubMed1996

Nociceptive neurones in rat superior colliculus. I. Antidromic activation from the contralateral predorsal bundle.

Accumulating evidence suggests that the rodent superior colliculus (SC) plays as important a role in avoidance and defensive behaviours as it does in orientation and approach. These two complementary behaviours are associated with two anatomically segregated tectofugal output pathways, such that orientation and approach are mediated by the crossed descending projection, whereas avoidance and defence are subserved via the uncrossed projection. Because nociceptive neurones in the SC have been presumed to participate in withdrawal or defensive behaviours, it has been proposed that they have direct access only to the uncrossed efferent pathway. However, in certain behavioural situations, the most adaptive response to injury, or to a painful object in prolonged contact with the skin, is to orient towards the source of discomfort so that the skin can be licked and/or the offending object removed. Presumably then, nociceptive as well as low-threshold neurones would have access to the crossed descending pathway in order to initiate such behaviours. Determining whether or not this is the case was the objective of the present study. Both nociceptive-specific (82%) and wide-dynamic-range (18%) SC neurones were identified using long-duration (up to 6 s), frankly noxious mechanical and thermal stimuli in urethane-anaesthetised Long-Evans hooded rats. The majority (85.7%) of the nociceptive neurones encountered were located within the intermediate layers, which corresponds with the location of the cells-of-origin of the crossed descending projection. Nearly half (44.9%) were activated antidromically from electrical stimulation of the crossed descending pathway at a site in the brainstem below its decussation. The mean conduction velocity of these nociceptive output neurones was 9.02 m/s, which corresponds well to previous estimates of conduction velocity in the crossed tecto-reticulo-spinal tract. These data demonstrate that a significant proportion of nociceptive neurones in the rat SC have axons that project to the contralateral brainstem via the crossed descending projection. Nociceptive neurones could, therefore, effect orientation responses to noxious stimuli via similar output pathways that low-threshold neurones utilize to initiate orientation to innocuous stimuli.

Animals↗
PubMed1996

Nociceptive neurones in rat superior colliculus. II. Effects of lesions to the contralateral descending output pathway on nocifensive behaviours.

A wealth of evidence implicates the crossed descending projection from the superior colliculus (SC) in orientation and approach behaviours directed towards novel, non-noxious stimuli. In our preceding paper, we identified a population of nociceptive neurones in the rat SC that have axons that project to the contralateral brainstem via this output pathway. The purpose of the present study was, therefore, to evaluate the prediction that the crossed descending projection of the SC is also involved in the control of orientation and approach movements of the head and mouth made during the localisation of persistent noxious stimuli. An independent-groups design was used to test the effects of interrupting the contralateral descending projection from the SC on the behavioural reactions elicited by noxious mechanical stimuli presented to the tail and hindpaws. In different groups of animals, a microwire knife was used to cut the contralateral descending fibres at two different locations: (1) a sagittal cut at the level of the dorsal tegmental decussation; (2) a bilateral coronal cut of the predorsal bundle at the level of the medial pontine reticular formation. Retrograde anatomical tracing techniques were then used to evaluate the effectiveness of the cuts and to assess possible involvement of non-collicular fibre systems in both lesioned and control animals. Additional behavioural procedures were performed to test for general neurological status and responsiveness of animals to non-noxious stimuli. Anatomical tracing data indicated that the largest population of neurones with fibres severed by both cuts were the cells-of-origin of the contralateral descending projection in the intermediate white layer of the SC. Behavioural results showed that significantly more animals in both lesion groups failed to locate and bite a mechanical clip placed on the tail. Instead of switching to motor behaviours to localise and remove noxious stimuli, they persisted with defensive reactions, which included freezing, vocalisation or forward and backward escape. In contrast, when the clip was placed on the hindpaws, it was successfully localised by most lesioned and control animals; however, lesioned animals had reliably longer latencies and spent less time in close contact with the clip. Consistent with the established role of the contralateral descending projection in non-noxious orientation, lesioned animals also showed orienting deficits to a range of non-noxious sensory stimuli. These data suggest that, under certain behavioural circumstances, nociceptive information from the SC is integral to the elaboration of orienting and approach movements of the head and mouth elicited by persistent noxious stimuli.

Animals↗
PubMed1996

Comparisons of cross-modality integration in midbrain and cortex.

Multisensory neurons are abundant in the superior colliculus and anterior ectosylvian cortex of the cat. Despite the fact that these areas receive inputs from different regions, and are likely to be involved in different functional roles, there multisensory neurons have many fundamental similarities. They all have multiple receptive fields, one for each sensory input, and these receptive fields overlap one another. It is this spatial correspondence among receptive fields that determines the manner in which both populations of neurons integrate the inputs they receive from different sensory channels. Several principles of integration characterize both cortical and midbrain multisensory neurons, and these constancies in the fundamentals of cross-modality integration are likely to provide a basis for coherence at different levels of the neuraxis. Yet there are also obvious differences in these populations of multisensory neurons. Cortical receptive fields are significantly larger than those in the midbrain, have a lower incidence of suppressive surrounds, and exhibit less cross-modality inhibitory interactions than in the midbrain. Presumably, these differences reflect a greater emphasis on non-spatial aspects of cross-modality integration in cortex than is required by the orientation and localization functions mediated by the superior colliculus.

Animals↗
PubMed1996

Sensory organization of the superior colliculus in cat and monkey.

The sensory representations and response properties of neurons in the multisensory layers of the superior colliculus (SC) of the cat and monkey are strikingly similar. In both species, significant numbers of unimodal visual, auditory, and somatosensory neurons are intermixed, and share modality-specific stimulus selectivities. In addition, these neurons have receptive fields that are organized in similar map-like representations, with the different maps sharing the same axes and, thus, exhibiting a characteristic cross-modality correspondence. Both species also have a large contingent of multisensory neurons that synthesize information from different sensory modalities using a common set of spatial, temporal, and physical principles. These findings suggest that, despite differences in the ontogeny and behavioral repertoires of cat and monkey, there is a substantial conservation in the organization and functional properties of SC neurons. Apparently, these functional features of the SC are adaptive in a wide variety of ecological situations.

Animals↗
PubMed1996

Spatial determinants of multisensory integration in cat superior colliculus neurons.

1. Although a representation of multisensory space is contained in the superior colliculus, little is known about the spatial requirements of multisensory stimuli that influence the activity of neurons here. Critical to this problem is an assessment of the registry of the different receptive fields within individual multisensory neurons. The present study was initiated to determine how closely the receptive fields of individual multisensory neurons are aligned, the physiological role of that alignment, and the possible functional consequences of inducing receptive-field misalignment. 2. Individual multisensory neurons in the superior colliculus of anesthetized, paralyzed cats were studied with the use of standard extracellular recording techniques. The receptive fields of multisensory neurons were large, as reported previously, but exhibited a surprisingly high degree of spatial coincidence. The average proportion of receptive-field overlap was 86% for the population of visual-auditory neurons sampled. 3. Because of this high degree of intersensory receptive-field correspondence, combined-modality stimuli that were coincident in space tended to fall within the excitatory regions of the receptive fields involved. The result was a significantly enhanced neuronal response in 88% of the multisensory neurons studied. If stimuli were spatially disparate, so that one fell outside its receptive field, either a decreased response occurred (56%), or no intersensory effect was apparent (44%). 4. The normal alignment of the different receptive fields of a multisensory neuron could be disrupted by passively displacing the eyes, pinnae, or limbs/body. In no case was a shift in location or size observed in a neuron's other receptive field(s) to compensate for this displacement. The physiological result of receptive-field misalignment was predictable and based on the location of the stimuli relative to the new positions of their respective receptive fields. Now, for example, one component of a spatially coincident pair of stimuli might fall outside its receptive field and inhibit the other's effects. 5. These data underscore the dependence of multisensory integrative responses on the relationship of the different stimuli to their corresponding receptive fields rather than to the spatial relationship of the stimuli to one another. Apparently, the alignment of different receptive fields for individual multisensory neurons ensures that responses to combinations of stimuli derived from the same event are integrated to increase the salience of that event. Therefore the maintenance of receptive-field alignment is critical for the appropriate integration of converging sensory signals and, ultimately, elicitation of adaptive behaviors.

Acoustic Stimulation↗
PubMed1996

Representation and integration of multiple sensory inputs in primate superior colliculus.

1. The properties of visual-, auditory-, and somatosensory-responsive neurons, as well as of neurons responsive to multiple sensory cues (i.e., multisensory), were examined in the superior colliculus of the rhesus monkey. Although superficial layer neurons responded exclusively to visual stimuli and visual inputs predominated in deeper layers, there was also a rich nonvisual and multisensory representation in the superior colliculus. More than a quarter (27.8%) of the deep layer population responded to stimuli from more than a single sensory modality. In contrast, 37% responded only to visual cues, 17.6% to auditory cues, and 17.6% to somatosensory cues. Unimodal- and multisensory-responsive neurons were clustered by modality. Each of these modalities was represented in map-like fashion, and the different representations were in alignment with one another. 2. Most deep layer visually responsive neurons were binocular and exhibited poor selectivity for such stimulus characteristics as orientation, velocity, and direction of movement. Similarly, most auditory-responsive neurons had contralateral receptive fields and were binaural, but had little frequency selectivity and preferred complex, broad-band sounds. Somatosensory-responsive neurons were overwhelmingly contralateral, high velocity, and rapidly adapting. Only rarely did somatosensory-responsive neurons require distortion of subcutaneous tissue for activation. 3. The spatial congruence among the different receptive fields of multisensory neurons was a critical feature underlying their ability to synthesize cross-modal information. 4. Combinations of stimuli could have very different consequences in the same neuron, depending on their temporal and spatial relationships. Generally, multisensory interactions were evident when pairs of stimuli were separated from one another by < 500 ms, and the products of these interactions far exceeded the sum of their unimodal components. Whether the combination of stimuli produced response enhancement, response depression, or no interaction depended on the location of the stimuli relative to one another and to their respective receptive fields. Maximal response enhancements were observed when stimuli originated from similar locations in space (as when derived from the same event) because they fell within the excitatory receptive fields of the same multisensory neurons. If, however, the stimuli were spatially disparate such that one fell beyond the excitatory borders of its receptive field, either no interaction was produced or this stimulus depressed the effectiveness of the other. Furthermore, maximal response interactions were seen with the pairing of weakly effective unimodal stimuli. As the individual unimodal stimuli became increasingly effective, the levels of response enhancement to stimulus combinations declined, a principle referred to as inverse effectiveness. Many of the integrative principles seen here in the primate superior colliculus are strikingly similar to those observed in the cat. These observations indicate that a set of common principles of multisensory integration is adaptable in widely divergent species living in very different ecological situations. 5. Surprisingly, a few multisensory neurons had individual receptive fields that were not in register with one another. This has not been noted in multisensory neurons of other species, and these "anomalous" receptive fields could present a daunting problem: stimuli originating from the same general location in space cannot simultaneously fall within their respective receptive fields, a stimulus pairing that may result in response depression. Conversely, stimuli that originate from separate events and disparate locations (and fall within their receptive fields) may result in response enhancement. However, the spatial principle of multisensory integration did not apply in these cases. (ABSTRACT TRUNCATED)

Animals↗
PubMed1994

Response properties of nociceptive and low-threshold neurons in rat trigeminal pars caudalis.

There is little doubt that trigeminal nociceptive neurons play a critical role in signaling the presence of harmful, or potentially harmful, orofacial stimuli. Unfortunately, there is only a limited understanding of how these neurons code such stimuli and whether this code is maintained in those structures responsible for generating overt reactions. The present series of experiments were designed to quantitatively document the response properties of nociceptive neurons in the rat trigeminal pars caudalis using the same electrical and innocuous and/or noxious mechanical and thermal stimuli employed in the characterization of nociceptive neurons with orofacial receptive fields in the rat superior colliculus. Neurons were classified as either low-threshold mechanoreceptive, wide-dynamic-range, or nociceptive-specific (type I, II) depending on their responsiveness to these stimuli. Nociceptive pars caudalis neurons (92/135, 68%) had receptive field organizations and input fibers (as indicated by latencies to electrical stimuli) quite different from those of low-threshold neurons (43/135, 32%). Nociceptive stimulus-response relationships for the population of wide-dynamic-range and nociceptive-specific type I neurons to contact heat stimuli were positively accelerating power functions with exponents of 3.9 and 4.4, respectively. This contrasted sharply with the low-threshold component of wide-dynamic-range neurons which was a negatively accelerating power function with an exponent of 0.7. All categories of nociceptive neurons also responded vigorously to cold stimuli. The thresholds of both hot and cold stimuli were often below psychophysical estimates of thermal pain, suggesting that "nociceptive" neurons process far more information than that required to signal potentially harmful stimuli. The fundamental similarities in nociceptive properties in pars caudalis and other structures of the central nervous system suggest that there is little transformation of the information encoded at successive levels of the neuraxis. This is consistent with the idea that the functional role of nociceptive neurons is reflected more in which circuits they are integrated and less in differences in their physiological properties.

Animals↗
PubMed1994

Cross-modal synthesis in the midbrain depends on input from cortex.

1. The synthesis of information from different sensory modalities in the superior colliculus is an important precursor of attentive and orientation behavior. 2. This integration of multisensory information is critically dependent on inputs from a small area of association cortex, the anterior ectosylvian sulcus. Removal of these corticotectal influences can have a remarkably specific effect: it can eliminate multisensory integration in superior colliculus neurons while leaving their responses to unimodal cues intact. 3. Apparently, some of the associative functions of cortex are accomplished via its target neurons in the midbrain.

Animals↗
PubMed1994

Functional development of a central visual map in cat.

1. The onset of visual activity in the superficial layers of the cat superior colliculus begins abruptly at about 6 days postnatal (DPN), just before natural eye opening. Despite the presence of many inactive sites at this time, the systematic nature of the superior colliculus visuotopy is already evident. The number of inactive sites across the horizontal dimension of the superficial layers decreases rapidly so that by 9-10 DPN most sites are visually responsive. 2. Initially, visual activity is restricted to the topmost portion of the superficial gray layer, where W-cell terminals predominate, but rapidly extends down to include Y-cell territory at 10 DPN. 3. In contrast to what might have been expected based on earlier behavioral observations, there was no physiological evidence for a central-to-peripheral gradient in the development of the superior colliculus visuotopy. Rather, the entire visual field is well represented long before the expression of any visually initiated behaviors. 4. In contrast to the rapidity of the appearance and organization of the visual representation in superficial layers, deep layers remain refractory to visual stimuli for weeks.

Aging↗
PubMed1994

Vaccinating elderly people. Protecting from avoidable disease.

A large portion of our older adult patients remain unimmunised or inadequately immunised against tetanus. The US is unique in that clinical tetanus occurs mostly in persons aged over 60 years. Worldwide, it is a disease of neonates. Both pneumococcal diseases and influenza cause markedly greater morbidity and mortality among elderly people compared with younger people. The prevalence of these chronic diseases can be decreased by immunising susceptible persons against the relevant infections. Hepatitis B is also a worldwide problem, causing a large number of acute infections and costly sequelae, 95% of which is preventable by hepatitis B vaccine. Rabies is a very lethal disease preventable by use of rabies vaccine. The decreased function of the aging immune system results in far fewer older persons developing antibodies following immunisation than their younger counterparts.

Adult↗
PubMed1994

Avoiding drug reactions: seven steps to writing safe prescriptions.

Two-thirds of patients age 65 and older use one or more drugs daily. The number of drugs taken by older patients greatly influences their chances of experiencing a drug reaction. Many patients take their medications incorrectly, and a large number receive prescriptions from more than one physician. The physiologic changes that occur with aging also affect drug absorption, distribution, protein binding, biotransformation, and excretion (pharmacokinetics). Drugs may react with other drugs, with chronic disease, with alcohol, and with nutrients in the patient's diet. By careful prescribing, however, the physician can minimize the potential for ill effects of multiple drug therapies for older patients. Seven prescribing steps are outlined.

Aftercare↗